14,303 research outputs found
Detection of Optical Activity as a Sign of Life
Gas liquid chromatographic techniques for detection of optical activity as sign of lif
Chromatography of beer
The objectives of the review are the collection, concise description and evaluation of the various chromatographic techniques used for the
separation and quantitative determination of macro- and microcomponents present in beers
Photochemical behavior of the drug atorvastatin in water.
Atorvastatin undergoes a self-sensitized photooxygenation by sunlight in water. The main photoproducts, isolated by chromatographic
techniques, have been identified by spectroscopic means. They present a lactam ring arising from an oxidation of pyrrole ring and an
alkyl/aryl shift. A mechanism involving singlet oxygen addition and an epoxide intermediate is suggested
Amino acid analysis
The process and apparatus for qualitative and quantitative analysis of the amino acid content of a biological sample are presented. The sample is deposited on a cation exchange resin and then is washed with suitable solvents. The amino acids and various cations and organic material with a basic function remain on the resin. The resin is eluted with an acid eluant, and the eluate containing the amino acids is transferred to a reaction vessel where the eluant is removed. Final analysis of the purified acylated amino acid esters is accomplished by gas-liquid chromatographic techniques
Use of high pressure liquid chromatography in the study of liquid lubricant oxidation
The general principles of classical liquid chromatography and high-pressure liquid chromatography (HPLC) are reviewed, and their advantages and disadvantages are compared. Several chromatographic techniques are reviewed, and the analysis of a C-ether liquid lubricant by each technique is illustrated. An analysis by size exclusion chromatography of an ester lubricant, which had been degraded using a micro-oxidation apparatus, is illustrated to show how HPLC can be used in the study of high-temperature lubricant degradation
Unusual products of the aqueous chlorination of atenolol
The reaction
of the drug atenolol
with hypochlorite
under conditions
that simulate
wastewater
disinfection
was investigated.
The pharmaceutical
reacted in 1 h yielding
three products
that were
separated
by chromatographic
techniques
and characterized
by spectroscopic
features.
Two unusual
products
2-(4-(3-(chloro(2-chloropropan-
2-yl)amino)-2-hydroxypropoxy)
phenyl) acetamide
and 2-(4-
(3-formamido-
2-hydroxypropoxy)
phenyl) acetamide
were obtained along with 2-(4-hydroxyphenyl)
acetamide.
When the reaction
was stopped at shorter times only 2-(4-(3-amino-2-hydroxypropoxy)
phenyl) acetamide
and the dichlorinated
product
were detected. Tests performed
on the seeds of
Lactuca
sativa
show that chlorinated
products
have phytotoxic
activity
Current developments in LC-MS for pharmaceutical analysis
The current developments in liquid chromatography-mass spectrometry (LC-MS) and its applications to the analysis of pharmaceuticals are reviewed. Various mass spectrometric techniques, including electrospray and nanospray ionization, atmospheric pressure chemical ionization and photoionization and their interface with liquid chromatographic techniques are described. These include high performance liquid chromatography, capillary electrophoresis and capillary electrochromatography and the advantages and disadvantages of each technique are discussed. The applications of LC-MS to the studies of in vitro and in vivo drug metabolism, identification and characterization of impurities in pharmaceuticals, analysis of chiral impurities in drug substances and high-throughput LC-MS-MS systems for applications in the “accelerated drug discovery” process are described
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