What is a Diluent

To dilute something is to reduce its potency, viscosity, or concentration. The definition of a diluent in immunochemistry is a liquid solution that reduces the potency of another substance or liquid. In immunoassays, using a sample or assay diluent can help reduce false positives and block matrix interferences while maintaining the assay’s clinical utility.

Due to the variability within patient samples, different blocking strategies are needed to dilute samples to achieve maximum assay performance. For immunodiagnostic assays, a false positive or false negative result can lead to a misdiagnosis of a disease or condition and improper treatment decisions. Clinicians and patients depend on the in vitro diagnostics (IVD) industry to develop high quality assays that deliver accurate results consistently.

With the increased use of antibody therapy and animal-derived products being used to treat patients, the prevalence of heterophilic antibodies, human anti-mouse antibodies (HAMA), human anti-animal antibodies (HAAA), and rheumatoid factors is becoming an increasing problem for assay developers. With immunoassays pursuing lower detection limits, multiplexing analytes, and higher sample through-put, the negative effects of heterophilic antibodies, HAMA and other matrix effects needs to be addressed.

Surmodics™ IVD Sample/Assay Diluents

Surmodics IVD’s MatrixGuard™ Diluent and Assay Diluent (Protein-Free) are the gold standard for reducing false positives in your assay. These formulations provide two options to use when different methods are needed to block matrix interferences, while maintaining the clinical utility of the assay.

For IVD kit manufacturers requiring a strong, consistent blocking diluent across a variety of assays, MatrixGuard Diluent provides unsurpassed blocking whereby matrix interferences are effectively blocked while the intended assay signal is maintained.

Unlike other diluents that either are marginally effective at blocking matrix interferences or alternatively block out true assay signal, MatrixGuard Diluent achieves the goal of maximum blockade of matrix interferences while simultaneously allowing signal to be maintained.

Assay Interference and Diluents

Interference in an immunoassay, whether enzyme-linked immunosorbent assay (ELISA), radioimmunoassay, bead-based assays, or immuno-PCR assays, has been a problem that continues to grow throughout the industry. Problems with HAMA, heterophilic antibodies, and rheumatoid factors have clinical significance as demonstrated by studies that show the prevalence of interfering proteins in patient samples may be as high as 80%.. These issues have continued to grow in prevalence due to use of therapeutic antibodies, vaccinations, blood transfusions, certain drugs derived from animals, and other sources of exposure.

Reducing Interference Through Blocking Technology

Surmodics IVD’s sample/assay diluents help to eliminate background noise and reduce false positives while maintaining the clinical utility of the assay.

Review the product inserts below for Assay Diluent (Protein-Free) and MatrixGuard Diluent to learn more about our specific recommendations for use.

Frequently Asked Questions

What Is Diluent Used for?

• A diluent is used in immunochemistry to eliminate background noise and reduce false positives.

What is the difference between Assay Diluent (SM01) and MatrixGuard Diluent (SM02)?

• MatrixGuard Diluent (SM02) contains protein and Assay Diluent (SM01) is protein-free.
• These formulations provide two options to use when different methods are needed to block matrix interferences, while maintaining the clinical utility of the assay.

What is matrix interference?

• The term “matrix” refers to the unknown components of patient’s sample other than the intended analyte. When these unknown components interfere with sample analysis, it is referred to as matrix interference. Matrix interference can lead to incorrect sample analyses and unreliable results in clinical and diagnostic immunoassays.

What are the causes of matrix interference?

• Some matrix interference can come from endogenous substances and characteristics such as salt concentration, pH, and viscosity of the solution. Substances such as heterophilic antibodies (including human anti-mouse antibodies “HAMA” and rheumatoid factor “RF”), and human anti-animal antibodies “HAAA” can play a more prominent role in matrix interference by non-specifically binding to the antibodies or analyte. While these causes of interference are diverse in nature, the Surmodics’ sample and assay diluents minimize the effects of these sources of interference.

To learn more about the utility of diluents in immunoassays or to find out what Surmodics is doing to improve these methods, explore our website or contact us today to connect directly with one of our R&D scientists.