Analysis Of Pesticides Research Articles

New analytical strategies Amplified with 2D carbon nanomaterials for electrochemical sensing of food pollutants in water and soils sources

Pharmaceutical and food pollutants have threatened global health. Pharmacotherapy has left a positive impression in the field of health and life of people and animals. However, the many unresolved problems brought along with residues of pharmaceuticals in the environmental and food. Consumption of the world's freshwater resources, toxic chemicals, air pollution, plastic waste directly affects water and soil resources. Pesticides have a wide role in pollutants. Therefore, the determination of pesticides is significant to eliminate their negative effects on living things. Nowadays, there are many analytical methods available. However, new analysis methods are still being researched due to certain limitations of traditional methods. Electrochemical sensors have drawn attention because of their superior properties, such as short analysis time, affordability, high sensitivity, and selectivity. The development of new analytical strategies for assessing risks from pharmaceutical to food pollutants in water and soil sources is important for the measurement of different pollutants.Moreover, the 2D-carbon nanomaterials used in the development of electrochemical sensors are widely utilized to enlarge the surface area, increase porosity, and make easy immobilization. Graphene (graphene derivations) and carbon nanotubes integrated nanosensors are widely used for the determination of pesticides. 2D-carbon nanomaterials can be tailored according to the purpose of the study. The characterization and synthesis methods of 2D-carbon nanomaterials are widely explained. Furthermore, enzyme nanobiosensors, especially Acetylcholinesterase (AChE), are widely used to determine pesticides. The three main topics are focused on in this review: 2D-carbon nanomaterials, pesticides that threaten life, and the application of 2D-carbon nanomaterials-based electrochemical sensors. The various developed 2D-carbon nanomaterials-based electrochemical sensors were applied in pharmaceutical forms, fruits, tap/lake water, beverages, and soils sources. This work aims to indicate the recently published paper related to pesticide analysis and highlight the importance of 2D-nanomaterials on sensors.

High Pesticide Exposure Events and Dream-Enacting Behaviors Among US Farmers.

Dream-enacting behavior is a characteristic feature of rapid eye movement sleep behavior disorder, the most specific prodromal marker of synucleinopathies. Pesticide exposure may be associated with dream-enacting behaviors, but epidemiological evidence is limited. To examine high pesticide exposure events in relation to dream-enacting behaviors among farmers in the Agricultural Health Study. We conducted multivariable logistic regression analyses to examine high pesticide exposure events reported from 1993 to 1997 in relation to dream-enacting behaviors assessed from 2013 to 2015 among 11,248 farmers (age 47 ± 11 years). A history of dream-enacting behaviors was reported by 939 (8.3%) farmers. Compared with farmers who did not report any high pesticide exposure event, those who reported were more likely to endorse dream-enacting behaviors 2 decades later (odds ratio=1.75; 95% confidence interval [CI], 1.49-2.05). The association appeared stronger when there was a long delay in washing with soap and water after the event (2.63 [95% CI, 1.62-4.27] for waiting >6 hours vs. 1.71 [95% CI, 1.36-2.15] for washing within 30minutes) and when the exposure involved the respiratory or digestive tract (2.04 [95% CI, 1.62-2.57] vs. 1.58 [95% CI, 1.29-1.93] for dermal contact only). In the analyses of specific pesticides involved, we found positive associations with two organochlorine insecticides (dichlorodiphenyltrichloroethane and lindane), four organophosphate insecticides (phorate, ethoprop, terbufos, and parathion), two herbicides (alachlor and paraquat), and fungicides as a group. This study provides the first epidemiological evidence that high pesticide exposures may be associated with a higher risk of dream-enacting behaviors. © 2022 International Parkinson and Movement Disorder Society.

Fast pesticide analysis using low-pressure gas chromatography paired with a triple quadrupole mass spectrometer equipped with short collision cell technology.

RationaleA proof of concept showing GC–MS/MS analysis time for pesticides can be dramatically reduced while maintaining a similar separation efficiency by combining a low‐pressure gas chromatography (LPGC) column with the enhanced selected reaction monitoring (SRM) switching speed of the short collision cell of a JEOL JMS‐TQ4000GC.MethodsTriple‐quadrupole tandem mass spectrometry (standard EI + at 70 eV) was used to measure pesticides eluting from a low‐pressure gas chromatograph capillary column. Three transitions for each of 244 pesticide compounds were measured within an 11‐min analysis time, and the data were checked to confirm the method's reproducibility and ability to distinguish all three transitions for each pesticide.ResultsAll three transitions for all 244 pesticides were detected in the standard mixture at 1X concentration within the 11‐min analysis time. Relative standard deviation (RSD) of peak areas was less than 15% for 242 pesticides, and I/Q RSDs were less than 10% for 242 compounds. Retention time RSD over 15 replicates was less than 0.1%.ConclusionsResults show that analysis time can be markedly decreased using an LPGC column, and that the ability of the short collision cell to distinguish a large number of coeluting peaks makes the two technologies a natural pairing. The effective measurement of pesticides within a short time could benefit any scientists doing pesticide analysis work.

A novel calibration strategy based on isotopic distribution for high-throughput quantitative analysis of pesticides and veterinary drugs using LC-HRMS

Preparation of calibration curves is a critical step for large-scale quantification. However, this procedure is time-consuming, labor intensive. Herein, a novel isotopologue multipoint calibration (IMC) strategy, was proposed and demonstrated for the simultaneous quantitation of 120 pesticides and 83 veterinary drugs in surface water samples using Liquid Chromatography-High Resolution Mass Spectrometry (LC-HRMS). In this strategy, the natural isotopic distribution was used to generate external calibration curves, eliminating the need of analyst’s adjustment and many sets of chemical standard solutions required in external calibration curves. Additionally, this strategy was comprehensively validated, and the results indicated this strategy had better performance in both accuracy and precision, fully meeting the requirements for the quantitative analysis. Interestingly, for the samples with high concentration beyond the upper limit of quantitation, the IMC strategy could avoid samples dilution by monitoring the less abundant isotopic channels. Furthermore, the IMC method was successfully applied in the surface water samples collected from Anhui province, China. Among which, sulfamethoxazole and imidacoprid were the main contributors. In conclusion, we present a promising LC-HRMS strategy for the accurate quantitation of small molecules, which has a potential application in food and environmental analysis.

Simultaneous multi-residue pesticide analysis in southern Brazilian soil based on chemometric tools and QuEChERS-LC-DAD/FLD method.

A simple and straightforward QuEChERS extraction method was proposed for the simultaneous determination of atrazine (ATZ), desethylatrazine (DEA), desisopropylatrazine (DIA), carbaryl (CBL), carbendazim (CBD), and diuron (DIU) in soil with high agricultural activity from southeastern Brazil, using high-performance liquid chromatography-diode-array detection/fluorescence detection. Screening studies carried out by 24 factorial design indicate better recoveries when less sample (1.0g) and the volume of solvent (2.0mL of ACN) were applied, compared to the original QuEChERS method. Furthermore, interactions between factors were not negligible in the experimental set, except for ATZ and DIU, in which only water volume influenced their recovery. The influence of the type (primary secondary amine (PSA), C18, and Florisil) and the sorbent amount ratio to the compounds' concentration were also considered. PSA (25mg) was selected as the best sorbent without losing analytical response. The limits of quantification (LOQ) were estimated to be 5.0 to 15µgkg-1 in the soil matrix. Analytical performances were consistent with linearity (R2 ≥ 0.998), recovery from 74.7 to 108%, and relative standard deviations (RSD) between 2.6 and 20.2%. Robustness was assessed by fractional factorial Plackett-Burman design. The method is recommended for chemicals that are soluble in water, and it was successfully applied in the analysis of real soil samples containing the analytes in the range of μg kg-1, proving to be suitable for the study of soils strongly impacted by agricultural activity.

Improved magnetic solid-phase extraction based on magnetic sorbent obtained from sand for the extraction of pesticides from fruit juice.

A combination of magnetic solid-phase extraction using an efficient and cheap magnetic sorbent obtained from sand and dispersive liquid-liquid microextraction has been developed for the extraction of nine multiclass pesticides (clodinafop-propargyl, haloxyfop-R-methyl, fenoxaprop-P-ethyl, oxadiazon, penconazole, diniconazole, chlorpyrifos, fenazaquin, and fenpropathrin) from commercial fruit juices (sour cherry, pomegranate, grape, watermelon, orange, apricot, and peach juices). The enriched pesticides were determined by gas chromatography-flame ionization detector and gas chromatography-mass spectrometry. The sorbent was natural iron oxide entrapped in silica along with some impurities. In this method, to extract the analytes from the samples, an appropriate amount of the magnetic sorbent (at mg level) is added. Then the sorbent particles are isolated from the solution using an external magnetic field and the adsorbed analytes are desorbed from the sorbent by acetone. In the following, a dispersive liquid-liquid microextraction procedure is carried out to concentrate the analytes more and to reach low limits of detection. Under optimized extraction conditions, the method revealed satisfactory repeatability (relative standard deviation ≤8% for intra-day and inter-day precision), reasonable extraction recovery (43.3-55.9%), high enrichment factors (433-559), and low limits of detection (0.45-0.89 μg L-1 ). The method was applied in the analysis of pesticides in various fruit juices. Chlorpyrifos was found in peach juice at a concentration of 27 ± 2 μg L-1 (n=3) using a gas chromatography-flame ionization detector. To verify the results, the peach juice was also injected into gas chromatography-mass spectrometry after applying the proposed extraction method. © 2022 Society of Chemical Industry.

Hydrophobic Eutectic Solvent-Based Dispersive Liquid-Liquid Microextraction Applied to the Analysis of Pesticides in Wine.

A green solvent-based DLLME/HPLC-MS method for the determination of 19 pesticides in wine samples has been developed. The extractant solvent is a hydrophobic eutectic mixture composed of L-menthol and butylated hydroxytoluene in a molar ratio of 3:1. The endogenous ethanol of wine has been used as dispersive solvent, in order to avoid the solidification of the extracts under 19 °C. The mobile phase composition, the elution gradient and the sample injection volume were optimized in order to make this hydrophobic mixture compatible with conventional reversed phase chromatography and electrospray ionization. The method was validated in matrix, using a wine free from the target compounds. Average recovery as high as 80%, precision between 3 and 14%, and limits of detection and quantification much lower than the maximum residue levels (MRLs) for grapes and wines fixed by the EU regulation, make this multiresidue method fitted for the purpose, with the further advantages of being quick, cheap and in compliance with the green analytical chemistry. From the analysis of 11 commercial wines it was found that just in a bio sample the target compounds were not detectable or lower than quantification limit; as for the other samples, the most widespread and abundant pesticides were methoxyfenozide and boscalid, but their levels were much lower than the relative MRLs.

Quality control of pesticide using infrared spectroscopic coupled with fingerprint analysis

The public concern and increasing awareness of pesticide calls for methods available to assure quality and authenticity. Spectra matching is widely used in various applications including the search for a spectrum of an unknown compound in an existing spectral database and quality control by means of comparing the spectra of products with standards. Although the infrared spectroscopy (IR) fingerprint has many applications in a lot of areas, there are several limitations in pesticide. The pesticide formulation is a significant impediment against analyzing IR fingerprint of pesticide with similarity estimation.In the present study, a novel strategy combining Fourier-transform infrared spectroscopy (FT-IR) analysis was developed and validated to allow comprehensive analysis and rapid authentication of pesticide. A pesticide IR spectral database which included 604 pesticide standards was established. A simple, fast, and environmentally friendly IR-based pre-treatment method was proposed that can eliminate the negative effect of pesticide formulation on similarity estimation. In order to verify the effectiveness of proposed method, 30 pesticide samples were randomly collected from market, including liquid and solid, with the concentration of active components from 1% to 80%.For 30 samples, the proposed strategy resulted in a 90% accuracy rate and a 3.33% error rate based on the liquid chromatography (LC) data. It is therefore clear that IR spectral database combining with the proposed pre-treatment appear to be a promising tool for monitoring and analysis in the pesticide industry.

Multiclass Comparative Analysis of Veterinary Drugs, Mycotoxins, and Pesticides in Bovine Milk by Ultrahigh-Performance Liquid Chromatography-Hybrid Quadrupole-Linear Ion Trap Mass Spectrometry.

A multiclass and multiresidue method for simultaneously screening and confirming veterinary drugs, mycotoxins, and pesticides in bovine milk was developed and validated with ultrahigh-performance liquid chromatography–hybrid quadrupole–linear ion trap mass spectrometry (UHPLC-Qtrap-MS). A total of 209 targeted contaminants were effectively extracted using an optimized QuEChERS method. Quantitative and qualitative confirmation were achieved simultaneously by multiple reaction monitoring–information-dependent acquisition–enhanced product ion (MRM-IDA-EPI) scan mode. The validation results exhibited a good sensitivity with the LOQs of 0.05–5 μg/kg, which was satisfactory for their MRLs in China or EU. The recoveries of in-house spiked samples were in the range of 51.20–129.76% with relative standard deviations (RSD) between replicates (n = 3) 0.82% and 19.76%. The test results of 140 milk samples from supermarkets and dairy farms in China showed that cloxacillin, aflatoxin M1, acetamiprid, and fipronil sulfone were found with lower concentrations. Combined with the residue results from the literature, penicillin G and cloxacillin (beta-lactams), enrofloxacin and ciprofloxacin (fluoroquinolones), and sulfamerazine (sulfonamides) were more frequently detected in different countries and need to receive more attention regarding their monitoring and control.

Smartphone-coupled three-layered paper-based microfluidic chips demonstrating stereoscopic capillary-driven fluid transport towards colorimetric detection of pesticides.

The existence of pesticide residues in the hydrosphere, biosphere, and anthroposphere can cause acute or chronic diseases and deteriorate the environment. Therefore, efficient detection of pesticide residues is of great significance to prevent food poisoning, control food pollution, and protect human lives by recognizing their distribution and concentration. Herein, a novel smartphone-coupled three-layered paper-based microfluidic chip is proposed as a facile platform to detect the pesticides. The stereoscopic capillary-driven fluid transport is enabled by the three-layered microfluidic chip configuration. The detection mechanism is based on the enzyme inhibition reaction and the chromatic reaction. The detection results are obtained by a smartphone and figured out by colorimetric quantitative analysis. Taking advantages of the above merits, we demonstrate the utilization of this smartphone-coupled three-layered paper-based microfluidic chip for the effective analysis of typical pesticides (profenofo and methomyl). The linear ranges of profenofo and methomyl are 0.27-2.1μmol L-1 and 0.14-1.85μmol L-1, respectively. The corresponding limits of detection in the chips are 55nM and 34nM, respectively. The paper-based chips are also highly cost-effective with a total cost of 0.082 ¥ per piece. It can be anticipated that this technique will open new avenues for the mass fabrication of paper-based microfluidic chips and provide state-of-the-art methods in the field of analytical chemistry.

Development of a sustainable dispersive liquid–liquid microextraction based on novel hydrophobic and hydrophilic natural deep eutectic solvents for the analysis of multiclass pesticides in water

A novel green dispersive liquid–liquid microextraction (DLLME) technique based on two new natural deep eutectic solvents (NaDESs) was developed and applied to the extraction of multiclass pesticides in different environmental waters. A hydrophobic NaDES based on monoterpene thymol and myristyl alcohol was prepared in 2:1 M ratio and used as an extraction phase. Additionally, a ternary hydrophilic NaDES composed of alanine, kojic acid, and water in a 1:2:5 M ratio was prepared and applied as disperser solvent. The NaDESs were characterized by ATR-FTIR spectroscopy, NMR spectroscopy, and octanol–water partition coefficient (Kow). The analyses were performed by GC-µECD. The effect of significant parameters influencing extraction efficiency was investigated through a one-at-a-times strategy. The optimized method was validated by matrix-matched calibration, repeatability, and recovery. The method was linear in the concentration ranges of 0.003–100 μg L−1 for 14 pesticides and 0.013–50 μg L−1 for two pesticides with the determination coefficients > 0.9712. The accuracy was assessed by recovery evaluation at the spike levels of 10 and 20 µg/L, in the range of 63.7–104.5%, with RSD ≤ 9.7%. The method was applied to the analysis of five environmental water samples, and various pesticide residues were detected in river water and groundwater samples in the concentrations range of 0.36–1.10 μg L−1. The greenness of the procedure was assessed using the Analytical Eco-Scale. This paper represents the first application of these novel natural deep eutectic solvents in DLLME and, also the first time, for the analysis of multiclass pesticides in water samples.

A green alternative QuEChERS developed based on green deep eutectic solvents coupled with gas chromatography-mass spectrometry for the analysis of pesticides in tea samples

A novel green modified QuEChERS based on green deep eutectic solvents (DES) followed by GC–MS was developed to analyze pesticides in tea samples. Among different tested DESs for the extraction of analytes, ChCl:PEG (1:4) DES showed the highest efficiency. Three-dimensional magnetic graphene was functionalized by ChCl:urea (1:2) natural DES, characterized and used as sorbent in the in-syringe dispersive micro-SPE to cleanup tea extract. Under optimized conditions, linear range was 0.70–500 μg kg−1. The limits of quantification (0.70–1.90 μg kg−1) were lower than the maximum residue levels established by the European Union for pesticides in tea (0.015–0.1 mg kg−1). The method was applied to detect pesticides in green and black teas, and the recoveries were 70.2–105.2%. This work represents the first application of ChCl:PEG DES and 3DGA-Fe3O4/ChCl:urea in extraction of pesticides and tea sample cleanup, respectively. The greenness of procedure was evaluated by Analytical Eco-Scale and Complementary Green Analytical Procedure Index.

Assessment and chemical analysis of macro elements, heavy metals, proximate compositions and pesticides contamination on rice cultivated from Kura LGA, Kano, Nigeria

Six rice brands BG-213, Notore, Das, Kwandala, Jeep and Jamila brands were collected from various locations in Kura local government area of Kano, Nigeria. Rice brands were analyzed for proximate compositions, macro elements, heavy metals and pesticides using standard analytical techniques. Results of proximate compositions analyses indicate that the average mean value of moisture content, crude protein, crude fat, ash content and crude fiber in rice brands were; 10.27, 9.17 3.82, 1.93 and 0.34 % respectively. The average mean concentrations of macro elements (Calcium (Ca) and Magnesium (Mg)) are; 53.5 mg/kg and 46 mg/kg, while mean levels of Heavy Metals: Zinc (Zn), Copper (Cu), Nickel (Ni), Chromium (Cr), Cadmium (Cd) and lead (Pb) were; 11.87, 4.04, 0.06, 0.00, 0.044 and 0.00 mg/kg respectively. Pearson Correlation Coefficient analysis performed on rice brands using MATLAB student version VI software shows results of macro elements and heavy metals were at a significant level of p≥0.05. The GC/MS analysis of organochlorine pesticides in rice brands revealed that the level of pesticides was below the detection limit (BDL) this indicates that brands of rice obtained from the Kura local government area were safe and free from heavy metals and pesticides contamination could be attributed to restriction or regulation for compliance on the application and economy because most of these pesticides are very costly.

Handheld SERS coupled with QuEChERs for the sensitive analysis of multiple pesticides in basmati rice

Pesticides are a safety issue globally and cause serious concerns for the environment, wildlife and human health. The handheld detection of four pesticide residues widely used in Basmati rice production using surface-enhanced Raman spectroscopy (SERS) is reported. Different SERS substrates were synthesised and their plasmonic and Raman scattering properties evaluated. Using this approach, detection limits for pesticide residues were achieved within the range of 5 ppb-75 ppb, in solvent. Various extraction techniques were assessed to recover pesticide residues from spiked Basmati rice. Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERs) acetate extraction was applied and characteristic spectral data for each pesticide was obtained from the spiked matrix and analysed using handheld-SERS. This approach allowed detection limits within the matrix conditions to be markedly improved, due to the rapid aggregation of nanogold caused by the extraction medium. Thus, detection limits for three out of four pesticides were detectable below the Maximum Residue Limits (MRLs) of 10 ppb in Basmati rice. Furthermore, the multiplexing performance of handheld-SERS was assessed in solvent and matrix conditions. This study highlights the great potential of handheld-SERS for the rapid on-site detection of pesticide residues in rice and other commodities.

Quantitative analysis of organophosphate pesticides and dialkylphosphates in duplicate diet samples to identify potential sources of measured urinary dialkylphosphates in Japanese women

Increased levels of dialkylphosphates (DAP) in maternal urine are associated with a variety of adverse developmental outcomes in children. Although urinary DAP levels are usually considered to be a marker of exposure to organophosphate (OP) pesticides, excretion of DAP may also increase by ingesting preformed DAP. To date, no study has quantitatively assessed the possible contribution of the dietary intake of preformed DAP and OP pesticides to urinary levels of DAP. Therefore, we aimed to estimate the levels of 6 DAPs and 84 OP pesticides in duplicate diet samples and urine samples collected from 73 women living in urban areas of Japan in 2018. DAP and OP pesticides were detected in 94% and 45% of diet samples, while DAP was detected in 100% of urinary samples, respectively. The average daily intake of preformed DAP was significantly higher than that of parent OP pesticides in our participants. Dimethylphosphate and diethylphosphate were predominant in the preformed DAP, and the estimated average daily intake of total amount of DAP was 78.3 nmol. Fruits and vegetables were the major dietary sources of DAP. Dietary intake of DAP was positively associated with urinary DAP levels, suggesting that a considerable amount of urinary DAP was derived from ingesting preformed DAP. Our results show that attributing urinary DAP levels exclusively to OP pesticide exposure would result in a substantial overestimation of the exposure level. Therefore, the urinary levels of DAP may not be suitable for evaluating OP pesticide exposure in the general urban population.

Simultaneous quantitative determination of low-concentration ternary pesticide mixtures in wheat flour based on terahertz spectroscopy and BPNN

Terahertz spectroscopy has been widely applied in the quantitative analysis of pesticides, however, it still encounters challenge pursuing high prediction accuracy in multi-component mixtures analysis with ultra-low concentration. Here, back propagation neural network (BPNN) was applied on the determination of ternary pesticide mixtures in wheat flour. By spectral pre-processing and model parameter optimization, high-quality spectra and complete network frame was achieved. On this basis, a novel wavelength selection method was presented and the most efficient peak width was given. Our method here achieved the optimal results, the correlation coefficient of prediction sets (RP) were 0.9913, 0.9948, 0.9923, and corresponding root mean square error (RMSE) were 0.0211%, 0.0176%, 0.0191%. More importantly, the concentration of pesticides in this study was extremely low compared with similar quantitative analysis based on terahertz spectroscopy, which can promote the application of this technology into actual production.

Analysis of low-volatility pesticides in cabbage by high temperature comprehensive two-dimensional gas chromatography.

High-temperature comprehensive two-dimensional gas chromatography (HTGC × GC) using a longitudinally modulated cryogenic system (LMCS) was developed for the analysis of low-volatility pesticides in cabbage. The method applied DB-17HT and DB-5HT as the first and second dimensional (1D and 2D) columns, respectively. Twelve pesticides, namely 6 organochlorines (4,4'-DDT, β-endosulfan, endosulfan sulfate, endrin, heptachlor, and dicofol), 4 carbamates (metolcarb, isoprocarb, methiocarb, and carbofuran), 1 organophosphate (chlorpyrifos), and 1 pyrethroid (permethrin), were spiked into cabbage samples and prepared using QuEChERS. The applied oven temperature was up to 340 °C, enabling the elution of all the target pesticides and the matrix. The effects of initial oven temperature program, temperature ramp rate, LMCS trap temperature, and modulation period (PM) on the separation results were investigated, leading to the suitable conditions of 80 °C, 15 °C min-1, 10 °C, and 12 s, respectively. The method detection limits, signal-to-noise ratio, and recoveries of the compounds were within the ranges of 0.01-0.09 mg kg-1, 4.26-32.7, and 78-104%, respectively. Good linearity ranges within the concentration range of 0.1-1 ppm with R2 > 0.9134 were also obtained with the intra and interday precisions of the peak areas of 0.4-9.8% and 1.0-10.2%, respectively.

Zeolitic imidazolate framework-8 modified magnetic halloysite nanotube-based solid phase extraction for the analysis of carbamate pesticides by ultra-high performance liquid chromatography tandem mass spectrometry.

Zeolitic imidazolate framework-8 modified magnetic halloysite nanotube (MHNTs@ZIF-8) composites were synthesized and evaluated for the first time as an efficient sorbent for the magnetic solid-phase extraction (mSPE) of carbamate pesticides (CPs) from water samples. MHNTs were prepared by coprecipitation, and MHNTs@ZIF-8 composites were assembled in situ at room temperature. After characterization, MHNTs@ZIF-8 was used to extract pirimicarb, propoxur, carbaryl, isoprocarb and fenobucarb via π-π stacking interaction and hydrophobic interaction between the imidazole skeleton of ZIF-8 and benzene rings or benzene-like rings in CPs, as well as the hydrogen bond formed between O in CPs and H in ZIF-8. The effects of the amount of sorbent, ionic strength, type and volume of desorption solvent and adsorption/desorption time were investigated. Under optimum conditions, good linearity was obtained for the analysis of CPs by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) with R2 ≥ 0.9992. The limits of quantification range from 3 to 40 ng L-1 in water. Relative standard deviations (RSDs) were <7%, n = 5, within a batch and <9% among batches. The spiked recoveries were between 81 and 104%. The proposed method has been successfully applied to the determination of CPs in various water samples.

Analysis of pesticides, veterinary drugs, and environmental contaminants in goat and lamb by the QuEChERSER mega-method.

Analysis of chemical residues in foods is a big challenge for developing countries due to lack of financial and professional resources needed to meet international quality standards for trade. However, the implementation of simple multiclass, multi-residue methods in monitoring programs can provide significant benefits to save cost, time, and labor. The aim of this project was to investigate the "quick, easy, cheap, effective, rugged, safe, efficient, and robust" (QuEChERSER) mega-method for the fatty muscle matrices of goat and lamb. To achieve wide analytical scope covering pesticides, environmental contaminants, and veterinary drugs, extracts were analyzed by both ultrahigh-performance liquid and low-pressure gas chromatography (UHPLC and LPGC) coupled with tandem mass spectrometry (MS/MS). The QuEChERSER mega-method was validated in ovine (goat) and caprine (lamb) muscles at four different spiking levels with 10 replicates per level for a total of 330 analytes and metabolites, consisting of 225 pesticides, 89 veterinary drugs, and 16 polychlorinated biphenyls (PCBs). In the case of LPGC-MS/MS (preceded by automated "instrument-top sample preparation"), 92% and 82% of the analytes met the data quality objectives of 70-120% recovery and <20% RSD for goat and lamb, respectively. For UHPLC-MS/MS, 95% and 92% of the analytes met the acceptable validation criteria in goat and lamb, respectively. Thus, the QuEChERSER mega-method has been demonstrated to be a useful streamlined approach to more efficiently replace multiple methods currently used to cover the same analytical scope.

Synthesis and application of new silver and sulfur decorated S-doped reduced graphene oxide in ultra-trace analysis of pesticides by ion mobility spectrometry.

In this research study, a novel, facile, and affordable method is presented for the synthesis of a Ag/S/S-RGO nanocomposite. The resulting new nanocomposite was identified by FT-IR, XRD, FESEM, XPS, BET and EDX and employed as a rapid and effective adsorbent with acceptable absorption capacity for the analysis of various pesticides by dispersive solid-phase microextraction combined with ion mobility spectrometry. The main experimental parameters of the method were optimized such as the type of desorption solvent, pH of the sample solution, type of buffer, amount of the sorbent (Ag/S/S-RGO), sorption/desorption time, etc. Under the optimized conditions, linear dynamic ranges of 0.5-110.0, 1.0-110.0, and 0.8-90.0 ng mL-1 were achieved, with limits of detection of 0.25, 0.35, and 0.25 ng mL-1 for simazine, alachlor, and haloxyfop, respectively. The relative standard deviations (RSD%) were obtained as <5.0%. Eventually, the method was utilized for the simultaneous determination of simazine, alachlor, and haloxyfop in environmental and agricultural samples with recoveries between 95.0 and 104.6%.