Here is what I do while analyzing Os.
1. Do not use HNO3, other than the health risk of OsO4, OsO4 is highly
volatile and gives false positive.
2. If I have to use digestion I use a thiourea stabilizer for Os, there is
a published article on this. I developed my method based on this.
3. Depending on compound, I use 2-5%HCl as the diluent, Os is stable in
4. I found Os loss occurs significantly if you go above the 80 degree C
even with closed vessel digestion. So I use high pressure. low temperature
and longer time for microwave digestion.
5. I soak the teflon sleeve of the digestion vessels in 100% acid and clean
them with MQ, this removes the absorbed particles from the sleeve- and
helps to retain appropriate temperature
6. I also use actual sample in the temperature monitoring vesel so that the
temperature during digestion does not go higher than the desired level.
7. I have recovery, which is better than the USP range.
Perhaps the best alternative is if you could use the organic diluent,
provided that you have the appropriate ICP-Ms parts.
On Mon, May 14, 2018 at 11:26 AM, Pappas, Richard Steve (CDC/ONDIEH/NCEH) <
[log in to unmask]> wrote:
> You are right about the loss of Os as due to formation of volatile OsO4.
> Ascorbic acid or cysteine added to a digestion vessel with nitric acid will
> only get the ascorbic acid and cysteine digested as well.
> I agree with what Robert Thomas said about checking the Inorganic Ventures
> web site regarding the use of alkaline nitrate fusion without HCl or KCl to
> prepare samples for Os or Ru analysis. However, in the Inorganic Ventures
> discussion, APDC (Ammonium pyrrolidinedithiocarbamate) is suggested. One
> must be aware that the longer APDC is in strong base, and the higher the
> temperature, the more APDC is decomposed as well, so experience plays a
> strong part in successful analysis.
> Tiene razón que la pérdida de Os está debido a la formación de OSO4
> volátiles. La adición de ácido ascórbico o de cisteína a un vessel de la
> digestión por ácido nítrico resultirá solamente en el ácido ascórbico y la
> cisteína también digerido.
> R. Steven Pappas, Ph.D.
> Team Lead, Tobacco Inorganics Group
> Centers for Disease Control & Prevention
> 4770 Buford Highway, NE
> M.S. F44, Building 110
> Atlanta, GA 30341-3717, USA
> -----Original Message-----
> From: PLASMACHEM-L: Analytical Chem.(ICP's, DCP's, MIP's). <
> [log in to unmask]> On Behalf Of Paqui Polonio
> Sent: Monday, May 14, 2018 9:52 AM
> To: [log in to unmask]
> Subject: Osmium stability analyses
> We are analyzing some samples of pharmaceutical industry. We are having
> bad recoveries in the analysis of osmium. After searching the possible
> problem, we have reach the conclusion that when we digest the sample the
> osmium reacts in the oxidizing media giving OsO4(g). In the literature are
> given some possible solutions to this problem. Stabilizing the osmium with
> a solution of ascorbic acid or cysteine.
> Does anyone use this to stabilize osmium? Wich concentration of ascorbic
> acir or cysteine should we use?
> Do you know any other possible solution to this problem?
> Thank you in advance.
> Paqui Polonio
> Lab. Echevarne
> Barcelona Spain
Boston Analytical Inc.
Email: [log in to unmask]
Direct: (603) 893-3758
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