Monitoring and method validation of organophosphorus/organochlorine pesticide residues in vegetables and fruits by gas chromatography.

In this study, an analytical method was developed and validated for the assessment of pesticide residues in commonly consumed vegetables and fruits. Fresh samples of apple, green peas, tomatoes, and cucumbers were processed and subjected to analysis using a modified QuEChERS (quick, easy, cheap, effective, rugged, safe) extraction technique. Subsequently, quantification of pesticide residues was conducted utilizing gas chromatography (GC)-electron capture detector. Extraction and cleanup parameters were meticulously optimized, resulting in a modification of the original QuEChERS method. This modification aimed to reduce solvent consumption, making the study more environmentally friendly. The developed method was validated in terms of selectivity, specificity, linearity, precision, and accuracy by following the SANTE guidelines. Calibration curves showed good linearity (r > 0.99) within the test range. Precision was evaluated by intra- and inter-day experiments with an acceptable relative standard deviation (<20.0%). Recovery was assessed at the limit of quantification level and was observed to fall within the range of 70%-120%, with relative standard deviations below 5.45%. The validated method presented here can be applied to analyze pesticide residues in various other vegetables, fruits, and cereals. It is essential for ongoing monitoring of pesticide residues to ensure public safety.

Spectroscopic characterization and pharmacokinetic evaluation of amorphous solid dispersions of glibenclamide for bioavailability enhancement in Wistar rats.

Oral bioavailability of glibenclamide (Glb) was appreciably improved by the formation of an amorphous solid dispersion with Poloxamer-188 (P-188). Poloxamer-188 substantially enhanced the solubility and thereby the dissolution rate of the biopharmaceutics classification system (BCS) class II drug Glb and simultaneously exhibited a better stabilizing effect of the amorphous solid dispersion prepared by the solvent evaporation method. The physical state of the dispersed Glb in the polymeric matrix was characterized by differential scanning calorimetry, X-ray diffraction, scanning electron microscope and Fourier transform infrared studies. In vitro drug release in buffer (pH 7.2) revealed that the amorphous solid dispersion at a Glb-P-188 ratio of 1:6 (SDE4) improved the dissolution of Glb by 90% within 3 h. A pharmacokinetic study of the solid dispersion formulation SDE4 in Wistar rats showed that the oral bioavailability of the drug was greatly increased as compared with the market tablet formulation, Daonil®. The formulation SDE4 resulted in an AUC0-24h ~2-fold higher. The SDE4 formulation was found to be stable during the study period of 6 months.

The Pregnancy, Arsenic, and Immune Response (PAIR) Study in rural northern Bangladesh.

BACKGROUND: Arsenic exposure and micronutrient deficiencies may alter immune reactivity to influenza vaccination in pregnant women, transplacental transfer of maternal antibodies to the foetus, and maternal and infant acute morbidity. OBJECTIVES: The Pregnancy, Arsenic, and Immune Response (PAIR) Study was designed to assess whether arsenic exposure and micronutrient deficiencies alter maternal and newborn immunity and acute morbidity following maternal seasonal influenza vaccination during pregnancy. POPULATION: The PAIR Study recruited pregnant women across a large rural study area in Gaibandha District, northern Bangladesh, 2018-2019. DESIGN: Prospective, longitudinal pregnancy and birth cohort. METHODS: We conducted home visits to enrol pregnant women in the late first or early second trimester (11-17 weeks of gestational age). Women received a quadrivalent seasonal inactivated influenza vaccine at enrolment. Follow-up included up to 13 visits between enrolment and 3 months postpartum. Arsenic was measured in drinking water and maternal urine. Micronutrient deficiencies were assessed using plasma biomarkers. Vaccine-specific antibody titres were measured in maternal and infant serum. Weekly telephone surveillance ascertained acute morbidity symptoms in women and infants. PRELIMINARY RESULTS: We enrolled 784 pregnant women between October 2018 and March 2019. Of 784 women who enrolled, 736 (93.9%) delivered live births and 551 (70.3%) completed follow-up visits to 3 months postpartum. Arsenic was detected (≥0.02 µg/L) in 99.7% of water specimens collected from participants at enrolment. The medians (interquartile ranges) of water and urinary arsenic at enrolment were 5.1 (0.5, 25.1) µg/L and 33.1 (19.6, 56.5) µg/L, respectively. Water and urinary arsenic were strongly correlated (Spearman's ⍴ = 0.72) among women with water arsenic ≥ median but weakly correlated (⍴ = 0.17) among women with water arsenic < median. CONCLUSIONS: The PAIR Study is well positioned to examine the effects of low-moderate arsenic exposure and micronutrient deficiencies on immune outcomes in women and infants. REGISTRATION: NCT03930017.

Method validation and residue determination of mineral oil Arbofine in apple and soil using gas chromatography-flame ionisation detection under temperate conditions of Kashmir, India.

This innovative study was carried out to determine the presence of the mineral oil Arbofine in apple and soil at four locations. Arbofine kills the vast majority of dormant insects and mites (mite and asphid eggs, scales and psyllids) on fruit trees (cherry, apple, plum and peach) and thus reduces the plant diseases in summer. In this study, the mineral oil was sprayed at recommended doses of 2.0 and 0.75%, and the doses were doubled to 4.0 and 1.5% in dormant and summer seasons, respectively. The soil samples were taken for observation during the dormant season, whereas both soil and apple samples were taken during the summer season after treatment for 0, 1, 3 and 5 days. The recovery study of all the 11 paraffinic constituents (n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane and n-pentadecane) in soil and apple samples which constitutes 60% of mineral oil in soil and apple was carried out at the fortification level of 1.0 µg/ml, which was found to be between 72.1% and 99.0%. No residue of all the 11 paraffinic compounds of Arbofine mineral oil was detected in soil and apple samples at day 0 after the recommended doses, and the recommended doses were doubled in both seasons at four locations. Therefore, mineral oil can be used on apples without any risk.

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

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

Development and validation of gas chromatography with electron capture detection method using QuEChERS for pesticide residue determination in cucumber.

A modified quick, easy, cheap, efficient, rugged, and safe (QuEChERS) method coupled to gas chromatography with electron capture detection was developed for the simultaneous determination of selected electronegative pesticides, namely, chlorpyrifos-methyl (1), chlorpyrifos (2), quinolphos (3), profenofos (4), myclobutanil (5), ethion (6), fenpropathrin (7), and cypermethrin (8), in vegetables with high water content. The selected compounds and some of their metabolites have even been found in human body fluids. In addition, some of them are known or suspected carcinogens according to the World Health Organization. Extraction and cleanup parameters were optimized; thus, the original QuEChERS method was modified to minimize solvent usage by making the study eco-friendly. The developed method was validated for selectivity, specificity, linearity, precision, and accuracy using SANTE guidelines. Calibration curves showed good linearity (r > 0.99) within the test range. Precision was evaluated by intra- and inter-day experiments with an acceptable range of less than 20.0% of relative standard deviation. Recovery was evaluated at limit of quantification and was found to be in the range of 70-120%, with relative standard deviations lower than 4.21%. The proposed method is applicable for detection and monitoring of selected pesticides in one run not only in fruits and vegetables with high water content but also in samples containing large quantities of pigments/dyes.

Simultaneous quantification of losartan potassium and its active metabolite, EXP3174, in rabbit plasma by validated HPLC-PDA.

Herein, we report a novel, accurate and cost-effective validated analytical method for the quantification of losartan potassium and its active metabolite, EXP 3174, in rabbit plasma by reversed-phase high-performance liquid chromatography. Valsartan was used as an internal standard. The method was validated as per International Conference on Harmonization guidelines. The analytes were extracted in rabbit plasma using liquid-liquid extraction technique and analyzed at 247 nm after separation through a reverse-phase C18 column. The isocratic mobile phase used is a mixture of acetonitrile, water and glacial acetic acid in the ratio of 60:40:1 v/v/v maintained at pH 3.4. All calibration curves showed a good linear relationship (r > 0.995) within the test range. Precision was evaluated by intra- and interday tests with RSDs <1.91% and accuracy showed validated recoveries of 86.20-101.11%. Based on our results, the developed method features good quantification parameters and can serve as an effective quality control method for the standardization of drugs.

Recent bioanalytical methods for the isolation of bioactive natural products from genus Codonopsis.

INTRODUCTION: Chromatography and spectroscopy are nowadays well-validated techniques allowing to isolate and purify different class of natural products from the genus Codonopsis. Several categories of phytochemicals with drug like properties have been selectively extracted, isolated, characterised by this methodology. OBJECTIVES: The present review aims to provide up-to-date and comprehensive information on the chromatography, phytochemistry and pharmacology of natural products of Codonopsis with an emphasis on the search for natural products having various biological activities and the semi-synthetic derivatives of bioactive ones and to highlight current gaps in knowledge. MATERIALS AND METHODS: A literature search was performed in the SciFinder Scholar, PubMed, Medline, and Scopus databases. RESULTS: During the period covered in this review, several classes of compounds have been reported from genus Codonopsis. Codonopsis pilosula and Codonopsis lanceolata are the most popular in the genus especially as per phytochemical and bioactive studies. Phytochemical investigation demonstrates that Codonopsis species contain mainly xanthones, flavonoids, alkaloids, polyacetylenes, phenylpropanoids, triterpenoids and polysaccharides, which contribute to numerous bioactivities. The major bioactive compounds isolated were used for semi-synthetic modification to increase the chance to discover lead compound. CONCLUSIONS: It can be concluded that genus Codonopsis has been used as traditional medicines and food materials around the world over years due to chemical constituents with diverse structural types, exhibiting extensive pharmacological activities in immune system, blood system, cardiovascular system, central nervous system, digestive system, and so forth, with almost no obvious toxicity and side effect. Therefore, Codonopsis can be used as a promising ethnopharmacological plant source.

Seasonal influenza vaccine uptake among healthcare workers in tertiary care hospitals, Bangladesh: Study protocol for influenza vaccine supply and awareness intervention.

BACKGROUND: Healthcare workers (HCWs), such as doctors, nurses, and support staffs involved in direct or indirect patient care, are at increased risk of influenza virus infections due to occupational exposures. Vaccination is the most effective way to prevent influenza. Despite the World Health Organization (WHO) recommendations, Bangladesh lacks a seasonal influenza vaccination policy for HCWs, and thus vaccination rates remain low. The current project aims to investigate the effect of interventions on influenza vaccine awareness and availability of vaccine supply, explore HCWs' knowledge and perceptions about influenza vaccination, understand the barriers and motivators for influenza vaccine uptake, and understand policymakers' views on the practicality of influenza vaccination among HCWs. METHOD: We will conduct the study at four tertiary care teaching hospitals in Bangladesh, using a cluster randomized controlled trial approach, with the hospital as the unit of randomization and intervention. The study population will include all types of HCWs.The four different types of intervention will be randomly allocated and implemented in four study hospitals separately. The four interventions will be: i) ensuring the availability of influenza vaccine supply; ii) developing influenza vaccine awareness; iii) both ensuring influenza vaccine supply and developing influenza vaccine awareness and iv) control arm with no intervention. Both quantitative and qualitative approaches will be applied to assess the intervention effect. We will estimate the Difference in Differences (DID) with 95% CI of the proportion of vaccine uptake between each intervention and control (non-intervention) arm, adjusting for the clustering effect. The qualitative data will be summarised using a framework matrix method. DISCUSSION: The results of this study will inform the development and implementation of a context-specific strategy to enhance influenza vaccination rates among Bangladeshi HCWs. TRIAL REGISTRATION: Clinicaltrials.gov NCT05521763. Version 2.0 was registered in September 2022, and the first participant enrolled in March 2022. Retrospectively registered.

Development, method validation and simultaneous quantification of eleven bioactive natural products from high-altitude medicinal plant by high-performance liquid chromatography.

Herein, a novel, rapid, reliable, simple method validation and simultaneous quantification of 11 bioactive compounds (mostly xanthones) have been described. International Conference on Harmonization guidelines were used for the analytical method validation. Good linearity, repeatability, intra- and inter-day precision, accuracy and reliability were well-illuminated in the method validation procedure. The calibration curves showed a good linear relationship (r > 0.999) within test range. Precision was evaluated by intra- and inter-day tests with relative standard deviation <2.79% and accuracy validation recovery of 74.16%-91.84%. On quantification study, the validated method described the high content of bioactive xanthone derivatives, including 1-hydroxy-3, 5-dimethoxyxanthone (7), 2-(allyloxy)-8-hydroxy-1, 6-dimethoxyxanthone (6) 1, 7, 8-trihydroxy-3-methoxyxanthone (9) and Coxanthone E (5) in Codonopsis ovata, which is advantageous given the numerous pharmacological and biological effects associated with these compounds, which mostly exhibit anti-cancerous, antioxidant, anti-inflammatory, anti-mutagenic and anti-obesity effects. The bulk abundance of these compounds can also be used for further modification to produce better lead molecules for drug discovery with low toxicity and high potency. The proposed method makes it possible to simultaneously determine all bioactive compounds in one run and can be extended to marker-based standardization of herbal formulations in medicinal and pharmaceutical industries.

Risk assessment, development and validation of a GC-ECD-based method for the quantification of cypermethrin from green pea.

The present work describes the persistence, dissipation behaviour, half-life, risk assessment and novel gas chromatography method for the residue estimation of cypermethrin in green pea by spraying cypermethrin 10EC at 50 g a.i. ha-1 at fruiting stage followed by another application at a 10 day interval. The sample extraction and cleanup was followed bya modified quick, easy, cheap, effective, rugged, and safe method, and the residues of cypermethrin were determined using a validated gas chromatography method. The initial deposits were found to be 1.21 mg kg-1 following the application of insecticide at 50 g a.i. ha-1 . Cypermethrin residues declined to below the detection limit of 0.05 mg kg-1 after 15 days at the recommended dosage. The half-life of cypermethrin was 2.66 days at 50 g a.i. ha-1 . For risk assessment studies, the waiting period of 15 days is recommended as safe for consumption for the insecticide. The GC-ECD method was validated according to the SANTE guidelines by various analytical parameters including linearity, accuracy, detection and quantification limits. The developed method is simple, selective and repeatable, and can be used for the standardization of pesticides on fruits and vegetables.

Dissipation and gas chromatographic method for the determination of profenofos residues in/on green pea and cucumber.

Herein we report a novel, accurate and cost-effective gas chromatography method for the determination of average deposits of profenofos on green pea and cucumber following good agricultural practices. Additionally the risk assessment, dissipation and waiting period for profenofos were determined. The average initial deposits (2 h after spraying) of profenofos in/on green pea and cucumber were 3.41 and 3.62 mg kg-1 respectively following two applications at a 10 day interval of profenofos 50EC formulation. Profenofos residues on both of the substrates were below the detection limit of 0.05 mg kg-1 after 20 days at the recommended dosage. For risk assessment studies, the 20th day will be safe for consumers for consumption of green peas. The gas chromatography method was validated according to the SANTE guidelines using the various analytical parameters: linearity, accuracy, detection and quantification limits. The developed method is simple, selective and repeatable and can be extended for profenofos-based standardization of pesticide formulations for green pea/cucumber and their use as pesticides.

Foraging behavior and bait station preference in scavenging termite, Odontotermes obesus (Blattodea: Termitidae).

Termites are a significant pest of buildings, agriculture, and trees, and are mainly controlled by baiting. However, baiting systems are available for only lower termites (Rhinotermitidae) not for higher termites (Termitidae). Termite foraging behavior associated with baiting systems varies among species and families, and plays a significant role in baiting success. Here, foraging behavior of Odontotermes obesus (Blattodea: Termitidae: Macrotermitinae), a fungus-growing higher termite, was investigated relative to three bait-station sizes (small, medium, and large) containing different quantities of food. Significantly more workers recruited to large stations (470/station) compared to medium (246/station) and small (124/station) stations. Abundance of O. obesus in large and medium stations significantly positively correlated with relative humidity whereas negative but non-significant correlations were observed with temperature in large and medium stations. Total and continuous contacts with the stations increased with time and were greater in large stations. Station abandonment due to disturbance was significantly less in large stations (3%) followed by medium (9%) and small stations (20%). Our results suggest that large stations (≈8 litres volume) work best for population management of O. obesus and other related fungus-growing higher termites.

Assessment of immunity to polio among Rohingya children in Cox's Bazar, Bangladesh, 2018: A cross-sectional survey.

BACKGROUND: We performed a cross-sectional survey in April-May 2018 among Rohingya in Cox's Bazar, Bangladesh, to assess polio immunity and inform vaccination strategies. METHODS AND FINDINGS: Rohingya children aged 1-6 years (younger group) and 7-14 years (older group) were selected using multi-stage cluster sampling in makeshift settlements and simple random sampling in Nayapara registered camp. Surveyors asked parents/caregivers if the child received any oral poliovirus vaccine (OPV) in Myanmar and, for younger children, if the child received vaccine in any of the 5 campaigns delivering bivalent OPV (serotypes 1 and 3) conducted during September 2017-April 2018 in Cox's Bazar. Dried blood spot (DBS) specimens were tested for neutralizing antibodies to poliovirus types 1, 2, and 3 in 580 younger and 297 older children. Titers ≥ 1:8 were considered protective. Among 632 children (335 aged 1-6 years, 297 aged 7-14 years) enrolled in the study in makeshift settlements, 51% were male and 89% had arrived after August 9, 2017. Among 245 children (all aged 1-6 years) enrolled in the study in Nayapara, 54% were male and 10% had arrived after August 9, 2017. Among younger children, 74% in makeshift settlements and 92% in Nayapara received >3 bivalent OPV doses in campaigns. Type 1 seroprevalence was 85% (95% CI 80%-89%) among younger children and 91% (95% CI 86%-95%) among older children in makeshift settlements, and 92% (88%-95%) among younger children in Nayapara. Type 2 seroprevalence was lower among younger children than older children in makeshift settlements (74% [95% CI 68%-79%] versus 97% [95% CI 94%-99%], p < 0.001), and was 69% (95% CI 63%-74%) among younger children in Nayapara. Type 3 seroprevalence was below 75% for both age groups and areas. The limitations of this study are unknown routine immunization history and poor retention of vaccination cards. CONCLUSIONS: Younger Rohingya children had immunity gaps to all 3 polio serotypes and should be targeted by future campaigns and catch-up routine immunization. DBS collection can enhance the reliability of assessments of outbreak risk and vaccination strategy impact in emergency settings.

Vaccination coverage survey and seroprevalence among forcibly displaced Rohingya children, Cox's Bazar, Bangladesh, 2018: A cross-sectional study.

BACKGROUND: During August 2017-January 2018, more than 700,000 forcibly displaced Rohingyas crossed into Cox's Bazar, Bangladesh. In response to measles and diphtheria cases, first documented in September and November 2017, respectively, vaccination campaigns targeting children <15 years old were mobilized during September 2017-March 2018. However, in a rapidly evolving emergency situation, poor sanitation, malnutrition, overcrowding, and lack of access to safe water and healthcare can increase susceptibility to infectious diseases, particularly among children. We aimed to estimate population immunity to vaccine-preventable diseases (VPDs) after vaccination activities in the camps to identify any remaining immunity gaps among Rohingya children. METHODS AND FINDINGS: We conducted a cross-sectional serologic and vaccination coverage survey in Nayapara Registered Refugee Camp ("Nayapara") and makeshift settlements (MSs) April 28, 2018 to May 31, 2018, among 930 children aged 6 months to 14 years. MSs are informal, self-settled areas with a population of more than 850,000, the majority of whom arrived after August 2017, whereas Nayapara is a registered camp and has better infrastructure than MSs, including provision of routine immunization services. Households were identified using simple random sampling (SRS) in Nayapara and multistage cluster sampling in MSs (because household lists were unavailable). Dried blood spots (DBSs) were collected to estimate seroprotection against measles, rubella, diphtheria, and tetanus, using Luminex multiplex bead assay (MBA). Caregiver interviews assessed vaccination campaign participation using vaccination card or recall. In Nayapara, 273 children aged 1 to 6 years participated; 46% were female and 88% were registered refugees. In MSs, 358 children aged 1 to 6 years and 299 children aged 7 to 14 years participated; 48% of all children in MSs were female, and none were registered refugees. In Nayapara, estimated seroprotection among 1- to 6-year-olds was high for measles, rubella, diphtheria, and tetanus (91%-98%; 95% confidence interval [CI] 87%-99%); children >6 years were not assessed. In MSs, measles seroprotection was similarly high among 1- to 6-year-olds and 7- to 14-year-olds (91% [95% CI 86%-94%] and 99% [95% CI 96%-100%], respectively, p < 0.001). Rubella and diphtheria seroprotection in MSs were significantly lower among 1- to 6-year-olds (84% [95% CI 79%-88%] and 63% [95% CI 56%-70%]) compared to 7- to 14-year-olds (96% [95% CI 90%-98%] and 77% [95% CI 69%-84%]) (p < 0.001). Tetanus seroprevalence was similar among 1- to 6-year-olds and 7- to 14-year-olds (76% [95% CI 69%-81%] and 84% [95% CI 77%-89%], respectively; p = 0.07). Vaccination campaign coverage was consistent with seroprotection in both camps. However, nonresponse, the main limitation of the study, may have biased the seroprotection and campaign coverage results. CONCLUSIONS: In this study, we observed that despite multiple vaccination campaigns, immunity gaps exist among children in MSs, particularly for diphtheria, which requires serial vaccinations to achieve maximum protection. Therefore, an additional tetanus-diphtheria campaign may be warranted in MSs to address these remaining immunity gaps. Rapid scale-up and strengthening of routine immunization services to reach children and to deliver missed doses to older children is also critically needed to close immunity gaps and prevent future outbreaks.

Development of an RNA Strand-Specific Hybridization Assay To Differentiate Replicating versus Nonreplicating Influenza A Viruses.

Replication of influenza A virus (IAV) from negative-sense viral RNA (vRNA) requires the generation of positive-sense RNA (+RNA). Most molecular assays, such as conventional real-time reverse transcriptase PCR (rRT-PCR), detect total RNA in a sample without differentiating vRNA from +RNA. These assays are not designed to distinguish IAV infection versus exposure of an individual to an environment enriched with IAVs but wherein no viral replication occurs. We therefore developed a strand-specific hybridization (SSH) assay that differentiates between vRNA and +RNA and quantifies relative levels of each RNA species. The SSH assay exhibited a linearity of 7 logs with a lower limit of detection of 6.0 × 102 copies of molecules per reaction. No signal was detected in samples with a high load of nontarget template or influenza B virus, demonstrating assay specificity. IAV +RNA was detected 2 to 4 h postinoculation of MDCK cells, whereas synthesis of cold-adapted IAV +RNA was significantly impaired at 37°C. The SSH assay was then used to test IAV rRT-PCR positive nasopharyngeal specimens collected from individuals exposed to IAV at swine exhibitions (n = 7) or while working at live bird markets (n = 2). The SSH assay was able to differentiate vRNA and +RNA in samples collected from infected, symptomatic individuals versus individuals who were exposed to IAV in the environment but had no active viral replication. Data generated with this technique, especially when coupled with clinical data and assessment of seroconversion, will facilitate differentiation of actual IAV infection with replicating virus versus individuals exposed to high levels of environmental contamination but without virus infection.

Screening for malaria antigen and anti-malarial IgG antibody in forcibly-displaced Myanmar nationals: Cox's Bazar district, Bangladesh, 2018.

BACKGROUND: Several refugee settlements in Bangladesh have provided housing and medical care for the forcibly-displaced Myanmar nationals (FDMN, also known as Rohingya) population. The identification of malaria infection status in the refugee settlements is useful in treating infected persons and in developing malaria prevention recommendations. Assays for Plasmodium antigens and human IgG against Plasmodium parasites can be used as indicators to determine malaria infection status and exposure. METHODS: Dried blood spot (DBS) samples (N = 1239) from a household survey performed April-May 2018 in three settlements in Cox's Bazar district, Bangladesh were utilized for a sample population of children from ages 1-14 years of age. The samples were tested using a bead-based multiplex antigen assay for presence of the pan-Plasmodium antigen aldolase as well as Plasmodium falciparum histidine rich protein 2 (HRP2). A bead-based multiplex assay was also used to measure human IgG antibody response to P. falciparum, Plasmodium malariae, and Plasmodium vivax merozoite surface protein 1 antigen (MSP1) isoforms, and P. falciparum antigens LSA1, CSP, and GLURP-R0. RESULTS: There were no detectable Plasmodium antigens in any samples, suggesting no active malaria parasite infections in the tested children. IgG seroprevalence was highest to P. vivax (3.1%), but this was not significantly different from the percentages of children antibody responses to P. falciparum (2.1%) and P. malariae (1.8%). The likelihood of an anti-Plasmodium IgG response increased with age for all three malaria species. Evidence of exposure to any malaria species was highest for children residing 8-10 months in the settlements, and was lower for children arriving before and after this period of time. CONCLUSIONS: Absence of Plasmodium antigen in this population provides evidence that children in these three Bangladeshi refugee settlements did not have malaria at time of sampling. Higher rates of anti-malarial IgG carriage from children who were leaving Myanmar during the malaria high-transmission season indicate these migrant populations were likely at increased risk of malaria exposure during their transit.

Method validation and simultaneous quantification of eight organochlorines/organophosphates in apple by gas chromatography.

BACKGROUND: The increasing and extensive use of pesticides worldwide has resulted in a significant loss of non-target populations particularly humans by direct or indirect exposures. Also, various methods have been used for the estimation of pesticide residues in fruits and vegetables from recent past which are either tedious, time consuming or expensive. Therefore, the present study was performed to determine the pesticide residues from apple by simple and novel validated gas chromatography. RESULTS: A novel, accurate, ecofriendly and cost-effective gas chromatography method was developed for simultaneous quantification of eight pesticides, namely chlorpyrifos-methyl (1), chlorpyrifos (2), quinolphos (3), profenofos (4), myclobutnil (5), ethion (6), fenpropathrin (7) and cypermethrin (8). The developed method was validated as per the SANTE guidelines. All calibration curves showed a good linear relationship (r > 0.99) within the test range. Precision was evaluated by intra- and inter-day tests with relative standard deviations (RSDs) < 2.0%, recovery in between 70% and 120% with RSDs < 2.00%. CONCLUSION: The results demonstrate that the concentration of pesticides 1 to 8 were found below the detectable limit. Method validation parameters like linearity, precision, accuracy, specificity, robustness, detection and quantification limits were found within the acceptable range. The proposed method makes it possible to determine simultaneously pesticides 1-8 in one run which can be extended for residue-based standardization of pesticides from apple and other fruits and vegetables. © 2019 Society of Chemical Industry.

Risk assessment, dissipation behavior and persistence of quinalphos in/on green pea by gas chromatography with electron capture detector.

Chemical investigation was carried out to examine the risk assessment, dissipation behavior, persistence, and half-life period of quinalphos in/on green pea fruit by spraying quinalphos at fruiting stage followed by another application after 10-day interval. The samples were extracted by using the quick, easy, cheap, effective, rugged, and safe method, and the residues of quinalphos were analyzed by gas chromatography with electron capture detector. Herein, we report a novel, accurate, and cost-effective gas chromatography method for the determination of average deposits of quinalphos in/on green pea. The initial deposits and half-life of quinalphos were found to be 1.20 mg/kg and 2.77 days, respectively, following the application of insecticide. Residues of quinalphos reached below detection limit of 0.05 mg/kg after 10 days at recommended dosage. For risk assessment studies, the tenth day will be safe for consumers for consumption of green pea. The developed method is simple, selective, and repeatable, and it can be extended for quinalphos-based standardization of herbal formulations containing green pea and its use in pesticide industries.

Quantification, dissipation behavior and risk assessment of ethion in green pea by gas chromatography-electron capture detector.

Residue investigation was carried out to scrutinize the persistence, dissipation behavior, half-life, and risk assessment of ethion on green pea fruit by spraying ethion at the fruiting stage followed by another application at 10 day intervals. The samples were extracted by using a quick, easy, low-cost, effective, rugged, and safe method, and the residues of ethion were analyzed by gas chromatography with electron capture detection. Here we report a novel, accurate, and cost-effective gas chromatography method for the determination of average deposits of ethion on green pea. The initial deposits were found to be 4.65 mg/kg following the application of insecticide. Residues of ethion reached below the detection limit of 0.10 mg/kg after 25 days at recommended dosage. The half-life of ethion was found to be 4.62 days. For risk assessment studies, the 25th day will be safe for consumers for the consumption of green peas. The developed method is simple, sensitive, selective, and repeatable and can be extended for ethion-based standardization of herbal formulations containing green pea and its use in pesticide industries.