A method has been developed for the determination of H2S and FeS in se
diments. FeS is converted into H2S which is flushed from the samples d
irectly into an excess of chlorine bleach, NaClO or KClO with some Zn2
+ added. Either the excess can be titrated back potentiometrically wit
h As2O3, or the sulphate formed can be measured colorimetrically. The
precision is primarily controlled by the homogeneity of the sediment s
uspensions and can be better than 99%.