Choosing the Right Immunoassay Analyzer

An immunoassay analyzer is used to detect and quantify the concentration of specific substances in a sample. It usually uses an antibody as a reagent: specific antigens bind to these antibodies, stimulating an immune response.

Hospitals and clinical laboratories use immunoassay analyzers to perform a variety of tests covering many medical specialties.

When choosing an immunoassay analyzer, it’s important to consider several parameters, such as the types of tests and reagents required, the device’s throughput, and whether or not automatic repetition and dilution are required.

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  • What are the different types of immunoassay analyzers?

    Immunoassay analyzers can be classified into different types according to their mode of use, reagent compatibility, or sampling mode:

    • Mode of use:
      • Automatic analyzers: The device automatically mixes the samples with reagents. These models are suitable for analyzing a large number of samples.
      • Semi-automatic analyzers: The operator mixes the samples with the reagents. These models are particularly well suited for analyzing small sample quantities. With semi-automatic analyzers, the operator manages the sequence of tests.
    • Reagent compatibility:
      • Open systems: These are compatible with reagents from a variety of brands.
      • Closed systems: These, on the other hand, are only compatible with reagents from the device manufacturer.
    • Sampling mode:
      • Random access sampling: The immunoassay analyzer accesses samples randomly, i.e. in no particular order.
      • Continuous-access (or sequential) sampling: Samples are accessed in the order in which they are positioned in the rack.

    Randox random access immunoassay analyzer

    DiaSorin automatic immunoassay analyzer

    Boditech semi-automatic immunoassay analyzer

  • What tests does an immunoassay analyzer perform?

    Immunological tests rely on the ability of an antibody to bind to a specific macromolecule known as an antigen. Immunoassays produce a detectable and measurable signal via a marker in response to this binding. Immunoassay analyzers can be used to test a wide variety of substances, including blood and its components (serum, plasma) and urine. Here are some of the molecules measured during the tests (analytes):

    • Proteins:
      • Antibodies: By measuring the amount of specific antibodies in a sample, you can infer the amount of antigens present.
      • D-dimers: These proteins are fragments of fibrin, the main component of blood clots. They appear in the blood when clots dissolve. They are involved in everything to do with inflammatory reactions, particularly in blood vessels.
      • CRP: C-reactive proteins (CRP) are synthesized by the liver when there is inflammation or infection in the body.
    • Hormones: Hormone levels can be measured to determine the amount of growth hormones or thyroid hormones present. These assays use antibodies specific to the hormones of interest.
    • Tumor markers: Certain proteins serve as tumor markers, and are used in particular for oncology applications.
  • What are the different immunological analysis techniques?

    There are several different immunoassay techniques: enzyme immunoassay (EIA or ELISA), radioimmunoassay (RIA), fluoroimmunoassay (FIA), counting immunoassay (CIA), and chemiluminescent immunoassay (CLIA).

    • Enzyme immunoassay (EIA or ELISA): In this test, the antibody is bound to an enzyme. After incubation, any antibody not bound to the target antigen is removed by washing. The antibody-enzyme bound to the target antigen can then be observed by adding a substrate to the solution.
    • Radioimmunoassay (RIA): In RIA, the reagent used is an antibody, and this antibody binds to a complementary antigen that has been labeled with a radioisotope. During incubation, it competes with the target antigen present in the sample. At the end, the sample’s radioactivity is measured.
    • Fluoroimmunoassay (FIA): Antibodies are labeled with fluorescent molecules. After incubation with the antigen, antibody-antigen complexes are isolated and the fluorescence intensity is measured.
    • Counting immunoassay (CIA): Here, polystyrene beads are coated with multiple antibodies that specifically bind to the target antigen. At the end of the incubation period with the sample, the number of beads that have not bound to the target antigen is counted.
    • Chemiluminescent immunoassay (CLIA): Here, the principle is similar to ELISA or FIA. The difference is that the luminescence observed at the end of the incubation period is caused by a chemical reaction.

    PHC CLIA immunoassay analyzer

    Dynex ELISA immunoassay analyzer

    Main Immunoassay Techniques:

    • Enzyme immunoassay (ELISA)
    • Radioimmunoassay(RIA)
    • Fluoroimmunoassay (FIA)
    • Counting immunoassay (CIA)
    • Chemiluminescent immunoassay (CLIA)
  • For what applications is an immunoassay analyzer used?

    An immunoassay analyzer can be used in a variety of applications to perform many types of tests, such as:

    • Cancer marker screening
    • Diagnosing infectious diseases (Covid-19, sexually transmitted diseases, etc.)
    • Cardiac analysis
    • Tests in the pharmaceutical industry for therapeutic monitoring of drugs
    • Drug testing
    • Allergy tests (dust mites, pollens, animal dander, food allergens, etc.)
    • For research purposes
  • What are the performance criteria for an immunoassay analyzer?

    There are many technical criteria for judging the performance of an immunoassay analyzer, such as versatility, throughput, sample capacity, minimum sample volume, and so on. Here is a list of the main performance criteria:

    • Versatility: This refers to the number of different tests the analyzer can perform. The higher the number, the more versatile the analyzer.
    • Throughput: The number of tests performed per hour. Depending on requirements and the need to analyze large quantities of samples, it may be preferable to opt for a high-speed analyzer. As a reminder, this criterion cannot be applied to semi-automatic analyzers.
    • Sample capacity: This is the number of places on the rack where samples are put.
    • Minimum sample volume: This is the smallest amount of sample at which the device can detect the presence of antibodies. The smaller the volume, the more sensitive the device and the higher its performance.
    • Number of reagent positions: This is the number of reagents that can be loaded at the same time.
    • Reaction time: Here again, depending on your needs, it may be worth opting for an analyzer with a fast reaction time. Some devices offer a reaction time of around ten minutes, with the first results available in around twenty minutes.
  • What are the different configurations for an immunoassay analyzer?

    An immunoassay analyzer is generally available in three configurations: benchtop, portable, or floor-standing.

  • What is the price range for an immunoassay analyzer?

    Depending on the brand, the number of tests available, and the type of analyzer, prices can vary from a thousand euros to tens of thousands of euros.

    Semi-automatic analyzers are generally less expensive than fully automated models.

  • Are there any risks involved in using an immunoassay analyzer?

    The use of an immunoassay analyzer presents certain risks, particularly when conducting the RIA method and handling samples. There are also risks of analysis error.

    • Conducting the RIA method: There are health risks linked to the use of radioactive substances.
    • Sample handling: Some samples may present a risk of infection and must therefore be prepared with care by laboratory staff.
    • Risks of analysis error: If the device is poorly calibrated or insufficiently accurate, this can lead to erroneous diagnoses and ultimately harm patients’ health. Hence the need for a robust quality control system to ensure the reliability of the tests carried out.
  • Does an immunoassay analyzer require special maintenance?

    A laboratory must have a quality control system with documentation detailing the maintenance of the device.

    This is necessary to meet international quality standards (NF EN ISO 15189).

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