Thermionic Detector Research Articles

Method Development and Validation of Gas Chromatography Methods using Nitrogen Phosphorus Detector (GC-NPD) and Isotope Dilution Triple Quadrupole Mass Spectrometry (GC-IDMS/MS) for the Determination of Chlorpyrifos in Mango

Pesticides residue determination in fruits like chlorpyrifos is important due to its health effects on humans. Thus, there is a need for sensitive and accurate methods for better quantification. In this study, the performance of two gas chromatographic detection methods, nitrogen phosphorus detector (GC-NPD) and isotope dilution triple quadrupole mass spectrometer (GC-IDMS/MS), for the determination of chlorpyrifos in mango was evaluated to be used for the development of candidate reference material. Other than liquid-liquid extraction (LLE), Quick, Easy, Cheap, Efficient, Rugged and Safe (QuEChERS) sample extraction and dispersive solid phase extraction (dSPE) clean-up procedures were optimized to extract chlorpyrifos from the sample matrix. Comprehensive method validations were performed in GC-NPD and GC-IDMS/MS with HP-5 capillary column to establish linearity, the limit of detection (LOD), the limit of quantification (LOQ), accuracy, repeatability, and intermediate precision using freeze-dried mango samples. The LOD and LOQ were 2.35 and 3.47 µg kg-1 for GC-NPD, and 1.23 and 1.85 µg kg-1 for GC-IDMS/MS, respectively. Matrix-matched calibration curves showed excellent linearity of r2=0.999 for both GC-NPD and GC-IDMS/MS protocols. Acceptable repeatability was obtained for three spike concentrations of 10, 30, and 60 µg kg-1 (n=10) and intermediate precision for 0.5-, 1- and 3-months in the same three-spike concentrations (n=3) expressed as relative standard deviation (RSD) ranging from 0.34-5.61 % for GC-NPD and 0.46-4.22 % for GC-IDMS/MS. Satisfactory mean recoveries (n=10) were achieved: 88.48-109.81% in GC-NPD and 97.61-108.40% in GC-IDMS/MS. GC-IDMS/MS and GC-NPD methods were fit for the purpose of quantifying chlorpyrifos in Philippine mango accurately with the use of isotope dilution technique and traceability to international standards by the application of gravimetric sample preparation.

Simple and simultaneous quantification of cyanide, ethanol, and 1-propanol in blood by headspace GC–MS/NPD with Deans switch dual detector system

Cyanide is a powerful and rapidly acting poison. In Japan, cyanide poisoning is rare, and regular cyanide testing can be costly and time consuming. In contrast, alcohol analysis is routinely performed in most forensic laboratories. In this study, we attempted to develop a method for the simultaneous quantification of cyanide and alcohols in blood using headspace gas chromatography (HS–GC). As nitrogen-phosphorus detection (NPD) is more sensitive to hydrogen cyanide than mass spectrometry (MS), a Deans switch was used to switch the detectors during a single run. The separation provided by three analytical columns, PoraBOND Q, CP-Sil 5 CB, and HP-INNOWax, was investigated, and PoraBOND Q was selected. The use of HS–GC–MS/NPD with a Deans switch enabled the simple and simultaneous quantification of cyanide, ethanol, and 1-propanol. Eighteen other volatile compounds were detected in the SIM/scan mode of the MS.

A Full Evaporation Static Headspace Gas Chromatography Method with Nitrogen Phosphorous Detection for Ultrasensitive Analysis of Semi-volatile Nitrosamines in Pharmaceutical Products

The recent detection of potent carcinogenic nitrosamine impurities in several human medicines has triggered product recalls and interrupted the supply of critical medications for hundreds of millions of patients, illuminating the need for increased testing of nitrosamines in pharmaceutical products. However, the development of analytical methods for nitrosamine detection is challenging due to high sensitivity requirements, complex matrices, and the large number and variety of samples requiring testing. Herein, we report an analytical method for the analysis of a common nitrosamine, N-nitrosodimethylamine (NDMA), in pharmaceutical products using full evaporation static headspace gas chromatography with nitrogen phosphorous detection (FE-SHSGC-NPD). This method is sensitive, specific, accurate, and precise and has the potential to serve as a universal method for testing all semi-volatile nitrosamines across different drug products. Through elimination of the detrimental headspace-liquid partition, a quantitation limit of 0.25 ppb is achieved for NDMA, a significant improvement upon traditional LC-MS methods. The extraction of nitrosamines directly from solid sample not only simplifies the sample preparation procedure but also enables the method to be used for different products as is or with minor modifications, as demonstrated by the analysis of NDMA in 10+ pharmaceutical products. The in situ nitrosation that is commonly observed in GC methods for nitrosamine analysis was completely inhibited by the addition of a small volume solvent containing pyrogallol, phosphoric acid, and isopropanol. Employing simple procedures and low-cost instrumentation, this method can be implemented in any analytical laboratory for routine nitrosamine analysis, ensuring patient safety and uninterrupted supply of critical medications.Graphical

Farmer’s Awareness on Pesticide Waste Management and Role of Pesticides in Water Contamination in Bahawalpur, Punjab, Pakistan

This study emphasizes the awareness and training of farmers on sustainable agricultural practices for restrictive use of pesticides to reduce water pollution caused by pesticides in rural areas. For this assessment, 150 feasible farmers were selected randomly using a convenient sampling technique. Data was collected through interviews (n=30) and questionnaires (n=120). Data was scrutinized in SPSS software. To examine freshwater contamination with pesticides, freshwater samples were collected from open water bodies (5 wells) in the area of tehsil Hasilpur (29.6902° N, 72.5796° E) and Qaimpur of Bahawalpur, Punjab, and analyzed for eight pesticides which are frequently used. ECD: Electron Capture Detector was used to detect the organochlorine pesticides, herbicides, and various halogenated hydrocarbons. NPD: Nitrogen Phosphorus Detector was used to detect nitrogen- or phosphorus[1]containing compounds. Approximately 80% of farmers revealed that they never got any training or informative 64 sessions for pest management other than using chemical pesticides. The remaining 20% were trained by some private non-toxic pesticide manufacturing firms operating in Pakistan. Although non-significant cooperation from the government bodies of the state, the correlation among respondents’ profiles and the extent of training they have received in total was positive. Results for pesticide contamination were astonishing as 6 out of 8 pesticides were detected in water samples with alarming concentrations of Carbofuran (23.1µg/l) and Monocrotophos (8.3µg/l) which can be fatal for animals and humans in prolonged usage. The use of pesticides in a preventive and sustainable way gives more protection against pests and minimizes pollution such as water pollution or air pollution, etc., caused by the chemicals (pesticides). Hence such sustainable practices must be adopted for better production and conservation of the environment.

Monitoring of pesticide residues in vegetables collected from retail markets of Dhaka district of Bangladesh using QuEChERS Extraction and Gas Chromatography

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 scenario of pesticide residues remain in cauliflower and cucumber purchased from different local markets of Dhaka city, which will help the consumer to be aware of their health and safety. The findings derived from this study reveals the public health concern due to the potential of pesticide toxicity in vegetables for the consumers. Therefore, continuous monitoring on the use of pesticides in vegetables should be strengthened. Asian Australas. J. Food Saf. Secur. 2021, 5 (2), 63-70

Determination of five 3-alkyl-2-methoxypyrazines employing HS-SPME-GC-NPD: Application in evaluation of off-flavor of South American wines

High concentrations of 3-alkyl-2-methoxypyrazines (MPs) in wines can affect the quality and contribute to the rejection of consumers. This work proposes the determination of five MPs in nine wine samples from South America using headspace solid phase microextraction with gas chromatography coupled to nitrogen-phosphorus detector. The separation of the analytes was performed with a HP 5 capillary column in temperature gradient mode and injection in splitless mode. The optimization of the main parameters gives the optimal extraction conditions: Divinylbenzene-Carboxen-Polydimethylsiloxane fiber, sample dilution ratio of 1:3 with water, salt addition of 30 % (w/v) sodium chloride, extraction time of 30 min and extraction temperature of 35 °C. The main parameters of merit of the method were evaluated, showing coefficients of determination greater than 0.995, limits of detection ranging from 6.10–31.2 ng L−1, recovery from 75.2–118% and precisions with values less than 20 %. The validation parameters obtained and the concentration levels of ng L−1 achieved characterize this method as efficient for the determination of these off-flavors in wine. From the nine analysed wines, 3-ethyl-2-methoxypyrazine and 3-isobutyl-2-methoxypyrazine were identified and quantified. The levels are well above the odor detection threshold, thus contributing to generation of off-flavor in the aroma and flavor of these wines.

Estimation of residue degradation of cypermethrin and chlorpyrifos in brinjal, tomato and cauliflower under supervised field trial

A study was carried out to detect and estimate the residue of cypermethrin and chlorpyrifos in brinjal, tomato and cauliflower using Gas Chromatography (GC) coupled with Electron Capture Detector (ECD) and Flame Thermionic Detector (FTD). Three supervised field trials were conducted and sprayed with the recommended dose of cypermethrin (1 ml/L of water) and chlorpyrifos (3 ml/L of water) in three vegetables by knapsack sprayer. Samples were collected at 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, and 11 days after spray (DAS). The quantity of cypermethrin residue was above EU-MRLs (Maximum Residue Limit set by European Union) up to 4 DAS with 0.538 mg/kg in cauliflower; 3 DAS with 0.508 mg/kg in brinjal and 0.695 mg/kg in tomato. The quantity decreased down 0.328-0.019 mg/kg in cauliflower (4-9 DAS); 0.098-0.012 mg/kg (4-7 DAS) in brinjal and 0.458-0.022 mg/kg (4-7 DAS) in tomato which were below EU-MRLs (0.5 mg/kg). The quantity of chlorpyrifos residue was above EU-MRLs up to 9 DAS with 0.012 mg/kg in cauliflower but in brinjal and tomato, the detected quantities were above EU-MRLs up to 7 DAS with 0.029 mg/kg and 0.017 mg/kg residue. No residue was detected from brinjal and tomato samples collected at 8 DAS. But in cauliflower, no residue was detected at 10 days after spray. So, brinjal, tomato and cauliflower can be harvested safely at 4 DAS and 5 DAS for cypermethrin and in case of chlorpyrifos it was 8 DAS in brinjal and tomato and 10 DAS in cauliflower. Asian Australas. J. Biosci. Biotechnol. 2021, 6 (2), 60-67

Human health risk assessment through quantitative screening of insecticide residues in two green beans to ensure food safety

Food contamination with pesticide residues is a serious concern, particularly in developing countries. The study analyzed samples of country bean (Lablab purpureus L.) and yard long bean (Vigna unguiculata L.) for residues of widely used insecticides to ensure food safety. We used a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction method followed by gas chromatography (GC)-flame thermionic detector (FTD) for quantitative estimation of pesticide residues. Mostly, the residues of chlorpyrifos, dimethoate and quinalphos were found in 11 and 14 % of country bean and yard long bean samples, respectively. About 50 % of the insecticide-contaminated bean samples contained residues above the maximum residue limit (MRL), which warrants a caution about the extensive and intensive use of pesticides in modern agriculture. The general claim of pesticide adulteration could contribute to the widespread occurrence of several insecticides in beans that threatens food safety. The assessment for chronic non-cancer health risk, based on estimated daily intake (EDI) and hazard quotient (HQ), suggests that the consumption of insecticide-contaminated beans poses potential threat to the health of adults (EDI: 2.79 × 10−4–2.96 × 10−4 and HQ: 0.56‒0.59) as well as children (EDI: 9.79 × 10−4–1.77 × 10‒3 and HQ: 1.96–3.55). Overall, our results clearly indicate that around 50 % of insecticide-contaminated bean samples, available at various local markets in Bogura district of Bangladesh, may cause health risks in humans. The present observations might help the regulatory authorities concerned in setting new guidelines for the limits of pesticide residues in commonly used bean vegetables, and in monitoring the quality of commercial formulations.

Pre-workout supplements marketed in Brazil: Caffeine quantification and caffeine daily intake assessment.

The stimulating and performance-enhancing properties of caffeine are often explored in one the most consumed types of supplements: the pre-workout supplements (PWS). However, despite the popularity of PWS, previous studies have reported incompatibilities between what is described in their labels and their actual caffeine content. This study aimed to develop, to optimize, and to validate a gas-chromatography coupled to nitrogen-phosphorus detector (GC-NPD) method to quantify caffeine in PWS and to analyze commercial PWS marketed in Brazil to estimate the caffeine daily intake. For this purpose, three different extraction procedures were evaluated: agitation in vortex, shaker, and sonication. Sonication yielded the best extraction results. Next, the parameters' temperature and time were optimized by using central composite rotatable design (CCRD) and response surface methodology, which revealed the optimal values of 70°C and 10min. The method was validated and applied to quantify caffeine in 52 PWS. From the 36 PWS labels that specified the caffeine amount, seven (19%) presented more than 120% of the declared quantity, whereas 15 (42%) contained less than 80% of the labeled caffeine. Additionally, six products presented undeclared caffeine. Considering the label stated doses, five supplements exceeded the safe caffeine daily intake (400 mg). On the basis of these findings, supplement quality control remains an issue that deserves more attention from consumers, manufacturers, and regulatory agencies. Finally, we suggest that PWS consumers be careful of the habit of ingesting caffeine through other sources and avoid ingesting two or more different PWS products in the same day.

Nitrogen-containing aromatic compounds: quantitative analysis using gas chromatography with nitrogen phosphorus detector

The nitrogen-containing aromatic compounds found in the petrochemical industry are varied and extend beyond classes such as the anilines, pyrroles and pyridines. Quantification of these nitrogen-containing compounds that may occur in complex mixtures has practical application for quality assurance, process development and the evaluation of conversion processes. Selective detection of nitrogen-containing species in complex mixtures is possible by making use of gas chromatography coupled with a nitrogen phosphorous detector (GC-NPD), which is also called a thermionic detector. Despite the linearity of the NPD response to individual nitrogen-containing compounds, the response factor is different for different compounds and even isomers of the same species. Quantitative analysis using an NPD requires species-specific calibration. The reason for the sensitivity of the NPD to structure is related to the ease of forming the cyano-radical that is ionized to the cyanide anion, which is detected. The operation of the NPD was related to the processes of pyrolysis and subsequent ionization. It was possible to offer plausible explanations for differences in response factors for isomers based on pyrolysis chemistry. Due to this relationship, the NPD response can in the same way be used to provide information of practical relevance beyond its analytical value and a few possible applications were outlined.

Dissipation, residue, dietary, and ecological risk assessment of atrazine in apples, grapes, tea, and their soil.

Atrazine is one of the most used herbicides in China. It is a persistent organic pollutant but has been widely used on Chinese farmlands for a long time. To assess its dietary and ecological risks to human and environment, in this study, atrazine residues were extracted with acetonitrile and then plant samples were detected with gas chromatography coupled with mass spectrometry (GC-MS) and soil samples were determined with gas chromatography coupled with nitrogen-phosphorus detector (GC-NPD). The limit of quantification (LOQ) of the method was 0.01 mg/kg for all matrices. The recoveries ranged from 82.0 to 105.4% for plant samples and 75.6 to 85.6% for soil samples. The final residues of atrazine in all plant samples were lower than LOQ. Dietary risk assessment suggested that under good agricultural practices (GAP) conditions, intake of atrazine from apples, grapes, and tea would exhibit an acceptably low health risk on consumers. However, the final residues of atrazine in soil samples were <0.01-9.2 mg/kg, and the half-lives were 2.0-9.1 days. Based on the species sensitivity distribution (SSD) model, the potential affected fraction (PAF) of atrazine in soil samples ranges from 0.01 to 65.8%. Atrazine residues in 43.1% soil samples were higher than 0.11 mg/kg, which was the hazardous concentration for 5% of species (HC5) of atrazine in soil. These results suggested that the ecological risks of atrazine in apples, grapes, and tea garden soil would exhibit a high risk on environmental species even under the same GAP conditions. This study could provide guidance for comprehensive risk assessment of atrazine properly used in apple, grape, and tea gardens.

Determination of organophosphorus and synthetic pyrethroid pesticide residues and their variability in large size fruit crops

Variability of pesticide residues in food item plays a key role for the evaluation of consumer food safety. However, variability factors (VFs) derived from the large size fruit crops are still scarce. Therefore, the present work was aimed to quantify pesticide residues and to estimate VFs in large size fruit crops of mango and guava. A total of 140 mango and 130 guava samples from different marketplaces in Bangladesh were collected to estimate the variability of pesticide residues (acephate, diazinon, malathion, fenitrothion, chlorpyrifos, quinalphos, dimethoate and cypermethrin) by in-house validated methods based on modified QuEChERS extraction and gas chromatography coupled with electron capture detector (ECD) and flame thermionic detector (FTD). The method was validated at three fortification levels (0.01, 0.10 and 0.30 mg kg-1 ) and satisfactory recoveries (80-111%) with relative standard deviation (RSDr ) ≤ 13% were achieved. A wide variation of residues was found in the analyzed samples. In the case of mango, the ranges of residues were 0.011-0.314, 0.015-0.04, and 0.05-0.291 mg kg-1 , respectively, for cypermethrin, chlorpyrifos, and dimethoate, while in the case of guava, the ranges were 0.04-0.113, and 0.03-0.290 mg kg-1 , respectively, for cypermethrin and acephate. The average VF for mango was 4.06 and it was 5.70 for guava. VFs originating from the marketed samples of mango and guava are reported in this study for the first time. The estimated VFs were higher than the default value of 3, therefore, the default VFs should be reconsidered when more data are obtained regarding large size crops. © 2021 Society of Chemical Industry.

Pesticide Residue Analysis from Winter Vegetables Collected from Six Markets of Rajshahi Bangladesh

Pesticide residues in vegetables have become a major concern associated with food safety issues. Five types of winter vegetables like bean, brinjal, tomato, cauliflower and cabbage were collected from six markets of Rajshahi District during January, , 2019 in Bangladesh. Residues of commonly used pesticides (Acephate, Dimethoate, Diazinon, Fenotrothion, Malathion, Chlorpyrifos and Quinalphos) in winter vegetable samples were determined using Gas Chromatography-Flame Thermionic Detector (GC-FTD) procedures. A quick, easy, cheap, effective, rugged and safe (QuEChERS) method with acetate buffering (AOAC Official Method 2007.01) was used for sample preparation. Out of 30 samples, pesticide residues were found only in one brinjal and two tomato samples. The result showed that tomato samples collected from Shaheb bazar and Kharkhari bazar of Rajshahi City contained 0.047 mg/kg and 0.139 mg/kg dimethoate residue, respectively. Brinjal sample collected from Shalbagan bazar, Rajshahi, contained 0.052 mg/kg dimethoate residues. The detected pesticide residue dimethoate of these three samples was higher than maximum residue level (0.01 mg/kg).&#x0D; Environ. Sci. &amp; Natural Resources, 12(1&amp;2): 43-50, 2019

Optimization of a QuEChERS Based Analytical method for the Determination of Organophosphorus and Synthetic Pyrethroid Pesticide Residues in Betel Leaf

ABSTRACT A novel method has been developed and validated for the first time in order to determine eight pesticide residues (acephate, diazinon, malathion, fenitrothion, chlorpyrifos, quinalphos, dimethoate and cypermethrin) in betel leaf using quick, easy, cheap, effective, rugged and safe (QuEChERS) extraction in combination to Gas Chromatography (GC) coupled with Flame Thermionic Detector (FTD) and Electron Capture Detector (ECD). In this study, the optimisation of cleanup materials was done properly and found that 600 mg anhydrous MgSO4, 150 mg activated charcoal powder, and 120 mg PSA (Primary Secondary Amine) was the best combination for proper cleanup of betel leaf matrix. Recoveries for all the selected pesticides at fortification levels of 0.02, 0.1, and 0.3 mg/kg ranged from 86% to 108% with RSDr ≤ 9% and the matrix matched calibration curve showed good linearity (r2 ≥ 0.996). The limit of detection ranged from 0.003 to 0.005 mg/kg and the limit of quantification was 0.02 mg/kg, which was lower than the EU-MRLs. The matrix effects of the selected pesticides were also evaluated in this study and found that cypermethrin had a prominent matrix effect (+124%). The proposed method was applied successfully to analyse 110 fresh betel leaf samples and found that 12 were contaminated with cypermethrin, chlorpyrifos, and dimethoate at a level above EU-MRLs. The consumers are at high health risk as the detected levels of cypermethrin and chlorpyrifos residues were up to 78 and 39 times higher than the EU-MRLs, respectively, and the estimated highest Health Risk Index (HRI) was 5.40.

Lowland tapir exposure to pesticides and metals in the Brazilian Cerrado

Abstract Context The Cerrado is a Global Biodiversity Hotspot as well as Brazil’s main frontier for large-scale agriculture and livestock production, making it one of the most threatened biomes in the country. Brazil is one of the biggest consumers of pesticides in the world and allows the use of chemicals that are banned in many other countries due to their adverse health effects in a wide range of species, including humans. Aims This study aimed to assess pesticide and metal exposure of the lowland tapir – a threatened, large herbivorous mammal – to support future studies of the role of these chemicals in tapir health, survivorship, and population viability. Methods Foot pad, proboscis, stomach contents, liver, bone, and nail samples were obtained from tapir carcasses found along highways (n = 87). (i) Atomic absorption spectrophotometry (AAS) was used to detect metals in bone, nail and liver tissue; (ii) gas chromatography – nitrogen phosphorous detector (GC-NPD) to detect organophosphates in liver and skin; and (iii) high performance liquid chromatography – ultraviolet (HPLC-UV) to detect pyrethroids and carbamates in stomach contents. Key results Two carbamates (aldicarb and carbaryl), three organophosphates (diazinon, malathion, and mevinphos), two pyrethroids (deltamethrin and permethrin), and two toxic metals (cadmium and lead) were detected in different tapir tissue samples, some at concentrations high enough to cause adverse health effects. In 90% of roadkill tapirs that were subjected to a full post-mortem examination (n = 25), macroscopic alterations of liver and/or kidney tissue were observed. Conclusions This study provides the first report to date of the detection of pesticides and metals in lowland tapirs. Implications Some of the reported pesticide concentrations exceed environmental safety thresholds. Consequently, results from this study raise concerns over potential adverse health effects in tapirs that could lead to population level impacts, thus requiring further investigation.

Validation of Quechers Analytical Method for Analysis of Organophosphorus Residues in Okra

An analytical method of gas chromatography (GC) with flame thermionic detector (FTD) was developed and validated for the simultaneous determination of 14 organophosphorus pesticides in okra. The residues were extracted using modified QuEChERS method and validated in terms of linearity, sensitivity, precision and accuracy. The limit of quantification (LOQ) of the proposed method was 0.01 µg/ g. The developed procedure gave satisfactory recoveries for organophosphates to an extent of 85.91-114.44, 81.74-105.90 and 80.10-107.64% at 0.01, 0.05 and 0.1 µg/ g, respectively with associated RSDs of ≤ 20% for all compounds. The proposed method is highly efficient, quick, robust and consequently the method is suitable for monitoring pesticide residue in okra samples.

Determination of 2-acetyl-1-pyrroline in alginate encapsulated pandanus flavorings by static headspace (SHS) and gas chromatography with nitrogen–phosphorus detection (GC-NPD)

A new form of Pandanus flavoring has been developed using the ionic gelation method. Among the four Pandanus species investigated by solid-phase microextraction (SPME)–gas chromatography–mass spectrometry (GC–MS), the leaves of P. amaryllifolius Roxb. contained the highest content of the impact aroma compound, 2-acetyl-1-pyrroline. Some terpene volatiles were identified for the first time in these Pandanus species. Acidic extraction with aqueous tartaric acid at pH 5 was the most suitable solvent for obtaining 2-acetyl-1-pyrroline from Pandanus leaves. Moreover, the extract was directly subjected to ionic gelation with the optimized sodium alginate and calcium chloride concentrations of 1.5 and 3% w/v, respectively. Automated static headspace–gas chromatography with a selective nitrogen–phosphorus detection was developed and validated to determine 2-acetyl-1-pyrroline in the dried green alginate beads. The response surface optimization of headspace sample parameters resulted in an optimal equilibration time of 20 min and oven temperature at 123 °C. The 2-acetyl-1-pyrroline standard calibration curve was linear from 1.0 to 640 μg g−1 with a correlation coefficient of 0.9998. The limits of detection and quantification were 0.10 and 0.80 μg g−1, respectively. On average, a 2-acetyl-1-pyrroline content of 18.49 μg g−1 (16.89 to 26.91 μg g−1) was encapsulated in the green dried alginate flavoring products, which was two to three times higher than contained in fresh Pandanus leaves. After 90 days of storage, the 2-acetyl-1-pyrroline content remaining in the green dried alginate beads was 79% of the initial content.

A Comparison of the Limits of Detection for a Number of Surrogates of Organophosphorus Toxic Agents and Methylphosphonic Acid Silyl Derivatives and its O-Alkyl Esters by Gas Chromatography/Mass Spectrometry with Various Ionization Methods and a Flameless Thermionic Ionization Detector

Electron ionization (EI) and chemical ionization (CI) mass spectra of methylphosphonic acid phosphates and phosphonates (surrogates of respective chemical war agents) and silyl derivatives and its O-alkyl esters (markers of hydrolysis products of chemical war agents) were investigated and respective limits of detection were determined by GC/MS (EI) and GC/MS (CI) in a single ion monitoring mode. Atmospheric pressure photo- and photochemical ionization (APPI/APPCI) mass spectra of the same compounds were investigated by GC/MS (APPI/APPCI) and conditions providing the registration of mass spectra consisting of only one peak, corresponding to the M+ or [M + H]+ ion, were chosen and the limits of detection in the single ion monitoring mode were determined. In addition, the limits of detection for all of the studied compounds by GC with a flameless thermionic detector (FTID) were determined. The limits of detection for phosphates and phosphonates by GC/MS (EI) (MS/MS), GC/MS (CI), GC/MS (APPI), and GC/MS (APPCI) and in the single ion monitoring mode were 0.2–1.0 pg, 1.0–6.0 pg, 10–30 pg, and 0.1–0.3 pg, respectively. For methylphosphonic acid silyl derivatives and its O-alkyl esters, the respective limits of detection were 0.2–4.0 pg, 1.0–5.0 pg, 10–25 pg, and 1.0–3.0 pg. The limits of detection for all the studied compounds by GC with FTID were 0.3–0.4 pg. This means that the rapid screening of the samples to be investigated should be based on the last named method and GC/MS must be used only for the selected samples.

Health risk assessment of pesticide residues in vegetables collected from northern part of Bangladesh

The use of synthetic pesticides for agricultural production in developing countries like Bangladesh is unavoidable. Therefore, there is also a concern for the residual effects in public health. The present study aimed to assess the health hazards associated with the residual effect of pesticides in two common vegetables (cauliflower and tomato) collected from five different markets of a northern city of Bangladesh. A total 80 samples (i.e. 40 of each vegetable) were collected for the analysis of seven major organophosphorus insecticides namely acephate, chlorpyrifos, diazinon, dimethoate, fenitrothion, malathion and quinalphos used in that region. Modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) extraction technique and GC-FTD (Gas Chromatography coupled with Flame Thermionic Detector) used for the analysis of the samples. Results indicate that 11 (6 cauliflower, 5 tomato) analyzed samples contained residues which are about 14% of the total number of samples. Most of the samples contaminated diazinon at a level above EU-MRLs. However, health risk assessment based on ADI, the contaminated samples were safe. Continuous monitoring together with a sample traceability system is suggested to protect consumers’ health from the cumulative effects of other contaminated dietary products.

Pattern of Suicide Methods and Postmortem Toxicological Findings in Suicide-Related Deaths: A Retrospective 7-Year Forensic-Based Study in Iran.

Suicide is a public health threat that leads to morbidity and mortality worldwide. In this study, we evaluated postmortem toxicological finding among forensic autopsies on suicidal deaths from 2010 to 2016 at the Legal Medicine Center of Zanjan Province (northwest of Iran). All suicide fatal cases were investigated to define the cause and manner of death. Toxicological analyses were performed using thin-layer chromatography, high-performance liquid chromatography, gas chromatography/mass spectrometry, headspace gas chromatography, and gas chromatography equipped with nitrogen phosphorus detector. Demographic data (age, sex, educational level, residential location, and marital status), cause of death, and postmortem toxicological findings were extracted from forensic reports and were entered into the designed questioners. During this period, a total of 181 cases of suicide deaths were investigated. Among them, 74% were male. The most often used suicide method was hanging, followed by self-poisoning in young people. Aluminum phosphide was the most frequent poison detected in the fatal suicidal cases (33 cases), followed by opioids. Hanging and self-poisoning were the frequent suicidal method in young male population. It seems that psychological and social supports in young people along with restriction to easy access to drugs and poisons should be considered by policy making and healthcare authorities.