Abstract
The novel, rapid high performance liquid chromatographic method for the determination of ketoprofen lysine salt was developed and validated. The method can simultaneously assay methyl‐p‐hydroxybenzoate, used as a preservative in OKI spray. The separation was carried out on a C18 μBondapack (300×3.9 mm i.d., 10 µm particle size) column using acetonitrile—0.05 M KH2PO4 buffer (60∶40, v/v) as mobile phase (pH value 3.0 was adjusted with orthophosphoric acid) at a flow rate 1.5 mL min−1, temperature of the column 20°C, and UV detection at 254 nm. The method was found to be linear (r>0.9999) in the range of 8–24 µg mL−1 for ketoprofen lysine salt, and 7.5–2.5 µg mL−1 (r>0.9998) for methyl‐p‐hydroxybenzoate. The developed method was successfully applied to the determination of ketoprofen lysine salt, its investigated preservative in commercial formulation. The recovery for ketoprofen lysine salt and methyl‐p‐hydroxybenzoate were 100.2% and 100.4 with RSD of 0.6 and 0.7%, respectively. The method is rapid and sensitive enough to be used for the analysis of OKI® spray.