A new liquid chromatography-tandem mass spectrometry method for determination of bisoprolol in human plasma samples.

Liquid chromatography (LC) coupled with mass spectrometry (MS) detection is one of the most powerful analytical tools for organic compound analysis. The advantages of using LC/MS methods over HPLC methods include: selectivity, chromatographic integrity, peak assignment, structural information, and rapid method development. In this paper, a new liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the determination of bisoprolol in human plasma samples, using metoprolol as internal standard and liquid-liquid extraction procedure.

Analysis of cyanogens with resorcinol and picrate.

The total cyanogenic potential of various substrates (flax seed, stones of peach, plum, nectarine and apricot as well as apple seeds, and various model compounds) was investigated by using the acid hydrolysis method, picrate method, and a novel method based on the reaction of cyanide liberated from plants with resorcinol and picrate. The hydrocyanic acid liberated from cyanogens was trapped by using a 1% sodium bicarbonate. Then, 1 ml of extract was mixed with 1 ml of working reagent containing 160 microg of resorcinol, 320 microg of picric acid, and 30 mg of sodium carbonate, and heated on a boiling water bath for 10 min.

Enhancement of oxygen mass transfer in stirred bioreactors using oxygen-vectors. 1. Simulated fermentation broths.

Oxygen mass transfer represents the most important parameter involved in the design and operation of mixing-sparging equipment for bioreactors. It can be described and analyzed by means of the mass transfer coefficient, k(L) a. The k(L) a values are affected by many factors such as geometrical and operational characteristics of the vessels, media composition, type, concentration and microorganism morphology, and biocatalysts properties.

[Methods of advanced purification-the challenge for biosynthetic antibiotics industry].

Reactive extraction, permeation through liquid membranes and direct extraction are some of the new techniques applied for separation and advanced purification of biosynthetic antibiotics. Compared with the conventional separation techniques, the main advantages of these extraction methods are: high separation efficiency, the avoidance of antibiotics chemical and thermal inactivation, high purity of obtained antibiotics. Furthermore, using reactive extraction or permeation through liquid membrane, the antibiotics can be selective separated from their biosynthesis precursors or from the secondary biosynthetic compounds.

On hypotensive action of some imidazoline derivatives of sulphonamidated aryloxyalkylcarboxylic acids.

New imidazolines derived from sulphonamidated aryloxyalkylcarboxylic acids have been tested for their antihypertensive action and toxicity. The obtained results attest a remarkable biological action, low toxicity and a good absorption in oral administration.

[The specific effects of new phenoxyacetic acid derivatives at the cellular membrane level].

Substances ASFA-2 and ASFA-4, new derivatives of phenoxyacetic acid, induce, in normal conditions, the hyperpolarization of the striated muscle fibre membrane, inhibition the depolarization due to the absence of external Ca2+, the restoration of membrane potential of the liver cells poisoned with ally alcohol and the change of redox potential of the environment. It results that these substances have important pharmacological properties--influence upon the membrane potential and cellular excitability, membrane stabilization, redox modulation and hepatic protection--that can be useful in therapy.