Solid phase extraction as sample treatment for the determination of Ochratoxin A in foods: A review.

Posted on 30 May, 2017 by fqm302

Ochratoxin A (OTA) is a mycotoxin produced by two main types of fungi, Aspergillus and Penicillium species. OTA is a natural contaminant found in a large number of different matrices and is considered as a possible carcinogen for humans. Hence, low maximum permitted levels in foods have been established by competent authorities around the world, making essential the use of very sensitive analytical methods for OTA detection. Sample treatment is a crucial step of analytical methodology to get clean and concentrated extracts, and therefore low limits of quantification. Solid phase extraction (SPE) is a useful technique for rapid and selective sample preparation. This sample treatment enables the concentration and purification of analytes from the sample solution or extract by sorption on a solid sorbent. This review is focused on sample treatment procedures based on SPE prior to the determination of OTA in food matrices, published from 2010.

Posted in Food, Mycotoxins, Review, SPE | Tagged | Comments Off on Solid phase extraction as sample treatment for the determination of Ochratoxin A in foods: A review.

Evaluation of direct analysis in real time for the determination of highly polar pesticides in lettuce and celery using modified Quick Polar Pesticides Extraction method

Posted on 5 April, 2017 by fqm302

Direct analysis in real time (DART) was evaluated for the determination of a number of highly polar pesticides using the Quick Polar Pesticides Extraction (QuPPe) method. DART was hyphenated to high resolution mass spectrometry (HRMS) in order to get the required selectivity that allows the determination of these compounds in complex samples such as lettuce and celery. Experimental parameters such as desorption temperature, scanning speed, and distances between the DART ion source and MS inlet were optimized. Two different mass analyzers (Orbitrap and QTOF) and two accessories for sample introduction (Dip-it® tips and QuickStrip™ sample cards) were evaluated. An extra clean-up step using primary-secondary amine (PSA) was included in the QuPPe method to improve sensitivity. The main limitation found was in-source fragmentation, nevertheless QuPPe-DART-HRMS proved to be a fast and reliable tool with quantitative capabilities for at least seven compounds: amitrole, cyromazine, propamocarb, melamine, diethanolamine, triethanolamine and 1,2,4-triazole. The limits of detection ranged from 20 to 60 μg/kg. Recoveries for fortified samples ranged from 71 to 115%, with relative standard deviations <18%.

Posted in AGL2015-70708-R, Celery, DART, Lettuce, Polar, QuPPe | Tagged , | Comments Off on Evaluation of direct analysis in real time for the determination of highly polar pesticides in lettuce and celery using modified Quick Polar Pesticides Extraction method

Validation of a new method based on salting-out assisted liquid-liquid extraction and UHPLC-MS/MS for the determination of betalactam antibiotics in infant dairy products

Posted on 7 March, 2017 by fqm302

In this work a new multiresidue method has been developed for the determination of 15 betalactam antibiotics in infant milk and yogurt based on follow-on milk by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The separation was achieved in 6 min, using a Kinetex Biphenyl Core-Shell column (50 mmx2.1 mm, 1.7 µm), with a mobile phase of water with 0.05% acetic acid and methanol. The analytes were detected in ESI+ with multiple reaction monitoring mode and fragmentation conditions were optimized to obtain the highest sensitivity. The use of a biphenyl bonded column allowed to obtain a satisfactory selectivity for all the studied analytes. Moreover, ion-pair salting-out assisted liquid-liquid extraction (IP-SALLE) has been proposed as sample treatment and optimized by means of experimental design. Under optimum conditions, the recoveries for fortified samples ranged from 79% to 93%, (RSD <7.5%). The limits of quantification were lower than 9.0 µg kg−1, showing the high sensitivity and applicability of this fast and simple method. The results in terms of analysis time, sensitivity and accuracy showed the suitability of this procedure for the monitoring of betalactam residues in different infant foods.

Posted in Mass spectrometry, Milk, P12-AGR-1647, SALLE, UHPLC, Yogurt, β-lactams | Tagged , , | Comments Off on Validation of a new method based on salting-out assisted liquid-liquid extraction and UHPLC-MS/MS for the determination of betalactam antibiotics in infant dairy products

Determination of benzimidazoles in meat samples by capillary zone electrophoresis tandem mass spectrometry following dispersive liquid–liquid microextraction.

Posted on 1 March, 2017 by fqm302

A novel method based on capillary zone electrophoresis-tandem mass spectrometry has been proposed and validated for the identification and simultaneous quantification of twelve benzimidazoles in meat samples. Electrophoretic separation was carried out using 500 mM formic acid (pH 2.2) as background electrolyte and applying a voltage of 25 kV at 25° C. In order to improve the sensitivity, stacking mode injection was applied, using as injection solvent a mixture of 30:70 acetonitrile/water at 50 mbar for 75 s. Sensitivity enhancement factors from 74 to 317 were obtained under these conditions. Detection using an ion trap as analyzer, operating in multiple reactions monitoring mode was employed. The main MS/MS parameters as well as the composition of the sheath liquid and other electrospray variables were optimized in order to obtain the highest sensitivity and precision in conjunction with an unequivocal identification. The method was applied to poultry and pork muscle samples. The deproteinization of samples and extraction of benzimidazoles was carried out with acetonitrile. MgSO4 and NaCl were added as salting-out agents. Subsequently, dispersive liquid–liquid microextraction was applied as clean up procedure. The organic layer (acetonitrile, used as dispersant) containing the benzimidazoles was mixed with the extractant (chloroform) and both were injected in water, producing a cloudy solution. Recoveries for fortified samples were higher than 70%, with relative standard deviations lower than 16% were obtained in all cases. The limits of detection were below 3 μg kg−1, demonstrating the applicability of this fast, simple, and environmentally friendly method.

Posted in Benzimidazoles, CZE, DLLME, Mass spectrometry, P12-AGR-1647, Pork muscle | Tagged , , | Comments Off on Determination of benzimidazoles in meat samples by capillary zone electrophoresis tandem mass spectrometry following dispersive liquid–liquid microextraction.

Use of onion extract as a dairy cattle feed supplement: monitoring propyl propane thiosulfonate as a marker of its effect on milk attributes.

Posted on 28 February, 2017 by fqm302

Onion extract is used as a feed supplement for the diet of dairy cows, acting as inhibitor of methane production; however, its properties could alter sensory attributes of milk. In this work, we propose a method to evaluate the influence of this extract on milk properties, using propyl propane thiosulfonate (PTSO) as a marker. PTSO is extracted using a quick, easy, cheap, effective, rugged, and safe procedure and monitored by high-performance liquid chromatography with ultraviolet detection. The method was applied to milk samples obtained from 100 dairy cows fed during 2 months with enriched feed. In addition, a milk tasting panel was established to evaluate the PTSO residue that should not be exceeded to guarantee milk sensory attributes. It was established that a value of PTSO lower than 2 mg kg–1 does not alter milk organoleptic properties. This fact makes onion extract an interesting alternative as a feed supplement to control the methane emissions without any influence on milk attributes.

Posted in Animal feed, HPLC, PTSO, QuEChERS, UV-vis | Tagged , , | Comments Off on Use of onion extract as a dairy cattle feed supplement: monitoring propyl propane thiosulfonate as a marker of its effect on milk attributes.

High-throughput methodology for the determination of carbamates in food supplements by UHPLC–MS/MS.

Posted on 28 February, 2017 by fqm302

Food supplements are increasingly consumed products that claim to have several benefits for health. In many cases, these supplements contain herbal products and, as a consequence, can be contaminated with pesticides used in crops. This study aimed to use a QuEChERS-based method and ultra-high performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS) to determine carbamate residues in different food supplements, all of them containing different herbal products, such as Garcinia cambogia, Cynaras colymus, Equisetum arvense, soy lecithin, Spirulina maxima, Fucus vesiculosus, olive leaf and garlic extract. After testing different sorbents, the combination of PSA/C18 (75/25) provided the best clean-up effect. The method was validated in terms of linearity, matrix effect, limit of quantification, precision (intra and interday) and trueness. Good linearity (r2 > 0.99) and precision lower than 16% (expressed as relative standard deviation) were obtained in all cases. Moreover, the recovery in all studied samples was within the acceptable range (71–104%), and limit of quantification was 0.8 µg kg−1. The method was proved to be successful as a quantitative method for carbamate residue analysis in various food supplements, which are known to be complex matrices.

Posted in AGL2015-70708-R, Carbamates, Mass spectrometry, QuEChERS, Supplements, UHPLC | Tagged , , | Comments Off on High-throughput methodology for the determination of carbamates in food supplements by UHPLC–MS/MS.

Evaluation of a new modified QuEChERS method for the monitoring of carbamate residues in high-fat cheeses by using UHPLC–MS/MS.

Posted on 27 February, 2017 by fqm302

A simple and efficient method for the determination of 28 carbamates in high-fat cheeses is proposed. The methodology is based on a modified quick, easy, cheap, effective, rugged, and safe procedure as sample treatment using a new sorbent (Z-Sep+) followed by ultra-high performance liquid chromatography with tandem mass spectrometry determination. The method has been validated in different kinds of cheese (Gorgonzola, Roquefort, and Camembert), achieving recoveries of 70–115%, relative standard deviations lower than 13% and limits of quantification lower than 5.4 μg/kg, below the maximum residue levels tolerated for these compounds by the European legislation. The matrix effect was lower than ±30% for all the studied pesticides. The combination of ultra-high performance liquid chromatography and tandem mass spectrometry with this modified quick, easy, cheap, effective, rugged, and safe procedure using Z-Sep+ allowed a high sample throughput and an efficient cleaning of extracts for the control of these residues in cheeses with a high fat content.

Posted in Carbamates, Cheese, Mass spectrometry, P12-AGR-1647, QuEChERS, UHPLC | Tagged , , | Comments Off on Evaluation of a new modified QuEChERS method for the monitoring of carbamate residues in high-fat cheeses by using UHPLC–MS/MS.

Development of magnetic molecularly imprinted polymers for selective extraction: determination of citrinin in rice samples by liquid chromatography with UV diode array detection.

Posted on 23 January, 2017 by fqm302

In this work, we report the synthesis of novel magnetic molecularly imprinted polymers (m-MIPs) and their application to the selective extraction of the mycotoxin citrinin (CIT) from food samples. The polymers were prepared by surface imprinting of Fe3O4 nanoparticles, using 2-naphtholic acid (2-NA) as template molecule, N-3,5-bis(trifluoromethyl)phenyl-N‘-4-vinylphenyl urea and methacrylamide as functional monomers and ethyleneglycol dimethacrylate as cross-linker. The resulting material was characterized by transmission electron microscopy (TEM), and X-ray diffraction (XRD) and Fourier transform infrared spectroscopies (FT-IR). The polymers were used to develop a solid-phase extraction method (m-MISPE) for the selective recovery of CIT from rice extracts prior to its determination by HPLC with UV diode array detection. The method involves ultrasound-assisted extraction of the mycotoxin from rice samples with (7:3, v/v) methanol/water, followed by sample cleanup and preconcentration with m-MIP. The extraction (washing and elution) conditions were optimized and their optimal values found to provide CIT recoveries of 94–98 % with relative standard deviations (RSD) less than 3.4 % (n = 3) for preconcentrated sample extracts (5 mL) fortified with the analyte at concentrations over the range 25–100 μg kg−1. Based on the results, the application of the m-MIPs facilitates the accurate and efficient determination of CIT in rice extracts.

Posted in HPLC, MIPs, Mycotoxins, Rice, UV-vis | Comments Off on Development of magnetic molecularly imprinted polymers for selective extraction: determination of citrinin in rice samples by liquid chromatography with UV diode array detection.

Metodologías avanzadas para la determinación de 5-nitroimidazoles en muestras alimentarias, ambientales y clínicas.

Posted on 16 January, 2017 by fqm302

The goals of this Thesis are within the scopes of several research projects carried out in the last years and included within the research lines of the group in which this Thesis has been
performed.

The main goal has been the development of novel, sensitive and selective analytical methods for the determination of several drugs belonging to the antibiotic family called 5-nitroimidazoles (5-NDZs). These compounds are prescribed in human medicine but their use in veterinary medicine is forbidden in the European Union. However, their use is allowed in other countries, so the control of their residues in food is a requirement in order to guarantee that current legislation is enforced. For such a reason, in this Thesis, several methods have been developed for the determination of 5-NDZ residues, including their metabolites, and which are suitable for their application in drug monitoring in biological fluids, food safety and residue determination in environmental field. Miniaturized techniques such as capillary electrophoresis (CE), capillary electrochromatography (CEC), and capillary liquid chromatography (CLC), as well as a high efficiency technique such as ultra-high performance liquid chromatography (UHPLC), have been selected for accomplishing this purpose. These techniques have been coupled to different detection techniques such as ultraviolet-visible (UV-Vis) spectrophotometry and tandem mass spectrometry (MS/MS). Furthermore, both on-line preconcentration (in the case of CE) and off-line preconcentration methods have been proposed, allowing sensitivity enhancement. Moreover, they result in new, more efficiency and environmental-friendly sample treatments for the analysis of 5-NDZ residues, according to the current trends in Green Chemistry.

The following specific goals of this Thesis must be remarked:

  1. Determination of 5-NDZs by CE-UV in environmental water samples and food products of animal origin, considering both off-line and on-line preconcentration techniques for overcoming the lack of sensitivity attributed to CE-UV.
  2. Demonstration of the potential of CE-MS/MS hyphenation for the control of
    5-NDZ residues in biological fluids, considering the identification capacity of the
    selected detection.
  3. Proposal of an efficiency procedure for packing capillaries for their further
    application in CEC and consequently, evaluation of the potential of this technique
    coupled to UV detection for the determination of 5-NDZs.
  4. Evaluation of CEC-MS hyphenation for the therapeutic monitoring of these drugs
    (research carried out in the group of Dr. Salvatore Fanali during a predoctoral stay
    in the ‘Istituto di Metodologie Chimiche (IMC) of Consiglio Nazionale delle Ricerche di
    Montelibretti’, Rome, Italy).
  5. Use of CLC for the determination of 5-NDZs in food products as alternative to
    traditional HPLC.
  6. Investigation of the advantages of UHPLC coupled to both UV and MS/MS
    detection, for the quick quantification of 5-NDZ residues in products of animal
    origin intended to human consumption.
  7. Proposal of new, simple, quick, selected and environmental-friendly simple treated
    for the determination of 5-NDZs, including their metabolites, as alternative to the
    methods that have been previously reported. Evaluation of these simple
    treatments in different matrices with the aim of demonstrating their suitability in
    terms of selectivity and sensitivity.
Posted in Theses | Comments Off on Metodologías avanzadas para la determinación de 5-nitroimidazoles en muestras alimentarias, ambientales y clínicas.

Determination of aflatoxins in yogurt by dispersive liquid – liquid microextraction and HPLC with photo-induced fluorescence detection.

Posted on 16 January, 2017 by fqm302

A high-performance liquid chromatography (HPLC) method with fluorescence detection for the determination of aflatoxins B1, B2, G1, G2, and M1 in yogurt using dispersive liquid–liquid microextraction as alternative sample treatment has been developed. To enhance the fluorescence of aflatoxins B1 and G1, a post-column photochemical derivatization has been proposed, avoiding the use of derivatization reagents. The method was validated using natural yogurt as representative matrix, showing a good linearity in the studied range (25–500 ng kg−1) and limits of quantification below the maximum level established by European Union in milk for the manufacture of milk-based products. Satisfactory recoveries ranging from 69.4 to 99.7 %, with relative standard deviations lower than 11.2 %, were obtained for all the compounds. The proposed method is simple, rapid, with low solvent consumption, inexpensive, and environmentally friendly.

Posted in AGL2015-70708-R, Aflatoxins, DLLME, HPLC, P12-AGR-1647, Photo-induced, Yogurt | Tagged , | Comments Off on Determination of aflatoxins in yogurt by dispersive liquid – liquid microextraction and HPLC with photo-induced fluorescence detection.