The concentration of the 13 drugs of abuse and cannabinoids were calculated based on the calibration curve corrected by internal standards. Figure shows the concentrations found in positive urine samples for cocaine and metabolites, concentration ranging from 472.5-12'963 ng/ml for cocaine. The parent drug cocaine can be easily hydrolyzed to BZE (2668-17'379 ng/ml) or EME (5247-23'962 ng/ml), even from an external source of contamination. Therefore, the detection of metabolites NCOC and ECOC formed by a different pathway is required to confirm the drug intake. ECOC was found on the range 48.2-2104 ng/ml, this particular toxic metabolite is formed with the simultaneous consumption of alcohol. NCOC was found ranging from 136.5-736.2 ng/ml and was distinguished from its isomeric pair BZE in the DMS dimension with a resolution of 12.4 under the optimized LC and DMS conditions.