An article on understanding heavy metal inspection work

Due to the fact that heavy metal content in food belongs to the trace range in heavy metal testing, there may be more external pollution and matrix interference during pre-treatment and measurement processes, which often leads to significant deviation in detection results. Sample pre-treatment is the most crucial step in food inspection. The suitability of pre-treatment methods directly affects the precision and accuracy of analysis results. Therefore, unifying pre-treatment methods is an important step to ensure inspection quality and improve inspection efficiency, which is conducive to eliminating interference from other components to be tested and shortening the pre-treatment time of samples. At the same time, the components to be tested can also be transformed into the state required for analysis and determination, so that the quantity and form of the components to be tested can adapt to the requirements of the selected analysis method, so as to ensure the smooth progress of the determination and the accuracy and reliability of the analysis and determination results, ensuring the accuracy and effectiveness of the detection data.

test method

The inspection of lead and cadmium shall be carried out in accordance with the determination methods of lead and cadmium in food in GB 5009.12-2017 and GB 5009.15-2014.

Sample collection

The reliability of monitoring data is not only affected by the detection method, but also directly related to the representativeness, quantity, collection method, and analysis location of the samples. For many samples, the impact of collection errors on the results is often greater than analysis errors. Sometimes, even correctly collected samples can seriously affect the accuracy of the data if not selected properly and stored properly. Therefore, in sampling, it is necessary to indicate the sampling date, batch number (packaged food), and quantity collected, which should reflect the hygiene quality of the food and meet the requirements of the inspection items for sample size.

(1) Vegetables, fruits, etc. should be fresh and ready to market, cleaned and dried, and the edible parts should be cut into small pieces and homogenized. Liquids (such as milk, fruit juice, etc.) should be thoroughly mixed before sampling.

(2) Grain and solid food should be sampled from different parts of each batch of food, including the upper, middle, and lower parts. After mixing, samples should be taken diagonally using the quartering method, and then mixed. Finally, representative samples should be taken.

(3) Meat, aquatic products, and other food products should be sampled separately or mixed according to the requirements of the analysis project.

(4) Bottled food or other small packaged food should be randomly sampled based on the batch number. For samples taken from the same batch number, there should be no less than 6 packages with a quantity of 250g or more, and no less than 10 packages with a quantity of 250g or less.

Preparation for experimental work

Sample pre-treatment is a crucial detection step after sampling and sample preparation. Without appropriate pre-treatment methods, even with representative samples and sensitive and reliable analysis and measurement methods, accurate and reliable analysis and measurement results may not be obtained due to incomplete extraction of the tested components or interference from other components, and even analysis and measurement cannot be carried out.