Determination of Organophosphorus Pesticides in Juice and Water by Modified Continuous Sample Drop Flow Microextraction Combined with Gas Chromatography–Mass Spectrometry (original) (raw)
Related papers
2004
Gas chromatography-mass spectrometry (GC-MS) has been widely applied for pesticide monitoring because of its high sensitivity and specificity and for the potential of multi-residue and multi-class analysis. An analytical procedure was developed for the determination of pesticide multi-residues in water samples combining solid-phase micro-extraction (SPME) and gas chromatography-ion trap mass spectrometry. For SPME extraction a poly(dimethylsiloxane)-divinylbenzene coated fibre was selected whereas the mass spectrometer was operated under full scan, selected ion storage (SIS), SIS (SIM) and MS-MS and the figures of merit compared. Quantitative and qualitative (confirmatory) capabilities of each operation mode are discussed. Using MS-MS, precision was typically below 10% and limits of detection (LODs) were improved by 1.3 to 20 times (to low-or sub-ppt levels) compared to SIS, with the advantage of maintaining identification capabilities. The combination of selective extraction by SPME and highly selective determination by GC-MS-MS made possible ultra-selective and essentially error-free determination of pesticides in complex environmental samples. This aspect will be highlighted in the paper.
Food Chemistry, 2020
A simple, sensitive and environmentally-friendly method for determining organophosphorus and pyrethroid pesticides in vegetables was developed to better evaluate the risk of consuming them. The pesticides in vegetables were extracted, purified and concentrated by using the QuEChERS (quick, easy, cheap, effective, rugged and safe method) combined DLLME-SFO (dispersive liquid-liquid microextraction based on solidification of floating organic droplet) techniques. The key parameters were optimized through orthogonal array experimental design and statistical analysis. The linearity of the calibration curves was satisfied in matrix-matched standard solution with R 2 ≥ 0.99. The limits of detection and limits of quantification were 0.3-1.5 and 0.9-4.7 μg/kg, respectively. The average recoveries of pesticides were 61.6-119.4% with relative standard deviations < 16.1%. Furthermore, the method was applied successfully to analyse the pesticides in 15 pairs of organic and conventional vegetables. These results reflect the efficiency, reliability and robustness of the developed method.
Microchimica Acta, 2012
We have developed a new method for single-drop microextraction (SDME) for the preconcentration of organochlorine pesticides (OCP) from complex matrices. It is based on the use of a silicone ring at the tip of the syringe. A 5 μL drop of n-hexane is applied to an aqueous extract containing the OCP and found to be adequate to preconcentrate the OCPs prior to analysis by GC in combination with tandem mass spectrometry. Fourteen OCP were determined using this technique in combination with programmable temperature vaporization. It is shown to have many advantages over traditional split/splitless injection. The effects of kind of organic solvent, exposure time, agitation and organic drop volume were optimized. Relative recoveries range from 59 to 117 %, with repeatabilities of <15 % (coefficient of variation) were achieved. The limits of detection range from 0.002 to 0.150 μg kg −1. The method was applied to the preconcentration of OCPs in fresh strawberry, strawberry jam, and soil.
Single-drop microextraction for the analysis of organophosphorous insecticides in water
Analytica Chimica Acta, 2004
A new method used for the extraction of 10 organophosphorous insecticides from water samples coupling single-drop microextraction with gas chromatography-mass spectrometry is presented here. Parameters, such as organic solvent, exposure time, agitation, organic drop volume and salt concentration were controlled and optimised. Overall, extraction was achieved by suspending a 1.5 l toluene drop to the tip of a microsyringe immersed in a 5 ml donor aqueous solution containing 2.5% NaCl (w/v) and stirred at 800 rpm. The developed protocol was found to yield a linear calibration curve in the concentration range from 0.5 to 100 g l −1 for all target analytes. Under selected ion monitoring mode, the limits of detection were found to be in the range between 0.010 and 0.073 g l −1 . The intra-day and inter-day repeatability of the method varied between 8.6 and 16, and 11 and 19%, respectively. The relative recoveries from several types of natural water samples were evaluated and the effect of dissolved organic matter (humic acids) was investigated. Finally, the performance of the proposed method was compared to that of solid-phase microextraction. Overall, single-drop microextraction proved to be a fast and simple tool for the preconcentration of organophosphorous insecticides from water samples.
Journal of Chromatography A, 1998
Solid-phase microextraction (SPME) is a relatively new technique that appears as a convenient and efficient extraction method in contrast with more complex techniques used for pesticide residue analysis based on liquid-liquid and solid-phase extraction. This extraction procedure involves the absorption of analytes into a polymeric film coated onto a fine silica fiber directly dipped in the aqueous sample. An SPME procedure for the determination of 12 organophosphorus pesticides in clean environmental water samples at low ng / ml concentration level has been developed by optimising variables involved in extraction and desorption. The absorption equilibrium has been estimated by mathematical treatment of the process using an expression that describes experimental absorption time profiles. The method was evaluated according to the reproducibility, linearity range and limits of detection using two different fiber coatings: 100 mm polydimethylsiloxane and 85 mm polyacrylate. The limits of detection obtained using nitrogen-phosphorus detection ranged between 0.01 and 0.2 ng / ml with relative standard deviations lower than 15% at the 1 ng / ml level. The method showed good linearity between 0.1 and 10 ng / ml with regression coefficients ranging between 0.97 and 0.999. Determination of organophosphorus pesticides in water samples in concentration below 0.1 ng / ml can be easily carried out with this fast, economic and solvent-free SPME procedure.
Analyst, 2000
A simple, rapid and sensitive multiresidue method has been developed for the determination of ten organophosphorus and organochlorine pesticides, commonly used in crop protection. The analysis uses a miniaturised extraction with ethyl acetate followed by large volume injection (10 mL) GC-EI-MS analysis in SIM (selective ion monitoring) mode. Sensitivity and selectivity of the method were acceptable with limits of detection (LODs) lower than 0.01 mg kg 21 , except for endosulfan a and b (0.05 mg kg 21). Average recoveries of between 63-99% were obtained and good linearity was observed in the range from 0.01 to 1.00 mg kg 21. Repeatability and reproducibility studies yielded relative standard deviations lower than 20% in all the cases. The method was applied to the analysis of 110 tomato, pepper and cucumber samples, as part of the monitoring programme of the Association of Producers and Exporters of Fruits and Vegetables of Almería.
Journal of High Resolution Chromatography, 1997
This paper describes the extraction of 49 organophosphorus pesticides (OPPs) from water samples using solid-phase microextraction (SPME). Three fibers, including a 15-km XAD-coated fiber, a 85ym polyacrylate-coated fiber, and a 30-km polydimethylsiloxane-coated fiber (PDMS), were evaluated here. The effects of stirring and the addition of NaCl to the sample were examined for the polyacrylate-coated fiber. The precision of the technique was examined for all three fibers and the extraction kinetics were investigated using the XAD-and polyacrylate-coated fibers. With some exceptions, the XAD-and polyacrylate-coated fibers performed better than the PDMS-coated fiber. The superiority of the XAD-and polyacrylate-coated fibers over the PDMS-coated fiber can be attributed to the aromatic functionalities of the XAD and the polar functionalities in the polyacrylate. The relatively high percent RSDs indicate that the SPME technique needs to be further refined before it can be used for anything other than screening. A more effective form of agitation than mechanical stirring may be necessary to reduce variability and achieve a faster equilibrium between the sample and the SPME fiber. I) New address: Roche BioScience, Palo Alto, California J. High Resol. Chromatogr.