The application of organophosphorus pesticides (OPPs) increased gradually because of the rise in global food demand that triggered the agriculture sector to increase the production, leading to OPP residues in the surface water. This study elucidated the presence of OPPs and estimated its ecological risk in the riverine ecosystem of the urbanised Linggi River, Negeri Sembilan, Malaysia. The OPP concentration in surface water was determined using solid-phase extraction method and high-performance liquid chromatography coupled with diode array detection. Further, the ecological risk was estimated by using the risk quotient (RQ) method. The three OPPs, i.e. chlorpyrifos, diazinon, and quinalphos were detected with mean concentrations of 0.0275 µg/L, 0.0328 µg/L, and 0.0362 µg/L, respectively. The OPPs were at high risk (in general and worst cases) under acute exposure. The estimated risk of diazinon was observed as medium for general (RQm = 0.5857) and high for worst cases (RQex = 4.4678). Notably, the estimated risk for chlorpyrifos was high for both general and worst cases (RQm = 1.9643 and RQex = 11.5643) towards the aquatic ecosystem of the Linggi River. Chronic risk of quinalphos remains unknown because of the absence of toxicity endpoints. This study presented clear knowledge regarding OPP contamination and possible risk for aquatic ecosystems. Hence, OPPs should be listed as one of the main priority contaminants in pesticide mitigation management in the future.
This study investigates how field practices in handling and applying pesticides influence the long-term patterns of professional agricultural operators' exposure to pesticides. It presents the first use of a comprehensive pesticide application dataset collected on behalf of the European Food Safety Authority with 50 operators selected to cover arable and orchard cropping systems in Greece, Lithuania and the UK. Exposure was predicted based on the harmonised Agricultural Operator Exposure Model (AOEM) and compared with Acceptable Operator Exposure Levels (AOELs). The amount of pesticides handled by individual operators across a cropping season was largest in the UK arable and orchard systems (median 580 and 437kg active substance, respectively), intermediate for the arable systems in Greece and Lithuania (151 and 77kg, respectively), and smallest in the Greek orchard system (22kg). Overall, 30 of the 50 operators made at least one application within a day with predicted exposure greater than the AOEL. The rate of AOEL exceedance was greatest in the Greek cropping systems (8 orchard operators, 2.8-16% of total applications; 7 arable operators, 1.1-14% of total applications), and least for the Lithuanian arable system (2 operators, 2.9-4.5% of total applications). Instances in Greece when predicted exposure exceed the AOEL were strongly influenced by the widespread use of wettable powder formulations (>40% of the total pesticide active substance handled for 11 of the 20 Greek operators). In contrast, the total area of land treated with an active substance on a single day was more important in the UK and Lithuania (95th percentile observed value was 132 and 19haday-1 for UK arable and orchard systems, respectively). Study findings can be used to evaluate current assumptions in regulatory exposure calculations and to identify situations with potential risk that require further analysis including measurements of exposure to validate model estimations.
Occupational exposure to pesticide mixtures comprising active substance(s) and/or co-formulant(s) with known/possible endocrine-disrupting activity was assessed using long-term activity records for 50 professional operators representing arable and orchard cropping systems in Greece, Lithuania, and the UK. Exposure was estimated using the harmonised Agricultural Operator Exposure Model, and risk was quantified as a point of departure index (PODI) using the lowest no observed (adverse) effect level. Use of substances with known/possible endocrine activity was common, with 43 of the 50 operators applying at least one such active substance on more than 50% of spray days; at maximum, one UK operator sprayed five such active substances and 10 such co-formulants in a single day. At 95th percentile, total exposure was largest in the UK orchard system (0.041 × 10-2 mg kg bw-1 day-1) whereas risk was largest in the Greek cropping systems (PODI 0.053 × 10-1). All five cropping systems had instances indicating potential for risk when expressed at a daily resolution (maximum PODI 1.2-10.7). Toxicological data are sparse for co-formulants, so combined risk from complex mixtures of active substances and co-formulants may be larger in reality.
Pesticides are of great concern because of their existence in ecosystems at trace concentrations. Worldwide pesticide use and its ecological impacts (i.e., altered environmental distribution and toxicity of pesticides) have increased over time. Exposure and toxicity studies are vital for reducing the extent of pesticide exposure and risk to the environment and humans. Regional regulatory actions may be less relevant in some regions because the contamination and distribution of pesticides vary across regions and countries. The risk quotient (RQ) method was applied to assess the potential risk of organophosphorus pesticides (OPPs), primarily focusing on riverine ecosystems. Using the available ecotoxicity data, aquatic risks from OPPs (diazinon and chlorpyrifos) in the surface water of the Langat River, Selangor, Malaysia were evaluated based on general (RQm) and worst-case (RQex) scenarios. Since the ecotoxicity of quinalphos has not been well established, quinalphos was excluded from the risk assessment. The calculated RQs indicate medium risk (RQm = 0.17 and RQex = 0.66; 0.1 ≤ RQ 1 (high risk) was observed for both the general and worst cases of chlorpyrifos, but only for the worst cases of diazinon at all sites from downstream to upstream regions. Thus, chlorpyrifos posed a higher risk than diazinon along the Langat River, suggesting that organisms and humans could be exposed to potentially high levels of OPPs.
A new sol-gel hybrid coating, polydimethylsiloxane-2-hydroxymethyl-18-crown-6 (PDMS-2OHMe18C6) was prepared in-house for use in solid phase microextraction (SPME). The three compositions produced were assessed for its extraction efficiency towards three selected organophosphorus pesticides (OPPs) based on peak area extracted obtained from gas chromatography with electron capture detection. All three compositions showed superior extraction efficiencies compared to commercial 100 microm PDMS fiber. The composition showing best extraction performance was used to obtain optimized SPME conditions: 75 degrees C extraction temperature, 10 min extraction time, 120 rpm stirring rate, desorption time 5 min, desorption temperature 250 degrees C and 1.5% (w/v) of NaCl salt addition. The method detection limits (S/N=3) of the OPPs with the new sol-gel hybrid material ranged from 4.5 to 4.8 ng g(-1), which is well below the maximum residue limit set by Codex Alimentarius Commission and European Commission. Percentage recovery of OPPs from strawberry, green apple and grape samples with the new hybrid sol-gel SPME material ranged from 65 to 125% with good precision of the method (%RSD) ranging from 0.3 to 7.4%.
A sensitive and selective gas chromatography with mass spectrometry method was developed for the simultaneous determination of three organophosphorus pesticides, namely, chlorpyrifos, malathion, and diazinon in three different food commodities (milk, apples, and drinking water) employing solid-phase extraction for sample pretreatment. Pesticide extraction from different sample matrices was carried out on Chromabond C18 cartridges using 3.0 mL of methanol and 3.0 mL of a mixture of dichloromethane/acetonitrile (1:1 v/v) as the eluting solvent. Analysis was carried out by gas chromatography coupled with mass spectrometry using selected-ion monitoring mode. Good linear relationships were obtained in the range of 0.1-50 μg/L for chlorpyrifos, and 0.05-50 μg/L for both malathion and diazinon pesticides. Good repeatability and recoveries were obtained in the range of 78.54-86.73% for three pesticides under the optimized experimental conditions. The limit of detection ranged from 0.02 to 0.03 μg/L, and the limit of quantification ranged from 0.05 to 0.1 μg/L for all three pesticides. Finally, the developed method was successfully applied for the determination of three targeted pesticides in milk, apples, and drinking water samples each in triplicate. No pesticide was found in apple and milk samples, but chlorpyrifos was found in one drinking water sample below the quantification level.
A new sol-gel hybrid methyltrimethoxysilane-chloropropyltriethoxysilane was prepared as sorbent for solid-phase extraction. The extraction efficiency of the prepared sol-gel hybrid methyltrimethoxysilane-chloropropyltriethoxysilane was assessed by using three selected organophosphorus pesticides, namely, chlorpyrifos, profenofos, and malathion. Gas chromatography-mass spectrometry was used for detection of organophosphorus pesticides. Several vital parameters were optimized to identify the best extraction conditions. Under the optimum extraction conditions, solid-phase extraction-methyltrimethoxysilane-chloropropyltriethoxysilane method showed good linearity range (0.05-1 μg/mL) with coefficient of determination more than 0.995. The limits of detection obtained were in the range of 0.01-0.07 μg/mL and limits of quantification ranging from 0.03 to 0.21 μg/mL. The limits of detection obtained for the developed method were 2.3-6.5× lower than the limits of detection of commercial octadecyl silica sorbent. Real samples analysis was carried out by applying the developed method on red apple and purple grape samples. The developed method exhibited good recoveries (88.33-120.7%) with low relative standard deviations ranging from 1.6 to 3.3% compared to commercial octadecyl silica sorbent, which showed acceptable recoveries (70.3-100.2%) and relative standard deviations (6.3-8.8%). The solid-phase extraction-methyltrimethoxysilane-chloropropyltriethoxysilane method is presented as an alternative extraction method for determination of organophosphorus pesticides.
Alkylphenols and most pesticides, especially organochlorine pesticides are endocrine-disrupting chemicals and they usually mimic the female hormone, estrogen. Using these chemicals in our environment would eventually lead us to consume them somehow in the food web. Several rivers in the State of Selangor, Malaysia were selected to monitor the level of alkylphenols and pesticides contamination for several months. The compounds were extracted from the water samples using liquid-liquid extraction method with dichloromethane and ethyl acetate as the extracting solvents. The alkylphenols and pesticides were analyzed by selected ion monitoring (SIM) mode using the quadrapole detector in Shimadzu QP-5000 gas chromatograph-mass spectrometer (GCMS). Recovery of most alkylphenols and pesticides were in the range of 50% to 120%. Trace amounts of the compounds were detected in the river water samples, mainly in the range of parts per trillion. This technique of monitoring the levels of endocrine-disruptors in river water is consistent and cost effective.
A simple and effective multiresidue method based on precipitation at low temperature followed by matrix solid-phase dispersion-sonication was developed and validated to determine dimethoate, malathion, carbaryl, simazine, terbuthylazine, atrazine and diuron in palm oil using liquid chromatography time-of-flight mass spectrometry (LC-TOF-MS). Liquid-liquid extraction (LLE) followed by low temperature method were optimized by studying the effect of type and volume of organic solvent (acetonitrile, acetonitrile:n-hexane (3:2 v/v) and acetone) and time of freezing to obtain high recovery yield and low co-extract fat residue in the final extract. The optimal conditions for matrix solid-phase dispersion (MSPD) were obtained using 5 g of palm oil, 2 g of primary secondary amine (PSA) as dispersing sorbent, 1 g of graphitized carbon black (GCB) as clean-up sorbent and 15 mL of acetonitrile as eluting solvent under conditions of 15 min ultrasonication at room temperature. Method validation was performed in order to study sensitivity, linearity, precision, and accuracy. Average recoveries at three concentration levels (25, 50 and 100 μg kg(-1)) were found in the range of 72.6-91.3% with relative standard deviations between 5.3% and 14.2%. Detection and quantification limits ranged from 1.5 to 5 μg kg(-1) and from 2.5 to 9 μg kg(-1), respectively.
A heavy-metal assay has been developed using bromelain, a protease. The enzyme is assayed using casein as a substrate with Coomassie dye to track completion of hydrolysis of casein. In the absence of inhibitors, casein is hydrolysed to completion, and the solution is brown. In the presence of metal ions such as Hg2+ and Cu2+, the hydrolysis of casein is inhibited, and the solution remains blue. Exclusion of sulfhydryl protective agent and ethylenediaminetetraacetic in the original assay improved sensitivity to heavy metals several fold. The assay is sensitive to Hg2+ and Cu2+, exhibiting a dose-response curve with an IC50 of 0.15 mg 1(-1) for Hg2+ and a one-phase binding curve with an IC50 of 0.23 mg 1(-1) for Cu2+. The IC50 value for Hg2+ is found to be lower to several other assays such as immobilized urease and papain assay, whilst the IC50 value for Cu2+ is lower than immobilized urease, 15-min Microtox, and rainbow trout.
Whole cell biosensors always face the challenge of low stability of biological components and short storage life. This paper reports the effects of poly(2-hydroxyethyl methacrylate) (pHEMA) immobilization on a whole cell fluorescence biosensor for the detection of heavy metals (Cu, Pb, Cd), and pesticides (dichlorophenoxyacetic acid (2,4-D), and chlorpyrifos). The biosensor was produced by entrapping the cyanobacterium Anabaena torulosa on a cellulose membrane, followed by applying a layer of pHEMA, and attaching it to a well. The well was then fixed to an optical probe which was connected to a fluorescence spectrophotometer and an electronic reader. The optimization of the biosensor using several factors such as amount of HEMA and drying temperature were undertaken. The detection limits of biosensor without pHEMA for Cu, Cd, Pb, 2,4-D and chlorpyrifos were 1.195, 0.027, 0.0100, 0.025 and 0.025 µg/L respectively. The presence of pHEMA increased the limits of detection to 1.410, 0.250, 0.500, 0.235 and 0.117 µg/L respectively. pHEMA is known to enhance the reproducibility of the biosensor with average relative standard deviation (RSD) of ±1.76% for all the pollutants tested, 48% better than the biosensor without pHEMA (RSD = ±3.73%). In storability test with Cu 5 µg/L, the biosensor with pHEMA performed 11.5% better than the test without pHEMA on day-10 and 5.2% better on day-25. pHEMA is therefore a good candidate to be used in whole cell biosensors as it increases reproducibility and enhances biosensor storability.
This study investigates the presence and distribution of organochlorine pesticides in streams and the lake in the Sembrong Lake Basin in Malaysia. The catchment of Sembrong Lake has been converted to agricultural areas over the past 30 years, with oil palm plantations and modern agricultural farming being the main land use. Surface water samples were collected from eight sites comprising the stream and lake and analysed for 19 organochlorine pesticides (OCPs). In situ measurement of temperature, dissolved oxygen, pH and conductivity were also undertaken at each site. Aldrin, endrin, δ-BHC, 4,4-DDT, methoxychlor and endosulfan were the main OCPs detected in the lake basin. The total OCP concentration ranged between 5.42 and 349.2 ng/L. The most frequently detected OCPs were δ-BHC, heptachlor and aldrin. The maximum values detected were 23.0, 43.2 and 50.4 ng/L respectively. The highest concentration of OCPs was attributed to 4,4-DDT, but such high residue was rare and only detected once. Other OCP residues were low. Significant differences in the mean values were observed between lake and stream for dichlorodiphenyldichloroethylene (DDE) and α-endosulfan concentration (p
A method to determine six organochlorine and three pyrethroid pesticides in grape, orange, tomato, carrot and green mustard based on solvent extraction followed by solid phase extraction (SPE) clean-up is described. The pesticides were spiked into the sample prior to analysis, extracted with ethyl acetate, evaporated and reconstituted with a solvent mixture of acetone:n-hexane (3:7). Three different sorbents (Strong Anion Exchanger/Primary Secondary Amine (SAX/PSA), Florisil and C18) were used for the clean-up step. Pesticides were eluted with 5mL of acetone:n-hexane (3:7, v/v) and determined by gas chromatography and electron-capture detection (GC-ECD). SAX/PSA was the sorbent, which provided chromatograms with less interference and the mean recoveries obtained were within 70-120% except for captafol. The captafol recoveries for grape were within acceptable range with C18 clean-up column.
A study on the quality of water abstracted for potable use was conducted in the Selangor River basin from November 2008 to July 2009. Seven sampling sites representing the intake points of water treatment plants in the basin were selected to determine the occurrence and level of 15 organochlorine pesticides (OCPs), six phthalate esters (PAEs) and bisphenol A (BPA). Results indicated OCPs were still detected regularly in 66.1 % of the samples with the Σ(15)OCPs ranging from 0.6-25.2 ng/L. The first data on PAEs contamination in the basin revealed Σ(6)PAEs concentrations were between 39.0 and 1,096.6 ng/L with a median concentration of 186.0 ng/L while BPA concentration ranged from <1.2 to 120.0 ng/L. Although di-n-butyl phthalate was detected in all the samples, concentrations of di-ethyl(hexyl)phthalate were higher. Sampling sites located downstream recorded the highest concentrations, together with samples collected during the dry season. Comparison of the detected contaminants with the Department of Environment Water Quality Index (DOE-WQI) showed some agreement between the concentration and the current classification of stream water. While the results suggest that the sites were only slightly polluted and suitable to be used as drinking water source, its presence is cause for concern especially to the fragile firefly "Pteroptyx tener" ecosystem located further downstream.
A study to assess the level of organochlorine pesticides (OCPs) and bisphenol A (BPA) in edible marine biota collected from coastal waters of Malaysia was conducted using GC-MS and SPE extraction. An analytical method was developed and validated to measure the level of 15 OCPs and BPA simultaneously from five selected marine species. It was observed that some samples had low levels of p,p'-DDE, p,p'-DDT and p,p'- DDD ranging from 0.50 ng g(-1) to 22.49 ng g(-1) dry weight (d.w) but significantly elevated level of endosulfan I was detected in a stingray sample at 2880 ng g(-1) d.w. BPA was detected in 31 out of 57 samples with concentration ranging from below quantification level (LOQ: 3 ng g(-1)) to 729 ng g(-1) d.w. The presence of OCPs is most likely from past use although there is also indication of illegal use in recent times. The study also reveals that BPA is more widely distributed in coastal species caught off the coast of the most developed state. The potential health risk from dietary intakes of OCPs and BPA from the analysed fish species was negligible.
A new sample pre-treatment technique termed cone-shaped membrane liquid phase microextraction (CSM-LPME) was developed and combined with micro-liquid chromatography (micro-LC) for the determination of selected pesticides in water samples. Four pesticides (hexaconazole, procymidone, quinalphos and vinclozolin) were considered as target analytes. Several important extraction parameters such as types of extraction solvent, agitation rate, pH value, total exposure time and effect of salt and humic acids were optimized. Enrichment factors of > 50 folds were easily achieved within 20 min of extraction. The analytical data demonstrated relative standard deviations for the reproducibility of the optimized CSM-LPME method ranging from 6.3 to 7.5%. The correlation coefficients of the calibration curves were at least 0.9995 across a concentration range of 2-100 microg/L. The detection limits for all the analytes were found to be in the range of 1.1-1.9 microg/L.
A new graphene-based tetraethoxysilane-methyltrimethoxysilane sol-gel hybrid magnetic nanocomposite (Fe3O4@G-TEOS-MTMOS) was synthesised, characterized and successfully applied in magnetic solid-phase extraction (MSPE) for simultaneous analysis of polar and non-polar organophosphorus pesticides from several water samples. The Fe3O4@G-TEOS-MTMOS nanocomposite was characterized using Fourier transform-infrared spectroscopy, energy-dispersive X-ray spectroscopy, field emission scanning electron microscopy and X-ray diffraction. Separation, determination and quantification were achieved using gas chromatography coupled with micro electron capture detector. Adsorption capacity of the sorbent was calculated using Langmuir equation. MSPE was linear in the range 100-1000 pg mL(-1) for phosphamidon and dimethoate, and 10-100 pg mL(-1) for chlorpyrifos and diazinon, with limit of detection (S/N = 3) of 19.8, 23.7, 1.4 and 2.9 pg mL(-1) for phosphamidon, dimethoate, diazinon and chlorpyrifos, respectively. The LODs obtained is well below the maximum residual level (100 pg mL(-1)) as set by European Union for pesticides in drinking water. Acceptable precision (%RSD) was achieved for intra-day (1.3-8.7%, n = 3) and inter-day (7.6-17.8%, n = 15) analyses. Fe3O4@G-TEOS-MTMOS showed high adsorption capacity (54.4-76.3 mg g(-1)) for the selected OPPs. No pesticide residues were detected in the water samples analysed. Excellent extraction recoveries (83-105%) were obtained for the spiked OPPs from tap, river, lake and sea water samples. The newly synthesised Fe3O4@G-TEOS-MTMOS showed high potential as adsorbent for OPPs analysis.
A liquid-phase microextraction coupled with LC method has been developed for the determination of organophosphorus pesticides (methidation, quinalphos and profenofos) in drinking water samples. In this method, a small amount (3 microL) of isooctane as the acceptor phase was introduced continually to fill-up the channel of a 1.5 cm polypropylene hollow fiber using a microsyringe while the hollow fiber was immersed in an aqueous donor solution. A portion of the acceptor phase (ca. 0.4 microL) was first introduced into the hollow fiber and additional amounts (ca. 0.2 microL) of the acceptor phase were introduced to replenish at intervals of 3 min until set end of extraction (40 min). After extraction, the acceptor phase was withdrawn and transferred into a 2 mL vial for a drying step prior to injection into a LC system. Parameters that affect the extraction efficiency were studied including the organic solvent, length of fiber, volume of acceptor and donor phase, stirring rate, extraction time, and effect of salting out. The proposed method provided good enrichment factors of up to 189.50, with RSD ranging from 0.10 to 0.29%, analyte recoveries of over 79.80% and good linearity ranging from 10.0 to 1.25 mg/L. The LOD ranged from 2.86 to 82.66 microg/L. This method was applied successfully to the determination of organophosphorus pesticides in selected drinking water samples.
Increasing urbanization and changes in land use in Langat river basin lead to adverse impacts on the environment compartment. One of the major challenges is in identifying sources of organic contaminants. This study presented the application of selected chemometric techniques: cluster analysis (CA), discriminant analysis (DA), and principal component analysis (PCA) to classify the pollution sources in Langat river basin based on the analysis of water and sediment samples collected from 24 stations, monitored for 14 organic contaminants from polycyclic aromatic hydrocarbons (PAHs), sterols, and pesticides groups. The CA and DA enabled to group 24 monitoring sites into three groups of pollution source (industry and urban socioeconomic, agricultural activity, and urban/domestic sewage) with five major discriminating variables: naphthalene, pyrene, benzo[a]pyrene, coprostanol, and cholesterol. PCA analysis, applied to water data sets, resulted in four latent factors explaining 79.0% of the total variance while sediment samples gave five latent factors with 77.6% explained variance. The varifactors (VFs) obtained from PCA indicated that sterols (coprostanol, cholesterol, stigmasterol, β-sitosterol, and stigmastanol) are strongly correlated to domestic and urban sewage, PAHs (naphthalene, acenaphthene, pyrene, benzo[a]anthracene, and benzo[a]pyrene) from industrial and urban activities and chlorpyrifos correlated to samples nearby agricultural sites. The results demonstrated that chemometric techniques can be used for rapid assessment of water and sediment contaminations.
The present study was undertaken to determine the content of six minerals, five trace elements, and ten pesticide residues in honeys originating from different regions of Malaysia. Calcium (Ca), magnesium (Mg), iron (Fe), and zinc (Zn) were analyzed by flame atomic absorption spectrometry (FAAS), while sodium (Na) and potassium (K) were analyzed by flame emission spectrometry (FAES). Trace elements such as arsenic (As), lead (Pb), cadmium (Cd), copper (Cu), and cobalt (Co) were analyzed by graphite furnace atomic absorption spectrometry (GFAAS) following the microwave digestion of honey. High mineral contents were observed in the investigated honeys with K, Na, Ca, and Fe being the most abundant elements (mean concentrations of 1349.34, 236.80, 183.67, and 162.31 mg/kg, resp.). The concentrations of the trace elements were within the recommended limits, indicating that the honeys were of good quality. Principal component analysis reveals good discrimination between the different honey samples. The pesticide analysis for the presence of organophosphorus and carbamates was performed by high performance liquid chromatography (HPLC). No pesticide residues were detected in any of the investigated honey samples, indicating that the honeys were pure. Our study reveals that Malaysian honeys are rich sources of minerals with trace elements present within permissible limits and that they are free from pesticide contamination.