Electron Capture Detector Research Articles

CCQM-K68.2019, nitrous oxide (N2O) in air, ambient level, final report

Main textThe key comparison CCQM-K68.2019 was aimed at evaluating the level of comparability of laboratories' capabilities for preparing nitrous oxide in air primary reference mixtures at ambient amount fractions, in the range 320 nmol mol−1 to 350 nmol mol−1.The comparison was coordinated by the BIPM and the KRISS. It consisted in the simultaneous comparison of a suite of 2n primary gas standards, two standards to be prepared by each of the n participating laboratories. Two independent analytical methods were used by the BIPM to analyse the amount fraction of N2O in air, namely Gas Chromatography with an Electron Capture Detector (GC−ECD) and Quantum Cascade Laser Absorption Spectroscopy (QCLAS).Since the circulation of the Draft A report in April 2021, four meetings took place with participants to discuss the mathematical treatment of the comparisons results, and several models were proposed. The model chosen by participants is the Bayesian Errors−In−Variables regression with shades of dark uncertainty. In this final report, the Key Comparison Reference Values were obtained with this model, with calculations performed by B Toman and A Possolo.The key comparison CCQM-K68.2019 is considered to present an analytical challenge and therefore classified as Track C comparison in the CCQM nomenclature.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Honey as a bioindicator of environmental organochlorine insecticides contamination.

Honey is a suitable matrix for the evaluation of environmental contaminants including organochlorine insecticides. The present study was conducted to evaluate residues of fifteen organochlorine insecticides in honey samples of unifloral and multifloral origins from Dir, Pakistan. Honey samples (5 g each) were extracted with GC grade organic solvents and then subjected to Rotary Evaporator till dryness. The extracts were then mixed with n-Hexane (5 ml) and purified through Column Chromatography. Purified extracts (1μl each) were processed through Gas Chromatograph coupled with Electron Capture Detector (GC-ECD) for identification and quantification of the insecticides. Of the 15 insecticides tested, 46.7% were detected while 53.3% were not detected in the honey samples. Heptachlor was the most prevalent insecticide with a mean level of 0.0018 mg/kg detected in 80% of the samples followed by β-HCH with a mean level of 0.0016 mg/kg detected in 71.4% of the honey samples. Honey samples from Acacia modesta Wall. were 100% positive for Heptachlor with a mean level of 0.0048 mg/kg followed by β-HCH with a mean level of 0.003 mg/kg and frequency of 83.3%. Minimum levels of the tested insecticides were detected in the unifloral honey from Ziziphus jujuba Mill. Methoxychlor, Endosulfan, Endrin and metabolites of DDT were not detected in the studied honey samples. Some of the tested insecticides are banned in Pakistan but are still detected in honey samples indicating their use in the study area. The detected levels of all insecticides were below the Maximum Residue Levels (MRLs) and safe for consumers. However, the levels detected can cause mortality in insect fauna. The use of banned insecticides is one of the main factors responsible for the declining populations of important insect pollinators including honeybees.

CCQM-P206, nitrous oxide (N2O) in air, ambient level, pilot study run in parallel with CCQM-K68.2019

Main textThe Pilot Study CCQM-P206 was conducted in parallel with the Key Comparison CCQM-K68.2019, which was aimed at evaluating the level of comparability of laboratories' capabilities for nitrous oxide in air primary reference mixtures at ambient amount fractions, in the range 320 nmol mol−1 to 350 nmol mol−1. The Pilot Study was set up to allow the participation of the Scripps Institution of Oceanography of the University of California San Diego (SIO/UCSD) as guest expert laboratory of the CCQM.The SIO/UCSD was invited by the CCQM in view of its long experience in accurate measurements of nitrous oxide in the atmosphere and is the calibration laboratory for this compound in the AGAGE (Advanced Global Atmospheric Gases Experiment) global measurement network. The laboratory has developed a unique method which provides an independent assessment of the N2O amount fraction compared to participants in CCQM-K68.2019. Its participation was also seen as the occasion to contribute to a more general reflexion on the compared advantages of two different systems to ensure traceability: a unique scale maintained by one central laboratory, or the dissemination of materials all traceable to the SI by multiple national metrology institutes.The comparison CCQM-K68.2019 was coordinated by the BIPM and the KRISS. It consisted in the simultaneous comparison of a suite of 2n primary gas standards, two standards to be prepared by each of the n participating laboratories. Two independent analytical methods were used by the BIPM to analyse the amount fraction of N2O in air, namely Gas Chromatography with an Electron Capture Detector (GC−ECD) and Quantum Cascade Laser Absorption Spectroscopy (QCLAS).For the Pilot Study, SIO/UCSD provided results of measurements of the N2O amount fraction in the two standards submitted by the Global Monitoring Laboratory of the National Oceanic and Atmospheric Administration (NOAA), a participant in the Key Comparison. Therefore, this study consists in looking at the agreement between SIO/UCSD measurement results and the Key Comparison reference value.All details on the Key Comparison CCQM-K68.2019, including its protocol and its results, can be found in its report. This report focuses on SIO/UCSD results and agreement with participants in the Key Comparison.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Quantitative detection of organic mercury in whole blood using derivatization and gas chromatographynegative chemical ionization-mass spectrometry

The Minamata disease, first identified in Japan in the 1950s, is caused by severe methylmercury (MeHg) poisoning. To prevent the development of this disease, routine evaluation of MeHg levels in blood samples is crucial. The purpose of this research was to explore the use of derivatization and capillary gas chromatography-negative chemical ionization-mass spectrometry (GC-NCI-MS) for the quantitative detection of both organic and inorganic mercury in blood samples. Alkyl mercury in standard solutions was extracted as halide salts in toluene with hydrohalic acid. Fat contents in whole blood samples were removed by methyl isobutyl ketone and hexane using a cysteine/alkaline solution and then organic mercury was extracted as a bromide complex using toluene and cupper chloride solution. The linearity of the response ratio vs. concentration curves (R2) was 0.987 for methylmercury bromide and 0.990 for ethylmercury bromide. over the calibration range of 0.02 ng/mL to 20 ng/mL. The recovery of MeHg and ethylmercury (EtHg) was 67.1% and 49.3%, respectively. The concentrations of MeHg in whole blood samples determined using GC with an electron capture detector agreed with those determined using GC-NCI-MS, with a correlation coefficient of 0.923. The mean concentration of MeHg in a certified reference material (NMIJ CRM 7402-a) determined using GC-NCI-MS was 0.64 μg/g, comparable with the certified value of 0.58 μg/g. Our study demonstrates a simple and low-cost approach for analyzing mercury in biological samples, although further optimization is required given the relatively low recovery and the concern about the toxicity of methyl isobutyl ketone.

Concentration and Human Health Risk Assessment of Dichlorodiphenyltrichloroethane in Two Species of Fish Muscle from River Gongola Basin and its Dam, Dadinkowa, Gombe State, Nigeria

The concentration of DDT and its metabolites in the two fish species (Clarias gariepinus and Bagrus docmak) from River Gongola basin and its dam, Dadinkowa in Gombe State Nigeria was determined and human health risk association from the consumption of contaminated fish was evaluated. Fish samples were collected for period of six months and the pesticide residues analysis was carried out by using QuEChERS method along with conventional method (Hand shaken technique) and gas chromatography with electron capture detector (GC-ECD). (DDTs) and its metabolites were observed with DDD were the predominant contaminants, followed by DDT. The predominance of DDE may be attributed to their current use in vector control and contamination from past usage. The estimated daily intakes (EDIs) of DDT and its metabolites from all fish species were much lower than the acceptable daily intakes (ADIs), indicating that consumption of fish is at little risk to human health at present. However, the cancer risk estimates in the area of concern and the hazard ratios (HRs) of DDTs below the threshold value of one, indicating daily exposure to these compounds is a potential concern.

Biomonitoring of organochlorine pesticides and cancer survival: a population-based study.

Organochlorine pesticides (OCPs) are endocrine-disrupting chemicals (EDCs) that even at very low levels can cause cancer by increasing the activity of tumor cells and suppressing the immune system. There is also little information on OCPs and survival after diagnosis. The aim of this study was to monitor the concentration of OCPs in the blood serum of cancer patients and its relationship with their socio-demographic characteristics and ultimately that impact on survival time and hazard ratio (HR). This cross-sectional study included 89 diagnosed patients with cancer in Isfahan, Iran. 12 types of OCPs were measured in serum by gas chromatography (7GC) with an electron capture detector and equipped with mass spectrometer (MS). Also, participants' questionnaire was completed to collect information. T-test, ANOVA, and Chi-square tests were used to evaluate the association between serum levels of OCPs and quantitative and qualitative information of patients. Survival analysis was also examined based on Kaplan-Meier method, log-rank test, and Cox model. The mean of total OCPs in patients' serum was calculated to be 1.82 ± 1.36μg/L. Concentration of 2,4' DDE had a significant relationship with body mass index (BMI) (kg/m2) (P < 0.05). In addition, gender revealed a significant correlation in estimating survival time (P < 0.05). Non-exposure to OCPs showed a positive effect on increasing the life expectancy of patients. Lindane and endosulfan increased the risk of death by 16% and 37%, respectively, with insignificant P value (P > 0.05). The findings of the present study showed adverse effects of OCPs on patients' survival time and increased mortality of HR. Moreover, as the first research conducted in the study area, it is suggested management of environmental, individual and social factors that could be influenced the biological accumulation of OCPs in humans and cause health promotion.

Groundwater recharge and dating in crystalline basement aquifers of Vea catchment: An integrated environmental tracers’ approach

The crystalline basement aquifers host significant groundwater resources for the communities in Vea catchment for public and irrigational water supply. As part of measures to understand the hydrogeological processes of the area, multi-tracers (SF6, CFC-12, CFC-11, 3H, δ18O and δ2H) were employed to elucidate the groundwater residence time, recharge mechanism and mixing process of the shallow groundwater. Ambient concentrations of these tracers were taken from 10 sampling locations in the Vea catchment of Upper East Region of Ghana. A purge and trap method was used to take the samples and electron capture detector gas chromatography (GC-ECD) was used to analytically measure the SF6 and CFCs gases in the groundwater. The SF6, CFC-11 and CFC-12 dating complimented with 3H revealed that the groundwater age in the catchment was relatively young ranging from 5 to 42 years with a mean age of 23 years. This corroborates well with the stable isotopes data , which showed that the catchment receives modern recharge from meteoric origin. The results also indicated that the estimated SF6 ages were younger compared to the CFCs ages, suggesting additional inputs of SF6 from terrigenous sources. Similarly, a comparison of 3H and CFCs showed little variations in ages in some wells, a possible indication of CFCs degradation. The conceptual groundwater flow model developed showed three groundwater flow regimes along the topographical line. Despite some uncertainties in age interpretations, the multi-environmental tracers have been successfully used to date shallow groundwater in the Vea catchment. To reduce the uncertainties in the age determination, the use multi tracer approach is highly recommended.

First WHO/UNEP survey of the current concentrations of persistent organic pollutants in human milk in Morocco

The presence of persistent organic pollutants (POPs) in human milk is an indicator of the level of these substances in the environment and enables evaluation of the potential exposure of breastfed children. POPs concentrations in a Moroccan human milk pooled sample (59 donors) were determined for the first time by the WHO reference laboratory to provide a baseline and allow monitoring of the future trends for those persistent organohalogen compounds. Eighty-one different POPs, including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and dioxins and furans (PCDD/Fs) were identified and quantified by using gas chromatography (GC) with an electron capture detector (ECD) and confirmed by gas chromatography-mass spectrometry (GC/LRMS). The obtained results showed that the sum of DDT (sum of o,p’-DDD, p,p′-DDD, o,p′-DDE, p,p′-DDE, o,p’-DDT, and p,p′-DDT) was 237.9 ng/g, representing 94.0% of all detected OCPs levels, with a dominance of p,p′-DDE, and p,p′-DDT. Cis-heptachlor epoxide, HCB, and HCH were found at much lower levels. PCB indicator level was 60.7 ng/g of lipid, with the dominance of PCB 138, PCB 153, and PCB 180, presenting 98.3% of the total. Among the 25 PBDE congeners quantified, BDE-47, BDE-153, BDE-197, and BDE-207 were the dominant congeners account for 15.4% of the total concentration of PBDE (1.3 pg/g lipid). The lipid-adjusted level of PCDD/Fs and dl-PCBs expressed in Toxic Equivalents (TEQs: 6.65 pg/g) were lower in comparison to those found in the other countries. In summary, detected POPs levels in Moroccan human milk were much lower compared to the other countries, reflecting the effectiveness of the compliance with Stockholm Convention requirements on eliminating or reducing emissions of selected POPs. Continued monitoring is needed for these compounds, for which this is the first data available, provided by the WHO/UNEP survey in Morocco.

Residual Behavior of Tebuconazole and Trifloxystrobin in Okra Fruits and Soil

ABSTRACT A field trial was conducted to study the dissipation of trifloxystrobin and tebuconazole on okra following application of Nativo (tebuconazole 50% + trifloxystrobin 25% WG) at 350 and 700 g ha−1. The estimation of trifloxystrobin and CGA 321113 residues was carried on gas–liquid chromatograph equipped with electron capture detector and that of tebuconazole on gas chromatograph–mass spectrometry. Average initial deposits of tebuconazole in okra were found to be 0.75 and 1.45 mg kg−1, whereas trifloxystrobin was found to be 0.28 and 0.61 mg kg−1 following the application of Nativo at 350 and 700 g ha−1, respectively. Residues of tebuconazole dissipated below limit of quantification of 0.05 mg kg−1 after 7 and 10 days and of trifloxystrobin after 5 days of last application at recommended and double of the recommended dosages, respectively. For risk assessment studies, theoretical maximum residue contributions (TMRC) were calculated and compared with maximum permissible intake (MPI). It was observed that TMRC values were below MPI in zero day samples at both recommended and double of the recommended dosages. Therefore, the waiting period of 1 day should be observed for safe consumption of okra treated with tebuconazole and trifloxystrobin.

Selectivity and Sensitivity: The Electron Capture Detector (ECD), Its Unique Inventor James Lovelock (1919–2022), and GAIA

The electron capture detector (ECD) is among the original classical detectors for gas chromatography (GC). It is highly selective and sensitive for electron-absorbing compounds, especially those containing halogens. The ECD was developed in the 1960s by James Lovelock (1919–2022), who passed away earlier this year. The ECD is among the early detectors that is used in a relatively unmodified form today. The ECD was crucial in the discovery of chlorofluorocarbons (CFCs) in the upper atmosphere, ultimately leading to the international agreements limiting their use and reducing the ozone hole. In this installment, we review the ECD and its principles of operation and discuss the general tradeoffs in detection between selectivity, ease of use, and sensitivity. We also look at the unique life and work of Lovelock, both inventor of the ECD and one of the earliest scientists to bring attention to climate change through GAIA, which explained his theory that the Earth acts as a massive living organism.

BIOCONCENTRATION OF FENVALERATE INSECTICIDE IN FRESH WATER FISH Channa striatus

Modern agriculture heavily relies on chemicals such as different types of fertilizers, herbicides, fungicides and insecticides. These chemicals have an impact on aquatic organisms Fenvalerate was selected for the study. Channa striatus was selected as a model fish to test the bioconcentration in different organs. C. striatus was collected from a pond far from Kuttanad and transferred to laboratory. 20 healthy fishes were selected for experimental tanks. The fishes were fed with fish meal and rice flour in 1:1 ratio for once every two days. 25% of water were withdrawn from each tank and the pesticide content in the experiment tank was maintained at the same level. Based on the AOAC 2012 standard procedures, the analysis was carried out using a Perkin-model 5890 Gas Chromatography connected with a Ni 63 electron capture detector. The present investigation concludes that the bioconcentration of fenvalerate insecticide affect the gills, liver and muscles of the C. striatus. Insecticide fenvalerate shows a greater sublethal concentration in C. striatus is 0.188906 ppm/1. Fenvalerate is concentrated in the liver, gills and muscle tissues.

Organochlorine pesticides in therapeutic teas and human health risk assessment

ABSTRACT This study evaluated commercially available therapeutic teas for their organochlorine pesticides (OCPs) residue levels to estimate the potential health risks associated with their prolonged consumption. Tea samples that were produced for therapeutic uses were obtained commercially. Organochlorine pesticide residues were extracted from the samples using the modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method and analysed using Gas Chromatography with Electron Capture Detector (GC-ECD). Results showed that the tea samples contained a large number of OCPs residue at levels that were significantly higher than the maximum residue limits (MRLs) set by the European Union (p > 0.05). Aldrin was detected in all samples, methoxychlor, and p,p’-DDT were detected in ≥88% of the samples while γ–HCH, δ–HCH, endosulfan II, and endosulfan sulphate were detected in ≥69% of the samples. Health risk assessment indicated that the highest risk of cancer was associated with aldrin.

Headspace Extraction of Chlorobenzenes from Water Using Electrospun Nanofibers Fabricated with Calix[4]arene-Doped Polyurethane-Polysulfone.

Chlorobenzenes (CBs) are persistent and potentially have a carcinogenic effect on mammals. Thus, the determination of CBs is essential for human health. Hence, in this study, novel polyurethane–polysulfone/calix[4]arene (PU-PSU/calix[4]arene) nanofibers were synthesized using an electrospinning approach over in-situ coating on a stainless-steel wire. The nanosorbent was comprehensively characterized using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR) techniques. The SEM analysis depicted the nanofiber’s unique morphology and size distribution in the range of 50–200 nm. To determine the levels of 1,2,4-trichlorobenzene, 1,2,3-trichlorobenzene, and 1,2,3,4-tetrachlorobenzene in water samples, freshly prepared nanosorbent was employed using headspace-solid phase microextraction (HS-SPME) in combination with gas chromatography micro electron capture detector (GC-µECD). Other calixarenes, such as sulfonated calix[4]arene, p-tert-calixarene, and calix[6]arene were also examined, and among the fabricated sorbents, the PU–PSU/calix[4]arene showed the highest efficiency. The key variables of the procedure, including ionic strength, extraction temperature, extraction duration, and desorption conditions were examined. Under optimal conditions, the LOD (0.1–1.0 pg mL−1), the LDR (0.4–1000 pg mL−1), and the R2 > 0.990 were determined. Additionally, the repeatability from fiber to fiber and the intra-day and inter-day reproducibility were determined to be 1.4–6.0, 4.7–10.1, and 0.9–9.7%, respectively. The nanofiber adsorption capacity was found to be 670–720 pg/g for CBs at an initial concentration of 400 pg mL−1. A satisfactory recovery of 80–106% was attained when the suggested method’s application for detecting chlorobenzenes (CBs) in tap water, river water, sewage water, and industrial water was assessed.

Superhydrophobic Nanosilica Decorated Electrospun Polyethylene Terephthalate Nanofibers for Headspace Solid Phase Microextraction of 16 Organochlorine Pesticides in Environmental Water Samples.

A new solid phase micro extraction (SPME) fiber coating composed of electrospun polyethylene terephthalate (PET) nanofibrous mat doped with superhydrophobic nanosilica (SiO2) was coated on a stainless-steel wire without the need of a binder. The coating was characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectrometer (FTIR) techniques and it was used in headspace-SPME of 16 organochlorine pesticides in water samples prior to gass chromatography micro electron capture detector (GC-µECD) analysis. The effects of main factors such as adsorption composition, electrospinning flow rate, salt concentration, extraction temperature, extraction time, and desorption conditions were investigated. Under the optimum conditions, the linear dynamic range (8–1000 ng L−1, R2 > 0.9907), limits of detection (3–80 ng L−1), limits of quantification (8–200 ng L−1), intra-day and inter-day precisions (at 400 and 1000 ng L−1, 1.7–13.8%), and fiber-to-fiber reproducibility (2.4–13.4%) were evaluated. The analysis of spiked tap, sewage, industrial, and mineral water samples for the determination of the analytes resulted in satisfactory relative recoveries (78–120%).

Research and development of an air sampling tube for chlorobenzene compounds and its supporting determination method

Objective: To establish a GDH-3 air sample tube for simultaneous determination of twelve kinds of chlorobenzene compounds (CBs) in workplace air by gas chromatography. And to established a matching determination method. Methods: In October 2020, the vapor and aerosol CBs in workplace air were collected by GDH-3 air sampling tube, and desorption and elution with 3.00 ml toluene for 15 min, then the solution separated by DB-23 capillary column, and finally detected with microcell electron capture detector. Results: The quantitative determination ranges of twelve isomers of CBs were 0.71×10(-3)-2000.00 mg/L, with the correlative coefficients were 0.99967-0.99998. The minimum detectable concentrations were 0.04-112.63 μg/m(3), and the minimum quantification concentrations were 0.14-375.42 μg/m(3) (15.00 L sample, 3.00 ml sample solution) . The average elution efficiencies were 96.00%-104.00%. The within-run relative standard deviations (RSDs) were 2.54%-6.12%, and the between-run RSDs were 3.85%-7.87%. Sealed samples could be stable at room temperature for at least 15 days. Conclusion: GDH-3 air sample tube can be used for simultaneous determination of twelve kinds of CBs in workplace air by gas chromatography. The established supporting measurement method meets the measurement requirements of the occupational health standard detection method, and the it's suitable for the simultaneous determination of 12 kinds of CBS in the air.

Seasonal congener survey for polychlorinated biphenyls in sediments of south-western rivers, Nigeria: Occurrence, sources, and ecotoxicological risks

In this work, sediment samples from major rivers within southwestern Nigeria were collected to study the seasonal distribution, transport, and ecological risk assessment of polychlorinated biphenyls (PCB) using gas chromatography coupled with an electron capture detector (GC–ECD). The ΣPCB concentrations ranged from 9.86–77.56 μg/kg and 11.88–80.76 μg/kg in dry and wet seasons respectively. The most predominant PCBs congener in all the sediments was 2,2’,4,5,5’-PeCB(#101) with mean concentrations of 4.35 ± 2.96 and 6.10±3.38μg/kg across all locations in dry and wet seasons respectively. Relevant guidelines including sediments quality guidelines (SQGs) mean effect range-median quotient (m-ERM-Q), and toxic equivalent factor (TEF) were used for risk assessment and to evaluate the ecological risks of PCBs across the rivers. The toxic equivalent quantity (TEQ) ranged from 0.044–0.807 μg-TEQ/kg and 0.055–0.825 μg-TEQ/kg for the dry and wet seasons respectively. The non-ortho PCBs congeners constituted ≥ 99.8% of the ∑TEQ values. The seven indicators PBCs for evaluating non-dioxin-like PCBs ranged from 3.70–32.69 μg/kg across the seasons and accounted for 33.4%, 39.8%, 36.8%, 37.9%, 41.4%, and 40.4% of the ∑PCBs at Asejire, Odo Ona, Ogbese, Ogun, Ikorodu rivers and Third Mainland Bridge Ocean respectively. In two out of six rivers, the ∑PCBs exceeded the Canadian SQG threshold effect level of 21.5 and 34.1μg/kg for fresh and marine sediments respectively. The results of the study call for a concerted effort toward holistic monitoring of PCB residues in rivers in Nigeria to ensure ecological integrity and the protection of human health.

Organochlorine pesticides residue affinity in fish muscle and their public health risks in North West Ethiopia.

Pesticides are the parent compounds, their metabolites, and associated impurities of agricultural and health chemical inputs. If they are found at concentration levels higher than the standard limits, they have potential negative impacts on the ecosystem in general and on fish and humans in particular. This study investigates organochlorine pesticides (OCPs) residue occurrences in fish muscle and assesses their public health potential risks, in North West Ethiopia. The concentration of OCPs residue under gas chromatography with electron capture detector (GC-ECD) was detected in 37.84% of fish muscle samples. The mean amounts detected were Endosalfan I, 341.50 ± 32.19 μg/kg; Endosalfan II, 36.01 ± 2.3μg/kg; Endosalfan sulfate, 5.43 ± 4.06 μg/kg; 4, 4, DDE (4,4-dichlorodiphenyldichloroethylene), 64.01 ± 9.08 μg /kg; 4,4, DDD (4,4-dichlorodiphenyldichloroethane), 5.65 ± 3.12 μg/kg; and 4, 4, DDT (4,4-dichlorodiphenyltrichloroethane), 1.58 ± 0.30 μg/kg. The mean concentration of Endosalfan I tested in fish muscle samples was higher than that of the permissible limit of different international standards. However, due to the low per capita consumption rate of fish origin food in Ethiopia, the health risk index (HRI) ranges from 0.002 to 0.1275, which shows there is no public health risk. This study highlights the possibility of chemical residue occurrence in fish food products, and hence pesticide use regulations and monitoring concentration levels should be implemented regularly to avoid human and environmental health risks.

Lindane bioremediation by Paenibacillus dendritiformis SJPS-4, its metabolic pathway analysis and functional gene annotation

Lindane, hexachlorohexane is an organic persistent pesticide reaches the water bodies via agricultural waste water runoff or rainfall. The present study shows the lindane bioremediation potential of Paenibacillus dendritiformis SJPS-4 and its degradation potential which was evaluated using gas chromatography 7890A equipped with HP-5 column and electron capture detector (μECD). Further, the effect of whole cell immobilization resulted the lindane degradation of 80.72% in mineral salt medium (MSM-L) with significant degradation after immobilization of bacterial cells in alginate beads and agar cubes. The functional gene annotation using KEGG-KASS tools revealed the metabolic pathway for lindane degradation involving lin genes (lin A, lin E, lin B, lin X, lin C, lin D) acting on subsequent compound at each step including the subsequent metabolites in the pathway were utilized. This study gives the new insights on the potential of naturally occurring bacteria Paenibacillus dendritiformis SJPS-4 towards its role in decontaminating such environments.

Monitoring of Heavy Metals and Pesticide Residues of Herbal Decoctions in Traditional Korean Medicine Clinics in Korea.

In this study, we investigated whether the levels of heavy metal and pesticide residues in herbal decoctions in Korea in 2019 were within normal limits. In total, 30 decoctions composed of multi-ingredient traditional herbs were sampled from traditional Korean medicine (TKM) clinics, TKM hospitals, and external herbal dispensaries in 2019. The decoctions were analyzed for heavy metal content such as lead, arsenic, and cadmium using inductively coupled plasma optical emission spectrometry. For mercury, an automatic mercury analyzer based on the gold amalgamation process was used. For pesticide residues, gas chromatography with electron capture detection and gas chromatography with mass selective detection were used for the analyses. Based on the testing, heavy metals were identified in most of the decoctions (Cd: 0.000–0.003 ppm, Pb: 0.003–0.023 ppm, As: 0.000−0.016 ppm, Hg: 0.000–0.002 ppm). Pesticide residues (e.g., total DDT, total BHC, aldrin, endrin, dieldrin) were not detected at all. All of these were no more than the limit values in preceding studies. Therefore, this study confirms that the contents of heavy metals and pesticides in herbal decoctions are within safe levels based on a previous study and provides evidence for establishing safety management standards for herbal decoctions in Korea.

Risk assessment of organophosphorus pesticide residues in drinking water resources: Statistical and Monte-Carlo approach

A large part of the world's agricultural production, despite its adverse effects on human health and water resources, depends on the use of pesticides. Despite strict regulations, the use of pesticides continues around the world. This study aimed to determine the residual concentrations of malathion and diazinon in samples of drinking water resources. To achieve this goal, 384 samples from 8 various sites from January to December 2020 were analyzed using gas chromatography (GC) with an electron capture detector (ECD) and liquid-liquid extraction technique. Besides, statistical analysis and a risk-modeling approach supported by an automatic Monte-Carlo procedure were applied. The results showed that there is a high carcinogenic risk regarding malathion and that the low age population is at the most non-carcinogenic risk regarding diazinon.