Amino‐functionalized material from a bio‐template for silver adsorption: process evaluation in batch and fixed bed

Posted on 15 October, 2018 by fqm302

The modification of an organic matrix as a bio‐template (grapefruit peel) using urea and melamine was carried out to introduce amino groups on its surface and favor Ag(I) adsorption in aqueous solution for metal recovery. Adsorption capacity in batch mode was proportional to the nitrogen content within the adsorbents, the maximum being the one obtained with the adsorbent functionalized with urea, 72.33 mg g−1, which was tested as a fixed bed in a column to evaluate the metal adsorption in a continuous flow model. The adsorption capacity of the fixed bed was 15.14 mg g−1, and its use was proved over three adsorption–desorption cycles. Amino‐functionalized adsorbent achieved a high Ag+ uptake capacity; from the characterization it is proposed that the adsorption mechanism consists in the formation of the complex R‐NH2Ag+ and R‐COOAg.

Posted in Wastewater | Comments Off on Amino‐functionalized material from a bio‐template for silver adsorption: process evaluation in batch and fixed bed

Effects of different vehiculization strategies for the allium derivative propyl propane thiosulfonate during dynamic simulation of the pig gastrointestinal tract.

Posted on 26 September, 2018 by fqm302

This paper evaluates the bioavailability of allium derivative propyl propane thiosulfonate (PTSO) in the pig gastrointestinal tract by means of an in vitro dynamic gastrointestinal tract simulator system (GITSS). The GITSS is based on a membrane bioreactor comprising a continuous stirred-tank reactor connected in series to a continuous plug-flow tubular reactor. Bioavailability values have been evaluated for different vehiculization strategies, including mere carriers such as polyethylene glycol sorbitan monooleate (a nonionic surfactant also known as Tween 80) and encapsulation matrices (β-cyclodextrin vs. mono- and di-glycerides of edible fatty acids mixed with hydrogenated sunflower oil) and compared with the absorption of free PTSO. The net absorbed amount of PTSO in the GITSS when Tween 80 was used as a carrier was over 3.5 times higher than the one for free PTSO. Neither the encapsulated PTSO in β-cyclodextrin nor by means of mono- and di-glycerides of fatty acids plus a vegetable oil succeeded to improve absorption values for free PTSO. These promising results indicate that Tween 80 provides an interesting and high resistance to the PTSO molecule against the simulated digestive conditions in the stomach, and thus it enables favorably the subsequent absorption process of PTSO along the intestine.

Posted in Animal feed, PTSO | Comments Off on Effects of different vehiculization strategies for the allium derivative propyl propane thiosulfonate during dynamic simulation of the pig gastrointestinal tract.

Aspergillus section Flavi and aflatoxins in dried figs and nuts in Algeria

Posted on 18 June, 2018 by fqm302

The presence of Aspergillus section Flavi and aflatoxin (AF) contamination was investigated in 112 samples of peanuts, almonds and dried figs collected in Algeria. The occurrence of aflatoxin B1 (AFB1), B2 (AFB2), G1 (AFG1) and G2 (AFG2) in different commodities has been determined with a sensitive method based on high performance liquid chromatography (HPLC) coupled with fluorescence detection with post-column photochemical derivatisation. Analytical results indicated that 28 samples of peanuts, 16 samples of almonds and 26 samples of dried figs contained detectable levels of AFs. A total of 69 samples (61.6%) were contaminated with AFB1 ranging from the limit of quantification to 174 µg kg−1. AFB2 was found in 12 samples (10.7%) and varied from 0.18 to 193 µg kg−1. Seven samples revealed AF concentrations lower than the limit of quantification. Eleven peanut and fourteen dried fig samples exceeded the European maximum limits for AFB1.

Posted in AGL2015-70708-R, Aflatoxins, Dried fruit, HPLC, Mycotoxins, Nuts, Photo-induced, Solid-liquid extraction | Tagged , | Comments Off on Aspergillus section Flavi and aflatoxins in dried figs and nuts in Algeria

Development and validation of a QuEChERS method for the analysis of 5-nitroimidazole traces in infant milk-based samples by ultra-high performance liquid chromatography-tandem mass spectrometry

Posted on 14 June, 2018 by fqm302

QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) methodology in combination with UHPLC–MS/MS is proposed for the determination of 5-nitroimidazole (5-NDZ) residues in infant milk-based products. Chromatographic separation was accomplished in a C18 Zorbax Eclipse Plus RRHD (50 × 2.1 mm, 1.8 μm) column under gradient elution conditions. Mobile phase consisted of 0.025% (v/v) aqueous formic acid (eluent A) and MeOH (eluent B), and was supplied at a flow rate of 0.5 mL/min. Under these conditions, eleven 5-NDZs including three metabolites were separated in less than 4 min. A novel QuEChERS method was optimized, and primary-secondary amine (PSA) sorbent was selected as clean-up agent. In addition, the proposed QuEChERS procedure was compared with other sample preparation methodologies, which are usually used in the analysis of 5-NDZs, namely solid phase extraction (SPE) using mixed cation exchange (MCX) cartridges and molecularly imprinted solid phase extraction (MISPE). Method comparison was carried out in terms of process efficiency, which includes matrix effect and extraction recovery. Higher process efficiency was generally achieved for QuEChERS and MISPE than for SPE. However, matrix effect was more significant for the non-selective QuEChERS method than for the selective MISPE. Higher extraction recoveries (63.2–94.1%) were observed for QuEChERS. The studied methods were validated in terms of linearity, detection limits (CCα), detection capabilities (CCβ) and precision, observing similar performance characteristics independently of the proposed sample treatment. CCα and CCβ ranged between 0.05 and 1.69 μg/L for all analytes and extraction techniques. QuEChERS-UHPLC–MS/MS method was also validated in terms of precision (relative standard deviations <10.3%), trueness (recovery>70.2%) and selectivity according to Regulation 2002/657/EC. It is proposed as a good alternative for the monitoring of 5-NDZ residues in enriched infant-milk based products and other similar milk based-products.

Posted in 5-nitroimidazoles, AGL2015-70708-R, Infant foods, Mass spectrometry, P12-AGR-1647, QuEChERS, UHPLC | Tagged , , | Comments Off on Development and validation of a QuEChERS method for the analysis of 5-nitroimidazole traces in infant milk-based samples by ultra-high performance liquid chromatography-tandem mass spectrometry

Green and simple analytical method to determine benzimidazoles in milk samples by using salting-out assisted liquid-liquid extraction and capillary liquid chromatography

Posted on 29 May, 2018 by fqm302

A green and simple multiresidue method using capillary liquid chromatography (CLC) with UV-diode array detection (DAD) has been developed for the determination of sixteen benzimidazoles (BZs) and its metabolites in milk samples. The separation was achieved in <32 min, using a Zorbax XDB-C18 column (150 mm × 0.5 mm I.D, 5 μm), with a mobile phase consisting of 50 mM ammonium acetate (solvent A) and a mixture of acetonitrile/methanol (1:1 v/v) (solvent B), at a flow rate of 9 μL min−1. The temperature of the column was 20 °C and 6 μL of sample were injected. In spite of the complexity of milk samples, an effective, simple and fast sample preparation method called salting out-assisted liquid-liquid extraction (SALLE) was developed for the analysis of these compounds in cow milk samples. To obtain satisfactory extraction efficiencies for the studied analytes, several parameters affecting the SALLE procedure were optimized including the amount of sample, type and volume of the extraction solvent, and the nature and amount of the salt. Good linearity was obtained (R2 > 0.9985 for all BZs) with limits of detection (LOD) between 1.0 and 2.8 μg kg−1. Relative standard deviations of repeatability and intermediate precision were below 1.6 and 14.2%, respectively. Satisfactory recoveries between 79.1 and 99.6% were also obtained for three types of milk samples (cow, sheep and goat). The advantages of a miniaturized technique such as CLC in terms of better efficiencies and reduced solvent consumption, combined with the simplicity of the SALLE procedure, make this method a useful alternative for the monitoring of these residues at trace level.

Posted in AGL2015-70708-R, Benzimidazoles, Capillary HPLC, Milk, P12-AGR-1647, SALLE, UV-vis | Tagged , , | Comments Off on Green and simple analytical method to determine benzimidazoles in milk samples by using salting-out assisted liquid-liquid extraction and capillary liquid chromatography

Collision cross section (CCS) database: an additional measure to characterize steroids.

Posted on 10 May, 2018 by fqm302

Ion mobility spectrometry enhances the performance characteristics of liquid chromatography–mass spectrometry workflows intended to steroid profiling by providing a new separation dimension and a novel characterization parameter, the so-called collision cross section (CCS). This work proposes the first CCS database for 300 steroids (i.e., endogenous, including phase I and phase II metabolites, and exogenous synthetic compounds), which involves 1080 ions and covers the CCS of 127 androgens, 84 estrogens, 50 corticosteroids, and 39 progestagens. This large database provides information related to all the ionized species identified for each steroid in positive electrospray ionization mode as well as for estrogens in negative ionization mode. CCS values have been measured using nitrogen as drift gas in the ion mobility cell. Generally, direct correlation exists between mass-to-charge ratio (m/z) and CCS because both are related parameters. However, several steroids mainly steroid glucuronides and steroid esters have been characterized as more compact or elongated molecules than expected. In such cases, CCS results in additional relevant information to retention time and mass spectral data for the identification of steroids. Moreover, several isomeric steroid pairs (e.g., 5β-androstane-3,17-dione and 5α-androstane-3,17-dione) have been separated based on their CCS differences. These results indicate that adding the CCS to databases in analytical workflows increases selectivity, thus improving the confidence in steroids analysis. Consequences in terms of identification and quantification are discussed. Quality criteria and a construction of an interlaboratory reproducibility approach are also reported for the obtained CCS values. The CCS database described here is made publicly available.

Posted in Ion mobility, Steroids | Tagged | Comments Off on Collision cross section (CCS) database: an additional measure to characterize steroids.

Optimization of a modified QuEChERS method for the determination of tetracyclines in fish muscle by UHPLC–MS/MS.

Posted on 20 March, 2018 by fqm302

In this work a sample treatment based on a modified QuEChERS method combined with ultra-high-performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS) was proposed to determine the residues of five common tetracyclines in fish muscle samples. The separation was achieved in less than 4 min and the analytes were detected in electrospray ionization in positive mode (ESI+) with multiple reaction monitoring mode. Parameters affecting the extraction step, such as the amount of sample and EDTA-McIlvaine buffer and extraction solvent volumes, were optimized by means of experimental design. In order to obtain the lowest matrix effect, parameters affecting the clean-up step by dispersive solid phase extraction (dSPE), were also studied. Under optimum conditions, matrix effect was lower than │15│% in all cases. Limits of quantification were lower than 4.4 μg kg−1 for the compounds in the selected samples, being in compliance with the current legislation. The precision, expressed as relative standard deviation, was below 18.5% and the recoveries for fortified fish samples (salmon and panga) higher than 80%. These results revealed that the proposed method is simple, rapid, cheap and environmentally friendly, being successfully applicable for the determination of these residues in fish samples.

Posted in Mass spectrometry, Panga, QuEChERS, Salmon, Tetracyclines, UHPLC | Tagged , , | Comments Off on Optimization of a modified QuEChERS method for the determination of tetracyclines in fish muscle by UHPLC–MS/MS.

Ultra-high performance liquid chromatography with fluorescence detection following salting-out assisted liquid–liquid extraction for the analysis of benzimidazole residues in farm fish samples

Posted on 14 March, 2018 by fqm302

Ultra-high performance liquid chromatography (UHPLC) coupled with fluorescence detection (FL) has been proposed for the first time to determine thirteen benzimidazoles (BZs) in farmed fish samples. In order to optimize the chromatographic separation, parameters such as mobile phase composition and flow rate were carefully studied, establishing a gradient mode with a mobile phase consisted of water (solvent A) and acetonitrile (solvent B) at a flow rate of 0.4 mL/min. The separation was performed on a Zorbax Eclipse Plus RRHD C18 column (50 × 2.1 mm, 1.8 μm), involving a total analysis time lower than 12 min. Salting-out assisted liquid-liquid extraction (SALLE) was applied as sample treatment to different types of farmed fish (trout, sea bream and sea bass). To obtain satisfactory extraction efficiencies for the studied analytes, several parameters affecting the SALLE procedure were optimized including the amount of sample, type and volume of the extraction solvent, and the nature and amount of the salt used. Characterization of the method in terms of performance characteristics was carried out, obtaining satisfactory results for the linearity (R2 ≥ 0.997), repeatability (RSD ≤ 6.1%), reproducibility (RSD ≤ 10.8%) and recoveries (R ≥ 79%; RSD ≤ 7.8%). Detection limits between 0.04–29.9 μg kg−1 were obtained, demonstrating the applicability of this fast, simple and environmentally friendly method.

Posted in AGL2015-70708-R, Anthelmintic, Aquaculture products, Benzimidazoles, Fluorescence, P12-AGR-1647, SALLE, Sea bass, Sea bream, Trout, UHPLC | Tagged , , | Comments Off on Ultra-high performance liquid chromatography with fluorescence detection following salting-out assisted liquid–liquid extraction for the analysis of benzimidazole residues in farm fish samples

Simple and rapid determination of 5-nitroimidazoles and metabolites in fish roe samples by salting-out assisted liquid-liquid extraction and UHPLC-MS/MS.

Posted on 23 February, 2018 by fqm302

A novel multiresidue method is proposed for the determination of 12 5-nitroimidazoles and their metabolites in fish roe samples using UHPLC-MS/MS. A salting-out assisted liquid-liquid extraction procedure was performed prior to sample analysis. The separation of compounds was accomplished using a C18 Zorbax Eclipse Plus column (50 mm × 2.1 mm, 1.8 µm) at 25 °C and a mobile phase consisting of 0.025% (v/v) aqueous formic acid and pure MeOH at a flow rate of 0.5 mL/min. Parameters involved in ionization and fragmentation were also optimized. The method was characterized in terms of linearity (R2 ≥ 0.9992), extraction efficiency (≥68.9%), repeatability (RSD ≤ 9.8%), reproducibility (RSD ≤ 13.9%) and trueness (recoveries ≥81.4%). Decision limits (CCα) and detection capabilities (CCβ) were obtained in the ranges 0.1–1.0 and 0.2–1.7 µg/kg, respectively.

Posted in 5-nitroimidazoles, Fish roe, Mass spectrometry, P12-AGR-1647, SALLE, UHPLC | Tagged , , | Comments Off on Simple and rapid determination of 5-nitroimidazoles and metabolites in fish roe samples by salting-out assisted liquid-liquid extraction and UHPLC-MS/MS.

Determination of tetracyclines in human urine samples by capillary electrophoresis in combination with field amplified sample injection.

Posted on 9 November, 2017 by fqm302

A sensitive method using CZE‐UV detection has been developed for the determination of five tetracycline antibiotics in human urine samples. To improve the sensitivity of the method, an on‐line preconcentration strategy, named field‐amplified sample injection, has been developed, based on the electrokinetic injection of the sample, which requires only a 1:100 dilution with sample solvent before injection. Under optimum conditions, sensitivity enhancement factors ranged from 450 to 800 for the studied compounds. The applicability of the proposed method was demonstrated by the determination of these antibiotics in spiked urine samples. The limits of quantification were lower than 0.8 mg/L and the precision (intra‐ and inter‐day), expressed as %RSD was below 14%. Recoveries ranged from 92.1 to 96.7%. Thus, the proposed procedure is a simple, fast and efficient strategy which could be used as therapeutic drug monitoring in human urine samples.

Posted in CZE, Dilute and shoot, FASI, P12-AGR-1647, Tetracyclines, UV-vis, Urine | Tagged , | Comments Off on Determination of tetracyclines in human urine samples by capillary electrophoresis in combination with field amplified sample injection.