A new automated colorimetric method for measuring total oxidant status

Area of Science:

• Biochemistry
• Analytical Chemistry
• Clinical Diagnostics

Background:

• Oxidative stress plays a crucial role in various pathologies.
• Accurate measurement of total oxidant status (TOS) is essential for understanding oxidative stress.
• Existing methods for TOS measurement may lack automation, sensitivity, or reliability.

Purpose of the Study:

• To develop and validate a novel, automated, colorimetric method for quantifying total oxidant status (TOS).
• To establish the analytical performance characteristics of the new TOS assay.
• To assess the utility of the TOS assay in a clinical setting, such as differentiating osteoarthritis patients from healthy individuals.

Main Methods:

• The assay utilizes the oxidation of ferrous ions to ferric ions by oxidants in an acidic medium, with ferric ions detected using xylenol orange.
• The method was optimized to enhance reaction speed, prevent protein precipitation, and stabilize reagents.
• The assay was adapted for an automated analyzer and calibrated using hydrogen peroxide standards.

Main Results:

• The automated TOS assay demonstrated strong correlations with standard oxidants (hydrogen peroxide, tert-butyl hydroperoxide, cumene hydroperoxide).
• The assay exhibited linearity up to 200 µmol H2O2 Equiv./L with a precision below 3% and a low detection limit of 1.13 µmol H2O2 Equiv./L.
• Serum TOS levels were significantly higher in osteoarthritis patients compared to healthy controls, with a negative correlation to total antioxidant capacity (TAC).

Conclusions:

• The developed method is easy, stable, reliable, sensitive, inexpensive, and fully automated.
• This novel assay provides a valuable tool for measuring total oxidant status in both research and clinical settings.
• The findings highlight the potential of this assay for diagnosing and monitoring diseases associated with oxidative stress.