Nitric acid and hydrogen peroxide in the digestion of milk and cheeses for the detection of heavy metals

Abstract

The content of arsenic (As), cadmium (Cd), copper (Cu), chromium (Cr), lead (Pb) and zinc (Zn) in milk and cheeses was determined, comparing the use of nitric acid and a mixture of nitric acid and hydrogen peroxide (HNO₃ + H₂O₂) in acid digestion. The milk was collected from storage tanks in localities of Huejotzingo and cheeses in Santa Ana Xalmimilulco, Huejotzingo, Puebla. Digestion was carried out in a CEM MarsX microwave. The determination was in an ICP OES. As it showed (p <0.01) when using HNO₃ (0.13 mg kg^-1) with respect to the mixture. The Cd, Zn and Pb showed (p <0.01), with the use of the mixture with respect to HNO₃. The content of Cd, As, Cu and Cr in the cheese there was difference (p <0.01) when using HNO₃ compared to the mixture. This shows that there is specificity for metal detection, with HNO3 being the most efficient