Furan Analysis Research Articles

Multi-parameter-based fuzzy logic diagnostic system for health assessment of power transformer

ABSTRACT Power transformers are the most valuable assets in the power system. An appropriate asset management is therefore essential for ensuring a reliable power supply to the utility managers. This is accomplished through continuous transformer condition monitoring. The transformers’ asset management involves a severe investigation into its insulation health index. It is determined by utilising several diagnostic parameters of transformer insulation. In this context, a novel fuzzy logic-based health index model has been proposed in the present paper to find the overall health condition of transformers. This model utilises the results extracted from several important diagnostic tests of transformer insulation, such as furan analysis and dissolved gas analysis. The validity of the proposed fuzzy logic model has been tested using real data from 200 transformer samples. These samples are collected from different-rated transformers of the Himachal Pradesh State Electricity Board (HPSEB), India. Further, the efficacy of the proposed fuzzy logic model has been validated against the expert model presented in literature. It is revealed from the comparison that the accuracy of the present proposed model is 92%. Also, it is observed that the proposed fuzzy logic model is very effective in interpreting dissolved gases and the other diagnostic test results of the transformer.

Validation of putative biomarkers of furan exposure through quantitative analysis of furan metabolites in urine of F344 rats exposed to stable isotope labeled furan

Humans are chronically exposed to furan, a potent liver toxicant and carcinogen that occurs in a variety of heat-processed foods. Assessment of human exposure based on the furan content in foods is, however, subject to some uncertainty due to the high volatility of furan. Biomarker monitoring is thus considered an alternative or complementary approach to furan exposure assessment. Previous work suggested that urinary furan metabolites derived from the reaction of cis-2-butene-1,4-dial (BDA), the reactive intermediate of furan, with glutathione (GSH) or amino acids may serve as potential biomarkers of furan exposure. However, some metabolites were also reported to occur in urine of untreated animals, indicating either background contamination via animal feed or endogenous sources, which may limit their suitability as biomarkers of exposure. The overall aim of the present study was to accurately establish the correlation between external dose and concentration of furan metabolites in urine over time and to discriminate against endogenous formation and furan intake via feed. To this end, the furan metabolites GSH-BDA (N-[4-carboxy-4-(3-mercapto-1H-pyrrol-1-yl)-1-oxobutyl]-L-cysteinylglycine), NAcLys-BDA (R-2-(acetylamino)-6-(2,5-dihydro-2-oxo-1H-pyrrol-1-yl)-1-hexanoic acid), NAcCys-BDA-NAcLys (N-acetyl-S-[1-[5-(acetylamino)-5-carboxypentyl]-1H-pyrrol-3-yl]-L-cysteine) and NAcCys-BDA-NAcLys sulfoxide (N-acetyl-S-[1-[5-(acetylamino)-5-carboxypentyl]-1H-pyrrol-3-yl]-L-cysteine sulfoxide) were simultaneously analyzed by stable isotope dilution ESI–LC–MS/MS as unlabeled and [13C4]-furan dependent metabolites following oral administration of a single oral dose of isotopically labelled [13C4]-furan (0.1, 1, 10, 100 and 1000 µg/kg bw) to male and female F344/DuCrl rats. Although a linear correlation between urinary excretion of [13C4]-furan-dependent metabolites was observed, analysis of unlabeled NAcLys-BDA, NAcCys-BDA-NAcLys and NAcCys-BDA-NAcLys sulfoxide revealed substantial, fairly constant urinary background levels throughout the course of the study. Analysis of furan in animal feed excluded feed as a source for these background levels. GSH-BDA was identified as the only furan metabolite without background occurrence, suggesting that it may present a specific biomarker to monitor external furan exposure. Studies in humans are now needed to establish if analysis of urinary GSH-BDA may provide reliable exposure estimates.

Analysis of Furan and Its Derivatives in Food Matrices Using Solid Phase Extraction Coupled with Gas Chromatography-Tandem Mass Spectrometry.

The objective of this study was to develop a simultaneous analysis method of furan and its 10 derivatives in different food commodities. The results indicated that furan and its 10 derivatives could be separated within 9.5 min by using a HP-5MS column and gas chromatography-tandem mass spectrometry (GC-MS/MS) with multiple reaction monitoring mode for detection. Furthermore, this method could resolve several furan isomers, such as 2-methyl furan and 3-methyl furan, as well as 2,3-dimethyl furan and 2,5-dimethyl furan. The most optimal extraction conditions were: 5 g of the fruit or juice sample mixed with 5 mL of the saturated NaCl solution, separately, or 1 g of the canned oily fish sample mixed with 9 mL of the saturated NaCl solution, followed by the equilibration of each sample at 35 °C for 15 min, using a carboxen-polydimethylsiloxane SPME arrow to adsorb the analytes for 15 min at 35 °C for subsequent analysis by GC-MS/MS. For method validation of all the analytes in the different food matrices, the recovery was 76-117% and the limit of the quantitation was 0.003-0.675 ng/g, while the relative standard deviation (RSD%) of the intra-day variability range from 1-16%, and that of the inter-day variability was from 4-20%. The method validation data further demonstrated that a reliable method was established for the analysis of furan and its 10 derivatives in commercial foods.

Feasibility Test of Transformer Insulating Oil Lifetime Based on Breakdown Voltage (bdv) and Furan Analysis

Optimization of transformer performance in distributing electrical energy is determining by transformer insulating oilquality. Insulating oil temperature increases with the great of transformer workload released during the distributionof electric power to consumers. Then, it will be affected to the breakdown voltage (BDV) value and oil quality whichcan even lead to the insulating oil failure. This research is carried out by taking a sampling of new deck oil and usedoil at different temperatures. Then insulating oil is tested by using BDV test and Dissolved Gas Analysis (DGA) todetermining furan value and workability of insulating oil lifetime. Thus, this research expected to identify the feasibilityof transformer insulating oil lifetime based on breakdown voltage and furan value.

Methodical peculiarities of air sampling for detecting contents of low molecular weight organic compounds on the example of furan and methylfuran

Introduction. Variable analytical control methodologies are applied in monitoring over contents of low molecular weight organic compounds in ambient air. Their unification is a vital and serious challenge requiring valid substantiation and selection of optimal air sampling techniques. Our research goal was to substantiate and select an air sampling technique for chemical analysis of furan and methylfuran. Materials and methods. Our research concentrated on developing and optimizing the process of air samples preparation for chemical analysis of furan and methylfuran; examining effectiveness of furan and methylfuran sorption-desorption using various sorbents. Standard furan and methylfuran samples (≥99.0% Sigma-Aldrich), heptane solvents, sorbent tubes with Tenax, Sylochrom C-120, and coal as sorbents were used in the research. All experimental studies were aimed at testing effective procedures for taking and preparing air samples for further furan and methylfuran analysis in them. They were performed on “Kristall-5000” gas chromatographer with mass-selective detection (MSD) and 25-meter long PoraPlotQ-capillary column. Results. We comparatively analyzed the results produced by taking air samples for further detection of furan and methylfuran in them using different techniques. They included low temperature concentration; sorption on filters made of quartz microfiber and a sorbent tube with Nenax TA; sorption on a tube with Tenax TA at t=20-25 °C. The analysis enabled us to reveal an effective procedure for taking ambient air samples for further detection of furan and methylfuran in them. This procedure was low temperature concentration of low molecular weight organic compounds on a sorbent tube with Tenax TA. Limitations. The accomplished study had no limitations. Conclusion. The accomplished study allows us to recommend taking air samples during 10 minutes with consumption being 0.1 l/min for further detection of furan and methylfuran in them using low temperature concentration on a sorbent tube with Tenax TA. The achieved effectiveness is 99.2% for furan and 100% for methylfuran.

Analysis of Furan in Red Pepper Powder Treated by Three Methods-Boiling, Roasting, and Frying.

In this study, furan analysis was conducted on dried red pepper powder treated by three cooking methods (boiling, roasting, and frying). A total of 144 samples were prepared and their furan levels were analysed using automated solid-phase micro-extraction gas chromatography-mass spectrometry. The furan concentration in boiled soup ranged from 1.26 to 4.65 ng/g, and from 7.37 to 27.68 ng/g for boiled red pepper samples. For the roasting method, a furan concentration between 6.66 and 761.37 ng/g was detected. For the frying method, the furan level of edible oils ranged from 3.93 to 125.88 ng/g, and a concentration ranging from 4.88 to 234.52 ng/g was detected for the fried red pepper samples. The cooking method using edible oil obtained a higher furan concentration than the water-based method. Samples using corn germ oil (linoleic acid-rich oil) obtained the highest furan concentration among the four edible oils. In all cooking methods, the higher the heating temperature and time, the higher the furan concentration detected. A kinetic study was conducted using the roasting model system and the apparent activation energy was 60.5 kJ/mol. The results of this study could be useful as a database for furan concentration in dried red pepper powder according to various cooking methods.

Analysis of furan and its major furan derivatives in coffee products on the Chinese market using HS-GC–MS and the estimated exposure of the Chinese population

The current study analysed concentrations of furan and its derivatives in coffee products commercially available in China based on an improved headspace gas chromatography-mass spectrometry (HS-GC–MS) method and estimated health risks. A total of 101 samples of coffee products on the Chinese market was analysed. Furan (98%, ND-6569 μg/kg) and 2-methylfuran (100%, 2–29639 μg/kg) were the compounds with the highest concentrations and detection rates in coffee products. The mean dietary exposure of Chinese consumers to furan and the sum of furan, 2-methylfuran and 3-methylfuran in coffee products was 0.09 and 0.46 μg/kg bw/day, respectively. For the neoplastic effects of furan, the margin of exposure (MOE) was 14,556 for the mean dietary exposure of consumers. For the non-neoplastic effects of furan, MOEs were 711 and 139 for furan and the sum of furan, 2-methylfuran and 3-methylfuran, respectively. Overall, a health concern is indicated for coffee consumers with MOEs below 10000.

Smart Techniques for Fault Diagnosis in Power Transformer

In a power network installed transformers are among the most expensive equipment. Outage of a transformer causes substantial financial loss not only due to the cost involved in repair or replacement, but also due to loss of revenue until corrective action is taken. To avoid the financial and reliability loss in the past two decades the monitoring of in-service transformer health has become obligatory for the utilities. The tests that were earlier done were to assess the dame of permanent nature. However, it has been known for quite some time that system abnormalities, switching. Loading, ambient conditions contribute to accelerated aging that results in sudden failure or incipient faults. Monitoring the condition of in-service equipment can always reduce failure risk. For early detection of fault dissolved gas analysis, furan analysis and degree of polymerization are the recent techniques that are becoming prevalent. A real-time assessment of the transformer condition using these techniques is an important tool for enhancing system reliability.

Effects of the Frying and Drying Conditions on the Furan Formation in Instant-Noodle Manufacturing.

In this study, furan analysis was conducted in instant fried and dried noodles manufactured under various frying and drying conditions, respectively. Instant fried noodles were manufactured via five different frying durations (30-150 s). The levels of furan formed in the fried noodles during the manufacturing process ranged from 4.26 to 41.8 ng/g. The instant dried noodles were manufactured at four different temperatures (80-130 °C). The levels of furan formed in the dried noodles ranged from 3.99 to 4.11 ng/g. The black-bean paste, which is the main ingredient of the black-bean sauce, had the highest furan level (16.5-2484 ng/g) in instant noodles. Our results showed that the furan formation increased with the frying temperature and duration of the black-bean paste (p < 0.05). The activation energy (Ea) in the black-bean paste was estimated at 58.627 kJ/mol by using the Arrhenius formula. The calculated Ea was similar to the Ea of the general chemical reaction. The results of this study might be useful to minimize the furan formation in the manufacture of instant noodles.

Study of Parameters Affecting the Aging of Transformer Oil

An electricity board acquires several transformers from a manufacturer in a belief that their advertised lifetime of the transformer thus purchased is true. However, they don’t take in the case of negligence in maintenance of transformer, which is a strenuous job. The advertised thirty-year lifetime is reduced to a mere two-year lifetime, mainly because of the degradation of the insulation medium (Transformer oil), thus increasing losses in the transformer and decreasing its efficiency. The degradation of transformer oil leads to safety hazards like transformer bursting, consequently forcing the electricity board to replace the transformer, thus incurring huge amount of costs. This is the most relatable problem faced by the electricity board in every state. This research work aims at listing out various properties of transformer oil and ascertaining major impurities in a transformer oil by testing it using various techniques. The proposed work deals with long term observation and analysis of transformer oil to determine its degradation rate. Breakdown voltage, Moisture content, Resistivity, Acidity, Furan Analysis and Dissolved Gas Analysis were done using Mushroom electrodes, Karl Fischer Titration test, Tan delta test, Potassium Hydroxide Titration, High performance liquid chromatography, and dissolved gas analyzer respectively. The results reveal that, deviation of Breakdown Voltage, Moisture content, and 2-Furaldehyde (1197ppb) from the permissible limits can indicate the aging of the transformer.

22.9kV 유입변압기 절연지 열화생성물 분석을 통한 사용연수 상관관계 분석

To prevent accidents through maintenance and appropriate replacement of oil-immersed transformer, the correlation between the life-time of the transformer was estimated by comparing the furan analysis of the insulation paper according to the accelerated deterioration and the insulating oil. According to accelerated deterioration, the furan value of DDP was reduced to about 1/1000 compared to that of Kraft paper, and it was shown that the thermal properties were excellent by the epoxy coating. As a result of the analysis of the degree of polymerization of the insulating paper, when the furan value was about 200 ppb, it was determined that the paper performance was lowered. Although the number of transformers collected is small, the life-time of the oil-immersed transformer is about 37 years.

Assessment of Transformer Cellulose Insulation Life Expectancy Based on Oil Furan Analysis (Case Study: South African Transformers)

Assessment of Transformer Cellulose Insulation Life Expectancy Based on Oil Furan Analysis (Case Study: South African Transformers)

Determination of furan in canned foods and packaged beverages by headspace gas chromatography-mass spectrometry

A headspace gas chromatography-mass spectrometry(HS-GC-MS) method for the analysis of furan in canned foods and packaged beverages was established. The furan was extracted from the samples by headspace method. D_4-furan was used as internal standard and separated on a HP-Plot Q(30 m×0.32 mm, 20 μm) column. The results were qualitative and quantitative by gas chromatography-mass spectrometry. The linear range of this method was 2.0-200.0 ng, and the regression equation of the working curve was y=1.14x +0.116(r~2=0.999). The recoveries were 86.3%-96.2% with the relative standard deviations(RSDs) less than 10%(n=6). The limit of quantification of furan was 1.0 ng. Through the detection of 59 samples, it was found that the common canned food and hard packaged drinks were commonly contaminated with furan, and the concentration of furan in coffee, milk tea, canned fish and other products were relatively high, with a maximum value of 153.99 ng. The method is simple, rapid, accurate and reliable, and could be used for the detection of furan in the two kinds of food.

Formation of furan in baby food products: Identification and technical challenges

Furan is generally produced during thermal processing of various foods including baked, fried, and roasted food items such as cereal products, coffee, canned, and jarred prepared foods as well as in baby foods. Furan is a toxic and carcinogenic compound to humans and may be a vital hazard to infants and babies. Furan could be formed in foods through thermal degradation of carbohydrates, dissociation of amino acids, and oxidation of polyunsaturated fatty acids. The detection of furan in food products is difficult due to its high volatility and low molecular weight. Headspace solid-phase microextraction coupled with gas chromatography/mass spectrometer (GC/MS) is generally used for analysis of furan in food samples. The risk assessment of furan can be characterized using margin of exposure approach (MOE). Conventional strategies including cooking in open vessels, reheating of commercially processed foods with stirring, and physical removal using vacuum treatment have remained unsuccessful for the removal of furan due to the complex production mechanisms and possible precursors of furan. The innovative food-processing technologies such as high-pressure processing (HPP), high-pressure thermal sterilization (HPTS), and Ohmic heating have been adapted for the reduction of furan levels in baby foods. But in recent years, only HPP has gained interest due to successful reduction of furan because of its nonthermal mechanism. HPP-treated baby food products are commercially available from different food companies. This review summarizes the mechanism involved in the formation of furan in foods, its toxicity, and identification in infant foods and presents a solution for limiting its formation, occurrence, and retention using novel strategies.

Analysis of furan in various instant noodles by solid-phase microextraction–gas chromatography/mass spectrometry

In this study, 158 samples of instant noodles were analysed according to the sauce (soup, black soybean sauce, spicy sauce), packaging (bag, bowl) and recipe (original, modified) for furan quantification by automated solid-phase microextraction–gas chromatography/mass spectrometry. The concentration range of furan in raw and cooked noodles was 4.24–13.2 and 1.71–8.14 ng/g, respectively. Among the sauces, black soybean sauce has the highest furan levels of 27.0–218 (raw) and 8.47–126 (cooked) ng/g. After cooking, the furan content decreased by 37.7% (noodles), 86.2% (soup base), 89.1% (black soybean sauce) and 82.8% (spicy sauce). The reduction rate of furan in the sauce was more than two-fold higher than that in noodles. The results obtained in this study are considered useful as a database for analysis of furan in instant noodles.

Optimization and Validation of HS-SPME-GC-MS for the Determination of Furan and Alkylfurans in Chocolate-Based Products: Impact of Tempering and Laser Printing.

Furan and its alkyl substituted (2-methylfuran, 3-methylfuran, 2,3-dimethylfuran, 2,5-dimethylfuran) are found in a range between ppm to sub-ppb levels in many foodstuffs undergoing heat treatments like coffee, chicory, or even chocolate. Two major objectives are presented. First, we aim at optimizing and validating a HS-SPME-GC-MS method for the quantification of five alkylfurans in chocolate. Second, we focus our study on measuring the quantitative impact of engraving technique on the formation of furan and its derivatives in chocolate, from the raw callets to processed end-products. HS-SPME-GC-MS method operating in SIM mode and using isotope dilution technique with deuterated homologue internal standards was used to quantify alkylfurans in chocolate. Good repeatability (RSD% = 0.1-8%, in duplicate) and intermediate precision (RSD% = 1.7-7%, n = 6) were obtained for these five process contaminants at 10, 25, and 50 µg/kg. Trueness was varying between 81 and 109%. LoQ ranged from 0.48 to 2.50 µg/kg. Relative expanded measurement uncertainties ranged from 6 to 30%. Finally, tempering is responsible for a 24% increase in furan contamination, while the laser engraving technique results in an additional 31% increase in furan. A similar trend was also observed for 2-methylfuran and 3-methylfuran, whereas no significant increases were observed for 2,3-dimethylfuran and 2,5-dimethylfuran. A reliable and sensitive method of HS-SPME-GC-MS was reported for the first time for the analysis of furan and four alkylfurans in chocolate. This paper demonstrated that engraving using laser-based techniques can increase the levels of these compounds by up to 30%.

Biomonitoring of heat-induced food contaminants: Quantitative analysis of furan dependent glutathione- and lysine-adducts in rat urine as putative biomarkers of exposure

Furan is a liver toxicant and carcinogen that occurs in heat-processed foods. Due to its volatility, analysis of furan in food does not provide reliable estimates of exposure. Biomarker-based approaches offer the opportunity to more accurately assess human exposure, but a correlation between concentrations of potential biomarkers of furan exposure and external dose has not been established.Bioactivation of furan and subsequent reaction of cis-2-butene-1,4-dial (BDA) with cellular nucleophiles gives rise to a range of metabolites that may serve as biomarkers of furan exposure. In this study, N-[4-carboxy-4-(3-mercapto-1H-pyrrol-1-yl)-1-oxobutyl]-L-cysteinylglycine cyclic sulfide, a mono-glutathione adduct of BDA (GSH-BDA), and R-2-acetylamino-6-(2,5-dihydro-2-oxo-1H-pyrrol-1-yl)-1-hexanoic acid, an adduct of BDA with Nα-acetyl-L-lysine (NAcLys-BDA), were synthesized and analysed by LC-MS/MS in urine of rats treated with furan at 0, 0.1, 0.5 and 2.0 mg/kg bw for 5 and 28 days.GSH-BDA and NAcLys-BDA were both excreted in a dose-related manner. 24 h excretion rates ranged between 0.6 and 1.1% of the administered dose for GSH-BDA, and 1.4–2.1% for NAcLys-BDA. In contrast to GSH-BDA, NAcLys-BDA was also present in urine of controls, suggesting either endogenous formation or background exposure.Overall, the close correlation between urinary furan metabolites and external dose provides experimental support for biomarker-based approaches to monitor human exposure to furan.

Analysis of furan and monosaccharides in various coffee beans.

The furan levels in commercial coffee product samples (17 instant coffees, 12 mixed coffee, 8 canned coffee) were 49-2155, 10-201 and 15-209ng/g, respectively. Since thermal degradation/rearrangement of carbohydrates is the main source of furan, the concentrations of furan and monosaccharides (mannose, rhamnose, glucose, galactose and arabinose) were analysed in 26 green and roasted coffee bean (Coffea arabica) varieties. In coffee beans, furan levels ranged from 4.71 (Bourbon Cerrado, Brazil) to 8.63mg/kg (San Vicente, Honduras). Galactose was the main monosaccharide in green beans, followed by arabinose, glucose, mannose and rhamnose, on average. Roasting decreased the glucose content by about 81%, and arabinose decreased about 27% in all coffee beans. Glucose decreased the greatest after roasting and is thereby considered the major contributor to the formation of furan.

Analysis of furan in semi-solid and paste type foods.

An analytical method for furan in semi-solid and paste-type food products that have been widely used consumed in Korea was presented using headspace solid-phase microextraction by gas chromatography-mass spectrometry. Total 131 food samples were analyzed and categorized into 11 groups. The validation parameters such as linearity, limit of detection (LOD), limit of quantitation (LOQ), precision (RSD) and accuracy were verified. The linearity with regression coefficients was obtained from 0.9962 to 0.9996 and the values of LOD and LOQ were 0.18ng/g and 0.54ng/g, respectively. The recoveries were obtained from 88.03 to 105.06%. The analysis of furan in such matrix was qualified and quantified by using the developed validation method. Dry cereals, pickled cucumbers, and oyster sauces contained high furan contents with average values 8.60, 6.45, and 4.40ng/g, respectively.

Evaluation of multiple alternative instrument platforms for targeted and non-targeted dioxin and furan analysis.

The use of gas chromatography coupled to high-resolution magnetic sector mass spectrometers (GC-HRMS) is well established for dioxin and furan analysis. However, the use of gas chromatography coupled to triple quadrupole (MS/MS) and time of flight (TOF) mass spectrometers with atmospheric pressure ionization (API) and traditional electron ionization (EI) for dioxin and furan analysis is emerging as a viable alternative to GC-HRMS screening. These instruments offer greater versatility in the lab for a wider range of compound identification and quantification as well as improved ease of operation. The instruments utilized in this study included 2 API-MS/MS, 1 traditional EI-MS/MS, an API-quadrupole time of flight mass spectrometer (API-QTOF), and a EI-high-resolution TOF (EI-HRTOF). This study compared these 5 instruments to a GC-HRMS using method detection limit (MDLs) samples for dioxin and furan analysis. Each instrument demonstrated acceptable MDL values for the 17 chlorinated dioxin and furans studied. The API-MS/MS instruments provide the greatest overall improvement in MDL value over the GC-HRMS with a 1.5 to 2-fold improvement. The API-QTOF and EI-TOF demonstrate slight increases in MDL value as compared with the GC-HRMS with a 1.5-fold increase. The 5 instruments studied all demonstrate acceptable MDL values with no MDL for a single congener greater than 5 times that for the GC-HRMS. All 5 instruments offer a viable alternative to GC-HRMS for the analysis of dioxins and furans and should be considered when developing new validated methodologies.