Mean Residue Levels Research Articles

Development and validation of a modified QuEChERS method coupled with LC-MS/MS for simultaneous determination of difenoconazole, dimethoate, pymetrozine, and chlorantraniliprole in brinjal collected from fields and markets places to assess human health risk

An effective and sensitive analytical method was developed to quantify the most common pesticide residues (difenoconazole, dimethoate, pymetrozine, and chlorantraniliprole) used for brinjal cultivation in Bangladesh. The quantification of the analytes was done using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The samples were extracted using a modified QuEChERS method and followed by purification with dispersive solid phase extraction (d-SPE) sorbents (PSA, GCB, and C18). Matrix-matched calibration with a regression coefficient R2 ≥ 0.9964 were used to minimize the brinjal matrix effect. The method was validated in quintuple (n = 5) at five different spiked levels (8–400 μg/kg) having recoveries in the range of 70.3–113.2% with relative standard deviations RSDs ≤6.8%, limits of detection (LOD) and limits of quantification (LOQ) was in the range of 0.15–0.66 μg/kg and 0.4–2.0 μg/kg, respectively, for the four analytes. A total 100 samples (50 samples directly from fields of Jessore district, Bangladesh and 50 samples from local market of Dhaka, Bangladesh) were collected to analyse the pesticides residue. The result showed that pesticides residue was found in both the field and market collected samples, 54% and 38%, respectively. The overall mean residue levels of four pesticides in field samples were significantly higher than those of market samples. Moreover, 20% of the field samples and 10% of the market samples had dimethoate residues, which were the most abundant among the four analytes and it ranged from 0.017 to 0.252 mg/kg. In terms of health risk assessments, dimethoate showed the highest estimated daily intake (EDI) and hazard quotient (HQ) values that are 3.02 × 10−5 mg/kg/day and 1.51%, respectively, in field samples. Till now, there have been no regulations or guidelines for the maximum admissible pesticide residue in Bangladesh. Therefore, the above findings will be an initial step for the regulatory authorities of Bangladesh to implement regulations and guidelines for pesticide usage.

Optimising weighted averaging for auditory brainstem response detection

The auditory brainstem response (ABR) is a clinical test used to evaluate hearing objectively. The aim of this study was to optimise weighted averaging for both residual noise reduction and also for objective ABR detection using the Fmp statistical test. Analyses were performed using no-stimulus EEG background activity recorded from 15 participants and simulated “response present” data (4,602 ensembles in total). Different approaches for estimating the variance of the noise within each block were compared, as was the effect of the number of recording epochs in each block when calculating and applying the weights. The “VAR Whole Block” method was found to be more effective than the “VAR MP” method at estimating the noise level, especially for smaller block sizes (2–10 epochs). Caution should be exerted when selecting recording parameters for use with weighted averaging as an inflation in the “response absent” Fmp statistic was observed using small block sizes (relative to unweighted averaging); this may be due to a bias in the Fmp statistic observed as a result of the combined effects of the finite Fmp analysis window length and the high-pass filter setting. Optimised weighted averaging was effective in reducing the mean residual noise level in the averaged waveform, leading to improved ABR detection. Further work is required to optimise the Fmp analysis window length, recording settings, and weighted averaging parameters in combination, using a large clinical dataset.

Pesticide Residues in Vegetables and Fruits from Farmer Markets and Associated Dietary Risks.

The use of pesticides leads to an increase in agricultural production but also causes harmful effects on human health when excessively used. For safe consumption, pesticide residues should be below the maximum residual limits (MRLs). In this study, the residual levels of pesticides in vegetables and fruits collected from farmers' markets in Sharkia Governorate, Egypt were investigated using LC-MS/MS and GC-MS/MS. A total number of 40 pesticides were detected in the tested vegetable and fruit samples. Insecticides were the highest group in detection frequency with 85% and 69% appearance in vegetables and fruits, respectively. Cucumber and apple samples were found to have the highest number of pesticide residues. The mean residue levels ranged from 7 to 951 µg kg-1 (in vegetable samples) and from 8 to 775 µg kg-1 (in fruit samples). It was found that 35 (40.7%) out of 86 pesticide residues detected in vegetables and 35 (38.9%) out of 90 pesticide residues detected in fruits exceeded MRLs. Results for lambda-cyhalothrin, fipronil, dimothoate, and omethoate in spinach, zucchini, kaki, and strawberry, respectively, can cause acute or chronic risks when consumed at 0.1 and 0.2 kg day-1. Therefore, it is necessary for food safety and security to continuously monitor pesticide residues in fruits and vegetables in markets.

P439 Stability of subcutaneous serum IFX (CTP13) levels between two injections and over two successive cycles in patients with Crohn’s disease

Abstract Background Under IFX sc, we do not know if there is a residual level of IFX. The aim of this work was to investigate this point by analyzing the intra-individual variability of the serum level of IFX sc. Methods This was an observational, prospective study that included patients with CD undergoing maintenance treatment with IFX sc (120mg every, 14 days). Patients had IFX determinations (i Track, 10; Theradiag (France) at visit, 1 (day, 4 to, 6 after SC injection), visit, 2 (day, 7 to, 9 after sc injection) and visit, 3 (day, 13 to, 14 after sc injection) on two consecutive cycles. The first determinations were made only after, 8 weeks of switching from IV to SC. All patients at inclusion were in clinical remission (CDAI <, 150) with calprotectin levels <, 250 µg/g stool. Results 20 patients (mean age:, 36 years, sex ratio M/F:, 1, mean duration of IFX IV:, 16 months) were included, i.e. meaning, 120 determinations., 8 patients were treated in combination with thiopurines. Mean residual levels before switch to sc were, 3.9 +/-1.2 µg/mL. Mean intraindividual levels between the two cycles were comparable (Visit, 1: cycle, 1:, 11.1 +/-, 4.4 µg/mL, cycle, 2:, 11.6 +/-, 4.6 µg/mL; p=0.65; Visit, 2: cycle, 1:, 12.0 +/-, 5.1 µg/mL, cycle, 2:, 11.3 +/-4.9 µg/mL; p=0.25; Visit, 3 cycle, 1:, 11.0 +/-4., 7 µg/mL, cycle, 2:, 10.9 +/-, 4.2 µg/mL; p=0.21. Serum IFX sc levels remained stable over the, 14 days between the two SC injections (p=0.36). Mean IFX levels at any dosing time were comparable in patients with and without thiopurines (IFX sc monotherapy: mean:, 11.5 +/-, 5.5 µg/mL versus IFX sc with thiopurines: mean:, 11.8 +/-, 4.6 µg/mL, p=0.54). Finally, residual IFX IV levels before switch did not influence the results of IFX sc serum concentrations (p=NS). Conclusion Measure of IFX levels for IFX SC can be proposed at any time between two injections. No residual levels were found. These data are important for our clinical practice.

The residual nitrate and nitrite levels in meat products in Iran: A systematic review, meta-analysis and health risk assessment

This study was designed to investigate the mean residual nitrite and nitrate levels in meat products, in Iran and to evaluate their health-related risks. After reviewing 799 studies, 15 were finally selected, their information was recorded and examined using Stata software. The results of the present study show that the mean residual nitrite and nitrate levels in meat products was about 55.18 and 95.09 ppm, respectively. The residual nitrite level is different in various meat products, so that the residual nitrite level in sausages and kielbasa is 54.52 and 56.87 ppm, respectively. Also, the present study shows that the mean residual nitrate level in sausages and kielbasa was 77.21 and 121.49 ppm, respectively. Health Risk Index (HRI) of nitrite and nitrate were 0.1541 and 0.0050, respectively, which were lower than 1 value. Therefore, there is no considerable carcinogenic risk for consumers in Iran. Taking together, these residues must be continuously monitored by relevant authorities.

Energy Efficient Data Gathering in IoT Networks With Heterogeneous Traffic for Remote Area Surveillance Applications: A Cross Layer Approach

In this paper, the problem of energy-efficient data gathering in an Internet of Things (IoT) based remote area surveillance application is addressed by designing a suitable MAC layer uplink solution. We follow the 3GPP specified scheduled access scheme for narrowband IoT (NB-IoT) and consider presence of both delay sensitive and delay tolerant traffic in the network. First, we present a mixed integer non-linear programming (MINLP) based optimization framework to minimize the IoT devices’ cumulative transmission energy per uplink frame under the constraints of finite resource blocks, mean queue stability and residual energy levels of IoT nodes. A cross layer approach has been adopted. Precisely, using Lyapunov optimization, we propose a dynamic, distributed transmit power allocation for IoT nodes and a centralized node scheduling scheme. Further, assuming Poisson model for traffic generation at delay tolerant traffic generating nodes, we suggest a distributed probabilistic sleep scheduling scheme to improve the average delay experience of delay sensitive traffic while improving the overall energy conservation. Simulation results suggest impressive performance of our proposed solution over the existing uplink solution for NB-IoT, in terms of delay experience of delay sensitive traffic, buffer length requirement and nodes’ total energy consumption at high traffic load.

Residues of streptomycin antibiotic in commercial layers in Abeokuta and Ibadan metropolis

Old layers sold for human consumption in six open markets in Abeokuta and Ibadan metropolis of Ogun and Oyo States of Nigeria were analyzed for the presence of residues of streptomycin antibiotic. One hundred and twenty samples comprising of muscle (thigh and breast), liver and kidney tissues were subjected to microbiological assay technique for the detection of residues of the antibiotic. The assay was done on antibiotic medium 5 agar with Bacillus subtilis (ATCC 6633) organism. Results showed that 34.17% of the sampled birds were positive for the presence of streptomycin antibiotic. The concentration of the residues ranged between 0.18µg/g and 0.91µg/g. The mean residue levels recorded among the organs are not significantly different (P>0.05). Some of the muscle samples recorded residue concentration levels higher than the W.H.O recommended maximum residue level for streptomycin antibiotic in muscle tissue of food animals. In view of the importance of antibiotics in the treatment of bacterial diseases in both human and animals, it is advocated that the use of these drugs in food animals be done judiciously.

Multi-residue Analysis of Organochlorine Pesticides in Cocoa Beans (Theobroma cacao) and Soils from Ondo, Nigeria

Organochlorine pesticides (OCPs) residues were determined in a total of 160 samples comprising of cocoa beans and soil collected from four major cocoa farms in Ondo, Nigeria. The residues were extracted with dichloromethane, cleaned up by column chromatography and analysed with Gas Chromatography-Electron Capture Detector (GC-ECD). In the analysed cocoa samples, endrin and endosulfan I had the highest incidence of occurrence of 93% and 89%, respectively while lindane and heptachlor had the least occurrence of 19%. High incidences of occurrence in the soil samples were observed in endrin (93%) and endosulfan I (94%) while the least occurrence was α-HCH (13%). The total residual concentrations of the OCPs were higher in the cocoa samples compared to the soil samples. The mean residual levels of HCHs (α, β, δ) aldrin, dieldrin, endrin and endosulfan I and cis-permethrin in the cocoa samples were above Maximum Residual Limits (MRL) established by WHO/FAO while aldrin, dieldrin, endrin, endosulfans in the soil sample analysed were above MRL established by Netherlands. Bioaccumulation factor > 1 was recorded in most of the cocoa samples from the different farms especially for endrin, dieldrin, endosulfan I and trans-permethrin. This gives cause for concern considering the adverse health hazards pose by these pesticides.

Effectiveness of a decontamination procedure in a pharmacy buffer room contaminated by 5 antineoplastic agents.

Healthcare facilities are obligated to implement strategies to protect healthcare workers from exposure to hazardous drugs, including any real or potential risk from contaminated surfaces. Guidelines are broad and lack sufficient detail for healthcare facilities to establish clear effectiveness targets for their decontamination procedures. Our goal in this analysis was to measure the effectiveness of a decontamination procedure in a pharmacy buffer room contaminated with 5 antineoplastic drugs. Six rounds of contamination, decontamination, and wipe sampling were performed in a pharmacy buffer room designated for hazardous drug (HD) compounding. Ten locations in the buffer room were contaminated with 5-fluorouracil, carboplatin, cyclophosphamide, paclitaxel, and doxorubicin. Pharmacy staff were blinded to contamination sites. After contamination, 3 pharmacy technicians following the same decontamination procedure decontaminated the buffer room. To assess the impact of decontamination, residual hazardous drug levels were assessed after contamination and after decontamination using a commercially available wipe sampling product. The mean (SD) residual contamination levels for the 239 wipe samples taken before and after decontamination were 63 (60) ng and 3.9 (8.2) ng, respectively, representing a 94% reduction in residual HD contamination. Residual contamination was not detectable (<5 ng) in 221 (~93%) of the samples after decontamination. The employed decontamination procedures effectively reduced residual HD surface contamination.

Evaluating the Residual Nitrite Concentrations of Bacon in the United Kingdom.

The preservative sodium nitrite is added to processed meat with the intention of preventing the growth of Clostridium botulinum, but this also influences product flavour and colour. The World Health Organisation has declared nitrites to be ‘probably carcinogenic’. Use is permitted by the European Union but its addition is limited to 100 mg/kg in all processed meat, except bacon, which is limited to 175 mg/kg. At present, there is no independent peer-reviewed literature assessing the residual nitrite levels in bacon in the United Kingdom. Furthermore, this is the largest study of residual nitrite concentrations in bacon that has ever been conducted. A total of 89 different commercially available bacon samples were collected, and analysed using flow injection analysis to determine their residual nitrite content. The mean residual nitrite concentration for all bacon samples was 10.80 mg/kg. Residual nitrite levels did not differ between smoked and unsmoked bacon. Middle cut bacon (26.00 mg/kg) had significantly higher residual nitrite concentrations than back bacon (8.87 mg/kg; p = 0.027), and medallion bacon (4.47 mg/kg; p = 0.008). This study shows that there is large variation in the mean residual nitrite levels of bacon sold in the UK and all the reported values are within current regulatory limits. Despite this, it appears that many manufacturers could decrease the amount that they are currently using in their products.

Occurrence of Carbaryl, DDT and Deltamethrin Residues in Bovine Milk in Chhattisgarh, India and Risk Assessment to Human Health

The aim of this study was to determine the occurrence of pesticide residues in bovine milk and associated health risks in human. To assess the pesticide residues, a total of 200 milk samples were analyzed using High Performance Liquid Chromatography (HPLC) with Photo Diode Array Detector (PDA).The residues of carbaryl, 4’4’ DDT and deltamethrin pesticides were found in the 27.5%, 11% and 5% milk samples, respectively. The spatial distribution of pesticide residues in milk samples indicated that carbaryl was wide spread over the entire study area. The non-significance differences in mean residual concentrations of all three pesticides in cow and buffalo milk samples were recorded. The human health risk assessment in terms of non-carcinogenic and carcinogenic health hazard was calculated based on both lower bound [LB (mean residue levels)] and upper bound [UB (95th percentile level)] limits at current levels of pesticides in bovine milk samples. The estimated average daily dietary intake (EADDI) of studied pesticides was found below the acceptable dietary intake (ADI) for both adult and children, at mean as well as 95th percentile upper bound (UB) levels. The values suggesting lower carcinogenic and non-carcinogenic health risk to adult however children are at greater health risk.

Investigation of the distribution of anticoagulant rodenticide residues in red fox (Vulpes vulpes) livers to ensure optimum sampling protocol

Abstract The lobular distribution of 9 different anticoagulant rodenticide (AR) residues in the liver of a sentinel predator/scavenger i.e. the red fox (Vulpes vulpes) was determined following multi-residue analysis using Ultra (High) Performance Liquid Chromatography tandem Mass Spectrometry (UHPLC-MS/MS). The aim of the study was to address concerns that if distribution of AR residues in the liver was significantly heterogeneous, analysis of random sub-samples or finite remnants of liver could result in false negatives or lead to incorrect toxicological diagnoses. Intact livers excised from animals shot as part of routine legal pest control activities in Scotland during 2018 and 2019 were sub-sectioned and the lobular concentration of AR residues was investigated. Analysis of individual lobes from 10 different fox livers revealed that AR residues initially detected in a randomly selected small portion of liver tissue were present throughout the liver. Also, in cases where AR residues were not found in the initial randomly selected portion, they were not found in the subsequent more detailed examination. The limit of quantitation was 3 μg kg‐1 and AR residue concentrations ranged from 3 to 885 μg kg−1. Statistical analysis of variance (ANOVA) was performed on the eight and six out of ten livers that tested positive for bromadiolone and brodifacoum, respectively. No statistical evidence was found of differences in mean residue levels of bromadiolone throughout the liver i.e. within and between liver lobes. However, brodifacoum showed a statistically significant difference (p

Occurrence of seventeen veterinary antibiotics and resistant bacterias in manure-fertilized vegetable farm soil in four provinces of China

This study focused on the occurrence of seventeen veterinary antibiotics and six resistant bacterias in soils from the vegetable farms fertilized with animal manure in China. Seventeen veterinary antibiotics, including sulfonamides, quinolones, tetracyclines, macrolides and amphenicols, were detected by high performance liquid chromatography/tandem mass spectrometer in all the 53 soil samples collected in four provinces during August 2016. The concentrations of target antibiotics in the soil samples ranged from not detectable to 415.00 μg/kg dry weight with the mean residual levels of the five classes followed order: tetracyclines (82.75 μg/kg) > quinolones (12.78 μg/kg) > macrolides (12.24 μg/kg) > sulfonamides (2.61 μg/kg) > amphenicols (0.06 μg/kg). Moreover, the highest antibiotic levels were found mainly in soil from organic vegetable farms. Risk assessment by using the methods of risk quotient, suggested that oxytetracycline, chlortetracycline, enrofloxacin and ciprofloxacin could pose severe ecological risk in sampled soils. Resistant strains were isolated in 30 samples, with Escherichia coli and Klebsiella pneumonia found the dominant bacterial hosts with resistance genes. Antibiotic resistance genes, including tetA, tetB, qnrS, oqxA, sul1, sul2, ermA and floR, were detected in the strains resistant to: tetracyclines, quinolones, sulfonamides, macrolides and amphenicols resistance, respectively. Overall, there was a correlation between the results of antibiotic risk assessment with the detection of resistance genes from isolated strains in the soils.

Effects of processing and cooking on the reduction of dinotefuran concentration in Japanese rice samples

ABSTRACTDinotefuran is an insecticide belonging to the neonicotinoid class, which is frequently used to control pests in paddy rice owing to its permeability and effectiveness against sucking insects. Since 2002, this insecticide has been commercially available in Japan, and has become controversial due to its high detection frequency in brown rice for primary consumption. In this study, the effects of processing and cooking on the reduction of dinotefuran residues in commercially available brown rice were investigated. Boiled rice is difficult to homogenise and extract with acetonitrile. Using pre-freezing and cryogenic milling with powdered dry ice, dinotefuran in boiled rice was extracted well. A measurement method comprising sample preparation (acetonitrile extraction, gel permeation chromatography, and SPE) and detection with anLC–MS/MS system was used. In 10 out of 25 commercial brown rice samples, dinotefuran was detected at a concentration of 0.04 μg/g (mean), which was more than the limit of quantitation of 0.01 μg/g. The dinotefuran levels were significantly less than the MRL of 2 μg/g in Japan. Even after polishing, washing, and boiling, dinotefuran was detected in 10 brown rice samples, with mean residue levels of 74.7%, 60.8%, and 39.6%, respectively, of the original concentration in brown rice. Based on these data, the processing factor of dinotefuran in boiled rice has been estimated to be approximately 0.4. Dinotefuran residues were reduced in the boiled rice, but less so than other pesticides. Although the maximum daily intake of dinotefuran in boiled rice was 0.0065 mg/person/day, its percent ratio to the ADI of dinotefuran in Japan was less than 0.05%. These results suggest that the daily intake of dinotefuran from rice might not be a critical problem at present, in spite of its relatively high detection frequency in boiled rice.

Persistent organic pollutants (POPs) in fresh water farm fish species from Punjab (India) and evaluation of their dietary intake for human risk assessment

ABSTRACTIn India, persistent organic pollutants (POPs) have been used extensively in both agricultural and industrial sectors, resulting in deterioration of terrestrial and aquatic environment. In the present study, analysis of POPs in fresh water ecosystem comprising samples of fish, sediments, and water was done from fish farms in Punjab, India. POP residues comprising lindane, p,p’-DDE, p,p’-DDD, endosulfan sulfate, and polychlorinated biphenyl (PCB) congeners (PCB-28, PCB-138, PCB-180) were detected in fish samples. Residues of p,p’ DDE and p,p’ DDD were recorded utmost in fish flesh with mean levels of 13.8 and 5.8 ng g−1, respectively. PCB residues were estimated in 20 fish samples with values in the range ND–46.3 ng g−1. The mean residue levels detected in this study were lower than the recommended maximum residue limits (MRLs) described by EU-MRLs, Italian-MRLs, FDA-2001, and FAO-1983. At the current levels of POP residues in fish flesh, the human health risk assessment based on both deterministic (mean residue levels) and probabilistic (95th percentile upper bound limit) approaches, reflected that cancer and non-cancer risks were within United States Environmental Protection Agency (USEPA) prescribed limits. The presence of POP residues in fish farm sediments and water elucidated the relationship between occurrence of POP residues in fish and its aquatic environment.

Persistent Organochlorine Contaminant Residues in Tissues of Hedgehogs from Turkey.

The residues of persistent organochlorinated pollutants (POPs), namely polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) (HCHs, CHLs, HCCPs, DDTs, and dicofol congeners) were investigated in the hair and muscle of road-killed Erinaceus roumanicus and E. concolor in Turkey. Mean residue levels were as follows: in hair, PCBs = 7.43 ± 4.88ng/g and OCPs = 9.21 ± 1.27ng/g; in muscle, PCBs = 30.73 ± 2.51ng/g and OCPs = 145.04 ± 16.59ng/g. There was no significant difference between species and sex, while there was significant difference between habitats and regions in terms of either total PCB and OCP levels, or POP levels (p < 0.05). Age was a determinative factor for the bio-accumulation of POPs. The contaminant levels were high in the species, sample areas, and habitats. The data also showed that tissues of hedgehogs are suitable for monitoring and evaluating the bioaccumulation of POP levels in Turkey.

A study on residue levels of fungicides and insecticides applied according to the program of raspberry protection

This paper presents surveys on residue levels of fungicides and insecticides applied according to the raspberry protection program. The field trials were conducted in 2013–2014 on a plantation of raspberry of the Laszka variety dessert raspberry very popular in Poland. Laboratory samples were collected starting from a day of the first fruit picking to the end of harvest. The highest mean residue levels were found for boscalid and pyraclostrobin (2.395 mg/kg and 0.732 mg/kg, respectively), in both cases they were at a level of about 24% of their maximum residue levels (MRLs); and for cypermethrin (0.235 mg/kg; i.e. close to 50% of its MRL). The long-term dietary intakes of those substances by Polish adult consumers were also at low levels of 0.52, 0.22, and 0.04% of acceptable daily intake (ADI), respectively. Therefore, the results obtained indicated that even on day zero of picking ripe raspberries, the pesticide residues not only were well below their corresponding MRLs, but also their daily intakes did not even approach 1% of the ADI. In 2013, pesticide residues in ripe fruit evolved according to a pattern different than in a subsequent year; while in 2014 they changed at a constant exponential rate.

Variability of pesticide residues in eggplant units collected from a field trial and marketplaces in Greece

Variability of pesticide residues among food items is very important when assessing the risks and food safety for the consumers. Therefore, the present study was undertaken to estimate the unit-to-unit residue variability factors for eggplant. In total, 120 samples from a trial field and 142 samples from different marketplaces in Thessaloniki, Greece, were collected to estimate the variability of pesticide residues in eggplant units. They were extracted by the QuEChERS method and the residues were determined by LC-MS/MS. For the field samples, the unit-to-unit variability factors (VFs) obtained for cypermethrin and deltamethrin residues were 2.54 and 2.51, respectively. The mean residue levels of both pesticides were higher in the composite samples than in the individual samples. The average VFs for the marketplace samples was 3.89. The eggplant units exposed to pesticides were higher in residues than the non-exposed units. The variability factors obtained in the marketplace samples were higher than those in the samples collected from the field trial. A default VF value of 3 for field trials is appropriate for use when assessing the acute dietary intake but a VF for the marketplace samples should be reconsidered with a larger data. © 2017 Society of Chemical Industry.

Food Processing Effect on the Residue Levels of Organochlorine Compounds In Fishes

A study was conducted to screen certain pesticide residues such as Organochlorine compounds in fish samples and to assess the effect of food processing methods on degradation of residue levels in both natural and spiked samples. Fish samples were collected from local areas of Hyderabad, Telangana, India and subjected to various food processing such as boiling and broiling and samples were analyzed by using Gas Chromatography- Electron Capture Detector by employing QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method for sample extraction and cleanup process. The final mean residual levels and their degradation percentage was also calculated with respective treatments. Heat processing methods proved to be highly effective on degradation of some Organochlorine compounds in both natural and spiked samples of fishes. Both the treatments i.e. boiling and broiling were statistically nonsignificant on degradation of respective pesticides in both natural and spiked samples of fishes.

Residual Stress, Microstructure and Hardness of Thin-Walled Low-Carbon Steel Pipes Welded Manually

The aim of this work is to evaluate the welding residual stress profile in ASTM A106 Gr. B steel pipes with 4 diameter and to correlate this profile with the microstructure and hardness of the joint. The results showed that the residual stresses are more uniform for a lower welding heat input. Higher welding heat input causes not only a non-uniformity of the stress profile but also promotes the maximum stress as high as the yield strength. The microstructure was composed of ferrite, perlite and possibly bainite; the presence of martensite was not verified. The hardness results indicated that none of the welding parameters used produced levels of hardness greater than 249 HV. Such a result is of fundamental importance because it suggests that low hardness does not necessarily mean low residual stress levels.