A new micromethod for colorimetric determination of zinc in serum

A simple micromethod with a colorimetric reagent of high sensitivity was developed for the determination of zinc in serum. For the color reagent 2-(2-pyridylazo)-5-dimethylaminophenol (PADAP) was used. Coefficients of variation of the within-day precision were 6.65 and 2.24% for zinc standard at concentrations of 0.1 and 0.5 microgram/ml, respectively. The mean recovery by this method was 101.2% (S.D.: 3.56%). Zinc concentrations measured by the above method showed good agreement with those by atomic absorption spectrophotometry, with a correlation coefficient of 0.934. Serum zinc values of 50 healthy adults (38 females, 12 males) ranged from 63 to 116 microgram/100 ml (mean: 89.68 microgram/100 ml, Sd.: 13.28 microgram/100 ml).