Development of a Validated High‐Performance Liquid Chromatographic Method for Simultaneous Quantification of Critical Impurities in Trihexyphenidyl Hydrochloride

In this contribution, an efficient high-performance liquid chromatographic (HPLC) method was developed for the simultaneous determination of four impurities in trihexylphe idyl hydrochloride. The developed HPLC method was based on an octadecylsilane-bonded silica gel column (Agilent TC-C18 250 mm × 4.6 mm, 5 µm) as the stationary phase, and the solvents were sodium hexafluorophosphate 0.05 mol/L and methanol for the gradient elution at a flow rate of 1.0 mL/min, with the injection volume of 20 µL, the ultraviolet (UV) detection at a wavelength of 210 nm, and the column temperature of 30°C. Under the established chromatographic conditions, all four target impurities were completely eluted within 30 min. The proposed method demonstrates good specificity, precision, robustness, and accuracy for the quantification of the four critical impurities in trihexyphenidyl hydrochloride, and was successfully applied for the analysis of trihexyphenidyl hydrochloride in a pharmaceutical preparation.