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Pesticide residue analysis is an analytical technique for trace components in complex mixtures.
It requires high sensitivity, low detection limit, and high accuracy, as well as new equipment and detection techniques, as well as fine micro-manipulation methods
.
Due to the wide variety of pesticides and their different chemical structures, different pesticides require different detection methods
The pesticide residue detection process is sample preparation-extraction-purification-concentration-constant volume detection
.
1.
Sample preparation
Before sample analysis or sample storage, the collected samples are often reduced and pre-processed, and laboratory test samples and backups are prepared to meet the needs of further processing and analysis
.
Powder: sample by quarter method after mixing
.
Grain and grain: After grinding and mixing, proceed according to the quartering method
.
Small fruits and vegetables: Cut and mash before mixing
.
The most convenient method is to use a continuous masher or homogenizer to process the entire sample, such as using a juicer to break the tomatoes into juice
Large-volume fruits and vegetables: If the sample is particularly large (such as cabbage, etc.
), use manual chop
.
At this time, it should be noted that the pesticide residues are not evenly distributed in the sample, especially when the large sample is cut up to prepare the analysis sample, and more attention should be paid to the uneven distribution of the pesticide residue
Water and other liquid samples: mix well
.
Filter to remove floating matter, sediment and mud
The sampling location of the sample has a great influence on the results of pesticide residue analysis.
In international trade, for the same agricultural product, due to different sampling locations or processing methods, the pesticide residues will be caused when compared with the MRL (maximum allowable residue) Confusion, such as beans with pods and without pods, and whether apricots have pits or not, the calculated pesticide residues are quite different
.
Table 6-1 shows the collection locations and processing methods of some common agricultural product samples
Table 6-1 Collection location and treatment of samples for pesticide residue analysis in important grains, fruits and vegetables
Related links: Determination of pesticide residues and other harmful substances in food
