Screening of antifouling pesticides in sea water samples at low ppt levels by GC-MS and LC-MS

Studies of various analytical procedures for simultaneous determination of antifouling pesticides in sea water, based on SPE followed by GC-MS and LC-MS, have been made. The main characteristics of these compounds in GC-MS in both positive and negative modes and in LC-ES-MS were studied. Extraction of the compounds from filtered water was performed off-line with different SPE adsorbents using graphitized carbon (Envi-carb) and polymer cartridges (Isolute ENV+ and Oasis HLB) by passing 600 mL samples through them. Detection was carried out following selected analytical procedures (GC-MS in El and NCI modes) and LC-ES-MS (positive mode). Recoveries ranged from 80–95% except for dichlofluanid and Sea-nine 211 where they were 40 and 46%. In spite of this, the low coefficients of variation (<11%) obtained, were low enough to consider these recoveries adequately. Limits of detection were at low part-per-trillon levels in all cases. Finally, a six-month pilot study was carried out at various marinas in the South-East of Spain. Irgarol 1051 and diuron were revealed as the major antifouling agents in this area at concentrations up to 0.9 and 0.8 µg L−1 respectively.