Abstract
Arsenic(III) and arsenic(V) species exist in sea water at concentration levels of less than 0.2 ng/ml to greater than 50 ng/ml. The concentration levels of these species in sea water are currently questionable due mostly to possible interferences. A reliable analytical method has been developed to separate and determine these species in sea water. The method involves the extraction of APDC-As(III) complex into a chloroform layer at a pH range of 4.0- 4.5. Wet ashing of the chloroform layer followed by reduction of arsenic(V) to arsenic(III) by potassium iodide makes it possible to determine arsenic by the atomic absorption spectrometry-hydride generation technique. The various parameters such as pH, percent APDC, interferences, efficient reducing agents and wet ashing methods have been investigated in this study. A detection limit of 0.031 ppb and a sensitivity of 0.140 ng/ml have been achieved. Precision as judged by % RSD (0.6-5.4) indicates good reproducibility of the results when synthetic sea water samples spiked with arsenic(III) and natural sea water samples are analyzed.
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