Cadmium losses on wet and dry ashing of plant materials

Cadmium losses on wet and dry ashing were studied using tomato leaves with metabolized¹⁰⁹Cd radiotracer. The most appreciable Cd losses (up to 35%) occured when sulphuric acid was used on wet ashing due to Cd retention in the CaSO₄ precipitate formed. Only trace amounts of Cd were retained in a silicaceous precipitate resulting from wet ashing in the absence of sulphuric and hydrofluoric acids in the decomposition mixtures employed. Small Cd losses (up to 7%) were observed on dry ashing in the air in open systems at temperatures not exceeding 500°C. Cd losses increased, however, to 30% when the final ashing temperature was raised to 900°C. Incorporation of the¹⁰⁹Cd radiotracer into various parts of tomato plants and its distribution between soil and the plants are also briefly reported.