Wet Chemical Method for Gold-Silver Analysis by Atomic Absorption

Digestion and Silver Analysis

1. Use 150ml beakers cleaned with aqua-regia
2. Weigh 10g sample (top loading balance)
3. Wet with deionized water
4. Add 10ml HN03
5. Cover and heat for 15 minutes
6. Add 30ml HCl
7. Cover and heat for 20 minutes
8. Let cool
9. Bring to 100ml volume with 3N HCl
10. Stir with glass stirring rod (clean rod between each sample)
11. Let sediment settle and solution clarify

Ready for silver analysis by AA with background correction

Gold Analysis

12. Pour 50ml of left over solution into a graduated cylinder (avoid any sediment)
13. Pour into clean 250ml separatory funnel (Insure that stopcock is closed)
14. Add 10ml MIBK (Methyl Isobutyl Keytone)- Shake for 30 seconds
15. Let phases separate
16. Discard bottom layer into acid waste bottle
17. Add 50ml of 10% HCl - Shake for 15 seconds
18. Let separate
19. Discard bottom layer into acid waste bottle
20. Pour MIBK layer into clean, labeled test tube

Ready for gold analysis by flame or graphite furnace AA with background correction

(25Oct04)