Application:
Lead in food is a toxic metal, mainly from contamination during food processing, packaging and storage. Excessive intake of lead can cause poisoning, which can lead to anemia, neurological dysfunction and kidney damage. The country has strict limits on lead content in food, especially baby food, and has established national standard methods for determining sulfur content, namely disulfide zone colorimetric method and atomic absorption method. However, the disulfide zone colorimetric method is complicated in operation and poor in selectivity. It also requires the use of highly toxic potassium cyanide reagents and organic solvents, which is unacceptable for analysts. Atomic absorption method samples are difficult to handle, high cost, and limited in instruments, so they are not suitable for rapid on-site testing. Therefore, we have developed a rapid detection box for heavy metal lead, suitable for rapid detection of preserved eggs, vegetables, fruits and other samples.
Application method and result judgment
1. Sample processing:
Sugar sample: Weigh a 2.5G sample, put it into the sample cup, add 10ml of distilled water or purified water, and then add 1 drop of indicator a, stir to dissolve and wait for measurement.
Vegetable and fruit samples: Take an appropriate amount of the sample, cut it with scissors, weigh 2.5G, put it into the sample cup, add 10ml of distilled water or purified water, add 1 drop of indicator a, soak for 10min, and wait for the test.
Preserved egg sample: Take an appropriate amount of shelled egg protein, cut it off with scissors, weigh 2.5G, put it into a sampling cup, add 10ml of distilled water or purified water, then add 1 drop of indicator a, soak for 10 minutes, and wait test.
2. Detection
Take 1ml of the above solution and put it in a 1.5ml centrifuge tube. Add 3 drops of indicator B, 1 drop of indicator C and 1 drop of indicator D in sequence. Shake well and react for 3 minutes to observe the color change.
At the same time, use pure water or distilled water for blank control.
3. Results judgment
Compare the color development results of the sample and the blank control. If the color of the sample is obviously darker than the blank (orange-red to red), it indicates that the heavy metal lead content in the sample exceeds the national limit standard. If the color of the sample is the same or similar to the color of the control, it means that the heavy metal lead in the sample is not detected.
Detection limit
0.2 mg/kg
Precaution
1. The rapid test box is a rapid on-site detection method. It mainly detects the content of ionic lead in the sample. The total amount of ionic lead and organic lead in the actual sample may be higher than the test result. Positive samples should be sent to the laboratory for confirmation by standard methods.
2. During the detection process, when indicator B, indicator C and indicator D are added successively, each reagent should be shaken before adding the next one.
3. Test water requirements: Distilled or purified water is recommended for dilution, tap water or mineral water is not allowed.
4. The used centrifuge tube can be reused after cleaning.
5. If the indicator D is placed in the refrigerator, the shelf life can be extended to 1 year.
Storage conditions and shelf life
Put it in a ventilated and dry room temperature environment, the shelf life is 6 months.Food Test Kit suppliers
website:http://www.chinalabequipment.com/point-of-care-testing/food-test-kit/ |