Determination of Mercury in Soils by Flameless Atomic Absorption Spectrometry

Abstract

Mercury analyses of acceptable accuracy for geochemical prospecting were obtained on ten New Zealand soil samples, containing 2 to 10% of total organic matter, using a simple single beam atomic absorption spectrometer combined with a cold gold filter that removed mercury from the vapors released on heating the sample. Positive errors due to absorption of the 253.7 nm spectral line by residual organic matter compensate, more or less, for the loss of mercury from the system as elemental mercury and as volatile mercury-organic compounds.A modification of the analytical procedure, using two gold filters heated to 170 degrees C during mercury collection, gave results lower than the values obtained by an acid oxidizing digestion of the samples with subsequent evolution of mercury from the solutions by reduction with stannous chloride. These low results suggest that as much as 30% of the mercury in the soils tested is present as volatile mercury-organic compounds.