Spectrophotometric determination of trace sulphate in rain and snow after preconcentration with 2-aminoperimidine on a membrane filter.
A simple and precise preconcentration technique, based on collecting a precipitate on a membrane filter and dissolving the filter and precipitate in an organic solvent, has been applied to the spectrophotometric determination of trace sulphate in rain and snow. The sulphate is precipitated with 2-aminoperimidine and the resulting compound is dissolved in nitric acid, made alkaline with sodium hydroxide and then adsorbed on tetradecyldimethylbenzylammonium nitrate. The precipitate is then collected on a membrane filter and both precipitate and filter are dissolved in dimethylsulphoxide (DMSO). The absorbance of the DMSO solution is measured at 550 nm against a reagent blank. The molar absorptivity is 2.1 x 10(4) 1 . mole(-1) . cm(-1) and the coefficient of variation for six measurements is < 1.5%. The detection limit (S/N = 3) is 0.06 mug of sulphate in 5 ml of sample solution.
Shida
J
J
Department of Applied Chemistry, Faculty of Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa-shi, 992 Japan.
Satake
H
H
Ono
N
N
Fujikura
T
T