Indications of prohibited substances or their metabolites detected in a biological sample, such as urine, blood, or hair, deviate from expected baseline values. For instance, the presence of amphetamines in a urine sample when none were prescribed would be considered a deviation. This deviation can be either quantitative, exceeding an established threshold, or qualitative, indicating the presence of a substance not expected to be found.
Accurate and reliable identification of unexpected substances in biological samples is critical for various applications, from maintaining workplace safety and ensuring fair competition in sports to supporting clinical diagnoses and monitoring treatment efficacy. Historically, testing methodologies have evolved significantly, from rudimentary tests with limited accuracy to sophisticated chromatographic and spectrometric techniques capable of detecting trace amounts of diverse compounds. This evolution reflects the increasing demand for precision and reliability in identifying deviations in biological samples.