Electrospray Ionization Orbitrap Mass Spectrometry Research Articles

Identification of Glycoside Compounds from Tobacco by High Performance Liquid Chromatography/Electrospray Ionization Linear Ion-Trap Tandem Mass Spectrometry Coupled with Electrospray Ionization Orbitrap Mass Spectrometry

In order to comprehensively screen and identify the glycoside compounds in tobacco, a simple, rapid and sensitive method of high performance liquid chromatography/electrospray ionization linear ion-trap tandem mass spectrometry (HPLC-ESI-LIT/MSn) coupled with electrospray ionization orbitrap mass spectrometry (ESI-Orbitrap-MS) was developed for the first time. As a result, twenty-two glycoside compounds, including eleven alcoholic glycosides, eight phenolic glycosides, two ester glycosides and an indole glycoside, were reliably identified from tobacco with high mass accuracy (within 5 mDa). Among them, four compounds were confirmed as novel molecules and other four compounds, as far as we know, were not reported previously in tobacco. This study provided a useful tool to identify the new structures of glycoside compounds in natural products, especially when there were no reference compounds available.

Determination of anxiolytic veterinary drugs from biological fertilizer blood meal using liquid chromatography high-resolution mass spectrometry.

A liquid environment-friendly agricultural material originating from animal blood, blood meal, was employed to detect anxiolytic veterinary drugs using a combination of liquid-liquid extraction (LLE) and positive electrospray ionization Orbitrap mass spectrometry. Every positive ion of the analytes was consistent with [M+H](+) , and the accurate mass analysis and mass spectral filtration with a 2-ppm mass tolerance window were applied to identify and quantitate the analytes and metabolites. The developed LLE method was validated with the lowest calibrated level, linearity (r(2) ), recovery, repeatability and the within-laboratory reproducibility, which were in the ranges of 0.3-1 µg/L, 0.9963-0.9995, 48.3-117.5%, 1.1-12.6% and 2.3-15.7%, respectively. The LLE method was compared with a solid-phase extraction (SPE) method; however, its recoveries were <70% for most of the analytes despite good repeatability of 1.2-7.4%. The analytes and the ascertained acepromazine, azaperone and xylazine metabolites were monitored in four actual liquid blood meal samples, and none of the targeted compounds were observed.

Quantitative HPLC-MS analysis of nucleotide sugars in plant cells following off-line SPE sample preparation

An analytical workflow was developed for the absolute quantification of uridine diphosphate (UDP)-sugars in plant material in order to compare their metabolism both in wild-type Arabidopsis thaliana and mutated plants (ugd2,3) possessing genetic alterations within the UDP-glucose dehydrogenase genes involved in UDP-sugar metabolism. UDP-sugars were extracted from fresh plant material by chloroform-methanol-water extraction and further purified by solid-phase extraction with a porous graphitic carbon adsorbent with extraction efficiencies between 80 ± 5 % and 90 ± 5 %. Quantitative determination of the UDP-sugars was accomplished through HPLC separation with a porous graphitic carbon column (HypercarbTM) which was interfaced to electrospray ionization Orbitrap mass spectrometry. The problem of instable retention times due to redox processes on the stationary phase were circumvented by grounding of the column effluent and incorporation of a column regeneration procedure using acetonitrile-water containing 0.10 % trifluoroacetic acid. The method was calibrated using external calibration and UDP as internal standard. Calibration functions were approximated by first- or second-order regression analysis for concentrations spanning three orders of magnitude. Upon injecting sample volumes of 2.65 μL, the limits of detection for the UDP-sugars were in the 70 nmol L−1 range. Six different UDP-sugars, including UDP-glucose, UDP-galactose, UDP-arabinose, UDP-xylose, UDP-glucuronic acid, and UDP-galacturonic acid were found in concentrations of 0.4 to 38 μg/g plant material. Data evaluation by analysis of variance (ANOVA) revealed statistically significant differences in UDP-sugar concentrations between wild-type and mutant plants, which were found to conclusively mirror the impaired metabolic pathways in the mutant plants. Figureᅟ Electronic supplementary materialThe online version of this article (doi:10.1007/s00216-014-7746-3) contains supplementary material, which is available to authorized users.

Elemental and spectroscopic characterization of fractions of an acidic extract of oil sands process water

‘Naphthenic acids’ (NAs) in petroleum produced water and oil sands process water (OSPW), have been implicated in toxicological effects. However, many are not well characterized. A method for fractionation of NAs of an OSPW was used herein and a multi-method characterization of the fractions conducted.The unfractionated OSPW acidic extract was characterized by elemental analysis, electrospray ionization-Orbitrap-mass spectrometry (ESI-MS), and an esterified extract by Fourier Transform infrared (FTIR) and ultraviolet–visible (UV) absorption spectroscopy and by comprehensive multidimensional gas chromatography–MS (GCxGC–MS). Methyl esters were fractionated by argentation solid phase extraction (Ag+ SPE) and fractions eluting with: hexane; diethyl ether: hexane and diethyl ether, examined. Each was weighed, examined by elemental analysis, FTIR, UV, GC–MS and GCxGC–MS (both nominal and high resolution MS). The ether fraction, containing sulfur, was also examined by GCxGC–sulfur chemiluminescence detection (GCxGC–SCD).The major ions detected by ESI-MS in the OSPW extract were assigned to alicyclic and aromatic ‘O2’ acids; sulfur was also present. Components recovered by Ag+ SPE were also methyl esters of alicyclic and aromatic acids; these contained little sulfur or nitrogen. FTIR spectra showed that hydroxy acids and sulfoxides were absent or minor. UV spectra, along with the C/H ratio, further confirmed the aromaticity of the hexane:ether eluate.The more minor ether eluate contained further aromatics and 1.5% sulfur. FTIR spectra indicated free carboxylic acids, in addition to esters. Four major sulfur compounds were detected by GCxGC–SCD. GCxGC–high resolution MS indicated these were methyl esters of C18 S-containing, diaromatics with ⩾C3 carboxylic acid side chains.

Lucifensin II, a Defensin of Medicinal Maggots of the BlowflyLucilia cuprina(Diptera: Calliphoridae)

A novel homolog of insect defensin, designated lucifensin II (Lucilia cuprina Wiedemann [Diptera: Calliphoridae] defensin), was purified from hemolymph extract from larvae of the blowfly L. cuprina. The full-length primary sequence of this peptide of 40 amino acid residues and three intramolecular disulfide bridges was determined by electrospray ionization-orbitrap mass spectrometry and Edman degradation and is almost identical to the previously identified sequence of lucifensin (Lucilia sericata Meigen defensin). Lucifensin II sequence differs from that of lucifensin by only one amino acid residue, that is, by isoleucine instead of valine at position 11. The presence of lucifensin II also was detected in the extracts of other larval tissues, such as gut, salivary glands, fat body, and whole body extract.

Structural elucidation of degradation products of a benzopyridooxathiazepine under stress conditions using electrospray orbitrap mass spectrometry – Study of degradation kinetic

1-(4-Methoxyphenylethyl)-11H-benzo[f]-1,2-dihydro-pyrido[3,2,c][1,2,5]oxathiazepine 5,5 dioxide (BZN) is a cytotoxic derivative with very promising in vitro activity. Regulatory authority for registration of pharmaceuticals for human use requires to evaluate the stability of active compound under various stress conditions. Forced degradation of BZN was investigated under hydrolytic (0.1M NaOH, 0.1M HCl, neutral), oxidative (3.3% H2O2), photolytic (visible light) and thermal (25°C, 70°C) settings. Relevant degradation took place under thermal acidic (0.1M HCl, 70°C) and oxidative (3.3% H2O2) conditions. Liquid chromatography-mass spectrometry (LC–MS) analyses revealed the presence of ten degradation products whose structures were characterized by electrospray ionization-orbitrap mass spectrometry. The full scan accurate mass analysis of degradation products was confirmed or refuted using three tools furnished by the MS software: (1) predictive chemical formula and corresponding mass error; (2) double bond equivalent (DBE) calculation; and (3) accurate mass product ion spectra of degradation products. The structural elucidation showed that the tricycle moiety was unstable under thermal acidic and oxidative conditions since four degradation products possess an opened oxathiazepine ring. Then, a simple and fast HPLC–UV method was developed and validated for the determination of the degradation kinetic of BZN under acidic and oxidative conditions. The method was linear in the 5–100μgmL−1 concentration range with a good precision (RSD=2.2% and 2.7% for the repeatability and the intermediate precision, respectively) and a bias which never exceeded 1.6%, whatever the quality control level. With regards to the BZN concentration, a first-order degradation process was determined, with t1/2=703h and 1140h, under oxidative and acidic conditions, respectively.