Evaluation of ammonia buffer containing EDTA as an extractant for Cr(VI) from solid samples

A novel procedure for the extraction of soluble, sparingly soluble and insoluble Cr(VI) from solid samples was presented. EDTA was added to an ammonia buffer commonly used only for the extraction of soluble and sparingly soluble Cr(VI). In the course of extraction in an ultrasonic bath cations which form insoluble chromates are complexed with EDTA while Cr(VI) is transferred to the solution. A concentration of EDTA equal to 0.01 mol L⁻¹ was chosen. The presence of EDTA in the extraction solution enables not only dissolution of insoluble Cr(VI) but also, as reported previously in literature, minimises oxidation of Cr(III) to Cr(VI). The extraction procedure was optimised and applied to Cr(VI) determination in the paint chips real sample. The results obtained were compared with the results obtained using two other extraction procedures. The results show that the novel extraction procedure can be used for the extraction of soluble, sparingly soluble and insoluble Cr(VI) from real solid samples.