The Differences Between Direct and Indirect Chemiluminescence Principles

Chemiluminescence is a process in which light is emitted as a result of a chemical chemiluminescent reaction. It is widely used in immunoassays, which are tests that measure the presence or concentration of a substance in a sample using an antigen-antibody reaction. There are two main methods of chemiluminescence immunoassay: direct and indirect.

The Differences Between Direct and Indirect Chemiluminescence Principles

Direct chemiluminescence

In direct principle, the antigens or antibodies are directly labeled with a luminophore, which is a substance that produces light when activated by a chemical or physical stimulus. The most common luminophore used in direct method is acridinium ester, which emits light when oxidized by hydrogen peroxide in the presence of an alkaline solution. The amount of light produced is proportional to the amount of antigen-antibody complex formed in the reaction. Direct principle is a simple and sensitive method that does not require a secondary antibody or a substrate. 

Indirect chemiluminescence

In indirect chemiluminescence, the antigens or antibodies are labeled with an enzyme, which catalyzes the conversion of a substrate into a luminophore. The most common enzyme used in indirect method is alkaline phosphatase, which removes a phosphate group from a substrate called AMPPD, causing it to emit light. Indirect principle is a versatile method that can be used to detect various antibodies by changing the solid-phase antigen. 

The Differences Between Direct and Indirect Chemiluminescence Principles

iA1000: A direct chemiluminescence analyzer

The iA1000 Automatic Chemiluminescence Immunoassay Analyzer uses the direct chemiluminescence principle to provide accurate results. It is a fully automated system that uses magnetic separation technology to ensure high-efficient separation. Weighing only 80kg and with small dimensions, the iA1000 Analyzer is a compact and affordable tool for clinical diagnosis. If you’re interested in learning more about the iA1000, please don’t hesitate to contact us at Our team of experts would be happy to answer any questions you may have.

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