Analysis of Influencing Factors of Hepatitis B Two-and-a-half Detection
The impact of sample collection and processing
1.1 The specimen is strictly hemolyzed and the serum mixed with red blood cells is easy to precipitate or adhere to the polyethylene hole and is not easy to wash. The hemoglobin remaining in the hole has peroxidase-like activity, and the color of the catalytic substrate causes false positives. Severe hemolyzed specimens Disabled.
1.2 The blood collection test tube is not washed thoroughly, and it is easy to cross-contaminate after repeated use; the plastic test tube can adsorb antigenic substances, and if the sample is placed in the plastic tube for a long time, the antigen content in the sample will decrease and cause false negative. It is best to use disposable glass test tubes or vacuum tube blood collection tubes; and use non-anticoagulant samples, heparin anticoagulated plasma will increase the OD value, which may be related to the strong negative charge of high concentration heparin, which can adsorb enzyme markers and are not easy to elute; EDTA, Enzyme inhibitors such as NaN3 can inhibit horseradish peroxidase activity in ELISA systems.
1.3 Incomplete coagulation of the specimen, normal blood starts to coagulate in 1/2~2h after collection, and complete blood clot shrinks completely in 18~24h. At work, sometimes in order to gain time for rapid detection, the serum is often forcibly separated by centrifugation before the blood has begun to coagulate, so that some fibrinogen remains in the serum. False-positive results are caused; therefore, blood samples must be fully coagulated before separating serum, or blood collection tubes with separating gel or appropriate coagulants should be added to the blood collection tubes during sample collection.