Which test measures the concentration of a substance based on color change?

The colorimetric test is a method used to measure the concentration of a substance by observing the change in color that occurs when a reagent reacts with that substance. This technique is widely employed in various fields, including environmental testing, because it's relatively simple and cost-effective.

In a colorimetric test, a sample is treated with specific reagents that will react with the substance of interest. As the reaction occurs, the intensity of the color produced correlates with the concentration of the substance being measured. By using a spectrophotometer or a color comparator, the intensity of the color can be quantified, allowing for the calculation of the concentration of the target substance based on calibration standards.

This method is particularly effective in testing for chemical pollutants in water, soil, and other environmental media. The importance of the colorimetric test in environmental health lies in its ability to provide rapid and reliable quantitative data essential for monitoring and evaluating the quality of environmental samples.

Other methods mentioned, such as the DPD test, are actually a type of colorimetric test specifically designed for determining chlorine levels in water. The syringalazine test is not related to concentration measurement through color change but is used in biochemical assays. The chain of custody refers to the protocols for