ionex IonPac I -AS1 Analytical olumn...The Dionex IonPac ICE-AS1 is composed of a 7.5 µm...
Transcript of ionex IonPac I -AS1 Analytical olumn...The Dionex IonPac ICE-AS1 is composed of a 7.5 µm...
For Research Use Only. Not for use in diagnostic procedures.
Dionex IonPac ICE-AS1 Analytical Column
031181 Revision 07 • March 2017
User M
anu
al
Thermo Scientific Product Manual for Dionex IonPac ICE-AS1 Column Page 2 of 52 031181-07 For Research Use Only. Not for use in diagnostic procedures.
Product Manual
for
Dionex IonPac ICE-AS1 Analytical Column (9 x 150 mm, P/N 302622)
(9 x 250 mm, P/N 043197)
(4 x 250 mm, P/N 064198)
Thermo Scientific Product Manual for Dionex IonPac ICE-AS1 Column Page 3 of 52 031181-07 For Research Use Only. Not for use in diagnostic procedures.
© 2017 Thermo Fisher Scientific Inc. All rights reserved.
All trademarks are the property of Thermo Fisher Scientific Inc. and its subsidiaries.
Thermo Fisher Scientific Inc. provides this document to its customers with a product purchase to use in the product
operation. This document is copyright protected and any reproduction of the whole or any part of this document is
strictly prohibited, except with the written authorization of Thermo Fisher Scientific Inc.
The contents of this document are subject to change without notice. All technical information in this document is
for reference purposes only. System configurations and specifications in this document supersede all previous
information received by the purchaser.
Thermo Fisher Scientific Inc. makes no representations that this document is complete, accurate or error free and
assumes no responsibility and will not be liable for any errors, omissions, damage or loss that might result from
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For Research Use Only. Not for Use in Diagnostic Procedures.
Revision History:
Revision 04, March, 2017, Reformatted for Thermo Fisher Scientific Inc. Added information for 9 x 150 mm, P/N 302622.
Thermo Scientific Product Manual for Dionex IonPac ICE-AS1 Column Page 4 of 52 031181-07 For Research Use Only. Not for use in diagnostic procedures.
Safety and Special Notices
Make sure you follow the precautionary statements presented in this guide. The safety and other
special notices appear in boxes.
Safety and special notices include the following:
Indicates a potentially hazardous situation which, if not avoided, could result in death or
serious injury.
Indicates a potentially hazardous situation which, if not avoided, could result in damage
to equipment.
Indicates a potentially hazardous situation which, if not avoided, may result in minor or
moderate injury. Also used to identify a situation or practice that may seriously damage
the instrument, but will not cause injury.
Indicates information of general interest.
IMPORTANT
Highlights information necessary to prevent damage to software, loss of data, or invalid
test results; or might contain information that is critical for optimal performance of the
system.
Tip Highlights helpful information that can make a task easier.
SAFETY
!
WARNING
!
CAUTION
!
NOTE
!
Contents
Thermo Scientific Product Manual for Dionex IonPac ICE-AS1 Column Page 5 of 52 031181-07 For Research Use Only. Not for use in diagnostic procedures.
Contents
Contents................................................................................................................................................................... 5
1. Introduction ..................................................................................................................................................... 7
2. Exclusion Chromatography System .................................................................................................................. 9
3. Installation ..................................................................................................................................................... 11
3.1 System Requirements ............................................................................................................................ 11
3.2 System Void Volume............................................................................................................................. 11
3.3 The Injection Loop ................................................................................................................................ 11
3.4 Eluent Storage ....................................................................................................................................... 11
3.5 Dionex ACRS-ICE 500 Suppressor Requirements .................................................................................. 11
4. Operation ...................................................................................................................................................... 12
4.1 General Operating Conditions ................................................................................................................ 12
4.2 Dionex IonPac ICE-AS1 Operation Precautions ..................................................................................... 12
4.3 Chemical Purity Requirements ............................................................................................................... 12
4.3.1 Inorganic Chemicals...................................................................................................................... 12
4.3.2 Deionized Water ........................................................................................................................... 12
4.3.3 Solvents ........................................................................................................................................ 13
4.4 Eluent Preparation ................................................................................................................................. 14
4.4.1 Acid Eluent Preparation ................................................................................................................ 14
4.4.2 Eluents Containing Solvents .......................................................................................................... 14
4.5 Anion Suppression Regenerant Preparation ............................................................................................ 14
5. Example Applications ..................................................................................................................................... 15
5.1 Preparation of Eluents ........................................................................................................................... 15
5.2 pKa Values of Selected Organic Acids ................................................................................................... 15
5.3 Dionex IonPac ICE-AS1 Elution Plots and Tables .................................................................................. 18
5.3.1 Dionex IonPac ICE-AS1 Run Time vs. Eluent Strength ................................................................. 18
5.3.2 Dionex IonPac ICE-AS1 Run Time vs. Eluent Strength (Expanded Scale)...................................... 19
5.3.3 Dionex IonPac ICE-AS1 Run Time vs. Temperature...................................................................... 21
5.4 Production Test Chromatogram ............................................................................................................. 22
5.4.1 Dionex IonPac ICE-AS1 9 x 250 mm ............................................................................................ 22
5.4.2 Dionex IonPac ICE-AS1 4 x 250 mm ............................................................................................ 24
5.5 Comparison of Dionex IonPac ICE-AS1 and Dionex IonPac ICE-AS6 for C1 - C6 Retention (9 x 250 mm)
25
5.6 Temperature Effects .............................................................................................................................. 26
5.7 UV Detection with Dionex IonPac ICE-AS1 .......................................................................................... 27
5.8 The Addition of Solvent to the Eluent to Reduce Run Time .................................................................... 28
5.9 Analysis of Aliphatic and Hydroxy Acids .............................................................................................. 29
Contents
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5.10 Analysis of Various Organic Acids ........................................................................................................ 30
5.11 Use of Solvent to Optimize Selectivity ................................................................................................... 31
5.12 Tracking Degradation of Acrylic Acid in an Organic Acid Mix .............................................................. 32
5.13 Analysis of Silicate in a Plating Bath Matrix .......................................................................................... 33
5.14 Analysis of Organic Acids in a 52% Nitric Acid Matrix ......................................................................... 34
5.15 Analysis of Cyanide Using the Dionex IonPac ICE-AS1 Column ........................................................... 35
5.16 Pulsed Amperometric Detection of Sulfite ............................................................................................. 36
5.17 Analysis of Carbonate and Tetraborate Using the Dionex IonPac ICE-AS1 Column ............................... 37
5.18 Analysis of Aliphatic Alcohols Using Pulsed Amperometric Detection ................................................... 38
5.19 Glycols Separation ................................................................................................................................ 39
5.20 Nitriles: Acetronitrile and Propionitrile .................................................................................................. 40
5.21 Ketones: Acetone and 2-Butatone .......................................................................................................... 41
5.22 Alkene (I): Acrylic Acid and Propionic Acid .......................................................................................... 42
5.23 Alkyne: 3-Butyn-2-one and 2-Butatone .................................................................................................. 43
6. Troubleshooting ............................................................................................................................................. 44
6.1 High Back Pressure ............................................................................................................................... 45
6.1.1 Finding the Source of High System Pressure .................................................................................. 45
6.1.2 Replacing Column Bed Support Assemblies .................................................................................. 46
6.2 High Background or Noise .................................................................................................................... 47
6.2.1 Preparation of Eluents ................................................................................................................... 47
6.2.2 A Contaminated Guard or Analytical Column ................................................................................ 47
6.2.3 Contaminated Hardware ................................................................................................................ 47
6.2.4 A Contaminated Anion Chemically Regenerated Suppressor for ICE, Dionex ACRS-ICE 500 ....... 47
6.3 Poor Peak Resolution............................................................................................................................. 48
6.3.1 Loss of Column Efficiency ............................................................................................................ 48
6.3.2 Poor Resolution Due to Shortened Retention Times ....................................................................... 48
6.3.3 Loss of Front End Resolution ........................................................................................................ 49
6.4 Spurious Peaks ...................................................................................................................................... 49
6.5 Split Peaks ............................................................................................................................................ 50
Appendix A – Column Care ................................................................................................................................... 51
A.1 Recommended Operation Pressures ....................................................................................................... 51
A.2 Column Start-Up ................................................................................................................................... 51
A.3 Column Storage ..................................................................................................................................... 51
A.4 Column Cleanup.................................................................................................................................... 51
A.5 Choosing the Appropriate Cleanup Solution ........................................................................................... 52
A.6 Column Cleanup Procedure ................................................................................................................... 52
1 – Introduction
Thermo Scientific Product Manual for Dionex IonPac ICE-AS1 Column Page 7 of 52 031181-07 For Research Use Only. Not for use in diagnostic procedures.
1. Introduction
Ion exclusion uses a fully sulfonated resin with a dilute solution of strong acid as eluent for the separation of weak acid anions. The retention mechanisms are Donnan exclusion, steric exclusion,
and adsorption partition. A strong acid eluent facilitates protonation of weak organic acids. In the
neutral form, these acids are not subject to Donnan exclusion and penetrate into the pores of
negatively charged sulfonated polystyrene/divinylbenzene resin. Separation is accomplished by
differences in pKa's, size, and hydrophobicity of the acid anions. The Donnan exclusion
mechanism causes stronger acid anions to elute before weaker acid anions according to increasing
pKa. For example, acetate (pK=4.56) elutes before propionate (pK=4.67). The adsorption
mechanism causes hydrophilic acid anions to elute before hydrophobic acid anions. For example,
tartrate elutes before succinate due to its two hydroxyls. Strong organic acid anions, such as
oxalate (pK=1.04) and pyruvate (pK=2.26, which remain totally or partially ionized) are subjected
to Donnan exclusion and elute early. Strong mineral acid anions are totally excluded and elute in
the void.
Dionex IonPac ICE-AS1 columns are stable between pH 0 - 7 and they are compatible with
eluents containing 0 ‑ 50% HPLC solvents such as methanol or acetonitrile. (Do not run eluents
with cations other than hydronium ion through the Dionex IonPac ICE-AS1.)
Figure 1 The Ion Exclusion Separation
1 – Introduction
Thermo Scientific Product Manual for Dionex IonPac ICE-AS1 Column Page 8 of 52 031181-07 For Research Use Only. Not for use in diagnostic procedures.
The Dionex IonPac ICE-AS1 is composed of a 7.5 µm cross-linked styrene/divinylbenzene resin
that is functionalized with sulfonate groups. The ion exchange capacity of the 9 x 250 mm
analytical column is 27 meq/column. The ion exchange capacity of the 9 x 150 mm analytical
column is 16.2 meq/column. The ion exchange capacity of the 4 x 250 mm analytical column is
5.3 meq/column. The Dionex IonPac ICE-AS1 has low hydrophobicity when compared to the
ICE-AS6. The Dionex IonPac ICE-AS1 also has high solvent compatibility (50%) when
compared to the ICE-AS6 (15%).
When setting up the analytical system, observe the special precautions listed in Section 4,
“Operation.” PEEK (polyetheretherketone) is used to make column hardware. PEEK has excellent
chemical resistance to most organic solvents and inorganic solutions. However, concentrated
sulfuric acid and concentrated nitric acid will attack PEEK. Tetrahydrofuran at concentrations of
greater than 20% is not compatible with PEEK systems. The Dionex IonPac ICE-AS1 Analytical
Column has a minimum efficiency of 9,000 plates/column for acetic acid under standard operating
conditions, and it operates at a back pressure between 600-900 psi (4.14 - 6.20 MPa) at 0.8
mL/min with the test eluent(0.16 mL/min for the 4 x 250 mm). However, both Dionex IonPac
ICE-AS1 columns are capable of operating at back pressures up to 1,000 psi (6.90 MPa). Dionex
IonPac ICE-AS1 Analytical Columns have 10‑32 threaded PEEK end fittings for use with
ferrule/bolt liquid line fittings.
Assistance is available for Dionex Products. In the U.S., call 1-800-346-6390. Outside the U.S.,
contact the nearest Thermo Fisher Scientific office.
2 – Exclusion Chromatography System
Thermo Scientific Product Manual for Dionex IonPac ICE-AS1 Column Page 9 of 52 031181-07 For Research Use Only. Not for use in diagnostic procedures.
2. Exclusion Chromatography System
Table 1 Configuration
Configuration 4-mm 9-mm
Eluent Flow Rate 0.16 mL/min 0.8 mL/min
Dionex Anion Chemically
Regenerated Suppressor for ICE
4mm Dionex ACRS-ICE 500 (P/N
084714)
9mm Dionex ACRS-ICE 500 (P/N
084715)
Injection Loop 2 - 15 μL 10 - 50 μL
System Void Volume Eliminate switching valves,
couplers and the GM-3 Gradient
Mixer. Use only the 2-mm GM-4
Mixer
(P/N 049135).
Minimize dead volume. Switching
valves, couplers can be used. Use
the GM-2, GM-3 or recommended
gradient mixers.
Pumps Use a Thermo Scientific Dionex IC
system in microbore configuration.
Use a Thermo Scientific Dionex IC
system in standard bore configuration.
Detectors Dionex ICS-Series Variable
Wavelength Detector with PEEK
Flow Cell (7 mm, 2.5 µL) (P/N
6074.0300)
Dionex ICS-5000+ CD
Conductivity Detector (analytical)
and Integrated Cell (P/N 079829).
Dionex Integrion CD Conductivity
Detector (P/N 22153-60036).
Dionex ICS-5000+ ED
Electrochemical Detector (P/N
072042) and Cell (P/N 072044).
Recommended back pressure: 30–
40 psi
Dionex ICS-Series Variable
Wavelength Detector with PEEK
Flow Cell (10 mm, 11 µL) (P/N
066346)
Dionex ICS-5000+ CD
Conductivity Detector (analytical)
and Integrated Cell (P/N 079829).
Dionex Integrion CD Conductivity
Detector (P/N 22153-60036).
Dionex ICS-5000+ ED
Electrochemical Detector (P/N
072042) and Cell (P/N 072044).
Recommended back pressure: 30–
40 psi
2 – Exclusion Chromatography System
Thermo Scientific Product Manual for Dionex IonPac ICE-AS1 Column Page 10 of 52 031181-07 For Research Use Only. Not for use in diagnostic procedures.
Table 2 Tubing Back Pressures
Color Item # ID Inches ID cm Volume
mL/cm
Back
Pressure psi/ft at 1
mL/min
Back
Pressure psi/ft at
0.25
mL/min
Back
Pressure psi/cm at 1
mL/min
Green 044777 0.030 0.076 4.560 0.086 0.021 0.003
Orange 042855 0.020 0.051 2.027 0.435 0.109 0.015
Blue 049714 0.013 0.033 0.856 2.437 0.609 0.081
Black 042690 0.010 0.025 0.507 6.960 1.740 0.232
Red 044221 0.005 0.013 0.127 111.360 27.840 3.712
Yellow 049715 0.003 0.008 0.046 859.259 214.815 28.642
3 – Installation
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3. Installation
3.1 System Requirements
The Dionex IonPac ICE-AS1 Analytical Column is designed to be run on any Thermo Scientific Dionex Ion Chromatograph equipped with suppressed conductivity detection.
3.2 System Void Volume
For best performance, all of the tubing installed between the injection valve and detector should
be 0.005" (P/N 044221) ID PEEK tubing. Note that 0.010" ID PEEK tubing (P/N 042690) may
be used but peak efficiency will be compromised which may also result in decreased peak
resolution. Minimize the lengths of all connecting tubing and remove all unnecessary switching
valves and couplers. If you need assistance in properly configuring your system contact technical
support for Dionex Products. In the U.S., call 1-800-346-6390. Outside the U.S., contact the
nearest Thermo Fisher Scientific office.
3.3 The Injection Loop
For most applications on a 4-mm analytical system, a 2-15 µL injection loop will be sufficient.
For the 9-mm column, a 10-50 µL injection loop can be used.
3.4 Eluent Storage
The Dionex IonPac ICE-AS1 column is designed to be used with acid eluent systems and isocratic
analysis. Storage under a helium atmosphere ensures contamination free operation and proper
pump performance. (Nitrogen can be used if eluents do not contain solvents). Acidic eluents that
contain acetonitrile should be made fresh daily. Acetonitrile slowly hydrolyzes in acidic solutions.
3.5 Dionex ACRS-ICE 500 Suppressor Requirements
The Dionex ACRS-ICE 500 Anion Chemically Regenerated Suppressor for ICE (4mm ACRS-ICE 500, P/N 084714 or 2 mm ACRS-ICE 500, P/N 084715) should be used. The Dionex AERS
500 or Dionex ACRS 500 cannot be used for ion exclusion applications that require suppressed
conductivity detection. The Dionex ACRS-ICE 500 is compatible with all solvents and
concentrations as the systems and columns. Use Dionex Cation Regenerant Solution,
Tetrabutylammonium hydroxide (TBAOH, P/N 039602). Dilute as required for the example
applications. For detailed information on the operation of the Dionex ACRS-ICE 500
suppressors, see the "Product Manual for Dionex ACRS-ICE 500 suppressors" (Document No.
032661).
4 – Operation
Thermo Scientific Product Manual for Dionex IonPac ICE-AS1 Column Page 12 of 52 031181-07 For Research Use Only. Not for use in diagnostic procedures.
4. Operation
4.1 General Operating Conditions
The selectivity of the Dionex IonPac ICE-AS1 Analytical Column is designed to separate an extensive group of low molecular weight organics acids in less than 20 minutes. The Dionex
IonPac ICE-AS1 column consists of a cross-linked (8%), microporous, hydrophilic resin that has
been sulfonated. The nature of the cross-linked polymeric structure of the packing material makes
the Dionex IonPac ICE-AS1 columns compatible with pH 0 - 7 eluents (see Section 4.2, “Dionex
IonPac ICE-AS1 Operation Precautions”) and 0 - 50% organic solvent eluents. The Dionex
IonPac ICE-AS1 can be used with any suppressible ionic eluent that does not exceed the capacity
of the Dionex Chemically Regenerated Suppressor for ICE, ACRS-ICE 500.
4.2 Dionex IonPac ICE-AS1 Operation Precautions
Maximum solvent concentration is 50%.
DO NOT use hydroxide eluents.
Filter and degas eluents.
Filter samples.
Maximum recommended operating pressure is 1,000 psi (6.90 MPa).
Always run the column with fresh eluent, with suppressor disconnected,
for about 20 minutes if the column has not been used for a week or longer.
4.3 Chemical Purity Requirements
Obtaining reliable, consistent, and accurate results requires eluents that are free of ionic and
spectrophotometric impurities. Chemicals, solvents, and deionized water used to prepare eluents
must be of the highest purity available. Maintaining low trace impurities and low particle levels
in eluents also help to protect your ion exchange columns and system components. Thermo Fisher
Scientific cannot guarantee proper column performance when the quality of the chemicals, solvents and water used to prepare eluents has been compromised.
4.3.1 Inorganic Chemicals
Reagent Grade inorganic chemicals should always be used to prepare ionic eluents. Whenever
possible, inorganic chemicals that meet or surpass the latest American Chemical Society standard for purity should be used. These inorganic chemicals will show a lot analysis on each label. The
analyses performed in Section 5, “Example Applications,” use heptafluorobutyric acid obtained
from Fluka Chemie AG.
4.3.2 Deionized Water
The deionized water used to prepare eluents should be Type I Reagent Grade Water with a specific
resistance of 18.2 megohm-cm. The deionized water should be free of ionized impurities,
organics, microorganisms, and particulate matter larger than 0.2 µm. Bottled HPLC-Grade Water
(with the exception of Burdick & Jackson) should not be used since most bottled water contains
an unacceptable level of ionic impurities.
CAUTION
!
4 – Operation
Thermo Scientific Product Manual for Dionex IonPac ICE-AS1 Column Page 13 of 52 031181-07 For Research Use Only. Not for use in diagnostic procedures.
4.3.3 Solvents
Solvents can be added to the ionic eluents used with Dionex IonPac ICE-AS1 columns to modify
the ion exchange process or improve sample solubility. The solvents used must be free of ionic
impurities. However, since most manufacturers of solvents do not test for ionic impurities, it is
important that the highest grade of solvents available be used. Currently, several manufacturers
are making ultrahigh purity solvents that are compatible for HPLC and spectrophotometric
applications. These ultrahigh purity solvents will usually ensure that your chromatography is not
affected by ionic impurities in the solvent. Currently at Thermo Fisher Scientific, we have
obtained consistent results using High Purity Solvents manufactured by Burdick and Jackson and
Optima® Solvents by Fisher Scientific.
When using a solvent in an ionic eluent, column generated back pressures will depend on the solvent used, concentration of the solvent, the ionic strength of the eluent and the flow rate used.
The column back pressure will vary as the composition of water-methanol and water-acetonitrile
mixture varies. The practical back pressure limit for the Dionex IonPac ICE-AS1 columns is 2,000
psi.
Table 4 HPLC Solvents for Use with Dionex IonPac ICE-AS1 Columns
Solvent Maximum Operating
Concentration*
Acetonitrile 50%
Methanol 50%
2-Propanol 50%
Tetrahydrofuran 50% * See Section 4.2, “Dionex IonPac ICE-AS1 Operation Precautions”
4 – Operation
Thermo Scientific Product Manual for Dionex IonPac ICE-AS1 Column Page 14 of 52 031181-07 For Research Use Only. Not for use in diagnostic procedures.
4.4 Eluent Preparation
4.4.1 Acid Eluent Preparation
The acidic eluents used with the Dionex IonPac ICE-AS1 columns are stable and require no
special storage. Always prepare eluents with Type I Reagent Grade Water (see Section 4.3.2,
“Deionized Water”) which has been properly degassed.
Eluents that contain solvents should be stored in glass eluent bottles pressurized with helium
(nitrogen is soluble in solvents).
4.4.2 Eluents Containing Solvents
When mixing solvents with water, remember to mix solvent with water on a volume to volume
basis. If a procedure requires an eluent of 10% acetonitrile, prepare the eluent by adding 100 mL
of acetonitrile to an eluent reservoir. Then add 900 mL of deionized water to the acetonitrile in
the reservoir. Using this procedure to mix solvents with water will ensure that a consistent true
volume/volume eluent is obtained. Premixing water with solvent will minimize the possibility of
outgassing.
Degas the aqueous component of the eluent and then add the solvent component. Avoid
excessive purging or degassing of eluents containing solvents if possible, since a volatile
solvent can be “boiled” off from the solution.
4.5 Anion Suppression Regenerant Preparation
The regenerant used with the Dionex ACRS-ICE 500 Suppressor when used with the Dionex
IonPac ICE-AS1 to perform the analyses in Section 5, “Example Applications,” is 5 mM
tetrabutylammonium hydroxide (TBAOH). Use Dionex Cation Regenerant Solution (P/N
039602). Dilute 50 mL of the 0.1 M Cation Regenerant Solution to 1 L with degassed Type I
Reagent Grade Water. Usually 4 liters at a time is prepared. For a guide to properly adjusting the regenerant flow rate, see Document No. 032661, the Product Manual for the Dionex ACRS-ICE
500.
NOTE
!
5 – Example Applications
Thermo Scientific Product Manual for Dionex IonPac ICE-AS1 Column Page 15 of 52 031181-07 For Research Use Only. Not for use in diagnostic procedures.
5. Example Applications
The chromatograms in this section were obtained using columns that reproduced the Production Test Chromatogram (see Section 5.3, “Production Test Chromatogram”) on optimized Ion Chromatographs (see Section 3, “Installation”).
Systems will vary slightly in performance due to slight differences in column sets, system void volumes, liquid sweep-
out times of components, and laboratory temperatures.
The Dionex IonPac ICE-AS1 may be used isocratically for chromatographing a large number of carboxylic acids.
If your sample or standard contains organic acids, adding chromate (about 10 mg/L) will help stabilize them from
bacterial degradation at room temperature.
Before attempting any of the following example applications, ensure your system is properly configured.
Ensure all of the eluents have been made from high purity reagents and deionized water. All water used in the preparation of eluents should be degassed, deionized water. For chemical purity requirements see Section 4.2,
“Chemical Purity Requirements.”
Run synthetic standards to calibrate and confirm the operation of your system. This column has a very high loading
capacity and can handle a large number of dirty samples. If the Dionex IonPac ICE-AS1 shows signs of fouling after
running complex samples, refer to the column cleanup protocols in Appendix A, “Column Care.”
5.1 Preparation of Eluents
The standard eluent for the example applications presented in this section is 1.0 mM heptafluorobutyric acid. It was
prepared from heptafluorobutyric acid (same as perfluorobutyric acid) obtained from FLUKA Chemie AG (P/N 77249).
It is > 99% (GC) purity with a molecular weight of 214.04 and a density of 1.652. It is supplied in 10.0 mL bottles (16.52 g).
Heptafluorobutyric Acid Stock Solution (0.0772 M):
Dilute the entire contents of one 10.0 mL bottle to 1 L.
Heptafluorobutyric Acid Eluent (1.0 mM):
Dilute 13.5 g of the stock solution (0.0772 M) to 1 L.
If you prefer to work from a 0.100 M stock solution, dilute 21.40 g of the > 99% purity heptafluorobutyric acid to 1 L.
The eluent can then be made by diluting 10.0 g of the 0.100 M stock solution to 1 L to obtain the 1.0 mM
heptafluorobutyric acid eluent. Heptafluorobutyric acid was chosen for minimum background conductivity. However,
other mineral acids such as sulfuric and hydrochloric can be used.
5.2 pKa Values of Selected Organic Acids
The following tables list the pKs of selected organic acids in alphabetical order and in ascending order of pK. Organic
acids elute in approximately the order of ascending pK, but additional hydrogen bonding and adsorption variables
modify the elution order slightly so that the elution order of the acids is not strictly in order of ascending pK. The tables
plus the example applications are designed to give the chromatographer a simple method for estimating the ability of
the Dionex IonPac ICE-AS1 to separate various combinations of organic acids.
5 – Example Applications
Thermo Scientific Product Manual for Dionex IonPac ICE-AS1 Column Page 16 of 52 031181-07 For Research Use Only. Not for use in diagnostic procedures.
Table 5 Organic Acids with pK's in Alphabetic order Compound pK1 pK2 pK3
Acetic (ethanoic) 4.56
Aconitic (cis-propene-1,2,3-tricarboxylic) N/A
Acrylic (propenoic) 4.26
Adipic (hexanedioic) 4.26 5.03
Anisic (4-methoxybenzoic) 4.48
Ascorbic 4.03 11.34
Azelaic (nonanedioic) 4.39 5.12
Benzoic 4.00
Bromoacetic 2.72
Butanoic 4.63
Caproic (hexanoic) 4.85
Chloroacetic 2.68
Citraconic (cis-methylbutenedioic) 2.20 5.60
Citric (2-hydroxypropane-1,2,3-tricarboxylic) 2.87 4.35 5.69
Crotonic (trans-but-2-enoic) 4.69
Cyanoacetic 2.63
Dichloroacetic 0.87
Diglycolic (oxydiacetic) 2.79 3.93
Dithiotartaric (2,3-dimercaptobutanedioic) 2.71 3.48 8.89
Fluoroacetic 2.59
Formic (methanoic) 3.55
Fumaric (trans-butenedioic) 2.85 4.10
Galacturonic 3.23 11.42
Gentistic (5-hydroxysalicylic) 2.70
Glutaric (pentanedioic) 4.13 5.03
Glyceric (dl-2,3-dihydroxypropanoic) 3.52
Glycolic (hydroxyacetic) 3.63
Guanidine 13.54
2-Hydroxyisobutyric 3.72
4-Hydroxybenzoic 4.10 9.96
Hippuric (n-benzoylglycine) 3.50
Iodoacetic 2.98
Isobutyric (2-methylpropionic) 4.63
Isocitrate (dl-1-hydroxypropane-1,2,3-tricarboxylic) 3.02 4.28 5.75
Isovaleric (3-methylbutanoic) 4.58
Itaconic (methylenebutanedioic) 3.68 5.14
Ketoglutaric (2-oxopentanedioic) 1.85 4.44
Lactic (d-2-hydroxypropanoic) 3.66
Maleic (cis-butenedioic) 1.75 5.83
Malic (l-hydroxybutanedioic) 3.24 4.71
Malonic (propanedioic) 2.65 5.28
Mandelic (l-phenylhydroxyacetic) 3.19
Mellitic (benzenehexacarboxylic) 0.70 2.21 3.52
3-Mercaptopropanoic 4.34 10.84
Mesaconic (trans-methylbutene) 2.61
Mucic 3.08 3.63
Nitroacetic 1.46
Octanoic 4.89
Orotic (uracil-6-carboxylic) 1.96 9.34
Oxalic (ethanedioic) 1.04 3.82
Phthalic (benzene-1,2-dicarboxylic) 2.75 4.93
Pimelic (heptanedioic) 4.31 5.08
Pivalic (2,2-dimethylpropanoic) 4.83
Propanoic 4.67
Pyruvic (2-oxopropanoic) 2.26
Quinic (1,3,4,5-tetrahydroxycyclohexanecarboxylic) 3.36
Salicylic (2-hydroxybenzoic) 2.81 13.40
Squaric (3,4-dihydroxy-3-cyclobutene-1,2-dione 0.40 3.10
Succinic (butanedioic) 4.00 5.24
Tartaric (d-2,3-dihydroxybutanedioic) 2.82 3.95
Terephthalic
Thioglycolic (mercaptoacetic) 3.42 10.11
Thiolactic (dl-2-mercaptopropanoic) 3.48 10.08
Thiomalic (dl-mercaptobutanedioic) 3.30 4.60 10.38
Trichloroacetic 0.66
Trimellitic (benzene-1,2,4-tricarboxylic) 2.40 3.71 5.01
Uric (2,6,8-trihydroxypurine) 5.61
Valeric (pentanoic) 4.64
Vinylacetic (but-3-enoic) 4.12
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Table 6 Organic Acids with pK's in Order of Increasing pK1 Compound pK1 pK2 pK3
Aconitic (cis-propene-1,2,3-tricarboxylic) N/A
Terephthalic
Squaric (3,4-dihydroxy-3-cyclobutene-1,2-dione 0.40 3.10
Trichloroacetic 0.66
Mellitic (benzenehexacarboxylic) 0.70 2.21 3.52
Dichloroacetic 0.87
Oxalic (ethanedioic) 1.04 3.82
Nitroacetic 1.46
Maleic (cis-butenedioic) 1.75 5.83
Ketoglutaric (2-oxopentanedioic) 1.85 4.44
Orotic (uracil-6-carboxylic) 1.96 9.34
Citraconic (cis-methylbutenedioic) 2.20 5.60
Pyruvic (2-oxopropanoic) 2.26
Trimellitic (benzene-1,2,4-tricarboxylic) 2.40 3.71 5.01
Fluoroacetic 2.59
Mesaconic (trans-methylbutene) 2.61
Cyanoacetic 2.63
Malonic (propanedioic) 2.65 5.28
Chloroacetic 2.68
Gentistic (5-hydroxysalicylic) 2.70
Dithiotartaric (2,3-dimercaptobutanedioic) 2.71 3.48 8.89
Bromoacetic 2.72
Phthalic (benzene-1,2-dicarboxylic) 2.75 4.93
Diglycolic (oxydiacetic) 2.79 3.93
Salicylic (2-hydroxybenzoic) 2.81 13.40
Tartaric (d-2,3-dihydroxybutanedioic) 2.82 3.95
Fumaric (trans-butenedioic) 2.85 4.10
Citric (2-hydroxypropane-1,2,3-tricarboxylic) 2.87 4.35 5.69
Iodoacetic 2.98
Isocitrate (dl-1-hydroxypropane-1,2,3-tricarboxylic) 3.02 4.28 5.75
Mucic 3.08 3.63
Mandelic (l-phenylhydroxyacetic) 3.19
Galacturonic 3.23 11.42
Malic (l-hydroxybutanedioic) 3.24 4.71
Thiomalic (dl-mercaptobutanedioic) 3.30 4.60 10.38
Quinic (1,3,4,5-tetrahydroxycyclohexanecarboxylic) 3.36
Thioglycolic (mercaptoacetic) 3.42 10.11
Thiolactic (dl-2-mercaptopropanoic) 3.48 10.08
Hippuric (n-benzoylglycine) 3.50
Glyceric (dl-2,3-dihydroxypropanoic) 3.52
Formic (methanoic) 3.55
Glycolic (hydroxyacetic) 3.63
Lactic (d-2-hydroxypropanoic) 3.66
Itaconic (methylenebutanedioic) 3.68 5.14
2-Hydroxyisobutyric 3.72
Benzoic 4.00
Succinic (butanedioic) 4.00 5.24
Ascorbic 4.03 11.34
4-Hydroxybenzoic 4.10 9.96
Vinylacetic (but-3-enoic) 4.12
Glutaric (pentanedioic) 4.13 5.03
Acrylic (propenoic) 4.26
Adipic (hexanedioic) 4.26 5.03
Pimelic (heptanedioic) 4.31 5.08
3-Mercaptopropanoic 4.34 10.84
Azelaic (nonanedioic) 4.39 5.12
Anisic (4-methoxybenzoic) 4.48
Acetic (ethanoic) 4.56
Isovaleric (3-methylbutanoic) 4.58
Butanoic 4.63
Isobutyric (2-methylpropionic) 4.63
Valeric (pentanoic) 4.64
Propanoic 4.67
Crotonic (trans-but-2-enoic) 4.69
Pivalic (2,2-dimethylpropanoic) 4.83
Caproic (hexanoic) 4.85
Octanoic 4.89
Uric (2,6,8-trihydroxypurine) 5.61
Guanidine 13.54
5 – Example Applications
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5.3 Dionex IonPac ICE-AS1 Elution Plots and Tables
The following tables show the effect of eluent strength on retention time for a large group of low molecular weight
organic acids. Table 4 is an expanded scale of Table 3. These tables are useful for determining the optimum eluent
strength to minimize co-elution. Table 5 lists, in ascending order, the retention times of common organic acids using
0.4 mM, 1.0 mM, 2.0 mM, and 5.0 mM HCl as eluent.
5.3.1 Dionex IonPac ICE-AS1 Run Time vs. Eluent Strength
Figure 1 Run Time vs. Eluent Strength
BO3
HIBA
Shikimic
Lactic
Glycolic
Fumaric
Br-Acetic
Cl-Acetic
Tricarballyic
Threonic
Quinic
Malic
Malonic
Citriconic
Citric
Tartaric
Caproic
Veleric
Butyric
CO3
Acrylic
Propionic
Adipic
Acetic
Glutaric
B-OH-Butyric
Formic
Itaconic
Succinic
0.2 1.2 2.2 3.2 4.2 5.2
5
15
25
35
45
Eluent Strength: mM HCl
Rete
nti
on
Tim
e(m
inu
tes)
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5.3.2 Dionex IonPac ICE-AS1 Run Time vs. Eluent Strength (Expanded Scale)
Figure 2 RunTime vs. Eluent Strength (Expanded Scale)
BO3
HIBA
Shikimic
Lactic
Glycolic
Fumaric
Br-Acetic
Cl-Acetic
Tricarballyic
Threonic
Quinic
Malic
Malonic
Citriconic
Citric
Tartaric
Butyric
CO3
Acrylic
Propionic
Adipic
Acetic
Glutaric
B-OH-Butyric
Formic
ItaconicSuccinic
0 1 2 3 4 5
18
17
16
15
14
13
12
11
10
9
8
7
6
Eluent Strength: mM HCl
Rete
nti
on
Tim
e(m
inu
tes)
5 – Example Applications
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Table 7 Dionex IonPac ICE-AS1 Run Times vs. Eluent Strength, Ambient
Solute 0.4 mM HCl 1.0 mM HCl 2.0 mM HCl 5 mM HCl
Tartaric 6.73 7.07 7.37 7.87
Citric 6.73 6.92 7.13 8.45
Citriconic 6.75 7.12 7.62 9.13
Malonic 7.03 7.38 7.87 8.83
Malic 7.57 7.90 8.12 8.53
Quinic 7.63 8.02 8.28 8.60
Threonic 7.70 8.18 8.45
Tricarballyic 7.70 7.97 8.20 8.42
Cl-Acetic 8.05 9.17 10.33 12.87
Br-Acetic 8.65 10.25 11.98 14.65
Fumaric 8.80 10.27 11.35 13.37
Glycolic 9.47 9.88 10.10 10.45
Lactic 9.48 10.05 10.13 10.42
Shikimic 9.48 9.80 9.83 9.98
HIBA 9.58 10.07 10.07 10.27
BO3 9.68 9.55 9.55
Succinic 9.70 10.08 9.95 10.27
Itaconic 9.78 10.22 10.48 10.90
Formic 9.90 10.90 11.32 11.60
B-OH-Butyric 10.77 10.80 11.02 10.98
Glutaric 11.50 12.00 11.77 12.03
Acetic 12.33 12.55 12.58 12.42
Adipic 13.72 13.85 13.78 14.12
Propionic 14.37 14.58 14.62 14.43
Acrylic 14.52 15.17 15.15 15.38
CO3 15.85 15.67 15.73
Butyric 17.50 17.83 17.88 17.62
Valeric 25.53 26.02 26.08 25.52
Caproic 41.02 41.70 41.55 40.32
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5.3.3 Dionex IonPac ICE-AS1 Run Time vs. Temperature
Temperature can effect the retention time and the selectivity of organic acids. Thermo Fisher Scientific tests all ion-
exclusion columns at 19°C to ensure reproducible retention times. As shown in the plot below, retention times decrease
slightly with increasing temperature. Laboratories can have widely varying temperatures throughout the day (some as
high as ± 5°C); it is advisable to use temperature control to maintain reproducible retention times. This can be done
with any of the Thermo Scientific Dionex ion chromatography systems and modules equipped with temperature
control.. If a temperature control device is not available, it is recommended to keep the system away from any
heating/cooling vents located in the laboratory to minimize wide temperature swings.
Figure 3 Run Time vs. Temperature
5 – Example Applications
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5.4 Production Test Chromatogram
5.4.1 Dionex IonPac ICE-AS1 9 x 250 mm
Isocratic elution of organic anions has been optimized on the Dionex IonPac ICE-AS1 Analytical Column. To guarantee
that all Dionex IonPac ICE-AS1 Analytical Columns meet high quality and reproducible performance specification
standards, all columns undergo the following production control test.
The large dip in the baseline which occurs at approximately 5 minutes is the total exclusion volume of the column. This
is the volume of liquid in the column which is external to the resin beads. The total permeation or void volume of the
column, the combined resin bead internal and external liquid volume, creates a baseline disturbance at approximately
13 minutes. This baseline disturbance, however, can only be seen at sensitivities higher than 1 µS full scale.
Sample Loop Volume: 50 μL Analytical Column: IonPac ICE-AS1 9 x 250 mm Analytical Column Eluent: 1.0 mM Heptafluorobutyric acid Eluent Flow Rate: 0.8 mL/min Suppressor: AMMS-ICE II Regenerant: 5 mM Tetrabutylammonium hydroxide Regenerant Flow : 5 mL/min Expected Background Conductivity: 80-90 μS
Expected System Operating Back pressure: < 1000 psi Temperature: 19°C
Figure 4a Dionex IonPac ICE-AS1 9 x 250 mm Test Chromatogram
Peak pK mg/L
(ppm)
1. Nitrate 50
2. Glycolate 3.63 30
3. Formate 3.55 20
4. Acetate 4.56 40
5. Propionate 4.67 60
5 – Example Applications
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Figure 4b Dionex IonPac ICE-AS1 9 x 150 mm Test Chromatogram
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5.4.2 Dionex IonPac ICE-AS1 4 x 250 mm
Isocratic elution of organic anions has been optimized on the Dionex IonPac ICE-AS1 Analytical Column. To guarantee
that all Dionex IonPac ICE-AS1 Analytical Columns meet high quality and reproducible performance specification
standards, all columns undergo the following production control test.
The large dip in the baseline which occurs at approximately 5 minutes is the total exclusion volume of the column. This
is the volume of liquid in the column which is external to the resin beads. The total permeation or void volume of the
column, the combined resin bead internal and external liquid volume, creates a baseline disturbance at approximately
13 minutes. This baseline disturbance, however, can only be seen at sensitivities higher than 1 µS full scale.
Sample Loop Volume: 50 μL Analytical Column: IonPac ICE-AS1 4 x 250 mm Analytical Column Eluent: 1.0 mM Heptafluorobutyric acid Eluent Flow Rate: 0.16 mL/min Suppressor: AMMS-ICE II Regenerant: 5 mM Tetrabutylammonium hydroxide Regenerant Flow : 5 mL/min Expected Background Conductivity: 80-90 μS
Expected System Operating Back pressure: < 1000 psi Temperature: 19°C
Figure 4c Dionex IonPac ICE-AS1 4 x 250 mm Test Chromatogram
Peak pK mg/L
(ppm)
1. Nitrate 50
2. Glycolate 3.63 30
3. Formate 3.55 20
4. Acetate 4.56 40
5. Propionate 4.67 60
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5.5 Comparison of Dionex IonPac ICE-AS1 and Dionex IonPac ICE-AS6 for C1 - C6 Retention (9 x 250 mm)
The Dionex IonPac ICE-AS1 column can easily resolve straight chain organic acids, formic through caproic, by ion
exclusion retention. In comparison, the added adsorption and hydrogen bonding on the ICE-AS6 does not improve the
already excellent resolution, but does increase the run time, requiring the addition of solvent to the eluent to achieve
reasonable run times.
Analytical Column: See Chromatogram
Eluent: See Chromatogram
Eluent Flow Rate: See Chromatogram
Suppressor: AMMS-ICE II
Regenerant: 5 mM Tetrabutylammonium Hydroxide
Temperature: 19°C
Figure 5 Dionex IonPac ICE-AS1 and Dionex IonPac ICE-AS6 Retention Comparison for C1-C6
Analytical Column: Dionex IonPac ICE-AS1 9 x 250 mm
Eluent: 0.4 mM Heptafluorobutyric Acid
Flow Rate: 0.8 mL/min
Analytical Column: Dionex IonPac ICE-AS1 9 x 250 mm
Eluent: 0.4 mM Heptafluorobutyric Acid in 20% Acetonitrile
Flow Rate: 1.0 mL/min
Peaks pK's
1. Formic 3.55
2. Acetic 4.56
3. Propionic 4.67
4. Butyric 4.63
5. Valeric 4.64
6. Caproic 4.85
5 – Example Applications
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5.6 Temperature Effects
The following examples demonstrate the effects of temperature upon the run times and selectivity for Dionex IonPac
ICE-AS1 columns.
Sample Loop Volume: 50µL Analytical Column: Dionex IonPac ICE-AS1 9 x 250 mm Analytical Column Eluent: 1.0 mM Heptafluorobutyric acid Eluent Flow Rate: 0.8 mL/min. Suppressor: AMMS-ICE II Regenerant: 5 mN Tetrabutylammonium hydroxide Regenerant Flow: 5 mL/min.
Background Conductivity: 20 µS System Operating Back Pressure: 600 psi (4.14 MPa)
Acid pKa mg/L 1. Nitrate 50 2. Malate 3.24, 4.71 20 3. Glycolate 3.63 40 4. Formate 3.55 20
5. Acetate 4.56 40 6. Propionate 4.67 60
Figure 6 Temperature Effects for C1-C6 on the Dionex IonPac ICE-AS1
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5.7 UV Detection with Dionex IonPac ICE-AS1
The following example demonstrates the use of UV detection of organic acids using a high acid concentration for
eluent. Acid concentrations above 2 mN exclude the use of suppressed conductivity. Although UV detection can be
used at low acid strengths, the sensitivity and selectivity is not as favorable compared to conductivity detection.
Sample Loop Volume: 50 µL
Analytical Column: Dionex IonPac ICE-AS1 9 x 250 mm Analytical Column
Eluent: 10 mN Sulfuric Acid
Eluent Flow Rate: 0.8 mL/min
Detection: UV, 210 nm
Expected System Operating Back pressure: < 1000 psi
Figure 7 UV Detection Using the Dionex IonPac ICE-AS1
Peak pK's mg/L
(ppm)
1. Tartaric 2.82, 3.95 30
2. Quinic 3.36 30
3. Succinic 4.00, 5.24 30
4. Formic 3.55 30
5. Acetic 4.56 30
6. Adipic 4.26, 5.03 30
7. Acrylic 4.26 1
8. Butyric 4.85 40
9. Valeric 4.64 50
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5.8 The Addition of Solvent to the Eluent to Reduce Run Time
The following example demonstrates the addition of solvent to the eluent to optimize the run time of a C1 to C6 organic
acid run. By adding 10% acetonitrile to the eluent the total run time is reduced from 44 minutes to 24 minutes.
Sample Loop Volume: 50 µL
Analytical Column: Dionex IonPac ICE-AS1 9 x 250 mm Analytical Column
Eluent: 1 mM Heptafluorobutyric acid
Eluent Flow Rate: 0.8 mL/min
Suppressor: AMMS-ICE II
Regenerant; 5 mM TBAOH
Regenerant Flow : 5 mL/min
Expected Background Conductivity: 80-90 µS
Expected System Operating Back pressure: < 1000 psi
Temperature: 19°C
Figure 8 Addition of Solvent to the Eluent to Reduce Retention Time
Peak pK's
1. Formic 3.55
2. Acetic 4.56
3. Propionic 4.83
4. Butyric 4.63
5. Valeric 4.64
6. Caproic 4.85
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5.9 Analysis of Aliphatic and Hydroxy Acids
The Dionex IonPac ICE-AS1 column is capable of separating both aliphatic as well as hydroxy aliphatic acids.
Sample Loop Volume: 50 µL
Analytical Column: Dionex IonPac ICE-AS1 9 x 250 mm Analytical Column
Eluent: 1 mM Heptafluorobutyric acid
Eluent Flow Rate: 0.8 mL/min
Suppressor: AMMS-ICE II
Regenerant; 5 mM TBAOH
Regenerant Flow : 5 mL/min
Expected Background Conductivity: 80-90 µS
Expected System Operating Back pressure: < 1000 psi
Temperature: 19°C
Figure 9 Separation of Aliphatic and Hydroxy Acids
Peak pK's mg/L
(ppm)
1. Tartaric 2.82, 3.95 10
2. Malic 3.24, 4.71 20
3. Glycolic 3.63 30
4. Formic 3.55 30
5. Acetic 4.56 30
6. Propionic 4.67 40
7. Butyric 4.63 50
5 – Example Applications
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5.10 Analysis of Various Organic Acids
Many different types of organic acids can be analyzed with the Dionex IonPac ICE-AS1 column. Here is an example
of a cyclic hydroxy acid (quinic) as well as mono- and dicarboxylic acids which contain double bonds (acrylic and
itaconic).
Sample Loop Volume: 50 µL
Analytical Column: Dionex IonPac ICE-AS1 9 x 250 mm Analytical Column
Eluent: 1 mM Perfluorobutyric Acid
Eluent Flow Rate: 0.8 mL/min
Suppressor: AMMS-ICE II
Regenerant: 5 mM TBAOH
Regenerant Flow : 5 mL/min
Expected Background Conductivity: 80-90 µS
Expected System Operating Back Pressure: <1000 psi
Temperature: 19°C
Figure 10 Analysis of Organic Acids Containing Double Bonds
Peak pK's mg/L
(ppm)
1. Tartaric 2.82, 3.95 30
2. Quinic 3.36 30
3. Succinic 4.00, 5.24 30
4. Itaconic 3.68, 5.14 25
5. Acetic 4.56 30
6. Acrylic 4.26 20
7. Butyric 4.63 50
5 – Example Applications
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5.11 Use of Solvent to Optimize Selectivity
In addition to decreasing run time (see Section 5.7), solvents added to the eluent can also be used to optimize selectivity.
This example shows the reversal of elution order for adipic and acetic acids by increasing acetonitrile from 5% to 10%.
Sample Loop Volume: 50 µL
Analytical Column: Dionex IonPac ICE-AS1 9 x 250 mm Analytical Column
Eluent: 1 mM Heptafluorobutyric acid
Eluent Flow Rate: 0.8 mL/min
Suppressor: AMMS-ICE II
Regenerant: 5 mM TBAOH
Regenerant Flow: 5 mL/min
Expected Background Conductivity: 80-90 µS
Expected System Operating Back pressure: < 1000 psi
Temperature: 19°C
Figure 11 Using Solvent to Optimize Selectivity
Peak pK's
1. Glutaric 4.13, 5.03
2. Acetic 4.56
3. Adipic 4.26, 5.03
Peak pK's
1. Glutaric 4.13, 5.03
2. Acetic 4.56
3. Adipic 4.26, 5.03
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5.12 Tracking Degradation of Acrylic Acid in an Organic Acid Mix
The Dionex IonPac ICE-AS1 column can be used to track the degradation of acrylic acid. The dimer and trimer
oligomer degradation products of acrylic acid are shown.
Sample Loop Volume: 50 µL
Analytical Column: Dionex IonPac ICE-AS1 9 x 250 mm Analytical Column
Eluent: 1 mM Perfluorobutyric Acid
Eluent Flow Rate: 0.8 mL/min
Suppressor: AMMS-ICE II
Regenerant; 5 mM TBAOH
Regenerant Flow : 5 mL/min
Expected Background Conductivity: 80-90 µS
Expected System Operating Back pressure: < 1000 psi
Temperature: 19°C
Figure 12 Tracking Degradation of Acrylic Acid in an Organic Acid Matrix
Peaks: mg/L pK's
(ppm)
1. Malic 50 3.24, 4.71
2. Fumaric 1 2.85, 4.10
3. Acrylic 5 4.26
4. acrylic dimer
5. acrylic trimer
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5.13 Analysis of Silicate in a Plating Bath Matrix
The following example shows the analysis of silicate in a plating bath sample. This application cannot be accomplished
on an anion exchange column due to the high ionic strength of the matrix. The sample contains percent levels of
chromate and sulfate. On the Dionex IonPac ICE-AS1 column, silicate can be separated from these anions which elute
in the void volume.
Sample Loop Volume: 50 µL
Analytical Column: Dionex IonPac ICE-AS1 9 x 250 mm Analytical Column
Eluent: 5 mM Hydrochloric Acid
Eluent Flow Rate: 1.0 mL/min
Detector: VIS, 410 nm
PCR: 20 mM Sodium Molybdate, 0.2 M Nitric Acid
6 mM Sodium Lauryl Sulfate
Flow Rate: 0.5 mL/min
Figure 13 Silicate in a Plating Bath Matrix
Peak mg/L
(ppm)
1. Silicate 78
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5.14 Analysis of Organic Acids in a 52% Nitric Acid Matrix
Ion exclusion using the Dionex IonPac ICE-AS1 allows for the analysis of organic acids in the presence of very large
amounts of ionic species. The nitrate ion is excluded from the sulfonated ion exclusion resin. Eluting in the void, this
allows the analysis of organic acids in the presence of strong acid. In this example a solution diluted to 1% nitric acid
was injected.
Sample Loop Volume: 50 µL
Analytical Column: Dionex IonPac ICE-AS1 9 x 250 mm Analytical Column
Eluent: 1mM Octanesulfonic Acid
Eluent Flow Rate: 0.8 mL/min
Suppressor: AMMS-ICE II
Regenerant; 10 mM TBAOH
Regenerant Flow : 3 mL/min
Expected Background Conductivity: 40 µS
Expected System Operating Back pressure: < 1000 psi
Figure 14 Analysis of Organic Acids in a 52% Nitric Acid Matrix
Peaks: pK's
1. Nitric Acid
2. Succinic 4.00, 5.24
3. Glutaric 4.13, 5.03
4. Adipic 4.26, 5.03
5 – Example Applications
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5.15 Analysis of Cyanide Using the Dionex IonPac ICE-AS1 Column
The following example shows the analysis of cyanide using the Dionex IonPac ICE-AS1 column. The Dionex ACRS-
ICE 500 suppressor is used with 0.5 M NaOH to adjust the post column eluent pH for optimized amperometric detection
of cyanide using an electrode.
Sample Loop Volume: 50 µL
Analytical Column: Dionex IonPac ICE-AS1 9 x 250 mm Analytical Column
Eluent: 0.1M Nitric Acid
Eluent Flow Rate: 0.8 mL/min
Suppressor: AMMS-ICE II
Regenerant; 0.5 M NaOH
Regenerant Flow : 5 mL/min
Detection: Electrochemical, Ag electrode
Expected System Operating Back pressure: <1000 psi
Figure 15 Analysis of Cyanide
Peak mg/L
(ppm)
1. Cyanide 10
5 – Example Applications
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5.16 Pulsed Amperometric Detection of Sulfite
The following example shows the analysis of sulfite in various food matrices using pulsed amperometric detection.
Sample Loop Volume: 50 µL
Analytical Column: Dionex IonPac ICE-AS1 9 x 250 mm Analytical Column
Eluent: 20 mN Sulfuric Acid
Eluent Flow Rate: 1.0 mL/min
Detection: Pulsed Amperometric Detection, Pt electrode
Figure 16 Pulsed Amperometric Detection of Sulfite
5 – Example Applications
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5.17 Analysis of Carbonate and Tetraborate Using the Dionex IonPac ICE-AS1 Column
The following example shows the analysis of carbonate and tetraborate using the Dionex IonPac ICE-AS1 column with
suppressed conductivity detection.
Sample Loop Volume: 50 µL
Analytical Column: Dionex IonPac ICE-AS1 9 x 250 mm Analytical Column
Eluent: 0.1 mM Perchloric Acid, 100 mM Mannitol
Eluent Flow Rate: 1.0 mL/min
Suppressor: AMMS-ICE II
Temperature: 19°C
Figure 17 Analysis of Carbonate and Tetraborate
Peaks mg/L
(ppm) 1. Tetraborate 10
2. Carbonate 80
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5.18 Analysis of Aliphatic Alcohols Using Pulsed Amperometric Detection
The following shows the analysis of aliphatic alcohols using pulsed amperometric detection.
Sample Loop Volume: 25 µL
Analytical Column: Dionex IonPac ICE-AS1 9 x 250 mm Analytical Column
Eluent: 50 mM Perchloric Acid
Eluent Flow Rate: 0.8 mL/min
Detection: ED 40, Pt electrode
Figure 18 Analysis of Aliphatic Alcohols Using Pulsed Amperometric Detection
Time(S) potential (V) integration
0.00 0.40
0.28 0.40 Begin
0.30 0.40 End
0.31 0.40
0.32 1.40
0.44 1.40
0.45 -0.40
0.88 -0.40
Peak mg/L
(ppm)
1. Sorbitol 50
2. Xylitol 50
3. Erythritol 50
4. Glycerol 20
5. Ethylene Glycol 20
6. Methanol 50
7. Ethanol 50
8. 2-Propanol 200
9. 1-Propanol 200
10. 2-Butanol 200
11. 1-Butanol 100
12. 3-Methyl-1-Propanol 300
5 – Example Applications
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5.19 Glycols Separation
The following shows the analysis of glycols using amperometric detection and a disposable platinum electrode.
Figure 19 Analysis of Glycols
5 – Example Applications
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5.20 Nitriles: Acetronitrile and Propionitrile
The following shows the analysis of nitriles using amperometric detection and a disposable platinum electrode.
Figure 20 Analysis of Nitriles: Acetonitrile and Propionitrile
5 – Example Applications
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5.21 Ketones: Acetone and 2-Butatone
The following shows the analysis of ketones using amperometric detection and a disposable platinum electrode.
Figure 21 Analysis of Ketones: Acetone and 2-Butatone
5 – Example Applications
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5.22 Alkene (I): Acrylic Acid and Propionic Acid
The following shows the analysis of alkenes using amperometric detection and a disposable platinum electrode.
Figure 22 Analysis of Alkene (I): Acrylic Acid and Propionic Acid
5 – Example Applications
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5.23 Alkyne: 3-Butyn-2-one and 2-Butatone
The following shows the analysis of alkynes using amperometric detection and a disposable platinum electrode.
Figure 23 Analysis of Alkynes: 3-Butyn-2-one and 2-Butatone
6 – Troubleshooting
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6. Troubleshooting
The purpose of the Troubleshooting Guide is to help you solve operating problems that may arise while using the Dionex IonPac ICE-AS1 column. For more information on problems that originate
with the Ion Chromatograph (IC) or the suppressor, refer to the Troubleshooting Guide in the
appropriate operator’s manual. If you cannot solve the problem on your own, contact the technical
support for Dionex Products. In the U.S., call 1-800-346-6390. Outside the U.S., contact the
nearest Thermo Fisher Scientific office.
Table 8 Dionex IonPac ICE-AS1 Troubleshooting Summary
Observation Cause Action Reference Section
High Back Pressure Unknown Component
Plugged Column Bed Supports
Plugged System Hardware
Isolate Blockage
Replace Bed Supports
Unplug, Replace
6.1.1
6.1.2
Component Manual
High Background
Conductivity
Dionex ACRS-ICE 500
Not Suppressing
Contamination
Bad Eluents
Contaminated Column
Contaminated Dionex ACRS-ICE 500
Hardware Operation
Proportioning Valve
Check Regenerant Flow Rate
Check Eluent Flow Rate
Remake Eluents
Clean Column
Clean Suppressor
Service Valve
6.2.4 A, Component Manual
6.2.4 B, Component Manual
6.2, 6.3.2 B, 6.3.3 A
6.2.2, 6.3.2 C, 6.3.2 D, 6.4 A, 6.4 B
6.2.4 C, Component Manual
Component Manual
Poor Peak Resolution
Poor Efficiency Large System Void Volume
Sluggish Injection Valve
Column Headspace
Column Overloading
Replumb System
Service Valve
Replace Column
Reduce Sample Size
6.3.1 B, Component Manual
6.3.3 C, 6.4 C, Component Manual
6.3.1 A
6.3.3 B
Fronting Peaks Column Overloading Reduce Sample Size 6.3.3 B
Tailing Peaks Contaminated Dionex ACRS-ICE 500 Clean Suppressor 6.2.4 C, Component Manual
Short Retention Times Flow Rate Too Fast
Bad Eluents
Column Contamination
Recalibrate Pump
Remake Eluents
Clean Column
6.3.2 A
6.3.2 B
6.2.2, 6.3.2 C, 6.3.2 D, 6.4 A, 6.4 B
Spurious Peaks
or
Negative Peaks
Column Contamination
Sluggish Injection Valve
Excessive Carbonate
Standard Too Old
Pretreat Samples
Service Valve
Degass Eluent
Make New Standard
Keep Refrigerated
6.3.2 C, 6.4 A
6.3.3 C, 6.4 C, Component Manual
6.3.2 C, 6.4 A
6.3.3 C, 6.4 C, Component Manual
6 – Troubleshooting
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6.1 High Back Pressure
6.1.1 Finding the Source of High System Pressure
Total system pressure, when using the Dionex IonPac ICE-AS1 9 x 250 mm Analytical Column
at 0.8 mL/min, should be less than 1000 psi (6.9 MPa) when using the test chromatogram
conditions. When using the Dionex IonPac ICE-AS1 4 x 250 mm Analytical Column at 0.16
mL/min, total system pressure should be less than 1000 psi (6.9 MPa). Refer to Section 4.3.3,
“Solvents,” to see how solvent concentration can affect the column operating pressure. If the
system pressure is higher than 1000 psi (6.9 MPa), it is advisable to determine the cause of the
high system pressure.
The system should be used with a High-Pressure In-Line Filter (P/N 074505) for eluents. The
filter should be positioned between the gradient pump outlet and the injection valve. Ensure a High-Pressure In-Line Filter is in place and that it is not contaminated.
A. Set the pump to the correct eluent flow rate. Higher than recommended eluent flow rates
will cause higher pressure. Measure the pump flow rate if necessary with a stop watch
and graduated cylinder.
B. Find out what part of the system is causing the high pressure. It could be a piece of tubing that has plugged, collapsed tubing walls from over tightening, an injection valve
with a plugged port, a column with particulates plugging the bed support, a plugged
High-Pressure In-Line Filter, the suppressor, or the detector cell.
To find out which part of the chromatographic system is causing the problem,
disconnect the pump eluent line from the injection valve and turn the pump on. Watch
the pressure; it should not exceed 50 psi (0.34 MPa). Continue adding the system
components (injection valve, column(s), suppressor and the detector) one by one, while
watching the system pressure. The pressure should increase up to a maximum of 1000
psi (6.9 MPa) at a flow rate of 0.8 mL/min when the 9 x 250 mm column is connected.
The suppressor may add up to 130 psi (0.90 MPa). No other components should add
more than 100 psi (0.69 MPa) of pressure. Refer to the appropriate manual for cleanup or replacement of the problem component.
6 – Troubleshooting
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6.1.2 Replacing Column Bed Support Assemblies
If the column inlet bed support is determined to be the cause of the high back pressure, it should
be replaced. To change the inlet bed support assembly, refer to the following instructions, using
one of the two spare inlet bed support assemblies included in the ship kit.
A. Disconnect the column from the system.
B. Carefully unscrew the inlet (top) column fitting. Use two open end wrenches.
C. Remove the bed support assembly. Turn the end fitting over and tap it against a benchtop
or other hard, flat surface to remove the bed support and seal assembly. If the bed support
must be pried out of the end fitting, use a sharp pointed object such as a pair of tweezers,
but be careful that you DO NOT SCRATCH THE WALLS OF THE END FITTING.
Discard the old bed support assembly.
D. Place a new bed support into the end fitting. Make sure that the end of the column tube
is clean and free of any particulate matter so that it will properly seal against the bed
support assembly. Use the end of the column to carefully start the bed support assembly
into the end fitting.
Dionex IonPac ICE-AS1 9 x 250 mm Column
/ Dionex IonPac ICE-AS1 9 x 150 mm Column
(P/N 043197 or 302622)
Dionex IonPac ICE-AS1 4 x 250
mm Column (P/N 064198)
Support Assembly P/N 048238 P/N 042955
Zitex® Bed Support P/N 048297 P/N 060528
End Fitting P/N 048298 P/N 052809
If the column tube end is not clean when inserted into the end fitting, particulate matter
may obstruct a proper seal between the end of the column tube and the bed support
assembly. If this is the case, additional tightening may not seal the column but instead
damage the column tube or the end fitting. Carefully wipe the sealing surfaces clean before
assembling
E. Screw the end fitting back onto the column. Tighten it fingertight, then an additional 1/4
turn (25 in x lb). Tighten further only if leaks are observed.
F. Reconnect the column to the system and resume operation.
DO NOT attempt to remove the outlet column fitting as the resin will extrude out of the
column and ruin it.
CAUTION
!
NOTE
!
6 – Troubleshooting
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6.2 High Background or Noise
In a properly working system, the background conductivity levels expected for several eluent
systems are shown below:
ELUENT EXPECTED BACKGROUND CONDUCTIVITY
0.2 mM heptafluorobutyric acid 13 - 15 µS
0.4 mM heptafluorobutyric acid 23 - 25 µS
1.6 mM heptafluorobutyric acid 78 - 82 µS
6.2.1 Preparation of Eluents
A. Ensure the eluents and the regenerant are made correctly.
B. Ensure the eluents are made from chemicals with the recommended purity.
C. Ensure the deionized water used to prepare the reagents has a specific resistance of 18.2
megohm-cm.
6.2.2 A Contaminated Guard or Analytical Column
Remove the Dionex IonPac ICE-AS1 Analytical Column from the system. Connect the fluid lines
to a piece of back pressure tubing. If the background conductivity decreases, then the column is
the cause of the high background conductivity; clean the column as instructed in, “Column
Cleanup” (see Column Care in Appendix A).
6.2.3 Contaminated Hardware
To eliminate the hardware as the source of the high background conductivity, bypass the
suppressor and pump deionized water with a specific resistance of 18.2 megohm-cm through the
system. The background conductivity should be less than 2 µS. If it is not, check the
detector/conductivity cell calibration by injecting deionized water directly into it. See the
appropriate manual for details.
6.2.4 A Contaminated Anion Chemically Regenerated Suppressor for ICE, Dionex ACRS-ICE 500
If the above items have been checked and the problem persists, the suppressor is probably causing
the problem.
A. Check the regenerant flow rate at the REGEN OUT port of the Dionex ACRS-ICE 500. For the example isocratic applications, this flow rate should be 3 - 5 mL/min.
B. Check the eluent flow rate. For most applications, the eluent flow rate should be 0.8
mL/min. Refer to the Dionex ACRS-ICE 500 Product Manual (Document No. 032661)
to ensure that the eluent concentration is within suppressible limits of the suppressor.
C. The suppressor may be contaminated. Prepare fresh regenerant solution. If the
background conductivity is high after preparing fresh regenerant, you probably need to
clean or replace your suppressor. Refer to the Dionex Anion Chemically Regenerated
Suppressor for ICE (Dionex ACRS-ICE 500) Product Manual” (Document No. 032661)
for assistance.
6 – Troubleshooting
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6.3 Poor Peak Resolution
Poor peak resolution can be due to any or all of the following factors.
6.3.1 Loss of Column Efficiency
A. Check to see if headspace in the analytical column. This may be due to improper use of
the column such as submitting it to high pressures. Remove the column’s top end fitting
(see Section 6.1.2, “Replacing Column Bed Support Assemblies”). If the resin does not
fill the column body all the way to the top, it means that the resin bed has collapsed,
creating a headspace. 1 - 2 mm of headspace is the maximum allowable before the
column demonstrates significant losses of efficiency. If more than 2 mm of headspace is
observed, the column must be replaced.
B. Extra-column system effects can result in sample band dispersion, decreasing peak
efficiencies. Ensure you are using PEEK tubing with an ID of no greater than 0.010" to
make all eluent liquid line connections between the injection valve and the detector cell
inlet on 4-mm systems. Check for leaks.
6.3.2 Poor Resolution Due to Shortened Retention Times
Even with adequate system and column efficiency, resolution of peaks will be compromised if
analytes elute too fast.
A. Check the eluent flow rate. See if it is different than the flow rate specified by the
analytical protocol. Measure the eluent flow rate after the column using a stopwatch and
graduated cylinder. Wait at least 5 minutes before making the measurement to allow time for the pump pressure feedback to engage.
B. Check to see if the eluent compositions and concentrations are correct. For isocratic
analysis, an eluent that is too strong will cause the peaks to elute later. Prepare fresh
eluent. If you are using a gradient pump to proportion the final eluent from concentrated
eluents in two or three different eluent reservoirs, the composition of the final eluent may
not be accurate enough for the application. Use one reservoir containing the correct eluent composition to see if this is the problem. This may be a problem when one of the
proportioned eluents is less than 5%.
C. Column contamination can lead to a loss of column efficiency. Cationic contamination
nonionic contamination or metal ions might be concentrating on the column. Refer to,
“Column Cleanup” (see Column Care in Appendix A) for recommended column cleanup
procedures. Possible sources of column contamination are impurities in chemicals, impurities
in the deionized water, or impurities from the sample matrix being used. Ensure the
recommended chemicals are used. The deionized water should have a specific resistance
of at least 18.2 megohm-cm.
D. If run times are reduced to the point that resolution is lost, clean the column (see,
“Column Cleanup” in “Column Care” in Appendix A). After cleaning the column, reinstall it in the system and let it equilibrate with eluent for about 30 minutes. The
column is equilibrated when consecutive injections of the standard give reproducible
retention times. The original column capacity should be restored by this treatment, since
the contaminants should be eluted from the column. If you need assistance in solving
resolution problems, contact Technical Support for Dionex Products. In the U.S., call 1-
800-346-6390. Outside the U.S., contact the nearest Thermo Fisher Scientific office.
6 – Troubleshooting
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6.3.3 Loss of Front End Resolution
If poor resolutions and efficiencies are observed for the very early eluting peaks near the system
void volume compared to the later eluting peaks, check the following:
A. Improper eluent concentration may be the problem. Remake the eluent as required for
your application. Ensure that the water and chemicals used are of the required purity.
B. Column overloading may be the problem. Reduce the amount of sample ions being
injected onto the analytical column by either diluting the sample or injecting a smaller
volume onto the column.
C. Sluggish operation of the injection valve may be the problem. Check the air pressure and
make sure there are no gas leaks or partially plugged port faces. Refer to the valve manual
for instructions.
D. Improperly swept out volumes anywhere in the system prior to the guard and analytical
columns may be the problem. Swap components, one at a time, in the system prior to the
analytical column and test for front-end resolution after every system change.
6.4 Spurious Peaks
A. Column fouling may be the problem. If the samples contain an appreciable level of aromatic weak acids or fatty acids (larger than 6 carbons) and the column is used with a
weak eluent system, these anions may contaminate the analytical column. The retention
times for the analytes will then decrease and spurious, inefficient (broad) peaks can show
up at unexpected times. Clean the column as indicated in “Column Cleanup” (see
Column Care in Appendix A).
B. If you need assistance in determining the best way to clean strongly retained solutes in your specific sample matrix from the Dionex IonPac ICE-AS1 columns, contact
Technical Support for Dionex Products. In the U.S., call 1-800-346-6390. Outside the
U.S., contact the nearest Thermo Fisher Scientific office.
C. Baseline disturbances may be caused when an injection valve is actuated. This baseline
upset can show up as a peak of varying size and shape. It will happen when the
injection valve needs to be cleaned or serviced (see the IC system). Check to see that there are no restrictions in the tubing connected to the valve. Also check the valve port
faces for blockage and replace them if necessary. Refer to the IC system manual for
troubleshooting and service procedures. Small baseline disturbances at the beginning or
at the end of the chromatogram can be overlooked as long as they do not interfere with
the quantification of the peaks of interest.
If cleaning and servicing the valve does not help, replace the valve. Consult the
accompanying manual for service instructions.
D. When doing trace analysis with solvents in the eluent, a solvent peak will appear around
the total exclusion volume of the column. This occurs at 12-15 minutes after injection
when operating at a flow rate of 1.0 mL/min. This is a suppressor phenomenon that can
be avoided by making the solvent concentration of the sample the same as the solvent
concentration of the eluent.
6 – Troubleshooting
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6.5 Split Peaks
Split Peaks are Low Sample Concentrations. A high sample pH can cause peak splitting. This
problem can occur for early eluting peaks such as citrate at concentrations below 1 mg/L (1 ppm).
If you observe split peaks, adjust the pH of the sample to less than pH 3-4 using acids (e.g.,
hydrochloric or sulfuric acid), or pass the sample through a Dionex OnGuard™ II H cartridge
(P/N 057085). If you have a Dionex AS-DV autosampler, you can load samples into 5 mL Dionex
PolyVials (P/N 038008) fitted with 5 mL Dionex GuardcapTM H vial caps (P/N 302504) to
reduce sample pH. See the Dionex OnGuard II cartridges product manual (Document No.
031688) or the Dionex Guardcap H product manual (Document No. 065705) for more
information.
Appendix A – Column Care
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Appendix A – Column Care
A.1 Recommended Operation Pressures
Operating a column above its recommended pressure limit can cause irreversible loss of column performance. The maximum recommended operating pressure for Dionex IonPac ICE-AS1
columns is 1,000 psi (6.90 MPa).
A.2 Column Start-Up
The column is shipped in eluent (1.0 mM acid) storage solution.
Pump fresh eluent through the column with the column disconnected from the suppressor
for about 20 minutes to clean out any polymer leach from the resin. Simply run effluent
into a beaker. You will notice an initial brown color, which should turn clear within a few
minutes. Repeat this process if the column is unused for longer than a week. This will
prevent damage to the suppressor.
Prepare the eluent shown on the test chromatogram, install the column in the chromatography
module and test the column performance under the conditions described in the test chromatogram.
Continue making injections of the test standard until consecutive injections of the standard give
reproducible retention times. Equilibration is complete when consecutive injections of the
standard give reproducible retention times.
It is important to maintain a constant temperature for reproducibility. The Dionex IonPac
ICE-AS1 is tested at 19 ± 1OC. If the column is exposed to temperature variations of 5O C
or more, selectivity changes may be observed.
A.3 Column Storage
For both short-term storage and long-term storage, eluent (1.0 mM acid) should be used as the
storage solution. Flush the column for a minimum of 10 minutes with the storage soluton. Cap
both ends securely, using the plugs supplied with the column. When putting the column back into service after storing it, pump fresh eluent through the column with the column disconnected from
the suppressor for about 20 minutes to clean out any polymer leach from the resin. Polymer leach
from the column can severely contaminate the suppressor.
A.4 Column Cleanup
The following column cleanup protocols have been divided into three general isocratic protocols
to remove acid-soluble, base-soluble or organic contaminants. They can be combined into one
gradient protocol if desired but the following precautions should be observed.
Always ensure that the cleanup protocol used does not switch between eluents which may create
high pressure eluent interface zones in the column. High pressure zones can disrupt the uniformity
of the packing of the column bed and irreversibly damage the performance of the column. High pressure zones in the column can be created by pumping successive eluents through the column
CAUTION
!
NOTE
!
Appendix A – Column Care
Thermo Scientific Product Manual for Dionex IonPac ICE-AS1 Column Page 52 of 52 031181-07 For Research Use Only. Not for use in diagnostic procedures.
that are not miscible. The precipitation of the salts in solvents during column rinses can result in
very high pressure zones. High viscosity mixing zones can be created between two eluents having
solvents with a very high energy of mixing.
When in doubt, always include short column rinse steps to reduce the solvent content of the eluent
to 5% levels and the ionic strength of the eluent to 5 mM levels to avoid creating high pressure
zones in the column that may disrupt the uniformity of the column packing.
A.5 Choosing the Appropriate Cleanup Solution
A. Iron contamination of the Dionex IonPac ICE-AS1 results in a decease in peak heights.
However, successive injections of citrate samples will remove the iron resulting in
increasing peak heights.
B. Citric acid solutions in the concentration range of 2 to 5 mM will remove a variety of metals. If after citric acid treatment, the chromatography still suggests metal
contamination, treatment with chelating acids such as oxalic acid in the same
concentration ranges is recommended.
C. Organic solvents can be used if the contamination is nonionic and hydrophobic. The
degree of nonpolar character of the solvent should be increased as the degree of
hydrophobicity of the contamination within the range of acceptable solvents listed in Table 4, "HPLC Solvents for Use with Dionex IonPac ICE-AS1 Columns" in the manual.
D. Acid solutions such as 5 to 10 mM HCl can be used with compatible organic solvents to
remove contamination that is ionic and hydrophobic. The acid suppresses ionization and
ion exchange interactions of the contamination with the resin. The organic solvent then
removes the subsequent nonionic and hydrophobic contamination. See Section B above.
E. A frequently used cleanup solution is 5 mM heptafluorobutyric acid in 10% acetonitrile.
This solution must be made immediately before use because the acetonitrile will
decompose in the acid solution during long term storage. Regardless of the cleanup
solution chosen, use the following cleanup procedure in "Column Cleanup Procedure",
to clean the Dionex IonPac ICE-AS1.
A.6 Column Cleanup Procedure
A. Prepare a 500 mL solution of cleanup solution. Select the solution using the "Choosing
the Appropriate Cleanup Solution" guidelines.
B. Disconnect the suppressor from the Dionex IonPac ICE-AS1 Analytical Column.
Connect the Dionex IonPac ICE-AS1 directly to the pump. Double check that the eluent
flows in the direction designated on the column label. Direct the effluent from the outlet line of the Dionex IonPac ICE-AS1 to a separate waste container.
C. Set the pump flow rate to 0.50 mL/min. for 9 mm columns or 0.1 mL/min for 4 mm
columns.
D. Pump the cleanup solution through the column for 60 minutes.
E. If your cleanup solution contains a solvent between 10 and 15%, use a gradual gradient
which reaches a maximum solvent concentration after 30 minutes. Wash the column for 30 minutes and then ramp back down to the eluent over 15 to 30 minutes.
F. Reconnect the suppressor to the Dionex IonPac ICE-AS1 Analytical Column and
connect the Dionex IonPac ICE-AS1 to the injection valve.
G. Equilibrate the Dionex IonPac ICE-AS1 with eluent for 30 minutes before resuming
normal operation.