تسجيل الدخول

تسجيل

Sample adulteration

المؤلف:  Sue Jickells , Adam Negrusz (Editors)

المصدر:  Clarkes Analytical Forensic Toxicology

الجزء والصفحة:  390

2026-11-07

63

Sample adulteration

Specimen donors (i.e. patients, employees, detainees) may not want the immunoassay drug screen to perform correctly and may take steps to adulterate their specimen. This is largely a problem associated with screening of urine for drugs of abuse; hair, blood and saliva are less likely to be adulterated. Steps to counter this problem include observing the collection of the sample, together with physical and chemical tests to confirm that the sample is voided freshly and from the individual being tested. Tests include measurement of sample temperature at the point of collection, on-site or laboratory tests of pH, relative density and urinary creatinine concentration. More specific tests can be performed for particular adulterants. The effect of sample adulteration differs depending on the assay type. Some assays produce false-negative results, whereas others produce artificially elevated results. The key to the successful application of immunoassay as part of a testing regimen is knowledge of the characteristics of the assay in use and knowledge of the limitations as well as the benefits of each of the many variants of the method.