1. End-point method (endessay): It is completely converted into a product, and the reaction is no longer carried out to reach the end point. The absorbance at the end of the reaction is used to calculate the concentration of the tested substance. In biochemical tests, except for enzymes, BUN, and CRE, the end point method is almost used to determine the end point test.
One-point end-point method: Take the absorbance of one point when the reaction reaches the end point to calculate the detection result of the biochemistry fully automatic machine.
Two-point endpoint method: take the absorbance of one point before the reaction has started, and then take the absorbance of the second point when the reaction reaches the end point.
The difference between the absorbance at the second point minus the absorbance at the first point is used to calculate the result, which is mainly used to deduct reagents and sample blanks to ensure the accuracy of the results, and is generally used for double reagents.
2. Fixed time method (two-point method): It is to take the difference between two points in the reaction to calculate the result. These two points are neither the starting point nor the end point of the reaction, and are mainly used to detect some non-specific items. such as creatinine.
3. Continuous monitoring method (kinetic method, rate method): when a person uses an human fully automatic biochemistry analyzer to measure the activity of the enzyme or the metabolite of the enzyme, the absorbance value of the linear change in the reaction curve is continuously taken to calculate the result. The difference in absorbance between points in linear time is zero, so it is also called a zero-order reaction.
When purchasing ACA instruments for medical units at all levels, the following points should be considered: the applicability of the model, the performance-price ratio, the openness of reagents, regional differences, and after-sales technical support.
Among them, the applicability of the model means that the purchasing unit should choose an ACA system slightly larger than the current workload requirement according to the actual situation to meet the requirements of the unit's future development.
At the same time, considering its own economic strength, it strives to be in place in one step, and it will not be eliminated within the 7-8 year life cycle of the fully automatic biochemistry analyzer, which also reflects the requirements of the performance-price ratio.
For example, various hospitals should purchase ACA models with 1,000 tests/hour, or they can be expanded to more than 1,000 tests/hour to meet clinical needs.
It is not easy to generalize because of the two issues of regional differences and after-sales technical support involve a wide range of issues. The main consideration should be: the sales status of the model in the region, the number of existing machines of the same type and the same type, and the reputation of the sellers and manufacturers.
Large and medium-sized cities have more concentrated sales and agents, and maintenance and follow-up support can be guaranteed. It is important to consider purchasing a fully automatic biochemistry analyzer with better performance and price.
Small cities and township medical units should consider using multi-module combination instruments that can be used independently. Once some of the modules fail, the remaining modules can still operate normally, so as to ensure the normal development of scientific research and medical care.
Of course, we should pay attention to whether each module of the instrument is independent when purchasing, and the common module is simple enough and not prone to failure. Experience tells us that the less common parts of a modular fully automatic biochemistry analyzer, the greater the possibility of independent operation.
The purchase of instruments is a complex project, and each entity should conduct serious research and open bidding, and must not cause unnecessary losses due to tiny mistakes.