Chemical Stability and Compatibility - Molybdenum and titanium stability; mercury volatility
Are Mo and Ti are stable for any length of time without using HF? Also, what is meant by the term "trace HF"? I also have a question about mercury (Hg).I've noticed that hot block digestions of a clean acid-water matrix with an inorganic mercury standard added to a final concentration of 0.5ug/L, result in mercury recoveries ranging from 75-80%. Is inorganic mercury is volatile enough to explain such a loss?
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Both Ti and Mo are stable in HCl. The lower in concentration you go, the better the chances of achieving solubility with any of the mineral acids. There is no set definition for trace HF. We consider anything less than 1000 ppm HF to be "trace HF." As for mercury stability, our experience with Hg is that it will readily adsorb onto plastic container walls at the ppb level in nitric acid. Therefore, the loss is likely after the digestion, i.e., after the digestate is transferred to a plastic container (some could be adsorbed at the sub ppb level during digestion in Teflon, glass or quartz). |