Viscosity adaption for an automated micromethod of flame atomic absorption spectrometry, and intracellular trace-element analysis after pressure decomposition: zinc determination in plasma and erythrocytes.

Abstract

Abstract We measured zinc in the plasma of 50 normal persons, and in erythrocytes of six, by an automated micromethod of atomic absorption spectrometry. Using a rotation viscometer, we measured the viscosity and flow behavior of plasma, undiluted and equi-volume diluted (with water), from 12 patients, and, for comparison, of two- to 20-fold dilutions of an 870 mL/L glycerol solution. Erythrocytes were washed three times, lyophilized, and wet-ashed in a pressure decomposition device. The mean viscosity of equi-volume diluted plasma is about the same as that of the glycerol solution diluted 7.5-fold. The observed concentration of zinc in normal plasma was 13.8 (SD 1.9) mumol/L, with intra-assay CV (n = 30) of 2%, day-to-day CV (n = 22) 3.8%, and accuracy (measurement of an aqueous std.) 2.5%. The mean normal value for erythrocyte zinc was 34.7 micrograms/g, with intra-assay CV (n = 8) 5%, day-to-day CV (n = 6) 5.9%, and accuracy 4.6%. Our results compare well with those by neutron activation analysis, the differences in values being 3% for plasma, 1% for erythrocytes.