Calibration of mercury analysers: assessment of agreement between four methods

Abstract

Various procedures for the calibration of mercury (Hg) analyzers have been developed to accumulate reliable and accurate information on the emission of Hg pollutants. However, there are no reports verifying an agreement between each procedure. Therefore, for the first time, this study assessed the agreement between the following four different Hg calibration methods: (1) temperature-controlled vapor pressure of Hg, (2) permeation tube, (3) known-concentration of Hg solution, and (4) absorption coefficient of Hg⁰ at 253.7 nm light with a known-length of gas cell of Beer's law. Methods (1) and (3) showed similar signal intensities, whereas methods (2) and (4) gave completely different values compared to methods (1) and (3). These experimental observations suggest that great care must be taken when calibrating a Hg analyzer. We have also recommended using methods (1) and (3) for the calibration of a Hg⁰ analyzer.