A novel automatic method for the measurement of mercury vapour in ambient air, and comparison of uncertainty with established semi-automatic and manual methods

Abstract

The measurement of mercury vapour in ambient air is required in order to ensure the quality life of the general public. New legislation introduced recently by the European Commission has mandated that sampling and analysis be performed in situ at monitoring sites, and that mass concentration of mercury vapour in ambient air is determined within a maximum uncertainty. This paper presents a novel and innovative automatic method for such in situ measurements of mercury vapour in ambient air using atomic fluorescence spectrometry, where calibration, sampling and analysis are all performed fully automatically without manual intervention. A robust measurement equation and uncertainty budget for this automatic method is developed, and the overall relative expanded uncertainty for an exemplar measurement has been found to be 21%, well below the target expanded uncertainty of 50% set by the European Commission for these measurements. The uncertainty of a semi-automatic method (automatic sampling and analysis, but manual calibration) has also been assessed, and compared with the uncertainty of the novel automatic method, and the uncertainty of a manual (remote sampling and manual calibration and analysis) method presented in a previous study.