Direct separation of the enantiomers of cetirizine and related compounds by reversed-phase chiral HPLC

Summary Direct separations of the enantiomers of cetirizine and related compounds have been achieved by reversed-phase HPLC on the Chiralcel OD-R, a polysaccharide-derived chiral stationary phase; the mobile phase was usually perchlorate solution supplemented with acetonitrile. Resolution of the enantiomers of cetirizine and related compounds was good. The effect of the acetonitrile content of the mobile phase was investigated, and the effect of the structure of the chiral compounds on their behavior on the Chiralcel OD-R column is discussed.     

Determination of oxaliplatin in human plasma and plasma ultrafiltrate by graphite-furnace atomic-absorption spectrometry

A method for sensitive determination of the anti-cancer agent oxaliplatin in human plasma and human plasma ultrafiltrate (pUF) is presented. The method is based on the quantification of platinum by graphite-furnace atomic-absorption spectrometry, with Zeeman correction and an atomisation temperature of 2,700°C. Sample pretreatment involves dilution of the samples with a solution containing 0.15 mol L^–1 NaCl and 0.20 mol L^–1 HCl in water. Validation was performed in accordance with the most recent FDA guidelines for bioanalytical method validation. All results were within requirements. The validated ranges of quantification were 0.10–400 mol L^–1 for human pUF and 0.50–400 mol L^–1 for plasma. The assay is now successfully used to support pharmacokinetic studies of cancer patients treated with oxaliplatin.     

Exogenous donors of nitric oxide (a chemical aspect)

The review considers problems related to the formation, in the living organism, of nitric oxide, a versatile and vitally important regulator of cell metabolism. The pathways of formation of endogenous nitric oxide from L-arginine are discussed and the main approaches to increasing the NO concentration by introducing various types of exogenous nitric oxide donors into the organism and chemical and biological characteristics of these donors are considered. Primary attention is devoted to the known drugs that were shown to release NO under hydrolytic, oxidative, or reductive conditions. The solution of problems related to the elucidation of the mechanisms of drug action requires that the formation of nitric oxide be taken into account.     

High-performance liquid chromatography of ternary nickel dithiocarbamate complexes derived from some sympathomimetic drugs

Summary Nickel dithiocarbamate complexes derived from some sympathomimetic drugs are examined on silica Radial-Pak columns using binary solvents containing a small percentage of an organic polar modifier. Both the type and concentration of this modifier was found to influence the separation of the ternary from the parent binary complexes. When the two ligands in a ternary complex are racemic to each other, separation of the ternary complex is only possible when certain structural requirements of the molecule are fulfilled. Ternary complexes which contain structurally similar, but nonracemic ligands, are shown to be readily separated from binary complexes. When two such complexes differ only in that one of the ligands in one is enantiomeric to a ligand in the second complex, then it can be shown that the ternary complex with the (+) enantiomer ligand elutes faster from the silica column than the one with the (–) enantiomer ligand. An example of the use of ternary complexes for the identification of optical and structurally related impurities in pharmaceutical products is also given.     

Analysis of drugs by AAS via formation of ion pairs

A new procedure for determining nitrogenated bases by forming ion pairs with Fe(SCN)6^3– is studied. The method consists of extracting the ion pair formed by a nitrogenated base and the inorganic complex Fe(SCN)6^3– into an organic phase, and measuring the iron in the organic phase by AAS at 248.3 nm. The optimal experimental conditions for determining amylocaine, avacan, bromhexine, diphenhydramine and papaverine are studied. The organic phase used is 1,2-dichloroethane. The standard deviation of the method varies between 10^–1 and 10^–2. The interferences produced by various substances are studied.     

含钼化合物及其配合物的抗癌抗肿瘤活性

钼是生命体所必需的微量元素。本文介绍了钼在人体中的作用，钼缺乏和钼过量对人体的影响，并介绍了含钼化合物以及配合物的抗癌抗肿瘤研究情况。     

An ultrasensitive method for the determination of thiouracil and phenylthiouracil using capillary zone electrophoresis and laser-induced fluorescence detection

This paper reports the development of a method based on capillary electrophoresis with laser-induced fluorescence detection for the simultaneous determination of thiouracil (TU) and phenylthiouracil (PhTU) with high sensitivity (nanomolar range, i.e., attomoles detected). After derivatization with 5-iodoacetamidofluorescein, the analytes were separated by capillary zone electrophoresis using 20 mM phosphate buffer (pH 10.0) and quantified by fluorescence detection. The linearity range, precision, recovery, and detection limits were determined, and the method was shown to be applicable for the determination of TU and PhTU in spiked feed samples and urine.     

薄层色谱用纤维素苯甲酸酯类手性固定相的制备及色谱性能

用超声方法合成了3种纤维素苯甲酸酯类手性固定相，三（苯甲酰基）纤维素（CTB）、三（4－甲基苯甲酰基）纤维素（CTMB）、三（4－硝基苯甲酰基）纤维素（CTPNB）；该类手性固定相（CSP）用于薄层色谱分离手性药物对映体，采用合适的展开剂系统，共有6对含氮手性药物获得了安全分离；比较了3种手性固定相的拆分性能，表明CTB和CTMB对手性药物显示出良好的拆分性能，而CTPNB的拆分性能较差。     

Supported Liquid Membrane Work-Up of Blood Plasma Samples Coupled On-Line to Liquid Chromatographic Determination of Basic Antidepressant Drugs

An automated sample pretreatment of human blood plasma for liquid chromatographic determination of three antidepressant drugs, dibenzepine; a tricyclic antidepressant (TCA), reboxetine; a selective noradrenaline reuptake inhibitor (SNRI) and fluvoxamine; a selective serotonin reuptake inhibitor (SSRI), based on supported liquid membrane (SLM) for unsurpassed sample clean-up and analyte enrichment, has been developed. The chromatograms after enrichment of plasma blank and aqueous blank are virtually indistinguishable. The entire analytical procedure revealed good linearity and low detection limits of 5, 15 and 20 ng mL^–1 for dibenzepine, reboxetine and fluvoxamine, respectively. No carry-over effects were noted. The repeatability of extraction at three concentrations in the range 40–150 ng mL^–1 for the three drugs was between ca. 3% and 7% as relative standard deviation. The reproducibility relative standard deviation during three different days (replacing the membrane each day) was not significantly higher.     

Preformulation compatibility studies of etamsylate and fluconazole drugs with lactose by DSC

Chemical compatibility of two drugs, namely, etamsylate and fluconazole was studied with lactose as excipient, employing differential scanning calorimetry (DSC) and X-ray diffraction (XRD) techniques. The DSC patterns recorded for the mixtures of both the drugs with the common excipient (lactose) indicated that fluconazole as well as etamsylate were incompatible with lactose at high temperatures. X-ray diffraction patterns recorded for pure drugs and lactose and the mixtures of individual drugs with lactose prepared at room temperature by intimate grinding of the components revealed incompatibility of both the drugs with lactose also at room temperature. This revised version was published online in July 2006 with corrections to the Cover Date.