Method for determining residual quantity of myclobutanil by SPE-GC/ECD (Solid Phase Extraction-Gas Chromatography-Electron Capture Detector)

Abstract

The invention provides a method for determining residual quantity of myclobutanil by SPE-GC / ECD (Solid Phase Extraction-Gas Chromatography-Electron Capture Detector). The method comprises the following steps of: (1) preparation of a standard liquid: weighing a myclobutanil standard substance and dissolving by an organic solvent to set volume so as to prepare a standard storage liquid; stepwise diluting the myclobutanil standard storage liquid to prepare standard working liquid with series of concentrations; (2) extracting residue in a sample; (3) purification: dissolving by an acetone-normal hexane mixed liquid, then, transferring to a Florisil solid phase column pre-sprayed by the acetone-normal hexane mixed liquid and spraying by the acetone-normal hexane mixed liquid; (4) detecting the residual quantity of myclobutanil in the sample by gas chromatography; (5) establishing a standard curve; and (6) calculating the residual quantity of myclobutanil. The detection method provided by the invention has the characteristics of simpleness and rapidness, and accuracy and reliability, and is of significant value to control the residual quantity of myclobutanil in tobacco for guiding safe and reasonable use of myclobutanil in tobacco.

Description

technical field [0001] The invention belongs to the technical field of trace analysis, and in particular relates to a method for measuring the residual amount of myclobutanil in tobacco by using SPE-GC / ECD. Background technique [0002] Myclobutanil is a triazole fungicide, which can inhibit the biosynthesis of pathogenic bacteria epikeratosterol. It has strong systemic property, high drug efficacy, safety to crops and long-lasting effect. It is mainly used to prevent and control various diseases caused by pathogenic bacteria such as ascomycetes and basidiomycetes. It has good control effects on powdery mildew, rust, scab, gray spot and brown spot, and is a promising fungicide . In recent years, with the extensive application of myclobutanil at home and abroad, its residue problems in the environment and agricultural products have become increasingly prominent, and have attracted great attention. [0003] At present, there have been relevant reports on the residue analysis...

AI Technical Summary

Problems solved by technology

The detection practice found that although this residue analysis method has high extraction efficiency, it has the following disadvantages: 1) Since acetone and methanol are used as extraction agents, impurities such as sugars, fats, and proteins are also easily extracted. There is a large interference in the detection. Although dichloromethane is used for multiple extractions, the operation steps are increased, which not only increases the workload, but also easily causes errors.

2) It is difficult to separate the extractant and the water phase, making the extraction and purification process relatively cumbersome

3) The method of column chromatography is not only complicated to operate, but also has poor reproducibility. It is not suitable for tobacco samples containing a lot of pigments, oils, and impurities. Improper purification, impurity peaks can easily interfere with the detection results

[0004] However, if the current detection method is used to detect the residual amount of myclobutanil in tobacco leaves, the defect is that there are many interferences, especially impurities such as nicotine and proteins are likely to interfere with the detection of myclobutanil residues.

Although the above method is easy to operate, it cannot effectively remove impurities such as nicotine and protein in tobacco leaves.

During the detection, the existence of nicotine and protein is easy to form interference peaks, which affects the detection accuracy of the target

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