Water analysis
Filtrated and acidified water samples were analysed
(500 ml) without any further sample pre-treatment. The
method applied for the determination of dissolved
butyltins is hydride generation, cryogenic trapping, gas
chromatography and final detection by quartz furnace
atomic absorption spectrometry, as described earlier
(Ritsema, 1992, 1994). The standard addition technique
was used to quantify levels of butyltins. An internal
standard procedure (dimethylbutyltin bromide) was
used to check the derivatisation, purging and atomisation
efficiency; the recovery of the internal standard was
> 90% in these water samples. During inter-comparison
exercises, co-ordinated by the Community Bureau
of Reference (BCR), our laboratory achieved acceptable
results (within 20% of the mean value) in analysing
synthetic water samples. The limit of quantitation
(expressed as three times the standard deviation of a
real seawater sample low in butyltin) is 1 ng butyltin
cation litre -1 while the relative standard deviation
was better than 6% at 100ng butyltin cation litre -~
level.