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B4-IL: TRACE ANALYSIS OF PESTICIDES AND PHARMACEUTICALS
IN WATER USING HPLC-MS/MS
Mila Laušević
Faculty of Technology and Metallurgy, University of Belgrade
Karnegijeva 4, 11000 Belgrade
Contamination of surface and ground water by wide range of pesticides and pharmaceuticals has been reported in the recent years in a number of studies worldwide. Their concentration found in surface and ground water is generally in the ng L-1 range. The consequences of continuous presence of low concentrations of pharmaceuticals and pesticides for the ecosystem are still not fully known. Their continual input into the environment may lead to a high, long-term concentration and promote unnoticed adverse effects on aquatic and terrestrial organisms. Effects can accumulate so slowly that changes remain undetected until they become irreversible. The presence of antibiotics is especially alarming, because it can lead to generation of resistant bacterial strains. It is quite clear that environmental risk assessment must be based on reliable data on actual concentrations of these substances in aquatic systems. Therefore, the monitoring of these substances is of a major importance.
Owing to the limited knowledge on concentrations, degradation and effects of the pharmaceuticals in water, they have not yet been included in water quality regulations. On the other hand, the levels of some pesticides, because of the high toxicity, have been strictly regulated. As pharmaceuticals and pesticides appear in water at a trace level, analytical methods for determination of all these analytes have to be both sensitive and specific. Analysis is further complicated by chemical and structural diversity of the analytes, so each type of analyte requires different sample preparation and pre-concentration method. Therefore, there is still need for new, reliable, multiresidual analytical methods, which will enable rapid, sensitive and selective determination and reliable confirmation of pharmaceuticals and pesticides in water at trace levels.
In our country the monitoring of pesticide contamination of surface and ground water has been mainly focused on organochlorine and triazine pesticides, while pharmacologically active substances have not yet been included in any environmental regulations. Other pesticide classes (such as organophosphates, neonicotinoids, carbamates, diacylhydrazines, benzimidazoles, and phenylureas) are commonly used, but are not yet included in the program of water quality monitoring.
The objective of our research is the development and optimization of multirezidual analytical methods for determination and reliable confirmation of pharmaceuticals and their metabolites as well as pesticides, including newly designed ones, in surface and ground water. Several procedures for efficient extraction and preconcentration of pharmaceuticals and pesticides from water, based on membrane extraction [1] and solid-phase extraction [2, 3] have been developed.
The instrumental method of choice for the analysis is high performance liquid chromatography (HPLC) coupled with mass spectrometry (MS). Mass spectrometry has the advantage over conventional detectors because it can provide information for unambiguous analyte identification even with poor HPLC separation. Tandem mass spectrometry (MS/MS) uses two stages of mass analysis - one to preselect an ion, and the second to analyze fragments induced by collision of an ion with an inert gas, such as helium. HPLC coupled with tandem mass spectrometry (HPLC–MS/MS) is capable of differentiation between analyte and matrix signal, as well as between the analytes that co-elute, therefore permitting quantification of pharmaceutical or pesticide traces even in very complex matrices.
The soft ionization techniques applied for HPLC–MS analyses is electrospray ionization (ESI). ESI is the ionization technique recommended for polar, ionized and high molecular weight compounds. Liquid-phase chemistry plays a key role in the ion formation in ESI, which is an interface that works well on any compound that is ionized in solution [4].
The most commonly used mass spectrometers that allow MS/MS experiments are triple quadrupole (TQ) and quadrupole ion trap (QIT). This is mainly due to their easier operating performance, their better robustness for routine analysis, and their relatively low cost compared to other MS instruments. The QIT is a small, low cost, easy to use, fast, sensitive, and versatile mass analyzer. Its unique feature is ability to perform multiple stages of MS. Also, it can simultaneously store positive and negative ions at once for extended periods of time. These characteristics make QIT an attractive option for detection of pharmaceuticals and pesticides. When performing MS/MS, QIT instruments are generally less sensitive than TQ analyzers, but they have the advantage of working in product-ion scan without losses in sensitivity and the possibility of performing multiple-stage fragmentation (MSn). Such advantages are important tools for unambiguous identification of trace compounds, such as pesticides or pharmaceuticals. The disadvantages of QIT are low resolution, interfering side-reactions (because all reactions occur in the same space), and a limited dynamic range.
We have used HPLC-MS/MS method with electrospray ionization and QIT mass spectrometer to develop procedure for multiresidual analyses of pesticides from the different chemical classes [1] as well as the multiresidual method for the analysis of pharmaceuticals from the different therapeutic classes [5]. Selected analytes were the most frequently used pesticides and pharmaceuticals in our region. The developed procedures were applied for the analysis of surface and ground water samples collected in Serbia and the presence of both pharmaceuticals and pesticides was confirmed.
References
- T. Trtić-Petrović, J. Đorđević, N. Dujаković, K. Kumrić, T. Vаsiljević, M. Lаušević, Determination of selected pesticides in environmental water by membrane based liquid-liquid extraction and liquid chromatography-tandem mass spectrometry, Analytical and Bioanalytical Chemistry, doi: 10.1007/s00216-010-3725-5.
- S. Grujic, T. Vasiljevic, M. Radisic, M. Lausevic, Determination of pesticides by matrix solid-phase dispersion and liquid chromatography–tandem mass spectrometry, In Handbook of Pesticides: Methods of Pesticide Residues Analysis, ed. LML Nollet, H.S. Rathore, CRC Press, Taylor & Francis Group, Boca Raton, FL, USA, 2010, 141-164.
- M. Radišić, S. Grujić, T. Vasiljević, M. Laušević, Determination of selected pesticides in fruit juices by matrix solid-phase dispersion and liquid chromatography-tandem mass spectrometry, Food Chemistry, 2009, 113, 712-719.
- S. Grujić, T. Vasiljević, M. Lausević, T. Ast, Study on formation of amoxicillin adduct with methanol using electrospray-ion trap-tandem mass spectrometry, Rapid Commun. Mass Spectrom., 2008, 22, 67-74.
- S. Grujić, T. Vasiljević, M. Laušević, Determination of multiple pharmaceutical classes in surface and ground waters by liquid chromatography-ion trap-tandem mass spectrometry, Journal of Chromatography A, 2009, 1216, 4989-5000.
Prof. Dr. Mila Laušević is a Professor at the Faculty of Technology and Metallurgy, University of Belgrade, Department of Analytical Chemistry and an associate member of the Department of Environmental Engineering.
Education: B.Sc. (1975), M.Sc. (1980) and Ph.D. (1984) from the Faculty of Technology and Metallurgy, University of Belgrade.
Research and teaching visits:
1978-1979 postgraduate student at the Jozef Stefan Institute Ljubljana
1980-1983 research assistant at the University College Swansea, Swansea, U.K.
1994-1996 visiting professor at the Trent University, Peterborough, Canada, teaching Instrumental analysis at undergraduate and graduate level, research in application of GC-MS/MS in environmental analysis.
Areas of Expertise: Mass spectrometry, Instrumental analysis, Environmental analysis
Teaching activities at TMF: Instrumental analysis and environmental analysis undergraduate and graduate level.
Research activities at TMF: Head of the Mass Spectrometry Laboratory at TMF, organizing research in application of mass spectrometry in environmental analysis.
Publications: Author or coauthor of more than 60 publications in scientific literature, cited by other authors over 700 times
