The world leader in serving science

Terri Christison, Carl Fisher and Jeff Rohrer

Thermo Fisher Scientific, Sunnyvale, CA, USA

Using electrospray ionization mass spectrometry as an ion chromatography confirmation tool for the determination of alkylamines and alkanolamines in scrubbing solutions

2

• Significant energy source, 21.6% of the total energy consumed in 2015

• Used as fuels, to generate electricity, and as raw material stock1

• Hydraulic fracturing has opened previously inaccessible shale deposits

• Changed producer rankings

• Changed the mix of gas entering the refineries

• Many of these wells contain sour gas (> 5.7 mg/m3 of H2S)

• Amine-rich scrubber solutions neutralize the sour gas into sweet gas2,3

Natural Gas Industry Background

1) https://www.iea.org/publications/freepublications/publication/KeyWorld2017.pdf

2) https://hub.globalccsinstitute.com/publications/final-report-project-pioneer/amine-scrubbing-process

3) http://naturalgas.org/naturalgas/processing-ng/

https://www.iea.org/publications/freepublications/publication/KeyWorld2017.pdfhttp://naturalgas.org/naturalgas/processing-ng/

3

Amine Scrubbing (Neutralizing) Process

Samples:

• 20-30% MEA, DEA or MDEA,

with organic acids, oxidized

sulfur species, inorganic

cations and anions

• Diluted 1000-fold with

analytical focus on

ammonium, sodium and

alkanolamine concentrations

http://www.enggcyclopedia.com/2011/05/amine-treating-unit/

https://en.wikipedia.org/wiki/Sulfur#Modern_times

https://en.wikipedia.org/wiki/Claus_process#/media/File:AlbertaSulfurAtVancouverBC.jpg

H2S(g) + 2R-NH-OH => 2H2O + S2- + 2R-NH=> SO3

2- => SO42-

CO2(g) + 2R-NH-OH => 2H2O + H2CO3 HCO3- CO3

2- => R-CO2- Na+

2H2S(g) + 3O2 => 2SO2 + 2H2O

SO2 + 2H2S(g) => 3S0 + 2H2O

4

Project Challenges

• Large sensitivity requirements

• From ppb to percent concentration

• High salt content in alkanolamine solutions used to neutralize sour gas

• Disparate concentrations in scrubbing amine sample

• Optimize MS for low-mass cations and amines

5

IC-MS

• Increases analytical confidence

• Provides sensitive detection and mass confirmation in addition to retention time often without the

need for sample pre-treatment

Single Quadrupole MS

•Higher sensitivity and more accurate quantitation than conductivity detection

•Chromatographic peak mass confirmation

• Eliminate false negatives and false positives

Why use IC-MS?

6

Flow Diagram for IC-MS

Dionex EGC

500 cartridge

Dionex

Degas

Module

Fresh 18 MΩ-cm

Resistivity

Deionized Water

Dionex

CR-TC

600 trap

Pump

CD

IC Diverter

Valve in

Position A

Autosampler

Thermo Scientific™ ISQ™ EC Mass

Spectrometer

Injection

Valve

SRD-10

Thermo Scientific™ Chromeleon™ Chromatography Data System (CDS)

AXP

Pump

Waste

Jumper

P

CL

LS

W4

12

3

5

6

P

C

L

LS

W

Thermo Scientific™

Dionex™ CERS™ 500e

Suppressor

Thermo Scientific™

Dionex™ Suppressor

Regenerant Detector

Thermo Scientific™ Dionex™

IonPac™ Columns

7

Dionex Integrion High-Pressure Ion Chromatography System

Automated monitoring of performance for all

consumables

Detachable tablet with IC controls in local

language

Simplified plumbing layout and easy-to-

install Thermo Scientific™ Dionex™ IC PEEK

Viper™ Fittings

Versatile system with flexible detector

options can be tailored to meet future needs

Faster analysis without compromising data

quality using high-pressure IC

Better method reproducibility using

Automated Eluent Generation

8

Methanesulfonic Acid Eluent Generation for Cation Analysis

[-] Pt anode

(H2O 2H+ + ½O2 + 2e

-)

Anion-exchange connectorMSA

Generation Chamber

Vent

Pump

H2O

Pt [+] cathode

(2H2O + 2e- 2OH- + H2)

[MSA]Current

Flow rate

MSA + O2 MSA

O2

MSA-ElectrolyteReservoir

MSA

DegasUnit

CR-CTCCation Trap

• Easy set-up and no need to prepare manual eluents

• Elimination of acid and base handling

• Longer-lasting pumps because they encounter only deionized water

9

Suppressed Conductivity Results in Increased Signal/Noise Sensitivity

Li+

Time

µS

Without Suppression

Time

µS

With Suppression

Methanesulfonic acid eluent

(MSA) Sample Li+, Na+, Ca2+

Ion-Exchange

Separation Column

Cation Electrolytically

Regenerating

Suppressor

in H2O

Li-MSA, Na-MSA, Ca-(MSA)2

in MSA

Injection Valve

Counter ions

LiOH, NaOH, Ca(OH)2

Na+ Ca2+

Li+

Na+ Ca2+

10

Thermo Scientific ISQ EC Single Quadrupole MS

Provides enhanced low mass performance

For ion and liquid

chromatographers

Mass range

10–1250 m/z

Controlled by Chromeleon

CDS and optional Chromeleon

XPS

Built for

routine

analysis

HESI II

for enhanced ionization +

AutoSpray

11

Instrument Specification Comparison with Predecessor

* SIM mode

Specification ISQ EC MSQ Plus

Mass Range (m/z) 10–1250 17–2000

Source Type ESI ESI / APCI

Supported Modes Full scan / SIM Full scan / SIM

ESI Max Flow Rate 2 mL/min 2 mL/min

Scan Rate, max (Da/s) 20,000 12,000

SIM Sensitivity (ESI+)10 pg reserpine

400:1 RMS

50 pg erythromycin

1,000:1

Polarity Switching Yes, 25 ms Yes, 240 ms

Mass Resolution Unit (≤ 1.0 Da) Unit (≤ 1.0 Da)

Mass Accuracy /

Stability

≤ ± 0.1 Da

≤ 0.1 Da over 24 h

≤ ± 0.3 Da

≤ 0.1 Da over 24 h

Digital Dynamic Range 107 104

Roughing Pump External oil-based rotary External oil-based rotary

Power 100-240 VAC 50/60Hz 240 VAC 50/60 Hz

Reserpine MDL* (pg) 0.3 1.0

Erythromycin MDL* (pg) 0.08 0.25

3x better

3x better

12

Electrospray Mechanism

Ion containing

droplets

Capillary

+5 kV

With droplet’s

evaporation progress,

field increases and ions

move towards surface

Once the Rayleigh

limit is reached a

coulombic

explosion

happens and

releases ions

13

HESI-II: Electrospray Ion Source as a Current-limited Electrolytic Cell

Power SupplyElectrophoretic

charge separationSource inlet

(counter electrode)

ESI Capillary

(working electrode)

Vacuum

Liquid-Gas Interface

14

ISQ EC Mass Spectrometer Ion Flight Path

Mass Analyzer

Ion

Source

Detector

15

Easy Mode for novice user, advanced

tools for MS experts

Autotune can be part of a sequence –automated calibration

Autospray™technology translates physical

properties into optimal method

parameters

Real-time scanning for online signal optimization

ISQ EC MS Control Embedded into Chromeleon CDS

16

Using the Chromeleon Instrument Method Wizard to Create IC-MS Methods

Scan and Acquisition Rate in Easy Mode

17

Translated into Component/Advanced Mode

18

Method Development: Scrubbing Amines

ColumnThermo Scientific™ Dionex™ IonPac™ CS19-4µm, 2 x 250 mm,

600 µEq/column (20-35 min)

Separation2.5 µL of sample; gradient separation: 4 mM to 60 mM from 0.1 to 27.5

min, 0.25 mL/min using electrolytically generated MSA

First DetectionSuppressed conductivity, Dionex CERS 500e Suppressor,

external water mode

Second Detection ESI MS with HESI-II probe, +3000V, full scan 18-250 m/z, SIM

Probe and MS Temperatures Vaporizer 250 C; Ion Transfer 250 C

Probe Nitrogen flow Sheath 50 psi, Aux 4 psi, Sweep 0.2 psi

Desolvation solvent none

• Need selectivity for alkanolamines

• Need high capacity to resolve µg/L concentrations from percent

concentration

19

SIM Table for Scrubbing Amines Method

Formula Isotopic (Accurate) Mass Ion m/z+1 CID (V)

Ammonium as NH4 NH3 17.027 18 10

Ammonium as NH4*H2O NH4*H2O 35.038 36 5

Calcium as Ca*2H2O Ca*2H2O 75.985 76 10

Dibutylamine C8H19N 129.152 130 10

Diethanolamine (DEA) C4H11NO2 105.079 106 20

Diethylamine C4H11N 73.089 74 15

Dimethylamine C2H7N 45.058 46 10

2-Dimethylaminoethanol C4H11NO 89.084 90 20

Ethanolamine (EA) C2H7NO 61.053 62 15

Ethylamine C2H7N 45.058 46 10

Hydrazine N2H4 32.037 33 10

Magnesium Mg 23.985 24 10

Magnesium as 2Mg*H2O 2Mg*H2O+ 65.981 66 10

Methylamine CH5N 31.042 32 10

Methylaminoethanol C3H9NO 75.068 76 10

Methyldiethanolamine (MDEA) C5H13O2N 119.095 120 10

Potassium K 38.964 39 10

Sodium as Na Na 22.990 23 10

Sodium as Na*2H2O+ Na*2H2O

+ 59.011 59 10

Triethanolamine (TEA) C6H15NO3 149.105 150 25

20

Optimizing Experiments to Evaluate the Stability of the Hydrate Ions

Sodium Ammonium DEA

Na+ Na-2H2O+ Total NH4

+ NH4-H2O+ Total

m/z 23 59 18 36 106

Mean

(cts-min)1.62E+3 1.26E+6 1.26E+6 92 3.98E+4 3.99E+4 1.23E+7

%RSD 1.5 2.6 2.6 4.9 1.9 1.9 1.8

Hydrated forms provide more response than bare ions

21

100 ppm Sodium and Ammonium in Methyldiethanolamine

Columns: Thermo Scientific™ Dionex™ IonPac™ CG19-4µm, 2 50 mm

Dionex IonPac CS19-4µm, 2 250 mm

MSA Gradient: 4 mM Methanesulfonic acid (MSA )(0–0.1 min), 4–60 mM

(0.1–27.5 min), 4 mM (27.6–35 min)

Eluent Source: Thermo Scientific™ Dionex™ EGC 500 MSA Eluent Generator

Cartridge, Thermo Scientific™ Dionex™ CR-CTC 600

Continuously Regenerated Cation Trap Column, Dionex high-

pressure degasser

Flow Rate: 0.25 mL/min

Injection Vol.: 2.5 µL

Column Temp.: 30 C

Detector 1: Suppressed conductivity, Thermo Scientific™ Dionex™

CERS 500e Cation Electrolytically Regenerated Suppressor,

48 mA, 30 ºC,

external water mode, 0.5 mL/min by Dionex AXP-MS pump

Detector 2: ISQ EC MS, +ESI, +3000 V source, HESI II

Scan mode: Full scan: 18-200 m/z, SIM

Sampling Rate: 15 s chromatography width, 10 points/peak

Make-up solvent: none

Source Temp.: Vaporizer 250 ºC , Ion Transfer 250 ºC

N2 Gas flow (psi): Sheath 50, Aux 4, Sweep 0.2

Standard: 1000-fold diluted methyldiethanolamine with added sodium

and ammonium

Peaks: CID (V) RT(min) Conc. (mg/L)

1. Sodium *2H2O 10 5.94 100

2. Ammonium *H2O 5 6.35 100

3. Diethanolamine 10 7.00 1000

4. Ethanolamine 10 6.51 ~ 2

5. Triethanolamine 10 7.53 ~ 2

Minutes

32

1180

-20

µS

4 100 2 6

4 5

CD

8

58.5-59.5

2.5e6 (Ct-

min)

SIM

Relative

Abund.

(Cts)

4.9 6.9

5.0e6

min

1

5.8e5

(Ct-min)

5.9 6.9min

2.5e5

35.5-36.5

2

2.0e7

(Ct-min)

105.5-106.5

5.6 9.5min

2.5e7 3

61.5-62.5

5.9 6.9

1.2e6

2.3e5

(Ct-min)

min

4

5.6 9.5min

149.5-150.5

6.0e5

2.6e5

(Ct-min)

5

22

Summary of Calibration and MDL Results

IonCalibration Range

(mg/L)Type

Coefficient of

Determination (r2)

MDL+

(µg/L)

Na*2H2O 0.040–20 Quadratic fit, 2nd order 0.9995 8++

NH4*H2O 0.0025–25Quadratic fit, 2nd order,

weighted 1/x0.9919 22++

EA 200–2000

Quadratic fit, 2nd order

0.9994 ND

DEA 200–3333 0.9971 ND

Potassium 0.005–50 0.9991 4+++

MDEA 200–3333 0.9984 ND

2Mg*H2O 0.025–25 0.9989 15++

Ca*2H2O 0.050–50 0.9962 64++++

+ MDL= 3x S/N, n = 7

ND: not determined

MDL Standard,

Dionex Combined Six Cation II standards: ++ 10,000-fold dilution +++ 50,000-fold dilution ++++ 5,000-fold dilution

Calibration linearity and ppb MDLs

23

Amines and Cations in 1000-fold Dilution of Different Scrubbing Amine Samples

Columns: Dionex IonPac CG19-4µm, 2 50 mm

Dionex IonPac CS19-4µm, 2 250 mm

MSA Gradient: 4 mM MSA (0–0.1 min), 4–60 mM (0.1–27.5 min),

4 mM (27.6–35 min)

Eluent Source: Dionex EGC 500 MSA Eluent Generator Cartridge, Dionex

CR-CTC 600 Trap Column, Dionex high pressure degasser

Flow Rate: 0.25 mL/min

Injection Vol.: 2.5 µL

Column Temp.: 30 C

Detector 1: Suppressed conductivity, Dionex

CERS 500e suppressor, 48 mA, 30 ºC,

external water mode, 0.5 mL/min by Dionex AXP-MS pump

Detector 2: ISQ EC MS, +ESI, +3000 V source, HESI II

Scan mode: Full scan: 18-200 m/z, SIM

Sampling Rate: 15 s chromatography width, 10 points/peak

Make-up solvent: none

Source Temp.: Vaporizer 250 ºC , Ion Transfer 250 ºC

N2 Gas flow (psi):Sheath 50, Aux 4, Sweep 0.2

CID (V): Ammonium: 5; EA: 15, DEA: 20, TEA: 25, all others: 10

Peaks: A B C (mg/L)

1. Sodium *2H2O

24

Summary of Recovery Experiments

Sodium hydrate

Na*2H2O

Ammonium hydrate

NH4*H2OAlkanolamine

SampleFound

(mg/L)

Added

(mg/L)

Recovery

(%)

Found

(mg/L)

Added

(mg/L)

Recovery

(%)

Found

(mg/L)

Added

(mg/L)

Recovery

(%)

EA -- 0.42 99.1 0.25 0.21 101.3 2100 762 89.4

DEA 0.27 0.96 102.0 0.095 1.3 104.0 220 1570 101.3

MDEA 0.003 0.63 103.5 0.39 0.93 101.9 310 971 99.4

Good method accuracy (89 - 104% recovery)

25

• Determined inorganic amines, alkylamines, and alkanolamines in scrubbing

amines by IC-MS

• ppb concentrations of ammonium and sodium (as hydrates) and concentrated

alkanolamines in same sample

• Advantages of IC-MS

• Higher sensitivity and accuracy than CD

• Chromatographic peak confirmation

• Eliminates false positives, false negatives

Conclusions

26

Resources

AN72609 TN72611

AppsLab.com

https://assets.thermofisher.com/TFS-Assets/CMD/Application-Notes/an-72609-ic-ms-alkanolamine-scrubbing-solutions-an72609-en.pdfhttps://assets.thermofisher.com/TFS-Assets/CMD/Technical-Notes/tn-72611-ic-ms-system-configuring-optimizing-tn72611-en.pdfhttps://appslab.thermofisher.com/

27

Online ISQ EC MS Resources

How to videos

Brochure

Blog

Application Methods

Specifications Sheet

28

The Thermo Scientific Dionex Ion Chromatography Product Line

RFIC

HPIC

Thermo Scientific™

Dionex™ Aquion™

IC System

Thermo Scientific™

Dionex™ Integrion™

HPIC™ System

Thermo Scientific™

Dionex™ ICS-4000

Capillary HPIC™ System

Thermo Scientific™ Dionex™

ICS-6000 Hybrid HPIC™ System

www.thermofisher.com/ic

29

Thank You!