We present an isotopic dilution direct injection reverse phase liquid chromatography-tandem mass spectrometry (RPLC/MS/MS) method for the simultaneous determination of 23 drugs of abuse, drug metabolites, and human use markers in municipal wastewater. The method places particular emphasis on cocaine; it includes eleven of its principal metabolites to facilitate assessment of routes of administration and to enhance the accuracy of estimates of cocaine consumption. Four opioids (6-acetylmorphine, morphine, hydrocodone, and oxycodone) are also included, along with five phenylamine drugs (amphetamine, methamphetamine, MDMA, MBDB, and MDEA), and two human use markers (cotinine and creatinine). The method is sufficiently sensitive to directly quantify 18 analytes in wastewater at concentrations less than 50 ng/L without pre-concentration. We have also developed a modified version of this method that incorporates solid phase extraction (SPE) to further enhance sensitivity. The method includes a confirmatory LC separation with 17 retention time shifts (selected by evaluating thirteen unique chromatographic phases), and has been tested against NIST Standard Reference Material 1511 for human drugs in urine.
Citation: Analytical Chemistry
Pub Type: Journals
reversed-phase liquid chromatography, mass spectrometry, illicit drugs, wastewater, solid phase extraction, metabolites, isotopic dilution