The Trinder colorimetric reaction is widely used for determining which analyte?

• A. Acetaminophen
• B. Propoxyphene
• C. Salicylate
• D. Barbiturate

Answer: (C)

The Trinder colorimetric reaction is based on using peroxidase to form a colored dye from hydrogen peroxide in the presence of a chromogenic pair (like 4-aminoantipyrine and phenol). The hydrogen peroxide comes from an oxidase step that acts on the target analyte, so the color intensity reflects how much analyte is present.

For salicylate, an appropriate oxidase converts salicylate to products that release hydrogen peroxide. That H2O2 then drives the Trinder reaction, producing a color whose intensity is proportional to the salicylate level. This setup is widely used because it’s simple, fast, and yields a reliable, easily measured color change with common reagents.

Other substances listed aren’t typically measured this way because they require different detection methods or reagents; their routine analyses usually rely on alternative approaches rather than the Trinder colorimetric system.