Development of a sequential injection system for trace mercury determination by cold vapour atomic absorption spectrometry utilizing an integrated gas–liquid separator/reactor

A simple and robust time-based on-line sequential injection system for trace mercury determination via cold vapour atomic absorption spectrometry (CVAAS), employing a new integrated gas–liquid separator (GLS), which in parallel operates as reactor, was developed. Sample and reductant are sequentially loaded into the GLS while an argon flow delivers the released mercury vapour through the atomic absorption cell. The proposed method is characterized by the ability of successfully managing variable sample volume up to 30 ml in order to achieve high sensitivity. For 20 ml sample volume, the sampling frequency is 25 h−1. The calibration curve is linear over the concentration range 0.05–5.0 μg l−1 of Hg(II), the detection limit is cL = 0.02 μg l−1, and the relative standard deviation is sr = 2.6% at 1.0 μg l−1 Hg(II) level. The performance of the proposed method was evaluated by analyzing certified reference material and applied to the analysis of natural waters and biological samples.