Determination of nafcillin and methicillin by different spectrofluorimetric techniques

In order to explore the possibilities of combining synchronous fluorescence and derivative spectrometry and to establish a methodology for this type of technique, nafcillin and methicillin were determined using these techniques. Several methods for resolving binary mixtures of these penicillins using first derivative spectrofluorimetry, first derivative constant wavelength synchronous luminescence spectrometry and constant energy synchronous luminescence spectrometry are described. The analyses were performed in aqueous medium at pH 6.20 provided by the addition of phosphate buffer solution. A complete and exhaustive statistical analysis of the experimental data was performed to demonstrate the validity of these methods, which obtained good results when applied for determining nafcillin and methicillin synthetic and real mixtures.     

Zur Analytik der Pyridoxine

4 selective tests for pyridoxal and pyridoxamine are described. In combination with the test by means of 2,6-dichloroquinone-4-chloroimine it is possible to determine pyridoxol, pyridoxamine and pyridoxal in presence of each other in mixtures. It is shown that the three components are able to be transformed into one another.     

大气气溶胶中多环芳烃的特征光谱检测技术研究

采用紫外-可见分光光度法、傅立叶红外光谱法和恒能量同步荧光分析法进行实验室模拟测试,检测蒽、苯并[a]芘、荧蒽、苯并[k]荧蒽、苯并[ghi]苝5种多环芳烃(PAHs),对比分析了各检测技术的灵敏度、精密度、检出限、线性范围、混合组分图谱分离度等指标。结果表明,恒能量同步荧光法的选择性最好,灵敏度(0.046 0~1.360 5Io.ng-1)和精密度(平均空白的RSD为4.1%)均最高,检出限(0.038~0.427μg.L-1)最低,线性范围较宽(0.126~7 157μg.L-1),是3种光谱分析法中最适合无分离在线检测气溶胶中多组分PAHs的方法。将该方法应用于实际大气环境气溶胶样品中各PAHs成分的定性鉴别和定量检测,5种PAHs均被检出,各物质的特征峰分离效果好,峰形明显,能满足实际测量的分析要求。     

固定能量同步发光光谱测定法

本文介绍一种分子发光分析新技术——固定能量同步发光光谱测定法(CESLS)。该法系在激发波长和发射波长的同时扫描过程中保,持两者间有一个固定的能量差。它具有比经典发光分析法和固定波长同步发光光谱测定法更为优越的特点,是一种有潜力的多组分分析方法。尤其在PAHs分析中,可望获得广泛应用。本文还讨论了CESLS参数选择的理论优化问题。     

Three-dimensional total synchronous luminescence spectroscopy criteria for discrimination between normal and malignant breast tissues

Specimens of malignant and normal female human breast tissues were analyzed after surgery by means of synchronous luminescence spectroscopy. Measurements were performed in the ranges of excitation wavelengths from 330 to 650 nm and synchronous wavelengths from 30 to 120 nm to obtain ordinary and first derivative three-dimensional total synchronous luminescence spectra (3d-TSLS) of each specimen. Arithmetic mean of these spectra has been calculated for normal and malignant specimens and analyzed to establish criteria for tissue differentiation. Spectral domain volumes (volumes below luminescence intensity surface) and mean spectral slopes have been calculated and also analyzed as tissue discrimination criteria. The obtained results are discussed in view of the possible relevance of synchronous luminescence spectroscopy in discrimination between normal and malignant breast tissue.     

Low-temperature constant energy synchronous luminescence spectroscopy

Constant energy synchronous luminescence spectroscopy is extended to low temperature conditions for the determination of polynuclear aromatic hydrocarbons. Low-temperature constant energy synchronous luminescence spectroscopy implements a constant energy difference between monochromators as each is scanned through the spectral region of interest. The major advantage of this development is the optimization of parameter selection used in each determination. While this investigation was performed at 77 K, theoretical considerations are extended to 4 K conditions. Application to multicomponent samples is also demonstrated.     

Recent advances and future prospects in fluorescence and phosphorescence spectroscopy

Various approaches which manipulate the physical and chemical microenvironment of lumiphors are outlined and examples given of surfactant, microcrystalline and cyclodextrin molecular organization. These methodologies can give improved selectivity, and in some cases, enhanced fluorescence and/or phosphorescence intensities. Complimentary methods of generating luminescence via targeted energy transfer, namely, sensitized room temperature phosphorescence and chemiluminescence, are briefly discussed. The power of non-clasical luminescence techniques to produce more useful analytical results is illustrated for micelle-enhanced/sensitized room temperature phosphorescence, a liquid chromatographic/micelle-stabilized phosphorescence detector, and synchronous wavelength scanning/second derivative/micelle-stabilized phosphorescence. The combination of computer-assisted instrumentation and organized chemical microenvironments to obtain the total luminescence spectral profile should provide attomolar sensitivities, and selectivity without prior separation of mixtures on a more routine basis in the near future.     

Simultaneous determination of warfarin and bromadiolone by derivative synchronous fluorescence spectrometry

By using second derivative synchronous fluorescence spectrometry the simple resolution of mixtures of the anticoagulant rodenticides warfarin and bromadiolone in the presence of beta-cyclodextrin is accomplished which causes a differential effect on the fluorescence intensity of these compounds. The determination method developed is simple, fast and inexpensive; in addition, measurements are performed in a single scan. Mixtures of warfarin and bromadiolone in ratios between 4:1 and 1:10 were satisfactorily resolved.     

Zur Analytik der Pyridoxine

Zusammenfassung Es werden 4 spezifische Nachweis- und Bestimmungsreaktionen für Pyridoxal und Pyridoxamin mitgeteilt. In Kombination mit dem Nachweis mit Gibbss'chem Reagens können nunmehr Pyridoxol, Pyridoxal und Pyridoxamin in Gemischen nebeneinander bestimmt werden. Die Überführbarkeit der 3 Komponenten ineinander wird aufgezeigt.

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On the analysis of pyridoxins

4 selective tests for pyridoxal and pyridoxamine are described. In combination with the test by means of 2,6-dichloroquinone-4-chloroimine it is possible to determine pyridoxol, pyridoxamine and pyridoxal in presence of each other in mixtures. It is shown that the three components are able to be transformed into one another.

     

Kinetic and mechanism of reactions of L-α-Glutamic acid and L-Glutamine with pyridoxal

The kinetics and mechanisms of condensation of pyridoxal with L-α-glutamic acid and L-glutamine were studied by UV spectroscopy and polarimetry. L-α-Glutamic acid reacts with pyridoxal to form a Schiff base whose subsequent hydrolysis gives rise to pyridoxamine and α-ketoglutaric acid. The reaction of Lglutamine with pyridoxal involves the Γ-NH₂ group and affords a Schiff base whose subsequent hydrolysis gives rise to pyridoxamine and L-α-glutamic acid.     

Constant-energy synchronous, time-resolved, room-temperature phosphorimetry

The combination of constant-energy synchronous luminescence spectrometry (CESL) with a pulsed source and gated detection is used to demonstrate the analytical power of time resolution CESL in room-temperature phosphorimetry. The instrumentation is discussed. Two binary mixtures are evaluated to demonstrate the spectral simplification of this technique.     

The use of synchronous luminescence spectroscopy in qualitative analysis of aromatic fraction of hard coal thermolysis products

The synchronous luminescence method was used in qualitative analysis of aromatic fraction of low-temperature tar from hard coal. The spectra obtained by this method are simpler than spectra obtained with the use of conventional emission luminescence method. The synchronous luminescence analysis requires the selection of respective Deltalambda parameter values. This parameter is a constant difference between position of excitation and emission monochromators during measurement. From literature, the Deltalambda parameter value of 23 nm was first used here. The characteristic emission ranges of spectra obtained indicated (by comparison with spectra of standards) degree of condensation of aromatic compounds present in investigated mixtures. It was also possible to identify some individual compounds. However, this identification could be more effective with the use of the respective value of Deltalambda parameter for each particular component of the mixture. This manner of analysis was used here, e.g. for investigating aromatic fraction containing phenanthrene (identified previously by gas chromatography method) among other compounds. The spectrum recorded at Deltalambda value characteristic for phenanthrene (53nm) presents a rather simple shape with a maximum at 346 nm attributed to phenanthrene after standard and literature data.     

Gasoline and crude oil fingerprinting using constant energy synchronous luminescence spectrometry

Constant energy synchronous luminescence spectrometry (CESLS) is applied to environmental analysis involving gasoline and crude oil samples containing polyaromatic hydrocarbons (PAHs). Sample identification at low temperature (77 °K) with quartz tubes and room temperature on filter paper is performed. The ability to identify individual PAHs in samples as well as fingerprint different samples based on total PAH content with CESLS is demonstrated.     

Chemical transformations of the condensation products of pyridoxal with L-α-alanine and D-α-alanine

The kinetics and mechanism of the reactions of pyridoxal with L- and D-α-alanine were studied. Under comparable conditions, the condensation of L- and D-α-alanines with pyridoxal includes three kinetically different steps. The first fast step is addition of the amino acid to pyridoxal with formation of the corresponding amino alcohol, the second (slower) step is dehydration of the amino alcohol to give Schiff base, and the third (very slow) step is elimination of α-hydrogen atom from the L-α-amino acid fragment or decarboxylation of the D-α-amino acid fragment, followed by isomerization of the Schiff base to quinoid structure whose subsequent hydrolysis yields pyridoxamine and pyruvic acid or acetaldehyde, respectively. A scheme was proposed for chemical transformations of the pyridoxal condensation products with L- and D-α-alanines.     

Pyridoxamine,a scavenger agent of carbohydrates

Pyridoxamine has been found to inhibit protein glycation and to avoid the formation of advanced glycation end‐products (AGEs). One of the mechanisms by which pyridoxamine can inhibit glycation involves the scavenger of carbonyl groups with glycation capacity. In this work, we conducted a kinetic study of the reactions of pyridoxamine with various carbohydrates under physiological pH and temperature. The reactions involving hexoses were found to give a tricyclic compound ( 5 ) in addition to pyridoxal and pyridoxine. Such a tricyclic compound inhibits the Amadori rearrangement and the formation of other carbonyl compounds with glycating properties. The reactions involving pentoses gave compound 7 and pyridoxal—by transamination of the Schiff base. The transamination reaction enhances the inhibitory action of pyridoxamine. The formation rate constants for the Schiff base, k₃, were found to be similar to those for the reactions of D ‐glucose with amino acids, which suggests competition between pyridoxamine and terminal amino residues in proteins for glycating sites in sugars. These constants are dependent on the electrophilic character of the carbonyl carbon in the carbohydrate. © 2007 Wiley Periodicals, Inc. 39: 154–167, 2007     

Vitamin b6 analogs

The synthesis of 2- and 5-modified analogs of pyridoxine from which analogs of pyridoxal and pyridoxal 5-phosphate were obtained is described. The transition to analogs of pyridoxamine and pyridoxamine 5-phosphate is realized by hydrogenation of the oximes of these aldehydes.See [1] for communication XV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 655–660, May, 1974.     

采用高效液相色谱技术分析生物体内维生素B6

维生素B6(VB6)是一类2-甲基-3-羟基吡啶类化合物的总称，基本类型有吡哆醇(PN)、吡哆醛(PL)和吡哆胺(PM)，磷酸酯型有磷酸吡哆醇(PNP)、磷酸吡哆醛(PLP)和磷酸吡哆胺(PMP)，其中磷酸吡哆醛和磷酸吡哆胺为活性形式，是多种酶的辅酶，哺乳动物尿中VB6的代谢产物主要是不具有生理活性的吡哆酸(PIC)，在植物体内还发现有数种吡哆醇的糖衍生物和氨基酸衍生物。     

Resolution of ternary mixtures of salicylic, salicyluric and gentisic acids by partial least squares and principal component regression: Optimization of the scanning path in the excitation-emission matrices

The resolution of ternary mixtures of salicylic, salicyluric and gentisic acids has been accomplished by partial least squares (PLS) and principal component regression (PCR) multivariate calibration. The total luminescence information of the compounds has been used to optimize the spectral data set to perform the calibration. A comparison between the predictive ability of the three multivariate calibration methods, PLS-1, PLS-2 and PCR, on three spectral data sets, excitation, emission and synchronous spectra, has been performed. The excitation spectrum has been the best scanning path for salicylic and salicyluric acid determinations, while the emission spectrum has been the best for the gentisic acid determination. The convenience of analysing the total luminescence spectrum information when using multivariate calibration methods on fluorescence data is demonstrated.     

Chemical transformations of pyridoxal and pyridoxal 5′-phosphate condensation products with amino acids

The mechanism of chemical transformations of pyridoxal and pyridoxal 5′-phosphate condensation products with amino acids is studied by kinetic measurements. The Schiff bases are shown to be fairly stable in neutral media. In acid media, the Schiff bases are hydrolyzed into the initial components. In alkaline media, cleavage of α-hydrogen from the amino acid fragment and structural rearrangement into the quinoid form followed by hydrolysis of the latter with elimination of pyridoxamine and keto acid take place. The rate constants of the chemical transformations of the Schiff bases are found to depend on the pH of the medium. It is shown for the first time that the phosphate group in the pyridoxal 5′-phosphate fragment catalyzes the α-hydrogen cleavage and strongly accelerates alkaline decomposition of the Schiff bases.     

Spectrophotometric determination of ternary mixtures of thiamin, riboflavin and pyridoxal in pharmaceutical and human plasma by least-squares support vector machines.

Ternary mixtures of thiamin, riboflavin and pyridoxal have been simultaneously determined in synthetic and real samples by applications of spectrophotometric and least-squares support vector machines. The calibration graphs were linear in the ranges of 1.0 - 20.0, 1.0 - 10.0 and 1.0 - 20.0 microg ml(-1) with detection limits of 0.6, 0.5 and 0.7 microg ml(-1) for thiamin, riboflavin and pyridoxal, respectively. The experimental calibration matrix was designed with 21 mixtures of these chemicals. The concentrations were varied between calibration graph concentrations of vitamins. The simultaneous determination of these vitamin mixtures by using spectrophotometric methods is a difficult problem, due to spectral interferences. The partial least squares (PLS) modeling and least-squares support vector machines were used for the multivariate calibration of the spectrophotometric data. An excellent model was built using LS-SVM, with low prediction errors and superior performance in relation to PLS. The root mean square errors of prediction (RMSEP) for thiamin, riboflavin and pyridoxal with PLS and LS-SVM were 0.6926, 0.3755, 0.4322 and 0.0421, 0.0318, 0.0457, respectively. The proposed method was satisfactorily applied to the rapid simultaneous determination of thiamin, riboflavin and pyridoxal in commercial pharmaceutical preparations and human plasma samples.