False negative judgment: There are many reasons for false negative results, mainly reflected in the failure of FAM amplification curve, including sample inhibition, nucleic acid extraction failure, gene mutation and instrument failure. At present, domestic mainstream PCR reagents do not have the function of internal standard monitoring. The FAM amplification curve used to detect the target gene is used for both quantitative and qualitative purposes (to judge the yin and yang), so the quality of the FAM amplification curve is very critical. For such reagents without internal standard, it is recommended to combine the results of hepatitis B serum markers (five quantitative/qualitative results) to judge the yin and yang. Even if the FAM curve is amplified, this result should also be referred to, especially the result of E antigen. At the same time, for reagents with competitive internal standard monitoring function, the following four conditions can occur: if FAM is not amplified, it is marked with amplification: the result is normal, and the sample is judged to be negative; If FAM is not amplified and internal standard is not amplified: the result is abnormal, which may be caused by the failure of nucleic acid extraction or inhibition, the experiment must be repeated; If FAM is amplified, it is labeled with amplification: the result is normal, because the nucleic acid to be tested and the internal standard are amplified under the same reaction system; If FAM is amplified, but the internal standard is not amplified: the results are normal, and strong positive samples will inhibit the amplification of the internal standard, resulting in weak or negative internal standard results. False positive judgment (how to judge): There are few false positive results in clinical PCR testing, including reagent pollution, aerosol pollution, operation pollution, amplification product pollution, non-specific amplification, consumables pollution, etc., so it is recommended that a negative control must be made to monitor whether there is pollution.

In vitro diagnostic reagent products can be broadly divided into clinical chemistry, hematology, microbiology, immunology and other categories. Among them, clinical chemistry has the largest market share, nearly 40%; The second is immunology market, accounting for about 35%. Immunodiagnostic reagents are qualitative or quantitative diagnostic reagents based on the specific reaction of antigen and antibody. Such reagents have the fastest development in all diagnostic reagent products, no matter in technology or market. According to the diagnosis category, it can also be divided into infectious disease, endocrine, tumor, drug detection, immunology, blood type identification, etc. It is estimated that immunodiagnostic reagents will gradually replace clinical chemical reagents and become the mainstream of diagnostic reagents in the future. With the change of external factors, diagnostic reagents will not only become more diversified, but also develop towards household diagnostic reagents with strong specificity, high sensitivity, low price, simple use and diagnostic automation. Diagnostic reagents can be used in blood banks, hospitals, test centers, families, clinics and other departments. The product forms of diagnostic reagents are different due to different purposes. Diagnostic reagents are mainly used in hospitals and test centers, followed by families. The household diagnostic agent has the characteristics of simple, convenient and fast operation, and is suitable for those who have not received professional training. Diagnostic reagents such as pregnancy test, ovulation, blood sugar and urine used in general families belong to this kind of reagents. The proportion of such reagents in the overall market is not high, accounting for only about 9%. However, with the acceleration of people's pace of life, people pay more attention to efficiency, so such reagents are growing every year.        
Although diagnostic reagents currently account for only 25% of the biotechnology industry, they have a great impact on current medical diagnosis. As genetic engineering, gene recombination, single antibody and other biotechnology are constantly used to develop diagnostic reagents, in addition to increasing the sensitivity and specificity of reagents, it also makes it possible or rapid to diagnose infectious diseases, tumors or genetic abnormalities that were impossible or time-consuming in the past. In addition, the combination with automated analytical instruments or electronic technology not only makes these accurate diagnoses enter the clinical routine diagnosis stage from the research stage, but also shortens the distance between medical treatment and diagnosis.

Diagnostic reagents can be divided into two categories: in vivo diagnostic reagents and in vitro diagnostic reagents. It is usually a reagent for detection through the reaction between antigen and antibody. A: Classification of in vitro diagnostic reagents:
1、 In vitro biological diagnostic reagents managed by drugs include:
1. Blood type and tissue matching reagents;   
2. Microbial antigen, antibody and nucleic acid detection reagents;   
3. Tumor marker reagents;   
4. Immunohistochemical and human tissue cell reagents;   
5. Human gene detection reagents;   
6. Biochips;   
7. Allergic diagnostic reagents.   
2、 In vitro reagents managed by medical devices include:
1. Clinical basic laboratory reagents;   
2. Clinical chemical reagents;   
3. Reagents for blood gas and electrolyte determination;   
4. Vitamin testing reagents;   
5. Cytohistochemical staining agents;   
6. Autoimmune diagnostic reagents;   
7. Microbiological test reagents.
B: According to medical test items, clinical diagnostic reagents can be roughly divided into clinical chemical test reagents, immunological and serological test reagents, hematological and cytogenetic test reagents, microbiological test reagents, body fluid excreta and exfoliated cells test reagents, gene diagnostic test reagents, etc. Among them, clinical chemistry has the largest market share, nearly 34%; The second is immunology market, accounting for 29%. New immunodiagnostic reagents and genetic diagnostic reagents were developed in the late 1980s. They are the fastest growing diagnostic reagents in both technology and market.   
■ Clinical biochemical reagents
Clinical biochemical reagents mainly include several categories of products for the determination of enzymes, sugars, lipids, proteins and non protein nitrogen, inorganic elements, liver function, clinical chemical control serum, etc. They are mainly used to cooperate with manual, semi-automatic and general full-automatic biochemical analyzers and other instruments for detection, with single reagent, liquid dual reagent, dry powder dual reagent, chemical method reagent, standard products and other specifications. At the same time, all manufacturers provide testing room Quality control serum series for indoor quality control.   
■ Immunodiagnostic reagents
Immunodiagnostic reagents have the most varieties in diagnostic kits, and can be divided into infectious diseases, endocrine, tumor, drug detection, blood group identification, etc. according to the diagnostic category. From the perspective of results, it can be divided into EIA, colloidal gold, chemiluminescence, isotopes and other different types of reagents. Among them, radioimmunoassay reagents have been eliminated in the international market due to their environmental pollution, and a small amount of them are still used in China.     
■ Molecular diagnostic reagents
Molecular diagnostic reagents mainly include nucleic acid amplification technology (PCR) products that have been used in clinic and gene chip products that are currently being vigorously researched and developed at home and abroad. PCR products have high sensitivity, strong specificity, short diagnosis window, and can be used for qualitative and quantitative detection. They have been widely used for detection of hepatitis, sexually transmitted diseases, lung infectious diseases, eugenics, genetic disease genes, tumors, etc. However, due to market chaos and cross contamination, the Ministry of Health has strictly prohibited the clinical application of fluorescent electrophoresis qualitative PCR reagents, At present, the State Food and Drug Administration has approved a small number of hybrid semi quantitative and quantitative kits that have solved cross contamination. Gene chip is a combination of molecular biology, microelectronics, computers and other disciplines. It integrates a variety of modern high precision and cutting-edge technologies, and is praised by experts as the ultimate product in the diagnostic industry. However, it has high costs and is difficult to develop. At present, there are few types of products, which are only used for scientific research, drug screening and other purposes.

According to the health documents "Notice on the Batch and National Verification of In Vitro Immunodiagnostic Reagents for Blood Sample Testing of Blood Donors" (Weifa No. 10, 1994), "Notice on the Fixed Point Production of Anti A and Anti B Blood Grouping Reagents" (Weiyao No. 26, 1995), there are five kinds of blood source screening reagents prescribed by the national law: 1, A, B, O blood typing reagents; 2. Hepatitis B surface antigen ELISA reagent; 3. Hepatitis C virus antibody ELISA reagent; 4. HIV antibody ELISA reagent; 5. Syphilis diagnostic reagent.