Simple determination of aflatoxins in rice by ultra-high performance liquid chromatography coupled to chemical post-column derivatization and fluorescence detection

Posted on 6 November, 2017 by fqm302

A fast and simple analytical method was developed and characterized for the determination of aflatoxins (B1, B2, G1 and G2) in rice. The procedure is based on a simple solid-liquid extraction without further clean-up, and analysis by ultra-high performance liquid chromatography coupled with fluorescence detection. Fluorescence emission of aflatoxins B1 and G1 was enhanced by post-column chemical derivatization using pyridinium bromide perbromide. The analytical method was satisfactorily characterized in white and brown rice. Under optimum conditions, external calibration in solvent could be used for quantification purposes and limits of quantification were below the maximum contents established by the European Union regulation for these contaminants/commodity group combination (0.07–0.14 µg/kg for white rice and 0.20–0.28 µg/kg for brown rice). Recovery studies carried out at three different concentration levels (0.5, 2 and 5 µg/kg) showed values in the range of 84.5–105.3%, and RSDs ≤ 5%.

Posted in AGL2015-70708-R, Aflatoxins, Fluorescence, Rice, Solid-liquid extraction, UHPLC | Tagged , | Comments Off on Simple determination of aflatoxins in rice by ultra-high performance liquid chromatography coupled to chemical post-column derivatization and fluorescence detection

Fully compatible and ultra-sensitive micellar electrokinetic chromatography-tandem mass spectrometry using sheathless porous-tip interfacing.

Posted on 27 October, 2017 by fqm302

The on-line coupling of micellar electrokinetic chromatography and mass spectrometry (MEKC-MS) is often hampered by incompatibility problems leading to reduced separation performance and unfavorable limits of detection (LODs). Here we propose a new selective and highly sensitive MEKC-MS/MS method employing a sheathless porous-tip interface in combination with a micellar phase comprised of semi-volatile surfactant molecules. Carbamate pesticides (CRBs) were selected as representative model compounds being neutral toxic pollutants potentially present at trace levels in environmental water samples. A background electrolyte of 75 mM perfluorooctanoic acid adjusted to pH 9.0 with ammonium hydroxide allowed efficient separation of 15 CRBs and appeared fully compatible with electrospray ionization (ESI)-MS. Interfacing parameters, such as the distance between the capillary tip and mass-spectrometer inlet, ESI voltage, and dry gas temperature and flow were optimized in order to attain good spray stability and high analyte signal-to-noise ratios. For CRBs the LODs ranged from 0.2 to 3.9 ng L−1 (13 nL injected, i.e., 2% of capillary volume), representing an improvement for certain CRBs of more than 300-fold when compared with conventional sheath-liquid interfacing. Good linearity (R2 > 0.99) and satisfactory reproducibility were obtained for all CRBs with interday RSD values for peak area and migration time of 4.0–11.3% and below 1.5%, respectively. Analysis of spiked mineral water showed that the new MEKC-MS/MS method allows selective and quantitative determination of CRB concentrations below the maximum residue limit of 100 ng L−1 without the need for sample preconcentration.

Posted in Carbamates, MEKC, Mass spectrometry, Water | Tagged , | Comments Off on Fully compatible and ultra-sensitive micellar electrokinetic chromatography-tandem mass spectrometry using sheathless porous-tip interfacing.

A high-throughput UHPLC method for the analysis of 5-nitroimidazole residues in milk based on salting-out assisted liquid–liquid extraction.

Posted on 26 October, 2017 by fqm302

A novel salting-out assisted liquid–liquid extraction (SALLE) method has been developed for the extraction of eight 5-NDZ antibiotics from milk samples prior to their analysis by UHPLC. An exhaustive study of the parameters involved in the SALLE procedure has been carried out, optimizing the extraction solvent volume, the amount of the salt agent, and the centrifugation and vortex timing by an experimental design. After sample treatment, the obtained extract was reconstituted in the mobile phase (6:94 (v/v) acetonitrile/water containing 0.1% (v/v) of formic acid) and analyzed by the proposed UHPLC-UV method. Separation was accomplished in a C18 Zorbax Eclipse Plus (50 mm × 2.1 mm, 1.8 μm) column at 45 °C within 8 min. Gradient mode was considered using a mobile phase consisting of 0.1% (v/v) formic acid aqueous solution and acetonitrile containing 0.1% (v/v) formic acid at a flow rate of 0.45 mL/min. Analytical signals were monitored at 320 nm. Matrix-matched calibration curves showed satisfactory linearity (R2 ≥ 0.996). LODs, ranging from 2 to 4 μg/L, were achieved and precision studies showed RSDs lower than 12.8% in terms of peak height. Additionally, recoveries higher than 62.8% were obtained for all studied compounds in milk samples.

Posted in 5-nitroimidazoles, Milk, P12-AGR-1647, SALLE, UHPLC, UV-vis | Tagged , , | Comments Off on A high-throughput UHPLC method for the analysis of 5-nitroimidazole residues in milk based on salting-out assisted liquid–liquid extraction.

Coupling sweeping-micellar electrokinetic chromatography with tandem mass spectrometry for the therapeutic monitoring of benzimidazoles in animal urine by dilute and shoot.

Posted on 2 August, 2017 by fqm302

A new method based on micellar electrokinetic chromatography-tandem mass spectrometry (MEKC-MS/MS) has been developed for the identification and simultaneous quantification of thirteen benzimidazoles in animal urine. In order to obtain an appropriate separation with the highest sensitivity, different electrophoretic parameters were evaluated. Under optimum conditions, the separation was performed using ammonium perfluorooctanoate as volatile surfactant and electrophoretic buffer (50 mM, pH 9). To increase the sensitivity, a stacking mode named sweeping was applied, using water as injection solvent at 50 mbar for 75 s, obtaining sensitivity enhancement factors from 50 to 181. The method was applied to different animal urine samples, including sheep, cow and goat. The sample treatment consisted of a 1:10 (v/v) dilution with water. Calibration using sheep urine samples can be used for both goat and cow urine samples with a relative bias below 25% and relative standard deviations lower than 8%. The limits of detection were below 70 µg L−1. As a result, the applicability of this rapid, simple, sensitive, and environmentally friendly method for therapeutic drug monitoring of benzimidazoles based on the analysis of animal urine has been demonstrated.

Posted in Anthelmintic, Benzimidazoles, Biological fluids, Dilute and shoot, Electrophoresis, MEKC, Mass spectrometry, P12-AGR-1647, Sweeping, Urine | Tagged , , | Comments Off on Coupling sweeping-micellar electrokinetic chromatography with tandem mass spectrometry for the therapeutic monitoring of benzimidazoles in animal urine by dilute and shoot.

Characterization of carbamate pesticides in natural water from Cameroon.

Posted on 19 July, 2017 by fqm302

With the increased use of chemicals in agriculture for crop protection and improvement of yield, the contamination of water is currently a serious health concern. This study used solid-phase extraction with ultra-high-performance liquid chromatography–tandem mass spectrometry to evaluate the presence of 23 carbamate pesticides in waters from Cameroon. The separation was achieved in 5.5 min using a C18 column (50 × 2.1 mm, 1.8 µm) with a mobile phase composed of water and methanol each containing 0.01% formic acid. The analytes were determined in positive multiple reaction monitoring mode. The recoveries for fortified water were from 75 to 99%, with relative standard deviations below 13%. The limits of detection ranged from 0.003 to 0.397 µg L−1. The reported method is simple, sensitive, and accurate, and is a suitable alternative for routine monitoring of pesticide residues at ultra-trace levels. The analysis revealed the presence of propoxur at a concentration of 0.072 µg L−1 in stream water.

Posted in Carbamates, Mass spectrometry, P12-AGR-1647, Pesticides, SPE, UHPLC, Water | Tagged , , | Comments Off on Characterization of carbamate pesticides in natural water from Cameroon.

Evaluation of hydrophilic interaction liquid chromatography–tandem mass spectrometry and extraction with molecularly imprinted polymers for determination of aminoglycosides in milk and milk-based functional foods.

Posted on 10 July, 2017 by fqm302

An analytical method for the determination of eleven aminoglycosides in different types of milk and milk-based functional products has been optimized and validated. A hydrophilic interaction chromatography (HILIC) column was proposed for the separation of analytes by ultra-high performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS). A commercially molecularly imprinted polymer has been used for the solid phase extraction of the analytes, in order to achieve high selectivity in the sample treatment. The proposed method was characterized for different types of milk (whole cow milk, skimmed cow milk, whole goat milk) and functional dairy products, such as follow-on milk, Omega 3-enriched milk and isoflavones-enriched milk. Matrix effect was studied in the different matrices, being lower than │15│% in all cases, showing that the proposed procedure provided very clean extracts. Limits of quantification in the range 4.2–49 µg kg−1 were estimated, well below the maximum residue limits established by the European Union. Recoveries ranged from 70% to 106% with RSD lower than 13%, in compliance with the current legislation. The combination of HILIC to solve the difficulties of the separation of these very polar compounds in reverse phase with the use of MISPE for sample treatment and MS/MS detection provided a very sensitive, highly selective, robust and useful method for identification and quantification of aminoglycoside residues in different types of milk and milk-based products.

Posted in AGL2015-70708-R, Aminoglycosides, HILIC, MIPs, Mass spectrometry, Milk, P12-AGR-1647 | Tagged , , | Comments Off on Evaluation of hydrophilic interaction liquid chromatography–tandem mass spectrometry and extraction with molecularly imprinted polymers for determination of aminoglycosides in milk and milk-based functional foods.

Evaluation of a multiresidue capillary electrophoresis-quadrupole-time-of-flight mass spectrometry method for the determination of antibiotics in milk samples.

Posted on 7 July, 2017 by fqm302

A selective and rapid method has been developed to determine 15 antibiotic residues (eight tetracyclines and seven quinolones) in milk samples by capillary zone electrophoresis coupled with quadrupole time-of-flight mass spectrometry (CZE-Q-TOF-MS). The use of this hybrid mass spectrometer allowed obtaining full scan and full MS/MS spectra for quantification/confirmation purposes in a single run. In addition, solid phase extraction (SPE) using the new Oasis PRiME HLB cartridge was proposed for the extraction, achieving excellent results in terms of sample throughput. The proposed method was validated using whole cow milk as representative matrix. Good linearity was obtained (R2 > 0.99) for all the studied compounds. The precision, expressed as relative standard deviation (%, RSD), at two concentration levels (50 and 100 μg kg−1) was below 13%. Recoveries obtained from goat milk, whole cow milk and semi-skimmed cow milk, at two concentration levels, ranged from 76 to 106%, while limits of quantification ranged from 1.5 to 9.6 μg kg−1, being lower than the established maximum residue limits in the European legislation. Matrix effect was negligible in all cases, showing that with this new SPE sorbent cleanest extracts were obtained with a minimum number of steps in the sample treatment. Thus, the proposed SPE-CZE-Q-TOF-MS method is suitable for multiclass multiresidue monitoring in different types of milk samples.

Posted in Antibiotics, CZE, Food, Mass spectrometry, Milk, P12-AGR-1647, Quinolones, SPE, Tetracyclines | Tagged , , | Comments Off on Evaluation of a multiresidue capillary electrophoresis-quadrupole-time-of-flight mass spectrometry method for the determination of antibiotics in milk samples.

Evaluation of a multiresidue capillary electrophoresis-quadrupole-time-of-flight mass spectrometry method for the determination of antibiotics in milk samples.

Posted on 19 June, 2017 by fqm302

A selective and rapid method has been developed to determine 15 antibiotic residues (eight tetracyclines and seven quinolones) in milk samples by capillary zone electrophoresis coupled with quadrupole time-of-flight mass spectrometry (CZE-Q-TOF-MS). The use of this hybrid mass spectrometer allowed obtaining full scan and full MS/MS spectra for quantification/confirmation purposes in a single run. In addition, solid phase extraction (SPE) using the new Oasis PRiME HLB cartridge was proposed for the extraction, achieving excellent results in terms of sample throughput. The proposed method was validated using whole cow milk as representative matrix. Good linearity was obtained (R2 > 0.99) for all the studied compounds. The precision, expressed as relative standard deviation (%, RSD), at two concentration levels (50 and 100 μg kg−1) was below 13%. Recoveries obtained from goat milk, whole cow milk and semi-skimmed cow milk, at two concentration levels, ranged from 76 to 106%, while limits of quantification ranged from 1.5 to 9.6 μg kg−1, being lower than the established maximum residue limits in the European legislation. Matrix effect was negligible in all cases, showing that with this new SPE sorbent cleanest extracts were obtained with a minimum number of steps in the sample treatment. Thus, the proposed SPE-CZE-Q-TOF-MS method is suitable for multiclass multiresidue monitoring in different types of milk samples.

Posted in Antibiotics, CZE, Mass spectrometry, Milk, P12-AGR-1647, Quinolones, SPE, Tetracyclines | Tagged , , | Comments Off on Evaluation of a multiresidue capillary electrophoresis-quadrupole-time-of-flight mass spectrometry method for the determination of antibiotics in milk samples.

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