Automated reagent strip readers IRIS operate on which principle?

• A. Turbidimetry
• B. Reflectance photometry
• C. Nephelometry
• D. Electrophoresis

Answer: (B)

The main concept is optical colorimetric readout on a solid test pad using reflectance. Automated reagent strip readers shine light onto the reagent pad; as the pad changes color with the analyte level, the amount of light reflected back to the detector changes. The reader then converts that reflectance into a numerical value representing concentration. This approach works well for dried, surface color changes on strips, unlike techniques that depend on light passing through a liquid or on light scattering from suspensions, or methods that separate components with electric fields. Turbidimetry and nephelometry rely on how a suspension affects transmitted or scattered light, which isn’t applicable to dried strip pads, and electrophoresis involves moving particles in an electric field rather than measuring color.