Pesticides liquid chromatography

This publication provides several examples of the use of solid-phase extractions for separating analytes from their matrices. Some of the examples included are caffeine from coffee, polyaromatic hydrocarbons from water, parabens from cosmetics, chlorinated pesticides from water, and steroids from hydrocortisone creams. Extracted analytes maybe determined quantitatively by gas (GC) or liquid chromatography (LG). 

E. A. Hoogendoom and P. van Zoonen, Coupled-column reversed phase liquid chromatography as a versatile technique for the determination of polar pesticides in Environmental Analysis - Techniques, Applications and quality assurance, Barcelo D (Ed.), Vol. 13, Elsevier, Amsterdam, pp. 181-196 (1993). 

Figure 13.7 Selectivity effected by employing different step gradients in the coupled-column RPLC analysis of a surface water containing 0.40 p-g 1 bentazone, by using direct sample injection (2.00 ml). Clean-up volumes, (a), (c) and (d) 4.65 ml of M-1, and (b) 3.75 ml of M-1 transfer volumes, (a), (c) and (d), 0.50 ml of M-1, and (b), 0.40 ml of M-1. The displayed cliromatograms start after clean-up on the first column. Reprinted from Journal of Chromatography, A 644, E. A. Hogendoom et al, Coupled-column reversed-phase liquid chromatography-UV analyser for the determination of polar pesticides in water , pp. 307-314, copyright 1993, with permission from Elsevier Science.

N. Masque, R. M. Marce and R Bonnll, Comparison of different sorbents for on-line solid-phase exti action of pesticides and phenolic compounds from natural water followed by liquid chromatography , J. Chromatogr. 793 257-263 (1998). 

The development of bonded phases (Section 8.2) for liquid-liquid chromatography on silica-gel columns is of major importance. For example, the widely used C-18 type permits the separation of moderately polar mixtures and is used for the analysis of pharmaceuticals, drugs and pesticides. 

Figure 5.1 Pesticides included in the systematic investigations on APCI-MS signal response dependence on eluent flow rate the parameter IsTow represents the distribution coefficient of the pesticide between n-octanol and water. Reprinted from J. Chromatogr, A, 937, Asperger, A., Efer, 1., Koal, T. and Engewald, W., On the signal response of various pesticides in electrospray and atmospheric pressure chemical ionization depending on the flow rate of eluent applied in liquid chromatography-mass spectrometry , 65-72, Copyright (2001), with permission from Elsevier Science.

Figure 5.56 Structures of the three analytes pesticides used in an investigation of the matrix effects observed in LC-MS-MS. Reprinted from J. Chromatogr., A, 907, Choi, B. K., Hercnles, D. M. and Gnsev, A. I., Effect of liquid chromatography separation of complex matrices on liqnid chromatography-tandem mass spectrometry signal suppression , 337-342, Copyright (2001), with permission from Elsevier Science.

Barcelo D. 1988. Application of thermospray liquid chromatography/mass spectrometry for determination of organophosphoms pesticides and trialkyl and triaryl phosphates. Biomed Environ Mass Spectrom 17 363-369. 

Betowski LD, Jones TL. 1988. Analysis of organophosphoms pesticide samples by high-performance liquid chromatography/mass spectrometry and high-performance liquid chromatography/mass spectrometry/mass spectrometry. Environ Sci Technol 22 1430-1434. 

Distilled water, high-performance liquid chromatography grade Acetone, ethyl acetate, diethyl ether, acetonitrile, n-hexane, benzene, pesticide residue analysis grade... 

The need to understand the fate of pesticides in the environment has necessitated the development of analytical methods for the determination of residues in environmental media. Adoption of methods utilizing instrumentation such as gas chro-matography/mass spectrometry (GC/MS), liquid chromatography/mass spectrometry (LC/MS), liquid chromatography/tandem mass spectrometry (LC/MS/MS), or enzyme-linked immunosorbent assay (ELISA) has allowed the detection of minute amounts of pesticides and their degradation products in environmental samples. Sample preparation techniques such as solid-phase extraction (SPE), accelerated solvent extraction (ASE), or solid-phase microextraction (SPME) have also been important in the development of more reliable and sensitive analytical methods. 

The concept of SPME was first introduced by Belardi and Pawliszyn in 1989. A fiber (usually fused silica) which has been coated on the outside with a suitable polymer sorbent (e.g., polydimethylsiloxane) is dipped into the headspace above the sample or directly into the liquid sample. The pesticides are partitioned from the sample into the sorbent and an equilibrium between the gas or liquid and the sorbent is established. The analytes are thermally desorbed in a GC injector or liquid desorbed in a liquid chromatography (LC) injector. The autosampler has to be specially modified for SPME but otherwise the technique is simple to use, rapid, inexpensive and solvent free. Optimization of the procedure will involve the correct choice of phase, extraction time, ionic strength of the extraction step, temperature and the time and temperature of the desorption step. According to the chemical characteristics of the pesticides determined, the extraction efficiency is often influenced by the sample matrix and pH. 

E.M. Thurman, 1. Ferrer, and D. Barcelo, The ionization-continuum diagram a concept for selection of APCl and ESI conditions for HPLC/MS of pesticides , in 17th Montreux Symposium on Liquid Chromatography/Mass Spectrometry, Montreux, Switzerland, November 8-10, 2000 , p. 31 (2000). 

Schreuder, R. H., Martijn, A., Poppe, H., and Kraak, J. C., Determination of the composition of ethoxylated alkylamines in pesticide formulations by high-performance liquid chromatography using ion pair extraction detection, /. Chromatogr., 368, 339, 1986. 

Vandecasteele, K., Gaus, I., Debreuck, W., and Walraevens, K., Identification and Quantification of 77 Pesticides in Groundwater Using Solid Phase Coupled to Liquid-Liquid Microextraction and Reversed-Phase Liquid Chromatography, Anal. Chem. 72, 3093, 2000. 

Jongen, M.J.M, Engel, R., and Leenheers, L.H. (1991) High performance liquid chromatography method for the determination of occupational exposure to the pesticide abamectin, Am. Ind. Hygiene Assoc. ]., 52 433-437. 

Palma P, Kuster M, Alvarenga P, Palma VL, Fernandes RM, Soares AMVM, Lopez de Alda MJ, Barcelo D, Barbosa IR (2009) Risk assessment of representative and priority pesticides, in surface water of the Alqueva reservoir (South of Portugal) using on-line solid phase extraction-liquid chromatography-tandem mass spectrometry. Environ Int 35 545-551... 

Kuster M, de Alda MJL, Barata C, Raldua D, Barcelo D (2008) Analysis of 17 polar to semi-polar pesticides in the Ebro river delta during the main growing season of rice by automated on-line solid-phase extraction-liquid chromatography-tandem mass spectrometry. Talanta 75(2) 390-401... 

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