Determination of metals in animal tissues by potentiometric stripping analysis without chemical destruction of organic matter

Abstract

Metal (Cu, Pb, Cd) ions contents of various animal tissues have been determined by potentiometric stripping analysis (PSA) from lyophilized samples. The organic matter destruction, which is the classical preliminary step of such determinations, is circumvented by the use of sodium dodecylsulfate (DOC) and sodium desoxycholic acid (SDS) solutions, in a reflux process and with the aid of sonication. The efficiency of the digestion is tested by comparison with total mineralisation with the low temperature ashing (LTA) method. The digesting medium is adapted to PSA measurements by the aid of a mixed (aqueous-organic) electrolyte. Operating PSA parameters have been studied in the final medium to optimize analytical conditions in the goal of adapting the entire process for routine analysis in environmental control studies. The inherent advantages of a no-current electrochemical method are demonstrated. The process uses classical instrumentation and can be conducted, from the lyophilized sample, in approximately 3–4 h of operation. The relative standard deviation obtained by standard additions method is ±5% for Cd and Pb, and ±3% for copper. The study is conducted with various samples of heifer and fish livers obtained from the commercial distribution circuit and by fishing sampling.