Reasons for a false positive nicotine urine test include:
There are cross-related substances or interfering substances in the tested samples. For example, the on-site screening does not clean the hair. If the drug components are attached to the surface of the hair, the on-site test result will be false positive.
Contaminated single-use plastic drinking glasses or other randomly found containers.
For example, investigators use disposable plastic water cups or other randomly found containers to extract the urine of suspected drug addicts and use reagent materials for testing. If the water cups or containers containing urine are contaminated, it may lead to false positives in on-site testing.