Biochemical Analyzer: Introduction to Three Commonly Used Analysis Methods

Biochemical Analyzer: Introduction to Three Commonly Used Analysis Methods

With the continuous advancement of medical technology, biochemical analyzers, as one of the key tools for medical diagnosis, play an important role in clinical applications. Biochemical analyzers can quickly and accurately analyze the chemical components in various biological samples, providing doctors with important diagnostic basis and treatment suggestions. In this article, we will introduce the three major analysis methods commonly used in biochemical analyzers to help everyone better understand the working principle and application scenarios of this medical equipment.

There are three categories of commonly used analysis methods for biochemical analyzers, namely end-point method, fixed time method and kinetic method.
End point method:

It means that after a period of reaction, the reaction reaches equilibrium. Since the equilibrium constant of the reaction is very large, it can be considered that all substrates (test substances) are converted into products. The absorbance of the reaction solution no longer changes and is only related to the concentration of the analyte. This type of method is often called an "end-point" method, or more specifically a "balanced" method.
Single-reagent single-wavelength end-point method: add reagent (volume V) at t1, add sample (volume S) at t2, then stir and react, then start measuring the absorbance of the reaction solution, and the reaction reaches the end point at t3, t3-t2 for measuring time.
Reactivity: R=At3-At2-1×V/(V+S), or R=At3-ARBLK.
Among them: Ati is the absorbance at time i, and ARBLK is the reagent blank absorbance.
Single-reagent dual-wavelength end-point method: Basically the same as the "single-reagent single-wavelength end-point method", except that for each measurement cycle, the actual absorbance is equal to Aλ1-Aλ2.
Dual-reagent single-wavelength endpoint method: add the first reagent (volume V1) at t1, add the sample (volume S) at t2 and stir immediately, add the second reagent (volume V2) at t3 and stir immediately, and react at t4 Reach the end. t3-t2 is the incubation time, t4-t3 is the measurement time.
In the project parameters, if the reaction start time is set to 0, then the reaction degree R = absorbance at time A - double reagent blank absorbance. If the reaction start time is less than 0, then the reaction degree R=At4 - the double reagent blank absorbance - the absorbance of the set point between t3 and t2 × (V1 + S) / (V1 + S + V2). Dual-reagent dual-wavelength end-point method: Basically the same as the "dual-reagent single-wavelength end-point method", except that for each measurement cycle, the actual absorbance is equal to Aλ1-Aλ2.

Fixed time method:
Also known as the first-order kinetics method, the two-point kinetics method, etc., it means that within a certain reaction time, the reaction rate is proportional to the first power of the substrate concentration, that is, v=k[S]. As the substrate is continuously consumed, the entire reaction speed is continuously reduced, which is manifested in the smaller and smaller change in absorbance. This type of reaction takes a long time to reach equilibrium and can theoretically be monitored at any time. However, due to the complex composition of serum, the reaction is more complicated and there are many miscellaneous reactions when the reaction is just started. A delay period is required before the stable reaction period can be entered.
Add the reagent (volume V) at t1, then measure the absorbance of the reagent blank, add the sample (volume S) at t2, the reaction is stable at t3, stop monitoring the reaction at t4; t2-t3 is the delay time, t3-t4 for measuring time.
Single wavelength reactivity (single and double reagents are the same): R=At4—At3
Dual-wavelength reactivity: R = (Absorbance of main wavelength at time t4 - Absorbance of sub-wavelength at time t4) - (Absorbance of main wavelength at time t3 - Absorbance of sub-wavelength at time t3)

Dynamic method:
Also known as the zero-order kinetics method, it means that the reaction rate is proportional to the zeroth power of the substrate concentration, that is, it has nothing to do with the substrate concentration. Therefore, during the entire reaction process, the reactants can generate a certain product at a uniform speed, causing the absorbance of the measured solution to decrease or increase uniformly at a certain wavelength. The rate of decrease or increase (ΔA/min) is consistent with the measured substance. proportional to the activity or concentration. The kinetic method is also called the continuous monitoring method; it is mainly used for the determination of enzyme activity.
In fact, since the substrate concentration cannot be large enough, as the reaction proceeds and the substrate is consumed to a certain extent, the reaction rate is no longer zero order. Therefore, the zero order kinetics method is aimed at a specific time period. ;Similarly, due to the complex composition of serum, the reaction is more complicated and there are many miscellaneous reactions when the reaction is just started. A delay period is required before the stable reaction period can be entered. Each reagent manufacturer has strict regulations on these two periods.
Add the reagent (volume V) at t1, add the sample (volume S) at t2, the reaction is stable at t3, and stop monitoring the reaction at tn; t3-t2 is the delay time, and tn-t3 is the measurement time. Single wavelength reactivity (single and double reagents are the same) R = (n∑AT-∑A∑T)/[n∑T2-(∑T)2], where: n=the number of data between t3 and tn, T= Time, A=absorbance at a certain time. Dual-wavelength reactivity is basically the same as single-wavelength, except that the absorbance at a certain time is equal to the main wavelength absorbance minus the sub-wavelength absorbance.

Application scenarios
The wide application of biochemical analyzers has penetrated into many medical fields such as hospitals, clinics, and laboratories. It can not only be used for clinical diagnosis to help doctors accurately determine the type and severity of the disease, but can also be used for drug therapy monitoring, evaluating treatment effects and adjusting treatment plans. In addition, biochemical analyzers also play an important role in scientific research and the development of new drugs, making important contributions to the advancement of medical science.

Conclusion
As an important tool for medical diagnosis and scientific research, biochemical analyzers continue to promote the development and progress of medical technology. Through a variety of analysis methods such as photometry, electrochemistry and instrumental chemistry, biochemical analyzers can achieve rapid and accurate analysis of various components in biological samples, providing reliable technical support for clinical diagnosis, treatment and scientific research. It is believed that with the continuous innovation and development of technology, biochemical analyzers will play a more important role in the future and make greater contributions to human health.