Why do you want to make pure elemental Se as the final Se product, it would be nice and easy to do Se by ICPMS or ICPOES.

I would digest an organic sample in acid, as an alternative you could measure the Se without digesting the amino acid first. It would be best if you tested the ICP method using the selenium amino acid first to determine if the machine is equally sensitive to Se in the organic form as it is to Se as an inorganic form.

Hi Mark,  thanks for that. Unfortunately I do not have ICPMS available to me so while it would be easy it is not an option. I have used ICPMS before when analysing TiO2 nanoparticles and it did give excellent results. My detection methods are via AAS analysis. My Se containing amino acids are  compared to a pure Selenium standard so I have to break down the above in order to  give a true comparison (molar ratios etc). I have found a nice technique involving nitric acid which seems to be working well. With the AAS instrument it is important not to use the undigested amino acids  as it affect the sensitivity of the analysis and clogs the instrument.