Efficient steps towards the synthesis of novel (phenyl)(1'-aryl-1,5,5'-triphenyl[3,3'-bi-1Hpyrazol]-
4-yl)methanones 4a-e were developed. The procedure starts from 1-(4-benzoyl-1,5-diphenyl-
1H-3-pyrazolyl)-3-phenyl-2-propyn-1-one (2) which was synthesized by a palladium catalyzed crosscoupling
reaction. Compound 2 reacted with various hydrazines to give (E)-(phenyl)[1,5-diphenyl-3-
[3-phenyl-1-(2-arylhydrazono)-2-propyn-1-yl]-1H-4-pyrazolyl]methanones E-3a-e. The bis-pyrazole
derivatives 4a-e were synthesized from electrophilic cyclization reaction of α,β-acetylenic hydrazones
E-3a-e and copper(I) iodide. All synthesized compounds were characterized by FT-IR, 1H, 13C NMR
and Mass spectral analyses.
The acid metabolites and the cellular fatty acids of three strains of Neisseria meningitidis grown in a chemically defined liquid medium were determined with computerized frequency-pulsed electron capture gas-liquid chromatography. Five acids not previously reported were subsequently identified: isobutyric, octanoic, decenoic (C10:1), dodecenoic (C12:1), and tetradecenoic (C14:1). These acids were produced during active metabolism and were not detected as cellular constituents. The frequency-pulsed electron capture gas-liquid chromatography methods which we used provide a rapid, reliable, sensitive means of detecting both these and other metabolic and cellular acids in spent culture medium.
Abstract
A procedure is described for the determination of trichlorfon in a soluble powder formulation by gas-liquid chromatography. Silylation prevents on-column degradation of trichlorfon to dichlorvos. The procedure provides quantitative recovery from the formulation as demonstrated by a spiking study. A relative standard deviation of less than 2% was obtained for 6 replicate assays of a single lot of formulation. The mass spectral fragmentations of trichlorfon and trichlorfon-trimethylsilyl ether are described.
An accurate and rapid method, was devised for the identification and quantitation of dimethyl yellow dye in curry, based on liquid chromatography-tandem mass spectrometry interfaced with electrospray. Mass spectral acquisition was done in positive ion mode applying two fragmentation transitions to provide a high degree of selectivity. The extraction system provided a very high recovery (100.0% to 105.8%) and good results were obtained for the limit of detection (5 μg/kg) and limit of quantitation (16 μg/kg). The applicability of the method to identifing and quantifing the unauthorised dimethyl yellow dye in curry was demonstrated.
Lipidomics has great promise in various applications; however, a major bottleneck in lipidomics is the accurate and comprehensive annotation of high-resolution tandem mass spectral data. While the number of available lipidomics software has drastically increased over the past five years, the reduction of false positives and the realization of obtaining structurally accurate annotations remains a significant challenge. We introduce Lipid Annotator, which is a user-friendly software for lipidomic analysis of data collected by liquid chromatography high-resolution tandem mass spectrometry (LC-HRMS/MS). We validate annotation accuracy against lipid standards and other lipidomics software. Lipid Annotator was integrated into a workflow applying an iterative exclusion MS/MS acquisition strategy to National Institute of Standards and Technology (NIST) SRM 1950 Metabolites in Frozen Human Plasma using reverse phase LC-HRMS/MS. Lipid Annotator, LipidMatch, and MS-DIAL produced consensus annotations at the level of lipid class for 98% and 96% of features detected in positive and negative mode, respectively. Lipid Annotator provides percentages of fatty acyl constituent species and employs scoring algorithms based on probability theory, which is less subjective than the tolerance and weighted match scores commonly used by available software. Lipid Annotator enables analysis of large sample cohorts and improves data-processing throughput as compared to previous lipidomics software.
Rapid detection of dimethyl yellow dye in curry by liquid chromatography-electrospray-tandem mass spectrometry