Spectrophotometric Determination of Water-Soluble Hexavalent Chromium and Determination of Total Hexavalent Chromium Content of Portland Cement in the Presence of Iron (III) and Titanium (IV) Using Derivative Ratio Spectrophotometry

A rapid, reliable and accurate method for the determination of hexavalent chromium in Portland cement is developed. The proposed method includes direct spectrophotometric determination of Cr (VI) in Portland cement with 1, 2, 5, 8 Tetrahydroxyanthraquinone, (Quinalizarin, QINZ) at pH 1.5. The European Directive (2003/53/EC) limits the use of cements so that it contains no more than 2 mg.Kg-1 of water-soluble Cr (VI). The absorbance at 565 nm due to Cr (VI)-QINZ complex is recommended for the determination of water-soluble Cr (VI) in Portland cement. The quantification of Cr (VI) released from cement when mixed with water is performed according to TRGS 613 (Technical Rules of Hazardous Substances). The validity of the method is thoroughly examined and the proposed method gives satisfactory results. A derivative spectrophotometric method has been developed for the determination of total Cr (VI) in Portland cement in the presence of Fe (III) and Ti (IV). The hexavalent chromium complex formed at pH 1.5 allows precise and accurate determination of chromium (VI) over the concentration range 0.05 to 3.0 mg.L-1of chromium (VI). The validity of the method was examined by analyzing several Standard Reference Material (SRM) Portland cement samples. The MDL (at 95% confidence level) was found to be 25 ng/mL for chromium (VI) in National Institute of Standards and Technology (NIST) cement samples using the proposed method.

A Dual Wavelength Differential First Derivative Spectrophotometric Method for Identification and Determination of Carbon Monoxide Generated During the Microsomal Metabolism of Xenobiotics in vitro

本文研究了双波长差示一阶导数分光光度法运用于作为对照品的一氧化碳（ＣＯ）饱和水浓度标定及定性与定量测定微粒体代谢中生成的一氧化碳的方法。本法的优点在于能显著消除试样本底干扰，大大提高了定量准确性及灵敏度。在ＣＯ浓度２～１０μｍｏｌ·Ｌ１范围内与导数光谱峰（４１５ｎｍ）和谷（４２６ｎｍ）之间距离（Ｄ）呈良好线性关系，ｒ＝０．９９９９（ｎ＝５），回归方程Ｃ（ｍｍｏｌ·Ｌ１）＝１７．６Ｄ０．４。最低检测浓度低于０．１μｍｏｌ·Ｌ１ＣＯ。系统回收率和加样回收率（Ｘ±ＲＳＤ）分别为１０２．１±２．９％（ｎ＝７）和７９．７±６．８％（ｎ＝１２）；日内、日间精密度（ＲＳＤ）分别为４．４％（ｎ＝１８）和６．１％（ｎ＝１６）。将本法用于４个三卤苯胺和一个三卤苯的体外代谢测定，结果表明，仅２，４，５三氟苯胺在体外能被大鼠肝微粒体、ＮＡＤＰＨ和分子氧代谢生成一氧化碳。苯巴比妥和地塞米松等肝药酶诱导剂能显著提高一氧化碳的代谢转化速率，它们分别为空白对照组的３或８倍。

Application of derivative ratio spectrophotometry for determination of β-carotene and astaxanthin from Phaffia rhodozyma extract

A derivative ratio spectrophotometric method was used for the simultaneous determination of β-carotene and astaxanthin produced from Phaffia rhodozyma. Absorbencies of a series of the standard carotenoids in the range of 441 nm to 490 nm demonstrated that their absorptive spectra accorded with Beer’s law and that the additivity when the concentrations of β-carotene and astaxanthin and their mixture were within the range of 0 to 5 μg/ml, 0 to 6 μg/ml, and 0 to 6 μg/ml, respectively. When the wavelength interval (?λ) at 2 nm was selected to calculate the first derivative ratio spectra values, the first derivative amplitudes at 461 nm and 466 nm were suitable for quantitatively determining β-carotene and astaxanthin, respectively. Effect of divisor on derivative ratio spectra could be neglected; any concentration used as divisor in range of 1.0 to 4.0 μg/ml is ideal for calculating the derivative ratio spectra values of the two carotenoids. Calibration graphs were established for β-carotene within 0?6.0 μg/ml and for astaxanthin within 0?5.0 μg/ml with their corresponding regressive equations in: y=?0.0082x?0.0002 and y=0.0146x?0.0006, respectively. R-square values in excess of 0.999 indicated the good linearity of the calibration graphs. Sample recovery rates were found satisfactory (>99%) with relative standard deviations (RSD) of less than 5%. This method was suc- cessfully applied to simultaneous determination of β-carotene and astaxanthin in the laboratory-prepared mixtures and the extract from the Phaffia rhodozyma culture.

Estimation of the galanthamine using derivative spectrophotometry in bulk drug and formulation

Two simple, rapid, accurate, precise, reliable and economical spectrophotometric methods have been proposed for the determination of galanthamine hydrobromide (GH) in bulk and pharmaceutical formulation. First method is zero order UV spectrophotometry and second is 1st derivative zero crossing spectrophotometry. The developed methods have shown best results in terms of linearity, accuracy, precision, LOD and LOQ for bulk drugs and marketed formulations. Absorbance was measured at 287 nm for zero order and 277.4 nm for first derivative. It obeyed Lambert-Beer’s law in the range of 30-80 μg mL-1. Both methods have good linearity (r2 = 0.9997) and accuracy found to be 100.5% and 101.2% for both methods respectively.

Studies on the Combined Derivative Spectrophotometry

The combined derivative spectrophotometry developed in this paper is a new method, which can be used to determine multicomporent mixture simultaneously and may improve the sensitivity and accuracy of the measurement remarkably. Two practical tests were carried out to verify the correctness of the theory, and the results are satisfactory.

A simple derivative spectrophotometric method for simultaneously detecting nitrate and nitrite in plasma treated water

A spectrophotometric technique is developed to simultaneously quantify nitrate and nitrite in plasma treated water.The measurement is based on examining the inflection points(wavelengths)in the derivative absorbance of the nitrate or nitrite solution.At the inflection points of the pure nitrate solution,the derivative absorbance is zero and independent of the nitrate’s concentration,and thus the nitrite’s concentration in a mixed nitrate and nitrite solution can be obtained by using the Beer’s law at these points.The nitrate’s concentration can also be achieved from the inflection points of nitrite in the same manner.The relation between the tested substance’s(nitrate or nitrite)concentration and the second-or the third-order absorbances is obtained at these inflection points.Test measurements for mixed aqueous solutions of nitrate and nitrite with or without hydrogen peroxide confirm the reliability of this technique.We applied this technique to quantify the nitrate and nitrite generated in air plasma treated aqueous solutions.The results indicate that both nitrate and nitrite concentrations increase with the plasma treatment time,and the nitrite species is found to be generated prior to the nitrate species in the air plasma treated aqueous solution.Moreover,the production rate of total nitrogen species is independent of the solutions’p H value.These results are relevant to diverse applications of plasma activated solutions in materials processing,biotechnology,medicine and other fields.

Fourth Derivative Spectrophotometric Method for the Determination of Fungicide Maneb Using Sodium Molybdate

A highly sensitive fourth derivative spectrophotometric method is presented for the residue analysis of ethylenebis dithiocarbamate fungicide Maneb. The fungicide maneb forms a blue complex with sodium molybdate on heating which is studied spectrophotometrically. The method has been successfully applied to maneb determination in wheat grains and soft drinks with high recoveries. The analytical sensitivity of the present method has been found to be 0.0011 μg/mL.

DIRECT DETERMINATION OF NEODYMIUM AND ERBIUM IN RARE EARTH MIXTURE BY DERIVATIVE SPECTROPHOTOMETRY

The absorption spectra of 4f electron transitions of the complexes of neodymium and erbium with 8-hydroxyquinoline-5-sulphonic acid in the presence of diethylamine and ethanol have been measured by normal and third-derivative spectrophotometry. Their molar absorptivities are 70.7 l.mol^(-1).cm^(-1) for Nd and 62.5 l.mol^(-1).cm^(-1) for Er. They are 7.6 times and 14.9 times greater than those of corresponding chlorides, respectively. Use of the third-derivative spectra both eliminates the interference of Ce(Ⅳ) and increases the sensitivity for Nd and Er. Beer,s Law was obeyed from 0-10 ug/ml of Nd and Er. The method has been applied to the determination of neodymium and erbium in rare earth mixtures.

Derivative Spectrophotometric and Isocratic High Performance Liquid Chromatographic Methods for Simultaneous Determination of Repaglinide and Metformin Hydrochloride in Pharmaceutical Preparations

In this study, a derivative spectrophotometric method and one HPLC method were developed and validated for analysis of anti-diabetic drugs, repaglinide (RPG) and metformine hydrochloride (MTF) in tablets. The spectrophotometric methods were based on zero-crossing first-derivative and fourth-derivative spectrophotometric method for simultaneous analysis of RPG (308 nm) and MTF (267 nm), respectively. Linear relationship between the absorbance at λmax and the drug concentration was found to be in the ranges of 5.0 - 50.0 μg·mL-1 for both RPG and MTF. The quantification limits for RPG and MTF were found to be 0.568 and 1.156 μg·mL-1, respectively. The detection limits were 0.170 and 0.347 μg·mL-1 for RPG and MTF, respectively. The second method is a rapid stability-indicating isocratic HPLC method developed for the determination of RPG and MTF. A linear response was observed within the concentration range of 5.0 - 50.0 μg·mL-1 for both RPG and MTF. The quantification limits for RPG and MTF were found to be 1.821 and 1.653 μg·mL-1, respectively. The detection limits were 0.601 and 0.545 μg·mL-1 for RPG and MTF, respectively. The proposed methods were successfully applied to the tablet analysis with good accuracy and precision.

Simple,Inexpensive and Ecologically Friendly Derivative Spectrophotometric Fluconazole Assay from Nail Lacquer Formulations

Nail lacquers represent new drug form specifically designed to treat infected nail plate. They are complex organic solutions with specific assaying problems due to the high content of the polymer and plasticizer. Furthermore, there is a lack of assaying methods of active substances from this type of formulations in scientific literature. We developed derivative UV-spectrophotometric method for determination of fluconazole content in antifungal nail lacquer formulations. The method was validated for specificity, linearity, precision (repeatability), intermediate precision and accuracy (recovery). The method is specific, linear in the range of 99.53 - 497.65 μg/ml, precise and showed good recovery (98.79% - 101.77% from all six developed formulations). Besides, it is inexpensive, simple and nontoxic, i.e. ecologically acceptable. This method can be used for assaying fluconazole from this type of formulations.

Simple and sensitive method for the determination of trace amounts of thorium using a benzoquinone derivative

A novel simple, sensitive, rapid, direct, and spectrophotometry-based procedure was investigated to determine Th(IV) at trace amounts. The new method is based on Th(IV) chelation with 3,6-dichloro-2,5-dihydroxy-l,4-benzoquinone(DDBQ). The reagent reacts with Th(IV) in 0.1 M HCl to form an orange 1:2 complex. The stability constant value is 6.62×10~4 for the Th(IV)complex. The Th(IV)-DDBQ obtained shows one peak with a maximum at about 346 nm. The chelate forms immediately and the absorbance remains stable for over24 h. Beer's law was obeyed in the concentration range0–10 μg mL^(-1). The molar absorptivity and Sandell's sensitivity were 4.4×10~4 L mol^(-1)cm^(-1) and 0.0053 μg cm^(-2), respectively. Different analytical parameters were tested in detail. Interfering ion(cations and anions) effects were tested. Methods for Th(IV) determination by second and third-derivative spectrophotometry were also introduced at about 344 and 341 nm, respectively. These two derivative orders offer the feature of sensitivity without the necessity for solvent extraction,heating, or pre-concentration steps. Finally, the methods were successfully utilized for Th(IV) determination in monazite, environmental water, and wastewater samples.

IMPROVEMENT OF FLUORIMETRIC AND UV－VISIBLE SPECTROPHOTOMETRIC ASSAY METHODS FOR MEASURING NITRIC OXIDE AND／OR EDRF IN BLOOD

The increasing importance of endothelium-derived relaxing factor(EDRF),which has now been identified as nitric oxide (NO),has been underscored by the eltlcidation of its role'in a growing number of normal and pathophysiological processes. Therefore techniques for detection of nitric oxide should serve as useful tools in defining the role of nitric oxide to these processes.We have improved a simple, sensitive assay methods for determination of nitric oxide in blood, tissue, and other body fluids both by fluorometric and by ultraviolet-visible spectrophotometric measurements. Data obtained by floores cence and by UV-visible assay were correlated well (r=0. 9938, P<0. 0001 ).Linearity:0.1￣ 100μmol/L,r =0.9996,P<0.0001. The minimum detection limit were < 10pmol/L. Within-and between-run CVs were 2. 48%and 4. 62% (n = 10),respectively.Reference values for healthy adults(n=40) were(9.82 ± 1. 57) pmol/L. In conclusion:the methods is sensitive, specific,and precise. It is fairly rapid and simple to perform andrequires no pretreatment of sample, i. e., plasma and urine.The value can be obtained by fluorimeter and/or UV-visible spectrophotometer.The present method is sufficiently rapid and simple to make this a practical choice for many laboratories.

石油产品中间馏分芳烃含量分析方法

对目前常见的石油产品中间馏分芳烃含量测定标准分析方法、荧光指示剂吸附法(FIA法)、气相色谱—质谱联用法(GC-MS)和高效液相色谱法(HPLC)做了分析与讨论。荧光指示剂法准确度与重复性均不高,只能得到<315℃馏分中芳烃总量,GC-MS和高效液相色谱法分析中间馏分芳烃,准确度,精密度都较高,给出的信息也多,但仪器价格昂贵,分析成本高。文中介绍了以紫外分光光度法分析石油产品中芳烃及芳烃衍生物的几种方法。紫外分光光度法分析石油各类产品,步骤简单,时间短,准确度较高,在排除干扰物质后,可以作为石油产品芳烃含量的日常监测手段。

Application of the Ion Pair of 2-(5-Bromo-2-pyridylazo)-5-diethylaminophenol and Ammonium Tetraphenylborate for Preconcentration of Trace Vanadium and Determination by Third Derivative Spectrophotometry

Vanadium is quantitatively retained on 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP)-ammonium tetraphenylborate with microcrystalline naphthalene or by a column method in the pH range of 2.1–4.5 from a large volume of aqueous solutions of various samples. After filtration, the solid mass consisting of the vanadium complex and naphthalene was dissolved with 5 mL of dimethylformamide and the metal was determined by the third derivative spectrophotometry. Vanadium complex can alternatively be quantitatively adsorbed on ammonium tetraphenylborate-naphthalene adsorbent packed in a column and determined similarly. About 0.05 μg of vanadium can be concentrated in a column from 250 mL of aqueous sample, where its concentration is as low as 0.2 ng/mL. The interference of a large number of anions and cations has been studied and the optimized conditions developed were utilized for the determination of trace amount of vanadium in various samples.

油气田用咪唑啉类缓蚀剂浓度的检测方法

有机胺咪唑啉及其衍生物以其优异的缓蚀性能被广泛地应用在实际生产中，此类缓蚀剂的浓度测定对于缓蚀剂的实际使用、工艺控制以及新型缓蚀剂的研究与应用具有重要的意义。在分析比较阳离子表面活性剂浓度测定方法的基础上，找到了一种较为简单快速的有机胺咪唑啉类缓蚀剂浓度的检测方法——显色剂分光光度法。结果表明：在中性介质中，咪唑啉与显色剂形成1：2的蓝色缔合物，最大吸收波长位于600nm处，表观摩尔吸光系数为2．97×10^3L·mol^-1·cm^-1,咪唑啉的浓度在0～100mg/L范围内遵循比耳定律。标准曲线线性回归方程为A=0．00484C，相关系数r=0．99913。利用这一方法来测定咪唑啉类缓蚀剂的浓度，受常见阴阳离子干扰较小，可应用于油气井中常用的咪唑啉类缓蚀剂的浓度测定。

一阶导数光谱法同时测定石英砂中铁和铝的研究

研究了在 pH =6 0的HAc NaAc缓冲体系中 ,Al(Ⅲ )和Fe(Ⅲ )分别与乙二醇二乙醚二氨基四乙酸(EGTA) ,邻苯三酚红 (PR) ,溴化十六烷基吡啶 (CPB)形成的四元络合物的性质 ,利用一阶导数光谱法对微量铁和铝进行了同时测定 ,测定的变异系数分别为 4 5 %和 1 1% ,加标回收率分别为 93～ 98%和 95～ 10 2 % 。

UV法测定异噻唑啉酮衍生物活性物含量

采用紫外分光光度法测定了异噻唑啉酮衍生物活性物含量及其氯比,结果表明:在273.0 nm波长下检测,线性范围为0～30.00 mg/L,方法检出限为0.012 mg/L,实际样品的加标回收率为98.9%～101.3%,RSD为0.50%～2.36%;氯比为2.6～3.4时,其半定量的最大吸收波长λmax为272.4～273.6 nm。该测定方法简便、快速、准确,可用于异噻唑啉酮衍生物活性物含量的测定和氯比的半定量测定。

三重-比导数分光光度法及其应用研究

提出了可以应用于三元混合物同时测定的三重 比导数分光光度法,阐述了三重 比导数分光光度法的基本原理,研究了三重 比导数分光光度法在三元复方制剂增效联磺片中磺胺甲口恶唑(SMZ)、磺胺嘧啶(SD)、甲氧苄啶(TMP)的同时测定。试验结果表明,增效联磺片中SMZ、SD、TMP的回收率分别为102 1%(RSD=2.7%,n=20)、100.5%(RSD=1.8%,n=20)、101.2%(RSD=4 3%,n=20)。

导数-三波长光度法同时测定肉制品中亚硝酸盐和硝酸盐的研究

本文提出了导数三波长光度法同时测定NO_2^-和NO_3^-显色化合物的新方法,并利用自编程序完成测定,操作简单快速。该法直接测定NO_2^-和NO_3^-与间苯二酚在浓H_2SO_4介质中生成的有色产物,它们均在0～14μg/10ml范围内服从比耳定律,其表观摩尔吸收系数△εNO_3^-为8.28×10~2L·mol^(-1)·cm^(-1)和△εNO_2^-为3.85×10~3L·mol^(-1)·cm^(-1)。应用该法对市售熟牛肉和午餐肉进行了分析,获得满意结果。