Electron-Capture Detector

For nearly a century, nuclear physics has advanced through two parallel traditions: the shell model, which catalogs patterns in spectra and stability, and the liquid drop model, which describes bulk behavior through analogy. Both have been remarkably successful, yet both share a quiet limitation: neither reveals why the nucleus exhibits the patterns it does. Magic numbers, deformation, rigidity, fission pathways, and the evolution of shells across the chart of nuclides remain empirical regularities rather than structural consequences.
The proton–neutron HEX model began as an attempt to answer a simple question:
What if the nucleus is not a cloud of interacting particles,
but a geometric object?
If protons and neutrons form a coordinated lattice rather than a statistical ensemble, then the familiar regularities of nuclear behavior should not be coincidences. They should be the inevitable outcomes of symmetry, topology, and discrete structural rules. This work explores that possibility. It proposes that the nucleus is built from a rigid proton backbone and three sequenced neutron helices whose geometry determines everything the nucleus can be.
The goal of the HEX framework is not to replace existing models, but to reveal the structural foundation beneath them? to show that the patterns long treated as empirical inputs may instead be the natural consequences of a deeper architectural order. If the nucleus is a structure, not a swarm, then its behavior is not mysterious. It is geometry.
Unlike traditional approaches, which rely on differential equations, parameterized potentials, and large scale numerical fits, the HEX framework replaces heavy mathematics with simple geometry. The nucleus is not modeled through abstract operators or effective forces, but through the discrete rotational closures, tiling rules, and rigidity constraints of a physical scaffold. Where conventional models infer structure from mathematical behavior, HEX derives behavior from structural necessity. The complexity of nuclear phenomena emerges not from complicated equations, but from the combinatorics of a few geometric rules.
The result is a unified structural picture in which stability, deformation, and fissility follow directly from geometry, not phenomenology. The HEX model therefore provides a predictive, testable, and architecturally coherent foundation for nuclear physics, one that explains long standing empirical regularities and offers clear guidance for the exploration of neutron rich isotopes, superheavy elements, and nucleosynthetic pathways.
Together with the first HEX paper -  https://doi.org/10.5281/zenodo.13336683 -
this work completes a structural framework in which nuclear stability, deformation, and energetics arise from geometry alone. The resulting picture is predictive, testable and internally coherent, offering a geometric roadmap for the nuclear landscape.

For nearly a century, nuclear physics has advanced through two parallel traditions: the shell model, which catalogs patterns in spectra and stability, and the liquid drop model, which describes bulk behavior through analogy. Both have been remarkably successful, yet both share a quiet limitation: neither reveals why the nucleus exhibits the patterns it does. Magic numbers, deformation, rigidity, fission pathways, and the evolution of shells across the chart of nuclides remain empirical regularities rather than structural consequences.
The proton–neutron HEX model began as an attempt to answer a simple question:
What if the nucleus is not a cloud of interacting particles,
but a geometric object?
If protons and neutrons form a coordinated lattice rather than a statistical ensemble, then the familiar regularities of nuclear behavior should not be coincidences. They should be the inevitable outcomes of symmetry, topology, and discrete structural rules. This work explores that possibility. It proposes that the nucleus is built from a rigid proton backbone and three sequenced neutron helices whose geometry determines everything the nucleus can be.
The goal of the HEX framework is not to replace existing models, but to reveal the structural foundation beneath them? to show that the patterns long treated as empirical inputs may instead be the natural consequences of a deeper architectural order. If the nucleus is a structure, not a swarm, then its behavior is not mysterious. It is geometry.
Unlike traditional approaches, which rely on differential equations, parameterized potentials, and large scale numerical fits, the HEX framework replaces heavy mathematics with simple geometry. The nucleus is not modeled through abstract operators or effective forces, but through the discrete rotational closures, tiling rules, and rigidity constraints of a physical scaffold. Where conventional models infer structure from mathematical behavior, HEX derives behavior from structural necessity. The complexity of nuclear phenomena emerges not from complicated equations, but from the combinatorics of a few geometric rules.
The result is a unified structural picture in which stability, deformation, and fissility follow directly from geometry, not phenomenology. The HEX model therefore provides a predictive, testable, and architecturally coherent foundation for nuclear physics, one that explains long standing empirical regularities and offers clear guidance for the exploration of neutron rich isotopes, superheavy elements, and nucleosynthetic pathways.
Together with the first HEX paper -  https://doi.org/10.5281/zenodo.13336683 -
this work completes a structural framework in which nuclear stability, deformation, and energetics arise from geometry alone. The resulting picture is predictive, testable and internally coherent, offering a geometric roadmap for the nuclear landscape.

For nearly a century, nuclear physics has advanced through two parallel traditions: the shell model, which catalogs patterns in spectra and stability, and the liquid drop model, which describes bulk behavior through analogy. Both have been remarkably successful, yet both share a quiet limitation: neither reveals why the nucleus exhibits the patterns it does. Magic numbers, deformation, rigidity, fission pathways, and the evolution of shells across the chart of nuclides remain empirical regularities rather than structural consequences.
The proton–neutron HEX model began as an attempt to answer a simple question:
What if the nucleus is not a cloud of interacting particles,
but a geometric object?
If protons and neutrons form a coordinated lattice rather than a statistical ensemble, then the familiar regularities of nuclear behavior should not be coincidences. They should be the inevitable outcomes of symmetry, topology, and discrete structural rules. This work explores that possibility. It proposes that the nucleus is built from a rigid proton backbone and three sequenced neutron helices whose geometry determines everything the nucleus can be.
The goal of the HEX framework is not to replace existing models, but to reveal the structural foundation beneath them? to show that the patterns long treated as empirical inputs may instead be the natural consequences of a deeper architectural order. If the nucleus is a structure, not a swarm, then its behavior is not mysterious. It is geometry.
Unlike traditional approaches, which rely on differential equations, parameterized potentials, and large scale numerical fits, the HEX framework replaces heavy mathematics with simple geometry. The nucleus is not modeled through abstract operators or effective forces, but through the discrete rotational closures, tiling rules, and rigidity constraints of a physical scaffold. Where conventional models infer structure from mathematical behavior, HEX derives behavior from structural necessity. The complexity of nuclear phenomena emerges not from complicated equations, but from the combinatorics of a few geometric rules.
The result is a unified structural picture in which stability, deformation, and fissility follow directly from geometry, not phenomenology. The HEX model therefore provides a predictive, testable, and architecturally coherent foundation for nuclear physics, one that explains long standing empirical regularities and offers clear guidance for the exploration of neutron rich isotopes, superheavy elements, and nucleosynthetic pathways.
Together with the first HEX paper -  https://doi.org/10.5281/zenodo.13336683 -
this work completes a structural framework in which nuclear stability, deformation, and energetics arise from geometry alone. The resulting picture is predictive, testable and internally coherent, offering a geometric roadmap for the nuclear landscape.

The misuse of agricultural chemicals poses signifcant risks to public health, particularly in countries like Ethiopia where farming practices may not adhere to recommended safety measures. This review examines the challenges associated with agricultural pesticide residue risks in Ethiopia and explores strategies to promote preharvest interval adherence among farmers. Drawing on existing literature, the review discusses the impacts of pesticide residues on human health, factors infuencing farmer behavior regarding pesticide application and harvesting practices, and potential socioeconomic implications of improving pre-harvest interval compliance. Furthermore, the review highlights successful interventions and policy measures implemented in other contexts to enhance farmer awareness, training, and access to safer agricultural practices. In Ethiopia, most farmers lack proper pesticide knowledge, with none able to accurately identify or apply preharvest interval guidelines. They also handle pesticides without protective gear and spray pesticides more than a dozen times per growing season, increasing the risk of nonadherence to PHI. As a result, detectable pesticide residues are found in fruits and vegetables, with samples showing measurable levels and some even exceeding international maximum residue limits, leading to export rejections. Strengthened extension services, stricter oversight of agrochemical distributors, and municipal-level monitoring systems are essential to mitigate food-safety risks and protect agricultural market access. By synthesizing evidence of pesticide residues, this review aims to inform policymakers, agricultural extension services, and relevant stakeholders about the importance of promoting adherence to the preharvest interval as a crucial step toward mitigating agricultural chemical residue risks and protecting public health in Ethiopia.

This review addresses the environmental impact of dichlorodiphenyltrichloroethane (DDT), with an emphasis on its origin, monitoring techniques, pollution tactics, and human health consequences. DDT, a persistent organic pollutant, has been extensively used in agriculture and public health, resulting in its broad dispersion in numerous environments. This study examined the basic causes of DDT pollution, including historical use, agricultural runoff, and incorrect disposal procedures. Furthermore, this study investigated solutions for reducing DDT contamination, including regulatory measures, alternative pest control tactics, and safe disposal procedures. The effects of DDT exposure on human health, including its association with cancer, reproductive abnormalities, and neurological damage, have also been investigated. Overall, this study emphasizes the significance of continued efforts to monitor and reduce DDT pollution in order to protect human health and the environment.

The aim of this study was to assess the suitability of the perirenal fatty tissue for the determination of an organochlorine pesticide. Fatty tissue samples were prepared by the matrix solid phase dispersion (MSPD) method, and pesticide levels were determined by gas chromatography on capillary column using an electron capture detector. Results were confirmed by gas chromatography/mass spectrometry (GC/MS) system. The results showed that the perirenal fatty tissue contained significantly higher levels of hexachlorobenzene (HCB) than the dorsal fatty tissue (P < 0.01). All the levels were below the criteria for maximum residue limits established by Croatia and the EU.

Small flux chambers are widely used to measure emissions of nitrous oxide, N 2 O , from soil, the gas being determined by gas chromatography with an electron capture detector. The technique is relatively cheap, and is adaptable to a wide range of site conditions and emission rates: from the order of 1 µg m -2 h -1 to more than 10 mg m -2 h -1 . Increasingly, systems are being automated, to get more information on short-term temporal variability and to collect data over long periods to improve estimates of total annual emissions. Such systems are being used in the field and with soil monoliths installed in a greenhouse. Large chambers 50-60 m 2 in area, with gas analysis by long-path infrared spectrometry, offer a way of overcoming small-scale spatial variability, and are useful in conditions where micrometeorological methods may not be applicable, or when long runs of data are needed from the same site. In studies with small closed chambers, we have measured N 2 0 emissions from gra...

The study involved the use of soxhlet apparatus and CP-3800 Gas Chromatograph equipped with a 63Ni electron capture detector to investigate the presence and levels of organochlorine pesticide (OCP) residues in sampled parts of watermelon. The study revealed the presence of fifteen OCPs residues in the peel, pulp and seeds of watermelon from the selected communities in the Ada-West District of the Greater Accra Region of Ghana. Most of the OCP residues investigated were below the limit of detection of 0.01 µg/kg. Detectable OCP residues whose concentrations were above detection limit were dieldrin and p, p’-dichlorodiphenyldichloroethene (p,p&#39;–DDE). The seeds of watermelon from Koluedor recorded the highest level of 2.10 µg/kg of p’p-DDE while the lowest level of 0.20 µg/kg of dieldrin and p’p-DDE were recorded in the peel of watermelon from Sege. The mean levels of the detected pesticide residues in peel, pulp and seeds of watermelon were also below maximum residue limits (MRLs)...

A Gas Chromatography (GC) methodology has been validated for the determination of some halogenated pesticides. Complete separation of the pesticide prepared in ethyl acetate was achieved on Rtx - 1 column with dimension, 30m x 0.25mm x 0.25:m. The GC equipped with electron capture detector was run using column temperature programmed from 80ºC (2 min) to 200ºC (15 min) at the rate of 4ºC/min giving a total analysis time of 47 min. The detector and injector were respectively at temperatures of 300 and 225ºC. The method was validated with respect to precision in terms of reproducibility of retention times and peak heights, linearity and minimum detectable quantity of the pesticides. Under the operated GC conditions, diuron eluted first while heptachlor epoxide was the last to elute. The chromatographic detector was more sensitive to &quot;-endosulfan and $-endosulfan with Minimum Detectable Quantity (MDQ) of 0.002 ng. The detector was however, less sensitive to captan with MDQ of 0.08 ...

Agricultural activity in the state of Sonora is well known as one of the most developed in the country. It is high-tech and highly productive, and brings in a large amount of foreign currency. To continue supplying the national and international markets’ high demand for produce, intensive cultivation has been necessary, and heavy use of agrochemicals has resulted in soil pollution. Organochlorine pesticides (OCPs) were used from l950 to 1991, mainly on cotton crops. In industrialized countries these pesticides were banned or restricted in 1970 and they have been banned in Mexico since 1991.These agrochemicals are harmful to human health as well as to the environment due to their toxicity and volatility, and because they accumulate and persist in the soil. For this reason, countries participating in the Stockholm Convention agreed to reduce or eliminate their use. The objective of this work was to verify the presence of OCPs in the main agricultural areas (North and Central) of the s...

A suite of gaseous perfluorocarbon (PFT) conservative tracers were successfully employed to monitor migration of the CO 2 plume during the Frio Brine Pilot Test. The conservative tracers enabled quantification of plume breakthrough and transport times, added value to model validity testing, and are providing insight into the saturation behavior of the CO 2 plume. Specific pairs of tracers were introduced at chosen times alongside the injected CO 2 stream. These tracers were transported through the formation and then collected at a monitoring well approximately 30 meters up-dip. A novel U-tube design allowed for high frequency sampling at the monitoring well. The PFTs introduced at the onset of CO 2 injection appeared at the monitoring well 50.3 hours after injection and coincided with the initial CO 2 breakthrough. A second and third set of PFT pairs were introduced 102 and 120 hours after the initial CO 2 injection. The breakthrough times for the second (51.7 hours) and third (51.2 hours) PFT sets indicated little change in the overall saturation of the CO 2 plume, between the injection and monitoring location. The rapid establishment of well developed flow paths demonstrates the importance in understanding preferential flow for assessing the storage efficiency of geologic CO 2 sequestration sites.

Silver fish (Rastreneobola argentea) samples from Lake Victoria and Lake Kyoga were analyzed for dichloro-diphenyl-trichloroethane (DDT) and metabolites using a Gas Chromatograph equipped with an Electron Capture Detector. Confirmation of results was by Gas Chromatography equipped with Mass Spectrophotometer (GC-MS). DDT and metabolites were detected in 90% of the total samples (63 out of 70). pp' DDT was the most frequently detected residues in the samples whereas op' DDE was detected in none of the samples. The mean ΣDDT concentrations in fish from Lake Victoria varied from 0.147 to 0.396 µg/kg while that in Lake Kyoga varied from 0.207 to 0.506 µg/kg dry wt of fish sample. The concentration of total DDT in the fish samples ranged from 0.147 to 0.506 µg/kg dry wt. This was far below the recommended FAO limit of 5000 µg/kg for fish (edible portion), implying that the fish are safe for human consumption.

Single and multiple plumes of sulphur hexafluoride were measured and mapped using a prototype open-path Fourier transform infrared spectrometer (OP-hl iR)-computed tomography (CT) system in an indoor exposure chamber. The OP-FTCR-CT system accurately mapped the position of concentration peaks at different locations in the chamber, and estimated concentrations within a range of 4-50% when compared with point samples measured by gas chromatography with an electron capture detector. Two OP-FTTR spectrometer ray configurations, one with 100 rays and the other with 136 rays, were used to scan the chamber and reconstruct the concentration maps. Ray configuration and time to scan the entire chamber were found to have a profound effect on the quality of the reconstructed maps. The ability to obtain real-time, non-invasive measurement!, and to generate spatially and temporally resolved maps of multiple chemicals, makes the OP-FTIR-CT system a promising technique for monitoring source emissions and evaluating exposures to air contaminants in a workplace.

Single and multiple plumes of sulphur hexafluoride were measured and mapped using a prototype open-path Fourier transform infrared spectrometer (OP-hl iR)-computed tomography (CT) system in an indoor exposure chamber. The OP-FTCR-CT system accurately mapped the position of concentration peaks at different locations in the chamber, and estimated concentrations within a range of 4-50% when compared with point samples measured by gas chromatography with an electron capture detector. Two OP-FTTR spectrometer ray configurations, one with 100 rays and the other with 136 rays, were used to scan the chamber and reconstruct the concentration maps. Ray configuration and time to scan the entire chamber were found to have a profound effect on the quality of the reconstructed maps. The ability to obtain real-time, non-invasive measurement!, and to generate spatially and temporally resolved maps of multiple chemicals, makes the OP-FTIR-CT system a promising technique for monitoring source emissions and evaluating exposures to air contaminants in a workplace.

Single and multiple plumes of sulphur hexafluoride were measured and mapped using a prototype open-path Fourier transform infrared spectrometer (OP-hl iR)-computed tomography (CT) system in an indoor exposure chamber. The OP-FTCR-CT system accurately mapped the position of concentration peaks at different locations in the chamber, and estimated concentrations within a range of 4-50% when compared with point samples measured by gas chromatography with an electron capture detector. Two OP-FTTR spectrometer ray configurations, one with 100 rays and the other with 136 rays, were used to scan the chamber and reconstruct the concentration maps. Ray configuration and time to scan the entire chamber were found to have a profound effect on the quality of the reconstructed maps. The ability to obtain real-time, non-invasive measurement!, and to generate spatially and temporally resolved maps of multiple chemicals, makes the OP-FTIR-CT system a promising technique for monitoring source emissions and evaluating exposures to air contaminants in a workplace.

A sensitive, rapid, and simple multiresidue method for the simultaneous determination of 19 pesticides in different varieties of lettuce (Lactuca sativum) was developed. Lettuce samples were extracted by homogenization with acetone and partitioned into ethyl acetatecyclohexane. Subsequent sample cleanup was not needed. Final determination was made by capillary gas chromatography (GC) with electron-capture detection (ECD). Confirmation analysis of pesticides was performed by GC coupled with mass spectrometry in the selected ion monitoring mode. The average recovery by the GCECD method obtained for these compounds varied from 66.4 to 119.2 with relative standard deviations &lt;7.7. The GCECD method has good linearity, and the detection limit for the pesticides studied varied from 0.1 to 3.8 g/kg. The proposed method was used to determine pesticide levels in different types of lettuce grown in soils from experimental fields.

A liquid-gas-phase tubing separator was designed and its operation studied in comparison with a PTFE tape-based separator. The relative efficiencies of the two separators were compared after injection into the carrier solution of a sample containing free chlorine using a chromatographic electron-capture detector for detection in the gaseous phase. The membrane separator contained porous PTFE tape whereas the tubular separator consisted of microporous PTFE membrane tubing. The two separators were compared with respect to sensitivity and reproducibility, simplicity of design and liability to interferences. Linear ranges and free chlorine detection limits were established for each of the two separators, that of the PTFE tape-based separator being 100 pg 1-l and that of the tubing device 50 gg 1-l.

A multi-residue method was developed to determine different types of pesticides in soils. An extraction with pressure and temperature, through accelerated solvent extraction (dichloromethane:acetone, 50:50, v/v). The pesticides were determined by gas chromatography with several selective detectors: electron capture detector, pulsed flame photometric detector and thermionic specific detector. The following parameters were determined: limit of detection, limit of quantification, equipment linearity (working interval), method linearity as well as, method accuracy and precision. The average recoveries ranged between 76 and 106%, with the exception of chlorothalonil, which had an average recovery of 46%. Additionally, detection limits from 0.9 to 7.6 ng g -1 and the quantification limits from 3.00 to 25.47 ng g -1 were estimated. In terms of linearity and precision, the results obtained were in the ranges considered adequate (R 2 ≥ 0.98 and coefficient of variation (CV) ≤ 20%), with the exception of aldrin (R 2 = 0.946, CV = 35.79%), lindane (R 2 = 0.917, CV = 32.91%) and chlorothalonil (R 2 = 0.8184, CV = 81.35%). The proposed method was used to evaluate pesticides in real soil samples, detecting concentrations over 1000 ng g -1 for some pesticides. The method was correctly validated and provided for the rapid determination of pesticides in soil.

This work is proposed to investigate pesticide residues in chicken eggs in El-Sharkia Province, Egypt. Analysis of pesticide residues was performed on 120 egg samples included 80 random edible egg samples (40 farm and 40 home produced hen eggs) and other 40 unhatched eggs. Edible eggs were collected from different stores, places and supermarkets. unhatched incubated eggs were collected from different hatcheries during the winter season. Organochlorine pesticides (OCPs) and organophophorous insecticides (OPIs) residue analysis of samples was done using Agilent Gas chromatograph (GC) Model 6890 N. The results revealed presence of OPIs in higher concentration in home produced eggs than that in farm produced eggs, while OCPs present in farm produced egg in higher levels than that in home produced one. Unlike other studies we have not found higher levels of exposure for most pesticides in those consumers choose home produced eggs, and even farm produced eggs. Regarding unhatched eggs dimethioate recorded the highest concentration which exceeded Maximum Residual Limits (MRLs) of (0.05) mg/kg in all the examined samples. None of the other detected pesticide residues exceeded (MRLs). It was concluded that the levels of pesticide residues in edible eggs either home or farm produced eggs should not exceed Accepted Daily Intake (ADI) established by the World Health Organization (WHO) Joint Meeting on Pesticide Residues Report ( JMPR). The study suggests the need for further investigations to determine toxic mechanisms by which dimethoate distress chick emberyos at different developmental stages and result in hatching failure.

In this study, levels of polycyclic aromatic hydrocarbons (PAH), aliphatic hydrocarbons (n-alkanes) and volatile hydrocarbons were determined in water samples of the port of Vlora which is the second largest port in Albania. It is located in Vlora Bay, near Vlora city. Presence of these pollutants in port area is mainly because of ships transport, commercial/passengers processing and the water currents in-side/out-side the port area. Hydrocarbons (PAHs, n-alkanes and BTEX) are generated mainly by the transport (automobiles, ships, trains, etc), extracting/processing of oil industry, coal mine and other industries. Forest burning and their natural background make them very often in environment. Water samples were taken in May 2022 in different stations of the Vlora&#39;s port (inside and outside its area). Aromatic and aliphatic hydrocarbons were extracted simultaneously using two steps liquid-liquid extraction (LLE) technique. Firstly, dichloromethane (MeCl2) and after that n-hexane...

This preliminary study presents first data on organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) concentrations in water and sediment samples of Devolli River. It is located in Southeast Albania, in Korca field, which is the second agricultural area in Albania. Sampling stations water of Devolli River were selected in eight different stations, starting from its stream (Gramozi Mountain) to the end of Korca field, near Banja hydropower (Gramshi region). Sampling of water and sediments were done in the same stations, in December 2018. Pesticides were used in the past in this area for many years mainly for agricultural purposes. Also, basin of Devolli River is affected from industrial activity and urban pollution, too. Water irrigation and rainfall contribute on their transport from soil to underground and surface waters. Organochlorine pesticides and PCB are very stable compounds that can be found in the environment for many years after their application. Liquid-liq...

In this paper are presented concentrations of organochlorinated pesticides and polychlorinated biphenyls in sediment samples of Patoku Lagoon. Fifteen sediment samples were taken in different stations of lagoon using Van Veen grab standard sampler. Sediment samplings were done in October 2013. Ultrasonic extraction was used for extracting pesticide residues from fraction sediment samples of Patoku Lagoon. Hexane/Dichloromethane (3:1) mixture used as extracting solvent. Clean-up procedure was performed using firstly metallic mercury followed a second clean-up procedure in an &quot;open&quot; florisil column. The organochlorine pesticides detected were HCHs (a-, b-, γ- and d-isomers) and the DDT-related chemicals (o,p-DDE, p,p-DDE, p,p-DDD, p,p-DDT), hexachlorobenzene (HCB), Heptachlor, Heptachlorepoxide, Aldrine, Dieldrine, Endrine, Methoxychlor and Mirex. Seven PCB markers were analyzed for evaluation of PCB concentrations in sediment samples. Analyses were done with capillary colum...

This study presents concentrations of organochlorine pesticides and their residues in some water ecosystems of Albania. The water samples were collected in three ports of Adriatic Sea (Ports of Vlora, Durres and Porto-Romano), in four rivers (Semani, Shkumbini, Erzeni and Mati rivers) and two main lagoons of Albania (Karavasta and Patoku lagoons). 117 water samples were analyzed for a two years period (March 2014 -April 2016). Qualitative and quantitative analyze of 31 organochlorine pesticides and their residues based on EPA 8081B Method were realized using technique of gas chromatography with electron capture detector. RTX-5 capillary column was used for separation of organochlorine compounds. The higher concentrations of organochlorine pesticides were found for water samples of Shkumbini River, Semani River and Karavasta Lagoon because of their previous use. Residues of pesticides were in higher level than pesticides because degradation processes. Some individual pesticides were found in higher concentrations in some stations. This could be because of punctual sources or recent use for these pesticides. Organochlorine pesticides concentrations were found to be in lower levels than reported data on previous studies for the same stations.

This study presented data about concentrations of some organic pollutants in two main rivers of Tirana city: Lana River that crosses through the city and Tirana River that lies in northeast of the city. Twenty stations were analyzed in this study. Sampling of water was realized in July 2016. These rivers present important aquatic areas of Tirana region in Albania. For both water river samples were analyzed organochlorine pesticides (OCPs), their degradation products, polychlorinated biphenyls (PCBs), BTEX (benzene, toluene, ethylbenzene and o-, m-, p-xylenes) and polyromantic hydrocarbons (PAH). For extraction of OCPs and PCBs by water samples were used liquid-liquid (LLE) extraction and n-Hexane as extracting solvent. After clean-up and concentration procedures for all samples were performed gas chromatographic analyzes using Rtx-5 capillary column (30 m x 0.33 mm x 0.25 um) and electron capture detector (GC/ECD). were used. The extracts were concentrated and then were injected in gas chromatograph. The analysis of BTEX and PAH in water samples was performed by gas chromatography technique using flame ionization detector (GC/FID). Injections of BTEX were done directly by using Head-Space mode of Polydimethyl Siloxane fiber. VF-1ms capillary column (30 m x 0.33 mm x 0.25 um) was used for separation of BTEX and PAH compounds. The higher concentrations of organochlorine pesticides and PCBs were found for water samples of Tirana River because of their previous use, in the agricultural areas near the basin of this river. The higher concentrations were for volatile PCBs because of their atmospheric deposition in Albanian territory. Relatively high concentrations of BTEX and more volatile PAH compounds were detected in water samples of Lana River. The presence of volatile organic pollutants could be mostly of automobilist transport near the stations, discharging of wastes from some gas stations or some mechanical industries neat the river.

The findings reported here are part of a study that determines concentrations and distribution of organchlorined pesticides, PCBs and PAHs in the water samples of Shkumbini River. Water samples were taken in two periods, February and May 2013 in eleven stations of river, starting at Librazhdi Town up to Shkumbini river mouth in Adriatic Sea. Liquid-liquid extraction with n-Hexane solvent was used for extraction of organochlorinated pesticides (OCPs), their residues and polychlorinated biphenyls (PCBs) from water samples. Clean-up procedure was performed firstly with sodium sulphate (anhydrous) for water removing followed by clean-up procedures with Florisil column for. The organchlorine pesticides detected were HCB, HCHs (alpha-, beta-, gama- and delta- isomers), the DDT-related chemicals (p,p-DDE, p,p-DDD, p,p-DDT), Aldrines (Aldrine, Dieldrine, Endrine) and Heptachlors. Analyses of PCBs was based on the determination of the seven PCB markers (IUPAC Nr. 28, 52, 101, 118, 138, 153 a...

The study involved the use of soxhlet apparatus and CP-3800 Gas Chromatograph equipped with a 63Ni electron capture detector to investigate the presence and levels of organochlorine pesticide (OCP) residues in sampled parts of watermelon. The study revealed the presence of fifteen OCPs residues in the peel, pulp and seeds of watermelon from the selected communities in the Ada-West District of the Greater Accra Region of Ghana. Most of the OCP residues investigated were below the limit of detection of 0.01 µg/kg. Detectable OCP residues whose concentrations were above detection limit were dieldrin and p, p’-dichlorodiphenyldichloroethene (p,p&#39;–DDE). The seeds of watermelon from Koluedor recorded the highest level of 2.10 µg/kg of p’p-DDE while the lowest level of 0.20 µg/kg of dieldrin and p’p-DDE were recorded in the peel of watermelon from Sege. The mean levels of the detected pesticide residues in peel, pulp and seeds of watermelon were also below maximum residue limits (MRLs)...

This paper reports a multiresidue analytical method based on liquid-liquid extraction and capillary gas chromatography with electron-capture detection (LLE-GC-ECD). The determined analytes belong to two organochlorinated compound classes: polychlorinated bipenyls (PCBs), and organochlorine pesticide (OCPs). This procedure can be used in routine determination of OCPs and PCBs in milk.

IgA nephropathy (IgAN) is the most common form of primary glomerulonephritis. In IgAN, IgA1 molecules with incompletely galactosylated O-linked glycans in the hinge region (HR) are present in mesangial immunodeposits and in circulating immune complexes. It is not known whether the galactose deficiency in IgA1 proteins occurs randomly or preferentially at specific sites. We have previously demonstrated the first direct localization of multiple O-glycosylation sites on a single IgA1 myeloma protein by use of activated ion-electron capture dissociation (AI-ECD) Fourier transform ion cyclotron resonance (FT-ICR) tandem mass spectrometry. Here, we report the analysis of IgA1 O-glycan heterogeneity by use of FT-ICR MS and liquid chromatography FT-ICR MS to obtain unbiased accurate mass profiles of IgA1 HR glycopeptides from three different IgA1 myeloma proteins. Additionally, we report the first AI-ECD fragmentation on an individual IgA1 Oglycopeptide from an IgA1 HR preparation that is reproducible for each IgA1 myeloma protein. These results suggest that future analysis of IgA1 HR from IgAN patients and normal healthy controls should be feasible.

The main source of human exposure to organochlorines is through food, especially food with a high fat content, such as breast milk, which is critical for child hood development. Therefore, it is important to analyze milk and other biological matrices for organochlorine pesticides (OCPs), and then determine the source of the OCP contamination. The objective of this study was to evaluate the degree of contamination by OCP residues and their metabolites in breast milk samples from the municipalities of Mojuí dos Campos and Belterra-Pará, Brazil. The OCPs analyzed were dichlorodiphenyltrichloroethane (DDT) and its metabolites (o,p'-DDT, p,p'-DDT, o,p'-DDE, p,p'-DDE, o,p'-DDD, and p,p'-DDD), aldrin, endrin, dieldrin, hexachlorocyclohexanes (α-HCH, β-HCH, lindane (γ-HCH), and δ-HCH), endosulfan α and β, endosulfan sulfate, heptachlor, and heptachlor epoxide. These substances were analyzed in 22 breast milk samples using gas chromatography with an electron capture detector (GC-ECD). Seven were contaminated with p,p'-DDT and/or p,p'-DDE. The mean p,p'-DDT and p,p'-DDE content in the contaminated samples was 0.0022 and 0.0152 mg•kg -1 of milk, respectively. This contamination may have been due to the inadequate application of DDT until the end of the 1990s for the control of tropical diseases, including malaria. Despite being a preliminary study, the number of contaminated samples was significant, which suggests the need to expand this study to other environmental and biological matrices.

Polychlorinated biphenyls (PCBs) in tropical soil samples from the Central Region of Ghana, and their variation with the soil characteristics were assessed. The soil characteristics of seventy eight samples were first determined. The PCBs was extracted with (1:1) hexane:acetone mixture, and then the extract treated with concentrated H 2 SO 4 , 5% KMnO 4 and copper. The extract was finally eluted from a silica gel column with hexane:dichloromethane (97:3 v/v), and the PCBs analyzed using a gas chromatograph equipped with 63 Ni electron capture detector (GC-ECD model CP 3800). The composition of PCBs homologous in the soils followed the order: hexa-PCBs (31.89%) > penta-PCBs (23.98%) > tri-PCBs (18.47%) > tetra-PCBs (13.67%) > hepta-PCBs (11.99%). The PCB congener profile in the study area was PCB 28 > PCB 153 > PCB 138 > PCB 52 > PCB 101 > PCB 180 > PCB 118. The mean concentration of the PCB congeners (dry matter basis) was PCB 28, 2.27 ± 2.436; PCB 52, 1.84 ± 2.27; PCB 101, 2.17 ± 2.52 µg/kg; PCB 118, 0.83 ± 0.89 µg/kg; PCB 138, 0.99 + 0.91 µg/kg; PCB 153, 1.18 ± 1.11 µg/kg and PCB 180, 1.18 ± 1.19 µg/kg. The mean concentrations of ΣPCBs were 9.15 ± 0.52 µg/kg for the surface soils (0 -10 cm), 7.55 ± 0.56 µg/kg and 7.82 ± 0.55 µg/kg for the 10 -20 cm and 20 -30 cm sub-surface soils respectively. Significant but weak correlations were observed between PCBs and the soil pH, moisture, and exchangeable base. The coefficient of determination for all significant correlations was between 6.6% and 18.75%.

The present study was aimed to detect and quantify major organophosphorus pesticide residues in cauliflower and cucumber collected from different retail markets of Dhaka city, Bangladesh. In this study, a total of 50 vegetable samples (30 samples of cauliflower and 20 samples of cucumber) were analyzed using Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) extraction technique and Gas Chromatography coupled with Flame Thermionic Detector (GC-FTD). Among the 30 analyzed samples of cauliflower, 5 samples (16.7% of the total number of samples) contained residues of chlorpyrifos, quinalphos, acephate and dimethoate, where 4 samples contained multiple pesticide residues. All the contaminated samples of cauliflower contained residues above the EU-MRL. On the other hand, among the 20 analyzed samples of cucumber, only 2 samples (10% of the total number of samples) contained residues of quinalphos and chlorpyrifos at a level being below the EU-MRL. This study reflects the overall s...

A fast, simple, solvent less and inexpensive sample preparation method based on Head space solid-phase micro extraction (HS-SPME) coupled to gas chromatography-electron-capture detector (GC-ECD) is proposed for the determination of mix pesticide residues from vegetable samples. Polydimethylsiloxane (PDMS, 100 μm) fiber was used in this study. The mix pesticides (24 nos.) including organochlorines (15), organophosphates (06) and synthetic pyrethriods (03) were analysed in the vegetable samples (Cabbage, Tomato, Cauliflower, Chilli, Okra, Brinjal, Bottle gourd, Cucumber, Beetroot, Spinach, and Radish) collected from in and around of Lucknow city, India. Present study revealed the presence of HCH, DDT, methylparathion, malathion, chlorpyrifos, monocrotophos, endosulfan, cypermethrin, fenvalerate pesticides. Pesticides residue levels were compared with MRL fixed by Prevention of Food Adulteration Act (PFA), Govt. of India 1954. The method detection limits were in a linearity range of 0....

Electron capture detectors (ECDs) are widely used in gas chromatography to detect electronegative compounds. In this work, we examine the connections between the ECD response and the cross sections for dissociative electron attachment (DEA) determined from low energy electron beam studies in the chloroalkane family, stressing in particular the role of temporary anion state energies. We show that attachment rate coefficients computed from these cross sections are well correlated with ECD response, and that the latter decreases exponentially with increasing energies of the lowest anion states. ECD measurements are also carried out in monochloroalkanes substituted with unsaturated ethenyl and phenyl moieties, and the response is shown to depend strongly on the mixing between the unsaturated π* and the C-Cl σ* temporary anions as exhibited by the vertical attachment energies (VAEs) of these states. The results show good correlations between the chloroalkene and phenyl chloride ECD responses and the VAEs for the mixed states.

The metabolic fate of 2,4-dichlorophenoxyacetic acid (2,4-D)-n-butyl ester in rats has not been extensively studied. Upon subcutaneous administration of a 100 mg/ kg dose of 2,4-D butyl ester to four male Wistar rats, urine samples were analyzed by three analytical techniques for the presence of the butyl ester and metabolites. Thin layer chromatography (TLC), gas chromatography using an electron capture detector (GC-ECD), and gas chromatography-mass spectroscopy (GC-MS) were the techniques employed. 2,4-D butyl ester was rapidly hydrolyzed in the body to form 2,4-D acid. Ninety-five percent of the administered dose was excreted into the urine as the free acid within 48 h of injection, while only a small fraction (5%) was excreted over an additional 48 h. No amino acid conjugates or the parent 2,4-D butyl ester could be detected in the urine of treated rats. A minor metabolite (<2% of dose) was detected by GC-MS analysis of urine samples. This compound appears to be a side chain metabolite of the 2,4-D butyl ester. Some chemical properties of the metabolite were characterized, and a 2,4-D hydroxyethyl ester structure proposed. The mechanism of this minor metabolic formation remains unknown.

Results from polychlorinated biphenyls (PCB) analyses of mussel tissue extracts by immunoassay (PCB RaPID Assay ® ) and conventional gas chromatography-electron-capture detection (GC-ECD) are described and compared. Mussels from natural populations with diverse concentrations of PCBs, mussel tissue fortified with technical Aroclor ® 1254 and a certified reference material are included. A strong correlation is reported between "total" PCBs quantified by both techniques (r 2 = 0.95, n = 27). Immunoassay results, however, exhibited lower values compared to GC-ECD, particularly when GC results are corrected for procedural recovery. A reduced antibody response, due to differences in the congener composition between the mussel extracts and Aroclor ® 1254 (used to raise and calibrate the ELISA), provides the most likely explanation for this difference. Non-parametric statistical analyses confirmed that, although differing from Aroclor ® 1254, PCB congener compositions in the mussel extracts most closely resemble that of Aroclor ® 1254. At very high PCB concentrations (>30 g g -1 dry weight), however, ELISA results are statistically different (P < 0.01) from GC-ECD results, which is likely to be related to the solvation capacity of ELISA diluent. Similarity analysis showed high correlations between the most prominent congeners in Aroclor ® 1254 and immunoassay results. This analysis did not, however, identify a specific chlorine substitution pattern to which the immunoassay preferentially responded. Whilst GC-ECD affords the capability to quantify individual congeners of different reactivity and toxicity, the data reported do indicate that immunoassay offers a rapid and inexpensive alternative method for estimation of "total" PCBs at environmentally significant levels. It is, however, necessary to remove extraneous lipids to reduce matrix effects in the immunoassay.

HCH and DDT, the organochlorine pesticides (OCPs) were measured in soils from northern Uttar Pradesh, India. The average concentration of HCHs and DDTs was 7.58±1.54 ng g-1 and 0.61±0.21 ng g-1 (dry wt.). Compositional analysis of HCH and DDT isomers was carried out to identify the possible contamination sources. The α/γ ratio of HCH (&lt;0.01 - 8.83) reflects the use of technical as well as lindane formulation. The ratio of p,p’-DDT/p,p’-DDE (0.73) and p,p’- DDT/ΣDDT (0.42) indicates the combined effects of past and ongoing usage of DDT. o,p’- DDT/p,p’-DDT (&lt;0.01) ratio suggest the contamination of soils from technical DDT and not from Dicofol type DDT.

In pesticide residue analysis, screening for over 150 compounds has to be performed on a daily basis. As part of the quality control measures it is crucial to verify that the chromatographic system fits the purpose, or if any deterioration occurred during its previous use. The operation conditions of the chromatographic system can be best monitored with properly selected system suitability test (SST) mixtures, which provide information with one injection on the characteristic performance parameters of the whole system from the injector to the detectors. We developed SST mixtures that are also suitable for use with electron-capture, nitrogen-phosphorus and pulse flame photometric detectors. These SST mixtures were applied over 3 years to monitor the system performance parameters, such as the number of effective theoretical plates, resolution, asymmetry, detection limit and selectivity. The applicability and advantages of these tests are illustrated and discussed.

The concentrations of polychlorinated biphenyls (PCBs) were determined in samples of surface seawater collected from five (5) different locations along the coastline of a tropical lagoon. The surface water samples were analysed using gas chromatography coupled with electron capture detector (GC-ECD) with fifteen (15) PCB congeners detected across the studied area. The chlorobiphenyls levels are in the order Ebute Ero > Oko Baba > Ijora > Lagos Island > Unilag lagoon front with levels 107. 89, 53.15, 34.90, 27.78, and 2.15 mg/L, respectively. The enhanced average concentration of PCBs at the Ebute Ero site is due to the predominance of PCB-180 and PCB-185. A negative correlation was found between the total PCB concentration and the level of dissolved oxygen. Although, the results indicated fairly high levels of PCBs, the anthropogenic contributions from industrial releases and domestic activities may be largely associated with the detected concentrations of the di-, tetra-, penta-, hexa-, hepta-, and octa-chlorobiphenyls.

Multi locational persistent data was generated on Nativo 75WG on apple in India. The residues of trifloxystrobin and tebuconazole persisted up to 30 d. The t 1/2 of tebuconzole and trifloxystrobin deposits was between 19.38 and 25.99 d. Trifloxystrobin metabolite CGA 321113 was found maximum (4.9-12.9%) on 20th day. Harvest time residues of Nativo 75WG constituents were BDL in fruits and soil.

Ethiopia is the world's largest producer and exporter of khat. However, pesticides are used intensively to protect khat from destruction of pest and increase its product, which is leading exposure to agricultural workersandkhat chewers. The objective of this paper was to evaluate the levels of Dichloro-Diphenyl-Trichloroethane (DDT) and Benzene Hexachloride (BHC) Metabolite Residues in Blood samples of Khat (Catha edulis) Chewers and Agricultural Workers in Wondogenet district, Sidama National Regional State, Ethiopia using appropriate standard techniques. Data obtained show that in chewers blood samples the concentration was ranked as follows: p,p'-DDE (14.26µgL-1) >p,p'-DDT(5.88µgL-1) > Gamma BHC (3.378µgL-1) >Beta BHC (2.336µgL-1)>Delta BHC (0.506 µgL-1).Whereas ,in sprayer workers the concentration was ranked as follow:p,p'-DDE (13.245µgL-1) >p,p'-DDT(5.468 µgL-1) > Gamma BHC (3.13µgL-1) >Beta BHC (2.169 µgL-1) >Delta BHC (0.469 µgL-1) and in farmers blood sample the concentration of pesticides was as follow;p,p'-DDE (0.193µgL-1) >p,p'-DDT(0.192µgL-1) > Gamma BHC (0.11µgL-1) >Beta BHC (0.07µgL-1) >Delta BHC (0.02µgL-1).There is significant difference in mean concentration of delta BHC,gammaBHC,betaBHC,,ppDDE and ppDDT in blood serum among spray workers and farmers as well as khat chewers and farmers.Furthermore, onepesticides:ppDDE had residues above ADI in blood serum of khat chewers and spray workers.Therefore, vigilant monitoring pesticide levels in khat is imperative for addressing environmental and public health concerns. It is essential for policymakers to take appropriate measures at this critical time to safeguard public health against the threats posed by pesticide pollution in Khat cultivation.

The applicability of PTV splitless and solvent vent injection to the gas chromatographic analysis of 26 pesticides representing different chemical classes was evaluated. All parameters related to optimum injector performance in PTV splitless and PTV solvent vent (split vent) injection modes were tested. For PTV splitless injection of small sample volumes (1 lL), the inlet temperature program (initial inlet temperature, heating rate, final temperature), splitless time, and starting oven temperature were optimized. Parameters identified as optimal were then applied in PTV solvent vent injection. In the case of the PTV solvent vent technique, all injections were performed with pesticides dissolved in a binary mixture of cyclohexane-ethyl acetate (1 : 1, v/v). This solvent is used as a mobile phase in the HPGPC clean-up step involved in our multiresidue method. For the PTV solvent vent technique the following parameters were tested: maximum single injection volume, inlet temperature, vent flow, vent time, and vent period were determined for a single injection of 10 lL of sample. Thermodegradation and/or adsorption of some pesticides occurred as long as glass wool packed liner was used. To achieve lower detection limits, multiple injection concept was employed: 30 lL of standard solution were injected in three subsequent steps. Under optimized conditions even higher sample volumes could be injected. Good responses were obtained also for the compounds possessing relatively higher volatility compared to other tested analytes.