Utilizing Plackett-Burman design and response surface analysis to optimize ultrasonic cleaning of pesticide residues from rape.

BACKGROUND: Pesticide residues in fruits and vegetables threaten food safety. Cleaning before eating is a usual way to remove pesticide residues, so it is very important to find the most efficient cleaning conditions for public health. However, many previous cleaning studies only focused on a single variable which required a large amount of time manpower and material resources. Plackett-Burman design (PBD) and response surface methodology can avoid the earlier-mentioned problems and have potential in studying the influence and interaction of multiple factors. In this study, the effect of five factors on the removal of triadimefon and boscalid from rape by ultrasonic washing was evaluated through PBD: pH of water, ultrasonic cleaning time, water temperature, initial residual concentration and volume of water. RESULTS: Temperature had a significant effect on the rate of triadimefon removal while the other four factors impacted boscalid removal greatly. A higher temperature was better for the removal rate of triadimefon. Under alkaline environment, when initial residual concentration and cleaning time increased with decreasing water volume, the removal rate of boscalid increased. Furthermore, the interactions among factors were obtained. The regression coefficients of fitting equations about triadimefon and boscalid were 0.9657 and 0.9738, respectively. CONCLUSION: Changing pH of water, cleaning time, water volume and temperature during the washing process of rape through PBD designed experiments represents a valid strategy for improving the removal rate of two pesticides residue. This study provides a reference for ultrasonic cleaning conditions by a sink dishwasher, which has a positive effect on food safety. © 2021 Society of Chemical Industry.

Effect of storage states on stability of three organophosphorus insecticide residues on cowpea samples.

BACKGROUND: The stability of pesticide residues in stored samples is very important to ensure the quality of data about the residues. The evaluation of pesticide residues in food and environment samples is an important means to ensure food quality and protect consumers against potential dietary risks. Improper storage of pesticide residue samples may result in loss of pesticide and unreliable data, which could affect safety assessments. RESULTS: The influences of storage conditions, including temperature (-20 °C, 4 °C, and ambient temperature) and sample state (homogenized state and coarsely chopped state) on the storage stability of dichlorvos, malathion, and diazinon on cowpea were studied. Dichlorvos and malathion were more stable in an homogenized state than in a coarsely chopped state. At 4 °C, the residual dichlorvos in the coarsely chopped state and the homogenized state, respectively, was 12% and 69%; the residual malathion was 26% and 92%, respectively. Dichlorvos suffered a large loss of 89% and 59% for coarsely chopped and homogenized cowpea, even at -20 °C. It was obvious that the stability of dichlorvos and malathion were more affected by storage state than diazinon. The stability of diazinon was significantly affected by temperature. The effect of storage state and temperature on stability is likely to be correlated with enzymes in the matrix, such as superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD). CONCLUSION: The optimal stable storage conditions for three organophosphorus insecticides residues on cowpea were in the homogenized state and under a lower temperature. © 2021 Society of Chemical Industry.

More Than a First Flush: Urban Creek Storm Hydrographs Demonstrate Broad Contaminant Pollutographs.

Stormwater runoff clearly impacts water quality and ecological health of urban receiving waters. Subsequent management efforts are often guided by conceptual models of contaminant "first flushes", defined by disproportionate concentrations or mass loads early in the storm hydrograph. However, studies examining the dynamics of contaminant transport and receiving water hydrology have primarily focused on "traditional" stormwater contaminants and point sources, with less evaluation of chemically complex nonpoint pollution sources. Accordingly, we conducted baseflow and storm sampling in Miller Creek, a representative small, urban watershed in the Puget Sound region (WA, USA). We comprehensively characterized organic contaminant profiles and dynamics via targeted quantification of 35 stormwater-derived chemicals, complementary nontarget HRMS analyses, and surrogate chemical metrics of ecological health. For quantified analytes, total daily baseflow loads were 0.8-3.4 g/day and storm event loads were ∼80-320 g/storm (∼48 h interval), with nine contaminants detected during storms at >500 ng/L. Notably, urban creek "pollutographs" were much broader than relatively sharp storm hydrographs and exhibited transport-limited (rather than mass-limited) source dynamics, with immediate water quality degradation during low-intensity precipitation and continued mobilization of contaminant mass across the entire hydrograph. Study outcomes support prioritization of source identification and focused stormwater management efforts to improve water quality and promote ecosystem function in small urban receiving waters.

Improved analysis of propamocarb and cymoxanil for the investigation of residue behavior in two vegetables with different cultivation conditions.

BACKGROUND: A modified quick, easy, cheap, effective, rugged and safe (QuEChERS) method was developed for the simultaneous determination of highly water-soluble propamocarb and hydrophobic cymoxanil in potato tuber and tomato fruit. Residue behaviors of the fungicides in open field or greenhouse were investigated for the safety evaluation of these two pesticides, and the effects of cultivation conditions, fungicide exposure and fruit size of tomato on residue level are discussed. RESULTS: Vegetable samples were extracted with ammonia-acetonitrile, further purified with multiwall carbon nanotubes and analyzed using high-performance liquid chromatography tandem mass spectrometry. The method was validated with fortified samples at different concentration levels (0.05-2.0 mg kg-1 ). Average recoveries ranged from 84 to 111% with relative standard deviations between 0.3 and 5.5%. Limits of quantification (LOQs) were set at the lowest spiking level of 0.05 mg kg-1 . In tomato and cherry tomato, initial residue level of cymoxanil was below LOQ at recommended good agricultural practices. Propamocarb residues were affected by the cultivation conditions, with highest levels of 0.52 and 0.72 mg kg-1 in open field and greenhouse, respectively. In addition, residues of propamocarb in cherry tomatoes were found to be present at 1.25 mg kg-1 . CONCLUSIONS: The field trial results showed that propamocarb and cymoxanil residues in potato tubers were below LOQ due to the tubers not being exposed to sprayed pesticides. The unexpected high residue levels in cherry tomato seem to indicate that cherry tomato with small size presents certain accumulative effects of propamocarb. © 2020 Society of Chemical Industry.

Meptyldinocap and azoxystrobin residue behaviors in different ecosystems under open field conditions and distribution on processed cucumber.

BACKGROUND: Several diseases and insects may cause damage to the normal growth of cucumber. Azoxystrobin and meptyldinocap, because of their novel mode of action, are effective against pathogens that have developed reduced sensitivity to other fungicides. Azoxystrobin is persistent in various crops and environments. However, there is a lack of research on the dissipation of these two pesticides, especially meptyldinocap. RESULTS: Analytes could be quantified with decent recoveries of 90-101%, with relative standard deviations (RSDs) of 3.0-10.1%. The terminal residues of meptyldinocap and azoxystrobin in cucumber were all < limit of quantification (LOQ) (0.02 and 0.05 mg kg-1 ). The half-lives of meptyldinocap and azoxystrobin were 0.8-1.1 and 1.2-2.8 days, respectively. The processing factors (PFs) for washing were all < 1, but the removal rate for washing was < 29.0%. Peeling had a significant effect on the removal of pesticide. The largest residue reductions were noticed through the pickling process, but special care should be taken regarding residues in the pickling solution as pesticides could transfer to them from cucumber. A more interesting finding was that the degradation of two pesticides was accelerated by the addition of calcium oxide. CONCLUSION: Pesticide residues on cucumber decreased after these processes. These results enable the health-risks from dietary exposures to pesticide residues to be characterized. They enable maximum residue limits (MRLs) to be established for pesticide residues in food products. They also assist the optimization of food processing with regard to pesticide residue dissipation. © 2019 Society of Chemical Industry.

Residue behavior and removal of iprodione in garlic, green garlic, and garlic shoot.

BACKGROUND: Iprodione is considered to be an endocrine-disturbing pesticide, which could harm consumers. The garlic crop has three edible parts: the garlic, the green garlic, and the garlic shoot, which correspond to different stages of its growth. In this study, iprodione residue dissipation and distribution in these three edible parts were investigated, and dietary risk was evaluated. RESULTS: Iprodione residues were present in these samples in the following order: green garlic > garlic shoot > > garlic. The dissipation of iprodione in green garlic was slow with a half-life of 5.82-19.25 days. A very high RQchronic value of 207.35-407.30% suggested that the residual iprodione in green garlic had an unacceptable level of risk. Iprodione residue was significantly eliminated (59-90%) by an alkaline solution. The order for removing iprodione by soaking was the alkaline solutions (0.5% and 2% NaHCO3 ) > the acidic solutions (5% and 10% of vinegar) ≈ the neutral solutions (the 1% and 2% of table salt) > tap water. Processing factors (PFs) were <1, indicating that processing could decrease the iprodione residue level. CONCLUSION: This work could contribute to establishing maximum residue limits (MRLs) for iprodione in garlic, green garlic, and garlic shoots, and could provide guidance on the safe and appropriate use of iprodione in the garlic crop. © 2020 Society of Chemical Industry.

Quantification of organic contaminants in urban stormwater by isotope dilution and liquid chromatography-tandem mass spectrometry.

Pollutants transported in urban stormwater runoff induce pervasive water quality degradation in receiving waters. To accurately characterize stormwater quality and treatment system performance across the range of possible contaminant characteristics, comprehensive multi-residue analytical methods are necessary. Here, we developed a solid-phase extraction (SPE) and high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method to quantify representative stormwater-derived organic contaminants across multiple chemical classes, including vehicle-related chemicals, corrosion inhibitors, industrial chemicals, pesticides, pharmaceuticals and personal care products, and antioxidants. Extraction conditions, isotope-labeled internal standards, and LC-MS/MS parameters were optimized to enhance recovery, minimize matrix effects, and maximize selectivity and sensitivity. The developed method was sensitive (method quantification limits < 10 ng/L for > 80% of selected analytes) and accurate (mean relative recoveries in the range of 70-130%, with relative standard deviations < 25% for 77% of the analytes) for most of the analytes. The method was used to analyze samples collected from nine urban watersheds during a storm event; 62% of the 39 analytes were detected at least once at concentrations up to 540 ng/L (1,3-diphenylguanidine). Spatial trends in detection and concentration were observed for vehicle-related and industrial chemicals that correlated with vehicle traffic. Total concentrations of pesticides suggested that residential uses could be more important sources than agriculture. This study illustrates the pervasive occurrence of a wide variety of stormwater-derived chemicals in urban receiving waters and highlights the need to better understand their environmental fate and ecological implications. Graphical abstract.

Influence of lactic acid bacteria on stereoselective degradation of theta-cypermethrin.

The purpose of this study was to investigate the influence of four kinds of Lactic acid bacteria (LAB) on stereoselective degradation of theta-cypermethrin (CYP), including Lactobacillus plantarum, Lactobacillus casei, Lactobacillus delbrueckii, and Streptococcus thermophilus. An effective analytical method for (±)-theta-CYP in medium was developed by high-performance liquid chromatography with cellulose tris-(3,5-dimethylphenylcarbamate) chiral stationary phase. theta-Cypermethrin was spiked to LAB medium with different inoculation rates and sampled at 0, 2, 8, 24, 36, 48, 72, 120, 168, and 240 hours. The results showed that LAB influenced the half-lives and enantiomer fractions of theta-CYP enantiomers, which lead a closer degradation rate between the 2 stereoisomers, and no obvious difference was found among 4 LABs. Besides, the stereoselective degradation of theta-CYP was closely related to pH. The lower the pH (pH of 3, 5, 7, and 9), the lower the enantiomer fraction (from 4.88 to 6.69). At pH of 3, 7, and 9, significant differences of half-lives between enantiomers were observed. (-)-theta-Cypermethrin decreased faster than (+)-theta-CYP under pH of 3, while opposite results were indicated under pH of 7 and 9. Moreover, the acidic condition contributed to the higher chiral configuration stability of (±)-theta-CYP. (+)-Enantiomer was influenced by pH in a greater degree than (-)-enantiomer.

Binary-solvent-based ionic-liquid-assisted surfactant-enhanced emulsification microextraction for the determination of four fungicides in apple juice and apple vinegar.

A binary-solvent-based ionic-liquid-assisted surfactant-enhanced emulsification microextraction method was developed for the separation/preconcentration and determination of four fungicides (pyrimethanil, fludioxonil, cyprodynil, pyraclostrobin) in apple juice and apple vinegar. A nonchlorinated solvent amyl acetate, which has a lower density than water, was used as the extraction solvent, and an ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate, which has a high density and low toxicity, was used as a secondary solvent mixed with the extraction solvent. After centrifugation, the binary solvent drop with a relatively high density was deposited on the bottom of the tube. Some parameters influencing the extraction efficiency of analytes such as type of extraction solvent, ratio of ionic liquid, volume of mixed solvent, type and concentration of surfactant, sample pH, NaCl concentration, and vortex time were investigated and optimized. Under the optimized conditions, the proposed method provided a good linearity in the range of 5-200 µg/L. The limits of quantification of the method were in the range of 2-5 µg/L. The relative standard deviations for interday assays were 1.7-11.9%. The method was applied to the determination of pyrimethanil, fludioxonil, cyprodynil, and pyraclostrobin in apple juice and apple vinegar samples, and the accuracy was evaluated through recovery experiments.

Chronic and acute risk assessment of human exposed to novaluron-bifenthrin mixture in cabbage.

Based on the dissipation and residual level in cabbage determined by gas chromatography coupled with an electron capture detector (GC-ECD), chronic and acute risk assessments of the novaluron and bifenthrin were investigated. At different spiked levels, mean recoveries were between 81 and 108 % with relative standard deviations (RSDs) from 1.1 to 6.8 %. The limit of quantification (LOQ) was 0.01 mg kg(-1), and good linearity with correlation coefficient (>0.9997) were obtained. The half-lives of novaluron and bifenthrin in cabbage were in the range of 3.2~10 days. Based on the consumption data in China, the risk quotients (RQs) of novaluron and bifenthrin were all below 100 %. The chronic and acute risk of novaluron in cabbage was relatively low, while bifenthrin exerts higher acute risk to humans than chronic risk. The obtained results indicated that the use of novaluron-bifenthrin mixture does not seem to pose any chronic or acute risk to humans even if cabbages are consumed at high application dosages and short preharvest interval (PHI).

Ionic-liquid-based, manual-shaking- and ultrasound-assisted, surfactant-enhanced emulsification microextraction for the determination of three fungicide residues in juice samples.

A novel manual-shaking- and ultrasound-assisted surfactant-enhanced emulsification microextraction method was developed for the determination of three fungicides in juice samples. In this method, the ionic liquid, 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide, instead of a volatile organic solvent was used as the extraction solvent. The surfactant, NP-10, was used as an emulsifier to enhance the dispersion of the water-immiscible ionic liquid into an aqueous phase, which accelerated the mass transfer of the analytes. Organic dispersive solvent typically required in common dispersive liquid-liquid microextraction methods was not necessary. In addition, manual shaking for 15 s before ultrasound to preliminarily mix the extraction solvent and the aqueous sample could greatly shorten the time for dispersing the ionic liquid into aqueous solution by ultrasound irradiation. Several experimental parameters affecting the extraction efficiency, including type and volume of extraction solvent, type and concentration of surfactant, extraction time, and pH, were optimized. Under the optimized conditions, good linearity with the correlation coefficients (γ) higher than 0.9986 and high sensitivity with the limit of detection ranging from 0.4 to 1.6 µg/L were obtained. The average recoveries ranged from 61.4 to 86.0% for spiked juice, with relative standard deviations from 1.8 to 9.7%. The proposed method was demonstrated to be a simple, fast, and efficient method for the analysis of the target fungicides in juice samples.

Dissipation, terminal residues and risk assessment of fluopicolide and its metabolite in cucumber under field conditions.

In this study, the dissipation, terminal residue levels, and risk assessment of fluopicolide and its metabolite (2,6-dichlorobenzamide) in cucumber and soil under field conditions were investigated. An analytical method for the simultaneous quantification of fluopicolide and its metabolite in cucumber and soil using gas chromatography coupled with electron capture detection (GC-ECD) was developed. Recoveries were between 78 and 111%, with relative standard deviations (RSDs) from 1.6 to 10.2% at different spiked levels (0.01, 0.025, 0.5, and 2 mg kg(-1)). The limit of quantification (LOQ) was 0.01 mg kg(-1). Fluopicolide exhibited half-lives ranging from 2.0 to 3.3 days and 35 to 63 days, in cucumber and soil under field ecosystem, respectively. The results suggested that the degradation of fluopicolide to 2,6-dichlorobenzamide was quite limited. During harvest, the terminal residues of fluopicolide and its metabolite were both below 0.13 mg kg(-1), which were lower than the established temporary maximum residue limits (MRLs), 0.5 mg kg(-1). The risk quotients (RQs) ranged from 0.0033 to 0.0078, which showed low risk for different groups of people in China. The present study may provide guidance on reasonable use of this pesticide and serve as a reference for establishment official MRLs in China.

Multiresidue analysis of 16 pesticides in jujube using gas chromatography and mass spectrometry with multiwalled carbon nanotubes as a sorbent.

Although jujube is a minor crop and very few pesticides are registered on it, the application of pesticides during the growth stage of jujube is inevitable to control the pests or diseases. This situation has led to pesticide misuse. A modified quick, easy, cheap, effective, rugged, and safe method using a novel sorbent, multiwalled carbon nanotubes, as a dispersive solid-phase extraction sorbent combined with gas chromatography with mass spectrometry, was developed for the determination of 16 pesticides in jujube. Under the optimized conditions, recoveries of 76.7-112.4% were obtained for the target analytes at three spiked concentration levels. The relative standard deviations ranged from 1.2 to 12.3%. Limits of detection and limits of quantification for 16 pesticides ranged from 1 to 10 and 3 to 30 µg/kg, respectively. The residues of chlorpyrifos, hexaconazole, tebuconazole, and cyhalothrin were detected from samples obtained from the market.

Effervescence-assisted dispersive liquid-liquid microextraction using a solid effervescent agent as a novel dispersion technique for the analysis of fungicides in apple juice.

A novel effervescence-assisted dispersive liquid-liquid microextraction method has been developed for the determination of four fungicides in apple juice samples. In this method, a solid effervescent agent is added into samples to assist the dispersion of extraction solvent. The effervescent agent is environmentally friendly and only produces an increase in the ionic strength and a negligible variation in the pH value of the aqueous sample, which does not interfere with the extraction of the analytes. The parameters affecting the extraction efficiency were investigated including the composition of effervescent agent, effervescent agent amount, formulation of effervescent agent, adding mode of effervescent agent, type and volume of extraction solvent, and pH. Under optimized conditions, the method showed a good linearity within the range of 0.05-2 mg/L for pyrimethanil, fludioxonil, and cyprodinil, and 0.1-4 mg/L for kresoxim-methyl, with the correlation coefficients >0.998. The limits of detection for the method ranged between 0.005 and 0.01 mg/L. The recoveries of the target fungicides in apple juice samples were in the range of 72.4-110.8% with the relative standard deviations ranging from 1.2 to 6.8%.

Determination of strobilurin fungicides in cotton seed by combination of acetonitrile extraction and dispersive liquid-liquid microextraction coupled with gas chromatography.

The simultaneous determination of four strobilurin fungicides (picoxystrobin, kresoxim-methyl, trifloxystrobin, and azoxystrobin) in cotton seed by combining acetonitrile extraction and dispersive liquid-liquid microextraction was developed prior to GC with electron capture detection. Several factors, including the type and volume of the extraction and dispersive solvents, extraction condition and time, and salt addition, were optimized. The analytes were extracted with acetonitrile from cotton seed and the clean-up was carried out by primary secondary amine. Afterwards, 60 µL of n-hexane/toluene (1:1, v/v) with a lower density than water was mixed with 1 mL of the acetonitrile extract, then the mixture was injected into 7 mL of distilled water. A 0.1 mL pipette was used to collect a few microliters of n-hexane/toluene from the top of the aqueous solution. The enrichment factors of the analytes ranged from 36 to 67. The LODs were in the range of 0.1 × 10(-3) -2 × 10(-3) mg/kg. The relative recoveries varied from 87.7 to 95.2% with RSDs of 4.1-8.5% for the four fungicides. The good performance of the method, compared with the conventional pretreatments, has demonstrated it is suitable for determining low concentrations of strobilurin fungicide residues in cotton seed.

Determination of fungicides in fruit juice by ultrasound-assisted dispersive liquid-liquid microextraction based on solidification of floating organic solvent droplets followed by high performance liquid chromatography.

Ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) based on solidification of the floating organic solvent droplets (SFO) combined with HPLC was used for determination of five fungicides in fruit juice samples. 1-Dodecanol, which has a low density and low toxicity, was used as the extraction solvent in UA-DLLME. The solidification of floating organic droplets facilitates the transfer of analytes from the aqueous phase to the organic phase. This method was easy, quick, inexpensive, precise, and linear over a wide range. Under the optimized conditions, the enrichment factors for a 5 mL fruit juice sample were 25 to 56, and the LODs for the five fungicides ranged from 5 to 50 microg/L. The average recoveries ranged from 71.8 to 118.2% with RSDs of 0.9 to 13.9%. Application of the DLLME-SFO technique allows successful separation and preconcentration of the fungicides at a low concentration level in fruit juice samples.

Development and validation of an alternative to conventional pretreatment methods for residue analysis of butachlor in water, soil, and rice.

A rapid and effective alternative analytical method for residues of butachlor in water, soil, and rice was established. The operating variables affecting performance of this method, including different extraction conditions and cleanup adsorbents, were evaluated. The determination of butachlor residues in soil, straw, rice hull, and husked rice was performed using GC/MS after extraction with n-hexane and cleanup with graphite carbon black. The average recoveries ranged from 81.5 to 102.7%, with RSDs of 0.6-7.7% for all of the matrixes investigated. The limits of quantitation were 0.05 mg/kg in water and rice plant, and 0.01 mg/kg in soil, straw, rice hull, and husked rice. A comparison among this proposed method, the conventional liquid-liquid extraction, the Quick, Easy, Cheap, Effective, Rugged, and Safe method, and Soxhlet extraction indicated that this method was more suitable for analyzing butachlor in rice samples. The further validation of the proposed method was carried out by Soxhlet extraction for the determination of butachlor residues in the husked rice samples, and the residue results showed there was no obvious difference obtained from these two methods. Samples from a rice field were found to contain butachlor residues below the maximum residue limits set by China (0.5 mg/kg) and Japan (0.1 mg/kg). The proposed method has a strong potential for application in routine screening and processing of large numbers of samples. This study developed a more effective alternative to the conventional analytical methods for analyzing butachlor residues in various matrixes.

Adsorption of azoxystrobin and pyraclostrobin onto degradable and non-degradable microplastics: Performance and mechanism.

Microplastics (MPs) exist after agricultural operations and thus present potential hazards to the environment and human health. However, the ecological risks posed by MPs carrying pesticides remain unclear. In this study, the adsorption and desorption behaviors of two pesticides, azoxystrobin and pyraclostrobin, on degradable and non-degradable MPs of poly(butylene adipate-co-terephthalate) (PBAT) and polyethylene (PE) were compared before and after UV aging. Additionally, the bioaccessibility of MPs carrying pesticides within a condition simulating gastrointestinal fluids was evaluated. The results showed that, after UV aging, the adsorption capacity of PBAT for pesticides decreased, while that of PE increased. Moreover, PBAT possessed higher adsorption ability towards both the pesticides due to its higher specific surface area, pore volume, contact angle, and lower crystallinity, as well as stronger van der Waals forces, electrostatic interactions, and hydrogen bonding indicated by theoretical calculation. Bioaccessibility experiments showed that azoxystrobin and pyraclostrobin had a higher risk of desorption from PBAT than PE, which is mainly dependent on the LogKow of pesticides according to the random forest analysis. In brief, the study highlights the potential risks of degradable MPs carrying pesticides to human health and the ecosystem, especially when compared to their non-degradable counterparts, manifesting that the ecological risk posed by degradable MPs should not be ignored.

Substantial removal of four pesticide residues in three fruits with ozone microbubbles.

Developing a straightforward method to remove pesticide residues from fruits is essential for food safety. In this study, ozone microbubble treatment was performed on three fruits (strawberry, cherry, and apricot) to remove four pesticide residues (emamectin benzoate, azoxystrobin, boscalid, and difenoconazole) while comparing removal efficiency. The concentration of hydroxyl radicals in different washing orientations was homogeneous at a concentration ranging between 8.9 and 10.2 µmol·L-1. Under long washing time (18 min), strawberry, cherry, and apricot obtained higher removal rates of 51 %∼65 %, 51 %∼59 % and 24 %∼70 %, respectively. Moreover, scanning electron microscopy (SEM) and contact angle (CA) revealed that apricot has better hydrophobicity, leading to a higher pesticide removal of 45 âˆ¼ 84 % with less water and more vigorous washing. Notably, vitamin C content in fruits remain largely unchanged following ozone microbubble treatment. This study demonstrated the effectiveness of ozone microbubble treatment as pollution-free method for enhancing food safety by removing pesticide residues on fruits.

Comparison of different sample pre-treatments for multi-residue analysis of organochlorine and pyrethroid pesticides in chrysanthemum by gas chromatography with electron capture detection.

The widespread use of insecticides in Chinese herbal medicines has created a compelling need for the development of a multiresidue analytical method to help assure herbs safety. The operating variables affecting the performance of the multiresidue analysis of 34 organochlorine and 12 pyrethroid pesticides in chrysanthemum, a widely used kind of Chinese herbal medicines, were evaluated. Three different extraction solvents including n-hexane and its mixtures with acetone and petroleum ether were compared, and n-hexane was found to be an appropriate option. A combination of gel permeation chromatography and SPE was selected as the optimum cleanup, in comparison with dispersive SPE, or the two former methods alone. The determination of the 46 pesticide residues in the spiked chrysanthemum samples was performed by GC with electron capture detection. The average recoveries ranged from 71.3 to 102.6% with RSDs of 1.4-15.7% for all of the pesticides. The LOQs were in the range of 0.0015-0.2 mg/kg, while the LODs were between 0.0005 and 0.1 mg/kg. The satisfactory accuracy, and precision, in combination with a good separation and few interferences, have demonstrated the strong potential of this technique for its application in chrysanthemum analysis.