Organophosphorus Pesticides In Samples Research Articles

MONITORING OF ORGANOPHOSPHOROUS PESTICIDE RESDUES IN SAMPLES OF BANANA, PAPAYA, AND BELL PEPPER

The objective of this study was to monitor 11 organophosphorus pesticides in samples of papaya, bell pepper, and banana, commercialized in the metropolitan area of Vitoria (ES, Brazil). The pesticides were determined by an optimized and validated method using high performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS). All three samples exhibited a matrix effect for most of the pesticides, mainly with signal suppression, and therefore the calibration curves were produced in matrices. Linearity revealed coefficients of determination (r2) greater than 0.9895 for all pesticides and recovery results ranged from between 76% and 118% with standard deviation no greater than 16%. Precision showed relative standard deviation values lower than 19% and HorRat values lower than 0.7, considering all pesticides. Limits of quantification were less than 0.01 mg/kg for all pesticides. Regarding analysis of the samples (50 of each), none of the pesticides exceeded the maximum residue limit determined by Brazilian legislation.

Study on the effect of chain-length compatibility of mixed anionic–cationic surfactants on the cloud-point extraction of selected organophosphorus pesticides

The chain-length compatibility of mixed anionic-cationic surfactants was investigated for the extraction of organophosphorus pesticides (OPPs). Cationic surfactants with different chain lengths (n = 12 and 16) were mixed with sodium dodecyl sulfate (SDS; n = 12) for the mixed anionic-cationic surfactants-based extraction. Six OPPs were studied including azinphos-methyl, parathion-methyl, fenitrothion, diazinon, chlorpyrifos, and prothiophos. Reversed-phase high-performance liquid chromatography was used for the determination of the studied OPPs. The extraction was performed using mixtures of SDS and cationic surfactants including dodecyltrimethyl ammonium bromide or dodecyltrimethylammonium bromide (DTAB; n = 12) and cetyltrimethyl ammonium bromide or cetyltrimethyl ammonium bromide (CTAB; n = 16). The parameters affecting the extraction efficiencies of two extraction systems were studied and discussed. The optimum condition for SDS-DTAB was 15 mmol L(-1) SDS and 1 mmol L(-1) DTAB in the presence of 15% (w/v) sodium chloride (NaCl). Meanwhile, the condition for SDS-CTAB was 10 mmol L(-1) SDS and 1.0 mmol L(-1) CTAB with 10% (w/v) NaCl. Under the optimum conditions, the extraction efficiency of SDS-DTAB (66-85%) was slightly higher than that of SDS-CTAB (61-82%). In addition, the SDS-DTAB system also gave greater enrichment factor than SDS-CTAB for all the studied OPPs. This result may be due to the compatibility of chain length between SDS and DTAB. The extraction using SDS-DTAB was successfully applied to determine OPPs in fruit samples (i.e., pomelo, apple, and pineapple). No contamination by the studied OPPs in samples was observed. Good accuracy with recoveries ranging from 77 to 105% was obtained. Low limits of detection were in the range of 0.003-0.01 mg kg(-1) which are below the MRLs established by EU-MRLs for the OPPs residues in fruit samples.

Determination of 49 Organophosphorus Pesticide Residues and Their Metabolites in Fish, Egg, and Milk by Dual Gas Chromatography–Dual Pulse Flame Photometric Detection with Gel Permeation Chromatography Cleanup

A new method for the quantitative determination of 49 kinds of organophosphorus pesticide residues and their metabolites in fish, egg, and milk by dual gas chromatography-dual pulse flame photometric detection was developed. Homogenized samples were extracted with acetone and methylene chloride (1 + 1, v/v), and then the extracts were cleaned up by gel permeation chromatography (GPC). The response of each organophosphorus pesticide showed a good linearity with its concentration; the linearity correlation was not less than 0.99. The detection limits (S/N = 3) of pesticides were in the range of 0.001-0.025 mg kg⁻¹. The recovery experiments were performed by blank sample spiked at low, medium, and high fortification levels. The recoveries for fish, egg, and milk were 50.9-142.2, 53.3-137.2, and 50.3-139.4% with relative standard deviations (RSD, n = 6) of 2.3-24.9, 4.3-26.7, and 2.8-32.2%, respectively. The method was applied to detect organophosphorus pesticides in samples collected from the market, and satisfactory results were obtained. This quantitative method was highly sensitive and exact and could be applied to the accurate determination of organophosphorus contaminants in fish, egg, and milk.

Green extraction using catanionic surfactants of trimethyltetradecyl ammonium bromide–sodium dodecyl sulfate for preconcentration of organophosphorus pesticides in fruit samples

An extraction method using mixed catanionic surfactants of trimethyltetradecyl ammonium bromide (TTAB) and sodium dodecyl sulfate (SDS) was developed for preconcentration of organophosphorus pesticides (OPPs) before analysis by high performance liquid chromatography (HPLC). The studied OPPs are azinphos-methyl, parathion-methyl, fenitrothion, diazinon, chlorpyrifos, and prothiophos. The optimum extraction condition was 10 mmol L−1 SDS and 0.5 mmol L−1 TTAB in the presence of 10% (w/v) NaCl and equilibration at room temperature. The concentrated target pesticides were subsequently analyzed using a Symmetry C8 column, gradient elution of acetonitrile and water, at a flow rate of 0.8 mL min−1, and detection at 210 nm. Enrichment factors were found in the range of 16–30. The limits of detection of the studied OPPs were 0.001–0.01 mg L−1 which are below the maximum residue limits (MRLs) established by the European Union. Good repeatability (n = 5) and reproducibility (n = 15) were obtained with the relative standard deviation (RSD) below 2% for retention time and below 9% for peak area, respectively. The validation of the proposed method for fruit sample analyses was carried out by matrix matched calibration. A modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) method was used for sample preparation before extraction and preconcentration. Recovery of the fortified samples at three levels (0.25, 1.50 and 2.50 mg kg−1) was higher than 80.9% (on average) for all studied fruit samples (pomelo and pineapple). No detectable residues of OPPs in samples were found.

Determination of organophosphorous pesticides in water using in-syringe ultrasound-assisted emulsification and gas chromatography with electron-capture detection

An in-syringe ultrasound-assisted emulsification microextraction (USAEME) was developed for the extraction of organophosphorus pesticides (OPPs) from water samples. The OPPs subsequently analyzed gas chromatography (GC) using a microelectron capture detector (μECD). Ultrasound radiation was applied to accelerate the emulsification of μL-level low-density organic solvent in aqueous solutions to enhance the microextraction efficiency of OPPs in the sample preparation for GC-μECD. Parameters affecting the efficiency of USAEME, such as the extraction solvent, solvent volume, pH, salt-addition, and extraction time were thoroughly investigated. Based on experimental results, OPPs were extracted from a 5 mL aqueous sample by the addition of 20 μL toluene as the extraction solvent, followed by ultrasonication for 30 s, and then centrifugation for 3 min at 3200 rpm, offered the best extraction efficiency. Detections were linear in the concentration of 0.01–1 μg/L with detection limits between 1 ng/L and 2 ng/L for OPPs. Enrichment factors ranged from 330 to 699. Three spiked aqueous samples were analyzed, and recovery ranged from 90.1% to 104.7% for farm-field water, and 90.1% to 101.8% for industrial wastewater. The proposed method provides a simple, rapid, sensitive, inexpensive, and eco-friendly process for determining OPPs in water samples.

Application of programmable temperature vaporisation injection with resistive heating‐gas chromatography flame photometric detection for the determination of organophosphorus pesticides

The combination of a programmable temperature vaporisation (PTV) injector with resistive heating GC (RH-GC), a form of fast GC, has been applied to the analysis of organophosphorus (OP) pesticides. The PTV injector was optimised in the 'at-once' solvent vent mode for the injection of ethyl acetate (10-40 microL) or ACN (10 microL). The short RH-GC column (5 m x 0.25 mm ID) with fast temperature ramps (up to 153 degrees C/ min) allowed the separation of a total of 20 OP pesticides in less than 6 min. Average recoveries between 67 and 119% were obtained for pesticides spiked at 0.01 mg/kg into apple and pear matrix. Extraction of orange juice with ACN provided higher recoveries (92-104%) for methamidophos, acephate and omethoate compared to ethyl acetate (62-73%). Results for analysis of OP pesticides in samples containing incurred residues were in good agreement with those obtained using GC-MS. The overall method was rapid, allowing 20 samples to be analysed in 4 h.

Comparison of methods for the determination of residues of organophosphorus pesticides in samples having incurred residues

Comparison of methods for the determination of residues of organophosphorus pesticides in samples having incurred residues