M. Thakur et Mk. Deb, Spectrophotometric determination of lead with N-hydroxy-N,N '-diphenylbenzamidine and diphenylcarbazone in airborne dust particulates and soil, ANALYST, 124(9), 1999, pp. 1331-1335
A simple, selective and sensitive method for the spectrophotometric determi
nation of lead in airborne dust particulate and soil samples is described.
The method is based on the selective extraction of lead at pH 10.0 +/- 0.2
with N-hydroxy-N,N'-diphenylbenzamidine (HDPBA). The yellow Pb-II-HDPBA com
plex shows maximum absorbance at 410 nm with a molar absorptivity of 1.6 x
10(4) l mol(-1) cm(-1). The sensitivity of the method is further increased
by the addition of a methanolic solution of diphenylcarbazone (DPCZO) to th
e extract. The pink Pb-II-HDPBA/DPCZO complex has a molar absorptivity of 7
.2 x 10(4) l mol(-1) cm(-1) at lambda(max) = 525 nm. The detection limit of
the method is 4 ng ml(-1) in the organic phase and the Sandell's sensitivi
ty of the method is 0.0015 mu g cm(-2). The relative standard deviation for
10 replicate measurements of Pb at a level of 1.0 mu g ml(-1) is 1.5%. The
method has been successfully applied to the determination of Pb-II in airb
orne dust particulates and soil samples.