分光光度法测定盐酸多巴胺的含量

研究了氨水溶液中,FeCl3与盐酸多巴胺反应生成紫红色络合物,其最大吸收波长为507 nm,络合比为1∶2.体系的吸光度与盐酸多巴胺的浓度在20.0～220 mg/L范围内呈良好的线性关系,线性回归方程A=0.00842+0.11844 ρ(mg/L),相关系数r=0.9991,表观摩尔吸光系数ε=2.25×104L·...     

利用荷移反应分光光度法测定针剂中的多巴胺

研究了多巴胺与四氯苯醌之间的荷移反应，测量络合物组成比为１：１，摩尔吸光系数ε＝１．６３＊１０＾３。方法的相对标准偏差为１．２％。应用据说 定方法测定物制剂中多巴胺含量与药典方法一致，回收率在９４．５％－１０２％。     

荧光光度法测定多巴胺

多巴胺（ＤＭ）与Ｔｂ＾３＋在ＰＨ０．５￣６．８条件下形成较强的荧光络合物,基ｎｍ,发射峰在４９４ｎｍ和５４５ｎｍ处,多巴胺在６．０×１０６－７￣４．７×１０＾－５ｍｏｌ／ｌ范围内与共 光强度呈线性关系;检测限为３．２×１０＾－７ｍｏｌ／Ｌ,将其用于样品中多巴胺的回收实验,结果令人满意。     

测定葡萄糖的简易分光光度法

研究发现葡萄糖与磷钼杂多酸反应 ,能生成有色产物 ,它的最大吸收波长是 690 nm,吸光度与葡萄糖的质量浓度呈线性关系 ,检出限为 2× 1 0 -5mol/L。本法已用于测定葡萄糖注射液中的葡萄糖含量。     

紫外分光光度法间接测定果冻中甜蜜素

提出了紫外分光光度法间接测定食品中甜蜜素的方法。考察了酸性介质的种类,亚硝酸钠与碘化钾浓度、用量及反应时间对测定的影响。在优化的试验条件下,甜蜜素在1.0～14.0mg·mL-1范围内遵守比耳定律,检出限(3S/N)为0.3mg·mL-1。用此方法测定果冻中甜蜜素含量,加标回收率为102.6%～103.3%,相对标准偏差(n=5)为0.7%～1.3%。     

分光光度法测定甲醛

重点论述了各种测定甲醛的分光光度法的现状及其改进,目前存在的不足之处及面临问题,同时展望了该法的前景。     

紫外分光光度法测定丙酮酸

基于丙酮酸在紫外吸收光谱290～340nm区有较强的吸收,建立了分光光度法测定丙酮酸(盐)的方法。在pH11．0的水溶液中,位于320nm处,丙酮酸有吸收,而其他有机酸和杂质无吸收或吸收不明显。在320nm处,丙酮酸在0．2～2．8g／L范围内符合比耳定律,其R2为0．9997,平均回收率99．8％,RSD0．46％。该法适合于发酵液和分离提取过程中丙酮酸及其盐类的测定。     

硫酸根的分光光度法测定

本文就硫酸根的间接及直接光度测定的基本原理，试剂，方法和应用等作了较为系统的评述。列出重要文献６７篇。     

分光光度法测定头孢氨苄

头孢氨苄与茚三酮在酸性水溶液中能发生显色反应。表观摩尔吸光系数为是７．９５×１０＾３Ｌ．ｍｏｌ＾－１．ｃｍ＾－１。作者详细研究了该反应的条件，应用拟定的方法测定药物制剂含量与药典方法一致，回收率在９９％以上。     

Spectrophotometric determination of dopamine in microliter scale using microfluidic system based on polymeric technology

In this paper we report two simple and sensitive spectrophotometric procedures for the determination of dopamine in microfluidic system based on poly(dimethylsiloxane) (PDMS) technology and comparison of their interference-susceptibility. The analytical reactions and measurements were carried out at ambient temperature in a microreactor of total volume 6 μl coupled with a spectrophotometric flow-through cuvette.     

Spectrophotometric determination of dopamine in pharmaceutical formulations

A new spectrophotometric method was developed for the estimation of dopamine. The method is based on the bromination of the dopamine with a solution of excess brominating mixture. After bromination, the excess brominating mixture is treated with potassium iodide to produce a yellow solution. The absorbance of yellow solution was measured at 350 nm on a Spectronic 1001 spectrophotometer against distilled water as a blank.From Zhurnal Analiticheskoi Khimii, Vol. 60, No. 3, 2005, pp. 2842285.Original English Text Copyright © 2005 by Rami Reddy, Sreedevi, Prabhavathi, Chakravarthy.This article was submitted by the authors in English.     

Spectrophotometric determination of some antipsychotic phenothiazines

Thioridazine hydrochloride reacts with sodium nitrite and antimony(III) potassium tartrate in the presence of hydrogen peroxide to give a yellowish orange colour having maximum absorbance at 420 nm. The reaction is specific for antipsychotic phenothiazines with 1 g/ml as visual limit of identification and provides a basis for a new Spectrophotometric determination. The colour reaction obeys Beer's Law from 0.01 to 1.25 mg/10ml thioridazine. The standard deviation does not exceed 0.050 mg/10 ml. The method is successfully applied to pure and pharmaceutical preparations of antipsychotic phenothiazines, as well as to urine samples. The quantitative assessment of tolerable amounts of other drugs is also studied.     

Sodium dodecyl sulfate-modified electrochemical paper-based analytical device for determination of dopamine levels in biological samples

We report the development of an electrochemical paper-based analytical device (ePAD) for the selective determination of dopamine (DA) in model serum sample. The ePAD device consists of three layers. In the top layer, SU-8 photoresist defines a hydrophilic sample application spot on the filter paper. The middle layer was made from transparency film and contained two holes, one for sample preconcentration and the other for the surfactant to allow transfer to the third layer. A screen-printed carbon electrode formed the bottom layer and was used for electrochemical measurements. In the absence of the anionic surfactant, sodium dodecyl sulfate (SDS), the oxidation peaks of DA, ascorbic acid (AA) and uric acid (UA) overlapped. With the addition of SDS, the DA oxidation peak shifted to more negative values and was clearly distinguishable from AA and UA. The oxidation potential shift was presumably due to preferential electrostatic interactions between the cationic DA and the anionic SDS. Indeed, whilst the SDS-modified paper improved the DA current five-fold, the non-ionic Tween-20 and cationic tetradecyltrimethylammonium bromide surfactants had no effect or reduced the current, respectively. Furthermore, only the SDS-modified paper showed the selective shift in oxidation potential for DA. DA determination was carried out using square-wave voltammetry between −0.2 and 0.8 V vs. Ag/AgCl, and this ePAD was able to detect DA over a linear range of 1–100 μM with a detection limit (S/N = 3) of 0.37 μM. The ePAD seems suitable as a low cost, easy-to-use, portable device for the selective quantitation of DA in human serum samples.     

Sodium dodecyl sulfate-modified carbon paste electrodes for selective determination of dopamine in the presence of ascorbic acid

A carbon paste electrode (CPE) modified by a monolayer film of sodium dodecyl sulfate (SDS) was used for detection of dopamine (DA). Cyclic voltammetry demonstrated improved response of the DA sensor. This suggests the effectivity of surface modification of CPE by SDS. Impedance spectroscopy was used for the characterization of CPE surface properties. The effect of SDS concentration on the electrode quality also reveals that SDS formed a monolayer on CPE surface with a high density of negative-charged end directed outside the electrode. As a result, the carbon paste electrode modified with SDS (SDS/CPE) exerted discrimination against ascorbic acid in physiological circumstance. Thus, it can selectively determine dopamine even in the presence of 220-fold AA combined with differential pulse stripping voltammetry. In pH 7.40 phosphate buffer solution, the oxidation peak current on differential pulse voltammograms increases linearly with the concentration of DA in the range of 5.0 x 10(-7) to 8.0 x 10(-4) mol . L(-1) with a detection limit of 5.0 x 10(-8) mol . L(-1). Satisfying results are achieved when detecting the DA in injection and simulated biology sample.     

流动注射协同化学发光法测定盐酸多巴胺

基于在碱性介质中,盐酸多巴胺和单宁协同促进KIO4氧化鲁米诺反应而产生发光,建立了流动注射化学发光法测定盐酸多巴胺的新方法。该方法测定盐酸多巴胺的线性范围为2.0×10-10～6.0×10-8g/mL,检出限为1.17×10-10g/mL,对于8.0×10-10g/mL盐酸多巴胺测定11次的相对标准偏差为1.92%。方法可应用于盐酸多巴胺注射液和尿样中盐酸多巴胺的测定。     

辣根过氧化物酶功能化金簇用于多巴胺的测定

制备了辣根过氧化物酶功能化金簇,在弱碱性介质中,激发波长和发射波长为425 nm/628 nm;过氧化氢能够使得金簇荧光发生猝灭,在体系中加入适量多巴胺,荧光猝灭程度减弱,且减弱程度与加入多巴胺的量呈正比;多巴胺在0.04～8.0μmol/L内呈线性,其线性回归方程为:AF= 10.01 +43.28c(μmol/L)...     

Flow injection fluorescence determination of dopamine using a photo induced electron transfer (PET) boronic acid derivative

An automated flow injection analysis system was developed for the fluorometric determination of dopamine in pharmaceutical injections. The method is based on the quenching effect of dopamine on m-dansylaminophenyl boronic acid (DAPB) fluorescence due to the reverse photo induced electron transfer (PET) mechanism. Effects of pH and interfering species on the determination of dopamine were examined. Calibration for dopamine, based on quenching data, was linear in the concentration range of 1.0 × 10⁻⁵ to 1.0 × 10⁻⁴ M. Detection limit (3 s) of the method was found to be 3.7 × 10⁻⁶ M. Relative standard deviation of 1.2% (n = 10) was obtained with 1.0 × 10⁻⁵ M dopamine standard solution. The proposed method was applied successfully for the determination of dopamine in pharmaceutical injection sample. The sampling rate was determined as 24 samples per hour.     

Graphene-loaded nanofiber-modified electrodes for the ultrasensitive determination of dopamine

A novel and highly sensitive electrochemical system based on electrospun graphene/polyaniline/polystyrene (G/PANI/PS) nanofiber-modified screen-printed carbon electrodes has been developed for dopamine (DA) determination. A dramatic increase (9 times) in the current signal for the redox reaction of a standard, ferri/ferrocyanide [Fe(CN)₆]^3−/4− couple was found when compared to an unmodified electrode. This modified electrode also exhibited favorable electron transfer kinetics and excellent electrocatalytic activity toward the oxidation of DA. When used together with square wave voltammetry (SWV), DA can be selectively determined in the presence of the common interferents (i.e. ascorbic acid and uric acid). Under optimal conditions, a very low limit of detection (0.05 nM) and limit of quantification (0.30 nM) were achieved for DA. In addition, a wide dynamic range of 0.1 nM to 100 μM was found for this electrode system. Finally, the system can be successfully applied to determine DA in complex biological environment (e.g. human serum, urine) with excellent reproducibility.     

Voltammetric determination of dopamine in the presence of ascorbic and uric acids using partial least squares regression: determination of dopamine in human urine and plasma

A new differential pulse voltammetric method for dopamine determination at a bare glassy carbon electrode has been developed. Dopamine, ascorbic acid (AA) and uric acid (UA) usually coexist in physiological samples. Because AA and UA can be oxidized at potentials close to that of DA it is difficult to determine dopamine electrochemically, although resolution can be achieved using modified electrodes. Additionally, oxidized dopamine mediates AA oxidation and the electrode surface can be easily fouled by the AA oxidation product. In this work a chemometrics strategy, partial least squares (PLS) regression, has been applied to determine dopamine in the presence of AA and UA without electrode modification. The method is based on the electrooxidation of dopamine at a glassy carbon electrode in pH 7 phosphate buffer. The dopamine calibration curve was linear over the range of 1–313 μM and the limit of detection was 0.25 μM. The relative standard error (RSE %) was 5.28%. The method has been successfully applied to the measurement of dopamine in human plasma and urine.