Simultaneous determination of five nitroimidazole antimicrobials in pharmaceuticals using HPLC-ESM and QAMS methods

A green, rapid, and simple HPLC-External standard method (ESM) and a quantitative analysis of multi- components with a single-marker (QAMS) method were established for the simultaneous determination of five nitroimidazole antimicrobials (Metronidazole sodium chloride injection, Tinidazole injection, Ornidazole sodium chloride injection, Morinidazole sodium chloride injection, Secnidazole tablets) in pharmaceutical preparations. The five specified drugs were chromatographed via HPLC on a ZORBAX SB-C₁₈ (150 mm×4.6 mm, 5 μm particle size) analytical column using a mobile phase consisting of methanol-0.1% v/v triethylamine (26:74 v/v, pH adjusted to 3.0 with phosphoric acid) with isocratic elution and monitored by photodiode array detector at 316 nm. The chromatographic separation was accomplished within a short run time (less than 20 min) for the studied analyte. Using metronidazole as internal reference, the relative correction factors of each constituent were calculated were established, and the contents of each component of 5 nitroimidazole were calculated to achieve QAMS. The measured results were verified by the ESM. The methods were validated in terms of linearity, intra- and inter-batch precision, accuracy, stability, and recovery. The proposed ESM and QAMS methods could simultaneously determination of the studied analyte, and they were successfully applied to the analysis of the above cited drugs in pharmaceutical preparations with excellent accuracy and precision. In addition, the analytical greenness (AGREE) and blue applicability grade index (BAGI) metric tools were used to evaluate the greenness and environmental friendliness of the developed methods. AGREE scores of QAMS and EMS were 0.66 and 0.59, and BAGI scored 82.5 and 77.5, respectively.