Application of iron(III)-hydroxamic acid complexes in the spectrophotometric determination of poly(vinyl alcohol) in pharmaceutical preparations

Abstract

A spectrophotometric method is presented for the quantitative determination of poly(vinyl alcohol)(PVA) in contact lens solutions and eye-drops. The method is simple and requires no sample pre-treatment. The procedure is based on the measurement of the absorbance after iron(III)-hydroxamic acid reaction with PVA. The method is useful in quality control and as a screening procedure for solutions considered as PVA-containing mixtures of an unknown type. As the absorbance is dependent of the content of residual acetate groups in the PVA, the type and ester value can be determined.