Determination of arsenic in dolomites with a simple field spectrometric device

A simple and an inexpensive procedure for the determination of total arsenic in dolomites is proposed. The method applies the spectrometric field device Supralab SD which was initially designed for the determination of arsenic in drinking water. The method relies on the formation of the volatile AsH3 and its reaction with mercuric bromide, immobilized in a membrane, to yield a yellowish-brown reaction product, which is spectrophotometrically detected. The dolomite samples were rapidly dissolved in hot hydrochloric acid in an open vessel and then were analyzed with the portable instrument. The 3 s detection limit of the developed method was 0.1 mu g L-1 as in the solution containing dissolved dolomites. The time of As determination in the solution did not exceed 5 min. To validate the results obtained with the field device, hydrogen generation inductively coupled plasma optical emission spectrometry (HG-ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS) were used as reference methods using microwave-assisted mineralization. Excellent agreement between the methods was obtained.