Determination of Vanadium with Chlorosubstituted Hydroxamic Acids for Photometric and Atomic Absorption Spectrophotometric Determination

Abstract

The eight newly synthesized chlorosubstituted hydroxamic acids are described for the extraction and spectrophotometric determination of vanadium. The sensitive and selective reagent, N-m-Chlorophenylpalmito hydroxamic acid, (m-CPPHA), which gives violet coloured vanadium complex was extracted with chloroform from 6M HCl. The violet coloured complex thus obtained has a maximum absorbance at 520 nm and molar absorptivity 4.9 ± 10³1mol^?1cm^?1. The Beer's law obeyed in the region 0.50-12.0ppm. Effects of acidity, reagent concentration, diverse ions have also been investigated. A comparison has been made with atomic absorption spectrophotometric method. Vanadium has been determined in the environment, e.g. plant, soil, rock, etc.     

一种分析磷及其磷化物的新方法

测定固、液相样品中磷及其化合物的新方法是将待测样品中的磷及其化合物分解并被原子氢还原为ＰＨ３，再用气相色谱仪测定。该方法不需化学预处理，快速、灵敏、可靠，测定结果与分光光度法基本一致。     

萃取-催化氧化光度法测定H2O2的羟基自由基 (Ⅱ)

利用混合稀土与微量过氧化氢催化氧化二苯基碳酰肼，建立了萃取－催化氧化光度法测定过氧化氢的羟基自由基的新方法，该法具有仪器简单，体系稳定，操作方便等优点，非常适合于筛选羟基消除剂。     

GLC and Colorimetric Methods for the Determination of Capsaicin

Abstract

GLC and colorimetric methods for Capsaicin and its dosage forms are investigated. They offer an improvement in ease, speed and accuracy. The first GLC method is based on the formation of methyl derivative of capsaicin. The colorimetric procedure is based on the formation of O-nitroso-derivative between the drug and sodium nitrite.     

时间分辨后化学发光同时测定林可霉素和卡那霉素

根据林可霉素、卡那霉素在过氧化单硫酸盐(PMS)-鲁米诺(Luminol)体系中的化学发光反应动力学性质的明显差异,建立了时间分辨后化学发光同时测定林可霉素和卡那霉素的新方法.在PMS-鲁米诺体系中林可霉素化学发光反应较快,0.8s达到最大值,峰尖锐;卡那霉素化学发光反应较慢,54.8s后达到最大值,峰平缓,且其动力学曲线呈现出随时间分开的两个独立的发光峰,互不干扰.该方法测定林可霉素、卡那霉素的线性范围分别为4.0×10-9～8.0×10-7 g/mL、4.0×10-7～8.0×10-5 g/mL,对8.0×10-8 g/mL的林可霉素溶液和8.0×10-6 g/mL的卡那霉素溶液进行测定,其相对标准偏差(RSD,n=11)分别为4.6％和3.3％,测定林可霉素和卡那霉素的检出限分别为1.0×10-9 g/mL和1.0×10-7 g/mL.     

Dopant-stimulated CuO Nanofibers for Electro-oxidation and Determination of Glucose

We described the preparation of copper oxide composite nanofibers doped with carbon nanotubes (CuO/C-NFs) or nickel oxide(CuO/NiO-NFs) by electrospinning for direct glucose determination. The interest in exploring practical CuO/C-NFs and CuO/NiO-NFs electrode materials for sensor application was fascinated by the possibility of promoting electron transfer for kinetically unfavorable glucose oxidation reactions at a lower overpotential and thus improving the selectivity of the electrode for glucose in electroanalysis. The morphologies of CuO/C-NFs and CuO/NiO-NFs were characterized by scanning electron microscopy(SEM) and X-ray powder diffraction(XRD). The electrocatalytic performances of glucose were evaluated in detail by cyclic voltammetry(CV) and chronoamperometry. Facile charge transport, enhanced current response(at a lower overpotential of +0.35 V), improved stability and selectivity, as well as excellent resistance towards electrode fouling were observed at CuO/ C-NFs electrode in direct glucose electroanalysis. These merits are attributed to the highly porous three-dimensional network film structure of CuO/C-NFs electrode materials and the potential synergic catalytic effect of CuO and carbon nanotubes in composite nanofibers. This study may provide a new insight into metal oxide-based composite nanofibers obtained via electrospinning for fabricating novel and high performance sensors and devices.     

Aptamer Biosensor for Selective and Rapid Determination of Insulin

Insulin plays an important role in glucose metabolism and its detection in biological fluids is of interest. In this study, a triple-helix molecular switch was employed for the simple, sensitive, and rapid determination of insulin. The triple-helix molecular switch was composed of a target specific aptamer sequence flanked by two arm segments and a dual-labeled oligonucleotide acting as a signal transduction probe. This approach takes advantage of unique properties of aptamers and triple-helix molecular switches such as high affinity, selectivity, and stability. In the absence of insulin, the fluorescence of triple-helix molecular switch is on. Upon addition of insulin, the aptamer binds to its target, leading to the release of the signal transduction probe, folding of the signal transduction probe to a stem loop structure, and the quenching of the fluorescence. This sensor showed a high selectivity toward insulin and a limit of detection as low as 9.97 nM. The sensor was employed for the determination of insulin in biological samples. This platform may be generalizable for a variety of molecules.     

New Ion-Selective Electrodes for Determination of Bupivacaine and Oxybuprocaine

Abstract

PVC membrane electrodes selective for hydrochlorides of the anaesthetics bupivacaine (BpC) and oxybuprocaine (ObC) are prepared. The electrodes have a near Nernstian slope (58 mV for BpC and 51 mV for ObC electrodes) over the range of 1.6 × 10^?5-10^?1M and 1.3 × 10^?1M for BpC and ObC electrodes, respectively. The change in pH of the test solution within the ranges 2.5–6.0 and 3.0–7.4 does not affect the EpC-and ObC-electrodes, respectively. The electrodes have very long life times (10 days for BpC, and 3 months for ObC) and exhibit good seletivity for the investigated compounds with respect to a large number of inorganic cations and organic substances of biological importance. The isothermal coefficients of the electrodes are calculated from the standard electrode potentials at different temperatures. BpC and ObC are determined successfully in some pharmaceutical preparations using the calibration graph technique and potentiometric titration.     

Derivatization of Xanthomegnin for Fluorometric Determination

Abstract

A derivatization procedure was developed for the fluorometric determination of purified xanthomegnin. A highly fluorescent product is formed by reaction of xanthomegnin with ammonia and hydrogen peroxide under defined conditions. The derivative is a light brown compound that can easily be dissolved in water or polar organic solvents. Its excitation and emission wavelengths in methanol are 340 and 445 nm, respectively. As little as 0.1 ng of xanthomegnin can be detected using high pressure liquid chromatography in a reverse phase system with fluorescence detection.     

流动注入式乳酸生物传感器

研制了一种测定L－乳酸的生物传感器,将乳酸氧化酶（LOD）通过共价键固定在尼龙钢上制备乳酸氧化酶膜,将制得的酶膜固定在氧电极上构成乳酸生物传感器;将透析膜放在氧化酶膜上产生对L－乳酸扩散高度限制来改变该生物传感器的响应;酶膜机械强度高,在氧电极上反复装卸而不损坏,所构成的乳酸生物传感器的校正曲线的乳酸定量上限达5mmol/L,响应时间小于30s;初步血样测试的结果显示该乳酸生物传感器用于临床血乳酸的测定具有可行性。     

Liposome Immunoassay for Determination of Phenytoin

Inthispaper,arapid,sensitive,andsimpleliposomeimmunoassay(LIA)lbrdetectingphenytoinhasbeenestablished.Phenytoinisuscdtocurecpilepsy,butinclinicalpractice,theefficientconcentrationofphenytoininpatient'sseraisverynarrow,about1O~2Opg/ml.Iftheconcentrationofphenytoininserumislessthantheefficientconcentration,thereisnoeffectofmedicine.Butiftheconcentrationrangewerc2O~4Ollg/ml,themedicinecouldbringsideeffect.Ifthcconcentrationbecomesgreater,thenitcancausepoisoning.Becausetherearemanyfactorswhich…     

测定核黄素的化学发光新方法

研究了核黄素的化学发光性质，建立了一种测定核黄素的化学发光新方法，并应用于实际样品中核黄素的测定，与文献相比，本方法无需避光，而且分析体系和样品处理简单；干扰小，牛血清白蛋白、抗坏血酸、天冬氨酸等８种生物有机物质和 Ｃｕ（Ⅱ）、Ｚｎ（Ⅱ）、Ｆｅ（Ⅲ）等１５种常见金属离子的允许量较大；核黄素溶液浓度在０． １０～５０ ｍｇ／Ｌ范围内，与化学发光强度成正比，方法线性范围宽；测定１．０ｍｇ／Ｌ核黄素溶液１２次，求得相对标准偏差为２．９％，方法精密度高；方法的检测限为０．０７５ ｍｇ／Ｌ，灵敏度高。     

Utility of Fluoranil for Spectrophotometric Determination of Griseofulvin and Dexamethasone

Abstract

Two important drugs griseofulvin and dexamethasone have been quantitatively estimated through complexation with fluoranil (tetrafluoro-2,5-cyclohexadiene - 1,4- dione). The optimal experimental conditions, applicability of the suggested method to assay the cited drugs in their tablet forms, and statistical analysis of the results were studied. The results obtained were compared with those of the corresponding official method of assay for each drug, showing good agreement with the official methods. Furthermore, the reaction products have been isolated and subjected to structure elucidation by means of IR-Spectroscopic technique.     

一种快速廉价的蛋白质测定方法

蛋白质测定的Ｌｏｗｒｙ法显色反应在３０℃以下通常需３０ｍｉｎ,Ｌａｒｓｏｎ利用加入二硫苏糖醇（ＤＴＴ）使反应快速完成并提高了灵敏度,但存在ＤＴＴ价格昂贵的不足。利用连二亚硫酸钠（保险粉）代替ＤＴＴ,实现了蛋白质含量快速、灵敏、廉价的测定。     

First Report for Electrochemical Determination of Levodopa and Cabergoline: Application for Determination of Levodopa and Cabergoline in Human Serum,Urine and Pharmaceutical Formulations

The electrochemical oxidation of levodopa on the surface of a carbon paste electrode modified with graphene nanosheets, 1‐(4‐bromobenzyl)‐4‐ferrocenyl‐1H‐[1,2,3]‐triazole (1,4‐BBFT) and hydrophilic ionic liquid (n‐hexyl‐3‐methylimidazolium hexafluoro phosphate) as a binder is studied. It has been found that the oxidation of levodopa at the surface of a modified electrode occurs at a potential of about 210 mV less positive than that of an unmodified carbon paste electrode (CPE). The prepared modified electrode exhibits a very good resolution of the voltammetric peaks of levodopa and cabergoline. The electrode has been applied successfully for the determination of levodopa and cabergoline in some real samples.     

Use of Catecholoxygenase for Determination of Catechol

Abstract

A cell extract from Trichosporon cutaneum containing catechol 1,2-oxygenase catalyzes the oxidation of catechol to cis,cis-muconic acid. The absorbance of the cis,cis-muconic acid at 260 nm can be correlated with the initial catechol concentration in the range 5 × 10^?6 M to 5 × 10^?5 M in aqueous solutions. This enzymatic assay has been applied to the determination of catechol in aqueous samples derived from coal processing.     

Amperometric and Conductimetric Methods for Simultaneous Determination of Captopril and Bendroflumethiazide

Abstract

The mixture of captopril (antihypertensive) and bendroflumethiazide (diuretic) was assayed using conductimetric and amperometric methods. Each method was applied for the analysis of laboratory-made sample mixtures in authentic and dosage forms. For captopril, the amperometric and conductimetric methods gave mean percent recoveries of 100.2 ± 1.2 and 99.6 ± 1.2, respectively. These results have shown good agreement when compared with other methods in the literature. When applied to bendroflumethiazide the conductimetric method gave percent recovery of 98.5 ± 1.6 which agreed closely with the spectrophotometric pharmacopoeial method.

The pK₁ for captopril was determined potentiometrically at room temperature (25°C) in aqueous medium. The calculated value, based on Henderson equation was 3.78.     

Optimized Method for the Determination of Flavonoid Glycosides and Aglycones

The relationship R_M=f (log % S; S- modifier) of several flavonoids and their sugar derivatives was examined by using chromatographic systems chosen by preliminary experiments. The dependence for flavonoid aglycones was flat in the whole mobile phase concentration. Two types of the R_M=f (log % S) plots, related to the size of sugar molecule, were found. For glycosides with smaller sugar moiety (arabinose or glucose) the plot was almost parallel, while plots of derivatives with larger sugar moiety (rutose) were convergent. After plotting the relationship R_M=f (log % S), even if standards are not available, it is possible to qualify the examined compound as containing single or complex sugar moiety. For all mentioned above compounds the R_M=f (log %S) values were given. Silica gel Si60 was used as polar adsorbent. Mobile phase composition was determined in preliminary experiments; it was composed of two solvents: methanol in ethyl acetate in increasing concentration of methanol: 5 – 20%.     

P－矩阵荧光法同时测定苯酚和十二烷基苯磺酸钠

在研究了苯酚(Ph-OH)和十二烷基苯磺酸钠(SDBS)荧光性质的基础上,以P-矩阵计算混合体系中苯酚和十二烷基苯磺酸钠。方法灵敏度高,选择性好,简便快速,应用于环境水样测定结果令人满意。     

Validated HPLC Method for Separation and Determination of Terbutaline Enantiomers

Abstract

A simple, rapid, and validated method for separation and determination of terbutaline enantiomers was developed. Terbutaline was separated and determined on a Vancomycin Chirobiotic V column (250 × 4.6 mm), using a mixture of methanol, acetic acid, and triethylamine (100:0.1:0.1% v/v/v) as a mobile phase at 20°C and at a flow rate of 1 ml/min. The UV detector was set to 276 nm. Acetyl salicylic acid (aspirin) was used as an internal standard. The applied high-performance liquid chromatography (HPLC) method allowed separation and quantification of terbutaline enantiomers with good linearity (r > 0.999) in the studied range. The relative standard deviations (RSD) were 1.10 and 1.32% for the terbutaline enantiomers with accuracy of 99.80 and 99.55. The limit of detection and limit of quantification of terbutaline enantiomers were found to be 0.05 and 0.10 µg · ml^?1, respectively. The method was validated through the parameters of linearity, accuracy, precision, and robustness. The HPLC method was applied for the quantitative determination of terbutaline in pharmaceutical formulations.