Fast and sensitive analysis of drug residues in water using on line SPE-UHPLC-MS/MS with ultra-fast polarity switching

As monitoring of drug residue in drinking and surface water is becoming of major concern in western countries, the environmental laboratories must face the increase in analysis request as well as the increase in the number of compounds to be screened. In parallel, as long as no consensus as been found on regulatory reporting levels, the assay sensitivity must be very high to not miss any compound. Thus, laboratories need a simple, rapid, reliable, sensitive and cost effective method to screen and to accurately quantify drug residues in a variety of water samples. A method was then set up to fulfill these requirements. On line SPE is a useful tool to enable large sample volume injections. But due to the chemical diversity of target compounds, sample clean up cannot be pushed too far to not lose polar compounds. Then matrix effect or ion suppression can be problematic for accurate quantification. Then, a very sensitive Mass Spectrometer as well as very efficient chromatography were necessary to compensate the relatively low sample volume injection.
An innovative SPE set up was developed to combine low pressure on line SPE and high pressure UHPLC analysis.