Evaluation of a commercially available kit for the colorimetric determination of zinc in human seminal plasma.

A kit from Wako Pure Chemical Industries for colorimetric determination of zinc has been evaluated for its possible use in the determination of zinc in human seminal plasma. The within-assay variation for 15 replicates of each of two seminal plasma samples having zinc concentrations (mM) of 0.43 +/- 0.025 and 6.06 +/- 0.125 (mean +/- SD) was 5.7% and 2.1%, respectively. The between-assay variation after analysis of 15 replicates of a seminal plasma sample (zinc conc. 5.6 mM) on different days was 2.3%. No interference from other metal ions present in seminal plasma was observed. The average % recovery of zinc added to seminal plasma was 102.7 +/- 1.77 (mean +/- SD). A close correlation (r = 0.996, n = 105) was found between the levels of zinc determined by the colorimetric method and that determined by atomic absorption spectrophotometry as reference method. It is concluded that the present colorimetric method, which is fast, sensitive and linear over the entire concentration range of zinc present in human seminal plasma, can be recommended for use in semen analysis laboratories.