sample preparation

Using reagents and instruments:

1. A balance with a sensitivity of 0.01g

2. Glassware: conical flask, beaker, separating funnel, measuring cylinder, stoppered test tube, dropper, pipette, etc

3. Small crusher or bowl grinder

4. Filter paper, absorbent paper, etc

a、 Corn, rice, wheat, dried potatoes, beans, peanuts, walnuts (flour, peanut butter do not need to be crushed)

Take 5g or more of the sample and crush it. Accurately weigh 2.0g of the sieved sample and place it in a conical flask with a stopper. Then add 10.0ml of methanol aqueous solution (55:45) accurately (for peanuts and walnuts, 8ml of petroleum ether or n-hexane needs to be added and shaken, let it stand and separate into layers, and release the lower layer into a beaker). Cover the flask tightly, seal it with water, shake it on an shaker for 30 minutes (700r/min), filter it dry with qualitative fast filter paper, dry the filtrate as much as possible with a cold air blower, and dissolve it in 0.2ml of water to obtain the sample extract. According to the national allowable quantity standard of the sample, dilute the extract with diluent (see Table 1: Sample Dilution Table).

b、 Soy sauce, vinegar, fermented wine

Weigh 25.0g of the sample into a small beaker, transfer the sample to a separating funnel with 5ml of distilled water, add 20ml of chloroform, add a stopper, gently shake for 3 minutes, and let it stand for layering. Release the lower layer of trichloromethane and filter it through an anhydrous Na2SO4 filter pre wetted with approximately 5g of aminochloromethane in an evaporating dish. Add 5ml of trichloromethane to a separating funnel and repeat shaking extraction. Filter the trichloromethane layer into the evaporating dish and wash the filter with a small amount of trichloromethane. The washing solution is then placed in the evaporating dish and dried with a cold air blower. After drying and cooling, add 2.5ml of water accurately to fully dissolve the condensed matter in the evaporating dish. According to the national allowable quantity standard of the sample, dilute the extract with diluent (see table below).

Sample dilution table:

Operation steps

1. Read the user manual thoroughly before conducting the test, and return the test strip card and the sample to room temperature before use.

2. Take out the test strip card from the original packaging bag, open it and place it flat on the table. Please use it as soon as possible within 1 hour.

3. Use a dropper to aspirate the sample solution to be tested, drop 3 drops into the sample well, and start timing after adding the sample.

4. The result should be read within 8 minutes, and reading after 12 minutes is invalid.

Result judgment

Positive: When position C shows a red line but position T does not show color, or when position C shows a red line but position T shows a significantly lighter color than C, it is considered positive. The positive result indicates that the AFB1 content exceeds the allowable amount of the sample.

Negative: When a red line appears at position C and a red line appears at position T, and the color of the T line is close to or darker than the C line, it is considered negative. The negative result indicates that the AFB1 content is lower than the allowable amount of the sample.

Invalid: When position C does not display a red line, regardless of whether position T displays a red line or not, the test strip card is invalid. Suggest using a new test strip card to retest according to the requirements of this manual.

important clause

1. Please follow the operating steps for testing, and do not touch the display area of the test paper during operation.

2. If expired, damaged, contaminated, or ineffective products are found during purchase, please replace them at the place of purchase.

3. This product should be stored in a dry and cool place (4-30oC), with a shelf life of 18 months. The production date can be found in the packaging.

4. This product is disposable and should not be reused. Do not use diluents that are not included with this product.

5. This reagent is a screening reagent, please use other methods to further confirm any positive results.