Evaluation of carbonyl species in fish oil: An improved LC–MS/MS method

Fish oil, a common source of omega-3 fatty acids, can be easily oxidized to generate carbonyl species, thus, the measurement of these compounds in fish oil are significant for food safety. Here, a comprehensive and sensitive method to quantify forty-four carbonyl species including toxic substances such as acrolein, glyoxal, methylglyoxal and trans-4-hydroxy-2-hexenal in fish oil has been developed and validated. The samples were derivatized with 2,4-dinitrophenylhydrazine, cleaned using C18 solid phase extraction, and analyzed by liquid chromatography coupled with tandem mass spectrometry. The calibration curves represented satisfactory linearity (r² > 0.998) and the quality control samples showed favorable precisions within an acceptable range (RSD < 10%). The accuracies ranged from 96 to 109%. The detection and quantification limits ranged from 1.5 to 30 ng/mL and 5–90 ng/mL, respectively. The method was successfully applied to determine carbonyl species in ten fish oil products. The proposed method is suitable for high throughput analysis of carbonyl species in fish oil.     

Validation of an ultra high performance liquid chromatography–tandem mass spectrometry method for detection and quantitation of 19 endocrine disruptors in milk

An endocrine disruptor (ED) is an exogenous compound that interferes with the body's endocrine system. Exposure to EDs may result in adverse health effects such as infertility and cancer. EDs are composed of a vast group of chemicals including compounds of natural origin such as phytoestrogens or mycotoxins and a wide range of man-made chemicals such as pesticides. Synthetic compounds may find their way into the food chain where a number of them can biomagnify. Additionally, processing activities and food contact materials may add further to the already existing pool of food contaminants. Thus, our diet is considered to be one of the main exposure routes to EDs. Some precautionary legislation has already been introduced to control production and/or application of some persistent organic pollutants with ED characteristics. However, newly emerging EDs with bioaccumulative properties have recently been reported to appear at lower tiers of the food chain but have not been monitored at the grander scale.Milk and dairy products are a major component of our diet, thus it is important to monitor them for EDs. However, most methods developed to date are devoted to one group of compounds at a time. The UHPLC–MS/MS method described here has been validated according to EC decision 2002/657/EC and allows simultaneous extraction, detection, quantitation and confirmation of 19 EDs in milk. The method calibration range is between 0.50 and 20.0 μg kg⁻¹ with coefficients of determination above 0.99 for all analytes. Precision varied from 4.7% to 23.4% in repeatability and reproducibility studies. Established CCα and CCβ values (0.11–0.67 μg kg⁻¹) facilitate fast, reliable, quantitative and confirmatory analysis of sub μg kg⁻¹ levels of a range of EDs in milk.     

Development and evaluation of two ELISA formats for the detection of β-lactoglobulin in model processed and commercial foods

Milk proteins have many functional properties, making them valuable food ingredients. However, they are a frequent cause of food allergy, especially in children. The aim of the present work was to develop and evaluate two immunoassays (indirect competitive and double antibody sandwich formats) for the detection of undeclared milk proteins in foods. Antisera raised to β-lactoglobulin was used in the competitive assay and antibodies isolated by immunoadsorption in the sandwich ELISA. Results obtained indicated that the sandwich format could detect lower percentages of powdered milk added to processed model foods than the competitive format. Likewise, the sandwich assay could discriminate better than the competitive assay between commercial foods with declared or non-milk ingredients. The antibody population used to recognize the target protein as well as the particularities of each ELISA format greatly influence the determination of immunoreactive β-lactoglobulin present in processed food.     

Phenotypic and genotypic characteristics of Listeria monocytogenes strains isolated during 2011–2014 from different food matrices in Switzerland

One hundred and forty two Listeria monocytogenes strains isolated from different food matrices in Switzerland between 2011 and 2014 were characterized with respect to their genotypic and phenotypic properties. Analyzed strains originated from various meat, milk, plant-associated food products and production environments as well as from other types of foods including fish, seafood, and ready to eat (RTE) products. The collection included serotype 1/2a (64%), 4b (15%), 1/2c (12%), 1/2b (7%) and 3c (3%). The strains were genetically diverse representing 61 MLST sequence types (ST) including 24 new STs. The most frequent clonal complexes (CC) were CC9 (15%) and CC121 (12%). PCR screening detected presence of the stress survival islet (SSI-1) in 50% of the strains. Phenotypic resistance to benzalkonium chloride (BC) was detected in 18% of the strains. The BC resistance genetic determinants qacH and bcrABC were detected in 80% and 12% of the strains, respectively. Most (n = 129) of the strains isolated from Swiss food matrices exhibited poor biofilm formation capacity and there were no correlations detected between strain serotypes, genotypes and biofilm production.     

Rapid approach for the determination of alcoholic strength and overall quality check of various spirit drinks and wines using GC–MS

In this study, we have developed a simple, high throughput method applicable for determination of alcoholic strength by volume in spirit drinks and wines, only small sample volume (50 μl) is required for the analysis. Gas chromatography (GC) coupled to mass spectrometry (MS) is employed for this purpose. While split sample injection is used in analysis of most spirits, headspace solid–phase sampling of volatiles by solid phase micro extraction (HS–SPME) has to be used for analysis of more complex samples such as egg liqueur or port wine. Quantification of ethanol is performed by isotopic dilution using 2,2,2-trideuterioethanol as an internal standard. The method validation was carried out on five various categories of distilled spirit drinks represented by vodka, whisky, pear brandy, grappa and rum (differing in a content of other commonly controlled volatiles such as acetaldehyde, methanol, ethyl acetate and fusel alcohols), three wines, port wine and egg liqueur. The repeatability of determined alcoholic strength expressed as a relative standard deviation ranged for tested samples from 0.19 to 0.98%, the trueness of results was successfully verified within the proficiency testing programme FAPAS^®. In addition, using this newly developed method, denaturants such as propan-2-ol, 2-methylpropan-2-ol and/or methanol can be screened.     

Screening for β-agonists in sheep urine and eyes by an enzyme-linked immunosorbent assay in the state of Kuwait

Data are reported here on the assessment of the potential use of an enzyme-linked immunosorbent assay (ELISA) to monitor the presence of the β-agonist, clenbuterol in 142 samples of sheep urine and 53 samples of eye tissues from the same sheep. Data obtained showed that the clenbuterol levels ranged in the urine and eye tissues from not detected to 0.272 ppb and not detected to 1.54 ppb tissue, respectively. For confirmation, all samples that showed to be ELISA positive for clenbuterol residues were analyzed by GC–MS and were all found to be negative.     

Use of GC-headspace and “electronic nose” for the detection of volatile compounds from glucose–glycine Maillard reaction

The present study deals with the use of headspace and gas sensor techniques for the measurements of Maillard volatiles in model system. Both methods can be used for assessing various processes in food control. The volatile compounds produced during thermal browning of glucose–glycine model system were collected by dynamic headspace techniques and analysed by GC–MS. The effect of added formaldehyde on the formation of the main constituents was measured at pH 4.5, 5.5 and 6.5. It was found that at pH 5.5 and 6.5 formaldehyde had a negative effect on the formation of the dominant components, furfural, 2-acetylfuran and 5-methylfurfural. The volatile compounds were also tested with an array of solid-state gas sensors. The effect of formaldehyde and acetaldehyde was analysed on the basis of the transient response signals generated by the aroma in the sensors. So-called τ-patterns were used to recognise the aroma from different model solutions as well as for pure compounds dominant in the aroma from the Maillard reaction.     

An Optimum Model for Speeding Exploration and Development-the Development Concept Design of the Carboniferous Reservoir in Datianchi Structural Belt in Sichuan Basin

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Hydroconversion of rapeseed oil to hydrocarbons in the presence of MFI/MCM-41 micro–mesoporous materials synthesized by the hydrothermal microwave method

Catalysts containing an MFI zeolite and an MFI/MCM-41 composite synthesized by the hydrothermal microwave method have been first studied in rapeseed oil hydroconversion. Catalysts provide the production of valuable petrochemicals, namely, high-octane components of motor fuels and С₂–С₄ olefins. Synthesized MFI zeolite mostly catalyzed the formation of aromatic hydrocarbons (ArH); incorporation of this zeolite into the matrix of mesoporous silicate MCM-41 leads to a decrease in the ArH content in the liquid hydrocarbon products owing to an increase in the yield of liquid aliphatic hydrocarbons. Promotion of the MFI zeolite synthesized by the hydrothermal microwave method with zinc ions leads to the formation of a catalyst providing the formation of liquid products consisting of ArH.     

Screening and confirmatory methods for the determination of melamine in cow’s milk and milk-based powdered infant formula: Validation and proficiency-tests of ELISA,HPLC-UV,GC-MS and LC-MS/MS

In recent years, two adulteration incidents concerning the addition of melamine, a small polar compound which is very rich in nitrogen, to pet food and infant formula products have occurred in China. These issues prompted private as well as governmental laboratories to develop methods for the analysis of melamine and related compounds in a wide variety of food products and ingredients. The development of methods was focussed on both, screening and quantification purposes, ranging from highly sophisticated chromatographic-mass spectrometric techniques to immuno-selective assays. The present work describes two screening and two confirmatory methods dedicated to the determination of melamine in cow’s milk and milk-based powdered infant formula. Screening methods are enzyme-linked immunosorbent assay (ELISA) and liquid chromatography coupled to ultraviolet detection, while confirmatory methods are based on gas and liquid chromatography coupled mass spectrometry techniques. Performance and validation data of the four methods, and results obtained in the frame of internal and European proficiency-tests are shown.     

Origin and controlling factors of chlorite coatings—an example from the reservoir of T3x Group of the Baojie area, Sichuan Basin, China

The study of the chlorite coatings always attracts scholars in China and other countries because the chlorite coatings play an important role in the preservation of residual primary pores in sandstone reservoirs.At present,the study of the origin and the controlling factors is relatively few.The occurrence,time of formation,genesis,controlling factors,and the mechanism of chlorite coatings inhibiting quartz overgrowths were studied in detail with thin section and SEM analysis.Samples were from the sandstone reservoirs of the T3x Group in the Baojie area,the transitional zone from the middle to the south of Sichuan Basin.The results indicate that the chlorite coatings on the walls of the pore spaces are oriented perpendicular to grain surfaces in the form of isopachous(even-thickness) grain-coating,while the chlorite coatings at the contacts between adjacent detrital grains are arranged with a preferred orientation tangential to the surface of detrital grains.The chlorite coatings were formed in the eogenetic stage.They were formed by recrystallization of Fe-rich clay films during the syndepositional period,and chlorite cements would be recrystallized after the coatings’ formation.The formation of chlorite coatings was mainly controlled by the depositional environment,provenance conditions,and diagenetic environment.The presence of chlorite coatings could result in the preservation of primary pores in deeply buried sandstone reservoirs by effectively inhibiting quartz overgrowths and the development of compaction and pressure solution.     

Direct conversion of ethanol and fusel oils to alkane–aromatic hydrocarbons in the presence of a pilot Pd–Zn/TsVM catalyst

The conversion of ethanol and fusel oils to a С₃–С₁₂ alkane–aromatic fraction with high activity and selectivity in the presence of the Pd–Zn/TsVM pilot catalyst has been demonstrated. It has been shown that the ethanol conversion to alkanes and aromatic hydrocarbons in the presence of this catalyst proceeds by various routes to give ethylene and diethyl ether as intermediate products providing a 90–95% yield on the converted ethanol carbon basis for the target С₃–С₁₂ fraction containing up to 40% of branched alkanes.     

In situ Raman spectroscopic quantification of CH_4–CO_2 mixture: application to fluid inclusions hosted in quartz veins from the Longmaxi Formation shales in Sichuan Basin,southwestern China

We re-evaluate the Raman spectroscopic quantification of the molar ratio and pressure for CH_4–CO_2 mixtures. Firstly, the Raman quantification factors of CH_4 and CO_2 increase with rising pressure at room temperature, indicating that Raman quantification of CH_4/CO_2 molar ratio can be applied to those fluid inclusions(FIs) with high internal pressure(i.e., 15 MPa).Secondly, the v_1(CH_4) peak position shifts to lower wavenumber with increasing pressure at constant temperature, confirming that the v_1(CH_4) peak position can be used to calculate the fluid pressure. However, this method should be carefully calibrated before applying to FI analyses because large discrepancies exist among the reported v_1(CH_4)-P curves, especially in the highpressure range. These calibrations are applied to CH_4-rich FIs in quartz veins of the Silurian Longmaxi black shales in southern Sichuan Basin. The vapor phases of these FIs are mainly composed of CH_4 and minor CO_2,with CO_2 molar fractions from4.4% to 7.4%. The pressure of single-phase gas FI ranges from 103.65 to 128.35 MPa at room temperature, which is higher than previously reported. Thermodynamic calculations supported the presence of extremely high-pressure CH_4-saturated fluid(218.03–256.82 MPa at 200 °C), which may be responsible for the expulsion of CH_4 to adjacent reservoirs.     

Synthesis Gas Production by Partial Oxidation of Methane and Dry Reforming of Methane in the Presence of Novel Ni–Co/MFI Catalysts

Catalysts based on Ni, Co, and NiCo supported on MFI zeolites for the partial oxidation of methane and dry reforming of methane to synthesis gas have been synthesized and studied. The total metal content in the catalysts is 2 wt %. A commercial zeolite with a binder (alumina) and a binder-free zeolite synthesized by an accelerated microwave-assisted hydrothermal method are used as supports. The synthesis gas yield is 97% in the presence of Ni and NiCo catalysts supported on the MFI zeolite synthesized by the microwaveassisted hydrothermal method. The simultaneous presence of Ni and Co in the catalyst makes the sample resistant to coking during dry reforming of methane, whereas the Ni catalyst is characterized by the formation of a significant amount of carbon fibers.     

Recovery of precious metals from spent Mo–Co–Ni/Al2O3 catalyst in organic acid medium: Process optimization and kinetic studies

In present study, the leaching kinetics of the spent Mo–Co–Ni/Al₂O₃ catalyst was investigated in the presence of formic acid as an organic leaching agent. Firstly, the spent catalyst was roasted in different roasting temperature (200–700?°C) and time (15–240?min), the maximum metal extraction was achieved that at 500?°C with 90?min. Then, the leaching experiments were carried out to determine the influences of process parameters following; particle size, liquid/solid ratio, formic acid concentration, leaching temperature, leaching time and stirring speed. According to the experimental results, the highest dissolution rates of molybdenum (Mo, 75.82%), cobalt (Co, 96.81%), nickel (Ni, 93.44%) and aluminum (Al, 19.46%) were reached under optimum experimental conditions; particle size +75???30?µm; liquid/solid ratio 10?ml/g; formic acid concentration 0.6?M; leaching temperature 80?°C; leaching time 90?min and stirring speed 300 r/min. Moreover, the leaching kinetics clearly reveal that the leaching reaction is controlled by liquid film diffusion and that the activation energy values (E_a) of Co, Ni, Mo and Al were to be 24.49, 25.98, 32.36 and 33.47?kJ/mol, respectively. In conclusion, the leaching process can be conducted in the presence of formic acid for the various industrial wastes in similar structure and composition to Mo–Co–Ni/Al₂O₃ spent catalyst.     

A compositional model for CO2 flooding including CO2 equilibria between water and oil using the Peng–Robinson equation of state with the Wong–Sandler mixing rule

This paper presents a three-dimensional, three-phase compositional model considering CO₂ phase equilibrium between water and oil. In this model, CO₂ is mutually soluble in aqueous and hydrocarbon phases, while other components, except water, exist in hydrocarbon phase. The Peng–Robinson (PR) equation of state and the Wong–Sandler mixing rule with non-random two-liquid parameters are used to calculate CO₂ fugacity in the aqueous phase. One-dimensional and three-dimensional CO₂ flooding examples show that a significant amount of injected CO₂ is dissolved in water. Our simulation shows 7% of injected CO₂ can be dissolved in the aqueous phase, which delays oil recovery by 4%. The gas rate predicted by the model is smaller than the conventional model as long as water is undersaturated by CO₂, which can be considered as “lost” in the aqueous phase. The model also predicts that the delayed oil can be recovered after the gas breakthrough, indicating that delayed oil is hard to recover in field applications. A three-dimensional example reveals that a highly stratified reservoir causes uneven displacement and serious CO₂ breakthrough. If mobility control measures like water alternating gas are undertaken, the solubility effects will be more pronounced than this example.     

Rapid determination of ergosterol in grape mashes for grape rot indication and further quality assessment by means of an industrial near infrared/visible (NIR/VIS) spectrometer – A feasibility study

Perceptual quality and food safety of grape products like wine is generally impaired by grape rot. Commonly applied visual inspection for quality assessment remains subjective. However, conventional analytical determinations are tedious and time-consuming. In contrast, near infrared/visible (NIR/VIS) spectroscopy is an objective and rapid alternative. An industrial spectrometer especially designed for on-line process integration was applied in laboratory configuration to evaluate the feasibility of the prediction of ergosterol and 12 further quality-associated parameters in grape mashes. Calibration models were established, validated, and evaluated. Spectral ranges used were 450–850 nm (VIS) and 1050–1650 nm (NIR). The regression method applied was partial least squares (PLS) regression. Calibrations at best suitable for discriminating low and high values were obtained for gluconic, acetic, tartaric, and titratable acids contents, pH value, ethanol content, and laccase activity. Therefore, for these parameters limits of NIR/VIS spectroscopy may be revealed. Calibrations for semi-quantitative predictions or rough estimations were obtained for fructose, glucose, and malic acid contents. Best performance suitable for quantitative predictions was achieved for relative density, glycerol, and ergosterol contents. The industrial spectrometer proved to perform similar to a research laboratory spectrometer. Consequently, a future on-line implementation of NIR/VIS spectrometers in wineries may be a valuable and reliable tool for rapid grape quality assessment at reception. Particularly, ergosterol content prediction proved to be a promising measure for efficient and immediate quality control and management, respectively. Wine quality and food safety may be increased. Fair and incentive pricing of delivered grapes may be enabled.     

Light hydrocarbon geochemistry: insight into oils/condensates families and inferred source rocks of the Woodford–Mississippian tight oil play in North-Central Oklahoma,USA

The Woodford–Mississippian Commingled Production is a prolific unconventional hydrocarbon play in Oklahoma, USA.The tight reservoirs feature variations in produced fluid chemistry usually explained by different possible source rocks.Such chemical variations are regularly obtained from bulk, molecular, and isotopic characteristics. In this study, we present a new geochemical investigation of gasoline range hydrocarbons, biomarkers, and diamondoids in oils from Mississippian carbonate and Woodford Shale. A set of oil/condensate samples were examined using high-performance gas chromatography and mass spectrometry. The result of the condensates from the Anadarko Basin shows a distinct geochemical fingerprint reflected in light hydrocarbon characterized by heptane star diagrams, convinced by biomarker characteristics and diamantane isomeric distributions. Two possible source rocks were identified, the Woodford Shale and Mississippian mudrocks,with a variable degree of mixing. Thermal maturity based on light hydrocarbon parameters indicates that condensates from the Anadarko Basin are of the highest maturity, followed by Old Woodford-sourced oils and central Oklahoma tight oils.These geochemical parameters shed light on petroleum migration within Devonian–Mississippian petroleum systems and mitigate geological risk in exploring and developing petroleum reservoirs.