Chromatography-negative Electrospray Ionization Tandem Mass Research Articles

Determination of emerging and priority industrial pollutants in surface water and wastewater by liquid chromatography–negative electrospray ionization tandem mass spectrometry

A method for the simultaneous determination of six perfluoroalkyl compounds (perfluorooctanesulfonic acid (PFOS) and five perfluoroalkyl carboxylic acids), five phenolic compounds (nonylphenol (NP), bisphenol A (BPA), and methyl-, ethyl- and propylparabens), and the brominated flame retardant hexabromocyclododecane (HBCDD) in surface water and effluent wastewater has been developed. The selected pollutants include eight of the industrial pollutants (PFOS and derivatives, NP, and HBCDD) that could be regulated in surface water according to an European Union Directive proposal and four compounds of great concern because their estrogenicity (BPA and parabens). The method is based on solid-phase extraction and determination by high-performance liquid chromatography-triple quadrupole mass spectrometry in negative electrospray ionization mode. Method quantitation limits of NP, PFOS and derivatives, and HBCDD allow its application for routinely control of surface water according to the EU proposal of directive.

Development and validation of a method for the determination of nicotinic acid in human plasma using liquid chromatography-negative electrospray ionization tandem mass spectrometry and its application to a bioequivalence study

For 60 years, nicotinic acid (NA) has been used as a potent vitamin in milligram doses while NA in gram doses has been administrated as a broad-spectrum lipid drug potent.

Characterization of Phenolic Compounds in Fruit Extracts of Three Medicinal Plants Using Liquid Chromatography-Negative Electrospray Ionization Tandem Mass Spectrometry

The characterization of phenolics was done in fruits of three medicinal plants such as Aegle marmelos, Terminalia chebula and Garcinia gummi-gutta using liquid chromatography coupled with Quadra pole mass spectroscopy in ESI negative mode. The accurate mass data for the molecular ions were processed using the software Mass Hunter work station (Agilent Technologies), which provided a list of possible elemental formulas generated using the Molecular featured extraction editor. The subsequent structural characterization was carried out by MS/MS fragmentation. The total phenolics of each sample were also estimated spectrophotometrically using Folin Ciocalteu method.

Quantification of Flavonoids in Black Rice by Liquid Chromatography-Negative Electrospray Ionization Tandem Mass Spectrometry

Systematic identification and structural characterization of flavonoids and their glycosides in bran extracts of seven Thai black rice varieties were performed by sequential uses of reversed-phase HPLC with a photodiode array detector and a combined electrospray ionization tandem mass spectrometer. Eleven flavonoids were detected, and six of these were found for the first time in rice bran. These were taxifolin-7-O-glucoside, myricetin-7-O-glucoside, isorhamnetin-3-O-acetylglucoside, isorhamnetin-7-O-rutinoside, 5,6,3',4',5'-pentahydroxyflavone-7-O-glucoside, and 5,3',4',5'-tetrahydroxyflavanone-7-O-glucoside. The quantitative results revealed that different rice varieties possessed flavonoids in different concentrations. The most abundant glycoside derivative of flavonoids widely distributed among the rice varieties was monoglucoside, such as quercetin-3-O-glucoside, isorhamnetin-3-O-glucoside, and isorhamnetin-3-O-glucoside.

Rapid simultaneous determination of dexamethasone and betamethasone in milk by liquid chromatography tandem mass spectrometry with isotope dilution

A simple, sensitive and reliable analytical method for the rapid simultaneous determination of dexamethasone and betamethasone in milk by high performance liquid chromatography–negative electrospray ionization tandem mass spectrometry (HPLC–NESI-MS/MS) with isotope dilution was developed. Samples were directly purified through C 18 cartridge. Then the eluate was dried under nitrogen and residues were dissolved in mobile phase. Samples were analyzed by HPLC–MS/MS on a Hypercarb graphite column with a mixture of acetonitrile–water–formic acid as mobile phase. The samples were quantified using dexamethasone-D 4 as an internal standard. The procedure was validated according to the European Union regulation 2002/657/EC determining specificity, decision limit (CCα), detection capability (CCβ), trueness, precision, linearity and stability. The method is demonstrated to be suitable for the determination of dexamethasone and betamethasone in milk. The total time required for the analysis of one sample was about 35 min.

Separation and characterization of phenolic compounds in argan fruit pulp using liquid chromatography–negative electrospray ionization tandem mass spectroscopy

Liquid chromatography (LC) coupled to negative electrospray ionization (ESI) tandem mass spectrometry (MS/MS) was used for the sensitive identification of phenolic compounds in argan fruit pulp. Sixteen compounds were identified, mainly flavonoid glycosides and flavonoid aglycons.

Investigation of Lepechinia graveolens for its antioxidant activity and phenolic composition

A bioguided separation of Lepechinia graveolens (Reg.) Epling. (Lamiaceae) for antioxidant activity was carried out. The ethyl acetate fraction (EAF) from the methanolic extract was chromatographed on Sephadex LH-20 affording five active fractions. The radical scavenging activity of each fraction, as well as that of the isolated compounds, was tested using three different methods. The major isolated antioxidant compounds were identified as luteolin-7- O-glucuronide, rosmarinic acid, and rosmarinic acid methyl ester by means of 1 H and 13 C NMR and mass spectrometry. Twenty other minor phenolic compounds were determined by liquid chromatography-negative electrospray ionization tandem mass spectrometry. They included hydroxycinnamic acid derivatives, flavonoids and phenolic diterpenes. The major phenolic compound was found to be rosmarinic acid, which was quantitatively determined by high-performance liquid chromatography (HPLC)-diode array detector (DAD). The content of rosmarinic acid was 2.8% (referred to dry weight), this amount being around 30% of the total phenolic content (TPH) of the crude extract. It can be concluded that the antioxidant activity of Lepechinia graveolens was mainly due to rosmarinic acid, which allows this plant species to be considered as a potential new source of this well known natural antioxidant.