On the determination of total mercury in natural gases using the amalgamation technique and cold vapour atomic absorption spectrometry

Studies on the use of noble metal collectors for the amalgamation of mercury from natural gas prior to thermal desorption and determination by cold vapour atomic absorption spectrometry have been performed. It is shown that collectors filled with gold/platinum wire are more efficient than those packed with gold or silver wire. Quantitative sampling efficiencies are obtained for Hg0 and (CH3)2Hg added to natural gas when the gold/platinum collector is heated to 80 °C, at sampling rates < 2 l min–1 and for volumes of at least 10 l. The precision for field measurements was established to be between 8 and 15% relative standard deviation, and the detection limit for the developed procedure is calculated to be 30 ng m–3 for a 10 l sample (3s criterion).