Determination of organophosphorus, triazine and 2,6-dinitroaniline pesticides in aqueous samples via solid-phase microextraction (SPME) and gas chromatography with nitrogen-phosphorus detection

Abstract

Solid-phase microextraction (SPME) represents a very simple and rapid method for the extraction of organophosphorus, triazine and 2,6-dinitroaniline pesticides from aqueous samples without making use of any solvents. The same fiber can be used repeatedly. Moreover, a sample volume as small as 3 mL can be employed with no loss in sensitivity. 34 compounds have been extracted from aqueous samples by SPME using a 85 µm polyacrylate fiber. For organophosphorus pesticides, a 100 µm polydimethylsiloxane fiber has been used additionally for comparison. The fibers were directly introduced into the heated split/splitless injector of the gas chromatograph and determined using a nitrogen-phosphorus detector. The method was evaluated with respect to the limit of detection (LOD), linearity and precision. The limit of detection (LOD) depends on the compound and varies from 0.005-0.09 µg/L. The method is linear over at least three orders of magnitude with coefficients of correlation usually >0.999. For triazines and 2,6-dinitroanilines the coefficient of variation (precision) is <8 % while for organophosphorus compounds it may reach values up to 18 % (however, if the latter compounds are extracted using the polydimethylsiloxane phase considerably higher precision is achieved). The partitioning of the analyte between the aqueous phase and the polymeric phase depends on the hydrophobicity of the compound as expressed by the octanol/water partitioning coefficient (Pow). For triazines it was shown that there is a linear dependence of the logarithm of the analyte response on the log(Pow) i. e. the higher the hydrophobicity, the higher the affinity of the analytes to the polymeric phase of the fiber and the higher the response. Salt addition has a strong effect on the extraction efficiency. This effect increases with decreasing hydrophobicity (increasing polarity) of the compound. The triazines ametryn, atrazine, propazine, simazine and simetryn have been identified in a ground water well sample by SPME-GC/NPD

Use of SPME and Chemometrics in Method Development for Food and Environmental Analysis of Pesticide Residues

“…PDMS is the most commonly used fibre and have been employed for several applications such as determination of several main groups of pesticides in water at ppb levels [27][28][29], waste water [30][31][32], soil [33], food [33,34], and biological fluids [35,36,30]. There is a limited range of stationary phase and this gives rise to restriction for applicability [10].…”

Photodegradation and Flow-Injection Determination of Simetryn Herbicide by Luminol Chemiluminescence Detection

“…Methods for triazine determination in water include separation by HPLC [4][5][6] and GC 7,8 after solid-phase extraction (SPE), [9][10][11] capillary electrophoresis, 12 micellar electrokinetic capillary chromatography, 13 triazine multianalyte immunoassays, 14,15 CL/ ECL immunoassays, 16,17 ELISA, 18,19 ECL, 20 fluorometric methods with dansyl chloride 21 and photochemically-induced fluorometric method with o-phthalaldehyde-2-mercaptoethanol derivitazation. 22 These methods are sensitive and accurate; however, many of these involve expensive methods, and toxic solvents, are slow and require the development of extremely complex gradients for the separation.…”

An Improved Interface for Coupling Solid-Phase Microextraction (SPME) to High Performance Liquid Chromatography (HPLC) Applied to the Analysis of Explosives

“…SPME has been applied to the analysis of a wide range of volatile and semi-volatile compounds utilizing the effective combination of SPME and primarily GC analysis. Some of the varied applications have included the analysis of accelerants in fire debris [7], the environmental analysis of substituted benzene compounds [8] and pesticides [9] from aqueous solutions, the determination of caffeine in beverages [10] and compounds in flavor analysis [11].…”