Validity and Adulteration Testing
Many donors may be inclined to avoid detection of their drug use and will try to adulterate their urine specimen. Methods for avoiding detection of substance use ("tampering") include dilution of the sample with water or other liquids, substitution with a "clean" or synthetic urine specimen, and by addition of other chemicals or substances which are designed to destroy or modify any drugs present or interfere with the testing methods. Furthermore, there are devices available, including artificial devices that a donor may try to use. Information on avoiding detection and the purchase of adulteration devices are readily available on the Internet. In addition, there are several books and publications that may be purchased on this subject.
To ensure integrity of testing results, Willow labs incorporates various methods of specimen validity testing, starting from the actual collection of the specimen to the final analysis.
Several analytical parameters are used to indicate whether the sample has been adulterated. These include pH, temperature, creatinine, and specific gravity. Normal urine temperature is expected to be 90°F to 100°F within several minutes of producing a sample. Temperatures which fall outside of this range may suggest substitution. When monitoring for dilution, creatinine is measured. Creatinine levels are expected to be greater than or equal to 20 ppm. A creatinine level below this threshold suggests dilution, either directly by adding water to the sample or through excessive fluid ingestion and /or diuretics. A normal urine specimen has a specific gravity level 1.003 and a pH level between 3 and 11. Levels outside of these ranges may suggest adulteration by the addition of a foreign chemical or substance. Many available chemical adulterants include glutaraldehyde, pyridium chlorochromate, and nitrites which tend to oxidize the chemical structure of any drugs present thereby, rendering them insensitive to the initial screening assay or confirmation testing. Willow labs tests for these substances on every sample it receives. In addition to the above integrity checks Willow considers the specimen collection area to be free from water sources, prohibiting outer garments and personal belongings from the collection room, having subjects wash their hands, and direct observation of the specimen collection. Willow has a comprehensive training program for all of its specimen collectors and keeps up to date on any new devices or techniques that a donor may try and use.