Determination of toluene residues in diclofenac sodium raw materials by gas chromatography - Master's thesis - Dissertation

A gas chromatographic method was developed and validated for the determination of residual toluene in diclofenac sodium raw materials. The analysis was carried out using an HP-5 capillary column (0.53 mm × 30 m, 2.65 μm) with nitrogen as the carrier gas and a flame ionization detector (FID). The method employed isothermal conditions with a column temperature of 50°C, an injection port temperature of 200°C, and a detector temperature of 250°C. A direct split injection was performed, with dimethyl sulfoxide (DMSO) used as the solvent and isooctane as the internal standard. The internal standard method was applied to quantify the residual toluene content. The method demonstrated good linearity over the concentration range of 9.27–111.19 μg·ml⁻¹ (r = 0.9994). The average recovery was 97.27% (RSD = 2.80%, n = 9), indicating high accuracy and precision. The detection limit (LOD) and quantification limit (LOQ) were determined to be 0.59 μg·ml⁻¹ and 1.46 μg·ml⁻¹, respectively, which are sufficiently low for reliable residue analysis. Analysis of three batches of diclofenac sodium showed that toluene levels were within acceptable limits. In conclusion, this method is accurate, reproducible, and suitable for routine quality control of diclofenac sodium raw materials. It provides a robust and efficient approach for monitoring residual solvents, ensuring compliance with pharmaceutical standards and safety requirements.

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