Abstract

Atomic fluorescence spectrometry (AFS) determination of Hg has been improved by exploiting the possibilities of the multicommutation approach in order to outline a fully mechanised system which supplies the same sensitivity as the use of continuous measurements, reducing drastically the reagents consumed and waste generation. The use of multicommutation with a simultaneous reduction of the liquid–gas separator volume and the insertion point modification of argon transport gas provides a sensitivity of the AFS measurements of 300 mV ng⁻¹ ml (using a full scale of 1000 mV), a limit of detection (3 s) of 1.3 ng l⁻¹ and relative standard deviation values below 0.1% for 10 independent measurements of a 0.6 µg l⁻¹ Hg solution. The Hg determination of one hundred samples could be carried out with 167 ml sample and 208 ml reagent mixture, as well as an argon consumption of 1450 ml and a waste generation of 375 ml. Thus, the sample and reagent consumption is reduced 6 times and the waste generation 2 times as compared with continuous measurements. Additionally, the sampling throughput increased from 13.5 h⁻¹ to 49.5 h⁻¹.