Sorption-spectrophotometry and chromaticity determination of some organic bases used in local anesthesia using Alizarin Red C

The use of 1,2-dihydroxyanthraquinone-3-sulfonic acid sodium salt, Alizarin Red C (ARC), is considered in application to the sorption-spectrophotometry determination of organic bases novocaine and lidocaine, used as local anesthetics. The optimal conditions for the formation of all adsorbates are deter-mined, and the equations depicting the relation between the chromaticity functions (CFs) and concentration of organic bases are found. As shown, ARC absorbs chemically on the surface of γ-Al₂O₃ as ions with the charge 2- with a predominantly vertical orientation. The calculated molar coefficients of sorbates’ CFs are 200 times hugher than the ones for respective extracts. Based on the developed procedures, color scales for the rapid testing of analytes are developed. The potential use of the procedures elaborated is discussed.     

Effects of lidocaine on the expansion of lipid monolayer at air/water interface in relation to the local anesthesia

Lidocaine compounds have widely been used as local anesthetics. Regarding the molecular mechanism for anesthesia by local anesthetics, two hypotheses have been proposed. The first one is that molecules of local anesthetics penetrate into the hydrophobic region of cell membrane and expand the membrane volume, resulting in a change of protein conformation that blocks sodium permeability. The second hypothesis is that molecules of local anesthetics are directly adsorbed into the receptors of anesthetics in the protein channel without expanding the cell membrane. However, these proposals have never been examined systematically. In this study, the expansion of cell membrane by lidocaine compounds was investigated by employing lipid monolayer at the air/water interface as the mimetic system for cell membrane. It was found that oil-soluble lidocaine contracted the area/molecule of lipids in the monolayer of phosphatidyl choline, sphingomyelin, DS-PL95E and lipoid, but expand the monolayer of phosphatidyl ethanolamine only in a certain range of mixing ratios. Thus, this study can provide an evidence that lidocaine yields anesthesia effect by adsorbing into receptors in the protein channel rather than expanding the cell membrane.     

3,4,5-Trihydroxyfluorones as analytical reagents

Acid-base, spectrophotometric, and chromaticity characteristics of 3,4,5-trihydroxy-9-(2′-sulfophenyl)-6-isoxanthone (Pyrogallol Red, PR) and its 2,7-dibromo derivative (Dibromopyrogallol Red, BPR) were considered. The effect of the ionic strength, solvents, and surfactants on these characteristics was discussed. The complexation of the reagents with metal ions in the presence of second and third components (surfactants of different natures and organic reagents) was considered. The analytical characteristics of two-, three-, and four-component complexes were compared. The selectivity of the reagents, methods for changing the selectivity, and applications in analytical chemistry were considered. It was noted that chromaticity measurements are promising for studying the complexation of ions and their determination.     

铅的吸光光度法测定研究进展

作者从分离、富集、掩蔽方法与光度测定的结合,以及一些Pb(Ⅱ)的重要显色剂出发对Pb(Ⅱ)的吸光光度测定的近年进展作了评述(引用文献58篇).     

Analysis of pharmaceutical preparations containing local anesthetics by micellar liquid chromatography and spectrophotometric detection

Summary An HPLC procedure for the determination of six local anesthetics, bupivacaine, lidocaine, mepivacaine, procaine, propanocaine and tetracaine, in pharmaceutical silane ODS-2 C₁₈ analytical column and spectrophotometric detection at 230 nm were used. The chromatographic tographic behaviour of local anesthetics with different micellar eluents of sodium dodecyl sulphate (SDS) is described. Selection of the adequate composition of the micellar mobile phase (SDS and 1-propanol concentrations) for the analysis of pharmaceuticals was studied. Adequate retention was achieved with an eluent containing 0.15 M SDS +10% 1-propanol at pH 3. Application of the proposed method to the analysis of eight pharmaceutical formulations gave recoveries between 93 and 100.2% of the values declared by the manufacturers. The proposed procedure for the determination of local anesthetics is rapid, reliable and free from interferences.     

Test films for test-determinations on the base of reagents, immobilized in gelatinous gel

Gelatinous solidified layers of the photographic film were used for the immobilization of analytical reagents for detection and determination of reductants and primary aromatic amines. It was shown, that the films with immobilized iron(III)-Dipy or iron(III)-Phen complexes as test films for reductants and films with immobilized aldehydes (vanillin, p-dimethylaminobenzaldehyde) as the test films for primary aromatic amines can be used. The improving of reagents immobilization in the presence of sodium dodecylsulfate micelles was obtained. Metrological characteristics of visual detection and photometric determination using test films were evaluated on the basis of statistical approach and investigation of detection probability distribution in the concentration range of unreliable reaction. The suggested test films for the determination of ascorbic acid, analgin (dipyrone), novocaine and streptocide in drugs were examined successfully.     

Electroanalytical Determination of Lidocaine in Pharmaceutical Preparations Using Boron‐Doped Diamond Electrodes

A new electroanalytical procedure was developed for the determination of lidocaine in commercial local anesthetics products containing lidocaine as the active ingredient. The procedure is based on the use of electrochemical methods as cyclic and square‐wave voltammetry, with boron‐doped diamond electrodes. The oxidation of lidocaine in Britton–Robinson buffer (0.1 mol L^?1) using this type of electrode gives rise to one irreversible peak in 1.68 V (versus Ag/AgCl). The detection and quantification limits obtained from pure water were 10.0 and 34.4 μg/L, respectively. The proposed electrochemical method was also successfully applied to the analysis of commercially available pharmaceutical preparations. The electrochemical responses of pharmaceutical preparations (gels) were identical to those of standard lidocaine. No influence of propyleneglycol present in the gels on the voltammetric responses was observed. Lidocaine recoveries ranged from 97.6% to 99.2%.     

流动注射-共振瑞利散射法测定某些局部麻醉药物

在稀盐酸介质中, 12-钨磷酸(TP)分别与丁卡因(TC)、普鲁卡因(PC)和利多卡因(LC)等局部麻醉药反应形成离子缔合物, 导致溶液的共振瑞利散射(RRS)显著增强. 它们的最大RRS峰位于345 nm(TP-TC), 368 nm(TP-PC)和379 nm(TP-LC), 并且在一定范围内, 麻醉药的浓度与散射强度呈线性关系, 据此建立流动注射-共振瑞利散射联用技术测定丁卡因、普鲁卡因和利多卡因的新方法, 不同麻醉药的检出限在0.5~9.5 ng/mL之间. 以灵敏度最高的丁卡因为例, 试验了共存物质的影响及分析应用, 表明方法具有良好的选择性和较高的重复性; 用于尿样中TC的测定, 加标回收率为98.8%~103.2%; 对于质量浓度为2.0 μg/mL的TC进行9次平行测定的相对标准偏差为1.7%; 进样频率为60 h-1. 采用量子化学AM1法计算了3种药物的电荷分布, 并从药物结构差异上讨论了反应机理.     

Toxicity and local anesthetic activity of diterpenoid alkaloids

The toxicity and local anesthetic activity of 74 diterpenoid alkaloids differing in the nature and position of functional groups in lycoctonine, heteratisine, napelline, hetisane, atisane, and denudatine skeletons and their synthetic derivatives were investigated. Compounds with local anesthetic activity and duration of action surpassing that of cocaine for surface anesthesia and that of novocaine and lidocaine for infiltration and trunk administration were identified. Structural factors affecting the toxicity and local anesthetic activity of the studied compounds were discussed. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 477–484, September–October, 2007.     

Determination of amino acids, vitamins, and drug substances in aqueous solutions using new potentiometric sensors with Donnan potential as analytical signal

Basic principles of a new potentiometric sensor are considered. Its analytical signal is the Donnan potential at the ion-exchange polymer/studied solution of electrolyte interface. Assessments of potential drops at individual interfaces are presented, same as estimates of diffusion potentials in the electrochemical circuit for measurement of the sensor response. It is shown that the overall contribution of the values of all potentials to EMF of the electrochemical circuit, except for the Donnan potential, at the ion-exchange polymer/studied solution interface are negligibly low as compared to the experimental values of the circuit EMF in the studied systems. Certain regularities of the Donnan potential formation are studied in the systems with the polymers of different structure and solutions containing inorganic ions and organic electrolytes in different ionic forms. The possibility is shown of using a sensor with such an analytical signal as the Donnan potential for assay of amino acids, vitamins, and drug substances in aqueous solutions. The sensor was used as a selective electrode for determination of lysine in aqueous solutions with neutral amino acids in the range of pH 5.0–7.0 and glycine in aqueous alkali solutions in the range of pH 9.00–11.00. The developed sensor is introduced as a cross-sensitive electrode into the array of multisensor systems for multicomponent quantitative analysis of the lysine monohydrochloride, thiamine chloride, novocaine hydrochloride, lidocaine hydrochloride solutions containing potassium and sodium chlorides. The measurement error of electrolytes in aqueous solutions did not exceed 10%.     

Artificial and natural fiber fabrics with immobilized reagents in chemical test methods of analysis

Fabric matrices made of viscose and cotton fiber with adsorption-immobilized organic reagents are considered with respect to their possible use for chemical test methods of analysis. Triarylmethane, thiazine, eurhodine, acridine, azo, and diazo compounds are used for immobilization. It is found that the degree of reagent retention (R, %) depends on the pH and the type of the matrix used. R varies within 12–99%. The absorption spectra of the reagents immobilized on fabric matrices exhibit hypsochromic or bathochromic shifts of absorption bands (2–45 nm as compared to their absorption spectra in solution). As a rule, the degree of retention is higher for the reagents that exhibit a shift of the absorption band on the support. The adsorption isotherms of the reagents on various cellulose supports are analyzed. Test procedures are developed for the determination of antimony and mercury using modified fabric matrices. The rapidity, precision, and sensitivity of previously developed procedures for the test determination of Cu(II), Cd, and S^2? are improved. The relative standard deviations of the determinations are no more than 0.1; the analysis time is 5–10 min.     

Ion-Selective Electrodes for the Determination of Nitrogen-Containing Medicinal Substances

Stoichiometric ratios and solubility products were determined for medicinal substance–tetraphenyl borate ion pairs. The influence of the nature of the medicinal substance cation incorporated into ionophores and the effect of the solvent–plasticizer on analytical characteristics were studied. The optimal composition of membranes was determined. Ion selective electrodes were used for the potentiometric determination of dimedrol, papaverine, novocaine, and lidocaine in medicinal forms.     

Highly efficient proteinase assay with chromogenic substrates and its application in a study of enzyme inhibitors

A simple and rapid method for the determination of enzyme activities with chromogenic substrates is described. Trypsin and papain were used as model proteinases and N-benzoyl-dl-arginine p-nitroanilide (BAPNA) was applied as substrate. The enzyme assay was performed on a multi-scale using 96-well microtitration plates and product release was detected with the aid of an automatic plate reader, widely used in ELISA tests. The procedure was used for electrophoretic studies of trypsin and a crude papain preparation. It was also applied for the investigation of N-peptidyl-O-acylhydroxylamine proteinase inhibitors. In comparison with commonly used procedures with chromogenic substrates, the proposed approach consumes markedly reduced amounts of all reagents. It allows an almost unlimited number of samples to be assayed in a short time and should be applicable to the detection and determination of any enzyme activitiy where chromogenic substrates are applicable.     

Application of the H-point standard addition method to the speciation of Fe(II) and Fe(III) with chromogenic mixed reagents

Simultaneous determination of Fe(II) and Fe(III) or selective determination of each oxidation state of iron in the presence of the other one by H-point standard addition method (HPSAM) is described. Mixed reagents of 1,10-phenanthroline and salicylic acid was used as a selective chromogenic system for speciation of Fe(II) and Fe(III). It was shown that with appropriate selection of wavelength pairs, both Fe(II) and Fe(III) can be considered as analyte. The results showed that Fe(II) and Fe(III) can be determined simultaneously with the concentration ratios of Fe(II) to Fe(III) varying from 10:1 to 1:20 in the mixed sample. The accuracy and precision of the method are all satisfactory.     

Chemical approach to ill-conditioned calculation problems in spectrophotometry

Multiple-component determinations present difficulties which cannot be resolved mathematically when there is severe spectral overlap, as in the determination of rare-earth elements with chromogenic reagents. The interdependence of absorptivities is greatly decreased when absorbance data from procedures based on several chromogenic reagents are used together in the calculations of calibration factors and concentrations. Various features of the method are discussed.     

Spectrophotometric Methods for Determining Noble Metals

The main trends of the development of spectrophotometric methods for determining noble metals (NMs) are considered. One of these trends is the synthesis and study of new, highly sensitive and selective organic reagents for determining NMs in solutions and in solid phase. Another trend is the search for and development of new methodological approaches (techniques) and color reactions, including those that involve modified and immobilized reagents. The third trend includes the improvement of equipment and automation in FIA, CFA, derivative, rapid-scanning, and multiwavelength spectrophotometry. It also implies a new generation of instruments measuring the absorbance and reflectance of solid materials modified with organic reagents and with their NM complexes; microwave energy sources for the dissolution of samples, preparation of test solutions, and activation of photometric reactions; and multioperational analytical moduli for autoclave sample preparation with resistive heating. The present-day spectrophotometry can provide the determination of NMs in samples with concentrations from several to 10^–4% (photometry and differential photometry) and down to 10^–7% (test and sorption–spectroscopic methods based on photometry and diffuse-reflectance spectroscopy, including the use of chromaticity functions).     

Difference in surface activities between uncharged and charged local anesthetics: correlation with their anesthetic potencies

The surface activities of six uncharged local anesthetics, dibucaine (DC), bupivacaine (BC), lidocaine (LC), mepivacaine (MC), benzocaine (BzC), and benzyl alcohol (BzOH) were investigated by taking surface tension measurements of their aqueous solutions. The surface densities of the uncharged anesthetics were calculated from the application of thermodynamic equations to the surface tension data. The surface activities for uncharged anesthetics became higher in the order of their hydrophobicities, BzOH相似文献   

Designing Medical Devices Based on Silicon Polymeric Material with Controlled Release of Local Anesthetics

The drug delivery systems that are the object of this article take the form of a polymer matrix made of silicone containing a drug. These devices can be used as patches for local dermal applications releasing the drug in a controlled manner. The model active agent, lidocaine hydrochloride was chosen from the range of local anesthetics. When the drug is restricted to the surface, it is released more rapidly than when it is allowed to spread evenly throughout the silicon structure. When hydrophilic polymers such as PVA and HEC are mixed in with the lidocaine hydrochloride and deposited on the surface of the polymer matrix, we observed that the burst effect was eliminated without modifying the overall quantity of lidocaine hydrochloride released.     

Determination of novocaine in pharmaceutical preparations with novocaine(+)-selective membrane electrodes

Liquid-membrane ion-selective electrodes made with the ion-association complexes of novocaine with tetraphenylborate or dipicrylamine are proposed for use in the determination of novocaine by direct potentiometry or by potentiometric titration with sodium tetraphenylborate. The titration method is preferred, and the mean relative error for 4-12 mg of novocaine hydrochloride is 0.5%.     

Application of Alizarine Derivatives as Chromogenic Reagents for the Spectrophotometric Determination of Some Sulfa Drugs

A spectrophotometric procedure for the determination of six pharmaceutical sulfonamides containing a primary aromatic amino group using alizarine (I), alizarine blue (II), alizarine red (III), and quinalizarine (IV), that offers advantages of simplicity, rapidity, sensitivity, precision, and stability, has been developed. The proposed method is based on the formation of colored products with the chromogenic reagents (I-IV). A linear correlation was found between absorbance at λ_max and the concentration. For more accurate results, Ringbom optimum concentration ranges are evaluated. The molar absorptivities (ε), absorptivities (a), and Sandell sensitivities for all sulfonamides derivatives with the chromogenic reagents tested were calculated. The procedures developed are applied for bulk sulfa drugs and some of their dosage forms.