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 [email protected]
2
Bridge between
research and industry
LBMA Assaying & Refining Conference 2015 8-10 March 2015
Session 3 – Bourgeois 2
3
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
LBMA Assaying & Refining Conference 2015 8-10 March 2015
Session 3 – Bourgeois 3
The project «strong franc»
Agilent Technologies
ICP-OES vs. MP-AES
Inductively Coupled Plasma - Optical Emission Spectroscopy
Microwave Plasma - Atomic Emission Spectroscopy
Ca
Ba Cu
Na Sr/Ca
LBMA Assaying & Refining Conference 2015 8-10 March 2015
Session 3 – Bourgeois 4
ICP-OES vs. MP-AES
http://blog.labplanet.com
Emission plasma «N2»
Agilent Technologies
LBMA Assaying & Refining Conference 2015 8-10 March 2015
Session 3 – Bourgeois 5
Emission plasma «N2»
Agilent Technologies
As 188.979 nm
LBMA Assaying & Refining Conference 2015 8-10 March 2015
Session 3 – Bourgeois 6
8 mg/L 6 4 2 0
As 188.979 nm
Linearity
Co 238.892 nm 0
20
40
60
0 20 40 60
Measu
red
Nominal
ICP
MP-AES
mg/L
mg/L
LBMA Assaying & Refining Conference 2015 8-10 March 2015
Session 3 – Bourgeois 7
Co 238.892 nm
0
200
400
600
800
1000
0 200 400 600 800 1000
Me
as
ure
d
Nominal
ICP
MP-AES
mg/L
mg/L
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…
LBMA Assaying & Refining Conference 2015 8-10 March 2015
Session 3 – Bourgeois 8
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]-
LBMA Assaying & Refining Conference 2015 8-10 March 2015
Session 3 – Bourgeois 9
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
(ppm)
Detection Limit
(ppm)
Detection Limit
(ppm)
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
LBMA Assaying & Refining Conference 2015 8-10 March 2015
Session 3 – Bourgeois 10
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 ?
LBMA Assaying & Refining Conference 2015 8-10 March 2015
Session 3 – Bourgeois 11
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
LBMA Assaying & Refining Conference 2015 8-10 March 2015
Session 3 – Bourgeois 12
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 Assaying & Refining Conference 2015 8-10 March 2015
Session 3 – Bourgeois 13
LBMA PAM samples
LBMA MP-AES
Au ‰
Total Impurities
(ppm)
Au ‰
Total Impurities
(ppm)
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
LBMA Assaying & Refining Conference 2015 8-10 March 2015
Session 3 – Bourgeois 14
Acknowledgements
• La commission pour la technologie
et l’innovation CTI
• Metalor Technologies
• Dr. Thomas Jensen
