Determination of heparin on intraocular lens surfaces by ion chromatography

A sensitive and selective method has been developed for the determination o f heparin on heparin coated PMMA, poly(methyl methacrylate), intraocular le nses. Heparin was hydrolysed to glucosamine and glucuronic acid, and the co ntent of glucosamine was determined using ion chromatography with pulsed am perometric detection. In order to verify that a complete hydrolysis was obt ained for the heparin on the coated intraocular lenses, electron spectrosco py for chemical analysis (ESCA) was used for analysing traces of sulphur on the lens surfaces. The sensitivity of the method allows quantitative deter mination of 150 ng of heparin on one individual lens. The new method was co mpared to a standard spectrophotometric method, measuring the colour intens ity of a heparin toluidine blue complex. Correlation between the methods wa s shown for samples prepared from PMMA lenses coated with different amounts of heparin. (C) 2001 Elsevier Science B.V. All rights reserved.