Chemical Stability and Compatibility - Digesting an organic with Os Spike
Brian Alexander, PhD Total posts: 12
Through discussions and work with pharmaceutical and microwave manufacturers it is possible to obtain good Os recoveries for excipients and drug product analyses. The key appears to be mimimizing the HNO3 and using HCl in its place if and where possible. An example of a whole tablet microwave digestion that used the following procedure resulted in a 94% spike recovery for Os:
If you can avoid HNO3, or at least maximize the HCl/HNO3 ratio, then it should be possible to obtain adequate Os recoveries. You'll quickly know if OsO4 is forming as the volatility of the tetroxide results in very efficient nebulization/transport in the ICP sample introduction system, with the end result being very high Os signal intensities (i.e., extermely high recoveries). You can also mitigate OsO4 formation post-digestion by adding hydroxylamine hydrochloride to the samples, which will help prevent Os oxidation.