Organochlorine Pesticides by LC-MS G. Famiglini, P. Palma, E. Pierini, H. Trufelli, and A. Cappiello* Istituto di Scienze Chimiche “F. Bruner”, Universita ` di Urbino “Carlo Bo”, Piazza Rinascimento 6, 61029 Urbino, Italy Contamination of water resources by organochlorine pesticides (OCPs) continues to receive widespread atten- tion because of the increasing concern regarding their high persistence and bioaccumulation. These organic pollutants are not amenable by liquid chromatography (LC) coupled to atmospheric pressure ionization-mass spectrometry, which represents the method of choice for the characterization of pesticide residues in water. Gas chromatography-mass spectrometry provides excellent response for OCPs, but it falls short when complex, multiresidue analyses are required. As recently demon- strated, an efficient EI-based LC-MS interface can gener- ate very good spectra for an extremely wide range of small-medium molecular weight molecules of different polarity and can represent a valid tool in solving the analytical challenge of analyzing OCPs by LC-MS. Based on this assumption, we present a new approach for the determination of 12 OCPs in water samples. The method requires a solid-phase extraction preconcentration step followed by nanoscale liquid chromatography coupled to a direct-electron ionization direct interface (Direct-EI). Direct-EI is a miniaturized interface for efficiently coupling a liquid chromatograph with an EI mass spectrometer. The capability to acquire high-quality EI spectra in a wide range of concentrations, and to operate in selected ion monitoring mode during analyses, allowed a precise quantification of the OCPs. Without sample injection enrichment, limits of detection of the method span from 0.044 to 0.33 μg/L, corresponding to an instrumental detection limit of 120-850 pg. In addition, a careful evaluation of the matrix effect showed that the response of the Direct-EI interface was never affected by sample interferences. From our knowledge, the proposed method represents the first application of LC-MS in the analysis of organochlorine pesticides. Organochlorine pesticides (OCPs) have been extensively used throughout the world. They are very persistent in the environment due to their high chemical stability and their strong tendency to sorb to organic material in soil and sediments. 1,2 They can cause acute and chronic effects, including cancer, neurological damages, and birth defects, 3-5 and many of them act as endocrine disrup- tors. 6 Most developed countries have banned their use since the late 1970s, in favor of more modern and readily degradable pesticide formulations. However, OCPs are still extensively used in developing regions because of their low cost and their effectiveness. They enter the food chain through contaminated water, fish, and shellfish. 7-15 OCPs show low polarity, high thermal stability, and volatility. As a consequence, the analytical protocols proposed for their determination are traditionally based on gas chromatography (GC) mainly coupled to detection techniques such as electron capture detection and mass spectrometry (MS). 16-19 However, this represents a significant constrain in multiresidue analysis, when high polar, poorly volatile compounds are present as well. Therefore, liquid chromatography-mass spectrometry (LC-MS) represents the method of choice for pesticide multiresidue applications. 20,21 In a recent review, 22 the applicability and the sensitivity obtained by GC-EI-MS and LC- * To whom correspondence should be addressed. Tel: +390722303344. Fax: +390722303311. E-mail: achille.cappiello@uniurb.it. (1) Fiedler, H.; Lau, C. Ecotoxicology 1998, 317-370. (2) Jones, K. C.; De Voogt, P. Environ. Pollut. 1999, 100, 209-221. (3) Ritchie, J. M.; Vial, S. L.; Fuortes, L. J.; Guo, H.; Reedy, V. E.; Smith, E. M. J. Occup. Environ. Med. 2003, 45, 692-702. (4) Fenster, L.; Eskenazi, B.; Andreson, M.; Bradman, A.; Harley, K.; Hernandez, H.; Hubbard, A.; Barr, D. B. Environ. Health Perspect. 2006, 114, 597- 602. (5) Kaushik, P.; Kaushik, G. J. Hazard. Mater. 2007, 143, 102-111. (6) Gore, A. C. Mol. Cell. Endocrinol. 2002, 192, 157-170. (7) Nowell, L. H.; Capel, P. D; Dileanis, P. D. Pesticides in Stream Sediment and Aquatic Biota-Distribution, Trends, and Governing Factor; CRC Press: Boca Raton, FL, 1999. (8) Carvalho, F. P.; Gonzalez-Farias, F.; Villeneuve, J. P.; Cattini, C.; Hernandez- Garza, M.; Mee, L. D.; Flower, S. W. Environ. Technol. 2002, 23, 1257- 1270. (9) Ming-Lone, L.; Shin-Cheng, Y.; Yong-Chien, L.; Chien-Min, C. Hum. Ecol. Risk Assess. 2006, 12, 390-401. (10) Environamental Protection Agency (EPA). Assessing human health risk from chemically contaminated fish and shellfish: a guidance manual/EPA-503/ 8-89-002, Appendix F; U.S. EPA: Cincinnati, OH, 1998. (11) MacIntosh, D. L.; Spengler, J. D.; Ozkaynak, H.; Tsai, L.; Ryan, P. B. Environ. Health Perspect. 1996, 104, 202-209. (12) Jiang, Q. T.; Lee, T. K. M.; Chen, K.; Wong, H. L.; Zheng, J. S.; Giesy, J. P.; Lo, K. K. W.; Yamashita, N.; Lam, P. K. S. Environ. Pollut. 2005, 136, 155- 165. (13) Scheyer, A.; Graeff, C.; Morville, S.; Mirabel, P.; Millet, M. Chemosphere 2005, 58, 1517-1524. (14) Connor, M. S.; Davis, J. A.; Leatherbarrow, J.; Greenfield, B. K.; Gunther, A.; Hardin, D.; Mumley, T.; Werme, C. Environ. Res. 2007, 105, 87-100. (15) Ferrante, M. C.; Cirillo, T.; Naso, B; Clausi, M. T.; Lucisano, A.; Cocchieri, R. A. J. Food Prot. 2007, 70, 706-715. (16) Mangani, F.; Maione, M.; Palma, P. In Handbook of Water Analysis; Nollet, L. M. L., Ed.; Marcel Dekker: New York, 2000; pp 517-536. (17) Barriada-Pereira, M.; Gonza ´ lez-Castro, M. J.; Muniategui-Lorenzo, S.; Lo ´ pez- Mahı ´a, P.; Prada-Rodrı ´guez, D.; Ferna ´ ndez-Ferna ´ndez, E. Chemosphere 2005, 1571-1578. (18) Yenisoy-Karakas ¸ , S. Anal. Chim. Acta 2006, 571, 298-307. (19) Guardia-Rubio, M.; Ruiz, Medina, A.; Pascual, Reguera, M. I.; Ferna ´ndez, de Co ´ rdova, M. L. Microchem. J. 2007, 85, 257-264. (20) Reemtsma, T. J. Chromatogr., A 2003, 1000, 477-501. (21) Kuster, M.; Lo ´ pez, de Alda, M.; Barcelo ´ , D. Mass Spectrom. Rev. 2006, 25, 900-916. (22) Alder, L.; Greulich, K.; Kempe, G.; Vieth, B. Mass Spectrom. Rev. 2006, 25, 838-865. Anal. Chem. 2008, 80, 3445-3449 10.1021/ac8000435 CCC: $40.75 © 2008 American Chemical Society Analytical Chemistry, Vol. 80, No. 9, May 1, 2008 3445 Published on Web 03/18/2008