Commercially formulated anti-dandruff shampoos contain zinc pyrithione (ZPT)
as an active ingredient that has antifungal, antibacterial and
anti-seborrheic properties. The determination of ZPT concentration in
commercial anti-dandruff shampoos by differential pulse polarography (DPP)
was based on the electrochemical reduction of zinc ions in ammoniacal buffer
pH 10.2, and the linear dependence of the reduction differential pulse peak
current at the potential -1.33 V vs. concentration of zinc. Using the
calibration curve method, it was found that the range of linearity for the
determination of zinc concentration was from 1.28 x 10?5 to 1.39 x 10-4 mol
L-1 (linear regression equation: I = - 0.097 + 6.635 x 105c). Surface active
ingredients and micro-components in the shampoos did not exert a
polarographic interference for the determination of zinc and did not affect
the indirect determination of the content of the active ingredient ZPT. The
concentrations of zinc in the analyzed anti-dandruff shampoo samples were
determined by the standard addition method, resulting in 4.20 x 10-2 mol L-1,
1.76 x 10-1 mol L-1 and 1.82 x 10-1 mol L-1. The results of DPP
determinations of zinc and ZPT show that the content of ZPT was 0.28%, 1.15%
i.e. 1.19% and was below the maximum recommended level of ZPT in
anti-dandruff shampoos. This simple and sensitive differential pulse
polarography method is suitable for a routine and rapid control of the active
ingredient content, as well as for the quality control of anti-dandruff
shampoos.
Application of Net Analyte Signal Standard Addition Method (NASSAM) for Simultaneous Determination of Lead and Tin by Differential Pulse Polarography
