Eliminating Solid Phase Extraction with Large-Volume Injection LC/MS/MS: Analysis of Illicit and Legal Drugs and Human Urine Indicators in US Wastewaters

Abstract

Large-volume (1800 microL) injection (LVI) followed by liquid chromatography/tandem mass spectrometry was developed and optimized to eliminate the need for off- and on-line solid phase extraction as a sample preparation step. Centrifugation of raw municipal influent followed by LVI was optimized for the routine determination of illicit drugs and related substances in municipal wastewaters. The accuracy of the method is demonstrated by standard addition for analytes with concentrations ranging from 4 to 3,500,000 ng/L. Precision, as indicated by relative standard deviation is <12% within a day and < or =20% for between-days for analytes with corresponding stable-isotope-labeled internal standards. Instrumental detection limits range from 0.5 to 4 ng/L while lower limits of quantification range from 2.5 to 10 ng/L The method is demonstrated on wastewater treatment plant influents (24 h, flow-normalized) collected from seven municipalities located in the US. Methamphetamine concentrations and loads are the greatest yet reported while cocaine concentrations and index loads are similar to European locations. Creatinine is introduced as human urine indicatorthat can be potentially used as an alternative to population estimates for indexing illicit drug loads for different municipalities.