Analysis of Gold 995-999.9 ‰ using MP-AES 2015/S3_1_Bourgeois.pdf · LBMA PAM 4 995.29 4715...

transcript

LBMA Assaying & Refining Conference 2015 8-10 March 2015

Session 3 – Bourgeois 1

Analysis of Gold 995-999.9 ‰ using MP-AES

Thomas B. Jensen, Jean-Pascal Bourgeois1, Jonathan J. Jodry 1Jean-Pascal.Bourgeois@hefr.ch

Bridge between

research and industry

Process

Development

3 Axes of ChemTech

Synthesis

Scale-up

Production

Safety

Screening

Optimization

Analysis

Online monitoring

Surface characterization

CTI «strong franc» 2011

CHF 100 million (Euro 80 million) Over 1050 applications …for a total of CHF 500 million! 245 projects approved

The project «strong franc»

Agilent Technologies

ICP-OES vs. MP-AES

Inductively Coupled Plasma - Optical Emission Spectroscopy

Microwave Plasma - Atomic Emission Spectroscopy

Na Sr/Ca

ICP-OES vs. MP-AES

http://blog.labplanet.com

Emission plasma «N2»

As 188.979 nm

8 mg/L 6 4 2 0

As 188.979 nm

Linearity

Co 238.892 nm 0

0 20 40 60

Nominal

MP-AES

Co 238.892 nm

0 200 400 600 800 1000

Nominal

MP-AES

Linearity

Au 995+

Impurities quantification in Gold

• Max. total impurities : 5000 ppm

• Main impurities : Ag (0 – 5000 ppm)

• Other impurities : Cu, Pd, Pt, Fe, Ni, Pb, Sn, Zn…

Au 995+

• 200 mg Au 995+

• 4 mL aqua regia, 2 h, 70°

• 1 mL HCl (conc.), dilution → 10 mL

• Au concentration : 20 g/L

• 50 ppm → 1 mg/L

• 1 ppm → 0.02 mg/L

Au 995+

• Problem: precipitation of AgCl (s)

• Ag+ + Cl- → AgCl (s)

• Solution: addition de HCl

• AgCl (s) + Cl- → [AgCl2]-

Au 995+

Lines selection :

• Intensity (Ag, Cu)

• Interferences

Two lines for each element

Acquisition time:

• 3 s (Ag, Cu, Pd, Pt)

• 10 s (Fe, Ni, Pb, Sn, Zn)

3 replica

Au 995+

Detection Limit

Ag 520.907 3 Pt 265.945 0.9 Fe 259.940 0.9

Ag 546.549 1 Pt 299.796 0.5 Fe 373.486 0.8

Cu 510.458 0.4 Sn 303.412 0.8 Ni 305.082 0.2

Cu 510.554 0.2 Sn 326.234 0.5 Ni 349.295 0.1

Pd 340.458 0.2 Zn 213.857 0.6 Pb 368.346 0.2

Pd 342.124 0.2 Zn 472.215 0.5 Pb 405.781 0.1

Detection Limits (DL) based on blank experiments

Au 995+ ICP

(ppm) MP-AES (ppm)

ICP (ppm)

MP-AES (ppm)

Ag 520.907 2145.9 2120 ± 60 Fe 259.940 0.6 2.4 ± 3

Ag 546.549 2130 ± 10 Fe 373.486 21.3 ± 9

Cu 510.458 604.1 600 ± 10 Ni 305.082 0.3 2.6 ± 1

Cu 510.554 610 ± 9 Ni 349.295 1.6 ± 4

Pd 340.458 144.4 154 ± 9 Pb 368.346 0.1 4.1 ± 1

Pd 342.124 152 ± 10 Pb 405.781 0.6 ± 0.2

Pt 265.945 150.5 153 ± 2 Sn 303.412 0.7 3.3 ± 2

Pt 299.796 149 ± 4 Sn 326.234 6.5 ± 2

Zn 213.857 0.4 2.9 ± 10

Zn 472.215 1.8 ± 1

Total = 3047.0 3041 ± 35 o/oo 996.95 996.96

Au 995+

• DL underestimated by blank experiments

• To be on the safe side QL = 10 ppm

• Is it possible to qualify Au 999.9 ?

Gold matrix effect

Au 0 g/L

Au 20 g/L

Au 0 g/L

Au 20 g/L

Au 0 g/L

Au 20 g/L

Signal stability

Plasma perturbation: Ca, K, Na

Cu 60 mg/L Cu 52.6 mg/L (K 580 mg/L)

Cu 60 mg/L

Cu 52.6 mg/L (K 580 mg/L)

Avec soustraction de blanc

LBMA PAM samples

LBMA MP-AES

Au ‰

Total Impurities

Au ‰

Total Impurities

LBMA PAM 1 998.69 1310 998.69 1314

LBMA PAM 2 997.74 2265 997.78 2219

LBMA PAM 4 995.29 4715 995.29 4707

LBMA PAM 5 996.00 4000 996.09 3913

Conclusion

• MP-AES is a commercially available instrument

• Base line

• Detection/quantification limit

• Linearity

• Matrix effect: Ca, Na, K et ?

• Signal stability

Acknowledgements

• La commission pour la technologie

et l’innovation CTI

• Metalor Technologies

• Dr. Thomas Jensen

Analysis of Gold 995-999.9 ‰ using MP-AES 2015/S3_1_Bourgeois.pdf · LBMA PAM 4 995.29 4715...

Documents