Liquid chromatography versus supercritical fluid chromatography coupled to mass spectrometry: a comparative study of performance for multiresidue analysis of pesticides.

Abundant studies have been published evaluating different parameters of reverse-phase liquid chromatography (LC) and supercritical fluid chromatography (SFC), both coupled to electrospray (ESI)/mass spectrometry (MS) for pesticide residue analysis. However, there is a lack of a comprehensive comparative study that facilitates deep knowledge about the benefits of using each technique. In the present study, the same mass spectrometer was used coupled to both liquid and supercritical fluid chromatographies with a multiresidue method of 215 compounds, for the analysis of pesticide residues in food samples. Through the injection of the spiked extracts, separate experiments were conducted. A study of the optimum ion source temperature using the different chromatography modes was performed. The results were evaluated in terms of sensitivity with tomato, leek, onion, and orange as representative fruit and vegetable matrices. The compounds which reported the highest area values in each chromatography were evaluated through their substance groups and polarity values. The impact of matrix effects obtained in tomato matrix was similar for both cases; however, SFC clearly showed better results in analyzing matrices with a higher number of natural co-extracted compounds. This can be explained by the combination of two effects: (i) chromatography separation and (ii) ion source efficiency. The chromatographic elution presented different profiles of matrix components, which had diverse impact on the coelution with the analytes, being more beneficial when SFC was used in the matrices studied. The data showed that the best results obtained in SFC are also related to a higher ionization efficiency even when the ESI emitter tip was not optimized for SFC flow. In the present study a comprehensive evaluation of the benefits and drawbacks of these chromatography modes for routine pesticide residue analysis related to target compounds/commodities is provided.

Case analysis of kinetics investigations in toxicity studies of pesticides to identify the nonlinearity of internal exposure and the influences of nonlinearity on the toxicological interpretation of pesticide residue.

The nonlinearity of internal exposure to 8 pesticides was investigated in toxicity studies using kinetics to identify nonlinearity visually and to investigate the influence of nonlinearity on toxicological evaluation. Data were obtained from risk assessment reports published by the Food Safety Commission (FSCJ). Nonlinearity was defined using 2 indicators: the lowest visual inflection point (LVIP) and the second lowest visual inflection point (SVIP) of kinetics by drawing a linear distribution chart. The area under the curve and 24-h urine concentrations were stable parameters used to identify the LVIP/SVIP. The sampling timing affected the blood concentrations, and the LVIP/SVIP was detected for 6 pesticides using the parent compounds or their metabolites as analytes. The subproportional nonlinearity was significant for these pesticides. The LVIP/SVIP values were consistent in the same species up to a 1-year period, but the values showed species-specific differences in several compounds. In all compounds found to be nonlinear, apical outcomes were observed at the SVIP or above. The presence of nonlinearity was recognized by the FSCJ. The recognition influenced their judgment of no-observed-adverse-effect levels (NOAELs) for carcinogenicity or health-based guidance values, indicating the importance of appropriate kinetics to identify the nonlinearity for toxicological evaluation of pesticide residue.

Evaluating the presence of pesticides in bananas: An integrative review.

INTRODUCTION: Pesticides are organic compounds widely used in modern agriculture, being relevant for helping plantations and increasing food production. The banana, a fruit with oriental origin, stands out for being widely produced in tropical and subtropical regions which, like other matrices, is susceptible to pest action. This review aims to evaluate the presence of pesticides in bananas according to Brazilian, European and Codex legislation. METHODS: Four databases, ScienceDirect, SciELO, PubMed and Springer, were used to find relevant articles in the literature addressing methods for the determination of pesticide residues in bananas using the terms "banana", "chromatography", "pesticides" and "determination". The search stages included reading abstracts and titles, reading the full text, extracting data and analyzing data from eligible articles. The search was restricted to original research articles published in English from 2008 to 2018. RESULTS: 404 articles were found from the initial research, with only 15 studies being considered eligible for this review. Mass spectrometry is the most widely used detection technique. 5 articles were seen to use a multiresidue method to analyze only bananas (pulp), and from these, only 2 studies used methods to analyze the pulp and peel. The articles analyzed 172 samples, with 59.3% of these being conducted in Europe, 32.5% being conducted in Asia and only 8.1% in South America. A total of 79.1%, 32.4% and 42.6% of samples were unsatisfactory according to the Brazilian, European and Codex legislation, respectively, with these samples being contaminated with pesticide residues. CONCLUSION: This review presents the scarcity of articles aimed at identifying pesticide residues in bananas and the urgency of checking the quality of the fruit that reaches the population. The MRLs allowed by different legislations have clear divergences that do not ensure the lowest concentration values that guarantee consumer safety.

Three approaches to minimize matrix effects in residue analysis of multiclass pesticides in dried complex matrices using gas chromatography tandem mass spectrometry.

This paper discusses one of the major concerns in pesticide residue analysis: the matrix effect related to gas chromatography (GC), which can adversely affect quantification. In this study, a comparison of approaches for dealing with the matrix effect was investigated for 236 pesticides in complex matrices, including dried herbs (Centaurea cyanus L., Matricaria chamomilla L., Thymus vulgaris L.) and dried fruit (currants, chokeberry), using a modified QuEChERS method and GC-MS/MS analysis. Three approaches were evaluated: (i) using matrix-matched calibration, (ii) adding a mixture of analyte protectants (APs) to every extract or (iii) injection prior to GC-MS/MS analysis. Finally, minimization of the matrix effect to the acceptable levels of -20 to 20% for over 80% of investigated pesticides was found when APs mixture was injected at the beginning of the sequence. In this approach, the matrix effects were significantly weaker for some pesticides than when matrix-matched calibration was used.

High-throughput analysis of pesticides in minor tropical fruits from Colombia.

In this work, a method has been applied and validated for the determination of a group of 35 multiclass pesticides in the minor tropical fruits rose apple/pomarrosa (Syzygium malaccense), starfruit/carambola (Averrhoa carambola), yoyomo (Spondias purpurea) and papayuela (Vasconcellea pubescens) cultivated and exported in Colombia. The AOAC 2007.1 QuEChERS method, that uses an acetic acid/acetate buffer, was applied together with gas chromatography coupled to a triple quadrupole mass spectrometer. The method was validated in terms of calibration, recovery at three levels of concentration and matrix effects (MEs). A mixture of analyte protectants was also used. A good linearity was obtained in all cases, while the study of the ME revealed the need of developing matrix-matched calibration for many pesticides. Recovery values were in the range 70-120% with relative standard deviation values less than 20% for most of the pesticides studied. The lowest calibration level was 5 µg/kg. Several samples of each type were analysed.

A health-based regulatory chain framework to evaluate international pesticide groundwater regulations integrating soil and drinking water standards.

Pesticide residues in groundwater, mainly transported from contaminated soil, may threaten drinking water sources and cause adverse health effects. Therefore, pesticide groundwater standards were implemented by international environmental agencies to ensure the quality of groundwater, which serves as the direct drinking water source in many countries. However, regulatory inconsistencies are always found among groundwater, soil, drinking water, and even health standards due to the lack of communication among the regulatory processes. This study first developed a health-based regulatory chain framework to analyze pesticide groundwater regulations integrating soil, drinking water, and health regulations. Six regulatory indexes associated with probabilistic risk assessments and pesticide transport modeling were constructed to evaluate the performance of pesticide groundwater regulations identified from 56 countries. Worldwide pesticide groundwater regulations were analyzed by quantifying the impact on the downstream (exposure pathways in general) pesticide drinking water standards and human health and the influence from upstream (environmental pathways in general) soil regulations. The results indicated that in general, worldwide pesticide soil regulations do not encompass a sufficient number of pesticides or provide appropriate standard values to be compatible with groundwater regulations. The computed indexes between pesticide groundwater and drinking water regulations indicated more positive results than soil regulations because most European nations have groundwater regulations that are compatible with those of drinking water. However, most pesticide groundwater regulations could not protect human health according to the health-based indexes. Hopefully, the regulatory framework developed in this study will help environmental agencies comprehensively evaluate and establish pesticide groundwater regulations.

Pesticide Use, Poisoning, and Knowledge and Unsafe Occupational Practices in Thailand.

The agricultural system in Thailand has shifted from a traditional to a commercial agricultural system. Pesticides have been imported into Thailand to increase agricultural productivity, resulting in adverse health effects for farmers and consumers. However, the scientific data available in Thailand are limited and inconsistent. Thus, this article reviews research studies regarding pesticide use, poisoning, and knowledge and unsafe occupational practices in Thailand over the last decade. This article also makes recommendations for future policies. Research studies conducted in Thailand during 2006-2017 were reviewed and summarized. Overall, there are several solutions to address the pesticide problem, such as rigorous legislation and regulations, campaigns for reducing pesticide use, education, and training. The Thai government has an important role in making policies and regulations and encouraging all agricultural activities to be sustainable.

Method development, matrix effect, and risk assessment of 49 multiclass pesticides in kiwifruit using liquid chromatography coupled to tandem mass spectrometry.

In the present study, a liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method with a minimal matrix effect (ME) was developed and validated for simultaneous determination of a diverse range of pesticides (49) in kiwifruit. Samples extracted by the quick, easy, cheap, effective, rugged, and safe (QuEChERS) citrate-buffered method were analyzed either without purification or following purification (with primary secondary amine (PSA) or PSA + graphitized carbon black (GCB)). With the addition of a clean-up step, the suppression of the ME decreased, with a higher number of pesticides determined by the application of PSA + GCB. The method exhibited good linearity with coefficients of determination (R2) ≥ 0.9972 and satisfactory recoveries (70-120%) with a relative standard deviations (RSDs) <10%. The limits of quantification (LOQ) were lower than the maximum residue limits (MRLs) set by the Korean Ministry of Food and Drug Safety (MFDS) and the CODEX Alimentarius. The developed method was applied to the real samples and the results indicated that the quantitated levels of all pesticides, except for pyraclostrobin and carbendazim, are lower than the MRLs set by the regulatory authorities. The percentage of the acceptable daily intake was <20%, suggesting that there is no risk associated with the intake of residual pesticides through kiwifruit.

Monitoring pesticide residues in dates marketed in Al-Qassim, Saudi Arabia using a QuEChERS methodology and liquid chromatography-tandem mass spectrometry.

A sensitive, simple and rapid QuEChERS extraction method and liquid chromatography equipped with triple quadrupole mass spectrometry (LC-MS/MS) were used to determine 42 pesticides in dates. Acidified acetonitrile and citrate buffer salts were used to extract re-hydrated samples. Acceptable validation performances were achieved, i.e. recovery range of 70-120% and RSD values ≤20% for 42 analytes at three different concentrations:100, 50 and 10 µg/kg. This method was used to analyse 200 date fruit samples (var. Sukkari) collected from different large markets in the Al-Qassim region in Saudi Arabia. Pesticide residues were detected in 36 (18%) of the date fruits samples, and 15 samples (7.5%) exceeded the maximum residue levels. The ruggedness test results showed that this method is robust and suitable for the determination of pesticide residues in dates. Additionally, the results showed that the monitored dates did not have a health impact on consumers in Saudi Arabia during the study period.

Residue analysis and risk assessment of pyrethrins in open field and greenhouse turnips.

A sensitive and selective method was developed and validated for the determination of pyrethrin residues in turnips (turnip leaves, turnip tubers, and the whole of plant) and cultivated soil using gas chromatography coupled with mass spectrometry (GC-MS). Six major components of pyrethrins (pyrethrin I and II, cinerin I and II, and jasmolin I and II) were separated and identified. The method involving solid-phase extraction (SPE) cleanup led to satisfactory average recoveries (88.1-104%) with limits of quantification (LOQs) of 0.05 mg/kg. The dissipation and final residue of pyrethrins in six provinces (among these places, two experiments were conducted in greenhouse and other four experiments in open filed) in China were studied. The trial results suggested that the half-lives of pyrethrins in the whole of turnips and soil were 0.5-1.6 and 1.0-1.3 days, respectively, and the degradation of pyrethrins in the greenhouse was quicker than that in open fields. The final residues of pyrethrins in turnip leaves and tubers were all below the maximum residue limit (MRL) established by the EU (1.0 mg/kg). A pre-harvest interval of 2 days and MRL of 1.0 mg/kg are recommended to ensure food safety standards for pyrethrins in turnips. Long-term risk assessment and short-term risk assessment of turnip tubers were evaluated. Hazard quotient (HQ) and acute hazard index (aHI) were significantly less than 100%, indicating negligible risk for consumption of turnip tubers.

Food and feed chemical contaminants in the European Union: Regulatory, scientific, and technical issues concerning chemical contaminants occurrence, risk assessment, and risk management in the European Union.

A priority of the European Union is the control of risks possibly associated with chemical contaminants in food and undesirable substances in feed. Following an initial chapter describing the main contaminants detected in food and undesirable substances in feed in the EU, their main sources and the factors which affect their occurrence, the present review focuses on the "continous call for data" procedure that is a very effective system in place at EFSA to make possible the exposure assessment of specific contaminants and undesirable substances. Risk assessment of contaminants in food atances in feed is carried currently in the European Union by the CONTAM Panel of EFSA according to well defined methodologies and in collaboration with competent international organizations and with Member States.

Food safety in Thailand. 3: Pesticide residues detected in mangosteen (Garcinia mangostana L.), queen of fruits.

BACKGROUND: For developing countries like Thailand, regulation of pesticide usage exists, but it is not fully enforced. Therefore, pesticide residues in vegetables and fruits have not been well monitored. This study aimed to determine the pesticide residues in mangosteen fruits sold in Thailand. The mangosteen samples (n = 111) were purchased and the contents of 28 pesticides were analysed by GC-MS/MS method. RESULTS: Of the pesticides tested, eight were found in 100% of the mangosteen samples. However, in 97% of these samples, either chlorothalonil, chlorpyrifos, diazinon, dimethoate, metalaxyl or profenofos was detected exceeding their maximum residue limits (MRLs), representing a 97% rate of pesticide detection above the MRL. This rate is much higher than those found in other fruits sold in developed countries. However, this conclusion excludes the fresh Thai mangosteens grown for export, as these are generally cultivated and harvested to GAP standards. Since the edible part of the mangosteen is the pulp, washing the fruits with running water can reduce the risk of pesticide residues contaminating the pulp which would be eaten by the consumer. CONCLUSION: The findings strongly suggest that routine monitoring of pesticide residues in fruits and vegetables is required to reduce the health risks associated with consuming contaminated food. © 2016 Society of Chemical Industry.

Dilution standard addition calibration: A practical calibration strategy for multiresidue organic compounds determination.

Among calibration approaches for organic compounds determination in complex matrices, external calibration, based in solutions of the analytes in solvent or in blank matrix extracts, is the most applied approach. Although matrix matched calibration (MMC) can compensates the matrix effects, it does not compensate low recovery results. In this way, standard addition (SA) and procedural standard calibration (PSC) are usual alternatives, despite they generate more sample and/or matrix blanks consumption need, extra sample preparations and higher time and costs. Thus, the goal of this work was to establish a fast and efficient calibration approach, the diluted standard addition calibration (DSAC), based on successive dilutions of a spiked blank sample. In order to evaluate the proposed approach, solvent calibration (SC), MMC, PSC and DSAC were applied to evaluate recovery results of grape blank samples spiked with 66 pesticides. Samples were extracted with the acetate QuEChERS method and the compounds determined by ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). Results indicated that low recovery results for some pesticides were compensated by both PSC and DSAC approaches. Considering recoveries from 70 to 120% with RSD <20% as adequate, DSAC presented 83%, 98% and 100% of compounds meeting this criteria for the spiking levels 10, 50 and 100µgkg(-1), respectively. PSC presented same results (83%, 98% and 100%), better than those obtained by MMC (79%, 95% and 97%) and by SC (62%, 70% and 79%). The DSAC strategy showed to be suitable for calibration of multiresidue determination methods, producing adequate results in terms of trueness and is easier and faster to perform than other approaches.

Proposal for field-based definition of soil bound pesticide residues.

The environmental significance of soil bound pesticide residues (SBPR) is potentially large because approximately one third of the applied mass of the pesticides in agriculture ends up as SBPR. At EU level, there is little regulatory guidance available on the environmental risk assessment of SBPR in spite of some 50 years of SBPR research. This lack of guidance is partially caused by the fact that the current definitions of SBPR are founded on non-extractability in soil in the laboratory whereas for the environmental risk assessment not the soil in the laboratory but the soil in the field is the system of interest. Therefore a definition of SBPR is proposed that is based on the field soil: a molecule (further called 'the mother molecule') is soil bound if a relevant part of this molecule has become part of the solid phase in the soil and if this relevant part will never be released again to the liquid phase in soil under relevant field conditions in the form of this mother molecule or in the form of another molecule that may possibly raise environmental or human toxicological concerns. This mother molecule may be the parent substance that is applied to the soil but it may also be a metabolite of this parent substance. A consequence of the definition is that the SBPR terminology becomes more precise because the mother molecule of the soil bound residue has to be specified. A further consequence is that very strong but reversible sorption of molecules such as paraquat is not considered soil-bound residue anymore (as may be demonstrated by a self-exchange extraction procedure). Furthermore, the definition requires that risk managers have to define what they consider as 'relevant field conditions' (e.g. include also changes of agricultural fields into forests?).

Potential toxic effects of glyphosate and its commercial formulations below regulatory limits.

Glyphosate-based herbicides (GlyBH), including Roundup, are the most widely used pesticides worldwide. Their uses have increased exponentially since their introduction on the market. Residue levels in food or water, as well as human exposures, are escalating. We have reviewed the toxic effects of GlyBH measured below regulatory limits by evaluating the published literature and regulatory reports. We reveal a coherent body of evidence indicating that GlyBH could be toxic below the regulatory lowest observed adverse effect level for chronic toxic effects. It includes teratogenic, tumorigenic and hepatorenal effects. They could be explained by endocrine disruption and oxidative stress, causing metabolic alterations, depending on dose and exposure time. Some effects were detected in the range of the recommended acceptable daily intake. Toxic effects of commercial formulations can also be explained by GlyBH adjuvants, which have their own toxicity, but also enhance glyphosate toxicity. These challenge the assumption of safety of GlyBH at the levels at which they contaminate food and the environment, albeit these levels may fall below regulatory thresholds. Neurodevelopmental, reproductive, and transgenerational effects of GlyBH must be revisited, since a growing body of knowledge suggests the predominance of endocrine disrupting mechanisms caused by environmentally relevant levels of exposure.

Integrated pest management of "Golden Delicious" apples.

Monitoring of plant protection product (PPP) residues in "Golden Delicious" apples was performed in 2011-2013, where 216 active substances were analysed with three analytical methods. Integrated pest management (IPM) production and improved IPM production were compared. Results were in favour of improved IPM production. Some active compounds determined in IPM production (boscalid, pyraclostrobin, thiacloprid and thiametoxam) were not found in improved IPM production. Besides that, in 2011 and 2012, captan residues were lower in improved IPM production. Risk assessment was also performed. Chronic exposure of consumers was low in general, but showed no major differences for IPM and improved IPM production for active substances determined in both types of production. Analytical results were compared with the European Union report of 2010 where 1.3% of apple samples exceeded maximum residue levels (MRLs), while MRL exceedances were not observed in this survey.

Use of Combined Uncertainty of Pesticide Residue Results for Testing Compliance with Maximum Residue Limits (MRLs).

The uncertainty of pesticide residue levels in crops due to sampling, estimated for 106 individual crops and 24 crop groups from residue data obtained from supervised trials, was adjusted with a factor of 1.3 to accommodate the larger variability of residues under normal field conditions. Further adjustment may be necessary in the case of mixed lots. The combined uncertainty of residue data including the contribution of sampling is used for calculation of an action limit, which should not be exceeded when compliance with maximum residue limits is certified as part of premarketing self-control programs. On the contrary, for testing compliance of marketed commodities the residues measured in composite samples should be greater than or equal to the decision limit calculated only from the combined uncertainty of the laboratory phase of the residue determination. The options of minimizing the combined uncertainty of measured residues are discussed. The principles described are also applicable to other chemical contaminants.

The presence and management of contaminants in non-certified, agriculturally sourced food items used as enrichment for laboratory animals.

One enrichment strategy for laboratory animals is the provision of food variety and foraging opportunities. Fresh agricultural items, including produce or packaged human food items, provide variation in palatability, texture and complexity and can therefore be used as enrichment for lab animals. But concerns are often raised that these food items might sometimes carry contaminants that could affect research subjects and confound experimental results. The author discusses the potential for agriculturally sourced foods used as enrichment for lab animals to be contaminated with mycotoxins, microorganisms and pesticide residues and the effects these contaminants might have on lab animals. He also suggests strategies for reducing the risk of contamination.

Development of a new cucumber reference material for pesticide residue analysis: feasibility study for material processing, homogeneity and stability assessment.

The feasibility of the production of a reference material for pesticide residue analysis in a cucumber matrix was investigated. Cucumber was spiked at 0.075 mg/kg with each of the 15 selected pesticides (acetamiprid, azoxystrobin, carbendazim, chlorpyrifos, cypermethrin, diazinon, (α + ß)-endosulfan, fenitrothion, imazalil, imidacloprid, iprodione, malathion, methomyl, tebuconazole and thiabendazole) respectively. Three different strategies were considered for processing the material, based on the physicochemical properties of the vegetable and the target pesticides. As a result, a frozen spiked slurry of fresh cucumber, a spiked freeze-dried cucumber powder and a freeze-dried cucumber powder spiked by spraying the powder were studied. The effects of processing and aspects related to the reconstitution of the material were evaluated by monitoring the pesticide levels in the three materials. Two separate analytical methods based on LC-MS/MS and GC-MS/MS were developed and validated in-house. The spiked freeze-dried cucumber powder was selected as the most feasible material and more exhaustive studies on homogeneity and stability of the pesticide residues in the matrix were carried out. The results suggested that the between-unit homogeneity was satisfactory with a sample intake of dried material as low as 0.1 g. A 9-week isochronous stability study was undertaken at -20 °C, 4 °C and 18 °C, with -70 °C designated as the reference temperature. The pesticides tested exhibited adequate stability at -20 °C during the 9-week period as well as at -70 °C for a period of 18 months. These results constitute a good basis for the development of a new candidate reference material for selected pesticides in a cucumber matrix.

[Risk assessment and countermeasures of BTEX contamination in soils of typical pesticide factory].

Soil samples around three representative pesticide factories were collected in Zhangjiakou City, Hebei Province, and analyzed to identify their pollution characteristics and health risk of BTEX by purge-and trap and gas chromatography/mass spectroscopy method. Total concentrations of BTEX in soils in Plant A, B and C ranged from 673.50 to 32 363.50 ng x g(-1), nd to 6 461.80 ng x g(-1) and 461.70 to 8 740.80 ng x g(-1), respectively. Concentrations of detected toluene (4 619.50-7 234.30 ng x g(-1)) and ethylbenzene (364.60-7 944.60 ng x g(-1)) had exceeded the Canadian guidelines for industrial land (370 ng x g(-1) and 82 ng x g(-1)), and concentration of xylene (19 799.40 ng x g(-1)) in dust in production area of Plant A was larger than the Dutch soil intervention value (17 000 ng x g(-1)). While concentrationsn of BTEX around Plant A (Region I ) and Plant B and C (Region II) ranged from nd to 645.81 ng x g(-1), and nd to 309.13 ng x g(-1), respectively, which were below the Canadian guidelines for agricultural land. The non-carcinogenic risk of BTEX in Plant A (2.90E-06 -1.32E-04), B (nd -4.30E-05) and C (1.29E-06 -5.64E-05) were all below 1, which suggested that no obvious health risk existed in each plant. The non-carcinogenic risks in Region I (nd -2.02E-06) and Region II (nd -1.10E-06) were below than 1, and also lower than those in factories. High risk areas were mainly concentrated in the downwind, moreover, soils around villages and towns were also with higher risk. In conclusion, soils and dusts in each factory had been polluted and the quality of agricultural land had been partly deteriorated. Finally, environmental management and occupational protection countermeasures were proposed based on the research results.