A gas chromatographic determination of residues of eleven insecticides and two metabolites on olive tree leaves

A gas chromatographic (GC) method was developed and statistically validated for the simultaneous determination of residues of pyrethroid, endosulfan, and organophosphorus insecticides and some of their metabolites on olive tree leaves. Pesticide residues were extracted by static extraction with acetone-dichloromethane. After evaporation of the extract to dryness and redissolution in acetone, the organophosphorus insecticides were determined by GC with nitrogen-phosphorus detection. Another portion of the extract, after solvent change to acetonitrile, was cleaned up on an Alumina-N cartridge and analyzed for insecticides sensitive to electron-capture detection (ECD), i.e., pyrethroids and endosulfan and its metabolite. Recoveries of the organophosphorus insecticides ranged from 80.7 to 93.3% with relative standard deviations (RSDs) of < or = 7.2%; recoveries of the ECD-sensitive insecticides ranged from 71.6 to 89.5% with RSDs of < or = 11.6%. The method was used to analyze 26 samples of olive tree leaves from organic olive groves all over Greece, and the results confirmed the viability of the method for routine analysis. Residues of fenthion and fenthion sulfoxide were found in one and 3 samples, respectively, and their identities were confirmed by GC with mass spectrometry.     

Cleanup of Samples for High Performance Chromatography and Instrumental Analysis

Abstract

Cleanup methods have been developed which allow utilization of modern chromatographic techniques and instrumental readouts. A cellulose cleanup for organo-phosphorus pesticides and carbamates has already been reported. A particulate carbon column has been described for Rumensin. These columns maybe combined to improve the cleanup for organophosphorus and carbamate pesticides. This same column cleanup maybe used for Ochratoxin. Powder charcoal maybe used for the mycotoxins aflatoxin, and zearalencne. It maybe used for T-2 toxin and trichothecenes with some loss (50-75% recovery).

The thin layer plates themselves provide a background reference for spectroscopy. This background maybe removed by “annealing” the plates at 400°C for 2 hours.

Sweepco distillation maybe used to cleanup biological samples so that carbamates and organophosphorus pesticides maybe analyzed by thin layer chromatography. Trichothecenes mycotoxins maybe cleanuped with about 40% loss.     

Electrochemical Synthesis of Organophosphorus Compounds on the Base of Elemental Phosphorus

Abstract

The straight synthesis of organophosphorus compounds on the base of white phosphorus may solve a lot of problems concerning with simplification technology proceeding as a whole. At present time we are investigating procedures for the electrochemical generation of organophosphorus compounds directly white phosphorus The ability to carry out this type of procedure in single step will have considerable environmental benefits. Thus procedure affording trialkylphosphates in a yield more than 90% and purity up to 98% for row material in undivided cell has been elaborated.     

Reliable System for the Analysis of Riboflavin in Foods by High Performance Liquid Chromatography and UV Detection

Abstract

A high performance liquid chromatographic (HPLC) method has been developed to determine riboflavin in food samples. A reverse phase C₁₈ column with ultraviolet detection was employed. Sample preparation included acid and enzimatic hydrolysis, followed by purification on Florisil and Sep-Pak cartridges. Recoveries of 98% were obtained. A detection limit of 0.4 ng/injection has been achieved.     

Photodegradation of Selected Organophosphorus Insecticides Under Sunlight in Different Natural Waters and Soils

In this work photodegradation of four organophosphorus insecticides (ethyl-parathion, methyl-parathion, fenitrothion, fenthion) in different natural waters and soils was studied under sunlight. The origin of the waters was from the region of Ioannina (underground, lake, and river water) and from Preveza (sea water) in Northern-West Greece. The soils used had different percentages of organic matter (0.9-3.5%) and their characterization were SCL, CL, and SL respectively. The photodegradation kinetics of these insecticides were followed by GC-FTD. The identification of the photodegradation by-products was made by using GC-MS. The half-lives of the organophosphorus insecticides vary from 0.4 to 35.4 days in natural waters and from 3.4 to 21.3 days in soils. The humic substances and the other components of these environmental matrices seem to influence the degradation kinetics. The use of GC-MS allowed the identification of some important photodegradation by-products such as: fenthion sulfone, fenthion sulfoxide, fenoxon, 4-methylthio-3,5-dimethyl phenol, O , O , O -triethyl phosphorothioate, paraoxon, 4-nitrophenol, aminoparathion.     

Multi-residue determination of 41 insecticides in garlic by gas chromatography and ion trap mass spectrometry using the selective ion storage technique

A method is described for determining 41 insecticide residues in garlic (Allium sativum L.), including organophosphorus, organochlorine, carbamate, and synthetic pyrethroid insecticides. These insecticides were extracted from samples with acetone and dichloromethane, and co-extractives removed using a charcoal/Celite/alumina column. Analysis was performed by gas chromatography with ion trap mass spectrometry in selective ion storage (SIS) mode. Retention times and specific ions (m/z values) were used to confirm insecticides. Recoveries for most insecticides (blank samples spiked at 0.05, 0.2 and 1 microg mL(-1) levels) ranged from 70% to 110%, the coefficient of variation (CV) of the method was <20% for every case, and the limit of detection (LOD), defined in terms of 3 times baseline noise, varied between 0.01 and 0.16 mg kg(-1), depending on the compound.     

Determination of insecticides in honey by matrix solid-phase dispersion and gas chromatography with nitrogen-phosphorus detection and mass spectrometric confirmation

A multiresidue method was developed for the determination of 12 organophosphorus insecticides (diazinon, parathion methyl, fenitrothion, pirimiphosmethyl, malathion, fenthion, chlorpyrifos, quinalphos, methidathion, ethion, azinphosmethyl, coumaphos), one carbamate (pirimicarb), and one amidine (amitraz) in unifloral and multifloral honeys. The analytical procedure was based on the matrix solid-phase dispersion of honey on a mixture of Florisil and anhydrous sodium sulfate in small glass columns and subsequent extraction with a low volume of hexane-ethyl acetate (90 + 10, v/v), assisted by sonication. The insecticide residues were determined by capillary chromatography with nitrogen-phosphorus detection and confirmed by mass spectrometry. Average recoveries at the 0.05-0.5 microg/g levels were >80% for organophosphorus insecticides and about 60% for the other insecticides, pirimicarb and amitraz, with relative standard deviations <10%. The detection limit for the different insecticides ranged between 6 and 15 microg/kg. The main advantages of the proposed method are that extraction and cleanup are performed in a single step with a low volume of organic solvent. The method is simple, rapid, and less laborious than conventional methods. Several Spanish honeys were analyzed with the proposed method and no residues of the studied insecticides were found.     

Optimization of headspace solid-phase microextraction conditions for the determination of organophosphorus insecticides in natural waters

Headspace solid-phase microextraction (HS-SPME) has been developed for the analysis of seven organophosphorus insecticides, i.e. diazinon, fenitrothion, fenthion, ethyl parathion, methyl bromophos, ethyl bromophos and ethion in natural waters. Their determination was carried out using gas chromatography with flame thermionic and mass spectrometric detection. To perform the HS-SPME, two types of fibre have been assayed and compared: polyacrylate (PA 85 microm), and polydimethylsiloxane (PDMS 100 microm). The main parameters affecting the HS-SPME process such as temperature, salt additives, memory effect, stirring rate and adsorption-time profile were studied. The method was developed using spiked natural waters such as ground, sea, river and lake water in a concentration range of 0.05-1 microg/l. The HS-SPME conditions were optimized in order to obtain the maximum sensitivity. Detection limits varied from 0.01 to 0.04 microg/l and relative standard deviations (RSD <17%) were obtained showing that the precision of the method is reliable. The method showed also good linearity for the tested concentration range with regression coefficients ranging between 0.985 and 0.999. Recoveries were in relatively high levels for all the analytes and ranged from 80 to 120%. Water samples collected from different stations along the flow of Kalamas river (NW Greece) were analyzed using the optimized conditions in order to evaluate the potential of the proposed method to the trace-level screening determination of organophosphorus insecticides. The analysis with HS-SPME has less background interference and the advantage of its non-destructive nature reveal the possibility of the repetitive use of the SPME fibre.     

QSAR in Reactions of Organophosphorus Inhibitors with Acetylcholinesterase

Abstract

Structure-activity relationships in inhibition of acetylcholinesterase by organophosphorus compounds (YO)(Z)P(O)SX have been analyzed using the equation log k_i = C + ρσ + ?π with Taft σ* for substituent elehtronegativity and Hansch Π for hydrophobicity. The obtained relationships have been used for optimizing the structures of organophosphorus inhibitors for their maximum anticholinesterase activity.     

Determination of the residues of eleven organophosphorus insecticides in Job's-tears by gas chromatography with a nitrogen-phosphorus detector

A simplified method for determining 11 organophosphorus insecticides (dichlorvos, methamidophos, acephate, diazinon, dimethoate, chlorpyrifos, malathion, parathion, quinalphos, methidathion, and ethion) in the Chinese herbal medicine Job's-tears is described. Standards were fortified into Job's-tears (5 g) at 4 levels. The organophosphorus insecticides were extracted with dichloromethane and cleaned up with a mixture of Celite 545-activated carbon (4 + 1). The extracts were analyzed by gas chromatography using a nitrogen-phosphorus detector. Analysis of fortified Job's-tears shows average recoveries ranged from 73.90-98.70%, 86.31-93.15%, 84.92-96.22%, and 83.29-104.23% at 0.05, 0.1, 0.5, and 1.0 mg/kg levels, respectively. The minimum detectable amount ranged from 1.0 x 10(-10) to 5.0 x 10(-10) g, and the limit of quantitation for the method was 0.05 mg/kg. The method is rapid, simple, sensitive, reproducible, and applicable to the determination of these 11 organophosphorus insecticides in Job's-tears.     

A New Organophosphorus Insecticides Removal Process Using Fly ASH

Abstract

Fly ash and soil mixtures with a range of fly ash content from 1 to 100% were used to study adsorption and desorption of four organophosphorus insecticides, ethyl parathion, methyl parathion, fenitrothion and fenthion, in batch experiments. The object of the study was to develop a treatment process using fly ash as sorbent material to isolate/immobilize organic contaminants from aqueous solutions. The adsorption isotherms fit the Freundlich equation x/m=K_dC^1/n. The K_d values increase with the increase of the fly ash content. The isotherms seem to fit the S type, in mixtures of soil with a fly ash content from 0 to 10%, which implies that adsorption becomes easier as the concentration in the liquid phase increases. In mixtures of soil with a fly ash content from 25 to 50% the isotherms become L type and correspond to a decrease of site availability as the solution concentration increases. Finally in mixtures of soil with a fly ash content over 50%, C type adsorption was observed which correspond to a constant partition of the insecticides between the bulk solution and the adsorbent. Mass balance estimations show that the mean percent amounts of insecticides for a range of concentration 0.5–15 mg/l, removed by adsorption in the soil sample are 81.56 % for ethyl parathion, 48.97 % for methyl parathion, 67.06 % for fenitrothion and 86.65 % for fenthion. The adsorption increases as the fly ash content increased and reach the 100% in the “pure” fly ash. The adsorbed amounts of insecticides in mixtures of soils with >50% fly ash content, are up to 99%. In contrast, the amounts of desorption in water decrease as the fly ash content increase.

The results of this research demonstrate that the fly ash shows a significant capacity for adsorption of organophosphorus compounds from aqueous solution and can be used for pesticide removal process.     

Headspace solid-phase microextraction for the gas chromatographic analysis of organophosphorus insecticides in vegetables

Residues of organophosphorus insecticides (diazinon, methyl parathion, fenitrothion, malathion, and parathion) were determined in 13 different vegetable matrixes by headspace solid-phase microextraction performed with a polydimethyl-siloxane fiber (100 microm). Determination was carried out by gas chromatography with a nitrogen-phosphorus detector. Limits of detection and quantification were < 0.005 and 0.017 mg/kg, respectively; thus, the limits of maximum residue levels (MRLs) required by European regulations can be verified without difficulty. Pesticide residues were found in 38% of the 125 fresh commercial samples (imported and domestic) that were analyzed. Residues of methyl parathion and parathion, which were withdrawn in Greece in 2003, were detected in 36.8 and 4% of all samples, respectively. The MRLs were exceeded overall by 1%.     

Tip-assisted ambient electric arc ionization mass spectrometry for rapid detection of trace organophosphorus pesticides in strawberry

In this study, an ambient mass spectrometry (AMS) based method was developed for rapid detection of organophosphorus pesticides in strawberry. This method combines an electric arc and a microsyringe tip to realize tip-assisted ambient electric arc ionization (TAAEAI). A high-voltage electric arc can be applied to the microsyringe tip to generate an electric field, which results in corona discharge at the microsyringe tip. The juiced strawberry sample loaded on the tip could be directly ionized with TAAEAI and then analyzed by a mass spectrometer. TAAEAI-MS was successfully applied to analyze 6 organophosphorus pesticides in three strawberry samples. Malathion and profenofos were detected from the investigated strawberry samples. This method could quantitatively determine the contents of organophosphorus pesticides in strawberry with high reproducibility, high precision, and high sensitivity. Sample matrices did not interfere with the pesticide analysis. The recoveries of organophosphorus pesticides spiked in strawberry samples varied between 82.6% and 116% with relative standard deviations (RSDs) less than 9.2%. The limits of detection (LODs) varied between 0.0124 µg/g and 0.0245 µg/g, while the limits of quantification (LOQs) varied between 0.0413 µg/g and 0.0817 µg/g. The coefficients of determination (R²) of the method were determined to be >0.995. The method established here may have potential application in the detection of organophosphorus pesticides in vegetables and fruits.     

Separation of pesticides by capillary gas chromatography. Part 2: Organophosphorus insecticides

This article considers the separation of 23 organophosphorus insecticides to which two metabolites have been added. The high resolution of the column permits detection of the Z and E isomers of three of these insecticides.     

Hazard Evaluation of Ten Organophosphorus Insecticides Against the Midge,Chironomus riparius via QSAR

Abstract

Toxicities of ten organophosphorus (OP) insecticides were measured against midge larvae (Chironomus riparius) under varying temperature (11, 18, and 25°C) and pH (6, 7, and 8) conditions and with and without sediment. Toxicity usually increased with increasing temperature and was greater in the absence of sediment. No trend was found with varying pH. A series of unidimensional parameters and multidimensional models were used to describe the changes in toxicity. Log K _ow was able to explain about 40–60% of the variability in response data for aqueous exposures while molecular volume and aqueous solubility were less predictive. Likewise, the linear solvation energy relationship (LSER) model only explained 40–70% of the response variability, suggesting that factors other than solubility were most important for producing the observed response. Molecular connectivity was the most useful for describing the variability in the response. In the absence of sediment, ¹χ ^v and ³κ were best able to describe the variation in response among all compounds at each pH (70–90%). In the presence of sediment, even molecular connectivity could not describe the variability until the partitioning potential to sediment was accounted for by assuming equilibrium partitioning. After correcting for partitioning, the same molecular connectivity terms as in the aqueous exposures described most of the variability, 61–87%, except for the 11°C data where correlations were not significant. Molecular connectivity was a better tool than LSER or the unidimensional variables to explain the steric fitness of OP insecticides which was crucial to the toxicity.     

Determination of organophosphorus pesticide residues in fruits by gas chromatography with ITD and NPD detection

Summary Several widely used organophosphorus insecticides, diazinon, methyl-parathion, fenitrothion, malathion, fenthion and methidathion were selected for inclusion in this work. A comparative study of the multiresidue determination of these compounds in citrus fruit and grapes has been carried out by gas chromatography with nitrogen-phosphorus and ion trap detection. Samples were spiked with 0.1, 0.5 and 1 mg kg^–1 of each pesticide and blended in a Sorvall homogeniser with ethyl acetate. Column clean-up on Florisil was necessary for citrus peel extracts. The average recoveries varied from 81 to 107% with a relative standard deviation between 0.3 and 9.5% for GC-ITD and from 86 to 104% with a relative standard deviation ranging from 1.4 to 8.0% for GC-NPD. The detection limit of the method was 10 ng g^–1 or less for each organophosphorus insecticide, with both detectors. This method was applied to the analysis of treated lemons and 0.25 mg kg^–1 of fenitrothion in fruit was detected a week after treatment and identified by its mass spectrum. The results obtained showed that the proposed methods are reproducible and sensitive enough for the simultaneous determination of these insecticides in fruits at residue level.     

Measurement of permethrin,deltamethrin and malathion pesticide residues in the wheat flour and breads and probabilistic health risk assessment: a case study in Kermanshah,Iran

ABSTRACT

This study was conducted to investigate the residues of pyrethroid and organophosphorus pesticide in flour and breads which were collected from local markets in Kermanshah province, Iran. Four different types of breads and two types of flour samples with high distribution were taken from market and their residues of pesticides were measured. A simple dispersive liquid–liquid microextraction (DLLME) method with solidification of floating organic drop was developed for the measurement. The health risk of these pesticides on adults and children health was assessed by target hazard quotient (THQ) using Monte Carlo simulation (MCS) method. About, 15% and 11.1% of total samples contained detectable levels of deltamethrin and malathion, respectively. None of the tested samples showed any permethrin residue. The results from all samples showed that none of the pesticides exceeded the maximum residue limits (MRLs). About 85% of pesticide residue detections were observed in tropical and mild weather area which is due to high consumption rate of insecticides in these areas. The percentile 95% of THQ is due to bread ingestion content of deltamethrin which was 0.033 and 0.070 for the adults and children, respectively, while this value for malathion was found to be, 0.015 and 0.030, respectively. In the adults and children for both deltamethrin and malathion, the percentile 95% of THQ value were lower than 1 (acceptable level). The non-carcinogenic health risk assessment indicated that bread consumers in Kermanshah province are not at a considerable risk because of deltamethrin and malathion.     

基于磁性共轭微孔聚合物的超高效液相色谱-串联质谱法测定果蔬中7种有机磷杀虫剂

建立了基于磁性共轭微孔聚合物的磁固相萃取-超高效液相色谱-串联质谱（UPLC-MS/MS）测定果蔬中7种有机磷杀虫剂的方法。将亚苯基亚乙炔基修饰的Fe₃O₄与1,3,5-三溴苯、1,3,5-三乙炔苯反应,制备磁性共轭微孔聚合物,材料能有效吸附共轭结构的有机磷杀虫剂,并在外磁场中实现便捷磁分离。方法的检出限（LOD）为0.12~5.0 ng/kg,加标回收率为80.8%~125%,相对标准偏差（RSD）小于6%（n=5）。方法应用于分析市场上果蔬样品中7种有机磷杀虫剂,检出含量为1.1~500.0 ng/kg。该方法灵敏度高,准确可靠,对果蔬中有机磷杀虫剂的检测具有良好的应用潜力。     

Multi-residue method for trace pesticide analysis in soils by LC-QQQ-MS/MS and its application to real samples

ABSTRACT

A method for the simultaneous determination of 30 pesticides residues in soil was developed and validated. Among the studied agrochemicals, there are herbicides (auxines, sulfonylureas, fops, imidazolinones), fungicides (azoles) and insecticides (organophosphorus) widely used in extensive agricultural activities in Uruguay. Five methods with different extraction times, type and amount of solvent, as well as the possibility of a clean-up step were compared in terms of percentage of recovery and repeatability. The final method was based on the extraction of the pesticides’ residues from soil using two successive solvent extraction steps. First, the soil was extracted with methanol in an orbital shaker for 4 h. Secondly, the solid residue was re-extracted overnight with ultrapure water. The methanolic extract was concentrated under vacuum, whereas the aqueous solution was passed through an OASIS HLB® cartridge, eluted with an appropriate solvent and concentrated under nitrogen stream. Both extracts were finally combined and analysed by LC-QQQ-MS/MS using the Document SANTE/11,945/2015 criteria. Recovery percentages at 1 and 10 μg kg^?1 for the studied compounds were in the range 70106% with relative standard deviations below 19 %. The quantification was performed using matrix-matched calibration curves as some compounds presented very strong signal suppression. Residuals of the matrix-matched calibration curves were below 20% for all the validated analytes. The quantification limit was1 μg kg^?1. The method also allows the screening of 11 pesticides in soil. Sixty-five real samples collected from regions where the use of pesticides is intensive were analysed. Quinclorac, tebuconazole, penoxsulam and clomazone were the most frequently pesticides detected.     

Synthesis,Structures, and Fungitoxicity of Novel Organophosphorus Compounds

Abstract

A series of biologically active organophosphorus compounds have been synthesized by the reactions of O,O-diethylchlorophosphate with Schiff bases derived from 5-(phenyl/substituted phenyl)-2-hydrazino-1,3,4-oxadiazole and salicylaldehyde/2-hydroxyacetophenone. The compounds have been characterized on the basis of analyses and spectral (IR, ¹H, ¹³C NMR) data. Fungicidal activities of these derivatives against Colletotrichum falcatum, Fusarium oxysporum, and Curvularia pallescence have been evaluated. All compounds showed moderate to significant antifungal activity.