1,720,983 research outputs found
Determination of endocrine disrupting compounds in surface waters by means of chromatographic techniques coupled to mass spectrometry
No full textDeterminazione di interferenti endocrini in acque superficiali mediante tecniche cromatografiche accoppiate alla spettrometria di massa
No full textAMMONIUM 5-BROMO-7-FLUOROBENZO-2-OXA-1,3-DIAZOLE-4-SULPHONATE: A NEW FLUOROGENIC REAGENT FOR THE DETERMINATION OF AMINOTHIOLS BY HPLC
No full textThe new fluorogenic derivatization reagent SBD-BF reacts with biological thiols (e.g., homocysteine, cysteine, glutathione etc.) under very mild conditions and in a reduced period of time (15 min), thus allowing their fast, precise and inexpensive assessment in the biological fluids
Determination of endocrine disrupting compounds in drinking waters by fast liquid chromatography-tandem mass spectrometry
No full textGrowing attention has been recently paid to safety of food and drinking water, making necessary the adoption of policies for water sources protection and the development of sensitive and rapid analytical methods to identify micropollutants.
Endocrine-disrupting compounds (EDCs) have emerged as amajor issue as they alter the functioning of the endocrine system. Since ingestion of EDCs via food is considered themajor exposure route, there is a growing interest in understanding EDC fate during drinking water treatment and inmonitoring potential contamination of surface waters and groundwaters. In this work, a fast liquid chromatography–electrospray ionization–tandemmass spectrometrymethodwas developed for the determination of 4-n-nonylphenol (NP), bisphenol A (BPA), estrone (E1), 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) in drinking waters.
In the literature analytical articles seldom provide details regarding fragmentation pathways. In this paper spectra of the five EDCs in negative ESI were interpreted with the support of accurate mass spectra acquired by a quadrupole time-of-flight instrument; fragmentation pathways were also proposed. The chromatographic separation of EDCswas optimized on a Pinnacle DB Biphenylic column with awater–acetonitrile gradient.Quantitative analysiswas performed inmultiple reaction monitoring (MRM) mode using bisphenol A-d16 (BPA-d16) as internal standard; calibration curves showed good correlation coefficients (0.9989–0.9997). All figures of merit of the method were satisfactory; limits of detection were in the range 0.2–0.4 ng/ml. The method was applied to the determination of the analytes in waters sampled by polar organic chemical integrative samplers in
a drinking water treatment plant. Rather low concentration of BPA, NP and E1 were measured in the inlet, while none of theconsidered EDCs was detected in the outlet
Development of a fast liquid chromatography-tandem mass spectrometry method for the determination of endocrine disrupting compounds in waters
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An improved method for simultaneous analysis of aminothiols in human plasma by high performance liquid chromatography with fluorescence detection
No full textA new method for the simultaneous determination of d- and l-lactic acid in human plasma has been developed using high-performance liquid chromatography (HPLC) with fluorescence detection. This method is based on the reaction of lactic acid with (2S)-2-amino-3-methyl-1-[4-(7-nitro-benzo-2,1,3-oxadiazol-4-yl)-piperazin-1-yl]-butan-1-one (NBD-PZ-Val) in the presence of O-(7-azobenzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate (HATU) and N-ethyldiisopropylamine (DIEA) to produce fluorescent diastereomeric derivatives that were easily monitored fluorimetrically at ex = 490nm and em = 532 nm. The separation was achieved by use of a C18 analytical column (Synergy Hydro 150mm×3mm i.d., 4m). The calibration curve was linear over the on-column concentration range of 10–200 mol/L for d-lactic acid and 0.5–4.0 mmol/L for l-lactic acid. The sensitivity was good with a limit of detection of 5.24 mol/L for d-lactic acid and 0.15 mmol/L for l-lactic acid. The analytical method was successfully applied to human plasma samples from normal healthy subjects
Polar Organic Chemical Integrative Samplers (POCIS) for the determination of endocrine disrupting compounds in water by means of GC-MS and LC-MS
No full textElectrospray ionization ion trap multiple-stage mass spectrometric fragmentation pathways of leucine and isoleucine: an ab initio computational study
No full textWe recently demonstrated the possibility to distinguish between leucine and isoleucine in several tryptic peptides by means of consecutive tandem mass steps (Armirotti et al. J. Am. Soc. Mass Spectrom. 2007; 18: 57), exploiting a gas-phase rearrangement of the immonium ion of Ile. In the
present paper we explore the tandem mass spectrometric behaviour of the two amino acids. We propose a plausible structure for the diagnostic m/z 69 ion of Ile, that was reported for the first time in 1996 (Hulst and Kientz J. Mass. Spectrom. 1996; 31: 1188), and we explain why its formation is favoured with respect to Leu. Our conclusions are supported by ab initio quantum chemistry calcultations and isotope-labelled standards experiments
A straight access to functionalized carbazoles by tandem reaction between indole and nitrobutadienes
No full textAs a continuation of our research on the synthetic exploitation of the nitrobutadienic building-blocks obtained from the ring-opening of nitrothiophenes, we herein report about their reaction with the π-nucleophilic indole. Thanks to their double Michael-acceptor nature, 2,3-dinitro and 2-nitro-3-phenylsulfonyl substituted 1,3-butadienes produce poly-functionalized carbazoles through a double (inter-+intra-molecular) conjugate addition, followed by aromatization of the newly built ring. Significance is attached to the results obtained in fluorinated solvents such as trifluoroethanol, whereby a mild process, with no need for catalysis, overcomes some practical difficulties otherwise limiting the scope of the reaction. Besides the mechanistic aspects, the reaction encompasses motifs for a synthetic interest, mainly in the field of further-tunable arylcarbazoles endowed with predictable applicative properties, e.g., as fluorescent devices
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