title: Colorimetric determination of poly(N-vinyl-2-pyrrolidone) in contact lens solutions.
abstract: A rapid colorimetric method is presented for the quantitative determination of poly(N-vinyl-2-pyrrolidone) in contact lens solutions. The method is simple, requires no sample pretreatment, and uses only a small volume of sample. The procedure is based on the measurement of the net absorbance of a poly(N-vinyl-2-pyrrolidone)- Congo red complex at 545 nm. An accuracy of greater than +/- 4% was obtained for the concetnration ranges usually found in contact lens solutions with a minimum detection level of 10 ppm. The method is useful as a screening procedure for solutions of unknown composition and as a quality assurance procedure for routine determinations.
mesh_terms: D003124:Colorimetry; D003261:Contact Lenses; D009883:Ophthalmic Solutions / Q000032:analysis; D011205:Povidone / Q000032:analysis*
chemical_list: D009883:Ophthalmic Solutions; D011205:Povidone