New procedures of Metronidazole determination by the method of Gas-Liquid Chromatography

Abstract

Metronidazole is the most popular representative in the group of medicines of 5-nitroimidazole derivatives. Based on the information about metronidazole side effects and its interaction with alcohol it is a potential analyte in forensic toxicology. The purpose is to develop GLC-procedures of metronidazole quantification and carry out their step-by-step validation to choose the optimal variant for further application in analytical toxicology. The chromatographic conditions has been chosen for metronidazole determination by the method of gas-liquid chromatography in two variants of performance with flame-ionization and mass-spectrometry detection with temperature program changing during the analysis from 70°C to 250°C or 320°C respectively. The GLC/FID-analyses were performed using gas chromatograph HP 6890 Hewlett Packard; column – HP-1 Q0.32mm × 30 m, 0.25μm, 100% dimethylpolysiloxane. The GLC/MSD-analyses were performed using Agilent 6890N Gas Chromatograph; columns – 1) HP-5MS Q0.25mm × 30m, 0.25μm, 5% diphenylpolysiloxan/95% dimethylpolysiloxan; 2) DB-17MS Q0.25mm × 30m, 0.15μm, 50% diphenylpolysiloxan/50% dimethylpolysiloxan; columns are connected sequentially through Deans switch. Under proposed conditions metronidazole and four other 5-nitroimidazole derivatives (tinidazole, ornidazole, secnidazole, nimorazole) are separated and detected without preliminary derivatization. In the method of GLC/FID the retention time for metronidazole is 9.08 min, in the method of GLC/MSD – 12.01 min. New GLC-procedures of metronidazole quantitative determination under proposed conditions have been developed. Their validation by such parameters as stability, linearity, accuracy and precision in the variants of the method of calibration curve, method of standard and method of additions has been carried out and acceptability for application has been shown.