Rapid-flow analysis using differential pulse polarography with automatic sampling.
Differential pulse polarography is used in a rapid-flow analysis system for automated determination of lead, zinc and ascorbic acid in acetate-buffered sample solutions, without the need for sample deaeration. By use of a nitrogen-segmented buffer stream at high flow-rates, high-speed sampling at up to 180 samples/hr can be obtained at a flow-rate of 22.8 ml/min through a polarographic flow-cell fitted to the dropping mercury electrode. A linear calibration range of approx. 0.1 x 10(-4)-1.0 x 10(-3)M is found for lead, zinc and ascorbic acid, with respective detection limits of 4.0, 0.8 and 0.2 x 10(-6)M, limited by the high base-line current and high noise-level. Vitamin C tablets can be routinely analysed without prior separation steps, provided the sample and wash solutions are matched in electrolyte composition. A precision of better than 1% RSD is obtained at a sampling rate of 120/hr.
Alexander
P W
PW
Department of Analytical Chemistry, University of New South Wales, P.O. Box 1 Kensington, N.S.W., 2033, Australia.
Marpaung
H
H