Development of a simple extraction and clean-up procedure for determination of organochlorine pesticides in soil using gas chromatography–tandem mass spectrometry

Incorporation of Cu-TATAB metal-organic framework within polyurethane nanocomposite for enhanced thin film microextraction of some chlorinated pesticides

In this research, electrospun nanofibers based on copper-based metal organic framework (MOF)/polyurethane (PU) were prepared in order to achieve an applicable and superior extractive phase. The incorporation of MOF, in the synthesized nanocomposite contributed to the enhanced sorption efficiency. The prepared sorbent was implemented for the thin film microextraction (TFME) of target compounds with subsequent quantification using gas chromatography-mass spectrometry (GC-MS). To obtain the maximum efficiency of the synthesized sorbent, the influential parameters on extraction and desorption steps, including the MOF percentage in nanocomposite, desorption solvent type and its volume, desorption time, solution ionic strength and extraction time were optimized. After method development, the linear dynamic range (0.02-700 μg L-1), limits of detection (LODs) (0.005-0.1 μg L-1) and limits of quantification (LOQs))0.02-0.33 μg L-1(were calculated. The relative standard deviations values for intra-day and inter-day analysis were found to be in the range of 4.3-5.3 % and 6.2-8.1 %, respectively. The developed method was validated for the TFME of model organochlorine (OC) pesticide residues in fish, soil and water samples. the recovery values for the spiked samples at two concentration levels of 5 and 100 µg l-1 were found in the range of 72-110 %.

A method for evaluating the effects of gentle remediation options (GRO) on soil health: Demonstration at a DDX-contaminated tree nursery in Sweden

Healthy soils provide valuable ecosystem services (ES), but soil contamination can inhibit essential soil functions (SF) and pose risks to human health and the environment. A key advantage of using gentle remediation options (GRO) is the potential for multifunctionality: to both manage risks and improve soil functionality. In this study, an accessible, scientific method for soil health assessment directed towards practitioners and decision-makers in contaminated land management was developed and demonstrated for a field experiment at a DDX-contaminated tree nursery site in Sweden to evaluate the relative effects of GRO on soil health (i.e., the 'current capacity' to provide ES). For the set of relevant soil quality indicators (SQI) selected using a simplified logical sieve, GRO treatment was observed to have highly significant effects on many SQI according to statistical analysis due to the strong influence of biochar amendment on the sandy soil and positive effects of nitrogen-fixing leguminous plants. The SQI were grouped within five SF and the relative effects on soil health were evaluated compared to a reference state (experimental control) by calculating quantitative treated-SF indices. Multiple GRO treatments are shown to have statistically significant positive effects on many SF, including pollutant attenuation and degradation, water cycling and storage, nutrient cycling and provisioning, and soil structure and maintenance. The SF were in turn linked to soil-based ES to calculate treated-ES indices and an overall soil health index (SHI), which can provide simplified yet valuable information to decision-makers regarding the effectiveness of GRO. The experimental GRO treatment of the legume mix with biochar amendment and grass mix with biochar amendment are shown to result in statistically significant improvements to soil health, with overall SHI values of 141 % and 128 %, respectively, compared to the reference state of the grass mix without biochar (set to 100 %).

Development of simplified probabilistic models for predicting phytoextraction timeframes of soil contaminants: demonstration at the DDX-contaminated Kolleberga tree nursery in Sweden

Phytoextraction, utilizing plants to remove soil contaminants, is a promising approach for environmental remediation but its application is often limited due to the long time requirements. This study aims to develop simplified and user-friendly probabilistic models to estimate the time required for phytoextraction of contaminants while considering uncertainties. More specifically we: i) developed probabilistic models for time estimation, ii) applied these models using site-specific data from a field experiment testing pumpkin (Cucurbita pepo ssp. pepo cv. Howden) for phytoextraction of DDT and its metabolites (ΣDDX), iii) compared timeframes derived from site-specific data with literature-derived estimates, and iv) investigated model sensitivity and uncertainties through various modelling scenarios. The models indicate that phytoextraction with pumpkin to reduce the initial total concentration of ΣDDX in the soil (10 mg/kg dw) to acceptable levels (1 mg/kg dw) at the test site is infeasible within a reasonable timeframe, with time estimates ranging from 48-123 years based on literature data or 3 570-9 120 years with site-specific data using the linear or first-order exponential model, respectively. Our results suggest that phytoextraction may only be feasible at lower initial ΣDDX concentrations (< 5 mg/kg dw) for soil polishing and that alternative phytomanagement strategies should be considered for this test site to manage the bioavailable fraction of DDX in the soil. The simplified modes presented can be useful tools in the communication with site owners and stakeholders about time approximations for planning phytoextraction interventions, thereby improving the decision basis for phytomanagement of contaminated sites.

Bioaccumulation of pollutants in the green-lipped mussel Perna viridis: Assessing pollution abatement in Victoria Harbour and its adjacent aquaculture area, Hong Kong, and the minimal human health risks from mussel consumption

The green-lipped mussel Perna viridis was utilised for pollution biomonitoring in Victoria Harbour and its adjacent aquaculture area in Hong Kong. P. viridis was collected from a reference site and redeployed at five study sites for five weeks during the dry and wet seasons of 2019. Our study found various polycyclic aromatic hydrocarbons (PAHs) and heavy metals in the mussel tissue, while polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were not detected. P. viridis at the reference site generally displayed lower levels of pollutants. Comparing with previous research in the 1980s and 2000s, we observed substantial reduction in the tissue levels of PAHs, PCBs, OCPs and heavy metals in P. viridis. The human health risks associated with consuming these mussels were determined to be insignificant. Our findings imply that the Harbour Area Treatment Scheme has been effective in improving the water quality in Victoria Harbour and its adjacent aquaculture area.

A magnetic molecularly imprinted polymer based on an eco-friendly deep eutectic solvent for the selective recognition of dichlorodiphenyl trichloroethane and its degradation products in fruits and vegetables

A new magnetic molecularly imprinted polymer was successfully synthesized using a ternary deep eutectic solvent derived from caffeic acid-choline chloride-formic acid as a functional monomer, thymol-menthol deep eutectic solvent as a template, ethylene glycol dimethacrylate as a cross-linker, potassium peroxodisulfate as an initiator, and aqueous ethanol solution (90% (v/v)) as a porogen. The synthesized material was characterized and applied for magnetic solid-phase extraction of dichlorodiphenyl trichloroethane and its degradation products. Optimization of the extraction condition was carried out using the central composite design and response surface methodology. The good analytical performance of magnetic solid phase extraction/gas chromatography‒mass spectrometry using the proposed adsorbent shows a wide linear range of 0.07-500 ng g-1 with R2 greater than 0.992. Low detection limits and quantitation limits were observed in the ranges of 0.01-2.00 ng g-1 and 0.07-2.50 ng g-1, respectively. The precisions shown in terms of relative standard deviations were lower than 7.0% for intraday (n=5) and 8.6% for interday (n=5 × 3) experiments. The proposed method was applied for preconcentration and determination of dichlorodiphenyl trichloroethane and its degradation products in fruit and vegetable samples. The satisfactory recoveries of the real samples at three spiked concentrations were obtained in the range of 79.1%-110.9% with RSDs lower than 7.5%. The findings highlight the importance of developing efficient sorbents for the enrichment of persistent organic pollutants in food matrices.

Hyperspeed method for analyzing organochloride pesticides in sediments using two-dimensional gas chromatography–time-of-flight mass spectrometry

Pesticides are traditionally analyzed using conventional gas chromatography. When fast chromatography is associated with comprehensive two-dimensional gas chromatography (GC × GC), the resulting method presents high-resolution separation associated with a higher chromatographic speed. In the present work, a method for pesticide analysis in sediment samples was developed using quick, easy, cheap, effective, rugged, and safe extraction (QuEChERS) and a hyperspeed GC × GC separation. The QuEChERS procedure reported in the literature was extended to incorporate the analytes tetrachloro-m-xylene, decachlorobiphenyl, trans-chlordane, chlordane, endosulfan lactone, and endosulfan ether. To understand the chromatographic method improvement achieved, the recent concept of average theoretical peak time (ATPT) was used. The ATPT improved from that of the traditional GC × GC separation to the proposed method, and the separation speed can be classified as a hyperspeed separation. The limit of detection and quantitation of the compounds in the standard mix ranged from 0.39 to 17.96 µg L^-1 and 1.18 to 54.43 µg L^-1, respectively. The method showed acceptable RSD% (relative standard deviation) values and little interference of the sediment matrix in the extraction procedure. The developed method was applied to the determination of a mixture of 19 compounds in 16 sediment samples from the Pirapetinga River and Paraíba do Sul River in Brazil.

Pesticide-Residue Analysis in Soils by the QuEChERS Method: A Review

Pesticides are among the most important contaminants worldwide due to their wide use, persistence, and toxicity. Their presence in soils is not only important from an environmental point of view, but also for food safety issues, since such residues can migrate from soils to food. However, soils are extremely complex matrices, which present a challenge to any analytical chemist, since the extraction of a wide range of compounds with diverse physicochemical properties, such as pesticides, at trace levels is not an easy task. In this context, the QuEChERS method (standing for quick, easy, cheap, effective, rugged, and safe) has become one of the most green and sustainable alternatives in this field due to its inherent advantages, such as fast sample preparation, the minimal use of hazardous reagents and solvents, simplicity, and low cost. This review is aimed at providing a critical revision of the most relevant modifications of the QuEChERS method (including the extraction and clean-up steps of the method) for pesticide-residue analysis in soils.

Methods for the analysis of endocrine disrupting chemicals in selected environmental matrixes

Endocrine disrupting chemicals (EDCs) are heterogenous in structure, chemical and physical properties, and their capacity to partition into various environmental matrixes. In many cases, these chemicals can disrupt the endocrine systems of vertebrate and invertebrate organisms when present at very low concentrations. Therefore, sensitive and varied analytical methods are required to detect these compounds in the environment. This review summarizes the analytical methods and instruments that are most used to monitor for EDCs in selected environmental matrixes. Only those matrixes for which there is a clear link between exposures and endocrine effects are included in this review. Also discussed are emerging methods for sample preparation and advanced analytical instruments that provide greater selectivity and sensitivity.

Impact of chemical elements released by the volcanic eruption of La Palma (Canary Islands, Spain) on banana agriculture and European consumers

The recent volcanic eruption on the island of La Palma has aroused the concern of banana producers and consumers, given that in its area of influence there are thousands of hectares of banana plantations with an annual production of about 100 million kilos for export. Since volcanoes are one of the main natural sources of heavy metal contamination, we sampled bananas from the affected area and determined the concentrations of 50 elements (Ag, Al, As, Au, Ba, Be, Bi, Cd, Ce, Co, Cr, Cu, Cu, Dy, Er, Eu, Fe, Ga, Gd, Hg, Ho, In, La, Lu, Mn, Mo, Nb, Nd, Ni, Os, Pb, Pd, Pm, Pr, Pt, Sb, Sc, Se, Sm, Sn, Sr, Ta, Tb, Th, Ti, Tl, Tm, U, Y, Yb and Zn). The levels of 36 elements were elevated but the washing implemented after the eruption can remove a good part. After the washout, bananas have elevated levels of Fe, Al, Ti, V, Ba, Pb, most of the rare earth elements, Mo, and Co. In all cases, except Mo, the elevation is much higher in the peel than in the flesh. In the case of Mo, the elevation in banana flesh would translate into a higher nutritional intake of this trace element, which could represent up to 35% of the daily nutritional requirements. Exposure to toxic or potentially toxic elements, does not represent a health risk, since would not exceed 5% of the tolerable daily intake, even in the worst-case scenario.

Development and validation of a multi-residue method for the simultaneous analysis of brominated and organophosphate flame retardants, organochlorine pesticides, and polycyclic aromatic compounds in household dust

Household dust is a sink for multiple toxic chemicals with known or suspected potential health effects. However, most dust exposure studies focus on a few chemicals, which may limit overall understanding of human exposure characteristics because people spend most of their time indoors. This paper describes the development and evaluation of a multi-residue analysis of 20 organochlorine pesticides (OCPs), 15 polycyclic aromatic hydrocarbons (PAHs), 8 polybrominated diphenyl ether congeners (PBDEs), 3 hexabromocyclododecane (HBCDs), 8 synthetic musks (Musks), and 7 organophosphate esters (OPEs) in indoor dusts. After extraction with acetone/hexane (v/v, 1 : 1), all target compounds were fractionated with a Florisil solid-phase extraction (SPE) cartridge into two fractions: PAHs, PBDEs, HBCDs, OCPs and Musks, which were eluted with hexane/dichloromethane, and OPEs eluted with ethyl acetate. Further clean-up using acidified silica 44% cartridges was then performed to enable determination of PBDEs and HBCDs. Instrumental analysis of the target chemicals was performed using gas chromatography (GC) or liquid chromatography (LC) coupled with mass spectrometry (MS) or tandem mass spectrometry (MS/MS). A newly-optimized GC-MS/MS method was employed for the simultaneous determination of PAHs, OCPs, and Musks. The lower limit of quantification (LOQ) values of PAHs, OCPs, and Musks were 0.14-0.92 ng g^-1, 0.06-0.38 ng g^-1 and 0.07-0.40 ng g^-1, respectively. PBDEs were quantified by GC-MS with electron capture negative ionization, and HBCDs and OPEs by LC-MS/MS with electrospray ionization (ESI) in negative and positive ion mode, respectively. Recovery experiments showed that the average recoveries and relative standard deviations were 99-113% and 1-14% for PBDEs, 89-105% and 1-6% for HBCDs, 71-120% and 3-17% for PAHs, 71-112% and 2-17% for OCPs, 77-120% and 2-13% for Musks, and 80-127% and 1-14% for OPEs. Validation experiments showed that the method achieved good accuracy. The developed method was used to analyze SRM 2585 and real indoor dust samples to demonstrate its suitability for routine analysis. The target contaminants were widely detected in SRM 2585 and indoor dust collected from Wuhan of Central China, with PAHs the major species, followed by OPEs, OCPs, and PBDEs.

Pressurized Liquid Extraction (PLE) and QuEChERS evaluation for the analysis of antibiotics in agricultural soils

Vinasse, a liquid waste which originates from the production of ethanol fuel from sugarcane, has been widely used as soil amendment in Brazil. An important concern that arises from vinasse reuse is the dissemination of antibiotics to the environment through crop soils. This work evaluated the performance of Pressurized Liquid Extraction (PLE) and QuEChERS (quick, easy, cheap, effective, rugged and safe) to extract several multiple-class antibiotics, such as cephalosporins, fluoroquinolones, ionophores, lincosamides, macrolides, quinolones, streptogramin, sulfonamides, tetracyclines and others, from agricultural soils. The performance of several parameters was evaluated for both PLE and QuEChERS, such as the extraction temperature (for PLE), solvents composition, pH and the addition of EDTA. Both methods were able to extract most target antibiotics. However, QuEChERS showed higher recoveries for macrolides and nitroimidazoles, while PLE was more suitable for fluoroquinolones and ionophores (i.e. monensin). The use of citrate-phosphate buffer at pH 7.0, in combination with methanol for PLE and with acetonitrile for QuEChERS, provided the highest antibiotic recoveries for both methods. The use of EDTA did not increase antibiotic recovery rates for QuEChERS, while the temperature had almost no influence on the extraction efficiency in PLE.•Citrate-phosphate buffer at pH 7.0 provided higher antibiotic recoveries for QuEChERS and PLE.•The combination buffer-methanol provided higher recoveries for PLE.•QuEChERS and PLE methods were able to extract most of the target antibiotics.

Simultaneous analysis of multiclass antibiotic residues in complex environmental matrices by liquid chromatography with tandem quadrupole mass spectrometry

A simultaneous extraction and cleanup method was optimized and validated for the determination of 40 antibiotics from cephalosporin, fluoroquinolone, lincosamide, macrolide, nitroimidazole, quinolone, sulfonamide and tetracycline groups in sediments by liquid chromatography with tandem quadrupole mass spectrometry (LC-MS/MS). The method involved hydration of freeze-dried sediment sample (2.0 g) with 2.5 ml of 0.1 M Na-EDTA McIlvaine buffer and extraction with 5 ml of MeOH and MeCN (1:3 v/v) followed by dispersive solid phase extraction by using 100 mg mix of C18 and PSA (1:2 w/w) and 50 mg MgSO₄ prior to LC-MS/MS analysis. The method was validated for 10, 20, 50 and 100 µg/kg spiking levels by using blank sediment sample obtained from a drinking water reservoir according to the guidelines of European Commission Decision (2002) 2002/657/EC. The method produced clean extracts with generally low matrix effect during LC-MS/MS analysis. The mean recoveries ranged between 24-162%, 48-151%, 51-159%, and 50-149% for 10, 20, 50 and 100 µg/kg spiking levels, respectively, with acceptable precision. The analytical method was sensitive enough to achieve 0.01-34.3 µg/kg and 0.03-115 µg/kg limits of detection and quantitation, respectively. The scope of the method was demonstrated by analyzing complex solid environmental matrices (chicken manure, swine manure, poultry feed and soil) spiked at 10, 20, 50 and 100 µg/kg levels. The method was also applied for the antibiotic analysis in samples with incurred residues. Different matrices in the order of the magnitude as sediments < poultry feed < swine manure < soil < chicken manure were detected with the residues of fluoroquinolone, macrolide, sulfonamide and tetracycline antibiotics.

Health risk assessment of neonicotinoid insecticide residues in pistachio using a QuEChERS-based method in combination with HPLC-UV

There is an increasing need to address the potential risks arising from combined exposures to multiple residues from pesticides in the diet. Pesticide residue-related pollution is a problem that arises because of the increased use of pesticides in agriculture to meet the growing demands of food production. In this study, pesticide residue data were obtained based on an optimized extraction method. For this purpose, we established a method based on quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction for simultaneous determination of imidacloprid (IMI) and acetamiprid (ACT) in pistachio nuts. The parameters influencing the QuEChERS method were the sample-to-water ratio and adsorbent amounts. As a result, both were optimized to improve the recovery of the analytes as well as the clean-up efficiency of the pistachio matrix. Our results indicated that a freeze-out step and use of primary and secondary amines as an adsorbent led to much cleaner chromatograms with lower baseline drift, without using graphitized carbon black and C₁₈ -based adsorbent, which reduced both cost and time of analysis. Following extraction, the pesticide residues were separated and quantified by reverse-phase HPLC. For validation purposes, recovery studies were carried out using a concentration range from 20 to 2500 μg/L at nine levels. The suitable linearity, precision, and accuracy were obtained with HPLC-UV with recoveries of 70.37%-89.80% for IMI and 81.05%-113.57% for ACT, with relative standard deviations <12%. The validated method was successfully applied to the analysis of pistachio samples collected from a field trial to estimate maximum residue limits. There was no significant health risk for consumers via pistachio consumption.

Simultaneous analysis of multiclass contaminants of emerging concern in sediments by liquid chromatography with tandem quadrupole mass spectrometry

A quick, easy, cheap, effective, rugged, and safe (QuEChERS)-based extraction and simultaneous dispersive solid-phase extraction (dSPE) clean-up method was developed for contaminants of emerging concern (CECs) in sediment samples. Hydration with a phosphate buffer (pH 2.0) and salting out with NaCl and MgSO₄ facilitated the extraction and liquid-liquid portioning of the aqueous and organic phases. Cleanup of the extracts was achieved by florisil and C18 (1:1) sorbents in dSPE with minimal compromise of the analytes. The extracts were clean enough for determination by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The procedure was validated for preservatives, blood lipid regulators, analgesics and anti-inflammatory drugs, plasticizers, and other classes of CECs in sediment matrix spiked at 6 levels between 1- and 40-fold concentrations for CECs of varying analytical sensitivities. The recovery values were generally between approximately 27 and 120% and the relative standard deviation (%RSD) values were below 20% at 10- , 20- , and 40-fold spiking levels, albeit the recoveries for some analytes dropped at low spike concentrations. The method showed high sensitivity where the method detection limits (MDLs) were at low ppb levels for the majority of the analytes that ranged between 0.002 and 1.93 µg/kg. The method performance was also compared with well-established US Environmental Protection Agency (USEPA) Method 1694 by analyzing sediment samples collected from Yundang Lagoon (Xiamen, China) with field-incurred CEC residues. The sediment samples were detected with residues of parabens, gemfibrozil, ketoprofen, naproxen, fenoprofen, diclofenac, miconazole, carbamazepine, benzophenon-3, glibenclamide, sildinafil citrate, and some bisphenol analogues. Environ Toxicol Chem 2019;38:1409-1422. © 2019 SETAC.

Gold Nanoparticles for Qualitative Detection of Deltamethrin and Carbofuran Residues in Soil by Surface Enhanced Raman Scattering (SERS)

The residues of deltamethrin (DM) and carbofuran (CBF) in soil is becoming an intractable problem causing soil hardening and environmental pollution. This paper reports a very simple method via improved reduction of chloroauric acid by the trisodium citrate method for fabricating gold nanoparticles (AuNPs), which were used as a surface enhanced Raman scattering (SERS) active colloids with the advantages of ultrasensitivity, reproducibility and chemical stability. The results demonstrated that the limits of detection (LODs) of the DM and CBF were found to be as low as 0.01 mg/L. The SERS intensity showed a good linear relationship with DM (R² = 0.9908) and CBF (R² = 0.9801) concentration from 0.01 to 10 mg/L. In a practical application, DM and CBF residues in soil were easily detected by SERS with the flexible AuNPs colloids, and the LODs of DM and CBF were found to be as low as 0.056 mg/kg and 0.053 mg/kg, respectively. Moreover, DM in soil could be qualitatively detected by the characteristic peaks at 560 and 1000 cm^-1, and CBF in soil could be qualitatively detected by the characteristic peaks at 1000 and 1299 cm^-1. The determination coefficient (R²_p) for DM and CBF reached 0.9176 and 0.8517 in partial least squares (PLS) model. Overall, it is believed that the prepared AuNPs can provide technical support for the accurate detection of pesticide residues in soil by SERS technique.

Environmental Metabolic Footprinting (EMF) vs. half-life: a new and integrative proxy for the discrimination between control and pesticides exposed sediments in order to further characterise pesticides' environmental impact

Pesticides are regularly used for a variety of applications and are disseminated throughout the environment. These substances may have significant negative impacts. To date, the half-life, t_1/2, was often used to study the fate of pesticides in environmental matrices (water, soil, sediment). However, this value gives limited information. First, it does not evaluate the formation of by-products, resulting in the need for additional experiments to be performed to evaluate biodegradation and biotransformation products. T_1/2 also fails to consider the chemical's impact on biodiversity. Resilience time, a new and integrative proxy, was recently proposed as an alternative to t_1/2, with the potential to evaluate all the post-application effects of the chemical on the environment. The 'Environmental Metabolic Footprinting' (EMF) approach, giving an idea of the resilience time, was used to evaluate the impact of botanicals on soil. The goal is to optimise the EMF to study the impact of a microbial insecticide, the Bacillus thuringiensis israelensis (Bti), on sediment. The difficulty of this work lies in the commercial solution of Bti that is really complex, and this complexity yields chromatograms that are extremely difficult to interpret; t_1/2 cannot be used. No methodologies currently exist to monitor the impact of these compounds on the environment. We will test the EMF to determine if it is sensitive enough to tolerate such complex mixtures. A pure chemical insecticide, the α-cypermethrin, will be also studied. The article shows that the EMF is able to distinguish meta-metabolome differences between control and exposed (with Bti) sediments.

Computational-Based Study of QuEChERS Extraction of Cyclohexanedione Herbicide Residues in Soil by Chemometric Modeling

Assessment of two buffered QuEChERS (quick, easy, cheap, effective, rugged, and safe) versions (i.e., citrate and acetate) modified by including methanol to recover the residues of three cyclohexanedione oxime (CHD) herbicides and three of their byproducts from agricultural soil was performed. In this context, a full second-order face-centered factorial experimental design was developed to quantify the influences of the main five variables (i.e., extraction time, water content, soil weight, and extraction solvent volume and composition) on the target compound recoveries. The fitting equations satisfactorily described the extraction process behavior. The mathematical models also showed the most influencing independent variables (i.e., extraction solvent composition and soil weight). Handling simpler expressions was possible with the acetate QuEChERS but not with the citrate QuEChERS. The recoveries of the CHD residues were close to 100% after performing the extraction under suitable conditions. Furthermore, dispersive solid-phase extraction (dSPE) clean-up steps were assessed to reduce the matrix effect in mass spectrometry. In this sense, the citrate QuEChERS in combination with the PSA + C18 clean-up step was the best option for the extraction of CHD residues.

Validation of QuEChERS analytical technique for organochlorines and synthetic pyrethroids in fruits and vegetables using GC-ECD

In the present day scenario of increasing awareness and concern about the pesticides, it is very important to ensure the quality of data being generated in pesticide residue analysis. To impart confidence in the products, terms like quality assurance and quality control are used as an integral part of quality management. In order to ensure better quality of results in pesticide residue analysis, validation of analytical methods to be used is extremely important. Keeping in view the importance of validation of method, the validation of QuEChERS (quick, easy, cheap, effective, rugged, and safe) a multiresidue method for extraction of 13 organochlorines and seven synthetic pyrethroids in fruits and vegetables followed by GC ECD for quantification was done so as to use this method for analysis of samples received in the laboratory. The method has been validated as per the Guidelines issued by SANCO (French words Sante for Health and Consommateurs for Consumers) in accordance with their document SANCO/XXXX/2013. Various parameters analyzed, viz., linearity, specificity, repeatability, reproducibility, and ruggedness were found to have acceptable values with a per cent RSD of less than 10%. Limit of quantification (LOQ) for the organochlorines was established to be 0.01 and 0.05 mg kg^-1 for the synthetic pyrethroids. The uncertainty of the measurement (MU) for all these compounds ranged between 1 and 10%. The matrix-match calibration was used to compensate the matrix effect on the quantification of the compounds. The overall recovery of the method ranged between 80 and 120%. These results demonstrate the applicability and acceptability of this method in routine estimation of pesticide residues of these 20 pesticides in the fruits and vegetables by the laboratory.

Influence of QuEChERS modifications on recovery and matrix effect during the multi-residue pesticide analysis in soil by GC/MS/MS and GC/ECD/NPD

A QuEChERS extraction followed by GC/MS/MS and GC-μECD/NPD for 216 pesticide and metabolites determination in soil simultaneously were developed and compared. Volume of water, volume and polarity of solvent, and cleanup sorbents (C18, GCB, PSA) were optimized. The QuEChERS with and without purification step were applied to estimate effectiveness of the method. The recovery and matrix effect (ME) were critical parameters within each tested procedure. The optimal method without cleanup was validated. Accuracy (expressed as recovery), precision (expressed as RSD), linearity, LOQ, and uncertainty were determined. The recoveries at the three spiking levels using matrix-matched standards ranged between 65 and 116% with RSD ≤17 and 60-112% with RSD ≤18% for MS/MS and μEC/NP, respectively. The LOQ ranged from 0.005-0.01 mg/kg for MS/MS to 0.05 mg/kg for μEC/NP. The ME for most of pesticides resulted in enhancement of the signal and depended on the analyte and detection system: MS/MS showed ME from -25 to 74%, while μEC/NP from -45 to 96%. A principal component analysis was performed to explain the relationships between physicochemical parameters and ME of 216 pesticides. The QuEChERS protocol without the cleanup step is a promising option to make the method less expensive and faster. This methodology was applied in routine analysis of 263 soil samples in which p,p' DDT was the most frequently detected (23.5% of samples) and pendimethalin with the highest concentration (1.63 mg/kg).

Validation of QuEChERS method for the determination of some pesticide residues in two apple varieties

This study was undertaken to validate the "quick, easy, cheap, effective, rugged and safe" (QuEChERS) method using Golden Delicious and Starking Delicious apple matrices spiked at 0.1 maximum residue limit (MRL), 1.0 MRL and 10 MRL levels of the four pesticides (chlorpyrifos, dimethoate, indoxacarb and imidacloprid). For the extraction and cleanup, original QuEChERS method was followed, then the samples were subjected to liquid chromatography-triple quadrupole mass spectrometry (LC-MS/MS) for chromatographic analyses. According to t test, matrix effect was not significant for chlorpyrifos in both sample matrices, but it was significant for dimethoate, indoxacarb and imidacloprid in both sample matrices. Thus, matrix-matched calibration (MC) was used to compensate matrix effect and quantifications were carried out by using MC. The overall recovery of the method was 90.15% with a relative standard deviation of 13.27% (n = 330). Estimated method detection limit of analytes blew the MRLs. Some other parameters of the method validation, such as recovery, precision, accuracy and linearity were found to be within the required ranges.

New trends in sample preparation techniques for environmental analysis

Environmental samples include a wide variety of complex matrices, with low concentrations of analytes and presence of several interferences. Sample preparation is a critical step and the main source of uncertainties in the analysis of environmental samples, and it is usually laborious, high cost, time consuming, and polluting. In this context, there is increasing interest in developing faster, cost-effective, and environmentally friendly sample preparation techniques. Recently, new methods have been developed and optimized in order to miniaturize extraction steps, to reduce solvent consumption or become solventless, and to automate systems. This review attempts to present an overview of the fundamentals, procedure, and application of the most recently developed sample preparation techniques for the extraction, cleanup, and concentration of organic pollutants from environmental samples. These techniques include: solid phase microextraction, on-line solid phase extraction, microextraction by packed sorbent, dispersive liquid-liquid microextraction, and QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe).

A novel fully automated on-line coupled liquid chromatography-gas chromatography technique used for the determination of organochlorine pesticide residues in tobacco and tobacco products

In this study, a novel fully automated on-line coupled liquid chromatography-gas chromatography (LC-GC) technique was reported and applied for the determination of organochlorine pesticide residues (OCPs) in tobacco and tobacco products. Using a switching valve to isolate the capillary pre-column and the analytical column during the solvent evaporation period, the LC solvent can be completely removed and prevented from reaching the GC column and the detector. The established method was used to determinate the OCPs in tobacco samples. By using Florisil SPE column and employing GPC technique, polarity impurities and large molecule impurities were removed. A dynamic range 1-100ng/mL was achieved with detection limits from 1.5 to 3.3μg/kg. The method exhibited good repeatability and recoveries. This technology may provide an alternative way for trace analysis of complex samples.

Optimization of supercritical fluid extraction method for detection of fluquinconazole and tetraconazole in soil using gas chromatography and confirmation using GC-MS: application to dissipation kinetics

The aim of this study was to establish an analytical method to detect fluquinconazole and tetraconazole in soil using supercritical fluid extraction (SFE) and gas chromatography (GC). The optimal extraction conditions for SFE were: temperature, 60 °C; pressure, 280 kg/cm(2) ; extraction time, 50 min; and a 10% modifier ratio. The linearity of the calibration curves was good and yielded a determination coefficient (R(2) ) ≥ 0.995. The soil samples were fortified with known quantities of the analytes at three different concentrations (0.01, 0.02 and 0.1 µg/g for fluquinconazole; 0.05, 0.1 and 0.5 µg/g for tetraconazole), and the recoveries ranged between 83.7 and 94.1%. The intra- and inter-day relative standard deviations were 1.3-10.6 and 2.2-11.9% for fluquinconazole and tetraconazole, respectively. The limit of detection and limit of quantitation were 0.002 and 0.01 µg/g for fluquinconazole and 0.01 and 0.05 for tetraconazole, respectively. The method was successfully applied to the analysis of soil residues collected from an onion field. The results show that a combination of SFE and GC can be used as an environmentally friendly technique to detect fungicides in soil.

Determination of endosulfan isomers and their metabolites in tap water and commercial samples using microextraction by packed sorbent and GC-MS

A simple, rapid, accurate and sensitive method using microextraction by packed sorbent (MEPS) followed by GC-MS has been pursued for the determination of organochlorine insecticide endosulfan isomers (α and β) and their metabolites (ether, lactone and sulfate). MEPS is a miniaturised version of SPE employing C18 packing material. It is very efficient technique as it employs as low as 10 μL of sample volume. The distinct feature of MEPS is the magnitude of the elution volume that could be directly injected to GC system. Various parameters such as extraction cycles, washing solvent, elution solvent, elution volume and pH, which influenced the MEPS performance, were tested and optimised. The calibration curves were obtained in the concentration range 1-500 ng/mL. The results showed a close correlation coefficient (R(2) > 0.991) for all analytes in the calibration range studied. The LOD and LOQ obtained for GC-MS under selected ion monitoring acquisition are between 0.0038-0.01 and 0.0125-0.033 ng/mL, respectively. The developed method is applicable for the quantification of these compounds in tap water and commercial samples. This method has been shown to be selective as no interferences from endogenous substances were detected by analysis. This method not only decreases sample preparation time but is cheaper, eco-friendly and easier to perform compared to traditional techniques.

DDT residue contamination in sediments from Lake Sibaya in northern KwaZulu-Natal, South Africa: implications for conservation in a World Heritage Site

Maputaland in northern KwaZulu-Natal is a biodiversity hotspot and host to a number of ecologically important systems, including Lake Sibaya, southern Africa's largest natural freshwater lake. The region is malaria endemic and this study reports the presence of DDT and its metabolites in the sediments of Lake Sibaya that have resulted from the widespread and continued use of DDT in the region. DDT residues (p,p'-DDT, p,p'-DDD, and p,p'-DDE) were detected at all 11 sites sampled, with total concentrations ranging from 0.8 to 123 ng g(-1). Total DDT concentrations at Lake Sibaya represent some of the highest levels reported in South Africa, with most samples exceeding sediment quality guideline values. The findings from this study raise concerns and indicate that urgent further work is needed to investigate the potential for bioaccumulation, which could adversely affect breeding fish, bird, and crocodile populations in the region. While this study represents the first report on DDT contamination in Lake Sibaya, results have important implications for a number of other aquatic ecosystems within the Maputaland ecoregion, as well as the many local people who depend on them.

Multi-residue method for the determination of 57 persistent organic pollutants in human milk and colostrum using a QuEChERS-based extraction procedure

Human breast milk represents the best choice for the nutrition of infants. However, in addition to containing beneficial nutrients and antibodies, it can also be considered the best indicator of infant exposure to contaminants. We developed a multi-residue method using a modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) procedure and capillary gas chromatography-triple quadrupole mass spectrometry for the determination of 57 persistent organic pollutants, including 23 organochlorine pesticides, 18 polychlorinated biphenyl (PCB) congeners, and 16 polycyclic aromatic hydrocarbons in human milk and colostrum samples. We have used primary secondary amine in the clean-up step as it gave a more efficient separation of the analytes from fat and superior removal of the co-extracted substances compared with gel permeation chromatography. No significant matrix effect was observed for the tested pollutants, and therefore matrix-matched calibration was not necessary. The average recoveries from spiked samples were in the range of 74.8-113.0 %. The precision was satisfactory, with relative standard deviations below 16 %, while values of 0.1-0.4 μg L(-1) were established as the limit of quantification for all the target analytes (0.05 and 100 μg L(-1)). The method was successfully applied to the analysis of 18 human colostrum and 23 mature milk samples. All the samples tested were positive for at least nine different residues, with some samples containing up to 24 contaminants. Remarkably, the contaminants hexachlorobenzene, p,p'-DDE, PCB 138, PCB 180, phenanthrene, fluoranthene, and pyrene were present in 100 % of the colostrum and mature milk samples analyzed.

Simultaneous analysis of endosulfan, chlorpyrifos, and their metabolites in natural soil and water samples using gas chromatography-tandem mass spectrometry

Analysis of endosulfan, chlorpyrifos, and their nonpolar metabolites in extracts from environmental aqueous and soil samples was performed using a gas chromatography-tandem mass spectrometry (GC-MS/MS) technique. Full-scan GC-MS analysis showed poor sensitivity for some of the metabolites (endodiol and endosulfan ether). A multisegment MS/MS method was developed and MS/MS parameter isolation time, excitation time, excitation voltage, and maximum excitation energy were optimized for chosen precursor ions to enhance selectivity and sensitivity of the analysis. The use of MS/MS with optimized parameters quantified analytes with significantly higher accuracy, and detection limits were lowered to ~1/6th compared with the full-scan method. Co-eluting compounds, chlorpyrifos and chlorpyrifos oxon, were also analyzed successfully in the MS/MS mode by choosing exclusive precursor ions. Analysis of soil and water phase samples from contaminated soil slurry bioreactors showed that the MS/MS method could provide more reliable estimates of these pesticide and metabolites (especially those present in low concentrations) by annulling interferences from soil organic matter.