Determination of docusate sodium by ion-pair high-performance liquid chromatography

To reduce the dependency on high-carbon-load chromatographic columns,a new method has been established for the determination of the content of docusate sodium using ion-pair high-performance liquid chromatography (IP-HPLC). Tetrapropylammonium chloride was used as the ion-pair reagent with a mobile phase, composition of acetonitrile:10 mmol/L tetrapropylammonium chloride solution = 66∶34, adjusting pH to 6.5 with 0.1% phosphoric acid solution,flow rate of 1.5 mL/min, detection wavelength of 214 nm,column temperature of 35 °C, and an injection volume of 25 μL,and quantified by an external standard method. The main peak of docusate sodium exhibited a tailing factor of 1.34. The method showed good linearity within the range of 0.02 mg/mL to 0.40 mg/mL, with a correlation coefficient (r) of 0.999 9. It also demonstrated good repeatability, with recovery ranging from 97.0% to 98.2% (n=6). The quantification limit was 3.31 μg/mL, and the detection limit was 2.76 μg/mL.In summary,the new method shows good durability, a wide linear range, and high sensitivity, it is suitable for the determination of docusate sodium.