The original meaning of heavy metals refers to metals with a density greater than 4.5g/cm3, including gold, silver, copper, iron, mercury, lead, cadmium, etc. Heavy metals accumulate to a certain extent in the human body, which can cause chronic poisoning. But when it comes to environmental pollution, heavy metals mainly refer to biologically toxic heavy elements such as mercury (mercury), cadmium, lead, chromium, and metal like arsenic.
Heavy metals are very difficult to biodegrade, but on the contrary, they can accumulate thousands or hundreds of times under the biological amplification of the food chain, and finally enter the human body. Heavy metals can strongly interact with proteins and enzymes in the human body, causing them to lose their activity. They may also accumulate in certain organs of the body, causing chronic poisoning.
Due to the non degradability of heavy metals in the human body, various industries attach great importance to heavy metal detection. Therefore, we hereby introduce the pre-treatment precautions for heavy metal detection in food:
Note: This method mainly explains the first method for the determination of multiple elements in food according to GB 5009.268-2016.
matters needing attention
1. All pre-treatment tests, except for sample weighing, must be carried out in a fume hood. All cleaning must be done in advance with protective measures in place, and it is best to wear gloves and masks completely.
2. The digestive tract should be rinsed with clean water and rinsed three times with first grade water.
3. The digestive tract cannot be brushed with a brush.
4. Before using the digestive tube, it needs to be dried on an acid extractor or the residual water on the inner wall of the tube should be thrown out, and the outer wall of the digestive tube should be wiped dry with paper before use; Attention: The outer wall needs to be wiped dry with paper as much as possible, and the inner wall should be shaken as much as possible without any water droplets flowing out, otherwise it will have a certain impact on the results.
5. Gloves are required for weighing samples.
6. The sample should be placed at least one-third of the distance from the bottom of the sample digestion tube and two-thirds of the distance from the top of the digestion tube, otherwise it may adhere to the wall and wash unevenly.
7. It is best to weigh powder samples directly using weighing paper to generate static electricity.
8. After weighing, adding reagents to the digestive tract requires wearing a double-layer book cover to prevent the reagent from corroding your hands.
9. If there is nitric acid in the reagent, it needs to be of superior purity or higher purity.
10. When rinsing the sample digestion tube with reagents, the pipette tip should not be directly inserted into the inner wall of the digestion tube to avoid scratching the inner wall and damaging the digestion tube, which may affect the detection results.
Before adding reagents, it is best not to directly aspirate them from the original reagent bottle. It is best to pour them into a non contaminated reagent bottle and use them as needed.
12. After adding the reagent, shake well and let it stand for about 5 minutes.
13. After adding the inner and outer covers, let it sit and react for about 10-15 minutes
14. The microwave digestion device needs regular maintenance to maintain its internal dryness and cleanliness.
After digestion is completed, the transferred sample should be in a transparent state, otherwise it is considered incomplete digestion.
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