Compounds In Food Samples Research Articles

Study of Organochlorinated Pesticide Residues and PCBs in Vegetable and Fruit Samples from market in Peja –Kosovo

Organoclorine pesticides (OCP) are the first class of compounds of synthetic pesticides introduced in agricultural and civil uses to counteract noxious insects and insect-born disease. In general they are lipophilic compounds with noticeable chemical and environmental stability. They tend to concentrate in the higher trophic organisms, as they amplify through the food chain. Food is generally recognized as the main source of human intake of pesticides, their metabolites and their residues. Preparation of samples, especially in food samples for quantitative analysis of organochlorined pesticides has an important role in recognizing the real levels. For the analysis of these micro-trace compounds in food samples is a constant search for new analytical methods. The most important steps of their chemical analysis usually are the extraction, purification, fractionation and concentration.In this study, were analyzed samples of fruit and vegetables from the market of Peja, Kosovo in September 2011. Ultrasonic extraction was used for extracting pesticide residues from samples. Clean-up procedure was performed using firstly sulfuric acid followed a second clean-up procedure in an “open” florisil column. The organochlorine pesticides detected were HCHs (a-, b-, γ- and d-isomers) and the DDT-related chemicals (o,p-DDE, p,p-DDE, p,p-DDD, p,p-DDT), hexachlorobenzene (HCB), heptachlor, heptachlor epoxide, methoxychlor and Aldrine’s. Analyses were done with capillary column Rtx-5, 60m long, 0.32mm internal diameter, 0.25 μm film thicknesses on a gas chromatograph Dani 1000, with μECD detector. The found concentrations of the chlorinated pesticides were lower than accepted levels for studied samples

Active Packaging for Fresh Food Based on the Release of Carvacrol and Thymol

Active packaging is becoming an emerging food technology to improve quality and safety of food products. One of the most common approaches is based on the release of antioxidant/a ntimicrobial compounds from the packaging material. In this work an antifungal active packaging system based on the release of carvacrol and thymol was optimized to increase the post-harvest shelf life of fresh strawberries and bread during storage. Thermal properties of the developed packaging material were determined by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Volatile compounds in food samples contained in active packaging systems were monitored by using headspace solid phase microextraction followed by gas chromatography analysis (HS-SPME-GC-MS) at controlled conditions. The obtained results provided evidences that exposure to carvacrol and thymol is an effective way to enlarge the quality of strawberries and bread samples during distribution and sale.

Development of high performance liquid chromatography‐ultraviolet detection method for screening mebendazole, clorsulon, diaveridine, and tolfenamic acid in animal‐based food samples

This study focused on the detection and validation of the residues of the four veterinary drugs, mebendazole, clorsulon, diaveridine, and tolfenamic acid, using high performance liquid chromatography (HPLC) and an ultraviolet (UV) detector. Utilizing C18 column as a stationary phase and applying appropriate mobile phases to each analysis according to the properties of the analytes, target compounds in food samples were successfully detected and separated within 15-50 min. Additionally, in order to optimize detection, liquid-liquid extraction (LLE) and purification steps were established to minimize the endogenous peaks and their interferences. The method was validated through testing of linearity, accuracy, precision, the limit of detection (LOD) and the limit of quantification (LOQ). The LOQ levels of the four drugs were lower than the maximum residual limit, and the coefficient of determination (R(2) ) was over 0.99. The recovery results ranged from 82.3-105.2%, 79.3-83.3%, 79.4-86.0%, and 81.7-88.5% with relative standard deviations lower than 20% for mebendazole, clorsulon, diaveridine, and tolfenamic acid, respectively, corresponding to the CODEX guideline. This proposed method reduces costs and enables easier application in rural or remote areas where testing facilities or instruments often are unavailable.

Carvacrol and Thymol for Fresh Food Packaging

Active packaging is becoming an emerging food technology to improve quality and safety of food products. One of the most common approaches is based on the release of antioxidant/antimicrobial compounds from the packaging material. In this work an antifungal active packaging system based on the release of carvacrol and thymol was optimized to increase the post-harvest shelf life of fresh strawberries and bread during storage. Thermal properties of the developed packaging material were determined by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Volatile compounds in food samples contained in active packaging systems were monitored by using headspace solid phase microextraction followed by gas chromatography analysis (HS-SPME- GC-MS) at controlled conditions. The obtained results provided evidences that exposure to carvacrol and thymol is an effective way to enlarge the quality of strawberries and bread samples during distribution and sale.

Microwave-assisted extraction performed in low temperature and in vacuo for the extraction of labile compounds in food samples

In this study, low temperature vacuum microwave-assisted extraction, which simultaneous performed microwave-assisted extraction (MAE) in low temperature and in vacuo environment, was proposed. The influencing parameters including solid/liquid ratio, extraction temperature, extraction time, degree of vacuum and microwave power were discussed. The predominance of low temperature vacuum microwave-assisted extraction was investigated by comparing the extraction yields of vitamin C, β-carotene, aloin A and astaxanthin in different foods with that in MAE and solvent extraction, and 5.2–243% increments were obtained. On the other hand, the chemical kinetics of vitamin C and aloin A, which composed two different steps including the extraction step of analyte transferred from matrix into solvent and the decomposition step of analyte degraded in the extraction solvent, were proposed. All of the decomposition rates ( K 2) for the selected analyte in low temperature, in vacuo and in nitrogen atmosphere decreased significantly comparing with that in conventional MAE, which are in agreement with that obtained from experiments. Consequently, the present method was successfully applied to extract labile compound from different food samples. These results showed that low temperature and/or in vacuo environment in microwave-assisted extraction system was especially important to prevent the degradation of labile components and have good potential on the extraction of labile compound in foods, pharmaceutical and natural products.

Fast liquid chromatography/tandem mass spectrometry (highly selective selected reaction monitoring) for the determination of toltrazuril and its metabolites in food

In this work a fast liquid chromatography (LC)-tandem mass spectrometry (MS/MS) method was developed for the analysis of toltrazuril, a coccidiostatic drug, and its metabolites in meat food products. The applicability of atmospheric pressure chemical ionization (APCI) and heated electrospray ionization in both positive and negative modes was studied. APCI in negative mode provided the best results and the base peak originated from the loss of CF(3) (toltrazuril and toltrazuril sulfone) and CHF(3)* (toltrazuril sulfoxide) was used as the precursor ion in MS/MS. A fast LC separation on a C(18) Fused-Core column was used together with the APCI-MS/MS method developed using enhanced mass resolution mode (highly selective selected reaction monitoring, H-SRM) to improve the sensitivity and selectivity for the analysis of these compounds in food samples. A simple sample treatment based on an extraction with acetonitrile and a cleanup with a C(18) cartridge was used. The LC-MS/MS (H-SRM) method showed good precision (relative standard deviation lower than 10%), accuracy, and linearity and allowed the determination of these compounds in food samples down to the parts per billion level (limits of detection between 0.5 and 5 microg kg(-1)).

Neural Network Analysis of Spectroscopic Data of Lycopene and β-Carotene Content in Food Samples Compared to HPLC-UV-Vis

In this study a neural network (NN) model was designed to predict lycopene and beta-carotene concentrations in food samples, combined with a simple and fast technique, such as UV-vis spectroscopy. The measurement of the absorbance at 446 and 502 nm of different beta-carotene and lycopene standard mixtures was used to optimize a neural network based on a multilayer perceptron (MLP) (learning and verification process). Then, for validation purposes, the optimized NN has been applied to determine the concentration of both compounds in food samples (fresh tomato, tomato concentrate, tomato sauce, ketchup, tomato juice, watermelon, medlar, green pepper, and carrots), comparing the NN results with the known values of these compounds obtained by analytical techniques (UV-vis and HPLC). It was concluded that when the MLP-NN is used within the range studied, the optimized NN is able to estimate the beta-carotene and lycopene concentrations in food samples with an adequate accuracy, solving the UV-vis interference of beta-carotene and lycopene.

Determination of alkenylbenzenes and related flavour compounds in food samples by on-column preconcentration-capillary liquid chromatography

A new, simple and versatile method is presented for the determination of different concentration levels of alkenylbenzenes (eugenol, isoeugenol, eugenol methyl ether, myristicin, anethole and estragole) and the related flavour compounds (coumarin and pulegone) in food samples. The method involves the use of a stationary phase (capillary column) for the enrichment with appropriate elution. After the sample had completely passed through the capillary column the eluent was changed and the separation/detection was achieved. Excellent linearity was obtained under the proposed conditions for a direct determination method and a method including on-line preconcentration. The limits of detection were in the ranges 97–148 and 9.5–14.2 ng/mL, respectively. Evidence for a matrix effect was not found and recoveries between 92 and 110% were obtained. The precision of the method, expressed as relative standard deviation values, was below 5% in all cases. The applicability of this methodology was tested by analyzing synthetic and real food samples.

Simultaneous determination of inositol and inositol phosphates in complex biological matrices: quantitative ion‐exchange chromatography/tandem mass spectrometry

myo-Inositol (Ins) and myo-inositol phosphates (InsPs) are widely distributed in plants and animals. The evaluation of the distribution of Ins and InsPs in cells and plant sources can impact the understanding of their role in nutrition, cellular processes and diseases, and how they may be modulated by diet. We developed an anion-exchange chromatography/tandem mass spectrometry (HPLC/ESI-MS/MS) method for the separation and simultaneous quantitation of Ins and different naturally occurring phosphorylated inositol compounds. Chromatographic separation was achieved in 30 min on a commercial anion-exchange column (0.5 x 150 mm) using a gradient of 200 mM ammonium carbonate buffer (pH 9.0) and 5% methanol in H(2)O. Analytes were identified by selective reaction monitoring using a triple quadrupole mass spectrometer in negative ion electrospray ionization mode. Adenosine 5'-monophosphate was used as a general internal standard for quantitation. Detection is linear in the range of 0.25-400 pmol for Ins, InsP(1), InsP(4), and InsP(5), 40-400 pmol for InsP(2) and InsP(3), and 60-400 pmol for InsP(6), with a minimum r(2) > 0.994. The limit of detection is 0.25 pmol with a signal-to-noise ratio of 10:1 for all analytes. The intra-day and inter-day variations were within 17% at three concentration levels. Recovery values for the seven analytes spiked into extraction solution or different matrices were between 63 and 121%. Using this approach, Ins and InsPs were measured in three different plant samples and in cultured cells, illustrating significant differences in the distribution of inositol compounds in food samples compared to cells and between cell types.

Determination of trace food-derived hazardous compounds in Chinese cooked foods using solid-phase extraction and gas chromatography coupled to triple quadrupole mass spectrometry

Gas chromatography coupled to tandem mass spectrometry (GC–MS/MS) with a triple quadrupole analyzer (QqQ) was applied for the first time to the determination of trace food-derived hazardous compounds in food samples. Thirteen heterocyclic amines were confirmed and quantified by the developed sensitive method. The method includes a solid-phase extraction procedure with a polystyrene copolymer cartridge (LiChrolut EN), followed by a derivatization reaction with N,N-dimethylformamide di-tert-butylacetal. Analyses were performed by gas chromatography with triple quadrupole mass spectrometry in the electron impact mode. The MS/MS fragmentation pathway of derived heterocyclic amines was studied and the differences of fragmentation characteristics were used successively to distinguish the isomers in absence of chemical standards. The excellent selectivity and sensitivity achieved in multiple reaction monitoring mode allowed us satisfactory quantitation and confirmation. The limits of quantitation of the method for these compounds ranged from 0.12 to 0.48ng/g of sample. The method developed was applied to the analysis of Chinese cooked foods, and the results demonstrated the potentiality of the GC–MS/MS method for the analysis of trace food-derived hazardous compounds in complex food matrices such as meat samples.

Rapid determination of hazardous compounds in food based on a competitive fluorescence microsphere immunoassay

Development of a microsphere-based competitive fluorescence immunoassay for the determination of hazardous low-molecular-weight compounds in food is described. In this method, antigens are covalently bound to carboxy-modified microspheres to compete monoclonal antibody with low-molecular-weight compounds in food samples; mouse IgG/fluorescein isothiocyanate conjugate is used as the fluorescent molecular probe. Thus, the hazardous low-molecular-weight compounds are quantified using a multiparameter flow cytometer. This method has been evaluated using clenbuterol as a model compound. It has a sensitivity of 0.01 ng/mL with dynamic range of 0.01–100 ng/mL, and the concentration of clenbuterol providing 50% inhibition (IC 50) is 1.1 ng/mL. The main advantages of this method are its high efficiency, biocompatibility, and selectivity, as well as ultralow trace sample consumption and low cost.

Determination of 2-isopropyl thioxanthone and 2-ethylhexyl-4-dimethylaminobenzoate in milk: comparison of gas and liquid chromatography with mass spectrometry

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) and gas chromatography-mass spectrometry (GC-MS) have been compared for the analysis of 2-isopropyl thioxanthone (ITX) and 2-ethylhexyl-4-dimethylaminobenzoate (EHDAB). Pressurized liquid extraction (PLE) was applied for the extraction of ITX and EHDAB from milk and milk-based beverages. Samples were homogenized with sea sand and anhydrous sodium sulfate, and were extracted with ethyl acetate at 100 degrees C and 10.3 x 10(6) Pa in one cycle of 10 min at 90% flush. Both, GC-MS and LC-MS/MS were suitable to determine these photoinitiators in the PLE extracts, providing appropriate identification and quantification. The recoveries obtained ranged from 70 to 99% for ITX and from 70 to 95% for EHDAB. These recoveries were equal as those obtained by a conventional liquid-liquid partitioning with acetonitrile and tert-butyl methyl ether-hexane. The quantification limits using GC-MS, based on a signal-to-noise ratio of 10, were 0.5 microg/L for ITX and 1 microg/L for EHDAB. The repeatability of the method, as indicated by the relative standard deviations, was within the range 0.9-16.1%. The same parameters calculated using LC-MS/MS result in quantification limits of 0.1 microg/L for ITX and 0.02 microg/L for EHDAB and repeatability within the range 5.2-19.4%. These results pointed out that both techniques are appropriate to determine these compounds in food samples. The method was applied to milk and milk-based beverages from different supermarkets. The ITX and EHDAB contents ranged from 2.5 to 325 microg/L and from 8 to 126 microg/L, respectively.

A Screen‐Printed, Amperometric, Biosensor Array for the Detection of Organophosphate Pesticides Based on Inhibition of Wild Type, and Mutant Acetylcholinesterases, from Drosophila melanogaster

Screen‐printed carbon electrodes (SPCEs) modified with cobalt phthalocyanine (CoPC) have been used as base transducers in the construction of amperometric pesticide biosensors. Six individual biosensors were fabricated by depositing wildtype (WT) acetylcholinesterase (AChE) from Drosophila melanogaster or one of five mutant forms (B02, B03, B04, B421, and B65) of this enzyme, onto the surfaces of CoPC‐SPCEs; these constituted the amperometric biosensor array. The enzyme converts acetylthiocholine into its electroactive product thiocholine, which is detected at only 0 V vs. Ag/AgCl at the CoPC‐SPCEs. The measurement step is performed using chronoamperometry. In the presence of an organophosphate (OP) pesticide, the enzyme is inhibited, which leads to a decrease in thiocholine production and a corresponding decrease in anodic current. This decrease is proportional to the logarithm of the pesticide concentration. Calibration studies were performed with the biosensor array using five OPs of interest to the food industry, namely omethoate, malaoxon, dichlorvos, chlorpyrifos‐methyl‐oxon, and pirimiphos‐methyl‐oxon. It was found that different inhibition patterns occurred for the five OPs indicating the possibility of identifying and quantifying these compounds in food samples. It should be added that there was no detrimental affect on the biosensor response from wheat or apple extracts.

A review of theoretical and practical aspects of solid‐phase microextraction in food analysis

SummarySolid‐phase microextraction (SPME) is a modern, solvent‐free sample preparation technique, commonly used in trace analysis. This technique has been developed to combine sampling and sample preparation in one step. This paper reviews selected theoretical and practical aspects of the SPME method used for the isolation and preconcentration of impurities, food constituents, additives and flavour compounds in food samples. The main parameters affecting the extraction effectiveness are discussed and exemplified by selected chromatograms. The review is intended for readers who are either new to the field of SPME or its use in food analysis and many examples of its application for different food matrices are listed.

Matrix solid phase dispersion as an effective preparation method for food samples and plants before HPLC analysis - a riview

This review deals with a preparation technique – Matrix Solid Phase Dispersion (MSPD) and its possibilities in the HPLC analysis for contaminants, pesticides, drug residues, and natural compounds in food samples. The main principle of MSPD is explained, the important factors influencing the effectivity and recovery of this technique are discussed. The advantages and disadvantages of MSPD and other classical extraction, isolation, and purifica­tion procedures are compared. The present article provides a bibliography of MSPD applications in food sample matrices during last years for various analytes and different sample matrices.  

Fast determination of procyanidins and other phenolic compounds in food samples by micellar electrokinetic chromatography using acidic buffers.

Procyanidins are phenolic oligomers, mainly composed of (+)-catechin and (-)-epicatechin units that exhibit certain sensorial and physiological properties of interest (e.g., astringency and bitterness of food, antioxidant activity, etc.). This paper shows the development of a micellar electrokinetic chromatography (MEKC) method for the separation of three procyanidin dimers (B1, B2, and B3), their monomers ((+)-catechin and (-)-epicatechin), and the cis- and trans-forms of p-coumaric acid. Separation conditions are optimized in terms of buffer pH, SDS concentration, and washing routine between injections. The best results in terms of peak resolution and reproducibility between separations were obtained with a MEKC running buffer at pH 5 with 100 mM SDS and a washing routine that includes a rinse step with 0.1 M sodium hydroxide. Using this new MEKC method it is possible to separate in less than 5 min the seven substances. More interestingly, it is demonstrated that the low pH used in this MEKC method allows one to obtain clean electropherograms when samples are injected. The method is shown to be reproducible between different days with relative standard deviation (RSD) values lower than 1% for migration times and lower than 7% for peak areas (3 days, 24 injections). The usefulness of this procedure to determine these compounds in effluents from food processing (i.e., soaking water from lentils, white beans and black beans) and in food by-products (i.e., almond peels) considered as potential procyanidin sources is demonstrated. To our knowledge, this is the first report of separation and determination of procyanidins in food samples done by capillary electrophoresis.

Study on simultaneous determination methods for anions by capillary electrophoresis.

Simultaneous determination methods for anions were studied by capillary electrophoresis(CE).First, a CE method for the analysis of inorganic and organic anions which have UV absorbance was developed by using a polymer-coated capillary.Next, CE methods for anions having little or no UV absorption were described.Each method was performed with indirect UV detection using 2, 6-pyridinedicarboxylic acid(PDC)and cetyltrimethylammonium salt as the background electrolyte(BGE).To avoid the adsorption of organic acids on the capillary, high complexing ability with metals was necessary for the BGE.The use of PDC provided a good sensitivity of organic acids.28 carbohydrates, such as acidic, neutral, amino sugars and sugar alcohols, could be analyzed with the same BGE at a pH of 12.1.Its utility was demonstrated in an analysis of monosaccharides of hydrolyzed glycoprotein and food samples.The high complex ability of PDC also enabled the simultaneous analysis of inorganic and organic anions, as well as metal cations.The PDC worked to confer a negative charge on metal cations via PDC-complex formation.Furthermore, this BGE system was evolved into the simultaneous analysis of 43 inorganic anions, organic acids, amino acids and carbohydrates and applied to the analysis of those compounds in food samples.

Determination of seven biogenic amines in foods by micellar electrokinetic capillary chromatography

Micellar electrokinetic capillary chromatography was applied to the separation of seven biogenic amines, most frequently occurring in foods. Putrescine, cadaverine, spermidine, spermine, tryptamine, histamine and tyramine were separated as N-substituted benzamides using an uncoated fused-silica capillary column (43 cm×75 μm I.D.). Borate buffer (15 m M) with sodium dodecylsulphate (40 m M) and methanol (25%, v/v) was found to be a suitable system for the determination of these compounds in food samples. The detection limits in the range of 0.2 to 0.7 mg l −1 are sufficient for this type of sample.

Determination of phenolic acids and tannins in soil water extracts using the technicon autoanalyzer ii system

Abstract A manual colorimetric procedure for determination of phenolic compounds in food samples was modified for automated analysis of soil water extracts using the Technicon Autoanalyzer II (AA II). The Folin Denis color reagent consists of a mixture of molybdic and tungstic complexes which are reduced to oxides by phenolic acids. The oxides form blue salts under alkali conditions. This reaction was assumed to be specific to the hydroxy and methoxy bonds of phenolic acids. EDTA was added to complex calcium and magnesium in the sample extracts, which otherwise would have interfered with the colorimetric reaction. The method was useful for tracing the disappearance of 11 individual phenolic acids added to soil samples. Accurate measurement of the total concentration of mixed phenolic acids was not possible because of variation in the degree of color development between phenolic acids. The method was sensitive to tannic acid in soil water extracts.

The occurrence of preformed N-nitroso compounds in food samples from a high risk area of esophageal cancer in Kashmir, India

Several commonly used raw foodstuffs from a high risk esophageal cancer region in Kashmir (India) were analysed for the presence of N-nitroso compounds. The food items were selected on the basis of their frequent consumption with particular emphasis on the preserved foods (dried, pickled and smoked) and those which are unique to the region. Nine out of 11 food items were found to contain low concentrations of N-nitrosodimethylamine (NDMA), N-nitrosopyrrolidine (NPYR), N-nitrososarcosine (NSAR), N-nitrosoproline (NPRO) and N-nitrosothaizolidine-4-carboxylic acid (NTCA). The preliminary survey shows a widespread contamination of N-nitroso compounds in raw foodstuffs from Kashmir.