Rapid detection instrument should pay attention to fast and accurate

In times of frequent food safety, food testing equipment has a vast market demand. Accompanied by the increasing demand for food safety and other aspects of detection, due to the fact that there are many manufacturers of fast-track products, the accuracy rate of most regular fast-check products currently on the market is about 70%. Therefore, it sometimes causes food leakage. Sometimes it can cause misjudgment. Relevant experts propose to improve the production enterprises' access and product certification mechanisms to increase the threshold for the production and sales of fast-check products, ensure the sound development of the industry, and truly play the role of fast inspection as a primary guarantee for food safety.

Rapid detection instrument is favored
On June 1, the Food and Drug Administration of Shanxi Province deployed 132 sets of food safety and rapid inspection equipment to 11 cities and 121 food and drug administrations in the province. At the same time, training courses were held to strengthen the supervision of more than 200 grass-roots units in the province. Skills training for quick inspection knowledge and operation methods.

Recently, the Jiangsu Provincial Food and Drug Administration held the release ceremony of food safety rapid detectors for catering services throughout the province in Nanjing. Food and Drug Administrations in 13 provinces were equipped with detectors.

The food safety and rapid detection equipment for food and beverage services issued this time includes a set of food industry precision detectors and a set of synthetic dyes and industrial dye detectors. It is also equipped with a central thermometer and an ultraviolet illuminometer. This is the first time that the Food and Drug Administration of Jiangsu Province has issued food safety supervision and law enforcement equipment for catering services since fulfilling its food safety supervision function.

When the poor accuracy of test results must improve the access threshold <br> <br> food testing room interview, the reporter saw the staff are doing lentils pesticide residues by quick inspection instrument, the same one lentils, has twice come to do The results were very different. The first time the pesticide residue inhibition rate was 414, the second time the inhibition rate was 384, and the benchmark for testing was the critical index of 400. The manufacturers who provided us with food rapid testing products also emphasized that when the fast-checking results fluctuate, it is best to do three fast inspections and take the average value as a result. It is easy to have quality problems in foods such as fruits and vegetables, grain and oil, frozen goods and seasonings. For key varieties, we usually do several more tests. The head of the National Food Inspection Office said.

In this regard, Zhang Hongyan, deputy section chief of the Haidian district's urban and rural warehouse supermarket business division, has carried out self-inspection on supermarket foods. The accuracy rate of fast inspections needs to be improved urgently. Objectively speaking, the accuracy rate of most regular fast-track products on the market is currently about 70%. Because there are many manufacturers of fast-check products, the accuracy of fast-checking products varies from product to product. In the actual operation of the quick inspection product, there will be false positives, that is, the quick inspection has detected problems, but after further tests conducted by a state-qualified laboratory, there is no problem; there are also false negative cases, that is, there is no problem in quick inspection. However, after further tests conducted by nationally qualified laboratories have identified problems, these situations can sometimes cause food problems to escape the net and sometimes cause miscarriage of justice.

Prof. Luo Yunbo, a member of the Agriculture Products Risk Experts Committee of the Ministry of Agriculture, and Prof. Huang Kunlun, a deputy dean of the College of Food Science and Nutritional Engineering of the China Agricultural University and a doctoral tutor, told reporters that with the rapid development of the fast-checking market, good and bad products and exaggerated publicity have begun to appear. . The relevant state departments are brewing the mechanisms for access and product certification of manufacturers of fast-checking products to increase the threshold for the production and sales of fast-check products, ensure the sound development of the industry, and truly play the role of fast inspection as a primary guarantee for food safety. Experts revealed to reporters.

Rapid test equipment for effective evaluation

To evaluate the effectiveness of fast-checking instruments, the scientific, feasibility and applicability of fast-checking instruments should be evaluated theoretically: whether the principle of fast-checking instruments is correct and reasonable; whether quick-checking instruments are simple and easy to operate; The requirements on the operating environment and personnel, how anti-jamming capability and so on, these factors have a direct impact on the effectiveness of fast-checking instruments. Then some indicators of the rapid inspection instrument: accuracy, detection limit, precision, repeatability, reproducibility, anti-interference, and full analysis time were measured to evaluate the effectiveness of the rapid inspection instrument.

Accuracy: Indicates the degree to which the measured value corresponds to the true value. Since the fast-checking instrument is generally used for screening, it is generally not required to give accurate measurement values, as long as the content of the measured material exceeds the standard value (or limit value). If it is not exceeded, it is expressed as negative; if it is exceeded, it is expressed as positive. Therefore, when the accuracy (reliability) of the results is evaluated in a quick inspection apparatus, the false positive rate and the false negative rate are described.

The false negative in the quick inspection instrument means that the analyte content exceeds the standard value (or limit value), but the inspection result indicates that the analyte content does not exceed the standard value (or limit value), and the unqualified product is considered as a qualified product. This is very harmful and it is not allowed. False positives are just the opposite. Treating qualified products as unqualified products can be corrected by further testing. Therefore, when evaluating the reliability of fast-checking instruments, the false-negative rate should be as low as possible, preferably zero, and the control of the false-positive rate can be relaxed.

Detection limit: The minimum amount (content or concentration) of the substance that is required to confirm the presence of an analyte signal that confirms the presence of the test substance in the sample. When the confidence level is 99.7% and 95%, the detection limit is the maximum amount of the substance needed to produce a signal to noise ratio of 3 times and 2 times. The detection limit should be lower than the value of the measured object in the sample. Otherwise, the negative result of the test is unreliable.

Precision: The degree to which each measurement value matches each other when the same amount is repeatedly measured under specified conditions. Available standard deviation or relative standard deviation, range, arithmetic mean difference.

Reproducibility: The consistency between each measurement value obtained by the same analyst, using the same analytical instrument and method, when the same amount is measured several times in succession.

Reproducibility: Consistency between measured values ​​obtained by different analysts and different instruments when measuring the same quantity multiple times using the same analytical method at different or the same time.

Anti-interference: resistance to electromagnetic interference, environmental (temperature, humidity, vibration, etc.) interference, matrix (impurity) interference, etc. Because the fast inspection instruments are mostly used in the field, they are required to have strong resistance to electromagnetic, temperature, humidity, and vibration interference. The interference of the matrix (impurity) can be solved by sample processing.

Total analysis time: The time from sample acquisition to final result, including sample processing time and instrument analysis time.

For the standard sample (matrix and measured sample must be consistent) with its standard value traceable. For substances with no standard value, the results obtained by using multiple standard measurement methods in a single laboratory or multiple standards in one laboratory or multiple laboratories can be traced; multiple measurement methods can be used in multiple levels in a single laboratory, or multiple laboratories can be used. Traceability of results from a particular measurement method.