Application of the quadratic response surface in the polarographic determination of lead: biological samples.

Differential-pulse polarography was applied to lead determination in blood, urine and hair samples after pressurized acid digestion. Quantitative determination was carried out using a single analytical measurement of the experimental sample (without the need for addition or calibration methods), using the equation calculated as a result of the study of the quadratic response surface. The elimination of the possible interferences has been considered. The reliability of the analytical procedure was evaluated using relative standard deviations (2.34-11.93%) and recovery (97.28-103.92%) measurements.

Direct determination of zinc in insulin preparations by differential pulse polarography.

A rapid and direct differential pulse polarographic method for the determination of zine in insulin preparations is described. Optimum conditions were studied using 0.2 M acetate buffer (pH 4.1) as the supporting electrolyte. Agreement between the results by direct analysis and those by the procedure involving pressurized digestion was satisfactory.