colorimetric

Colorimetric refers to methods that rely on color change or color intensity to indicate the presence or concentration of a substance. In colorimetric analysis, a chemical reaction or binding event produces a colored product or alters an existing color. The measured color can be assessed by eye or quantified with an instrument such as a colorimeter or spectrophotometer by determining absorbance at specific wavelengths.

Quantitative relationship is often described by the Beer-Lambert law, which links absorbance to concentration in a defined range, enabling calibration curves.

Common formats include enzymatic assays with chromogenic substrates, indicator dyes, color-changing pH tests, and lateral flow or dipstick tests that yield a colored line or spot. Colorimetric detection is widely used in clinical laboratories, environmental tests, food safety, and education.

Advances include colorimetric sensors based on nanoparticles or microfluidic platforms, and the use of digital imaging or smartphone cameras to quantify color changes, improving objectivity and portability.

Advantages of colorimetric methods include simplicity, low cost, rapid results, and suitability for field testing and point-of-care settings. Limitations involve interference from sample color or turbidity, limited dynamic range, and dependence on lighting conditions for visual readings; often, careful calibration is required to ensure accuracy.