pHTests

pHTests are methods used to determine the acidity or basicity of a solution by measuring hydrogen ion activity, expressed on the pH scale from 0 to 14. Tests can be qualitative, using pH indicator strips that change color in response to acidity or basicity, or quantitative, using electronic pH meters equipped with glass electrodes to produce numerical readings. The pH scale is logarithmic; a one-unit change corresponds to a tenfold change in hydrogen ion concentration, with pH 7 regarded as neutral.

Common methods include colorimetric strips for rapid or field testing and glass electrode pH meters for precise measurements in laboratories or industrial settings. pH meters require calibration with standard buffer solutions, typically near pH 4, 7, and 10, to correct for instrumental drift and temperature effects. Temperature compensation is often built into modern meters, as temperature can influence readings. Proper preparation of the sample, such as filtering turbid liquids or removing bubbles from the measurement chamber, improves accuracy; electrode maintenance and cleaning are also important.

Applications of pH testing span water quality (drinking water, wastewater), soil testing (to guide agronomic adjustments), food and beverage processing, medical and clinical laboratories, industrial processes, and hobbyist domains like aquariums. Limitations include interference from colored or highly pigmented samples, turbidity, high ionic strength, or strong oxidizers, which can affect indicator color or electrode response. Best practices emphasize routine calibration, appropriate sample handling, and awareness of the method’s accuracy range, typically about ±0.1–0.2 pH units for meters and broader for strips.