Elemental Analysis using next generation plasma spectroscopy · 2016-09-11 · 1 Elemental Analysis...

April 22, 2014

Confidentiality Label

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Elemental Analysis using next generation plasma spectroscopy

April 22, 2014


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Agenda

• Routine elemental spectroscopy over the last 50 years

• Common challenges facing routine elemental spectroscopy

• R&D to address challenges

• How does the MP-AES work?

• Analytical performance and applications.

April 22, 2014


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Routine Elemental Analysis over last 50 yrs

• Routine = 5-10 elements. 100-200 samples per day. Mid ppb

to ppm concentration range.

Sample

Ground State Excited State

Flame Graphite Furnace

Or

Monochromator

&Detector

Quantitation

Lamp

Hollow Cathode Lamp

(HCL)

Electrode-Less Discharge

Lamp (EDL)

AAS

April 22, 2014


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Agenda






April 22, 2014


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Common challenges facing Labs doing elemental analysis

• Increased need for multi-element determination over a wide dynamic range

• Desire to reduce the overall cost of analysis due to rising costs (instrument supplies and consumables – power, labor, etc)

• Some laboratories under pressure to improve safety by removing flammable gases

• Difficulty in sourcing some gases – especially in remote areas and emerging geographies

• Availability of suitably trained personnel to develop methods, perform sample measurement and interpret results

April 22, 2014


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Agenda






April 22, 2014


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Early Research in Microwave Plasma

• 1976 – review of MP of research by Skogerboe and Coleman.

• Analytical Chemistry, Vol 48. No. 7, June 1976

- CMP – capacitively coupled microwave plasma (requires conductive

electrode)

- MIP – Microwave induced plasma (electrodeless)

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Early research conclusion

• CMP was better suited for elemental analysis

• Sample is introduced from peripheral boundary of the plasma. This lead

to analytical problems.

• MIP was better suited as an atomization/ionization

source for GC

• Could not handle lots of liquid as the plasma would extinguish.

• CONCLUSION: “Plasmas produced with low power

microwave supplies show considerable promise as spectral

excitation sources.”

April 22, 2014


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MP-AES technology research at Agilent

• CMP and MIP systems not adequate for routine elemental

spectroscopy - needs new approach.

• Used axial magnetic and radial electric field from microwave

source to sustain plasma.

Senior Research Engineer:

Michael Hammer

Senior Development Engineer:

Hugh Stevenson

April 22, 2014


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Award winning MP-AES

2013 AIRG medal

2012 R&D 100

April 22, 2014


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Agenda






Ground State Excited State Relaxation

Sample

Microwave excited

Plasma

Monochromator

& Detector

Quantitation

Atom Formation

EXCITATION

Emission

Microwave Plasma Emission Overview

MP-AES

How does the MP-AES work?

• 4200 MP-AES runs on nitrogen extracted from air using the Agilent 4107 nitrogen generator

• Axial magnetic and radial electrical fields sustain the nitrogen plasma

• Sample aerosol is introduced into nitrogen plasma.

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How does the MP-AES work?

• Axial emission from the vertical oriented nitrogen plasma is

directed into the fast scanning monochromator optics

• Wavelength specific emissions are detected using a high

efficiency CCD.

April 22, 2014

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Technique Comparison: MP-AES and Flame AA

Feature

Detection Limits

Linear Dynamic Range

Flammable Gas

Oxidizing Gas

Fuel gas CO2

Light sources

Drift correction

Overnight unattended

Running costs

MP-AES

Better

Better

Not Required

Not Required

Not Required

Not required

Not required

Yes

Lowest

Flame AA

Good

Good

Acetylene

Nitrous oxide

1 – 6 tonnes p.a.

HC and D2 lamps

Double beam

No

High

Higher Performance

• Ideal flame AA alternative

• Handles major, minor & most trace levels

• Wider linear dynamic range

• Lower detection limits

Easy Operation

• New generation software

• Simultaneous auto background correction

• Plug & Play torch

Safer Laboratory Operation

• No flammable gases

• Unattended multi-element operation

Key benefits of MP-AES

Lowest cost of ownership

• Runs on air!

• Eliminates on-going gas supply costs

Low cost of ownership

April 22, 2014

Agilent Confidential

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• Supply of gases is the major on going cost for any routine

elemental spectrometer.

• 4200 MP-AES uses nitrogen extracted from air using Agilent

4107 nitrogen generator.

• Example, big USA fruit juice manufacturer doing 100 FAAS

samples per day, 3 elements per sample.

Online cost estimator available at:

http://www.chem.agilent.com/en-

US/products-services/Instruments-

Systems/Atomic-

Spectroscopy/Pages/mpaes-

estimator.aspx

http://www.chem.agilent.com/en-US/products-services/Instruments-Systems/Atomic-Spectroscopy/Pages/mpaes-estimator.aspx












Safety

April 22, 2014

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• Using inert nitrogen gas to sustain the

atomization/ionization source eliminates

the need to use combustible gases like

acetylene.

• Not having to ever replace a gas cylinder

reduces manual handling issues.

3 sigma DLs using a 10 second integration time with dewar nitrogen

Element Flame AA 4200MP-

AES

K 0.8 0.65

Ca 0.4 0.04

Mg 0.3 0.09

Na 0.3 0.12

Au 5 2.1

Pt 76 6.1

Pd 15 1.6

Ag 1.7 1.2

Rh 4 0.5

DL’s in ppb, clean water samples

4200 MP-AES Performance – Detection Limits

Element Flame AA 4200 MP-

AES

As* 60 57

Cd 1.5 1.4

Cr 5 0.3

Mn 1.0 1.05

Pb 14 2.5

Sb 37 12

Se* 500 77

Zn 1.6 3.1

* 30 second integration time used for these elements

Ease of use– reduced sample preparation

Optimum working range

comparison between FAAS

and MP-AES:

April 22, 2014

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Element 4200 MP-AES,

mg/L

Linear correlation

coef. MP-AES

FAAS, mg/L

Au 242.8 0.05 – 50 0.9999 0.1 – 30

Ca 422.6 0.01 – 20 0.9999 0.01-10

Mg 518.3 0.05 – 100 0.99988 0.15-20 (202.6nm)

Na 589.5 0.01 – 20 0.99996 0.01-2

K 767.8 0.05 – 100 0.99968 1-6

Example: Au 242.8nm calibration for 4200 MP-AES

Ease of Use

Simple hardware

• Torch installation

• Sample Introduction System

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Ease of Use

Simple software

• Applet quick start methods

• Auto optimization tools

• FLIC and IEC tools

April 22, 2014

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Ease of Use - MP-AES verses FAAS

• Simple sample preparation

- Reduced chemical and ionization interferences minimizes need for

addition of extra reagents

• Lower costs, higher sample throughput

• Reduces introduction of possible contaminants

April 22, 2014

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April 22, 2014


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Agenda






Determination of major elements in copper alloys using the Agilent 4200 MP-AES

April 22, 2014

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Major elements in copper alloys by 4200 MP-AES

Copper alloy sample preparation:

1 g SRM drillings (3 different alloys) was digested in open test

tube (pyrex) digestion / 1.5 ml HNO3 and 4.5 ml HCl made to

50ml (2% TDS 50 x dilution).

For determination of Cu and Zn, the samples were diluted

further 1:50 (0.04% TDS, 2500 x dilution)

Calibration solutions were prepared from commercial bulk

standards.

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Analysis of brass and bronze – major elements Cu and Zn

These analysis results had Neb flow optimized on the diluted bronze sample

Note: Cu and Zn had different nebulizer flows after auto optimisation.

Element Certified value (%) Result with MP(%) Wavelengths

Aluminium Brass Cu 75.1 75.2 (100.1%) 219 nm

SRM 1118 Zn 21.9 22.3 (101.8%) 481 nm

Bronze Standard Cu 93.0 92.4 (99.4%) 219 nm

NBS C1117 Zn 6.8 6.8 (100%) 481 nm

Naval Brass Cu 65.0 65.9 (101.4%) 219 nm

NIST C1108 Zn 34.4 34.3 (99.7%) 481 nm

Determination of major, minor and trace elements in rice flour using the 4200 (MP-AES)

April 22, 2014

Sample Preparation NIES CRM 10c Rice Flour

• Digested in Milestone Ethos microwave using preloaded

method

• 0.5g in 7 mL of HNO3 and 1 mL H2O2

• Digested, cooled then diluted to 25 mL

• Final total dissolved solids of 2%

No further sample preparation required

No modifiers or ionization buffers required

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Results Method Detection Limits

Element/

Wavelengt

h (nm)

Ca

422.673

Cd

228.802

Cu

324.754

Fe

438.354

K

766.491

Mg

280.271

Mn

403.076

P

214.915

Zn

213.857

MDL

(mg/kg)

In soild

sample

0.10 0.16 0.05 0.44 3.0 0.06 0.05 13 0.15

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Excellent Detection Limits

• 2nd generation waveguide and torch handle the 2% matrix

• Standard, robust sample introduction setup

• High temperature plasma source (~5000K) improves

performance

Results CRM Recoveries

mg/kg in

solid

Ca

422.673

Cd

228.802

Cu

324.754

Fe

438.354

K

766.491

Mg

280.271

Mn

403.076

P

214.915

Zn

213.857

Mean 96.0 1.96 4.13 11.50 2700 1174 37.35 3139 22.02

SD 2.5 0.11 0.29 1.03 105 23 1.04 92 0.48

Certified

value 95 1.82 4.1 11.4 2750 1250 40.1 3350 23.1

2SD

certified 2 0.06 0.3 0.8 100 80 2.0 80 0.9

%

Recovery 101.0 107.7 100.8 100.9 98.2 93.9 93.1 93.7 95.3

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• Accurate determinations over a wide concentration range

• All in one sample measurement

Long Term Stability <3% RSD for all elements over 8 hours in 2% TDS

22 April 2014

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0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

0 33 66 99 132

No

rmalized

Co

nc.

No. of Samples

Ca 422.673 Cd 228.802 Cu 324.754 Fe 438.354 K 766.491

Mg 280.271 Mn 403.076 P 214.915 Zn 213.857

Combination of improved waveguide and torch, robust plasma

and sample introduction give excellent long term stability

Experiment Summary 4200 MP-AES is the ideal FAAS alternative

Improved Performance

• Increased working range

• Phosphorus


Reduced Running Costs

• Runs on Air!

• No modifiers

Increased safety

• No acetylene

• No nitrous oxide

Ease of Use

• MP Expert

• Simple sample prep

• No burner change over

22 April 2014

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Determination of major and minor elements in geological samples using the 4200 Microwave Plasma-Atomic Emission Spectrometer (MP-AES)

April 22, 2014

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Analytical challenges of analyzing geochemical samples

• Wide working range to cover major, minor and trace concentrations

• High levels of total dissolved solids, complex acid sample prep

• Spectral interferences due to emission line overlaps

• Varying sample composition

• Non-spectral interferences due to EIE

April 22, 2014

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Sample preparation

Two CRMs prepared

• GBM398-4 Low grade Cu/Pb/Zn with Laterite

• GBM908-14 Cu-Zn-Pb Sulphide Ore

Acid digestion

• HNO3-HCl-HClO4-HF four-acid ‘total’ digestion

Sample dilution

• 0.4 g nominal sample weight brought to 100 mL final volume with 30% HCl

Calibration standards

• All calibration standards in 6% HNO3 and 19% HCl

- No modifiers or ionization buffers required

- No further sample dilutions required

April 22, 2014

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Analyte line selection, and background and interference correction methods

April 22, 2014

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Element Wavelength (nm) Type Background Correction

Interference Correction Possible Interferences

Ni 305.082 Analyte FLIC La

Ag 328.068 Analyte Auto IEC Cu, Ti

Ti 334.940 IEC element Auto x x

Pb 405.781 Analyte FLIC La and Ti

Zn 481.053 Analyte FLIC La, Sr, and Ti

Cu 510.554 Analyte FLIC Al2O3, and La

Lu 547.669 Internal standard FLIC Ni, Ti

• Wavelengths were selected to minimize spectral interferences and have

widest dynamic range

• All calibration curves are linear with correlation coefficient >0.999 and

<10% calibration fit error

• Lu internal standard was 10 ppm and delivered via Y-connector to the

sample tubing

Table 2. The emission line selection, background and interference correction methods

Spectral interference correction – Fast Linear Interference Correction (FLIC)

April 22, 2014

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Nickel and Ti interference on Lu 547.669nm line in FLIC

(background: blue, Lu; red, Ni: green, and Ti: dark blue)

Anayte (nm) Blank Analyte

mg/L

Interferent-1 Interferent-2 Interferent-3 Interferent-4 Interferent-5

Al mg/L Ti mg/L La mg/L Sr mg/L Ni mg/L

Ni (305.083) Cal Blank 10 x x 100 x x

Zn (481.053) Cal Blank 10 x 100 100 100 x

Cu (510.554) Cal Blank 10 1000 x 100 x x

Lu (547.669) Cal Blank 10 x 100 x x 100

Extra interference models can be added, even after results have been collected.

Table 3. FLIC sequence

Spectral interference correction – Conventional IEC

IEC factors are developed using

intuitive MP Expert software.

IEC solutions used:

• 1 ppm Ag (analyte)

• 100 ppm Ti (interferent)

• 1000 ppm Cu (interferent)

These concentrations represent

the expected concentrations in the

sample.

April 22, 2014

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MP Expert IEC factors and Ag calibration

Results and discussion

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Reference MDL GBM398-4 GBM908-14

MP-AES Certified Recovery (%) MP-AES Certified Recovery (%)

Ag (mg/kg) 1 45.8 48.7 94 289.7 304.7 98

Cu (wt %) 0.002 0.37 0.39 95 2.30 2.37 97

Ni (wt %) 0.002 0.39 0.41 97 - Not reported -

Pb (wt %) 0.002 1.08 1.17 92 3.24 3.30 98

Zn (wt %) 0.002 0.50 0.51 98 4.24 4.27 99

All results are shown as results in the original sample.

Results demonstrate the ability of the 4200 MP-AES to:

• Measure Ag at low concentrations, with interferences corrected by IECs

• Achieve excellent recoveries across a wide concentration range (0.39% to

2.37% for Cu, and 0.51% to 4.27% for Zn)

• Determine all elements in a single sample preparation

Table 4. MP-AES and certified CRM results

Potential cost savings with the 4200 MP-AES

April 22, 2014

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This example is intended to help you compare the running costs &

savings of the MP-AES vs. flame AA. The applied formulas and

parameters are correct to the best of our knowledge, but we cannot

guarantee the results. Savings may vary depending on factors such

as local gas and electricity costs, operator costs, number and types

of elements. For this calculation operator labor costs were set to

US$25/hour and electricity costs were set to US$0.18 per kW.

Total savings of more than

US$150k over an 7 year

evaluation period.

• FAAS with air compressor and

1 year consumables

• MP-AES with air compressor,

SPS 3 and 1 year consumables

• 5 elements measured under

method conditions

• 350 samples per week

Experiment Summary The Agilent 4200 MP-AES is the ideal FAAS replacement.

Improved performance

• Increased linear working range


Reduced running costs

• Runs on air

Increased safety

• No acetylene

• No nitrous oxide

Ease of use

• MP Expert

• IEC and FLIC

• Simple sample prep

April 22, 2014

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Conclusions

The 4200 MP-AES is the second generation of proven MP-AES technology, and is an ideal alternative (upgrade) for flame AA.

• MP-AES offers safe, cost effective elemental analysis, and is an ideal tool for routine beverage, food, and geochemical sample analysis

• QUESTIONS

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Elemental Analysis using next generation plasma spectroscopy · 2016-09-11 · 1 Elemental Analysis...

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