A straightforward size exclusion chromatography (SEC) method was developed and validated for the determination of total polivinylpyrrolidone (PVP) in ophthalmic solutions using the unusual combination of size exclusion chromatography (SEC), ultraviolet-visible detection and quantitation of an analyte peak that elutes in the total exclusion volume of the column. Samples of opthalmic solutions are diluted with water and injected onto a TSKgel G1000PW, 7.5 mm i.d. × 30 cm, 12 μm column at 50°C, with 80:20 0.1M sodium acetate-methanol mobile phase and UV detection at 220 nm. Validation was successful for a stability indicating pharmaceutical method, with parameters including specificity, accuracy, linearity, and precision within typical pharmaceutical acceptance criteria. A stress study with acid, base, peroxide, heat, and light indicates that there is no interference from drug, product, or excipients.
A simple gradient reversed-phase high performance liquid chromatography (HPLC) method was developed for the simultaneous determination of total benzalkonium chloride (BAC) and pramoxine HCl in wound care solutions. Laboratory formulations were diluted 1 : 10 with water and injected into a HPLC system equipped with a Phenomenex, Luna CN column ( 100A, 5mm, 250 mm  4.6 mm) in order for BAC and pramoxine to separate from other excipients and be detected by a UV detector (l ¼ 262 nm). The mobile phase was 0.075 mM sodium acetate trihydrate buffer (pH ¼ 5.0) using multi-ramp gradient elution with acetonitrile. Quantitation was achieved by direct comparison of the peaks of BAC and pramoxine HCl of the sample to a reference standard of known concentrations. A stress study with acid, base, peroxide, heat, and light indicated no interference from drug product or excipients. The mean recovery results for both pramoxine and benzalkonium chloride at 100% level were 100.5 AE 0.3%, 100.5 AE 0.1% respectively (mean AE SD, n ¼ 6). In this report, the full experimental results from developing and validating this method are presented.
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