Multicommutation cold vapour atomic fluorescence determination of Hg in water

A multicommutation-based method has been developed for the on-line direct atomic fluorescence spectrometric (AFS) determination of Hg in waters without any previous sample treatment. The performance of the proposed procedure has been compared with that of a conventional AFS system based on continuous mode measurements. In short, the use of multicommutation, together with a reduction of the size of the liquid-gas phase separator, provides an increase of the laboratory productivity by improving the sample throughput by a factor of 3.6 and strongly reduces the sample consumed by a factor of 6 and reagent consumed by a factor of 8.4. The waste generation is reduced by a factor of 2.4 and the Ar consumed by a factor of 6, thus the developed method is an environmentally and economically sustainable alternative to the methodology based on continuous measurements, without any reduction of the analytical sensitivity and with an enhancement of the repeatability of measurements. Only the limit of detection was poorer for the methodology developed (1.3 ngl(-1)) than that found by the classical continuous mode (0.3 ngl(-1)). The aforementioned methodologies were applied to the determination of Hg in water samples having obtained comparable values by both procedures and with those found by an external laboratory.