Normal Phase High Performance Liquid Chromatography of Some Prostaglandin B1 Derivatives

Abstract

15-Keto-13, 14-trans-prostaglandin B₁ methyl ester, 13,14-trans-prostaglandin B₁ methyl ester, 13,14-cis-prostaglandin B₁ methyl ester, 13,14-dihydro-prostaglandin B₁ methyl ester and 13,14-dehydro-prostaglandin B₁ are organic intermediates used in the synthesis of prostaglandin B_x, a polymeric derivative of 15-keto-prostaglandin B₁ methyl ester. PGB_x has been shown to protect laboratory animals against cardiogenic shock, cerebral ischemia and hypoxia. A normal phase, high performance liquid chromatographic analysis is presented which permits the identification and quantitation of these PGB₁ intermediates.     

The polarity of polyoxyethylene glycol dialkyl ethers and their sulphur analogs as measured by parameters considering intermolecular electric interactions

Summary The new stationary phase polarity parameters B_N and B_S evaluated from the concept of the electric intermolecular interactions are used to describe the polarity of polyoxyethylene glycol dialkyl ethers and their sulphur analogs. Relations between the discussed parameters and accepted measures of surfactants' polarity are presented and discussed. The considered parameters are correlated with the compound structures. Structural increments for characteristic fragments of the molecule are calculated and use to predict B_N and B_S values.     

Non-radiative decay of the benzene 1B2u and 3B1u states

Optic-acoustic measurements on high pressure benzene are presented, and are used to analyse the nature of the decay channels form the highly vibrationally excited ³B_1u state. The vibrationally relaxed benzene ³B_1u state is deactivated by n-pentane with a collisional efficiency of 3 × 10^?5. A model, introducing an intermediate state close in energy to the ³B_1u state, is shown to be in good accord with the results.     

Superhard boron suboxide (B6O): Crystal structure,synthesis, properties,applications, and materials based thereon

A review of reported data on the crystal structure, synthesis, and properties of boron suboxide B₆O, which is a superhard material (hardness of up to 55 GPa, as measured in single crystals), and composites based on it is presented. Methods for the synthesis of B₆O with a icosahedral structure and for the growing of crystals at high temperature and high pressure are described. The mechanical and operational characteristics of composite materials based on B₆O are summarized; the resistance of B₆O to oxidation is analyzed, and the properties of B₆O–diamond and B₆O–B₄C composite materials are described.     

On the analog of benzene B6H 6 n ? , 2 ≤ n ≤ 6: Geometry of B6H 6 n ? anions

The possibility of existence of the B₆H ₆ ⁶⁻ anion as the analog of the benzene molecule with a planar structure was considered. It was shown that on addition of two electrons to the [B₆H ₆ ⁴⁻ (O _h )] anion, the change from the octahedral to the planar geometry and the formation of B₆H ₆ ⁶⁻ (C _6v ) is thermodynamically unfavorable. The lithium ions in Li₆B₆H₆ can be used as the stabilizing coordination factor in the anion. The occurrence in the B₆H ₆ ⁿ⁻ ions (n = 2−6) of the shared π-electrons responsible for the formation of the highly aromatic systems with the planar geometry was shown to be impracticable. Original Russian Text ? N.T. Kuznetsov, S.P. Ionov, 2007, published in Koordinatsionnaya Khimiya, 2007, Vol. 33, No. 10, pp. 738–741.     

A theoretical study on the ionization of tetrafluoroethylene with analysis of vibrational structure of the photoelectron spectra

Ab initio calculations have been performed to study on the molecular structures and the vibrational levels of the low-lying ionic states (²B_2u,²A_g,²B_2g,²B_3u,²A_u,²B_1g,²B_1u, and²B_3g) of tetrafluoroethylene. The equilibrium molecular structures and vibrational modes of these states are presented. The theoretical ionization intensity curves including the vibrational structures of the low-lying eight ionic states are also presented and compared with the photoelectron spectrum. Some new assignments of the photoelectron spectra are proposed.     

Understanding the Central Location of a Hexagonal Hole in a B36 Cluster

The most stable form of a B₃₆ cluster has a central hexagonal hole. Such an interesting finding has led to the possible synthesis of a 2D boron sheet by employing the B₃₆ cluster as the building unit. Herein, a DFT study to investigate the reason for the central location of the hexagonal hole in the B₃₆ cluster is presented. The results show that the B₃₆ cluster with a central hexagonal hole is highly thermodynamically and kinetically stable. More importantly, such high stability is further understood through chemical bonding analysis.     

Quantum chemistry study on B32 and B32H2–32

The structures of B32 and B₃₂H^2–₃₂ with I_h symmetry have been investigated by means of ab initio calculations at STO-3G level. The relationship between molecular orbitals of them has been analyzed and their bonding properties have been discussed. Then the possibility of their existence, as well as the similarity and difference between B₃₂ (B₃₂H^2–₃₂) and C₆₀ (C₆₀H₆₀) have been inferred.     

Preparation process of a highly resistant wollastonite bioceramics using local raw materials

Wollastonite (CaSiO₃) is mainly used for traditional ceramics. In this study, wollastonite-based ceramics was obtained by solid state reaction. The starting powders were sintered at different temperatures (850–1,250 °C) for 2 h. Moreover, different amounts of B₂O₃ (0.5–5.0 mass%) have been added. A relative density of about 97% of the theoretical was reached for samples sintered at 1,050 °C for 2 h, containing 3 and 5 mass% B₂O₃. Excellent values of both three point flexural strength (343 ± 34 MPa) and micro-hardness (4.8 GPa) for samples containing 5 mass% B₂O₃, sintered at 1,050 °C for 2 h. Besides this, a relatively low mass loss ratio has been measured (1.1%) for wollastonite samples containing 5 mass% B₂O₃, sintered under the same conditions, after soaking in lactic acid for 9 days. Finally, the bioactivity of wollastonite by the possibility of formation of apatite on the surface of wollastonite immersed in simulated body fluid was confirmed.     

On line trace enrichment for isolation of vitamin B2 in food samples

Summary Vitamin B₂ was enriched by liquid-solid extraction from large volumes of aqueous samples on a short precolumn. The enriched compounds were transferred onto an analytical reversed-phase column and separated by ion-pair chromatography. The equipment used provides the possibility of automation for routine analysis.Dedicated to Professor J. F. K. Huber on the occasion of the 60th birthday.     

AFB1–AP Conjugate for Enzyme Immunoassay of Aflatoxin B1 in Corn Samples

Abstract

This article describes the conjugation between aflatoxin B₁ (AFB₁), one of the major mycotoxins, and alkaline phosphatase (AP), one of the most used enzymes for immunoassays. In addition, an application of the ELISA method for aflatoxin B₁ determination in corn is presented. Three AFB₁–AP conjugates in different toxin–enzyme ratios were prepared and tested. The ELISA results, developed with the most effective conjugate obtained, showed a satisfactory working range between 2.4 and 4000 ng of toxin/g of corn. The detection limit was 2 ng/g in corn samples, and recoveries ranged from 105 to 120%.     

Molecular recognition phenomena in polyelectrolyte systems

The term “molecular recognition” is commonly used to describe various specific interactions, sometimes being not well defined. Let's assume that some species A can separately interact with either species B₁, or B₂, (or B₃, B₄ etc.) forming A·B₁, or A·B₂, (or A·B₃, or A·B₄ etc.) complexes. Here we say “recognition” assuming selective complexation of A with B₁ in the mixture containing also B₂ (B₃, B₄… etc.). At the same time it means discrimination of all other B species except B₁.     

Indirect Determination of Organic Compounds by Atomic Absorption Spectrophotometry: The Study of Vitamin B12 in Pharmaceutical Dosage Forms

Abstract

A method for the determination of vitamin B₁₂ in pharmaceutical dosage forms is presented. The method involves, dissolution of the vitamin B₁₂ and subsequent determination of the complexed cobalt by atomic absorption spectrophotometry. The method is both rapid and sensitive giving applications to quality, control of this type of formulation.     

Determination of B-group vitamins in Turkish honey using ultra-performance liquid chromatography with electrospray ionization coupled to tandem mass spectrometry

A rapid and sensitive ultra-performance liquid chromatography–tandem mass spectrometry method with electrospray ionization (UPLC–ESI–MS/MS) for analysis of B-group vitamins in honey has been presented. Aim of this study is the characterization of different types of Turkish honeys according to B-group vitamins. Vitamins were determined in 17 different types of Turkish honey samples by UPLC–ESI–MS/MS. Heather honey samples were distinguished among the studied honeys with the richest vitamin content with 286.10?mg/kg, and it is followed by sunflower honey and thyme honey with the total vitamin contents of 206.01 and 163.27?mg/kg, respectively. The presence of vitamin B₁ (thiamine), vitamin B₂ (riboflavin), vitamin B₃ (nicotinamide, B₃N and nicotinic acid, B₃H), vitamin B₆ (pyridoxine), and vitamin B₉ (folic acid) was detected in all the honey samples analyzed. Moreover, vitamin B₅ (pantothenic acid) was observed in most of them. Vitamin B₁₂ (cyanocobalamin) and vitamin B₇ (biotine) were not detected in the studied honey samples. Turkish honey samples showed efficacious vitamin content for the consumers.     

Location of the first 3B2 ← 3B+2 transition in phenanthrene

The polarization of the triplet-triplet absorption spectrum of phenanthrene-d₁₀ in the region from 3500 to 8500 A has been recorded. The ³B₂^? state is located at about 4250 Å. The possibility that phenanthrene might be a suitable chromophore for laser dye synthesis is discussed.     

Organometallic B12–DNA Conjugate: Synthesis,Structure Analysis,and Studies of Binding to Human B12‐Transporter Proteins

Design, synthesis, and structural characterization of a B₁₂‐octadecanucleotide are presented herein, a new organometallic B₁₂–DNA conjugate. In such covalent conjugates, the natural B₁₂ moiety may be a versatile vector for controlled in vivo delivery of oligonucleotides to cellular targets in humans and animals, through the endogenous B₁₂ transport systems. Binding of the organometallic B₁₂ octadecanucleotide to the three important human proteins of B₁₂ transport was studied, to examine its structural suitability for the task of eventual in vivo oligonucleotide delivery. Binding was efficient with transcobalamin (TC), but not so efficient with the homologous glycoproteins intrinsic factor and haptocorrin. Binding of the B₁₂ octadecanucleotide to TC suggests the capacity of the B₁₂ moiety to serve as a natural vector for specific transport of single stranded, organometallic oligonucleotide loads from the blood stream into cells.     

The binary system composed of a bent-core compound forming a B7 phase and a nematogenic calamitic compound

The isobaric phase diagram for a binary system of liquid crystals is presented. One mixing component is a bent-core mesogen forming a B₇ phase and the other one is a nematogenic calamitic compound. The occurring mesophases have been identified by their optical textures as well as by X-ray investigations. The B₇ phase exists down to about 60 mol% of the bent-core compound A / 40 mol% of the calamitic compound B. Two additional mesophases are induced in the mixed phase region. At medium concentrations (around 50 mol%) an oblique columnar phase appears which shows a similar X-ray pattern to the B₇ phase but an utterly different nucleation on cooling the isotropic liquid and a completely dissimilar texture. At concentrations below 35 mol% A, a further phase is induced which possesses an irregularly modulated layer structure. This phase can be regarded as an intermediate state between the regularly modulated Col_r (B₁) phase and the intercalated B₆ phase. It transforms on cooling into the phase with a regularly modulated structure.     

Supertetrahedrane and its boron analogs

Novel stable structures, viz., supertetrahedrane (C₁₀₄H₃₂), supertetraborane (B₁₀₄H₃₂), and mixed supertetracarboranes (B₆₄C₄₀H₃₂ and B₄₀C₆₄H₃₂), derived by substituting for carbon atoms in the diamond lattice by tetrahedra C₄ and B₄, respectively, and being supermolecular models of the corresponding carbon and boron crystalline structures were studied by the DFT B3LYP/6-311+G** method. The low difference in energies of the frontier orbitals indicate semiconduction properties of these compounds. The carbon-carbon, boron-boron, and carbon-boron bonds in the studied compounds are shorter than in diamond and in the borane or carboranes systems, respectively. Along with the calculated vibrational spectra, this indicates that their mechanical properties are similar to those of diamond. However, a considerably low density of these compounds shows their high potential possibility of applying them in aerospace technology.     

New details in the polarized spectrum of naphthalene by means of linear dichroism studies in oriented polymer matrices

Linear dichroism (LD) spectra are presented for naphthalene oriented in stretched polyethylene and polypropylene matrices at 77 K and 296 K. From the calculated spectrum LD(λ)/A(λ), where A(λ) is the corrected absorbance spectrum of the sample by unpolarized light, orientational parameters are calculated and component spectra, 235–315 nm, are resolved corresponding to polarization parallel to the long (B_3u = x) and the short (B_2u = y) axes in the molecular plane (D_2h). The orientational parameters indicate different orientational mechanisms in polyethylene and polypropylene, but the resolving procedure yields mainly identical component spectra. It is suggested that the polarization (B_3u) predominating in the 245–275 nm region isdue to a B_1g vibronic perturbation of the ¹B_2u state.     

Validation of a screening method for the simultaneous identification of fat-soluble and water-soluble vitamins (A,E, B<Subscript>1</Subscript>, B<Subscript>2</Subscript> and B<Subscript>6</Subscript>) in an aqueous micellar medium of hexadecyltrimethylammonium chloride

Simultaneous determination of the fat-soluble vitamins A and E and the water-soluble vitamins B₁, B₂ and B₆ has been carried using a screening method from fluorescence contour graphs. These graphs show different colour zones in relation to the fluorescence intensity measured for the pair of excitation/emission wavelengths. The identification of the corresponding excitation/emission wavelength zones allows the detection of different vitamins in an aqueous medium regardless of the fat or water solubility of each vitamin, owing to the presence of a surfactant which forms micelles in water at the used concentration (over the critical micelle concentration). The micelles dissolve very water insoluble compounds, such as fat-soluble vitamins, inside the aggregates. This approach avoids the use of organic solvents in determining these vitamins and offers the possibility of analysing fat- and water-soluble vitamins simultaneously. The method has been validated in terms of detection limit, cut-off limit, sensitivity, number of false positives, number of false negatives and uncertainty range. The detection limit is about g L^–1. The screening method was applied to different samples such as pharmaceuticals, juices and isotonic drinks.