We offer separate tests for each drug and 5 panel test cards. In situations where the treatment professional knows the subject's drug of choice, testing for all drugs is a waste of resources. Indeed, marijuana use can be detected in urine for as long as 30 days, while other drugs of abuse can be detected for only 2-4 days. The same technology is used in home pregnancy tests. The same type of urine screens are used by employers, government agencies, correction facilities, and probation offices.
Immunoassays use antibodies to detect the presence of drugs.
An antibody is a protein that will react only when combined with a specific substance or very similar substances. In using immunoassays in drug testing, the targeted drug acts as the antigen. The tag is the material that shows the red color on the test strip. The tagged antigen and antibodies are chemically planted on the test strip. The untagged antigen would then have to compete with the tagged antigen to react with the antibodies.