Freshly in situ prepared ferrite particles were used for the micro-solid phase extraction of arsenic species. When the separation was carried out at pH 8, inorganic arsenic (As(III) + As(V)) and monomethylarsonic acid (MMA) were retained in the magnetic material. A second aliquot was treated with 2,3 dimercapto propanol, leading to the retention of As(V)+MMA, while a third aliquot was first treated with sodium thiosulphate, in which case only inorganic arsenic passed to the solid phase. In all cases, the solid residue collected by a magnet was suspended in a dilute nitric acid solution containing Triton X-100 and introduced into the electrothermal atomizer to obtain the analytical signal of arsenic. The use of palladium as a chemical modifier allowed calibration to be carried out with aqueous standards. The detection limit was 0.02 µg L⁻¹ arsenic for a 10 mL sample volume. The procedure was applied to waters and herbal infusions, and its reliability was evaluated by analyzing eleven certified reference materials for which speciation data are provided.

新鲜的原位制备的铁氧体颗粒用于砷的微固相萃取。当在pH 8进行分离时，无机砷（As（III）+ As（V））和一甲基砷酸（MMA）保留在磁性材料中。第二等分试样用2,3二巯基丙醇处理，导致As（V）+ MMA保留，而第三等分试样先用硫代硫酸钠处理，在这种情况下，只有无机砷通过。在所有情况下，将磁铁收集的固体残留物悬浮在含有Triton X-100的稀硝酸溶液中，然后引入电热雾化器中以获得砷的分析信号。钯作为化学改性剂的使用允许使用水性标准液进行校准。检出限为0.02 µg L-10毫升样品体积的^-1砷。该程序适用于水和草药输液，其可靠性通过分析提供了形态数据的11种经过认证的参考材料进行了评估。