Studies on antimony oxides: Part I

Thermogravimetry (TG), differential thermal analysis (DTA) and X-ray diffraction studies of antimony(III) oxide, (Sb₂O₃), in air, nitrogen and argon atmospheres have been made. In air Sb₂O₃ becomes oxidized to Sb₂O₄ above 510°. The oxidation reaction proceeds in two stages as revealed by the TG and DTA curves. The behaviour of Sb₂O₃ is similar in both N₂ and Ar. Sb₂O₃ remains unaffected up to 430°, above which there is a slow, and continuous mass loss up to 550°. Above 550° Sb₂O₃ volatilizes resulting in an enormous weight loss. X-ray studies of the sublimate and the residue indicate the former to be the cubic form of Sb₂O₃ (Senarmontite) while the residue is the orthorhombic (Valentinite) structure. From the DTA curves in air, N₂ and Ar, the transition temperature for the cubic to the orthorhombic modification has been estimated to be around 610°.     

Luminarin 9: A new fluorescent reagent for the precolumn derivatizatioin of main volatile and non-volatile N-nitrosamines in RP-HPLC

Summary A sensitive precolumn fluorescence derivatization method for low level detection of the, volatile (N-nitrosodimethylamine and N-nitrosopyrrolidine) and non-volatile N-nitrosamines (N-nitrosoproline and N-nitrosodiethanolamine) an high-performance liquid chromatography was developed. This method is based on the denitrosation of the compounds of interest by a mixture of hydrobromic acid and acetic acid to produce the corresponding secondary amines. These are, then, able to react with, a quinolizinocoumarin derivative (luminarin 9^®) to form highly fluorescent labelled N-nitrosamine derivatives. The structural elucidation of the luminarin 9^® derivatives of N-nitrosoproline and N-nitrosodimethylamine by way of example, were established by liquid chromatography-mass spectrometry (LC-MS) and by direct chemical ionization-mass spectrometry (CI-MS). The separation, derivatization and detection conditioins were optimized for all the studied compounds. The detection limits (signal to noise ratio=3) were between 0.4 and 1.0 pmol injected depending on the compound. The calibration graphs were linear for derivatized amounts in the range of 0.5–40 nmol for N-nitrosodimethylamine and N-nitrosopyrrolidine, 0.4–2- nmol for N-nitrosoproline and 1.0–40 nmol for N-nitrosodiethanolamine. The repeatability (RSD less than 3.5%, n=6) and reproducibility (RSD less than 4.8%, n-6) were satisfactory.     

Chloryl nitrate: a novel product of the OClO + NO3 + M recombination

The products of the reaction of OClO with NO3 were investigated between 220 and 298 K using a flow reactor and infrared, visible, and ultraviolet analysis. At temperatures below 250 K new infrared and ultraviolet absorption features were observed and assigned to the novel compound chloryl nitrate (O2ClONO2). Additionally, ClO and NO2 were observed as reaction products, indicating the existence of a second reaction channel. O2ClONO2 formation predominates at temperatures below 230 K. The reaction rate constant at 220 K is estimated to be on the order of 10(-14) cm3 molecule-1 s-1 in 1-5 Torr of helium. These observations suggest that O2ClONO2 may exist in the terrestrial stratosphere.     

Mechanism of antioxidative activity of fluvastatin-determination of the active position

In order to clarify the mechanism of action for the antioxidative activity of fluvastatin sodium (FLV, (+/-)-sodium (3RS, 5RS, 6E)-7-[3-(4-fluorophenyl)-1-(1-methylethyl)-1H-indol-2-yl]-3, 5-dihydroxy-6-heptanoate) and its derivatives, reaction of the corresponding methyl ester of FLV with di-tert-butyl diperoxyoxalate was examined, and the corresponding keto derivative was isolated from the reaction mixture. On the basis of this result, it was concluded that the active site is the allylic carbon conjugated with the indole ring.     

Optimization of simulated moving bed plants with low efficient stationary phases: separation of fructose and glucose

An optimization procedure for simulated moving bed (SMB) plants with low efficient stationary phases is presented. The new aspect is that the desorbent consumption can be cut by 70% by running the plant with lower internal liquid flows and a corresponding larger switch time while the productivity is kept constant. This concept was validated by the separation of fructose and glucose in water on a calcium resin with an eight-column SMB plant. The separation can be predicted well by a true moving bed (TMB) and a simulated moving bed simulation. Adsorption isotherms were determined up to 300 kg/m3 for glucose and 500 kg/m3 for fructose from 25 to 80 degrees C. Experimental SMB runs were performed over a wide range of feed concentrations (10-350 kg/m3) and temperatures (25-80 degrees C). The strong influence of the delay volume is pointed out. For an experimental run with high feed concentration a complete set of data is presented. To reduce biological growth separation at 80 degrees C is recommended.     

An application of activation analysis of aluminum in biological materials

The behavior of aluminum compounds in animals was made clear by using non-destructive neutron activation analysis instead of radiotracer method. Basic aluminum sucrose sulfate (BASS) and dried aluminum hydroxide gel (DAHG) were orally administered to rats. The residual BASS and DAHG on gastric walls of rats were determined by neutron activation analysis. It was obtained the following results that BASS was found at the longer time in the stomach. For reason, it is seemed that BASS is hydrolyzed in gastric juice. And it could not find the aluminum in liver, kidney and spleen.     

Chemical studies on nitrogen heterocyclic skeleton of the Daphniphyllum alkaloids

From a biogenetic point of view, a great variety of related alkaloids isolated from the plant Daphniphyllaceae are related to one another by bond formation or fission. Thus, daphnialcohol acetate (6), a derivative of the degradation products of daphniphylline (1), was subjected to von Braun degradation followed by acid-catalyzed recyclization to give an isomer (8) of daphnialcohol, which has a new type of nitrogen heterocyclic skeleton. Furthermore, daphnilactone-B (3) was converted into a daphniphylline-type compound (19) via a plausible intermediate (21).     

Evaluation of thallium-201 myocardial emission computed tomography based on a comparison with postmortem findings

The correlative study of myocardial perfusion assessed by 201Tl myocardial ECT with the pathological finding of the heart was performed in 10 autopsied cases with mean age of 77 years old (range: 60-90 y). In 6 cases with myocardial infarction (MI) 7 perfusion defects were observed, that was, 3 in anteroseptal wall, 1 in anterolateral wall and 3 in posterior wall on the images of SPECT. Seven MIs were also found in postmortem examination. Six MIs were observed at autopsy corresponding to perfusion defect on SPECT images. In one myocardial perfusion defect at inferoposterior portion on SPECT, a non-transmural MI was found at anteroseptum. In one case with valvular disease a false positive result was obtained at posterior wall where neither myocardial necrosis nor fibrosis was observed at autopsy. This case had aortic stenosis due to bicuspid aortic valve by autopsy. The ventricle was divided into 16 segments in each of 4 short axial images to evaluate extent of MI. SPECT for extent of MI showed sensitivity of 81.9%, specificity of 96.0% and diagnostic accuracy of 92.5%. False negative segment was apt to be observed at the surrounding of non-transmural MI or basal half of left ventricle (LV) with transmural MI, while false positive segment was at posterior portion of basal half of LV. It was concluded that myocardial ECT was useful for evaluation of the site and extent of MI.     

Anodic stripping voltammetric determination of bismuth(III) using a Tosflex-coated mercury film electrode

A Tosflex-mercury film electrode (TMFE) was prepared by spin-coating a solution of the perfluorinated anion exchange polymer Tosflex onto a glassy carbon electrode surface followed by electrodeposition of mercury film on this electrode. This electrode was used for the determination of trace bismuth(III) which was preconcentrated onto the TMFE as anionic bismuth(III) complexes with chloride in a chloride medium. The preconcentration was carried out at a potential of-0.2 V, and the preconcentration of the bismuth(III) was enhanced significantly by the anion-exchange feature of Tosflex. The accumulated bismuth(III) was then determined by anodic square-wave stripping voltammetry (SWSV). Various parameters influencing the determination of bismuth(III) were examined in detail. With 2 min accumulation, the analytical signal versus concentration dependence was linear up to 50 ppb, and the detection limit was 0.58 ppb. This modified electrode showed good resistance to the interferences from surface-active compounds and common ions.     

Purification and characterization of befunolol reductase from rabbit liver

An enzyme (befunolol reductase) which catalyzes the reduction of befunolol to dihydrobefunolol was purified from the cytosolic fraction of rabbit liver to homogeneity by various chromatographic techniques. Befunolol reductase had molecular weights of 29000 on sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis and 34000 on gel filtration. The enzyme required reduced nicotinamide adenine dinucleotide phosphate (NADPH) as a cofactor and showed an optimal pH of 6.5. The apparent Km and Vmax values of the enzyme for the reduction of befunolol were 1.7 mM and 4.4 units/mg, respectively. Flavonoids, sulfhydryl reagents, heavy metals and coumarins strongly inhibited the enzyme. The enzyme catalyzed the reduction of a variety of aromatic ketones. In addition to befunolol, some ketone-containing drugs such as daunorubicin and levobunolol were efficiently reduced by the enzyme. On the basis of substrate specificities for steroids, befunolol reductase purified from the cytosolic fraction of rabbit liver appeared to be a 3 alpha-hydroxysteroid dehydrogenase.