On Site Urine Testing
On site testing of urine samples offers a preliminary test result. Specimens are collected as outlined in the preceding sections and tested in individual testing kits usually for the five major classes of drugs. Positive on site screening results must be sent to the laboratory for screening by immunoassay and, if necessary, confirmation by GC/MS. On site screening provides a rapid method for excluding the presence of drugs but, due to the lack of specificity of on-site kits, it does not provide a dependable positive result. SCI recommends regular quality control checks on negative results by correlation with the laboratory immunoassay screen.