It can't be emphasized enough that the quality of drug testing and the ability of a laboratory to detect drugs in a specimen is dependent of the quality of the sample provided. This starts with the collection of the sample at the collection site and the handling of the sample from that point forward through the analysis and long term storage.
The first step in the testing process is the collection of the sample. This should ideally be accomplished by an observed collection in which the collector actually witnesses the sample coming from the donor's body. This is easily accomplished when hair and oral fluid samples are utilized but can be more problematic when urine samples are collected. Collectors most often have to rely on the condition of the urine sample (temperature, color, etc.) to deterimine the acceptability of the urine provided. This is not an issue when the collector can personally cut a donor's hair or collect an oral fluid sample.
Most forensic toxicologists recommend that a digital photograph be taken of the donor and include this photo in the laboratory report.
A chain-of-custody should be initiated at the time of specimen collection in which the collector and donor certify the integrity of the sample and the actual handling of the sample. This chain-of-custody document is secured along with the sample and forwarded to the laboratory.
In the laboratory, the chain-of-custody documentation is maintained throughout the testing and storage of the sample.
By following this protocol the collector and laboratory can certify the integrity of the sample handling from collection to reporting and disposal. This information is critical should the need to support test findings in a court of law become required.