Novel method to determine mercury in sediment using a gold coated dual ‘bent’ tube atom trap

Abstract

A dual ‘bent’ tube atom trap has been optimized for the detection of Hg by FAAS. A number of tube coatings were examined in an attempt to reduce the volatility of the Hg. An Au coating proved successful, trapping the Hg as a gold amalgam, thus reducing its volatility. Parameters optimized were fuel flow, percentage obscuration of the light beam and tube height above the burner slot. It was found that low fuel flow, high percentage obscuration and high tube height were important for maximum sensitivity. Sensitivity of the technique was 0.0598 mg l–1 for a 2 min collection and 0.0326 mg l–1 for a 5 min collection of analyte. Precision was good with an RSD of 2.9%. The effect of interferences were examined and the atom trap was used to determine Hg in sediment. The technique was useful for this type of sample as the Hg level was expected to be high in the sediment. A comparison of the atom trapping technique and the cold vapour method was carried out and the results were found to be in close agreement.