scholarly journals Novel Microcystins from Planktothrix prolifica NIVA-CYA 544 Identified by LC-MS/MS, Functional Group Derivatization and 15N-labeling

Marine Drugs ◽  
2019 ◽  
Vol 17 (11) ◽  
pp. 643 ◽  
Author(s):  
Vittoria Mallia ◽  
Silvio Uhlig ◽  
Cheryl Rafuse ◽  
Juris Meija ◽  
Christopher O. Miles
Keyword(s):  
Functional Group ◽  
Profile Analysis ◽  
Sulfide Oxidation ◽  
Liquid Chromatography Mass Spectrometry ◽  
Cyanobacterium Anabaena ◽  
Product Ions ◽  
15N Labeling ◽  
Low Levels ◽  
Isotopic Profile

Microcystins are cyclic heptapeptides from cyanobacteria that are potent inhibitors of protein phosphatases and are toxic to animals and humans. At present, more than 250 microcystin variants are known, with variants reported for all seven peptide moieties. While d-glutamic acid (d-Glu) is highly-conserved at position-6 of microcystins, there has been only one report of a cyanobacterium (Anabaena) producing microcystins containing l-Glu at the variable 2- and 4-positions. Liquid chromatography–mass spectrometry analyses of extracts from Planktothrix prolifica NIVA-CYA 544 led to the tentative identification of two new Glu-containing microcystins, [d-Asp3]MC-ER (12) and [d-Asp3]MC-EE (13). Structure determination was aided by thiol derivatization of the Mdha7-moiety and esterification of the carboxylic acid groups, while 15N-labeling of the culture and isotopic profile analysis assisted the determination of the number of nitrogen atoms present and the elemental composition of molecular and product-ions. The major microcystin analog in the extracts was [d-Asp3]MC-RR (1). A microcystin with an unprecedented high-molecular-mass (2116 Da) was also detected and tentatively identified as a sulfide-linked conjugate of [d-Asp3]MC-RR (15) by LC–HRMS/MS and sulfide oxidation, together with its sulfoxide (16) produced via autoxidation. Low levels of [d-Asp3]MC-RW (14), [d-Asp3]MC-LR (4), [d-Asp3,Mser7]MC-RR (11), [d-Asp3]MC-RY (17), [d-Asp3]MC-RF (18), [d-Asp3]MC-RR–glutathione conjugate (19), and [d-Asp3]MC-RCit (20), the first reported microcystin containing citrulline, were also identified in the extract, and an oxidized derivative of [d-Asp3]MC-RR and the cysteine conjugate of 1 were partially characterized.

scholarly journals Analysis of allergenic residues in wines by triple quadrupole LCMS

2019 ◽  
Vol 12 ◽  
pp. 04012
Author(s):  
F.R. Spinelli ◽  
G.J. Cargnel ◽  
A.P. Drehmer ◽  
C. Blatt ◽  
M. Baptistão ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Triple Quadrupole ◽  
Liquid Chromatography Mass Spectrometry ◽  
Treatment Practices ◽  
Unambiguous Determination ◽  
Allergenic Proteins ◽  
Beta Casein ◽  
Fining Agents ◽  
Low Levels

During the winemaking are used technology coadjuvants, between them: albumin, caseinates and lysozyme. These compounds have great oenological properties, however, the presence of their residues can represent risks to people who are allergic to them because they are derived from eggs and milk. Mass spectrometry methods enables unambiguous determination of allergenic proteins at low levels in wines. Therefore, the aim of this study was to determine the concentrations of ovalbumin, alpha-casein, beta-casein and lysozyme in experimental wines treated with different concentrations of them by triple quadrupole liquid chromatography mass spectrometry with Jet Stream Electrospray Ionization (ESI). The wines were elaborated and treated with different concentrations of albumin, lysozyme and potassium caseinate. Bentonite and decantation were used for the removal of the fining agents. The quantification limits (LOQ) for ovalbumin, a-casein, b-casein and lysozyme were: 0.002 mg/L, 0.24 mg/L, 0.75 mg/L and 0.04 mg/L, respectively. Non residues of the proteins were identified in the experimental wines treated with the different amounts of potassium caseinate, albumin and lysozyme, analyzed in this study. These results provide an evidence of the absence of residues of caseinate, albumin and lysozyme in the concentrations tested in the wines if good treatment practices are followed.

scholarly journals Determination of the Anthraquinones Aloe-Emodin and Aloin-A by Liquid Chromatography with Mass Spectrometric and Diode Array Detection

2007 ◽  
Vol 90 (1) ◽  
pp. 28-42 ◽  
Author(s):  
Mahmoud A Elsohly ◽  
Waseem Gul ◽  
Bharathi Avula ◽  
Ikhlas A Khan
Keyword(s):  
Liquid Chromatography ◽  
Internal Standard ◽  
Diode Array ◽  
Diode Array Detection ◽  
Liquid Chromatography Mass Spectrometry ◽  
Array Detection ◽  
Aloe Emodin ◽  
Low Levels ◽  
Uv Range

Abstract Methods using liquid chromatography/mass spectrometry (LC/MS) and LC with diode array detection (DAD) in the UV range (LC/UV) were developed for the determination of low levels of the anthraquinones aloe-emodin and aloin-A (barbaloin) in aloe-based products. The methods were used to analyze several commercial products (liquids, semisolids, and solids) for the 2 anthraquinones. The wavelengths used for quantification of aloin-A, aloe-emodin, and emodin (internal standard) by DAD were 357, 257, and 289 nm, respectively. The on-column sensitivities were 0.25 and 0.05 ng by LC/UV and 0.01 and 0.025 ng by LC/MS for aloin-A and aloe-emodin, respectively. The methods are simple and sensitive and provide reproducible results; therefore, they are suitable for the determination of these anthraquinones in various aloe-based products.

Rapid determination of the original boron isotopic composition from altered basaltic glass by in situ secondary ion mass spectrometry

2020 ◽  
Vol 35 (2) ◽  
pp. 238-245 ◽  
Author(s):  
Miaohong He ◽  
Xiaoping Xia ◽  
Xiaolong Huang ◽  
Jinlong Ma ◽  
Jieqiong Zou ◽  
...  
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Profile Analysis ◽  
Rapid Determination ◽  
Basaltic Glass ◽  
The Core ◽  
Secondary Ion ◽  
Isotopic Profile ◽  
Boron Isotopic Composition

Rapid determination of the original boron composition from altered basaltic glass by SIMS boron isotopic profile analysis from the core to rim.

Spectrophotometric Determination of Raceophenidol in Feed at Very Low Levels

1968 ◽  
Vol 51 (4) ◽  
pp. 752-755
Author(s):  
Edward L Pratt ◽  
Morris E Auerbach
Keyword(s):  
Spectrophotometric Determination ◽  
Growth Promotion ◽  
Ultraviolet Spectrum ◽  
Average Value ◽  
Collaborative Studies ◽  
Low Levels ◽  
Concentration Levels

Abstract Raceophenidol in feed at concentration levels intended for growth promotion of poultry can be estimated by a curvature inversion measurement related to the ultraviolet spectrum of derived p-methylsulfonylbenzaldehyde. The drug can be accurately measured at the 0.0005% level. Collaborative studies on the method showed an average value of 94 ± 10% of claim. The method is recommended for adoption as official, first action.

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