Determination of Chloramphenicol in Honey, Shrimp, and Poultry Meat with Liquid Chromatography–Mass Spectrometry: Validation of the Method According to Commission Decision 2002/657/EC

Chloramphenicol (CAP) is an antibiotic used for the treatment of bacterial infections in human and veterinary medicine. The use of CAP was prohibited in the European Union in 1994. Control laboratories are required to use suitably validated analytical methods to check sample compliance with the regulation. A quantitative method based on liquid chromatography coupled to isotopic dilution tandem mass spectrometry was developed for the determination of chloramphenicol in honey, shrimp, and poultry meat. The experimental protocol consisted of a liquid–liquid extraction with ethyl acetate. Separation and detection were realized, respectively, by a 2690 Waters HPLC (Milford, MA, USA) and a Micromass Triple Quadrupole mass spectrometer (Micromass, Manchester, UK), equipped with an electrospray source. The effects of mobile-phase additives on the response of LC/ESI/MS were examined. Two different HPLC columns were tested: the X-Terra from Waters and the Alltima HP C18 HL from Alltech (Deerfield, IL, USA). A validation of the method was conducted according to the EU criteria for the analysis of chloramphenicol in foods. The decision limits (CCα) were 0.04, 0.03, 0.07 μg?kg^?1, and the detection capabilities (CCβ) were 0.05, 0.04, 0.08 μg?kg^?1 for honey, shrimp, and poultry meat, respectively. Those values are below the minimum required performance limit set at 0.3 μg?kg^?1 by the EU and 0.1 μg?kg^?1 by Belgium. Our protocol has the advantage to propose a unique extraction method working as well for honey, shrimp, and poultry meat, contrary to similar published methods in which a different extraction method is used for each type of matrix.     

Ultrasound-Assisted Extraction Followed by Solid-Phase Extraction Followed by Dispersive Liquid–Liquid Microextraction for the Sensitive Determination of Diazinon and Chlorpyrifos in Rice

Selectivity of solid-phase extraction (SPE) was combined with the concentration power of dispersive liquid–liquid microextraction (DLLME) to obtain a sensitive, low solvent consumption method for high-performance liquid chromatography determination of diazinon and chlorpyrifos in rice. In this method, rice samples were extracted by ultrasound-assisted extraction followed by SPE. Then, the SPE eluent was used as a disperser solvent in the next dispersive liquid-liquid microextraction step for further purification and enrichment of diazinon and chlorpyrifos. Under the optimal conditions, the linear range was from 5.0 to 250 μg kg^?1 for diazinon and from 2.5 to 250 μg kg^?1 for chlorpyrifos. Limits of detection of diazinon and chlorpyrifos were 1.5 and 0.7 μg kg^?1, respectively. Limits of quantitation of diazinon and chlorpyrifos were 5.5 and 3.0 μg kg^?1, respectively. The precisions and recoveries also were investigated by spiking 10 μg kg^?1 concentration in rice. The recoveries obtained were over 90 % with relative standard deviation (RSD%) below 9.0 %. The new approach was utilized to successfully detect trace amounts of diazinon and chlorpyrifos in different Iranian rice samples.     

Simultaneous Determination of Cyadox and Its Metabolites in Chicken Tissues by LC-MS/MS

A specific and sensitive LC-MS/MS method was firstly established for the simultaneous extraction and determination of cyadox and its three main metabolites—1,4-bisdesoxycyadox, 4-desoxycyadox, and quinoxaline-2-carboxylic acid—in chicken muscle, liver, kidney, and fat tissues. Samples were subjected to extraction using ethyl acetate and followed by acetonitrile–chloroform (1:4, v/v) and further purified by Oasis mixed mode anion exchange SPE cartridge. Analysis was performed on a C₁₈ column by detection with MS in multiple-reaction monitoring mode. A gradient elution program with 0.1 % formic acid solution, acetonitrile, and 1 % formic acid (adjusted to pH 8 with ammonia) was performed at a flow rate of 0.2 mL min^?1. The correlation coefficients (r) for each calibration curve are higher than 0.99 within the experimental concentration range. The recoveries of the four target analytes at three spiking levels of 2.5, 25 and 250 μg kg^?1 were between 74.5 and 93.8 %, with relative standard deviations less than 12 %. The decision limits (CCαs) of the four analytes in chicken edible tissues ranged from 0.3 to 1.5 μg kg^?1, and the detection capabilities (CCβs) were below 2.3 μg kg^?1. The developed method demonstrated a satisfactory applicability in incurred chicken tissue samples.     

Polyether ionophores residues in Minas Frescal cheese by UHPLC-MS/MS

ABSTRACT

An analytical method was developed and validated for the determination of three polyether ionophores (monensin, lasalocid, and salinomycin) in 60 samples of Brazilian Minas Frescal cheese by UHPLC-MS/MS. Linearity ranged from 1 to 8 μg kg^?1 for monensin and salinomycin, and from 0.50 to 4 μg kg^?1 for lasalocid. Limits of detection and quantitation were 0.50 μg kg^?1 and 1 μg kg^?1, respectively, for both monensin and salinomycin, and 0.25 μg kg^?1 and 0.50 μg kg^?1, respectively, for lasalocid. Recoveries were between 69% and 84% with coefficients of variation up to 16.28% for repeatability and 13.79% for intermediate precision. A total of 60 samples of Minas Frescal cheese were analysed and only monensin residues were found. Monensin was detected in 55% of the samples and quantified in 5 of them at mean levels varying from 1.00 to 1.73 μg kg^?1. The proposed method demonstrated the suitability for monitoring these substances in cheese.     

Preconcentration and Simultaneous Analysis of Benzimidazole Anthelmintics in Milk Samples by Ultrasound-Assisted Surfactant-Enhanced Emulsification Microextraction and High-Performance Liquid Chromatography

The proposed ultrasound-assisted surfactant-enhanced emulsification microextraction (UASEME) coupled with high-performance liquid chromatography-photodiode array detection (HPLC-PDA) has been developed for the preconcentration and simultaneous analysis of five benzimidazole anthelmintics. Dichloromethane (extraction solvent) and Triton X-114 (emulsifier) was used for extraction of the target analytes. The parameters affecting the extraction efficiency were investigated and optimized. Under the optimum conditions, linearity was in the range from 10 to 150 μg?L^?1 with good coefficients of determination (R ²) higher than 0.994. Preconcentration factors were obtained up to 60, corresponding to limits of detection range of 1.8???3.6 μg?L^?1. Intra-day (n?=?5) and inter-day (n?=?4?×?3) precisions were obtained with relative standard deviation of retention time and peak area below 0.8 and 9.2 %, respectively. Good recoveries for the spiked target anthelmintics at different concentrations (e.g., 20, 50, and 100 μg?L^?1) of milk samples were obtained in 72.5–113.5 %. The results demonstrated that the proposed UASEME-HPLC-PDA can be used as an alternative powerful method for the simultaneous determination of the target analytes in milk samples.     

Determination of Eugenol in Aquatic Products by Dispersive Solid-Phase Extraction and Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry

A novel procedure, dispersive solid-phase extraction coupled with ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), was developed for the determination of eugenol in aquatic products (shrimp, crab, and carp). Aquatic products were extracted with acetonitrile and primarily purified by dispersive solid-phase extraction with graphitized carbon black as absorbent. The pretreated acetonitrile extract was detected by UHPLC-MS/MS. UHPLC was carried out on Dikma Endeavorsil C₁₈ (30 mm × 2.1 mm, 1.8 μm) column eluted by methanol and water (80:20 v/v) at a rate of 0.30 mL min^?1. Tandem mass spectrometry was performed by electrospray ionization in negative ion mode to identify and quantify eugenol during multiple reaction monitoring. Under optimized analytical conditions, the matrix-matched spiked calibration sample demonstrates good linearity between 5.0 and 500.0 μg kg^?1 with a linear regression coefficient of 0.9996. The average recovery of eugenol from aquatic products is 95.3–103.4% at spiked levels between 5 and 50 μg kg^?1 with a relative standard deviation (n = 6) less than 5.4%. The limits of detection and quantification for eugenol were calculated to be 1.47 and 4.91 μg kg^?1, respectively. In comparison with those reported, the proposed method has advantages in low detection limit, high recovery, and short analysis time, meeting the requirements for the determination of trace eugenol residue in aquatic products.     

Simultaneous determination of pyrimethanil,cyprodinil, mepanipyrim and its metabolite in fresh and home-processed fruit and vegetables by a QuEChERS method coupled with UPLC-MS/MS

A QuEChERS procedure for the simultaneous determination of pyrimethanil, cyprodinil, mepanipyrim and its metabolite (M31) in fresh and processed fruit and vegetables was developed using ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS). The determination of the four target compounds was achieved in less than 6.0 min using an electrospray ionisation source in positive mode. The limits of detection (LODs) were below 0.4 μg?kg^?1, while the limits of quantification (LOQs) did not exceed 1.5 μg?kg^?1 for all studied matrices. Good linearity of the calibration curves was obtained over the range from 0.002 to 2 mg?kg^?1, with correlation coefficients higher than 0.999. The average recoveries of this method in apple, peach, cabbage and tomato at the five spiked levels (0.002, 0.01, 0.05, 0.20 and 2.0 mg?kg^?1) ranged from 81.5% to 107.3% with relative standard deviations (RSDs) in the range of 1.5–13.9% (n = 5) for all analytes. Residue levels of anilinopyrimidine fungicides in fresh and home-processed apple, peach, cabbage and tomato were also studied. The results indicate that residue levels are significantly reduced following washing, peeling and boiling, and there is no toxic metabolite of mepanipyrim (M31) which is detected during boiling. This study provides a theoretical basis for China to draw up maximum residue limits (MRLs) and protect consumers from the negative health effects of pesticide residues detected in fruit and vegetables.     

Applicability of Pressurized Liquid Extraction for Melamine Analysis in Pet Foods with High-Performance Liquid Chromatography with Diode Array Detection

A pressurized liquid extraction (PLE) method was developed for melamine analysis in pet foods. The PLE method which utilized an accelerated solvent extraction (ASE®) system was also compared with sonication and polytron extraction methods. The parameters for the optimized PLE method were temperature (75?°C for wet pet food, 125?°C for dry pet food), pressure (1,500 psi), static time (10 min), flush volume (40%), purge time (1 min), and number of cycles (1). Recoveries obtained by PLE method were significantly higher (P?≤?0.05) than those of sonication and polytron methods for dry pet food samples. For the analysis of adulterated pet foods, PLE resulted in the highest melamine content followed by sonication and polytron. Using PLE, samples fortified with melamine at 2.5 and 100 mg kg^?1 resulted in recoveries ranging from 55% to 90% for wet samples and from 90% to 116% for dry samples. Low recovery rate from wet samples at low spike level (2.5 mg kg^?1) may have been caused by co-aggregation of polysaccharide and protein with melamine due to low pH during solid-phase extraction cleanup. Limit of detection and limit of quantification values were 0.5 (mg kg^?1) and 1.0 (mg kg^?1) for dry samples. Overall, PLE had the best extraction efficiency compared to sonication and polytron, proving PLE to be a useful tool for melamine analysis of pet foods.     

Determination of Polycyclic Aromatic Hydrocarbons (PAH4) in the Traditional Lebanese Grilled Chicken: Implementation of New,Rapid and Economic Analysis Method

Polycyclic aromatic hydrocarbons (PAH4) (benzo[a]anthracene, chrysene, benzo[b]fluoranthene, and benzo[a]pyrene) are evaluated in a traditional and widely consumed staple in Lebanon “Lebanese Grilled Chicken.” Forty samples with different local additives grilled by charcoal were purchased from different restaurants located in different regions in Lebanon. For this purpose, a simple and a reliable analytical method based on sonication technique and gas chromatography coupled to mass spectrometer (GC-MS) has been developed and validated. Several parameters affecting the extraction efficiency, such as the nature and the volume of the extract solvent, as well as other factors were investigated and optimized. The developed method is environmentally and economically friendly with a minimized consuming time, consisting of a single sonication step for 15 min using 12 mL of non-carcinogenic solvent acetonitrile (ACN) and without any further concentration prior to analysis. Following extraction, the cleanup step was based on freezing and d-SPE by C18 addition. Under optimized conditions, the method performances were evaluated; the limits of quantification (LOQs) achieved were lower than 0.689 μg kg^?1, and these values fit the performance criteria for the method given by the EC that defined the LOQ values of PAH lower than 0.9 μg kg^?1. In addition, the recovery values of the analyzed PAHs ranged from 88.9 to 119.3% with relative standard deviations (RSDs) less than 8% (n = 15). The levels of PAH4 were in the range from 1.52 to 49.9 μg kg^?1, where about 40% of the Lebanese grilled chicken exceeded the EU commission MRLs of 12 μg kg^?1.     

Validated RP-HPLC Method for Simultaneous Determination of Tocopherols and Tocotrienols in Whole Grain Barley Using Matrix Solid-Phase Dispersion

The vitamers of vitamin E such as α-, β-, γ-, and δ-tocotrienol and α-, β-, γ-, and δ- tocopherol are important phytochemical compounds with antioxidant activity and with potential benefits for human health. A high-performance liquid chromatography with fluorescence detection (HPLC-FLD) method was validated for their determination in whole grain barley samples. Tocol extraction was performed by an optimized matrix solid-phase dispersion (MSPD) protocol with neutral alumina (0.5 g) as the dispersion agent and methanol (5 mL) as the elution solvent. The analytical column was an Eclipse XDB C18 column (150?×?4.6 mm, 5 μm) and it was operated at room temperature. Mobile phase was consisted of methanol/acetonitrile/i-propanol (55:40:5?v/v?%) and the elution was isocratic at a flow rate of 0.8 mL/min. Total analysis time was 12 min, and the detection of the tocols was performed with a fluorimetric detector where the excitation and emission wavelengths were set at 295 and 335 nm, respectively. Method validation was performed by means of intra-day (n?=?5) and inter-day accuracy and precision (n?=?8), sensitivity, and linearity. The linear regression coefficient (R ²) was higher than 0.99. The recoveries of the tocols from barley samples with the proposed extraction method were in an acceptable level (74–91 %) where the relative standard deviation ranged from 4.2 to 15.0 %. Limits of detection (LODs) and limits of quantification (LOQs) varied from 0.03 to 0.11 mg kg^?1 and 0.11 to 0.34 mg kg^?1, respectively.     

Simultaneous Determination of Multiclass Pesticides and Antibiotics in Honey Samples Based on Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry

A simple, fast, and efficient method was developed for simultaneous determination of 79 pesticides and 13 antibiotics compounds of different chemical classes of pesticides and antibiotics in honey samples by ultra-high performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS). The sample preparation procedure includes homogenization with McIlvaine buffer 0.1 mol L^?1 (pH 4), followed by extraction with acetonitrile and cleanup with florisil, using dispersive solid phase extraction (d-SPE). The proposed method was validated with good results, such as linearity (r ²?>?0.9901), normality, and independence of the evaluated data, as well as recoveries between 70 and 120 % with relative standard deviation (RSD) <20 % for most of the compounds spiked from 0.1 to 200 μg kg^?1. The experimental method limits of detection and quantification were from 0.03 to 1.51 μg kg^?1 and from 0.1 to 5 μg kg^?1, respectively, for the pesticides. For the antibiotics, the decision limits (0.1 to 2 μg g^?1) and the detection capacity (0.12 to 2.81 μg g^?1) were below the maximum residue limits (MRLs) established for honey by the Brazilian and European legislation. The method was successfully applied to real samples from different botanical and geographic origins. From them, 44 % presented residues from 0.12 to 10 μg kg^?1 of one or more analytes. The proposed method combines the advantages of a quick sample preparation step with the selectivity and sensitivity of the UHPLC-MS/MS and proved to be suitable for routine analyses.     

Determination of Pesticide Residues in Golden Berry (<Emphasis Type="Italic">Physalis peruviana</Emphasis> L<Emphasis Type="Italic">.</Emphasis>) by Modified QuEChERS Method and Ultra-High Performance Liquid Chromatography-Tandem Quadrupole Mass Spectrometry

A fast and effective multiresidue method for the determination of 42 pesticides in golden berry was developed and validated. A modified QuEChERS method was established for sample preparation followed by ultra-high performance liquid chromatographic-tandem mass spectrometry (UHPLC-MS/MS) determination with electrospray ionization in a triple quadrupole system. Validation results were satisfactory, since the method presented recoveries between 70 and 114 % with relative standard deviations (RSD) <20 % for blank samples spiked from 5 to 25 μg kg^?1. The method limit of detection and limit of quantification were 1.5 and 5 μg kg^?1 _, respectively. Matrix effect ranged from ?32 to 218 % and was compensated using matrix-matched calibration. Method linearity was established from 2.5 to 100 μg kg^?1 with r ² ≥ 0.99. The proposed method combines the advantages of a simple and fast sample preparation step by a modified QuEChERS method with the high selectivity and sensitivity of the UHPLC-MS/MS system using selected reaction monitoring. The method was successfully applied to commercial samples, proving to be an efficient alternative for routine analysis. From the 16 analyzed samples, 13 presented residues of one or more pesticides (carbendazim, chlorpyrifos ethyl, dimethoate, propamocarb, and tebuconazole) in the concentration range of 2.0 to 55.6 μg kg^?1.     

Occurrence of glyphosate in beer from the Latvian market

A sensitive LC-MS/MS method for the determination of glyphosate in beer has been developed, validated, and applied to analyse 100 beer samples from 24 different producers and distributors in Latvia. The selected samples represented most beer brands and varieties sold in local supermarkets. Different procedures for sample preparation and chromatographic separation were compared. The final version of the method consisted of solid phase extraction, chromatographic separation on aminopropyl stationary phase, and detection using tandem mass spectrometry. The concentration of glyphosate in beer varied from below the LOD of 0.2 μg kg^?1 up to 150 μg kg^?1, higher than previously reported. Significantly higher (p < 0.01) content of glyphosate was observed in beers that did not have the country of production disclosed on the label and were sold in local supermarkets by distributors from Latvia (1.8 μg kg^?1 median concentration in locally produced beer, 6.7 μg kg^?1 in beer of undisclosed origin).     

Occurrence of patulin and 5-hydroxymethylfurfural in apple sour,which is a traditional product of Kastamonu,Turkey

Apple sour is a traditional product of Kastamonu, Turkey. It is consumed by spreading on bread or drinking after diluting with water. The aim of this study was to determine patulin (PAT) and 5-hydroxymethylfurfural (HMF) in apple sour. This study is the first to evaluate the occurrence of PAT and HMF in apple sour. The samples were extracted with ethyl acetate using liquid-liquid extraction technique. PAT and HMF were determined by HPLC with UV detection. PAT was detected in all samples, and the PAT level in 94.9% of samples was found to be equal or greater than the legal limit for juice concentrates. The mean value for PAT was found to be 284 ± 307 μg kg^?1. PAT levels in 13 of 39 samples were in the range of 100 ≤ x < 200 μg kg^?1, two samples were in the range of 0 ≤ x < 50 μg kg ?1 and two samples were in the range of 1000 ≤ x < 1500 μg kg¹. HMF levels of all samples were above the legal limit for solid molasses. The mean value for HMF was found to be 16215 ± 13317 mg kg^?1. HMF levels of 10 of 39 samples were determined to be in the range of 10000 ≤ x < 20000 mg kg^?1, eight samples were in the range of 20000 ≤ x < 30000 mg kg^?1 and only three samples were in the range of 100 ≤ x < 1000 mg kg^?1. There was a significant and inverse relationship between HMF and pH of the samples. These results indicate that consumption of apple sour is a considerable risk in terms of HMF and PAT toxicity.     

A Highly Sensitive Method for the Determination of Thiophanate Methyl,Cyromazine, and Their Metabolites in Edible Fungi by Ultra-Performance Liquid Chromatography Using Accelerated Solvent Extraction and Cleanup with Solid-Phase Extraction

A highly sensitive ultra-performance liquid chromatographic method with diode-array detection was developed for residue determination of thiophanate methyl (TM), cyromazine (CYR), and their metabolites, carbendazim (MBC) and melamine (MEL). Edible fungi samples were treated using accelerated solvent extraction (ASE) followed by cleanup with solid-phase extraction (SPE). Under optimized conditions, good linearity was achieved with a correlation coefficient (r ²) of ≥0.9998. The limit of quantification was 0.36, 0.24, 0.4, and 0.5 μg kg^?1 for MEL, CYR, MBC, and TM, respectively. The intra- and interday precisions (in terms of the relative standard deviation (RSD)) of the four analytes were in the range of 2.3–4.5 and 3.1–6.3 %, respectively. The recoveries for TM, MBC, CYR, and MEL in four edible fungi samples at three spiked levels of 0.6, 6, and 20 μg kg^?1 for TM and MBC and 0.4, 4, and 20 μg kg^?1 for CYR and MEL were in the range of 82–105 % with RSDs below 5.6 %. The proposed method can be used for the routine determination of CYR and MEL in edible fungi with high sensitivity and accuracy as well as low consumption of reagents.     

Determination of Hormones Residues in Milk by Gas Chromatography-Mass Spectrometry

The article presents the use of gas chromatography-mass spectrometry (GC-MS) technique in a method for the determination of 18 anabolic hormones from synthetic stilbenes, steroids and resorcylic acid lactones (RALs) groups in raw milk and milk powder. Sample preparation consisted of liquid-liquid extraction with diethyl ether and purification by solid phase extraction (SPE). Prior to instrumental analysis, the reaction of derivatisation with the heptafluorobutyric anhydride or N-methyl-N-trimethylsilyltrifluoroacetamide was performed. Method validation was carried out according to the required performance criteria of the Commission Decision 2002/657/EC. The apparent recovery of all analytes at 1 μg L^?1 (kg^?1) level was ranged between 70.4 and 119.4 % with the coefficients of variation values less than 30 %. The decision limits (CCα) and the detection capabilities (CCβ) were in the range of from 0.11 to 0.44 μg L^?1 (kg^?1) and from 0.19 to 0.75 μg L^?1 (kg^?1), respectively. The procedure has been accredited and successfully applied as a screening method for the presence of hormone residues in the study of commercial samples of milk.     

Determination of Trichothecenes in Cereal Matrices Using Subcritical Water Extraction Followed by Solid-Phase Extraction and Liquid Chromatography-Tandem Mass Spectrometry

Subcritical water extraction followed by solid-phase extraction and ultra-high performance liquid chromatography coupled with tandem mass spectrometry detection is reported for the first time for the determination of 6 trichothecenes (deoxynivalenol, deoxynivalenol-3-glucoside, 3-acetyl-deoxynivalenol, 15-acetyl-deoxynivalenol, HT-2 toxin, and T-2 toxin) from different cereals. Water with 1% formic acid was used as the extraction solvent followed by a solid-phase extraction clean-up, achieving good performance with acceptable extraction recoveries, method detection limits between 0.05 μg kg^?1 and 4.0 μg kg^?1, and method quantification limits between 0.4 μg kg^?1 and 20 μg kg^?1. The use of water as the extraction solvent allowed a selective extraction affording low matrix effect levels and the detection and quantification of natural target trichothecenes at very low concentration levels. This extraction method was applied to different cereals, a pseudocereal and an oilseed sample, of which maize, millet, and oat were contaminated by at least one trichothecene.     

Ultrasonic-Assisted Extraction of α-Tocopherol Antioxidants from the Fronds of Elaeis guineensis Jacq.: Optimization, Kinetics, and Thermodynamic Studies

This article presents the first report on the extraction and quantification of α-tocopherol from the fronds of the oil palm (Elaeis guineensis Jacq). In this study, the optimization, kinetic, and thermodynamic data of α-tocopherol extraction by sonication are presented. Response surface methodology coupled with central composite design was used to optimize the experimental conditions for α-tocopherol extraction. Three independent variables, namely sample/solvent ratio (1:20–1:40 g/ml), extraction temperature (30–50 °C), and extraction time (20–50 min) were studied. For optimum conditions of 39.31 °C (~40 °C), 50 min, and 1:23.63 g/mL (~1:20 g/mL), total tocols and α-tocopherol optimal concentrations were 346.49 μg/g oil palm fronds (OPFs) by dry weight (DW) and 28.41 μg/g OPF DW, respectively. The effects of extraction temperature and tocol concentrations on the extraction kinetics and thermodynamic parameters were also studied. From the mass transfer rate equation, the kinetic and thermodynamic data obtained from the ultrasonic-assisted extraction (UAE) of α-tocopherol from OPF were activation energy, E _a (104.6 kJ mol^?1), UAE rate constant, k (6.886?×?10^?3 min^?1), ΔH (+0.818 kJ mol^?1), ΔS (+27.22 J mol^?1 K^?1), and ΔG (?8.52 J mol^?1). According to this study, the UAE of α-tocopherol from OPF is endothermic, irreversible, and spontaneous.     

Simultaneous Determination of Eight Tranquilizers in Pork by Ultra-Performance Liquid Chromatography Coupled with Electrospray Tandem Mass Spectrometry

An ultra-performance liquid chromatography/electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) method was developed and validated for quantification of eight tranquillizers (chlorpromazine, imipramine hydrochloride, diazepam, nitrazepam, nordazepam, oxazepam, flurazepam, and haloperidol) in pork. Sample pretreatment consisted of extraction by acetonitrile, defatted by n-hexane, and further solid phase extraction by hydrophilic-lipophilic balance (HLB) extraction cartridges. The triple quadrupole mass spectrometer was operated in positive ion mode, and multiple reaction monitoring was used for drug quantification. The method was validated over the concentration ranges of 1.0 ～ 250 μg kg^?1 for the eight tranquillizers. The calibrations were performed in sample matrices, and the interference effect of sample matrices on the ionization was effectively eliminated. Good linear relationship (R ² > 0.99) was observed within the concentration range of 1.0–250 μg kg^?1. The average recoveries of the eight tranquillizers spiked at three levels ranged from 63.7 to103.2 % with the relative standard deviation below 11.8 %. The limits of detection were between 0.06 and 0.30 μg kg^?1, and the limits of quantification were between 0.2 and1.0 μg kg^?1 for all analytes in pork. This validated method has been successfully used to quantify the concentration of the eight tranquillizers in pork samples.     

Metal levels in Trachurus trachurus and Cyprinus carpio in Turkey

Concentrations of five toxic metals were determined in two fish species from Turkish cities during 2010–2011. The obtained lead concentrations for all of the studied Trachurus trachurus (mean 777 μg kg^?1) and Cyprinus carpio (mean 439 μg kg^?1) samples were found to be higher than the maximum level (ML) of 300 μg kg^?1, while Cd concentrations in the same samples were lower than the ML. Mean chromium (501 μg kg^?1), Ni (272 μg kg^?1) and Cu (785 μg kg^?1) concentrations in T. trachurus were significantly higher than in C. carpio (336 μg Cr kg^?1, 229 μg Ni kg^?1 and 394 μg Cu kg^?1), similar to those of Pb and Cd. Measured Pb concentrations in T. trachurus tissues are significantly higher than the ML, while those of Cd in both T. trachurus and C. carpio species were lower than the ML values.