Gas Chromatography-electron Capture Detection Research Articles

Post-synthetic modification of covalent organic framework for efficient adsorption of organochlorine pesticides from cattle's milk

Analysis of organochlorine pesticides (OCPs) residues in milk faces a significant challenge. Herein, a sea urchin structured covalent organic framework bearing boric acid groups named COF-B(OH)2 was synthesized and applied as a coating material for solid-phase microextraction (SPME) of the OCPs in cattle’s milk. Its performance was superior to that of three commonly used commercial SPME fibers, which could be due to the coexistence of hydrogen bonding, halogen bonding, π-stacking and electrostatic interactions. Besides, the fiber coating displayed good stability and reusability. After optimization, a COF-B(OH)2 based SPME coupled with gas chromatography-electron capture detection was established for the sensitive detection of the OCPs from milk samples. The limits of detection (S/N = 3) were between 0.04 and 1.0 μg kg−1. Satisfactory accuracy was achieved with the method recoveries in the range of 87.5 % to 112.5 %. These results manifest the feasibility of the COF-B(OH)2 coated fiber for the enrichment of the trace OCPs from milk samples.

Analyzing Alkyl Bromide Genotoxic Impurities in Febuxostat Based on Static Headspace Sampling and GC-ECD.

Herein, a sensitive and selective gas chromatography-electron capture detector (GC-ECD) method was developed and validated for the quantification of trace levels of five bromo-containing genotoxic impurities in Febuxostat active pharmaceutical ingredient (API) after headspace sampling (HS). Multivariate experimental designs for the optimization of static headspace parameters were conducted in two stages using fractional factorial design (FFD) and central composite design (CCD). The optimum headspace conditions were 5 min of extraction time and a 120 °C extraction temperature. Baseline separation on the analytes against halogenated solvents was carried out using an Agilent DB-624 (30 m × 0.32 mm I.D., 1.8 μm film thickness) stationary phase under isothermal conditions. The method was validated according to ICH guidelines in terms of specificity, linearity, the limits of detection and quantification, precision and accuracy. The linearity was assessed in the range of 5-150% with respect to the specification limit. The achieved LOD and LOQ values ranged between 0.003 and 0.009 and 0.01 and 0.03 μg mL-1, respectively. The accuracy of the method (expressed as relative recovery) was in the range of 81.5-118.2%, while the precision (repeatability, inter-day) was less than 9.9% in all cases. The validated analytical protocol has been successfully applied to the determination of the impurities in various Febuxostat API batch samples.

Exposure of polychlorinated biphenyls via indoor dust particles and their health risks in Dhaka City, Bangladesh

This study is a pioneer evaluation of Polychlorinated Biphenyls (PCBs) within the indoor environment of the megacity Dhaka, Bangladesh. It assessed the occurrence, distribution and associated human health risks of selected 6 PCB congeners in four types of buildings (commercial, industrial, institutional, and residential). Dust samples were collected from the air conditioner filters and subsequently analyzed by Gas Chromatography- Electron Capture Detector (GC-ECD). ∑6 PCB concentrations in commercial, industrial, institutional, and residential buildings ranged from 168 ± 59.42 to 3419 ± 1307, 590 ± 217 to 4669 ± 1731, 244 ± 89.08 to 2538 ± 779, and 161 ± 60.54 to 5413 ± 2136 ng/g, respectively. Considering the total PCB loads from each building type, the industrial category revealed the maximum concentration (19176 ± 1141 ng/g), followed by commercial, residential, and institutional, meaning industrial buildings are more susceptible to PCBs exposure. The heavy PCBs (hexa- and hepta-CBs) were dominant over the light PCBs (di-, tri-, and tetra-CBs). All hazard index (HI) values, except PCB-180, were below 1, suggesting a lower risk of non-carcinogenic effect. The incremental lifetime cancer risk (CR) values were below 10−03, indicating no high carcinogenic risk of the human population from PCB-contaminated dust through the exposure routes.

Differential degradation dynamics of λ-cyhalothrin in mineral and peat soils: a comparative study under laboratory condition

Dissipation kinetics of λ-cyhalothrin in mineral and peat soils of Semongok (mineral soil) and Sibu (peat soil) farms was investigated in a laboratory incubation experiment under different temperature and moisture conditions at normal and double application dosages. The soil was spiked with λ-cyhalothrin at 5 and 25 µg/g soil, respectively. The soil moisture content was adjusted to 20, 40, and 60% of field capacity and then incubated in three climatic chambers at 15, 25, and 35 °C. Samples were collected at 0, 7, 21, 42, 70, and 105 days and analysed by Gas Chromatography-Electron Capture Detector (GC-ECD). Pesticides from the soil were extracted via a facile-modified QuEChERS method. Recovery studies of λ-cyhalothrin in mineral and peat soils were carried out at 0.05, 0.1, 0.5 and 1.0 µg/g fortification levels. The percentage of recovered amount was in the range of 81.4–95.0% and 81.3–86.5% for mineral and peat soils, respectively which falls within the acceptable recovery range of 70.0–120.0%. Factors i.e., soil carbon content, moisture, temperature, and applied dosage that render the degradation of λ-cyhalothrin in mineral and peat soils were evaluated. Findings showed that faster λ-cyhalothrin degradation took place in soil that contained low organic carbon content (< 12%), low soil moisture (≤ 20%) and incubated under higher temperatures (≤ 35 °C). Degradation of λ-cyhalothrin was described by first-order kinetics in both mineral and peat soils at various conditions. Half-lives of λ-cyhalothrin in mineral soil were shorter compared to peat soil. This is due to its lower carbon content and lower soil organic matter availability. This study provides significant information to the agriculture industry and farmers on the important factors such as soil properties, environmental conditions and application dosage that will influence the fate of pesticides in soil.Graphical abstract

Screening, characterization and optimization for synergistic interaction of potential dichlorodiphenyltrichloroethane degrading fungi isolated from agro-industrial effluent and farm soil

Dichlorodiphenyltrichloroethane (DDT) is a recalcitrant synthetic chemical that threatens the environment. Despite being banned in most industrialized nations, DDT is still used as a pesticide to fight malaria and agricultural pests. The main objective of this study is to screen, characterize, and evaluate potential DDT-degrading fungi and their synergetic interaction effects for mycoremediation purpose. The soil and effluent samples were collected from Ziway, Koka, and Addis Ababa. Fungal isolation and screening were performed using a serial dilution on potato dextrose agar growth media. Matrix-Assisted Laser Desorption, Ionization, and Time of Flight Mass Spectrometry technology was used for fungal identification and the selected isolates AS1 and T1 were identified as Aspergillus niger and Trichoderma koningii. Fungal biomass production and sporulation capacity were examined and optimized using a Box-Behnken experimental design. The potential DDT-tolerant fungi were studied based on growth factor optimization. The optimization results revealed that the co-inoculated isolates AS1T1 had a maximum biomass (1.01 ± 0.16g) and spore count (5.74 ± 0.37 log spore/mL) and were selected as possible DDT-degrading fungi. Gas Chromatograph-Electron Capture Detector technology was used for the DDT degradation study. Its analysis confirmed that fungal-co-cultured Aspergillus niger and Trichoderma koningii in DDT-amended liquid medium were able to degrade DDT into its metabolites (DDE and DDD). The results also revealed that 99.5–99.99% of DDT and its metabolites degraded from initial concentrations of 1750, 3500, 5250, and 7000 ppm. The co-inoculated fungi Aspergillus niger and Trichoderma koningii are promising candidates for the removal of DDT and its metabolites from polluted environments.

Magnetic Persimmon Leaf Composite: Preparation and Application in Magnetic Solid-Phase Extraction of Pesticides in Water Samples.

In recent years, the utilization of biomass materials for the removal and detection of water pollutants has garnered considerable attention. This study introduces, for the first time, the preparation of Fe3O4/persimmon leaf magnetic biomass composites. The magnetic composites were employed in a magnetic solid-phase extraction method, coupled with gas chromatography-electron capture detection (GC-ECD), for the analysis of four pesticides (trifluralin, triadimefon, permethrin, and fenvalerate) in environmental water samples. The innovative magnetic persimmon leaf composites were synthesized by in situ generation of Fe3O4 nanoparticles through coprecipitation and loaded onto persimmon leaves. These composites exhibit superparamagnetism with a saturation magnetization of 12.8 emu g-1, facilitating rapid phase separation using a magnetic field and reducing the extraction time to 10 min. Desorption can be achieved within 30 s by aspirating 20 times, eliminating the need for time-consuming and labor-intensive experimental steps like filtration and centrifugation. The specific surface area of the magnetic composite adsorbent increased from 1.3279 m2 g-1 for the original persimmon leaf to 5.4688 m2 g-1. The abundant hydroxyl and carboxyl groups on the composites provide ample adsorption sites, resulting in adsorption capacities ranging from 55.056 mg g-1 to 73.095 mg g-1 for the studied pesticides. The composites exhibited extraction recoveries ranging from 80% to 90% for the studied pesticides. Compared to certain previously reported MSPE methods, this approach achieves equivalent or higher extraction recoveries in a shorter operation time, demonstrating enhanced efficiency and convenience. Good linearity of the target analytes was obtained within the range of 0.75-1500 μg L-1, with a determination of coefficient (R2) greater than 0.999. These findings contribute to the use of magnetic persimmon leaf biomass materials as effective and environmentally friendly adsorbents for pollutant determination in water samples.

SAT436 Endocrine Disruptor Of Organochlorine Pesticides Levels In Saudi Arabian Produce

Abstract Disclosure: M.S. Alokail: None. N.M. Al-Daghri: None. A.M. Alnaami: None. S. Sabico: None. S.D. Hussain: None. O.E. Amer: None. S.H. Abd-Alrahman: None. Food monitoring (FM) is a system used to evaluate and monitor hazardous contaminants, including pollutants such as organochlorine pesticides (OCPs). Long term exposure to organochlorine pesticides (OCPs) can lead to a variety of endocrine and reproductive disruptors including gonadal changes, changes in reproductive behavior, reduced sperm quality, an increase in organ malformations, testicular failure, fetal defects, thyroid dysfunction, and lactation. The present study aimed to determine and quantify OCPs in different local produce collected from different regions in Saudi Arabia. A total of 179 local produce samples were obtained in four regions in Saudi Arabia: Riyadh (N=55), Qassim (N=61), Eastern province (N=38) and Western region (N=25). Solid phase extraction method (QuEChERS) was used to detect OCP residues in samples and levels were quantified using gas chromatograph-electron capture detector (GC-ECD). The results have shown that a total of 11 OCPs were detected overall (9 OCPs in Qassim, Eastern province and Riyadh; 8 in Western region). Levels of alpha BHC was highest in Riyadh; 6 OCPs were highest in Qassim (Beta-BHC, Delta BCH, Dieldrin, Gamma-BHC, heptachlorepoxide and heptachlor); 4 OCPs were highest in the Eastern province (DDD, DDE, endosulfan and endrin), with endrin and endosulfan having the highest levels among all OCPs assessed. A total of 6 OCPs were found in all regions at varying concentrations (Beta-BHC, DDE, Delta-BCH, Dieldrin, endosulfan and heptachlor. Worthy to note is that heptachlorepoxide was found only in Qassim. In conclusion, the endocrine disruptor pesticides such as OCP residues require further investigation for a possible etiologic role in some hormone related cancers such as breast cancer. Presentation: Saturday, June 17, 2023

Trihalomethanes and physicochemical quality of drinking water in Addis Ababa, Ethiopia

BackgroundTrihalomethanes (THMs) are the most dominant fraction of all the byproducts formed during chlorination of water. Disinfection by product (DBP) formation in water is a function of numerous factors, including pH, temperature, residual chlorine, source water characteristics, and organic matter. No study has determined the THM level in the drinking water supply of Addis Ababa, Ethiopia. MethodsA cross-sectional design was conducted to collect water samples in the water supply distribution networks of Addis Ababa, Ethiopia. Twenty-one (21) sampling stations yielded a total of one hundred twenty (120) samples of drinking water. The sample handling and collection procedures were carried out in accordance with USEPA guidelines. A DB-5 capillary column was used to separate the THMs, which were detected using GC-ECD (gas chromatography-electron capture detector). Spectrophotometric and in situ methods were used for physicochemical parameters. Redundancy analysis (RDA) was used for data analysis of trihalomethanes and environmental variables using CANOCO 4.5. ResultsThe mean concentration of total trihalomethanes in drinking water in Addis Ababa was 76.3 μg/L. The concentration of chloroform in the drinking water supply in Addis Ababa, Ethiopia, ranged between 4.03 and 79.4 μg/L. The mean total THMs in the Legedadi and Gefersa water supply systems were 77.4 μg/L and 69.66 μg/L, respectively. The residual chlorine, phosphates, UV absorbance at 254 nm, and combined chlorine had positive correlations with THM formation. However, electron conductivity had a negative correlation with THM formation. ConclusionsChloroform contributed the most to TTHMs in nearly all samples. The residual chlorine, UV absorbance, phosphate and hardness as calcium, and electron conductivity were found to be the main predictors determining the abundance and distribution of trihalomethanes. The monitoring and regulation of the THMs is required on a regular basis to analyse trends and guide the water treatment and distribution system.

Dissipation kinetics, residue determination and consumer risk assessment of acephate on green pea by gas chromatography-electron capture detector.

The present study on "acephate persistence on green pea" was conducted in SKUAST-Kashmir. The study aimed to determine the persistence, dissipation kinetics and waiting period of acephate on green pea. Acephate was sprayed at 75%soluble powder (SP) at 560 g a.i.ha-1 at the fruiting stage followed by another application at a 10 day interval. A rapid and accurate method (quick, easy, cheap, effective, rugged and safe, QuEChERS) was used for extraction and the residue was determined by gas chromatography-electron capture detection on a CPSIL-8CB capillary column (0.25um film thickness, 0.25 mm i.d, 30 m length). At the fortification levels of 0.05, 0.1 and 0.5mg kg-1 , the percentage recovery of acephate on green pea was found in the range of 71-107%. The initial deposit of green pea was estimated to be 0.37 mg kg-1 . At the indicated dose, the residue of acephate on green pea dissipated below the limit of quantification of 0.05 mg kg-1 after 10days. Acephate degradation was quick in green pea, with a half-life of 4.07 days. For safe eating of green peas, a 10 day waiting period is recommended. The gas chromatography-electron capture detection technique was validated by following the SANTE standards.

The effect of different decontamination processes on the residues of fipronil and its metabolites in chili fruits (Capsicum annuum L.).

Fipronil is a broad-spectrum phenyl pyrazole insecticide that has a high degree of environmental toxicity. Commonly available chilies in the market are treated with fipronil insecticides. Demand for insecticide-free chili has thus been increasing globally. This needs various sustainable and economical methods to remove insecticides from chilies. The present study examined the effectiveness of several cleaning methods to remove pesticide residues in chili fruits. A supervised field trial was conducted in randomized block design at Rajasthan Agricultural Research Institute, Durgapura, Jaipur, India. Chili samples were subjected to seven different household methods. The samples were extracted using the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method. The residues were analyzed using a gas chromatograph-electron capture detector and confirmed by GC-MS. Of the seven methods, the acetic acid treatment removes the maximum residue effect of fipronil and its metabolites (desulfinyl [MB046513]), sulfide (MB045950), and sulfone (MB046136) on chili fruits. By contrast, the tap water treatment was the least effective. The Food Safety and Standards Authority of India (FSSAI) have set the maximum residue limit value of 0.001 mg kg-1 for fipronil on green chili.

Method Validation for Pesticide Residues on Rice Grain in Aceh Besar District, Indonesia Using Gas Chromatography-Electron Capture Detector (GC-ECD)

Analysis of pesticide residues in rice in Aceh Besar District using the Gas Chromatography – Electron Capture Detector (GC-ECD) method has been carried out. This study aims to validate the analytical method and determine the pesticide residue levels of Dichlorvos, Dimethoate, Bifenthrin, and λ-Cyhalothrin in rice samples. Rice samples in branded rice were taken from the Districts of Want Jaya, Indrapuri, Darussalam, Suka Makmur, Simpang Tiga, Kuta Baro, and ground using a grinder. The powder sample was extracted by the QuEChERS method and analyzed by GC-ECD. The results of the linearity test have met the requirements with the coefficient of determination (R2), which is an average of 0.98. The LOD values ranged from 0.013 to 0.017 mg/kg, while the LOQ ranged from 0.022 to 0.079 mg/kg. The results of precision and reproducibility (% RSD, n = 6) show the values of 0.56 - 1.26% and 1.14 - 2.19%, respectively, and the accuracy value (%Recovery) shows the results of 99.71 - 101.84%, with an RSD value of 2.42 - 3.59%, meet the requirement of 20%. The results of the analysis of the sample showed that sample A had a large %Recovery value in the Dichlorvos analyte, namely 139.10%, with the calculation that the Dichlorvos analyte contained 0.0206 mg/Kg. This value has not passed the MLR set by the European Food Safety Authority, which is 0.2 mg/Kg. In the other rice samples, no pesticide residue analytes were detected. The calculation of %Recovery of each analyte in the spiked sample ranged from 80-101%, which indicated that the pesticide residue analysis carried out had good accuracy, namely the requirement of 70-120%.

Detailed Characterization of Chlorides and Oxides in Plastic Waste Pyrolysis Oil from Paper Mills by GC-ECD and GC-MS with Solid Phase Extraction

Identification of heteroatom compounds containing chlorine and oxygen in plastic waste pyrolysis oil (PWPO) is significant for processing. A quantitative method for 32 chlorinated hydrocarbons in PWPO was established by a gas chromatography-electron capture detector. Eight chlorinated hydrocarbons were found in PWPO, accounting for 14.0% of the total chlorine, with 1,2-dichloroethane having the highest amount. 73 compounds in the polar fraction of PWPO were identified using solid phase extraction and gas chromatography-mass spectrometry. The proportions of these compounds in the polar fraction decreased in the order of esters, nitriles, ketones, acids (including anhydride), chloroesters, phenols, alcohols, ethers, aldehydes, trienes, and siloxanes. The polar fraction contained nine chlorides. All of these chlorides were in the form of 2-chloroethyl ester, and 1,4-benzenedicarboxylic acid, di-2-chloroethyl ester, had the highest proportion among the nine chlorides. Finally, the formation pathways of 2-chloroethyl esters were illustrated. These results would provide support for the development of a clean processing technology for PWPO.

DETERMINATION OF POLYCHLORINATED BIPHENYLS (PCBs) IN SURFACE WATER IN ONDO STATE NIGERIA

Polychlorinated biphenyl compounds (PCBs) were included to the Stockholm Convention's list of typical persistent organic pollutants on May 22, 2001. (POPs). Humans have produced PCBs, which are pervasive in the environment. They are a concern for people all around the world because of their toxic, bioaccumulative, long-lasting, hydrophobic, and transboundary characteristics. The study's goals included describing how PCBs are distributed in surface water and evaluating how certain physiochemical factors affect PCB concentrations. Five separate Okitipupa locations—OAUSTECH, Igodan, Okunmo, Idepe, and Lebi/Ofe River—had their water samples taken. The overall average concentration of PCBs discovered in the samples taken from five (5) distinct places was determined to be as follows: OAUSTECH (5.720.13), Igodan (5.520.00), Okunmo (3.480.03), Idepe (21.830.02), and Lebi/Ofe (0.160.00), with their combined probability being determined to be 0.001. Twenty-five (25) PCB congeners were examined using a gas chromatography-electron capture detector (GC-ECD). The majority of congeners were below the detection threshold at every site. Total PCB values varied from 0.16 g/L to 21.83 g/L. The correlation between the overall level of polychlorinated biphenyls and the total organic carbon was positive (0.214), but it was weak (PCBs) and pH, positive (0.096) but poor correlation between the electrical conductivity, and a positive (0.220). The levels found in this investigation, with the exception of one area, were obviously lower than the 0.5μg/l level advised by the WHO. The water's concentration of polychlorinated biphenyls (PCBs) is not significantly impacted by the physicochemical characteristics, and the water is safe to use for household purposes.

Pesticide Exposure among Latinx Children in Rural Farmworker and Urban Non-Farmworker Communities: Associations with Locality and Season.

This study uses repeated measures to document the pesticide exposure of rural and urban Latinx children (age eight at baseline), and to compare these children in terms of the frequency and concentration of their exposure to a large set of pesticides, accounting for season. We used silicone wristbands worn for one week up to ten times at quarterly intervals from 2018 to 2022 to assess pesticide exposure in children from rural farmworker (n = 75) and urban non-farmworker (n = 61) families. We determined the detection and concentrations (ng/g) of 72 pesticides and pesticide degradation products in the wristbands using gas chromatography electron capture detection and gas chromatography mass spectrometry. The most frequently detected pesticide classes were organochlorines, pyrethroids, and organophosphates. Controlling for season, organochlorine or phenylpyrazole detections were less likely for rural children than for urban children. Detections of organochlorines, pyrethroids, or organophosphates were lower in spring and summer versus winter. Controlling for season, urban children had greater concentrations of organochlorines, while rural children had greater concentrations of pyrethroids and Chlorpyrifos. Pesticide concentrations were lower in winter and spring compared with summer and fall. These results further document that pesticides are ubiquitous in the living environment for children in vulnerable, immigrant communities.

Assessment of organochlorine contamination source and ecological risk in the Litani River: polychlorinated biphenyls and organochlorinated pesticides in surface sediments.

In this paper, we investigate for the first time the contamination source and the ecological risk associated to organochlorinated compounds in the Litani system. For this purpose, the levels of 7 polychlorinated biphenyls (PCBs) and 13 organochlorinated pesticides (OCPs) were assessed, using a microwave-assisted extraction coupled to gas chromatography-electron capture detector (MAE/GC-ECD) method, in surficial sediments from 30 sites along the main course of the river, two major tributaries, and the Quaraoun Lake. ∑7PCBs exhibited total concentrations ranging from 0.11 to 8 ng g-1 of dry weight and are not able apparently to pose ecological risks since none of the samples showed concentration above the effects range low (ERL) guideline (22.7 ng g-1). The detected levels of OCPs in the river were significantly higher than those of PCBs; ∑13OCPs range from 0.5 to 46.5 ng g-1 of dry weight. Overall, the integrated eco-toxicological risk imposed by the organochlorine contamination in the Litani River, estimated as the mean effects range medium quotient (mERMq), is considered low with risk probability lower than 21% in all sites. The six dichlorodiphenyltrichloroethane-based pesticides (∑6DDT) contributed to more than 70% of the mERMq in 15 over the 29 included sites. Moreover, the approach of ∑6DDT/∑7PCB ratios was applied to investigate the contamination source. ∑6DDT/∑7PCB was higher than one in all samples suggesting that the organochlorine contamination result from agricultural activities set in the surrounding areas of the Litani River.

Molecularly imprinted conjugated microporous polymer composite as solid phase extraction adsorbent for the extraction of phenolic endocrine disrupting chemicals in beverages

A molecularly imprinted triazine-based conjugated microporous polymer composite with rich porosity and good selectivity was prepared and used as the adsorbent of solid-phase extraction (SPE). The composite-based SPE for the three phenolic endocrine disrupting chemicals (nonylphenol, octylphenol and bisphenol A) in different beverages followed by derivatization with heptafluorobutyric anhydride and then detection by gas chromatography-electron capture detector was developed. The variables mainly affecting the extraction and derivatization were evaluated. Under the optimal conditions, the limits of detection (S/N = 3) of the established method for the analytes ranged from 0.12 to 1.20 µg L−1. The linear response range of the method was 0.40–50.0 µg L−1, with the coefficients of determination falling in the range of 0.9906–0.9994. The relative recoveries of the phenolic endocrine disrupting chemicals in spiked beverage samples at three concentration levels (high, middle, and low) were in the range of 80.6% −117% with the relative standard deviations of 3.5%-11%. The established method exhibits a potential in the monitoring of trace phenolic endocrine disrupting chemicals in real beverage samples.

IMPACT OF DECONTAMINATION PROCESSES ON THE REDUCTION OF PESTICIDE RESIDUES IN GREEN CHILLI

This study has been designed to determine the extent of pesticide residue removal from chilli fruits through common household practices. One time foliar application of quinalphos, profenophos, ethion, cyhalothrin, imidacloprid, and acetamiprid was done as a tank mix at recommended doses at 50% fruit formation stage. Samples were collected after 48 hr of spray, subjected to various decontamination treatments, and analysed using the validated QuEChERS method employing GC-ECD (Gas Chromatograph Electron capture detector), and Liquid Chromatograph Tandem Mass Spectrometer (LC-MS/MS). Compared to all the treatments, soaking in 5% acetic acid for one min was found to be most effective in the removal of quinalphos (23.68%), profenophos (19.47%), ethion (23.33%), and cyhalothrin (25.00%). The next best treatment was found to be soaking for one min in lukewarm water, which removed 20-30% of quinalphos, ethion, cyhalothrin, and acetamiprid residues.

Detection of organochlorine pesticides in estuarine sediments of protected wetlands in Taiwan using high‐resolution gas chromatography/high‐resolution mass spectrometry and gas chromatography‐electron capture detector

AbstractTrace residues of organochlorine pesticides (OCPs) in estuarine surface sediments were investigated at three protected wetlands in southern Taiwan using high‐resolution gas chromatography/high‐resolution mass spectrometry (HRGC/HRMS) and gas chromatography‐electron capture detector (GC‐ECD). This study facilitates the development of new strategies for investigating OCPs, particularly at background levels. Linear relationships were obtained between total OCP concentrations (∑OCP), as analyzed by HRGC/HRMS, and the sediment's total organic carbon (TOC) and water content. It contrasted with the results acquired by GC‐ECD, where no significant relationship was found. GC‐ECD is a rugged option for daily routine practice, particularly in cases of patterns yielded by GC‐ECD is clear; the HRGC/HRMS method provides more reliable qualitative and quantitative capabilities and is highly recommended for studying the fate of OCPs and carrying out risk assessments. The average ∑OCP of these three wetlands by HRGC/HRMS was found in a range of 0.214 to 1.049 ng/g dry weight. The highest OCP level might be attributed to associated irrigation systems receiving massive discharges of domestic sewage from an urban area upstream of the wetland. The ratio of dichlorodiphenyltrichloroethane (DDT) to its metabolites indicated that the DDT residue in these areas was from aged input. According to sediment quality guidelines, adverse ecotoxicological effects of OCPs upon sediments were not expected in these protected wetlands.

Dissipation kinetics, risk assessment, and waiting period of spiromesifen on chili fruits using gas chromatography-electron capture detector.

A supervised field trial was designed in Rajasthan Agricultural Research Institute, Durgapura, Jaipur, Rajasthan, to assess the dissipation and persistence of spiromesifen in chili fruits. Spiromesifen (22.9% suspension concentrate) was sprayed two times at an interval of 10 days at the recommended dose (96 g. a.i. ha-1 ) and double the recommended dose (192 g. a.i. ha-1 ) with four replications. Sampling was done according to the planned interval of days after the second spray. Extraction and cleanup were performed using the modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) method and the spiromesifen residue was analyzed by GC-electron capture detector and confirmation performed using GC-MS. The average initial deposit of spiromesifen was 1.207 mg kg-1 and 1.948 mg kg-1 at the recommended and double the recommended dose, respectively. The half-life values of spiromesifen ranged between 2.7 and 3.2 days at the recommended and double the recommended dose. The safe waiting period was calculated for the respective doses and it was concluded that an average of 7 days is safe for picking. The FSSAI (Food Safety and Standards Authority of India) have set the maximum residue limit of 0.1 mg kg-1 for spiromesifen in green chili. The theoretical maximum residue contribution value of spiromesifen was lower than the maximum permissible intake at both the applications on the 0th day. Hence, there will be no adverse effects on human health after consumption of green chilies.

Persistence and dissipation kinetics of novaluron 9.45% + lambda-cyhalothrin 1.9% ZC insecticides in tomato crop under semi-arid region.

In recent decades, fate studies of pesticides have been a topic of interest worldwide due to human health concerns tomato, contain abundant nutritional phytochemicals and lycopene which is known for antioxidant. Tomato is susceptible to many pest, so to overcome from these pests many insecticides are used, leaving residual effects on the crop. So to find out the persistence, the present study was carried out to investigate the residual levels and dissipation behaviour of novaluron 9.45% + lambda-cyhalothrin 1.9% ZC in tomato crop during Rabi session of 2017-18 in randomized block design. The first spray of insecticide was done at fruit formation stage and second spray at 10-day interval at recommended dose @43.31ga.i.ha-1 and double of recommended dose @86.62ga.i.ha-1. The residue of novaluron determined by HPLC (high-performance liquid chromatography) on 0day (two hours after spraying) was 0.154ppm at lower dose and 0.234ppm at higher dose. The residue of lambda-cyhalothrin determined by GC ECD (gas chromatography electron capture detector) at 0day (two hours after spraying) was 0.451ppm at lower dose and 0.849ppm at higher dose. The deposition of novaluron 9.45% +  lambda-cyhalothrin 1.9% ZC was gradually decreased with increasing days after spraying (DAS). The mean initial deposition of the pesticide novaluron and lambda-cyhalothrin was recorded as 0.154mg/kg, 0.451mg/kg, respectively, at the recommended dose @43.31ga.i.ha-1 while at double of recommended dose @86.62ga.i.ha-1 novaluron and lambda-cyhalothrin, the mean initial deposition of 0.234mg/kg and 0.849mg/kg was recorded, respectively. The residue of the novaluron and lambda-cyhalothrin was at BDL (below determination level) (0.01 and 0.05ppm) on 5th and 7th day, respectively, at lower dose (x), whereas at higher dose (2x) it was below determination level on 7th and 10th day, respectively. In soil samples, the residue levels were at below the determination level (0.01mg/kg) for novaluron and (0.05mg/kg) for lambda-cyhalothrin at both doses. The half-life DT50 of novaluron and lambda-cyhalothrin in the tomato fruit was found to be 2days at recommended dose (X) @43.31ga.i.ha-1 for both the pesticide and at double of the recommended dose @86.62g a.i. ha-1 it was 3 and 2days, respectively.