Gas Purge–Microsyringe Extraction Coupled with Liquid Chromatography and Fluorescence Detection for the Determination of Aldehydes from Fried Meat

In this study, a green, simple, and sensitive method was developed for the analysis of aliphatic aldehydes from fried meat by using a modified gas purge–microsyringe extraction (GP–MSE) system in combination with high-performance liquid chromatography (HPLC) with fluorescence detection. The modified GP–MSE system possessed two gas channels and showed better recoveries for compounds with diverse density in comparison with one gas channel GP–MSE system. Target compounds in fried meat were effectively extracted without the traditional solvent extraction and lipid removing process, while the HPLC sensitivity of aldehydes was enhanced by introducing 2-(12-benzo[b]acridin-5(12H)-yl)-acetohydrazide (BAAH) with excellent fluorescence property into the molecules. Parameters influencing the extraction efficiency and HPLC sensitivity were optimized. The limits of detection (LODs) ranged from 0.30 to 0.45 μg/kg, and the limits of quantification (LOQs) ranged from 1.0 to 1.5 μg/kg. The recoveries of the target compounds were in the range of 86.9 to 95.6%. The proposed method was successfully applied to the analysis of aldehydes in fried meat samples. Formaldehyde, acetaldehyde, pentanal, hexanal, heptanal, octanal, nonaldehyde, and decanal were all found in fried meat samples with concentrations ranging from 0.05 to 17.8 mg/kg.     

Determination of 103 Pesticides and Their Main Metabolites in Animal Origin Food by QuEChERS and Liquid Chromatography–Tandem Mass Spectrometry

A rapid and sensitive analytical multiresidue method has been developed for the simultaneous determination of 103 pesticides (herbicides, insecticides, and fungicides) and 18 metabolites in foods of animal origin using liquid chromatography-tandem with triple quadrupole in dynamic multiple reaction monitoring (DMRM) mode. A modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) sample preparation technique was established, and the efficiency of the dispersive solid-phase extraction (d-SPE) cleanup step was evaluated by comparing the effects of different d-SPE sorbent combinations (primary secondary amine (PSA) + graphitized carbon black (GCB), PSA + C18, C18, and C18 + GCB). The limits of quantification (LOQs) ranged from 1 to 10 μg/kg, and the coefficient of determination (R ²) was ≥0.995 within the calibration linearity range of 0–250 μg/L for all pesticides. The combination of C18 + GCB was validated at two spiking levels (10 and 50 μg/kg) in chicken, fish, pork, and rabbit. Satisfactory recoveries (70–119%) and RSDs ≤17% were achieved for all analytes, except for naptalam (60–69%), pyrimethanil (40–49%), and thiabendazole (62–66%) at 10 μg/kg spiking level. The validated method was successfully applied to the analysis of real samples of food of animal origin.     

Front-Face Fluorescence Spectroscopy as a Rapid and Non-Destructive Tool for Differentiating Between Sicilo–Sarde and Comisana Ewe’s Milk During Lactation Period: A Preliminary Study

The objective of this study was to assess the potential of front-face fluorescence spectroscopy for differentiating between two genotypes (Comisana and Sicilo–Sarde) of ewe’s milk collected during lactation period. Physico-chemical analyses and fluorescence spectra were performed on milk samples during the first 15 weeks of lactation period. Regarding fluorescence spectra, aromatic amino acids and nucleic acids (AAA+NA), tryptophan, and vitamin A were recorded on milk samples after excitation set at 250, 290, and 322 nm, respectively. Emission spectra of vitamin A were scanned after emission set at 410 nm. Among the investigated intrinsic probes, only the principal component analysis (PCA) performed on AAA+NA allowed a good discrimination between milks produced from Comisana and those collected from Sicilo–Sarde ewes. Also, the PCA carried out on the physico-chemical parameters did not allow any discrimination between milk samples according to their genotypes. It can be concluded that emission spectra of AAA+NA could be considered as fingerprints allowing a good identification of milk samples according to ewe’s genotypes.     

Application of GC–MSD and LC–MS/MS for the determination of priority pesticides in baby foods in Serbian market

Babies and small children are especially sensitive population to the exposure to environmental contaminants. Their small mass and developing systems, including brain development may show adverse health effects from even low levels of contamination on a chronic or single dose case. In this paper one extraction method and two chromatographic techniques for the determination of pesticide residues in baby food were evaluated. A liquid chromatography–tandem mass spectrometry technique combined with electrospray ionization (ESI), (LC–MS/MS) and gas chromatography–mass spectrometry detection (GC–MSD) technique were applied in the detection of 50 pesticides in baby food. So-called QuEChERS (quick, easy, cheap, effective, rugged and safe) method was used as a sample preparation procedure. The recoveries were investigated at three levels (5, 10 and 50 μg/kg) and the results obtained showed compliance with the contemporary EU requirements with a few exceptions. LOQs for most of the tested pesticides were below the EU MRLs (10 μg/kg), except deltamethrin, cypermethrin, fenvalerate, phosalone and beta-cyfluthrin (LOQs were 10 μg/kg). Both techniques were applied in the analysis of 50 samples of baby food manufactured in Serbia.     

Application of Matrix Solid-Phase Dispersion and Liquid Chromatography–Ion Trap Mass Spectrometry for the Analysis of Pesticide Residues in Fruits

This study presents an application of rapid and sensitive multiresidue method for the analysis of acephate, acetamipride, atrazine, carbendazim, carbaryl, carbofuran, dimethoate, imidacloprid, linuron, malathion, monocrotophos, monuron, propazine, simazine, and tebufenozide in fruits. The method involves an extraction procedure based on matrix solid-phase dispersion using diatomaceous earth as a dispersant and dichloromethane as the eluent. The target pesticides were determined using liquid chromatography–ion trap mass spectrometry. Quantification of the analytes was carried out using the most sensitive ion transition. Ion trap parameters, like activation q and time, were found to have a prominent influence on method sensitivity for some pesticides and they were optimized accordingly. The confirmation of residues detected in real samples was performed by repeated injection and acquiring additional ion transitions besides the ones used for quantification. The method was validated for accuracy, linearity, reproducibility, and sensitivity. Mean values for recoveries were in the range of 70–120 % for all tested matrices. Repeatability of the method, expressed as the relative standard deviation, was in general lower than 20 %. The applicability of the method to routine analysis was tested in real fruit samples with good performance.     

High-Performance Liquid Chromatography with Fluorescence Detection for Simultaneous Analysis of Phytosterols (Stigmasterol, β-Sitosterol,Campesterol, Ergosterol,and Fucosterol) and Cholesterol in Plant Foods

A method based on high-performance liquid chromatography (HPLC) with fluorescence (FL) detection for the simultaneous analysis of phytosterols (stigmasterol, β-sitosterol, campesterol, ergosterol, and fucosterol) and cholesterol was developed. To fluoresceinate the sterols, they were derivatized by 1-anthroyl cyanide to the hydroxyl group at carbon 3 of each sterol skeleton. This HPLC-FL method consists of a C-30 column, an isocratic solution using acetone/acetonitril/hexane/water (71:20:4:5, v/v) as the mobile phase at 1.0 mL min^?1 and fluorescence detection at an excitation of 370 nm and an emission of 470 nm. The separation of five phytosterols, cholesterol, and 1-hexacosanol as an internal standard was achieved with sufficient reproducibility and quantitative ability. Our method could evaluate the sterols of land plants such as wood ear fungus, soybean, and parsley, as well as marine algae such as Hiziki (Phaeophyta), Ogonori (Rhodophyta), and Heraiwazuta (Chlorophyta). As a result of the analysis of land plants, wood ear contained a large amount of ergosterol as a precursor of vitamin D₂. Soybean contained a large amount of stigmasterol, campesterol, and β-sitosterol. Parsley contained small amounts of these sterols compared with wood ear and soybean. Among the marine algae, Hiziki, Ogonori, and Heraiwazuta contained large amounts of fucosterol, cholesterol, and β-sitosterol, respectively. The compositions of marine algae differed from those of land plants.     

Comparison of Simple and Rapid Extraction Procedures for the Determination of Pesticide Residues in Fruit Juices by Fast Gas Chromatography–Mass Spectrometry

Three sample treatment methods, based on QuEChERS, solid-phase extraction (SPE) and solid-phase microextraction (SPME), were compared and evaluated in order to obtain the best conditions to determine pesticide residues in fruit juice by fast gas chromatography–mass spectrometry (single quadrupole GC-MS). Analysis were performed under selected ion monitoring, acquiring the three most abundant and/or specific ions for each analyte and using their relative intensity ratios as a confirmatory parameter. The 3 methodologies (QuEChERS, SPE and SPME) were validated taking 15 selected pesticides as model compounds, using commercial apple juice. QuEChERS procedure was based on the AOAC Official Method 2007.01, using acetonitrile (containing 1 % acetic acid) as extraction solvent and primary–secondary amine during the dispersive solid-phase extraction. Oasis hydrophilic–lipophilic balance cartridges were used for SPE, and polyacrylate fibers were used for direct immersion SPME procedure. Three isotopically labeled standards were added to the samples before extraction and used as surrogate standards. Validation parameters as recoveries, limits of detection, and limits of quantification (LOQ), as well as matrix effects and sample throughput, were obtained and compared for the three extraction procedures. QuEChERS was considered faster and led to the best quantitative results. In this way, validation was extended to up to 56 pesticides by applying QuEChERS in multi-fruit juice samples, obtaining LOQs ranging from 2 to 20 μg/L for most compounds. Accuracy and precision were evaluated by means of recovery experiments at two concentration levels (10 and 100 μg/L), obtaining recoveries between 70 and 120 % in most cases and relative standard deviations below 15 %. Finally, the QuEChERS method was applied to the analysis of commercial juices, including mango–apple, pineapple, grapefruit and orange.     

Application and Optimization of Microwave-Assisted Extraction and Dispersive Liquid–Liquid Microextraction Followed by High-Performance Liquid Chromatography for the Determination of Oleuropein and Hydroxytyrosol in Olive Pomace

In the present study, a new method based on microwave-assisted extraction and dispersive liquid–liquid microextraction (MAE–DLLME) followed by high-performance liquid chromatography (HPLC) was proposed for the separation and determination of oleuropein (Ole) and hydroxytyrosol (HyT) from olive pomace samples. The effective factors in the MAE–DLLME process such as microwave power, extraction time, the type and volume of extraction, and dispersive solvents were studied and optimized with the aid of response surface methodology (RSM) based on a central composite design (CCD) to obtain the best condition for Ole and HyT extraction. At the optimized conditions, parameter values were 220 W microwave power, 12 min extraction time, 60 μL extracting solvent, and 500 μL dispersive solvent. The calibration graphs of the proposed method were linear in the range of 10–500,000 μg L^?1, with the coefficient of determination (R²) higher than 0.99 for Ole and HyT. Repeatability of the method, described as the relative standard deviation (RSD), was 4.12–5.63% (n?=?6). The limits of detection were 35 and 20 μg L^?1 for Ole and HyT, respectively. The recoveries of these compounds in the spiked olive pomace sample were from 93 to 98%. The proposed method, MAE–DLLME–HPLC–UV, was an accurate, rapid, and reliable method when compared with previous methods.     

Application of Dispersive Liquid–Liquid Micro-extraction Using Mean Centering of Ratio Spectra Method for Trace Determination of Mercury in Food and Environmental Samples

In the present study, dispersive liquid–liquid micro-extraction has been applied for trace extraction and determination of mercury (Hg) ions in environmental samples. The mean centering of ratio spectra method was used to optimize the experimental parameters affecting the extraction of Hg. The factors influencing the extraction procedure such as type and volume of extracting and disperser solvent, concentration of chelating reagent, pH, salt effect, and centrifuge time were investigated and optimized. Under the optimized conditions, the limit of detection of the method was 0.15 μg l^?1 and enrichment factor was 39. The calibration curve was linear in the range of 0.5–100 μg l^?1 with a correlation of determination (R ²) of 0.998. The relative standard deviation for determination of 40 μg l^?1 of Hg(II) was 2.6 % (n?=?5). The proposed method was applied for the determination of Hg in pine leaf, sea and river fish, sand, and water samples as indicators of environmental pollution and cigarette with satisfactory analytical results. In comparison with other methods, the proposed method is very simple, easy, rapid, and sensitive for determination of Hg at trace levels in complex matrices.     

A Biotin–Streptavidin Amplified Enzyme-Linked Immunosorbent Assay with Improved Sensitivity for Rapid Detection of Ractopamine in muscular tissue Development and Nonspecific Adsorption Reduction

An effective biotin–streptavidin amplified enzyme-linked immunosorbent assay (BA-ELISA) was optimized and characterized for the rapid detection of Ractopamine (RAC) residue in muscular tissue. Purification of the RAC antiserum by protein A-Sepharose 4B followed with bovine serum albumin (BSA)-Sepharose 4B affinity chromatography enhanced the sensitivity and reduce the background adsorption. Blocking with 0.5% skimmed milk power and diluting streptavidin–HRP conjugates with 0.5% BSA/phosphate-buffered saline (PBS) effectively remove the nonspecific adsorption in biotin–streptavidin amplified ELISA system. The established method allowed RAC determination with an IC₅₀ value of 0.3 ± 0.02 ng ml⁻¹ and a limit of detection of 0.02 ± 0.003 ng ml⁻¹, more sensitive than the other reported methods. The variation coefficients of intra-assay and inter-assay were all below 7%. RAC residue in pig muscular tissue could be quantified without matrix effects after a 5-fold extraction and 2-fold dilution with PBS. Recoveries of RAC in pig muscular tissue ranged from 75% to 82.75%. The results were also compared with those from HPLC and a good correlation was obtained (r ² = 0.9822). The characters show that the established biotin–streptavidin amplified ELISA could be potentially useful in rapid detection of RAC in animal-derived foods.     

Application of Fast Gas Chromatography–Mass Spectrometry in Combination with the QuEChERS Method for the Determination of Pesticide Residues in Fruits and Vegetables

A fast gas chromatography–mass spectrometry method has been developed for multiresidue determination of up to 56 pesticides in fruits and vegetables in a chromatographic run time of <10 min, using a single quadrupole mass spectrometer operating in selected ion monitoring mode. The well-known acetate-buffering version of the QuEChERS method has been used for sample preparation. Programmable temperature vaporizer injection of 3 μL allowed reaching limits of detection between 0.15 and 15 μg/kg for most compounds in the sample matrices tested. The applicability of the method has been evaluated in apple, orange, carrot, and tomato. Recoveries at three fortification levels (0.01, 0.1 and 0.5 mg/kg) ranged from 70 to 120 % for most compounds, with relative standard deviations below 20 % in all cases. The developed method has been applied to fruit and vegetable samples from different Spanish provinces.     

A Rapid and Sensitive Method for Determination of Melamine in Fish,Shrimp, Clam,and Winkle by Gas Chromatography–Mass Spectrometry with Microwave-Assisted Derivatization

A method for rapid and sensitive determination of melamine in aquatic products by gas chromatography–mass spectrometry with microwave-assisted derivatization was proposed in this paper. Melamine was extracted from aquatic product samples using methanol, and the extract was cleaned with a mixed-mode cationic exchange solid phase extraction column. After elution with 5 % ammonia–methanol solution and drying with nitrogen, the residue was derivatized using N,O-bis(trimethylsilyl)trifluoroacetamide containing 1 % trimethylchlorosilane under microwave irradiation for 1 min with a power of 420 W, then detected with gas chromatography–mass spectrometry, and quantified by the external standard method. Some important parameters such as extraction solvent, microwave irradiation power and time, and derivatization reagent volume were investigated and optimized. The results showed that methanol could effectively extracted melamine from aquatic products as well as precipitated the protein in samples. Under the optimum conditions, the detection limit for melamine was as low as 0.006 mg/kg, and the linear range was from 0.02 to 50 mg/kg with a correlation coefficient of 0.9997. The proposed method was applied to the analysis of melamine in aquatic products (fish, shrimp, clam, and winkle), and the recovery for melamine was 89.65–105.16 % with relative standard deviation of 3.0–6.0 %.     

Application of Box–Behnken Design in the Optimization of In Situ Surfactant-Based Solid Phase Extraction Method for Spectrophotometric Determination of Quinoline Yellow in Food and Water Samples

In this work, a simple, rapid and sensitive method using in situ surfactant-based solid phase extraction (ISS-SPE) combined with UV–vis spectrophotometry has been developed for the preconcentration and determination of trace amounts of quinoline yellow in food and water samples. The Box–Behnken design was employed to optimize the extraction efficiency. The variables of interest were pH, surfactant volume, extraction time and NaI volume. In the optimal conditions, the calibration graph was linear in the range of 10.0–750 μg L^?1 with a correlation coefficient of 0.9982. The limit of detection (LOD) was 2.1 μg L^?1, and the preconcentration factor was calculated to be 51.8.     

Extraction and Preconcentration of Some Triazole Pesticides in Grape Juice by Salting Out Homogeneous Liquid–Liquid Extraction in a Narrow-Bore Tube Prior to Their Determination by Gas Chromatography–Flame Ionization Detection

A fast and simple extraction and preconcentration method for some triazole pesticides has been developed using a homogeneous liquid–liquid extraction method performed in a narrow-bore tube. The extraction is based on phase separation of a water-miscible organic solvent from aqueous solution in the presence of a salting out agent. In this work, the homogeneous solution of water and acetonitrile (water-soluble extraction solvent) was broken by addition of 30 %, w/v, sodium chloride (salting out agent). After sonication, a small volume of acetonitrile was collected on top of the tube and the extracted analytes in the collected phase were determined by gas chromatography–flame ionization detection. The effect of various experimental parameters including kind and volume of the water-soluble organic solvent, amount of salt, length and diameter of tube, and pH of sample solution was investigated. Under the optimum conditions, calibration graphs were linear over the range of 3–5,000 μg L^?1. Relative standard deviations were less than 5.4 % for six repeated determinations (C?=?100 μg L^?1). Furthermore, the limits of detection (S/N?=?3) and quantification (S/N?=?10) were obtained in the ranges of 0.60–4.8 and 1.9–16 μg L^?1, respectively. This method is very simple and rapid, requiring less than 10 min for sample preparation. It has been successfully utilized for the analysis of triazole pesticides in the grape juice samples.     

High-Performance Liquid Chromatography with Fluorescence Detection for Simultaneous Analysis of Retinoids (Retinyl Palmitate,Retinyl Acetate,and Free Retinol) and α-, β-, γ-, and δ-Tocopherols in Foods

A method based on high-performance liquid chromatography with fluorescence detection for the simultaneous analysis of retinoids (vitamin A) and tocopherols (vitamin E) was developed. This method consists of an isocratic solution using hexane/ethyl acetate (85:15, v/v) as the mobile phase and fluorescence detection using a time program that sets the excitation (Ex) and emission (Em) wavelengths at adequate elution times for retinoids (Ex 342 nm, Em 476 nm) and tocopherols (Ex 298 nm, Em 325 nm), respectively. The separation of three retinoids (retinyl palmitate, retinyl acetate, and free retinol) and four tocopherol homologs was achieved with sufficient reproducibility and quantitative ability. Additionally, the necessity of saponification was considered. As a result, saponification was not used in this method because of the complexity of the procedure and the loss of free retinol. The retinoid and tocopherol contents of various foods were evaluated using the developed method. Our method could evaluate the retinoid and tocopherol contents of fish (eel, Anguilla japonica, and amberjack, Seriola dumerili) muscle and liver, roasted soybean (Glycine max) flour, and Japanese torreya seed (Torreya nucifera). Additionally, our method could be applied to the determination of retinoids and tocopherols not only in foods but also in supplements and cosmetics.     

Development and validation of a new LC–MS/MS method for the simultaneous determination of six major ergot alkaloids and their corresponding epimers. Application to some food and feed commodities

A liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed and validated for the simultaneous determination of six major ergot alkaloids, ergometrine, ergosine, ergotamine, ergocornine, ergokryptine and ergocristine, as well as their corresponding epimers in food and feed samples. The method involves extraction under alkaline conditions and subsequent clean-up by applying a simple and rapid liquid–liquid partitioning procedure prior to LC–MS/MS analysis. Evaluation of the method revealed good linearity, accuracy and precision. The limits of quantification varied from 0.1 to 1 μg/kg depending on the analyte and matrix. The average extraction and clean-up recoveries in different matrices were between 45 (only for ergometrine in biscuit) and 90%. The uncertainty associated with the analytical method was not higher than 51% and 30%, at concentration levels of 2.5 and 150 μg/kg respectively. Analyte epimerization proved to be minimal during the analytical procedure. The method has been successfully applied to the determination of ergot alkaloids in some Belgian food and feed commodities. Ergot alkaloids were found in 104 out of 122 samples investigated. Ergosine was the most frequently occurring alkaloid, while the highest levels were observed for ergotamine, ergocristine or ergosine, depending on the product type. The total alkaloid content in positive samples varied from 1 to 1145 μg/kg.