Search results for "liquid chromatography–mass spectrometry"
showing 10 items of 167 documents
Routine application using single quadrupole liquid chromatography-mass spectrometry to pesticides analysis in citrus fruits.
2005
Abstract A rapid and sensitive liquid chromatography–electrospray ionization–mass spectrometry method has been developed for the routine analysis of buprofezin, bupirimate, hexaflumuron, tebufenpyrad, fluvalinate and pyriproxyfen in citrus fruits. Extracts were obtained by matrix solid-phase dispersion (MSPD) using C 18 as dispersant and dichloromethane-methanol (80:20, v/v) as eluent. Matrix effects were tested for all matrices by addition of standard to sample blank extracts (samples containing no detectable residues). Mean recoveries obtained at fortification levels between 0.01 and 5 mg kg −1 were 57–97% with relative standard deviations (RSDs) from 5 to 19%. The limits of quantificatio…
Comparison of four mass analyzers for determining carbosulfan and its metabolites in citrus by liquid chromatography/mass spectrometry
2006
Four liquid chromatography/mass spectrometry (LC/MS) systems, equipped with single quadrupole, triple quadrupole (QqQ), quadrupole ion trap (QIT) and quadrupole time-of-flight (QqTOF) mass analyzers, were evaluated for the analysis of carbosulfan and its main transformation products. The comparison of quantitative aspects (sensitivity, precision and accuracy) was emphasized. Results showed that the triple quadrupole instrument reaches at least 20-fold higher sensitivity (LOD from 0.04 to 0.4 microg kg(-1)) compared to the single quadrupole (4-70 microg kg(-1)), the QIT (4-25 microg kg(-1)) and the QqTOF (4-23 microg kg(-1)) instruments. Recoveries were over 70% for all the analytes, except …
Rapid whole protein quantitation of staphylococcal enterotoxins A and B by liquid chromatography/mass spectrometry
2012
Abstract Staphylococcus aureus is an important pathogen and has been indicated as the fifth causative agent of food-borne human illness throughout the world. Staphylococcal enterotoxins (SEs) are toxic compounds excreted mainly by strains of S. aureus. Among these toxins, enterotoxins A (SEA) and B (SEB) are both of the most prevalent compounds in staphylococcal food poisoning. In this work, reverse phase liquid chromatography coupled to ESI mass spectrometry (LC–ESI/MS) has been applied for its rapid identification and quantification. Limit of detection (LOD) values were 0.5 and 0.2 ng for SEA and SEB, respectively and limit of quantification (LOQ) value was 1 ng for both enterotoxins. SEA…
Determination of macrolide antibiotics in meat and fish using pressurized liquid extraction and liquid chromatography–mass spectrometry
2008
We developed a method for determining the quantities of seven macrolide antibiotics in meat and fish by using pressurized liquid extraction (PLE) and liquid chromatography-mass spectrometry with electrospray ionization (LC-(ESI)MS). The PLE was optimized with regard to solvents, temperature, pressure, extraction time and number of cycles. The optimum conditions were: methanol as the extraction solvent; a temperature of 80 degrees C; a pressure of 1500psi; an extraction time of 15min; 2 cycles; a flush volume of 150% and a purge time of 300s. All recoveries for macrolide antibiotics were over 77% at 200mug/kg, except for erythromycin, which was 58%. The repeatability and reproducibility on d…
Fragmentation Pathways of Polycyclic Polyisoprenylated Benzophenones and Degradation Profile of Nemorosone by Multiple-Stage Tandem Mass Spectrometry
2009
Nemorosone is a polycyclic polyisoprenylated benzophenone (PPBs) with strong cytotoxic activity. It is the major constituent of Clusia rosea floral resin and brown Cuban propolis. Other PPBs found in Cuban propolis are oxidized and cyclized derivatives of nemorosone. The instability of PPBs carrying an enolizable 1,3-diketone system has been suggested, and the elucidation of this aspect is very fundamental for the evaluation of their biologic activity. Electrospray ionization multistage tandem mass spectrometry (ESI-MSn) was employed to shed light on the origin of these derivatives of nemorosone and to define the stability of this natural product. For this purpose, we initially performed MS…
Estimation of alcohol consumption during >Fallas> festivity in the wastewater of Valencia city (Spain) using ethyl sulfate as a biomarker
2016
Alcohol consumption has been increasing in the last years and it has become a sociological problem due its derived health and safety problems. Ethyl sulfate is a secondary metabolite of the alcohol degradation that is excreted through the urine (0.010-0.016%) after alcohol ingestion and it is quite stable in water. In this study, a new methodology to determine ethyl sulfate by ion-pair liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed. Different ion-pairs and additives were tested directly in the sample extracts or in the mobile phase. The best ion-pair was set up adding 0.5M of tributylamine and 0.1% of formic acid to the sample. The limit of quantification was 0.3μgL…
Antibacterial effect of the bioactive compound beauvericin produced by Fusarium proliferatum on solid medium of wheat.
2010
To obtain the bioactive compound beauvericin (BEA), Fusarium proliferatum CECT 20569 was grown on a solid medium of wheat, utilizing the technique of the solid state fermentation (SSF), being this mycotoxin purified by high performance liquid chromatography (HPLC) with a reverse phase semi-preparative column using as the mobile phase acetonitrile/water in gradient condition. The purity of the BEA was verified by analytical HPLC and liquid chromatography tandem mass spectrometry (LC/MS-MS). The pure fractions of BEA were utilized to determinate the antibiotic effects on several bacterial strains that are considered normally pathogens of the intestinal tract as: Escherichia coli, Enterococcus…
Determination of acrylamide in foods by pressurized fluid extraction and liquid chromatography-tandem mass spectrometry used for a survey of Spanish …
2006
An automated and rapid method for the determination of acrylamide in different food products is presented. The method involves pressurized fluid extraction (PFE) of foods with acetonitrile and precipitation with Carrez reagents. The final extract is analysed by liquid chromatography coupled to electrospray ionization tandem mass spectrometry (ESI-MS-MS). The main parameters affecting the performance of ESI-MS-MS and PFE were optimized using a design of experiments approach. The limit of quantification of the method was 5 microg kg(-1), and recoveries from incurred samples ranged between 93 and 101%. The accuracy was evaluated using the reference test materials FAPAS T3002, T3005 and T3011. …
Metabolomics analysis and biological investigation of three Malvaceae plants
2019
Introduction: Metabolomics is a fast growing technology that has effectively contributed to many plant-related sciences and drug discovery. Objective: To use the non-targeted metabolomics approach to investigate the chemical profiles of three Malvaceae plants, namely Hibiscus mutabilis L. (Changing rose), H. schizopetalus (Dyer) Hook.f. (Coral Hibiscus), and Malvaviscus arboreus Cav. (Sleeping Hibiscus), along with evaluating their antioxidant and anti-infective potential. Methodology: Metabolic profiling was carried out using liquid chromatography coupled with high-resolution electrospray ionisation mass spectrometry (LC-HR-ESI-MS) for dereplication purposes. The chemical composition of th…
Pressurized liquid extraction followed by liquid chromatography–mass spectrometry for determination of zearalenone in cereal flours
2010
Abstract A method for determination of zearalenone in cereal flour has been developed applying pressurized liquid extraction (PLE) using methanol/acetonitrile (50:50 v/v) as the extraction solvent. The extracted samples were analyzed with liquid chromatography coupled to mass spectrometry (LC–MS) with an electro spray ionisation interface (ESI). The method was validated as a quantitative confirmatory method according to the Eu Commission Decision 2002/657/EC. Recoveries of the extraction step data were satisfactory with values higher then 70%. Quantification limits (LOQ) were 5 μg/kg for ESI (+) and 1 μg/kg for ESI (−). Twenty one flour samples produced in different countries were extracted…