Determination of Pyridine as a Decomposition Product in Ceftazidime and Mouthwash Solution

Abstract

In this study, a dynamic headspace liquid-phase microextraction method is reported for the extraction and preconcentration of pyridine as a decomposition product in some pharmaceuticals before its determination by gas chromatography–flame ionization detection. In the practical procedure, 5 µL of dimethyl sulfoxide (extraction/collection solvent) containing 1-pentanol (internal standard) is placed into a liner-shaped extraction vessel. The vessel is passed through the septum of a vial containing the sample solution. Then it is placed into a water bath thermostated at 70 °C. After a predetermined time, 1 µL of the extraction/collection solvent is removed and injected into the separation system. The factors influencing the extraction efficiency including extraction/collection solvent kind and its volume, ionic strength, extraction time, extraction temperature, and pH were investigated and optimized. Under optimum extraction conditions, the method showed a wide linear range between 0.012 and 500 mg L−1. Enrichment factor and extraction recovery were obtained as 314 and 94%, respectively. Limit of detection was calculated as 0.004 mg L−1 in solution and 0.08 mg kg−1 in solid. Relative standard deviation for the extraction of 0.05 mg L−1 of the analyte was obtained as 4 and 6% for intra-day (n = 6) and inter–day (n = 4) precisions, respectively. Finally, the target analyte was determined in ceftazidime and mouthwash solution by the proposed method.