Pretreatment method for finished tea sample for dicofol pesticide residue detection

Abstract

The invention discloses a pretreatment method for a finished tea sample for dicofol pesticide residue detection. The pretreatment method comprises the following steps: adding water to moisten a crushed and dried finished tea sample, further adding a dicofol molecularly imprinted polymer, grinding, uniformly mixing, adding into a chromatographic column which is prefilled with the dicofol molecularly imprinted polymer, washing with deionized water, further eluting by using a mixed solvent composed of acetonitrile and glacial acetic acid and taken as an eluent, collecting the eluting liquid, concentrating and drying the eluting liquid, and dissolving and making the volume constant by using n-hexane. By adopting the pretreatment method, a simple grinding technique can be adopted, residual pesticides in the tea sample can be sufficiently adsorbed and extracted while cells of the tea sample are crushed, a great amount or harmful organic solvents are not used, and the analysis and detection cost can be greatly reduced; meanwhile as the dicofol molecularly imprinted polymer is taken as the adsorbent, the pretreatment method has the characteristics of high extraction efficiency on dicofol, good separation effect, small interference, small loss, accurate result and good recyclability.

Description

technical field [0001] The present invention relates to the field of pesticide residue detection, in particular to a sample pretreatment method before the detection of pesticide residues in finished tea leaves, and in particular to a fast, efficient, economical and environmentally friendly sample pretreatment method, which can be applied to various types of finished tea leaves Analysis of dicofol pesticide residues. Background technique [0002] At present, 18 countries and organizations in the world have issued 349 allowable pesticide residue standards for the amount of pesticide residues in tea, and some major tea importing countries have also formulated stricter regulations on the amount of pesticide residues in tea, making my country Tea exports are under enormous pressure. While intensifying inspections on my country's tea imports, more stringent pesticide residue limits (MRLs) have been formulated every year, tea inspection items have been expanded, and technical regul...

AI Technical Summary

Problems solved by technology

[0006] 1. Complicated and time-consuming

The entire sample pretreatment steps include 2-3 times of solvent extraction, concentrated sample loading, purification and elution, concentration, constant volume, and detection. From the beginning of sample crushing to the end of instrument detection, the entire process takes more than 4 hours. , the steps are cumbersome, the workload is heavy, and accurate results cannot be given quickly

[0007] 2. High cost

Many of these technologies require special equipment and consumables. For example, SPE technology requires special SPE cartridges. The current market price ranges from a dozen to tens of yuan each (the type and quality of the filler determine the price), such as GB / T 23204- The Cleanert TPT used in the 2008 national standard method is generally priced at about 100 yuan / piece; and this SPE cartridge is a disposable consumable and cannot be reused; in addition, the supporting solid-phase extraction device and booster pump are required for charging. Pressure-controlled speed, generally the lowest price is more than 3,000 yuan / set, so the actual consumption cost of a sample is more than 100 yuan

[0008] 3. Toxic and harmful organic solvents are consumed more (80-120ml) in the pretreatment process, causing environmental pollution and threatening the health of personnel