RESUMEN
OBJECTIVE:To establish a method for simultaneous determination of residual methylparaben,ethylparaben,nipa-sol and benzalkonium chloride in marketed eye drops. METHODS:HPLC method was adopted. The determination was performed on Hypersil GOLD C18 column with mobile phase consisted of 0.005 mol/L ammonium acetate(10 mL triehtylamine in 1 L solu-tion,pH adjusted to 5.0±0.5 with glacial acetic acid)-acetonitrile(45:55,V/V)at the flow rate of 1.0 mL/min. The detection wave-length was 262 nm(methylparaben,ethylparaben,nipasol)and 214 nm(benzalkonium chloride),respectively. The column tem-perature was 30 ℃ and sample size was 20 μL. RESULTS:The linear range were 1.2350-15.4380 μg/mL for methylparaben(r=0.9999),1.3170-16.3836 μ g/mL for ethylparaben (r=0.9997),1.2072-15.0894 μ g/mL for nipasol (r=0.9996) and 17.776-222.0 μg/mL for benzalkonium chloride(r=0.9999),respectively. Limits of quantitation were 2.0,2.0,2.0,1.11 μg,re-spectively;limits of determination were 0.375,0.375,0.375,0.333 μg,respectively. RSDs of precision,stability and reproducibili-ty tests were all lower than 2.0%. The average recoveries were 98.14%-102.48%(RSD=1.6%,n=9),98.79%-102.42%(RSD=1.3%,n=9),98.19%-102.49%(RSD=1.5%,n=9)and 98.76%-100.53%(RSD=0.6%,n=9),respectively. CONCLUSIONS:The method is accurate,reproducible,simple and suitable for the determination of residual methylparaben,ethylparaben,nipasol and benzalkonium chloride in marketed eye drops.