Teststreifen

Teststreifen, or test strips, are disposable strips used to determine the presence or concentration of substances in liquids or gases by applying a sample to a reagent-impregnated pad. They consist of a backing material, typically plastic, with one or more pads that contain chemical reagents. When the strip is dipped into a sample or the sample is touched to the pad, a reaction occurs that causes a detectable signal, usually a color change, but in some cases an electrochemical signal. The results can be qualitative (positive/negative), semi-quantitative (color scale), or quantitative when read with a meter or smartphone app.

Common types and applications include urinalysis strips for medical diagnostics, pH strips for acidity/alkalinity, and strips for glucose, ketones, proteins, nitrites, and leukocytes in clinical or home testing. Other strips are used in water quality (chlorine, hardness), soil or plant nutrient testing, and environmental monitoring. Lateral flow immunoassay strips, a related category, use antibody-based detection to indicate the presence of specific biomolecules and are widely used in rapid tests.

Construction and reading: strips may feature multiple test pads on a single strip, each corresponding to a different analyte. Reading can be by eye against a color chart in standard lighting or with a dedicated reader that measures color intensity or electrical signals. Proper storage, handling, and adherence to the expiration date are important to maintain accuracy.

Limitations: results are often semi-quantitative and may be influenced by sample quality, timing, temperature, and interfering substances. For precise measurements, confirmatory laboratory methods are used.