QuEChERS-based method for the determination of carbamate residues in aromatic herbs by UHPLC-MS/MS

Posted on 16 September, 2016 by fqm302

A new reliable, fast and highly sensitive method based on ultra-high performance liquid chromatography tandem mass spectrometry has been developed and validated for the determination of 28 carbamates in aromatic herbs. A modified QuEChERS-based method was optimized for the extraction of carbamate residues from a wide variety of fresh herbal products. The proposed method allowed recoveries higher than 72%, achieving quantification limits of 2 μg kg−1, therefore below maximum residue limits established for this type of samples. The combination of QuEChERS with UHPLC-MS/MS introduces a high-throughput methodology for the monitoring of these residues in this type of matrices scarcely explored. The analysis of the real samples revealed that several samples sold in the European Union and in the North West region of Cameroon contain pesticides in concentrations below the maximum residue limits.

Posted in AGL2015-70708-R, Aromatic herbs, Carbamates, Mass spectrometry, QuEChERS, UHPLC | Tagged | Comments Off on QuEChERS-based method for the determination of carbamate residues in aromatic herbs by UHPLC-MS/MS

Capillary electrochromatography coupled with dispersive liquid-liquid microextraction for the analysis of benzimidazole residues in water samples

Posted on 12 August, 2016 by fqm302

A novel method for the analysis of benzimidazole residues in water samples by capillary electrochromatography-UV detection (290 nm), using laboratory-made packed columns is presented. Capillaries (25 cm packed length×75 µm inner diameter, 34 cm total length, 25.5 cm effective capillary length) were packed with C18 particles (5 µm, non-encapped) following a high pressure packing procedure and using a compact steel unit designed for packing capillary columns. Acetone was employed as solvent to carry the particles through the capillary and pack it under a pressure of 42 MPa. Outlet and inlet frits were made by sintering the particles of the stationary phase by heating the packed material with a nichrome ribbon connected to a 7 V AC power supply. With the aim of achieving a good analytical performance, the variables that affected the separation were studied, using a mobile phase composition of 60:40 (v/v) acetonitrile/water containing ammonium acetate (1 mM, pH 6.5), a separation voltage of 25 kV and a temperature of 25 °C. In addition, a combined hydrodynamic-electrokinetic injection mode was considered and samples were injected for 75 s under a voltage of 12.5 kV and a pressure of 11.5 bar. Finally, the determination of benzimidazoles in water samples was accomplished by capillary electrochromatography using dispersive liquid-liquid microextraction as sample treatment. Variables affecting the extraction efficiency were optimized, using chloroform and ethanol as extraction and disperser solvents, respectively.

This method was applied to different water samples, obtaining satisfactory results in terms of linearity (R2≥0.990), repeatability (RSD≤1.2%), reproducibility (RSD≤2.2%) and trueness (R≥87.7%). Detection and quantification limits were lower than 2.8 µg L−1 and 9.3 µg L−1, respectively.

Posted in Anthelmintic, Benzimidazoles, DLLME, Electrochromatography, P12-AGR-1647, Projects, UV-vis, Water | Tagged , | Comments Off on Capillary electrochromatography coupled with dispersive liquid-liquid microextraction for the analysis of benzimidazole residues in water samples

Evaluation of the combination of micellar electrokinetic capillary chromatography with sweeping and cation selective exhaustive injection for the determination of 5-nitroimidazoles in egg samples

Posted on 27 July, 2016 by fqm302

A methodology is presented for the sensitive determination of nitromidazole residues in egg by means of micellar electrokinetic capillary chromatography in combination with cation selective exhaustive injection and ultraviolet detection. Six compounds have been considered and the separation has been achieved in less than 12 min in a 61.5-cm effective length capillary with 50-μm internal diameter. Phosphate buffer 44 mM pH 2.5, containing 8% tetrahydrofurane and 123 mM sodium dodecyl sulfate was employed as running buffer. Solid phase extraction has been employed for sample clean-up. The methodology has been successfully validated in hen eggs, obtaining method detection limits in the range of 2.1–5.0 ng/g. Precision was studied in terms of repeatability and intermediate precision, with relative standard deviations lower than 18.0%. Recoveries were calculated in quail eggs and a commercial pasteurized egg white product, reaching over 70% for most of the considered 5-nitroimidazoles.

Posted in 5-nitroimidazoles, CSEI, Eggs, MEKC, P12-AGR-1647, SPE, Sweeping, UV-vis | Tagged , | Comments Off on Evaluation of the combination of micellar electrokinetic capillary chromatography with sweeping and cation selective exhaustive injection for the determination of 5-nitroimidazoles in egg samples

Rapid and simple UHPLC-ESI-MS/MS method for the screening of propyl propane thiosulfonate, a new additive for animal feed

Posted on 4 July, 2016 by fqm302

Allium derivative propyl propane thiosulfonate (PTSO) is a new additive for animal feed which improves animal health when used as an alternative to antibiotic growth promoters. Despite the effort of the European Union to ensure the control of animal feed alterations, information available on this new additive is sparse and analytical methods used for its monitoring have limited reach. Moreover, existing analytical methods exhibit shortcomings when applied to other matrices or when attempting to measure low concentration levels. This paper describes for the first time that PTSO reacts instantaneously with cysteine (CYS) and glutathione (GLU) generating s-propyl mercaptocysteine (CSSP) and s-propyl mercaptoglutathione (GSSP), thus explaining the limitations of previous methods when applied to feed with high concentration levels of CYS and GLU. Therefore, an ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method combined with a sample treatment based on simple solid–liquid extraction with methanol is proposed for the monitoring of PTSO, CSSP and GSSP in a wide range of animal feed samples including those for pigs, piglets, broilers, hens, rabbits and partridges. This method provides a simple, robust and efficient alternative for the determination of this additive. Matrix-matched calibration curves were established for PTSO, CSSP and GSSP and limits of detection (LODs) and quantification (LOQs) were estimated, being lower than the ones previously reported for PTSO when using HPLC-UV. The relative standard deviation of the whole analytical method was lower than 10% in all cases, while recoveries ranged from 93% to 104%.

Posted in Animal feed, Mass spectrometry, PTSO, UHPLC | Tagged | Comments Off on Rapid and simple UHPLC-ESI-MS/MS method for the screening of propyl propane thiosulfonate, a new additive for animal feed

Trace determination of tetracyclines in water samples by capillary zone electrophoresis combining off-line and on-line sample preconcentration

Posted on 3 May, 2016 by fqm302

In this work, a sensitive and reliable method using capillary zone electrophoresis with UV detection has been developed for trace determination of tetracycline antibiotics in river, spring, and ground waters. A solid-phase extraction method using Oasis HLB was applied for off-line preconcentration and cleanup of water samples, in combination with an on-line preconcentration methodology named large volume sample stacking with polarity switching. Different parameters were optimized in order to obtain an adequate separation combined with the highest sensitivity, using 75 mM sodium carbonate (pH 10) and 1 mM EDTA as separation buffer, applying a voltage of 25 kV at 25°C. The samples were injected in water at 1 bar for 1 min, applying then −25 kV and starting the sample stacking. Sample matrix removal from the capillary was controlled by monitoring the electric current (when the 95% of the separation current is reached the stacking process is completed). The applied voltage was then switched from negative to a positive value of 25 kV in order to separate the compounds. Under optimum conditions, sensitivity enhancement factors ranged from 303 to 428 for the studied compounds. The combination of both off-line and on-line preconcentration procedures provided a total sensitivity enhancement factor about 20 000, obtaining detection limits from 67 to 167 ng/L. The precision (intra- and interday), expressed as %RSD was below 12%. Recoveries obtained from river, spring, and ground waters ranged from 87 to 96%. Thus, this procedure is suitable for monitoring these compounds in water samples.

Posted in CZE, LVSS, P12-AGR-1647, SPE, Tetracyclines, UV-vis, Water | Tagged , | Comments Off on Trace determination of tetracyclines in water samples by capillary zone electrophoresis combining off-line and on-line sample preconcentration

Method optimization and validation for the determination of eight sulfonamides in chicken muscle and eggs by modified QuEChERS and liquid chromatography with fluorescence detection

Posted on 10 March, 2016 by fqm302

A simple, effective and reliable method for the determination of eight sulfonamide antibiotics (sulfadiazine, sulfapiridine, sulfamerazine, sulfamethazine, sulfachloropiridazine, sulfamethoxazole, sulfadoxine, sulfadimethoxin) in chicken muscle and eggs by liquid chromatography and fluorescence detection has been developed and validated. Sulfonamides do not present native fluorescence, however their direct determination was achieved by on-line post-column photochemical derivatization by UV irradiation. Sample treatment was based on QuEChERS with several modifications depending on the matrix. Egg extracts were cleaned-up using PSA for the dispersive solid phase extraction step. On the other hand, a new clean-up sorbent, Supel™ QuE Z-Sep+, has been successfully applied in chicken muscle extract and has proved to be effective for interference removal from this matrix. Under optimum conditions, recoveries from 65.9 to 88.1%, relative standard deviations lower than 10% (except for sulfachloropiridazine), and limits of quantification (LOQs) from 14 to 85 μg kg−1 were achieved. Thus, the method complies with current European requirements.

Posted in Chicken muscle, Eggs, Fluorescence, P12-AGR-1647, QuEChERS, Sulfonamides | Tagged | Comments Off on Method optimization and validation for the determination of eight sulfonamides in chicken muscle and eggs by modified QuEChERS and liquid chromatography with fluorescence detection

Applications of capillary electrophoresis with chemiluminescence detection in clinical, environmental and food analysis. A review.

Posted on 1 February, 2016 by fqm302

This paper reviews the latest developments and analytical applications of chemiluminescence detection coupled to capillary electrophoresis (CE-CL). Different sections considering the most common CL systems have been included, such as the tris(2,2ʹ-bipyridine)ruthenium(II) system, the luminol and acridinium derivative reactions, the peroxyoxalate CL or direct oxidations. Improvements in instrumental designs, new strategies for improving both resolution and sensitivity, and applications in different fields such as clinical, pharmaceutical, environmental and food analysis have been included. This review covers the literature from 2010 to 2015.

Posted in Chemiluminescence, Electrophoresis, P12-AGR-1647, Review | Tagged , , | Comments Off on Applications of capillary electrophoresis with chemiluminescence detection in clinical, environmental and food analysis. A review.

Development of a QuEChERS-based extraction method for the determination of destruxins in potato plants by UHPLC–MS/MS

Posted on 15 December, 2015 by fqm302

Ultra high performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS) with electrospray ionization has been proposed for the determination of fifteen natural destruxins (A, B, C, D, E, Ed, Ed1, A2, B2, D2, E2, Cl, DesmA, DesmB, and DH-A), secondary metabolites with insecticidal and phytotoxic activities produced by Metarhizium species fungus, which are being studied as biological agents in pest control. Therefore, procedures to control them in the food chain are required, starting with crops. As a consequence, in this study, a simple QuEChERS-based destruxin (dtx) extraction procedure has been developed and validated in four different parts of potato plant (tuber, root, stem and leaves) for the first time. For dtx A, the limits of detection obtained, ranged between 0.5 and 1.3 μg/kg, and for quantification, ranged between 1.7 and 4.2 μg/kg. Precision values were below 8.5%; and in all cases, recoveries were higher than 91%. Finally, the method has been applied in potato samples inoculated by EAMa 01/58-Su strain, where dtxs A and B were detected and quantified. In all cases, dtx B concentration was higher than dtx A.

Posted in Destruxins, Mass spectrometry, Metabolites, Mycotoxins, Plants, Potato plant, QuEChERS, UHPLC | Tagged | Comments Off on Development of a QuEChERS-based extraction method for the determination of destruxins in potato plants by UHPLC–MS/MS

On-line preconcentration strategy for the simultaneous quantification of three local anaesthetics in human urine using capillary zone electrophoresis

Posted on 15 December, 2015 by fqm302

The simultaneous determination of usually employed anaesthetics (procaine, lidocaine and bupivacaine) has been developed and validated using capillary electrophoresis with ultraviolet detection at 212 nm. The separation of these three drugs has been achieved in less than 7 min, using a temperature of 25º C and 25 kV, with a 150 mM citrate buffer (pH 2.5) as background electrolyte. Field amplified sample injection (FASI) has been used for on-line sample preconcentration. Ultrapure water and acetonitrile 50/50 (v/v) mixture gave the greatest enhancement factor when it was employed as injection solvent. Injection voltage and time were optimized, being 13 kV and 13 s, the optimum values respectively. To avoid the possible irreproducibility associated with the electrokinetic injection, an internal standard such as tetracaine, was employed. The instrumental detection limits (LOD s/n = 3) for the compounds ranged between 2.6 and 7.0 μg L−1 and the quantitation limits (LOQ s/n = 10) between 37.8 and 55.9 μg L−1. The detection limits obtained in real human urine samples ranged between 55.2 and 83.6 μg L−1 and the quantitation limits between 196.0 and 276.0 μg L−1. The proposed method has demonstrated its applicability to the analysis of these local anaesthetics in urine samples without any pretreatment, allowing the rapid determination of these target analytes.

Posted in Anaesthetics, CZE, FASI, UV-vis, Urine | Comments Off on On-line preconcentration strategy for the simultaneous quantification of three local anaesthetics in human urine using capillary zone electrophoresis

Advances in the application of chemiluminescence detection in liquid chromatography

Posted on 21 November, 2015 by fqm302

Recently, chemiluminescence (CL)-based detection has become a very useful detection system in high-performance liquid chromatography (HPLC) due to its simplicity, low cost, high sensitivity and high selectivity. Some methods such as the use of photochemically induced CL reactions, the application of nanoparticles and new sample treatments have been combined either with well-known CL reactions based on the use of luminol, tris(2,2-bipyridine) ruthenium (II) and peroxyoxalate as CL precursors or with direct oxidations. This review presents some important contributions published during the last 5 years.

Posted in Chemiluminescence, P12-AGR-1647, Review | Tagged | Comments Off on Advances in the application of chemiluminescence detection in liquid chromatography