Determination of mercury vapor in air using electrically heated, gold-coated wire-loops, in-torch vaporization sample introduction and inductively coupled plasma atomic emission spectrometry with photodiode array detection

Abstract

A method for the determination of Hg 0 vapor in ambient air using an electrically heated, Au-coated wire-loop, in-torch vaporization (ITV) sample introduction and inductively coupled plasma atomic emission spectrometry (ICP-AES) spectrometry with photodiode array detection is described. Tungsten wire-loops were coated with gold using sputtering methodology developed for scanning electron microscopy (SEM). Mecury vapor formed an amalgam with Au on the wire-loop, the wire-loop was inserted into a modified ICP torch about 10 cm below the plasma and electrical power was applied to the loop, thus thermally releasing mercury. Atomic emission was monitored using an ICP spectrometer equipped with a photodiode array detector. Calibration curves were constructed using a variation of the reduction-aeration method and were linear for about two-and-a-half orders of magnitude. Mercury vapor levels determined close to a polarography apparatus compared favorably with measurements taken at the same location using cold vapor atomic absorption spectrometry (CVAAS). The possibility of using a Au-coated wire-loop system as an integrating personal dosimeter is postulated.