An HS-SPME method was developed using multivariate experimental designs, which was conducted in two stages. The significance of each factor was estimated using the Plackett-Burman (P-B) design, for the identification of significant factors, followed by the optimization of the significant factors using central composite design (CCD). The multivariate experiment involved the use of Minitab® statistical software for the generation of a 2(7-4) P-B design and CCD matrices. The method performance evaluated with internal standard calibration method produced good analytical figures of merit with linearity ranging from 1 to 500 μg/kg with correlation coefficient greater than 0.99, LOD and LOQ were found between 0.35 and 8.33 μg/kg and 1.15 and 27.76 μg/kg respectively. The average recovery was between 73% and 118% with relative standard deviation (RSD=1.5-14%) for all the investigated pesticides. The multivariate method helps to reduce optimization time and improve analytical throughput.
Solid-phase microextraction (SPME) is a solvent-less sample preparation method which combines sample preparation, isolation, concentration and enrichment into one step. In this study, multivariate strategy was used to determine the significance of the factors affecting the solid phase microextraction of pesticide residues (fenobucarb, diazinon, chlorothalonil and chlorpyrifos) using a randomised factorial design. The interactions and effects of temperature, time and salt addition on the efficiency of the extraction of the pesticide residues were evaluated using 2(3) factorial designs. The analytes were extracted with 100 μm PDMS fibres according to the factorial design matrix and desorbed into a gas chromatography-mass spectrometry detector. The developed method was applied for the analysis of apple samples and the limits of detection were between 0.01 and 0.2 μg kg(-)(1), which were lower than the MRLs for apples. The relative standard deviations (RSD) were between 0.1% and 13.37% with average recovery of 80-105%. The linearity ranges from 0.5-50 μg kg(-)(1) with correlation coefficient greater than 0.99.
The sample preparation step has been identified as the bottleneck of analytical methodology in chemical analysis. Therefore, there is need for the development of cost-effective, easy to operate, and environmentally friendly miniaturized sample preparation technique. The microextraction techniques combine extraction, isolation, concentration, and introduction of analytes into analytical instrument, to a single and uninterrupted step, and improve sample throughput. The use of liquid-phase microextraction techniques for the analysis of pesticide residues in fruits and vegetables are discussed with the focus on the methodologies employed by different researchers and their analytical performances. Analytes are extracted using water-immiscible solvents and are desorbed into gas chromatography, liquid chromatography, or capillary electrophoresis for identification and quantitation.
This paper reviews the application of various modes of solid-phase microextraction (SPME) for the analysis of pesticide residues in fruits and vegetables. SPME is a simple extraction technique that eliminates the use of solvent, and it is applied for the analysis of both volatile and nonvolatile pesticides. SPME has been successfully coupled to both GC and LC. The coupling with GC has been straightforward and requires little modification of existing equipment, but interfacing with LC has proved challenging. The external standard calibration technique is widely used for quantification, while standard addition and internal or surrogate standards are mainly used to account for matrix effects. All parameters that affect the extraction of pesticide residues from fruits and vegetables, and therefore need to be optimized, are also reviewed. Details of the characteristics of analytical procedures and new trends in fiber production using sol-gel technology and molecularly imprinted polymers are discussed.
This review presents the application of carbon nanotubes as sorbent materials in the analysis of pesticide residues in fruits and vegetables. The advantages, limitations, and challenges of carbon nanotubes, with respect to their use in analytical chemistry, are presented. The efficiency of their application as extraction sorbent materials (in terms of LOD, LOQ, linearity, relative recovery, and RSD) in SPE, solid-phase microextraction, multi-plug filtration clean-up, matrix solid-phase dispersion, and the quick, easy, cheap, effective, rugged and safe method is reported. The synthesis, functionalization, purification, and characterization methods of carbon nanotubes are also discussed.
Land application of sludge as fertilizers is a way of disposal and recycling of sludge. However, public concern has arisen due to the fact that organic contaminants in sludge may ultimately enter the food chain. Hence the need arises to analyse the organic contaminants such as PAHs and OCPs in sludge. In this study, Soxhlet was utilised as the extraction method and the extracts subjected to extensive cleanup via either silica columns or solid phase extraction cartridges prior to analysis using gas chromatography or high performance liquid chromatography. Sludge samples were collected from the drying beds of oxidation ponds in three locations in South Johore. OCPs such as heptachlor, dieldrin and pp-DDT were detected in low amounts (52-159 mg/kg) whereas PAHs such as naphthalene, phenanthrene, fluoranthene and benzo(a)pyrene were detected in the range of 0.2-5.5 mg/kg dry mass. Subcritical water extraction (SWE) recovery studies of PAHs were also performed from spiked sludge samples. Although a recovery range of 41-68% was obtained using the SWE method, the results indicated the usefulness of the technique as an alternative to Soxhlet extraction for the analysis of PAHs in sludge samples.
Pesticides are the leading defence against pests, but their unsafe use reciprocates the pesticide residues in highly susceptible food and is becoming a serious risk for human health. In this study, mint extract and riboflavin were tested as photosensitisers in combination with light irradiation of different frequencies, employed for various time intervals to improve the photo-degradation of deltamethrin (DM) and lambda cyhalothrin (λ-CHT) in cauliflower. Different source of light was studied, either in ultraviolet range (UV-C, 254 nm or UV-A, 320-380 nm) or sunlight simulator (> 380-800 nm). The degradation of the pesticides varied depending on the type of photosensitiser and light source. Photo-degradation of the DM and λ-CHT was enhanced by applying the mint extracts and riboflavin and a more significant degradation was achieved with UV-C than with either UV-A or sunlight, reaching a maximum decrement of the concentration by 67-76%. The light treatments did not significantly affect the in-vitro antioxidant activity of the natural antioxidants in cauliflower. A calculated dietary risk assessment revealed that obvious dietary health hazards of DM and λ-CHT pesticides when sprayed on cauliflower for pest control. The use of green chemical photosensitisers (mint extract and riboflavin) in combination with UV light irradiation represents a novel, sustainable, and safe approach to pesticide reduction in produce.
The contact toxicity of four insecticide formulations (deltamethrin, fipronil, fenitrothion, and imidacloprid) applied on three different substrates (tile, plywood, and concrete) against the adult rove beetle, Paederus fuscipes Curtis, was evaluated. The relative order of speed of killing effects was as follows: deltamethrin > imidacloprid > fipronil > fenitrothion. Although deltamethrin showed the fastest action against P. fuscipes, the recovery rate of rove beetles at 48 h posttreatment was moderate (approximately 25%) on the tile surface to high (approximately 80%) on the plywood surface. Thus, it is likely that the insects did not pick up the lethal dose especially on porous surfaces. In contrast, fipronil demonstrated delayed toxicity that might promote maximal uptake by the insects. More than 80% mortality was registered for tile and plywood surfaces up to 4 wk after exposure. High mortality (almost 100%) was recorded for imidacloprid-exposed P. fuscipes at 48 h posttreatment, but only on the tile surface. Among the four insecticides tested, fenitrothion was the least effective against P. fuscipes because low percentage to no mortality was recorded in the fenitrothion treatment.
The residual activity of herbicides may be detrimental to the environment, requiring analysis of the persistent residues in the soil and water. A field study was conducted to measure the residues of Imidazolinone (IMI) in three Clearfield® rice field soils at three different locations in Malaysia. The analyses of IMI in the soil samples were carried out using a high-performance liquid chromatography (HPLC). These herbicides are widely used; however, few studies have been conducted on both residues, especially in the context of Malaysian soil. Residues of imazapic and imazapyr were found to fall within 0.03-0.58 µg/mL and 0.03-1.96 µg/mL, respectively, in three locations. IMI herbicides are persistent in the soil, and their residues remain for up to 85 days after application. A pre-harvest study was suggested for these herbicides on water, which will provide a clearer indicator on the use of IMI in Clearfield® rice fields.
High amounts of insecticides are often used in intensive tropical vegetable production systems. Their persistence and residues in vegetables and soils need to be studied to ensure food safety and environmental stability. The dissipation of acephate, chlorpyrifos, cypermethrin and their metabolites was studied in green mustard [Brassica juncea (L.) Coss.] and soils. Two treatments, Impact 75 (acephate) and Agent 505 (cypermethrin plus chlorpyrifos), were applied 4 times at weekly intervals.
Preventive treatment with insecticides at high dosing rates before planting of a new crop- soil drenching- is a common practice in some tropical intensive cropping systems, which may increase the risk of leaching, soil functioning, and pesticide uptake in the next crop. The degradation rates and migration of acephate and chlorpyrifos and their primary metabolites, methamidophos and 3,5,6-trichloropyridinol (TCP), have been studied in clayey red yellow podzolic (Typic Paleudults), alluvial (Typic Udorthents), and red yellow podzolic soils (Typic Kandiudults) of Malaysia under field conditions. The initial concentrations of acephate and chlorpyrifos in topsoils were found to strongly depend on solar radiation. Both pesticides and their metabolites were detected in subsoils at the deepest sampling depth monitored (50 cm) and with maximum concentrations up to 2.3 mg kg(-1) at soil depths of 10 to 20 cm. Extraordinary high dissipation rates for weakly sorbed acephate was in part attributed to preferential flow which was activated due to the high moisture content of the soils, high precipitation and the presence of conducting macropores running from below the A horizons to at least 1 m, as seen from a dye tracer experiment. Transport of chlorpyrifos and TCP which both sorb strongly to soil organic matter was attributed to macropore transport with soil particles. The half-lives for acephate in topsoils were 0.4 to 2.6 d while substantially longer half-lives of between 12.6 and 19.8 d were observed for chlorpyrifos. The transport through preferential flow of strongly sorbed pesticides is of concern in the tropics.
A headspace solid-phase microextraction method has been developed for the determination of 8 pesticides in vegetables and fruits by using gas chromatography with an electron capture detector. Two types of fibers (polyacrylate, 85 microm and polydimethylsiloxane, 100 microm) have been assayed and compared. The main factors: extraction and desorption parameters, ionic strength, and the effects of dilution and organic solvents, were studied and optimized. The optimized procedures resulted in more than 80% recovery for all the investigated vegetable and fruit samples with RSD values below 10%.
Paddy fish (Trichogaster pectoralis Regan) were collected from five sampling locations in a major paddy-growing area of Malaysia and analysed for organochlorine residues. During the same period, ten farming families, chosen at random from each of the five sampling sites, were interviewed. Information was obtained about the quantity of paddy fish consumed, the amount and type of pesticide used on the paddy-field, and the frequency of application.The pesticide residues found in the fish samples were aldrin/dieldrin, chlordane, HCH, and DDT. Only the projected maximum intake level for aldrin/dieldrin approached the acceptable daily intake as recommended by FAO/WHO; other residue levels were relatively low. However, this study considered only fish; the total daily intake of pesticide residues by the Malaysian paddy farmer may be considerably increased by consumption of other contaminated food.
In the present study, the residual pesticide levels were determined in eggplants (Solanum melongena) (n = 16), purchased from four different markets in Dhaka, Bangladesh. The carbamate and organophosphorus pesticide residual levels were determined by high performance liquid chromatography (HPLC), and the efficiency of gamma radiation on pesticide removal in three different types of vegetables was also studied. Many (50%) of the samples contained pesticides, and three samples had residual levels above the maximum residue levels determined by the World Health Organisation. Three carbamates (carbaryl, carbofuran, and pirimicarb) and six organophosphates (phenthoate, diazinon, parathion, dimethoate, phosphamidon, and pirimiphos-methyl) were detected in eggplant samples; the highest carbofuran level detected was 1.86 mg/kg, while phenthoate was detected at 0.311 mg/kg. Gamma radiation decreased pesticide levels proportionately with increasing radiation doses. Diazinon, chlorpyrifos, and phosphamidon were reduced by 40-48%, 35-43%, and 30-45%, respectively, when a radiation strength of 0.5 kGy was utilized. However, when the radiation dose was increased to 1.0 kGy, the levels of the pesticides were reduced to 85-90%, 80-91%, and 90-95%, respectively. In summary, our study revealed that pesticide residues are present at high amounts in vegetable samples and that gamma radiation at 1.0 kGy can remove 80-95% of some pesticides.
A simple and sensitive analytical method has been developed employing gas chromatography coupled with electron capture detector (GC-ECD), and validated for screening and quantification of 15 pesticide residues at trace levels in cabbage, broccoli, cauliflower, lettuce, celery, spinach, and mustard. The method consists of two steps, first, to determine the significance of each factor by Pareto chart followed by optimization of these significant factors using central composite design (CCD). Minitab statistical software was used for these multivariate experiments for the generation of 2(4-1) design and CCD matrices. The method evaluation was done by external standard calibration with linearity range between 0.5 and 3mg/kg, with correlation coefficient 0.99, limit of detection (LOD) ranges between 0.02 and 4.5ng/g, and limit of quantification (LOQ) ranges between 0.2 and 45ng/g. The average recovery was between 60% and 128%, with RSD 0.2-19.8%. The method was applied on real vegetable samples from Cameron Highlands.
Occurrence and distribution of organochlorine pesticides (OCPs), organophosphate pesticides (OPPs), and pyrethroid pesticides (PYRs) residues in the leafy vegetables were analyzed together with the soil samples using gas chromatography-electron capture detector. Edible tissues of vegetables showed detectable residues of these compounds indicating the influence of the conventional farms and nearby organic farms. In the vegetables, the OCPs concentrations were recorded as nd-133.3 ng/g, OPPs as nd-200 ng/g, and PYRs as nd-33.3 ng/g. In the soil, the OCPs concentrations were recorded as nd-30.6 ng/g, OPPs as nd-26.6 ng/g, and for PYRs as nd-6.7 ng/g. Bioconcentration factor (BCF) was higher for the OPPs (0.3) than the OCPs and PYRs (1.1). The OCPs concentration in the vegetables decreased in the following order: spinach > celery > broccoli > cauliflower > cabbage > lettuce > mustard. For OPPs, the concentration decreased in the following order: cauliflower > spinach > celery > cabbage > broccoli > lettuce > mustard and for PYRs as spinach > celery > lettuce > cabbage > broccoli. Principal component analysis indicates that the sources of these pesticides are not the same, and the pesticide application on the vegetables depends on the type of crop. There is a significant positive correlation between OPPs and the soil (r = 0.65) as compared to OCPs and PYRs (r = 0.1) as the vegetables accumulated OPPs more efficiently than OCPs and PYRs.
Concern about environmental protection has increased over the years from a global viewpoint. To date, the percolation of pesticide waste into the groundwater tables and aquifer systems remains an aesthetic issue towards the public health and food chain interference. With the renaissance of activated carbon, there has been a consistent growing interest in this research field. Confirming the assertion, this paper presents a state of art review of pesticide agrochemical practice, its fundamental characteristics, background studies and environmental implications. Moreover, the key advance of activated carbon adsorption, its major challenges together with the future expectation are summarized and discussed. Conclusively, the expanding of activated carbon adsorption represents a plausible and powerful circumstance, leading to the superior improvement of environmental preservation.
Improved methods for extraction and clean up of fluroxypyr residue in water have been established. Two methods of fluroxypyr extraction were used, namely, Direct Measurement of fluroxypyr and Concentration of fluroxypyr onto A Solid Phase Extraction (SPE) Adsorbent, followed by elution with solvent before determination of fluroxypyr. The recovery for Direct Measurement of fluroxypyr in water containing 8-100 microg L(-1), ranged from 86 to 110% with relative standard deviation of 0.7 to 2.15%. For the second method, three types of SPE were used, viz. C18, C18 end-capped and polyvinyl dibenzene (ISOLUTE ENV+). The procedure involved concentrating the analyte from fluroxypyr-spiked water at pH 3, followed by elution of the analyte with 4 mL of acentonitrile. The recovery of fluroxypyr from the spiked sample at 1 to 50 microg L(-1) after eluting through either C18 or C18 end-capped ranged from 40-64% (with relative standard deviation of 0.7 to 2.15) and 41-65% (with standard deviation of 1.52 to 11.9). The use of ISOLUTE ENV+, gave better results than the C18, C18 end-capped or the Direct Measurement Methods. The recovery and standard deviation of fluroxypyr from spiked water using ISOLUTE ENV+ ranged from 91-102% and 2.5 to 5.3, respectively.
This study investigates pest management practices among lowland farmers on growing
leafy and fruit vegetables, particularly focusing on the pesticide usage in controlling pest. In
Malaysia, vegetable productions in lowland areas are to some extent really important as in the
highland areas due to the wide marketing channel, from local till traded across border. Yet, the
ignorance of vegetables safety regarding the appropriate of pesticide usage by farmers was
undeniable, as the market demands only products with good extrinsic quality. Thus a survey
was conducted among of 85 of lowland vegetable farmers to get information on their pest
management practices in farms. Result showed that the pesticide application by farmers on
vegetables crops still indicated a calendar spraying practices. In most cases, farmers tend to
harvest the vegetable products shortly after a few days of last pesticide spraying. In order to
enhance the food safety control starting from the primary production, extensive monitoring of
the current pesticide usage by farmers in vegetable productions is vital to provide an updated
data on the food safety risk regarding to the pesticide residues. Therefore, the thrust of this
paper was to get a better understanding on the level of safe pesticide usage among vegetables
farmers especially in areas of growing vegetables productions.