Biochemistry Analyzer Working Principle



Biochemical analysis instruments have continuously increased in demand with the advancement of science and technology. It is an essential reference for preventing and treating diseases as well as providing a scientific basis for their diagnosis. A variety of tests can be quickly and accurately performed with the help of this device. These include liver function tests, kidney function tests, blood glucose tests, lipid analysis tests, and other biochemical tests. In today’s market, there are many biochemical analyzers available, and people are attracted to them because of their increased practicality. For example, urinary creatinine can be measured to assess the kidneys’ filtration capacity using this type of analyzer. They are also used at the point of care, such as in physicians’ offices and at the bedside of patients. The most common types of analytical substances are enzymes, substrates, electrolytes, specific proteins, and drugs of abuse and therapeutics.

What is a Biochemistry Analyzer?

A biochemistry analyzer is medical lab equipment that conducts tests on blood, plasma, cerebrospinal fluid, or urine and helps to study and evaluate the characteristics and chemical components of the test sample. It is widely used in the medical industry for diagnosis and research purposes. The study and assessment of these liquids are very helpful in the diagnosis of various diseases and abnormalities that need medical attention. They are capable of performing over 100 types of analysis and their application can be found in the fields like immunology, endocrinology, toxicology, and oncology.

A Brief History

The first commercially available clinical sample analysis device came into play in 1959 when Hans Baruch invented the ‘Robot Chemist’. The AutoAnalyzer is an early example of an automated chemistry analyzer using a special flow technique named “continuous flow analysis (CFA)”, invented in 1957 by Leonard Skeggs, Ph.D. and first made by the Technicon Corporation. The first applications were for clinical (medical) analysis. The AutoAnalyzer profoundly changed the character of the chemical testing laboratory by allowing significant increases in the number of samples that could be processed. Talking of the automated versions, Technicon was the first company to successfully produce the world’s first fully automated biochemistry analyzer in 1957. Since then, various models and modifications of fully automated biochemistry analyzers have been emerging. This was a very important step toward the automation of clinical biochemical tests in hospitals.

Parts of the Biochemistry Analyzer

The parts of the Biochemistry analyzer vary from model to model but the most basic components are:

  • Sampler: The smaller holds the batch of samples that are brought in for sampling and is in the form of a circular tray that is rotated in intervals. It contains a sampling probe that is connected to the pump unit and has a pipette attached to it that draws the samples from each tube and transfers the drawn sample to another vial for mixing and then later for analysis. In fully automatic versions, pressure sensors are pre-installed to determine and draw the accurate amount of sample into the pipette.

  • Proportionating Pump Unit: This unit regulates the flow rates of all the liquids (reagents and samples) and eliminates the need for individual pipettes of different sizes used in the manual method. A series of rollers pass in the plastic pump tubes, producing a peristaltic action that helps in pumping action. A large number of color-coded tubes are available to choose from to adjust the pumping during the sampling process.
  • Dialyzer Assembly: It separates small and large molecules in a sample by allowing it to pass through a semi-permeable membrane. The rate of dialysis is dependent upon the temperature, although complete separation is rarely achieved. The liquid moves from the sample side to the recipient side and it must be assured that the two streams flow in the same direction.
  • Constant Temperature Module: It functions to maintain a constant reaction temperature for a particular amount of time to bring the required chemical change under certain conditions. It contains an incubator bath which further consists of a delay coil, mounted on an oil bath. Most baths are set at 35 or 95-degree celsius, but some have adjustable thermoregulators that allow a rise of 120 degrees as well. The change in the temperature is measured by the calorimeter.
  • Flow through Calorimeter: It measures the intensity of color produced by the sample. There are single and double-beam spectrophotometers used according to the model of the device. It combines with interference filters to select a wavelength produced by the color. This wavelength is then amplified and displayed.
  • Recorder Assembly: It is used to record the ratio of the responses which are directly proportional to the intensity of light that reaches the detectors. It then sends the data to the CPU and the data is displayed after the analysis.

Biochemistry Analyzer Working Principle


A fully automatic biochemistry analyzer uses spectrophotometry or colorimetry principle. Firstly, the light is passed through a monochromator that divides the complex light into monochromatic light. A sample solution is passed through a colorimetric cell by monochromatic light of a specific wavelength. Signal processing systems analyze the electrical signals generated by the photoelectric converter. According to the working mode selected by the user, the computer processes calculates, analyzes, and saves the measurement data. At the same time, the printer prints out all results. In the end, the cuvette and pipeline are clear after each group of samples has been measured. This principle states that when monochromatic light passes through a colored solution, some wavelength is absorbed and is related to color density. The amount of light absorbed or transmitted by the solution is determined by Lambert’s law.

How to operate a Biochemistry Analyzer

The operation of the biochemistry analyzer depends upon the capacity and type of analyzer. In the case of a semi-automatic analyzer, only one sample is analyzed at a time, in a fully automatic analyzer has two tanks.

  • The reagent is pipetted out manually or through an automatic arm in the case of automatic biochemistry analyzers with the desired dose of analysis.
  • The exact volume of reagent needed to perform the test is measured. The test tubes are placed in the slots and enclosed to prevent spilling or contamination.
  • The barcode on the tube is faced outward and the barcode system allows the device to recognize the tube.
  • A medical dispenser collects a certain amount of sample and sends it over to the reaction tray once the tray is loaded with a sample.
  • Following this, reagents are released into the reaction vessel after a certain amount of water is used to rinse the dispenser.
  • Flow cells or calorimeters are used to prepare a freshly prepared mixture. While the mixture is in the reaction vessel, the absorbance can be determined using a calorimeter.
  • A flow cell is a device that measures the absorbance of a mixture by sending it through a calorimeter. Analyzers can then calculate relevant concentrations in this manner.

Types of Biochemistry Analyzer

1) Semi-automatic biochemical analyzer

These are the analyzers in which some of the steps of the process ( such as addition, holding, analyzing, and recording) have to be manually performed. There are two main processes followed in a semi-automatic biochemistry analyzer, optical technique, and electrochemical technique. These are more practical for use in smaller practices and labs where a lower sample number is evaluated. Since the samples and reagents are not pre-prepared in the case of semi-automatic analyzers, it provides great flexibility in cases where there are different types of tests to be performed with different reagents each time.

2) Fully automatic biochemical analyzer

In this type of analyzer, the machine performs all the functions. The only task that has to be done by the operator is to allot a particular position to the sample in the machine. They also have to start and select the program that the analyzer needs to perform and the rest is taken care of. The test is completed and the report is printed without any human intervention.

There are other types of classifications as well-

According to the structure and principle of a biochemical analyzer

1) Continuous flow type (pipeline type)

These are the first generation of automatic analyzers where the chemical reaction happening between the reagent and the sample is done in the same pipeline and is completed after the item has been determined.

2) Discrete

As the name suggests, the chemical reactions occurring here between the reagent and the sample are completed in separate reaction cups.

3) Centrifugal

In centrifugal analyzers, the reagent and the sample are mixed with each other to bring about a chemical reaction using centrifugal force. These types of analyzers are more efficient because all the steps including mixing, reaction, and detection are done simultaneously, and hence, there is no delay.

4) Dry film type

This type of analyzer gives the benefit of portability from one place to another. It is also very quick in its function. The reagents to be mixed are in the solid phase of a film. This means that each sample that has to be tested is added dropwise on the corresponding test strip/film.

5) Bag type

Here instead of the films, the reaction and colorimetric cups are replaced by reagent bags. Even the samples that have to be measured are measured in separate reagent bags.

According to the matching of reagents and instruments.
1) Closed system

These are brand-specific analyzers meaning that the reagents and the equipment used is only compatible with a specific brand of reagents. Other reagents from different manufacturers cannot be used.

2) Open system

The reagents and instruments are sold separately and they can be interchanged for a different manufacturer. The reagent brand is not specified in these types of analyzers and hence the technician is free to choose the brand themselves.

According to the biochemical analyzer reaction principle.
1) Wet biochemical analyzer

The analyzer is based on the Lambert-beer law. This law states that there is a linear relationship between the concentration and the absorbance of the solution, with the help of which, the concentration of a solution to be calculated is measured. The carrier is an aqueous solution and an incident light is passed through it. The light is absorbed by the colored reaction products and then attenuated eventually. Hence the concentration is measured by measuring the amount of absorption.

2) Dry biochemistry analyzer

This uses the solid-phase chemistry principle where a solid reagent is used with a multilayer film. The reagent carrier is solidified in a special structure and the liquid sample is added directly to this reagent carrier. The water in the sample is used as a solvent to dissolve the solidified carrier. The components undergo a chemical reaction after combination and the concentration is determined using an analytical method.

Advantages of a Biochemistry Analyzer

  • The repetitive tasks of the process are eliminated
  • Easy insertion of samples and automation-friendly design
  • Enables early diagnosis of a disease
  • Provides an immediate report and hence reduces patient’s waiting time
  • Provides great accuracy when it comes to performing the tests (given that the maintenance is proper)
  • Fosters the product innovation prospects
  • Improves patient care
  • Increased efficiency
  • Very economical
  • Capable of analyzing multiple samples at the same time
  • Gives a measure of the progress of the patient’s disease

Limitations of the Biochemistry Analyzer

  • The reagent and samples are required in a large amount
  • The facility to calibrate it from time to time is not available
  • Multistep calibration is not very accessible
  • Limited data storage facility
  • Chances of human errors especially in semi-automated analyzers
  • Auto dilution facility is not available in some analyzers
  • Flow cell being blocked by dirt bubble
  • Chances of error during sample collection
  • Error due to incorrect sample and reagent preservation

Applications of Biochemistry Analyzer

  • To detect and monitor various diseases by analysis of chemical reactions and associating them with the symptoms
  • Used for research purposes and in pharmaceutical companies
  • Used for determining the functions of the biomolecules that are present within the cells
  • Used to detect and label DNA molecules in a sample
  • Used in clinics to determine antigen-antibody relationships
  • Used in hospital labs to perform several tests
  • To measure the concentration of a substance in the sample
  • Increase safety during the procedure

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