Unexpected benzimidazole ring formation from a quinoneimide species in the presence of ammonium acetate as supporting electrolyte used in the coupling of electrochemistry with mass spectrometry

2015 ◽  
Vol 29 (5) ◽  
pp. 456-460 ◽  
Author(s):  
Ugo Bussy ◽  
Ulrik Jurva ◽  
Renaud Boisseau ◽  
Moa Andresen-Bergström ◽  
Virginie Silvestre ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Ammonium Acetate ◽  
Supporting Electrolyte ◽  
Ring Formation ◽  
Benzimidazole Ring

scholarly journals Simultaneous Determination of Cortisol and Cortisone from Human Serum by Liquid Chromatography-Tandem Mass Spectrometry

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Sanghoo Lee ◽  
Hwan-Sub Lim ◽  
Hye-Jin Shin ◽  
Seol-A Kim ◽  
Jimyeong Park ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Tandem Mass Spectrometry ◽  
Ammonium Acetate ◽  
Cortisol Concentration ◽  
Tandem Mass ◽  
Chromatography Tandem Mass Spectrometry ◽  
Liquid Chromatography Tandem Mass ◽  
Cortisol Ratio

A fast, sensitive, and selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was validated and then the levels of cortisol and cortisone from sera of healthy adults were determined by the LC-MS/MS method. One hundredμL of serum sample was directly extracted by adding 2 mL ethyl acetate, followed by chromatographic separation on a C18 column with a mobile phase consisting of 5 mM ammonium acetate and methanol (25 : 75, v/v). The precision, accuracy, and average recovery of the method were 1.5–5.3%, 95.4–102.5%, and 96.4% for cortisol, and 1.9–6.0%, 89.2–98.8%, and 79.9% for cortisone, respectively. The method was linear from 1.0 to 500.0 ng/mLr2=0.999for cortisol and 2.5 to 100.0 ng/mLr2=0.998for cortisone. The limits of detection (LOD) and quantification (LOQ) were 0.2 and 1.0 ng/mL for cortisol, and 1.0 and 2.5 ng/mL for cortisone, respectively. The average cortisol concentration (133.9±63.7 ng/mL) of samples collected between 9:00 and 11:00 a.m. was higher approximately 4.4 times than that of cortisone (30.5±10.7 ng/mL)P<0.0001. The average cortisone/cortisol ratio was 0.225. Therefore, the LC-MS/MS method may be useful for the diagnosis of some adrenal diseases and the assessment of 11β-hydroxysteroid dehydrogenase (11β-HSD) activity in clinical laboratories.

scholarly journals Application of multiple reaction monitoring for quantitation of sweeteners in food products

2019 ◽  
Vol 10 (3) ◽  
pp. 263-266
Author(s):  
Wafaa Abdou Zaghary ◽  
Ahmed Mostafa Abdalla ◽  
Emily Tawfik Hanna ◽  
Nermeen Abdallah Shoukry
Keyword(s):  
Mass Spectrometry ◽  
Quality Control ◽  
Mobile Phase ◽  
Ammonium Acetate ◽  
Detection Method ◽  
Multiple Reaction Monitoring ◽  
Gradient Flow ◽  
Reaction Monitoring ◽  
Accuracy And Precision ◽  
Ich Guidelines

A coupled UPLC-MS/MS method has been developed and validated for the simultaneous quantitation of food sweeteners stevioside (STV) and aspartame (ASP). Good chromato-graphic separation was achieved on a Hypersil gold 50×2.1 mm (1.9 μm) column, using a gradient flow of 10 mM ammonium acetate, pH = 2.9 adjusted with formic acid, and 10 mM ammonium acetate in acetonitrile:water (95:5, v:v) as the mobile phase. The eluate was introduced to ESI-Mass spectrometer and scanned using multiple reaction monitoring (MRM). The method was robust, reproducible and easy to use and was validated according to ICH guidelines for the accuracy and precision giving acceptable ranges. The utilization of multiple reaction monitoring improved the selectivity of detection. Method was linear in the ranges of 2-250 ng/mL for STV and ASP. Application of this method on laboratory mixtures of the selected sweeteners was successful. The using of mass spectrometry make the method selective and measurement did not affect the presence of impurities, additive and other ingredients of detection due to the simplicity and sensitivity of this method allows the utilization of method in quality control of STV and ASP.

scholarly journals Analytical Method for Measurement of Tobacco-Specific Nitrosamines in E-Cigarette Liquid and Aerosol

2018 ◽  
Vol 8 (12) ◽  
pp. 2699 ◽  
Author(s):  
Yoon-Seo Lee ◽  
Ki-Hyun Kim ◽  
Sang Lee ◽  
Richard Brown ◽  
Sang-Hee Jo
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Detection Limit ◽  
Ammonium Acetate ◽  
Tandem Mass ◽  
Average Recovery ◽  
Chromatography Tandem Mass Spectrometry ◽  
Liquid Chromatography Tandem Mass ◽  
Tobacco Specific Nitrosamines ◽  
Sample Dilution

An experimental method was developed and validated for the collection and analysis of tobacco-specific nitrosamines (TSNAs) that are present in electronic cigarette (EC) liquid or are released from aerosol samples using a liquid chromatography-tandem mass spectrometry (LC-MS/MS) system. As part of this study, the relative recovery of four target TSNAs was assessed by spiking standards in a mixture of propylene glycol and vegetable glycerin. Recovery was assessed against two major variables: (1) the chemical media (solution) selected for sample dilution (acetonitrile [ACN] vs. ammonium acetate [AA]) and (2) the type of sampling filter used (Cambridge filter pad [CFP] vs. quartz wool [QW] tube). The average recovery of TSNAs in terms of variable 1 was 134 ± 22.1% for ACN and 92.6 ± 8.27% for AA. The average recovery in terms of variable 2 was 83.4 ± 7.33% for QW and 58.5 ± 12.9% for CFP. Based on these conditions, the detection limits of N′-nitrosonornicotine (NNN), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), N′-nitrosoanatabine (NAT), and N′-nitrosoanabasine (NAB) were calculated as 4.40, 4.47, 3.71, and 3.28 ng mL−1, respectively. The concentration of TSNAs in liquid and aerosol samples of six commercial EC solutions was measured as below the detection limit.

A Novel One-pot Benzimidazole Ring Formation via a Continuous Flow Selective Reductive Cyclization Method

2018 ◽  
Vol 22 (19) ◽  
pp. 1940-1944
Author(s):  
Balazs Szabo ◽  
Ferenc Faigl ◽  
Janos Eles ◽  
Istvan Greiner
Keyword(s):  
Continuous Flow ◽  
Ring Formation ◽  
Reductive Cyclization ◽  
Benzimidazole Ring ◽  
One Pot

Measurement of citrate in urine using liquid chromatography tandem mass spectrometry: comparison with an enzymatic method

2005 ◽  
Vol 42 (5) ◽  
pp. 357-363 ◽  
Author(s):  
BG Keevil ◽  
L Owen ◽  
S Thornton ◽  
J Kavanagh
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Tandem Mass Spectrometry ◽  
Formic Acid ◽  
Ammonium Acetate ◽  
Enzymatic Assay ◽  
Tandem Mass ◽  
Chromatography Tandem Mass Spectrometry ◽  
Liquid Chromatography Tandem Mass ◽  
Urinary Citrate

Background: Measurement of urine citrate is used to assess the risk of further urinary stone formation and to assess the benefit of treatment in affected individuals. We wanted to develop a simple and rapid liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the analysis of urinary citrate and to compare it with our current enzymatic assay. Methods: For the LC-MS/MS assay, samples were prepared in a deep-well block by adding 10 µL of urine and 20 µL of internal standard to 400 µL of water. After mixing, 3 µL of the diluted sample was injected into the LC-MS/MS system. An LC system was used to isocratically elute a C18 column (50 x 2.1 mm) with 0.4 mL/min water containing 2 mmol/L ammonium acetate and 0.1% (v/v) formic acid. A step gradient of 100% methanol containing 2 mmol/L ammonium acetate and 0.1% (v/v) formic acid was used to wash the column. The retention times were 1.4 min for citrate and 1.4 min for d4-citrate. Cycle time was 4.0 min, injection to injection. The analytes were monitored using a tandem mass spectrometer operated in multiple reaction monitoring mode using the following transitions, citrate m/ z 191.0> 111.0 and d4-citrate m/ z 195.0> 113.0. Results: Within and between-batch coefficients of variation were <3% over the range 480-3800 µmol/L. The lower limit of quantification was 24.0 µmol/L. Regression analysis showed LC-MS/MS = 0.8781 (enzymatic assay) + 102.5, r = 0.964, n = 73. Conclusions: We have developed a simple LC-MS/MS method for urinary citrate measurement that shows acceptable performance.

scholarly journals Simultaneous quantitation of nicotinamide riboside and nicotinamide in dietary supplements via HPTLC–UV with confirmation by online HPTLC–ESI–MS

2020 ◽  
Vol 32 (2) ◽  
pp. 128-133
Author(s):  
Andreea Silvia Neamţu ◽  
Andrei Biţă ◽  
Ion Romulus Scorei ◽  
Gabriela Rău ◽  
Ludovic Everard Bejenaru ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Thin Layer ◽  
Electrospray Ionization ◽  
Related Compound ◽  
Mobile Phase ◽  
High Performance ◽  
Ammonium Acetate ◽  
Nicotinamide Riboside ◽  
Esi Mass Spectrometry ◽  
Layer Chromatography

The identification and quantitation of nicotinamide riboside (NAR) and its main related compound (nicotinamide) were achieved using high-performance thin-layer chromatography (HPTLC)–ultraviolet (UV) densitometry with confirmation by online electrospray ionization (ESI)–mass spectrometry (MS). As the stationary phase, HPTLC Si 60 F254 glass plates were employed; the mobile phase was ethanol–1 M ammonium acetate–formic acid (7:1:0.1, v/v/v). No derivatization was applied, and UV densitometry was performed in the absorbance mode (270 nm). The method was validated by specificity, linearity, accuracy, precision, and robustness.

X-Ray Diffraction, Spectroscopic and Morphological Studies of Electrochemically Synthesized Copper(II) Palmitate Complex

2015 ◽  
Vol 1087 ◽  
pp. 96-100
Author(s):  
Norazzizi Nordin ◽  
Wan Zurina Samad ◽  
Kin Hong Liew ◽  
Mohd Ambar Yarmo ◽  
Muhammad Rahimi Yusop ◽  
...  
Keyword(s):  
Surface Morphology ◽  
Ammonium Acetate ◽  
Supporting Electrolyte ◽  
Spectroscopic Studies ◽  
Electrochemical Technique ◽  
X Ray Diffraction ◽  
X Ray ◽  
Morphological Studies ◽  
Cu Foil ◽  
Graphite Rod

Copper (II) palmitate complex was synthesized using an electrochemical technique in the presence of palm-based palmitic acid as the ligand and Cu (II) ions from the slow released of anode material through the electrochemical oxidation of Cu foil. The system consisted of Cu foil and a graphite rod as the anode and cathode, respectively, while ammonium acetate was used as a supporting electrolyte. X-ray diffraction and spectroscopic studies were carried out to characterize the synthesized complexes using powder XRD, XPS, FTIR and UV-Vis. The results obtained showed that the desired Cu (II)Pa complex was successfully synthesized using the electrochemical technique. The surface morphology of the complexes was analyzed using FESEM, and the micrograph obtained showed that the synthesized complexes formed nanosized matchstick-like structures. This conclusion is supported by the TEM micrograph which shows the presence of nanoparticles with different diameter ranges from 2 to 3 nm.

scholarly journals Observation of Intact and Proteolytically Cleaved Amyloid-Beta (1–40)-Oleuropein Noncovalent Complex at Neutral pH by Mass Spectrometry

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3261
Author(s):  
Ioana Cezara Caba ◽  
Raluca Ştefănescu ◽  
Bogdan Ionel Tamba
Keyword(s):  
Mass Spectrometry ◽  
Amyloid Beta ◽  
Binding Sites ◽  
Ammonium Acetate ◽  
Noncovalent Complex ◽  
Ammonium Bicarbonate ◽  
Noncovalent Complexes ◽  
Mass Spectrometers ◽  
Ionization Sources ◽  
Chemical Solutions

Mass spectrometry analyses carried out on mass spectrometers equipped with soft ionization sources demonstrated their utility in the assessment of the formation of noncovalent complexes and the localization of the binding sites. Direct analyses by mass spectrometry of the noncovalent complex formed in acidic and mildly acidic environments by amyloid beta (1–40) peptide and oleuropein have been previously described, and, in several studies, the absorption, metabolism, excretion, and the implications in the prevention and therapy of Alzheimer’s disease of oleuropein have been investigated. Our paper presents modifications of the method previously employed for noncovalent complex observation, namely, the amyloid beta (1–40) pretreatment, followed by an increase in the pH and replacement of the chemical environment from ammonium acetate to ammonium bicarbonate. The formation of noncovalent complexes with one or two molecules of oleuropein was detected in all chemical solutions used, and the amyloid beta (17–28) binding site was identified via proteolytic experiments using trypsin prior to and after noncovalent complex formation. Our results highlight the importance of further studies on the effect of oleuropein against amyloid beta aggregation.

scholarly journals The Usefulness of MS3 to Confirm Poisoning on the Example of Dog Poisoning with Strychnine

Molecules ◽  
2019 ◽  
Vol 24 (20) ◽  
pp. 3765
Author(s):  
Tomasz Śniegocki ◽  
Bartosz Sell ◽  
Andrzej Posyniak
Keyword(s):  
Mass Spectrometry ◽  
High Pressure ◽  
Liquid Chromatography ◽  
Ammonium Acetate ◽  
Stomach Contents ◽  
Postmortem Examination ◽  
Small Animals ◽  
Chromatography Method ◽  
Liquid Chromatography Method

Strychnine is an alkaloid with strong toxic properties. Poisoning results in muscular contractions and death through asphyxiation. Intentional or accidental poisonings with strychnine occur mainly in small animals, especially dogs and occasionally cats. Strychnine can be detected in the liver or stomach contents. Unfortunately, the determination of strychnine in these matrices, especially in postmortem examination, is subject to a significant matrix effect that makes it difficult to confirm the presence of the substance being determined. Therefore, we developed a new liquid chromatography method combined with mass spectrometry. One-gram homogenized samples were extracted and partitioned after adding acetonitrile and 5-mol solution of ammonium acetate. After extraction, the samples were analyzed using high-pressure liquid chromatography-MS/MS/MS. The results of validation fulfil the requirement of the confirmatory criteria according to SANTE/11945/2015 regarding apparent recoveries (98.97% to 104.0%), repeatability (2.9%–4.1%), and within-laboratory reproducibility (3.3%–4.6%). The method can be successfully applied to confirm strychnine poisoning cases.

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