The Tekran 2537A mercury vapour analyser, designed to measure Hg in air by
cold vapour atomic fluorescence spectrometry, has been modified to determin
e Hg in solution. The new 'front-end', required to generate Hg degrees vapo
ur from acidified waters or acid leachates, is described. Using 1% NaBH4 as
reducing agent, a 12 mt water sample can be analysed, at a rate of 1 every
6 min, for Hg to a detection limit of 0.8 ppt (ng L-1). Instrumental preci
sion is typically 1% relative standard deviation (RSD) at levels of Hg from
10 to 200 ppt. Results for 10 analyses of the international water standard
, NIST 1642b, are 1530+/-20 ppt Hg, agreeing well with the certified value
of 1480+/-130 ppt. Nineteen geological standard reference materials (soils,
sediments and tills) were used to assess accuracy. Results for these sampl
es, digested in aqua regia in triplicate, showed good agreement with recomm
ended values for all but two, SO-3 and TILL-I. However, results by this met
hod for these two standards were confirmed by an independent method, direct
atomic absorption spectrometry. Average method precision was shown to be 5
% RSD over the range 10 ng g(-1) to 35 mu g g(-1) Hg.