BIOSAMPLING FOR METAL SPECIATION .1. DETERMINATION OF CHROMATE IN THE PRESENCE OF CR(III) BY SEPARATION WITH CELL-MEMBRANES AND GFAAS

Human erythrocytes (ery's) under physiological conditions are capable of a selective uptake of dissolved chromates beside Cr(III) from aqueous solutions. For sampling the mechanical stability of the red blood cells is increased by immobilization in Ca-alginate beads without loss of the biochemical activity against Cr(VI). Radiotracer studies were performed in order to determine the influence of temperature, pH, and concentration and solubility of chromates on the accumulation, which follows a Michaelis-Menten kinetics. After sampling the ery's are separated from the gel and introduced into a multiple-step clean-up procedure preceding a GFAAS measurement of chromium. The direct determination of chromium in erythrocytes (and comparable matrices) by GFAAS is supported by the use of oxygen as alternate gas during the thermal decomposition of the samples, leading to advantages in routine analysis. The statistical parameters of this method are critically reviewed. The combination of biosampling and GFAAS represents a new way for metal speciation, especially in cases where decomposition of the analyte during standard sampling procedures is likely; this is demonstrated for Cr(III)/Cr(VI) as an example in view of immission measurements of Cr(VI) in airborne particulates. © 1990 Springer-Verlag.