Your Toxicology Testing Facility Tests Urine Samples

Your toxicology testing facility tests urine samples.New screening tests for methamphetamine and amphetamine have been added to the drug profiles.Occasionally a positive methamphetamine immunoassay screening test is followed by a negative amphetamine confirmatory test result.What might cause this discrepancy?

A) Recent use of hydrocodone would give a negative amphetamine result,as it blocks the reaction on the screening test.
B) If the specimen contained ephedrine or pseudoephedrine,it might test positively for methamphetamine but not amphetamine.
C) False-negative results are common,especially when the immunoassay is performed without prior glucuronide hydrolysis.
D) Other chemically related compounds such as pseudoephedrine have been shown to produce positive results in amphetamine immunoassays.