Mh. Arbab-zavar et M. Hashemi, Evaluation of electrochemical hydride generation for spectrophotometric determination of As(III) by silver diethyldithiocarbamate, TALANTA, 52(6), 2000, pp. 1007-1014
A batch electrochemical hydride generation system was developed for the spe
ctrophotometric determination of inorganic As(III) by silver diethyldithioc
arbamate. This method is based on electrochemical reduction of As to Arsine
(AsH3) in acidic media and on the subsequent reaction of AsH3 with silver
diethyldithiocarbamate to give an absorbing complex at 525 nm. The electroc
hemical generator consisted of a cathode cell separated from the anode cell
by a porous glass frit and was operated with a constant direct current. A
pre-activated graphite rod was used as cathode material for the production
of AsH3. The parameters related to the electrochemical hydride generation w
ere investigated. Under optimized conditions, only As(III) can be converted
to AsH3 and a pre-reducing stage is required for total inorganic As analys
is. The characteristic data of the electrochemical hydride generation and c
ommon hydride generation by NaBH4 were compared. Also, the effects of inter
ferences and their elimination were investigated. An absolute detection lim
it of 0.5 mug (3s(b)) and a concentration detection limit of 0.05 mug/ml we
re obtained using a 10 ml sample volume. The relative standard deviation fo
r five replicate analysis of 30 mug As(III) was 1.2%. The accuracy and reco
very of the method were demonstrated by analysing spiked artificial sea wat
er and tap water. (C) 2000 Elsevier Science B.V. All rights reserved.