Evaluation of the influence of arsenical livestock drinking waters on total arsenic levels in cow’s raw milk from Argentinean dairy farms

The concentrations of total arsenic in cow’s raw milk and in the livestock drinking water were determined and compared, in order to establish the influence of natural arsenic levels in groundwaters on the final presence of arsenic in milk production of the most important dairy region in Argentina. A dry ashing procedure was used for the mineralisation of the milk samples. The total arsenic concentrations were determined by flow injection hydride generation atomic absorption spectrometry (FI-HGAAS). The mineralised milk samples and well water samples were pre-reduced with concentrated HCl and KI–C6H8O6 solutions. A volume of 500 μl of each solution of pre-treated sample was transported by a HCl 1.2 mol l−1 carrier solution at a flow rate of 11 ml min−1 and merged with a reducing NaBH4 0.2% (m/v) solution which flowed at 5.5 ml min−1. The hydride generated in a reaction coil was transported to the detector with a N2 flow of 100 ml min−1. The recovery values of added concentrations at levels of 2.5 μg l−1 and 5.0 μg l−1 of arsenic in milk were 103 ± 8% and 102 ± 6% for n = 3, respectively. The accuracy of the method for the determination of total arsenic in water was checked by analysis of a certified sample NIST 1643d. Detection limits were 0.7 μg l−1 and 0.6 μg l−1 for milk and well water, respectively. The results showed a low biological transference level of arsenic to the cow milk from the drinking water ingestion.