A nephelometry system for the Abbott TDx analyzer

Area of Science:

• Biochemistry
• Analytical Chemistry
• Immunology

Background:

• The Abbott TDx analyzer is a fluorescence polarization analyzer.
• Nephelometric methods are crucial for quantifying specific proteins in biological samples.
• Existing analytical methods may have limitations in terms of throughput or sample preparation.

Purpose of the Study:

• To develop a light-scattering accessory for the Abbott TDx analyzer.
• To extend the TDx analyzer's capabilities to nephelometric assays.
• To enable the quantification of specific proteins and monitoring of chromogenic reactions.

Main Methods:

• A self-contained light-scattering accessory carousel was developed for the Abbott TDx.
• Scattered light was measured at 37.5 degrees using a green-light-emitting diode (565 nm).
• Measurements were performed at quasi-equilibrium with sample blank correction and automatic antigen-excess checks.

Main Results:

• The accessory successfully extended the TDx analyzer to nephelometric methods.
• Assays for specific proteins (IgG, IgA, IgM, transferrin) were performed with good precision (CVs 3-6% within-run, 7-9% total).
• A novel nephelometric method, Scattered Energy Attenuation (SEA), was described and applied to measure calcium, total protein, iron, and bilirubin.

Conclusions:

• The developed light-scattering accessory enhances the Abbott TDx analyzer's versatility for clinical diagnostics.
• Nephelometric assays for specific proteins can be reliably performed on the modified TDx.
• The SEA method shows promise for monitoring various biochemical analytes.