LIQUID-SOLID EXTRACTION AND FAST-ATOM-BOMBARDMENT HIGH-RESOLUTION MASS-SPECTROMETRY FOR THE DETERMINATION OF HYDROXYATRAZINE IN WATER AT LOW-PPT LEVELS

Parts-per-trillion levels of hydroxyatrazine (HA) have been quantitati vely extracted and eluted from water by liquid-solid extraction with a graphitized carbon-black cartridge. Recoveries of HA (> 80%) for this procedure are superior to those obtained when a C-18 cartridge or liq uid-liquid extraction with dichloromethane are used. Quantification of HA at picogram levels was accomplished by using isotope dilution and fast atom bombardment high resolution mass spectrometry. No significan t interfering spectral background occurs at the masses of interest, th ose of the [M + H](+) ions of both the analyte and the internal standa rd, when the liquid matrix is 3:1 dithiothreitol/dithioerythritol. Aqu eous samples were fortified with C-13(3)-labeled hydroxyatrazine ([C-1 3(3)]HA), and sample extracts were analyzed by recording the mass prof iles of the target ions. Identification of HA is based on the exact ma ss of the [M + H](+) ion, and confirmation is by tandem mass spectrome try (FAB-MS/MS) analysis. The method precision in relative standard de viation is 10%, and the accuracy in relative error is <10% for seven s tandard water samples containing HA at 100 parts per trillion. The met hod has been used successfully for the first time for the determinatio n of HA and for the simultaneous determination of HA and atrazine, its parent compound, in groundwater.