I have a puzzle that hopefully someone can help me.
We have a need to determine sub ppb (ug/L in solution) of Hg in naphtha by ICP-OES.
While the peltier cooled Spray chamber on the ICP-OES will get us to about 5 ppb Hg, we need to think of digestion & pre-concentrate for aqueous hydride generation Hg determination to achieve the goal of sub ppb LOQ. (so the LOD needs to be < 0.2ppb).
I have thoughts of conc HNO3 attack on neat naphtha & then careful pre-concentration. I can see of sorts of problems like:
1 Would Conc HNO3 digest all the naphtha?
2 How to pre-concentrate the digested aqueous solution, without loss of Hg
maybe a closed vessel microwave oven will solve that ?
3 How to ensure oxiding state is not too strong to prevent NaBH4 (or SnCl2) reduction to enable reduction to Hg vapour.
There is insufficient need to justify a specific low level Hg analyser in petroleum ( like that supplied by PSA )