Method used for detecting formic acid residue in imidazole vermifuges

Abstract

The invention relates to the technical field of formic acid solvent residue detection, in particular to a method used for detecting formic acid residue in imidazole vermifuges. The method comprises the following steps: by using a derivatization technology, the formic acid is dissolved in a methyl sulfoxide solvent and reacts with methanol under the catalysis of sulfuric acid to generate methyl formate, and then a headspace sampling method is adopted to measure the methyl formate, so as to measure the formic acid residue. The method has the benefits that by selecting methyl sulfoxide as the solvent for detecting the formic acid residue, the problem that imidazole vermifuges can not dissolve in common solvents such as alcohol, ketone and esters solvent is solved; the derivatization reagent is improved; by replacing ethanol with the methanol, the esterification activity is relatively high, the derivatization reaction conversion rate is improved, and finally, the detection accuracy for the formic acid residue is improved; the concentration of the formic acid residue within detection range is good in linear relationship by adopting a headspace gas-chromatography method. Therefore, the method has the advantages that the operation is simple and convenient, the separation degree is good, the sensitivity is high, the repeatability is good, the data is accurate and reliable, and the like.

Description

technical field [0001] The invention relates to the technical field of formic acid solvent residue detection, in particular to a method for detecting formic acid residue in imidazole anthelmintics. Background technique [0002] Formic acid is often used in the refining process of imidazole anthelmintics (including albendazole, mebendazole, flubendazole, fenbendazole, oxfendazole, propoxyimidazole, lubendazole, and thiabendazole) As a solvent, ICH stipulates that formic acid is a third-class solvent with a limit of 0.5%, in order to strictly control its residual amount. In addition, formic acid residues will also affect the stability of Mbz, thereby affecting product quality and efficacy. [0003] Due to the active nature of formic acid, strong acidity, corrosiveness and reducibility, small molecular weight, low peak response, etc., it is difficult to directly measure it. At present, methods for the determination of formic acid include gas chromatography, liquid chromatogra...

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Problems solved by technology

[0004] Because ion chromatography requires specific instruments, and in liquid chromatography, formic acid peaks out quickly and will be interfered by solvent peaks. Because formic acid has a very low response in FID, it cannot meet the detection requirements. Although formic acid is converted by esterification Derived into ethyl formate for detection, which significantly improves the response in FID, but using ethanol as a solvent, the conversion rate of derivatization is not high, resulting in low accuracy of formic acid residual detection

The use of ECD detectors has not been improved. Although MS detectors can be used for detection, the experimental cost is relatively large

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