Simple colorimetric method for seminal plasma zinc assay

Zinc concentration in seminal plasma is one of the best biochemical parameters with which to assess prostatic function in the study of male infertility. Nevertheless, this parameter is not determined in many laboratories because of technical difficulties. In this paper a simple colorimetric method for seminal plasma zinc assay is presented. This assay is performed with only one reagent solution making deproteinization and extraction with organic solvents unnecessary. The method is based on the reaction between 1-(2-pyridylazo)-2-naphthol and zinc which yields a coloured complex, that is soluble in the reagent solution when dodecyl hydrogen sulfate sodium salt is present. The solubilized complex has an absorbance peak at 560 nm. The accuracy of this method is proved by statistical comparison with atomic absorption spectrophotometry. Furthermore, the method has a good precision and is free of interference.