Development and Validation of EG, DEG and Menthol Cough Syrup Determination by Gas Chromatography

Ethylene Glycol (EG) and diethylene Glycol (DEG) are two contaminants which cause numerous human health problems. Traditionally, methods for determining EG, DEG, and menthol content have been developed separately. There is a need for a reliable method to simultaneously quantify these compounds, particularly in pharmaceutical formulations like cough syrups. This study aims to develop and validate a gas chromatography (GC) method for the simultaneous determination of EG, DEG, and menthol content, ensuring accuracy and precision in pharmaceutical analysis. A gas chromatography method was developed using a DB-624 column (30 m x 0.53 mm x 3.0 µm), with 6% cyanopropyl/phenyl, 94% polydimethylsiloxane) and nitrogen as the carrier gas. Detection was performed using Flame Ionization Detection (FID). 2,2,2-Trichloroethanol was employed as the internal standard, and methanol was used as the diluent for sample preparation. The method was validated according to ICH and IP guidelines, focusing on parameters such as linearity, precision, robustness, solution stability and system suitability. The method demonstrated excellent recovery rates for EG, DEG, and menthol, ranging from 100% to 101%, 99% to 101%, and 99% to 101%, respectively. Linearity was established between 50 ppm to 150 ppm, with correlation coefficients of 1.0 for EG, 0.999 for DEG, and 1.0 for menthol. Precision, evaluated through repeatability and intermediate precision, showed RSD values below 2.0%. All parameters for robustness, system suitability, and solution stability were within acceptable limits.The developed gas chromatography method is reliable, efficient, and precise for the simultaneous determination of EG, DEG, and menthol in pharmaceutical products. The method's validation according to ICH and IP guidelines confirms its suitability for routine quality control in the pharmaceutical industry.