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SAMPLING

المؤلف:  Max M. Houck، Jay A. Siegel

المصدر:  Fundamentals of Forensic Science

الجزء والصفحة:  361

2026-08-11

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SAMPLING

The types of samples taken from the body for drug identification are dictated by the condition of the body and the most likely place for the drug to congregate. If the per son is alive, then blood, urine, and, increasingly, hair are the preferred samples. If the person is dead then all of the above may be available. In addition, other tissues such as brain, liver, vitreous humor (eyes), or spinal fluid can be used. If the person took the drug and then died shortly thereafter, some of the undigested or partially digested drug may remain in the stomach. Urine concentrations of drugs and metabolites may be much greater than blood and so urine makes an ideal medium for screening for most drugs. On the other hand, the concentration of the drug in urine may not cor relate well with blood concentrations and using urine concentrations may lead to misleading conclusions about the magnitude of the drug’s effects. Therefore, it is usually good scientific practice to use urine samples to screen for the possible presence of a drug, but to use blood for determination of the concentration of the drug and for confirmation of its presence. In the past few years, hair has become an increasingly important specimen for drug analysis. Unlike blood or urine, hair can trap and hold drugs for as long as the hair is on the body, thus yielding information about drug use patterns and frequency of ingestion. Caution must be used in hair analysis for drugs owing to the possibilities for direct uptake by hair from the outside and to the effects on hair treatments such as bleaching on drug concentrations. The subject of using hair for the analysis of certain drugs will be discussed further in the section on “Drug Testing in the Workplace.