In an attempt to avoid detection of illicit drug use, some people who are asked to give a urine sample for drug screening will attempt to substitute the urine of another person or adulterate their urine specimens, using either commercially available adulterants or home-brew recipes. In settings where the urine drug screen result may be used for employment or legal actions, procedures to minimize the chance that an adulterated sample is being submitted may be required. These include measuring the temperature or pH of the urine immediately following voiding and using tamper-proof containers. The most commonly used test method for screening urine for drugs of abuse is immunoassay. In larger laboratories, the tests are often performed on the highly automated analyzers which also perform other urine and blood chemistries.
Methods are also available for several smaller batch-type chemistry analyzers.
Radioimmunoassays can be used for large batches of samples. A number of single use devices incorporating immunoassays and designed to be used outside of the traditional laboratory are also available. These devices require FDA approval to be sold in the United States, and their use in non-medical environments such as workplaces and halfway houses for criminals may be regulated by state laws. They are generally acceptable for use in the office practice environment. Some home use drug testing kits are also being sold.