Ultratrace determination of atrazine and its six major degradation products in water by solid-phase extraction and liquid chromatography electrospray mass spectrometry

Due to the widespread use of atrazine, this herbicide and its degradation products (DPs) can contaminate waters destined for human consumption. The overall impact of these compounds in aquatic ecosystems has not yet been assessed. This paper describes a very sensitive and specific method for ultratrace determination of atrazine and its six major DPs in environmental waters. This method is based upon solid-phase extraction with a new example of graphitized carbon black (Carbograph 4) followed by electrospray (ES) liquid chromatography-mass spectrometry (LC-MS). On extracting from 1 L of river water and 4 L of both groundwater and drinking water, analyte recoveries were better than 80%. Day-to-day precision was 2.9-9.8% at 25 ng/L (full-scan acquisition) and 2.3-7.7% at 3 ng/L (two-ion SIM acquisition). For all the analytes considered, raising the skimmer cone voltage in the desolvation chamber of the ES/MS system had the double effect of producing diagnostic fragment ions and enhancing the ion signal strength. In this way, highly specific full-scan LC-MS analysis of the seven analytes could be performed at levels down to 40-300 ng/L in river water samples. Time-scheduled selected ion monitoring of the intact molecular ion plus one related fragment ion could afford specific determination of the analytes at sub-nanogram per liter levels in groundwaters and drinking waters. A short survey conducted by analyzing some river (Tiber) water samples ascertained the presence of all the atrazine DPs, except DEDIA, at a few nanogram per liter levels.