The determination of zinc in blood plasma by atomic absorption spectrometry

Abstract

Atomic absorption spectrometry has been used in the analysis of plasma zinc because of its sensitivity and simplicity. Dilution techniques reduce the viscosity of plasma and facilitate direct analysis, but viscosity differences can produce deviations in aspiration rates between sample and standard, and so cause errors. A direct (1 + 4) dilution of plasma with deionized water is suggested. Working zinc standards are prepared in 5% glycerol to approximate the viscosity characteristics and aspiration rates of the diluted plasma samples. The analytical curves for diluted plasma samples and 5% glycerol working standards proved identical. Plasma zinc concentrations are accurately calculated from a daily working curve. The accuracy of the method exceeds 99% and recovery of added inorganic zinc to a pooled plasma averages 99.8%. The precision is primarily limited by baseline drift. A confidence interval of ± 2 μg/100 ml was achieved by means of six contiguous 10s-integration readings. The method is free of nebulizer clogging and matrix interferences and is not subject to significant day-to-day variations. Because the method is accurate, sensitive, reliable and specific, it should be useful in the clinical laboratory.