Interpreting Results
A red colored line should be observed in the control region marked C to indicate the test is performing properly. If no red line appears in the control region, the test is invalid and should be discarded and the operator should perform another test using a new test kit. A red colored line observed in the test region indicates a presumptive negative test result. The color and density of the red line may vary in the control and test regions. A presumptive positive test result occurs if no red line appears in the test region.
The drug residue surface test provides qualitative preliminary results, which only indicates the presumptive presence of the drug in a residue or substance. It does not measure drug levels.