Flow-injection analysis thermospray tandem mass spectrometry of triazine herbicides and some of their degradation products in surface water

A rapid procedure to determine twelve triazines and eleven of their degradation products in water samples by means of flow-injection analysis with thermospray tandem mass spectrometry (FIA-MS-MS) is described. After solid-phase extraction (SPE) of a 30 mL sample on a C18 cartridge which also effects salt removal, elution with 5 mL methanol, evaporation of the eluate to 1 mL and dilution with 0.11 M ammonium acetate solution to a final volume of 10 mL 2-5 mt are directly injected by means of FIA into the ion source of a tandem MS. Samples are first analysed with a target screening procedure in which only one characteristic product ion is acquired per compound and used to quantify. The identity of compounds in suspected samples is confirmed with a multiple reaction monitoring (MRM) procedure in which typically four product ions are analysed. All compounds show good linearity over the concentration range studied (0.05-1 mu g/L). Recoveries of the triazines are over 82% while the recoveries of the degradation products are over 60% except for hydroxy-desethyl-desisopropyl-atrazine (47%). For most compounds the repeatability of the procedure is good (RSDs < 10%) at the 0.5 mu g/L level. H-2(5)-ethylamine-atrazine is used as an internal standard to check the reproducibility of the procedure and the ionization efficiency of the compounds. Detection limits are 0.05-0.15 mu g/L for triazines and 0.20-0.45 mu g/L for degradation products. The practicability of the method is tested by the analysis of samples from a national survey on atrazine and simazine. Even with seawater samples no problems are encountered as long as solid phase extraction is applied. The results obtained from two interlaboratory studies show that data obtained with FIA-MS-MS are fully comparable to those found by means of conventional chromatographic procedures.