Comparison of digestion methods for the determination of selenium in fish tissue by cathodic stripping voltammetry

A certified reference material (NIST-RM-50 Albacore Tuna) was analysed for selenium by cathodic stripping voltammetry (CSV), after digestion of the ma terial by a number of methods that avoid the use of perchloric acid. The di gestion techniques tested included wet and dry ashing methods, oxygen bomb digestion, ultraviolet (UV) digestion, and methods involving elevated press ure. The only method that reliably produced results that agreed with the certifi ed value for selenium in the reference material was the combination wet/dry ashing method incorporating elevated pressure recommended by the Associati on of Official Analytical Chemists (AOAC) for determination using hydride g eneration atomic absorption spectrometry (AAS). Recoveries using the other methods were low and variable, apparently because of incomplete destruction of organic matter and losses caused by volatilisation of selenium. (C) 200 0 Elsevier Science B.V. All rights reserved.