Quantitative HPTLC Determination of Elemental Sulfur in Sulfur Topical Medications

Abstract

A method was developed for determination of elemental sulfur in sulfur topical pharmaceutical preparations involving separation on a preadsorbent HPTLC silica gel plate with fluorescent phosphor, detection by fluorescence quenching, and quantification by densitometric scanning. Sulfur was directly detected and quantified on the plate at levels as low as 800 ng, and no interference was encountered from other ingredients in the medication formulations. The method was applied to the analysis of commercial liquid and cream preparations having respective label values of 5% and 8% sulfur, and recoveries averaged 99.3 and 99.5%. An unknown cream medication was assayed using the method and the accuracy of the result was validated by standard addition. All analyses were carried out with 5 or 6 replicates to evaluate precision, and coefficients of variation ranged from 2–4%.