Polarographic determination of zinc in eye drops and validation of the method.

Differential pulse polarography was used to study the electrode behavior of zinc (II) in various stock solutions. In view of the surfactants like methylcellulose derivatives present in the pharmaceutical preparations examined, which affected the course of the polarograms recorded, 0.5 mol l-1 ammonium buffer, pH 10.0, was found to be an optimum solution for the study. In a strong alkaline solution, zine currents were no longer suppressed by the methylcellulose derivatives. To compare the polarographic data obtained for "Cincol", "Oculosan" and "Visine Sensitive" eye drops, zinc (II) was determined in those eye drops by atomic absorption spectrometry without mineralization. Statistical evaluation of the data showed the DPP procedure developed to be characterized by satisfactory accuracy and precision (RSD : 0.93% ("Cincol"), 0.82% ("Oculosan"), 0.82%; ("Visine Sensitive")).