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.

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.

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.

A Structure and Antioxidant Activity Study of Paracetamol and Salicylic Acid

The paracetamol has more antioxidant properties than the salicylic acid on the several oxidative stress-forced models and one possible mechanism is due to electron or hydrogen transfer by the evaluated hydroxyl radicals. The antioxidant mechanism for the compounds studied here was performed by molecular modeling using quantum chemical calculations at the B3LYP level of theory. Our results show that the paracetamol has more antioxidant properties than the salicylic acid in experimental and theoretical studies. The theoretical mechanism show that the hydrogen transfer is more favorable than the electron transfer. From the study it was concluded that the electron abstraction for paracetamol is more favored than salicylic acid.

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.

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.

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

A dual wavelength differential first derivative spectrophotometric method has been developed to standardize the concentration of a saturated aqueous solution of carbon monoxide (CO) as the standard and to identify and to determine CO formed during the microsomal metabolism of xenobiotics in vitro. The method can significantly eliminate the background interference in the assay media and increase the quantitative accuracy and the sensitivity. There is a good linear relationship between CO concentration in the range of 2～10 μmol·L 1 CO and the distance D between the first derivative peak at 415 nm amd valley at 426 nm with r=0.9999(n=5),the regression equation being C (mmol·L 1 )=17.6D 0.4, the detection limit lower than 0.1 μmol·L 1 CO. The average recoveries of CO from the assay system and the sample were 102.1%, RSD=2.9% (n=7) and 79.7%, RSD=6.8% (n=12),respectively. The RSD of within day was 4.4%(n=18),and the RSD of day to day was 6.1%(n=16). By this method, four trihaloanilines and one trihalobenzene were tested, the results showed that only 2,4,5 trifluoroaniline could be converted to CO by the incubation with rat hepatic microsomes, NADPH and oxygen, the ability of phenobarbital or dexamethasone to induce rat hepatic microsomes to catalyze CO formation was 3 or 8 times higher than that of the control.

Serum paraquat concentration detected by spectrophotometry in patients with paraquat poisoning

BACKGROUND：Paraquat （PQ） is a world-wide used herbicide and also a type of common poison for suicide and accidental poisoning. Numerous studies have proved that the concentration of serum PQ plays an important role in prognosis. Spectrophotometry, including common spectrophotometry and second-derivative spectrophotometry, is commonly used for PQ detection in primary hospitals. So far, lack of systematic research on the reliability of the method and the correlation between clinical features of patients with PQ poisoning and the test results has restricted the clinical use of spectrophotometry. This study aimed to evaluate the reliability and value of spectrophotometry in detecting the concentration of serum PQ. METHODS：The wavelengths for detecting the concentration of serum PQ by common and second-derivative spectrophotometry were determined. Second-derivative spectrophotometry was applied to detect the concentration of serum PQ. The linear range and precision for detection of PQ concentration by this method were confirmed. The concentration of serum PQ shown by second- derivative spectrophotometry and HPLC were compared in 8 patients with PQ poisoning. Altogether 21 patients with acute poisoning 4 hours after PQ ingestion treated in the period of October 2008 to September 2010 were retrospectively reviewed. The patients were divided into higher and lower than 1.8 μg/mL groups based on their concentrations of serum PQ measured by second-derivative spectrophotometry on admission. The severity of clinical manifestations between the two groups were analyzed with Student＇s t test or Fisher＇s exact test. RESULTS：The absorption peak of 257 nm could not be found when common spectrophotometry was used to detect the PQ concentration in serum. The calibration curve in the 0.4-8.0 μg/mL range for PQ concentration shown by second-derivative spectrophotometry obeyed Beer＇s law with r=0.996. The average recovery rates of PQ were within a range of 95.0% to 99.5%, relative standard deviation （RSD） was within 1.35% to 5.41% （n=6）, and the lower detection limit was 0.05 μg/mL. The PQ concentrations in serum of 8 patients with PQ poisoning shown by second-derivative spectrophotometry were consistent with the quantitative determinations by HPLC （r=0.995, P〈0.0001）. The survival rate was 22.2% in patients whose PQ concentration in serum was more than 1.8 μg/mL, and the incidences of acidosis, oliguria and pneumomediastinum in these patients were 55.6%, 55.6% and 77.8%, respectively. These clinical manifestations were different significantly from those of the patients whose PQ concentration in serum was less than 1.8 pg/mL （P〈0.05）. CONCLUSIONS： For common spectrophotometry, the wavelength at 257 nm was not suitable for detecting serum PQ as no absorbance was shown. Second-derivative spectrophotometry was reliable for detecting serum paraquat concentration. Serum PQ concentration detected by second- derivative spectrophotometry could be used to predict the severity of clinical manifestations of patients with PQ poisoning, and PQ content higher than 1.8 tJg/mL 4 hours after ingestion could be an important predictive factor for poor prognosis.

Terahertz spectrum clustering of traditional Chinese medicine based on first derivative characteristics

In order to deal with the unclear absorption peak caused by the absorption peak overlap of traditional Chinese medicine(TCM)and other mixtures,a method of three unsupervised clustering algorithms as K-means,K-medoids and Fuzzy C-means(FCM)combined with the first derivative characteristics of terahertz absorption spectrum,is proposed to perform the terahertz spectra clustering of Sanchi and other three kinds of TCM compared with their easily-confused products(ECPs).These three unsupervised clustering methods complement the scope of the supervised learning classification method.The first derivative of the spectrum could amplify the difference in the absorption coefficient with different substances,so that the obvious absorption peak can be revealed.Experiments shows that these three clustering algorithms can achieve good results by combining the origin absorption coefficient with its first-order derivative as the characteristic data,and among which K-means does the best with the accuracy of95.32%.Compared with pure absorption coefficient data clustering,the accuracy in this study has been significantly improved,especially for the non-absorption-peak TCM classification.And the accuracy of K-means algorithm is improved by5.38%.Besides,clustering algorithms in this study have strong anti-interference ability to the error data.

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.

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.

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.

动物性食品中盐酸多西环素残留量荧光检测方法研究

利用表面活性剂可以提高物质荧光强度这一原理以及固相萃取技术,建立荧光法检测动物性食品中盐酸多西环素残留量。讨论表面活性剂类型和加入量,反应温度、处理时间、加入顺序等条件对盐酸多西环素荧光强度的影响。设计了三因素三水平正交实验,优化样品前处理过程。选择Mcllvaine-Na2EDTA缓冲液作为提取剂,甲醇、乙酸乙酯(1∶9)混合液作为洗脱剂,涡旋萃取时间为2 min。在1 cm石英比色皿中,设定激发波长(λex)为378 nm,发射波长(λem)为438 nm,冰浴30 min后扫描测定。在7.14×10^(-4)~5.71×10^(-2)mg/mL时,盐酸多西环素的浓度和荧光强度线性关系较好(r=0.9995),检出限为74.99 ng/mL,加标回收率为79.93%~90.48%,相对标准偏差为0.34%~0.73%。该方法可用于定性定量检测动物性食品中盐酸多西环素残留量。

新铜试剂分光光度法测定片剂中的对乙酰氨基酚含量及其反应机理的研究

使用分光光度法测定扑热息痛中主要化学成分对乙酰氨基酚的含量。结果表明：在0.04~8.00 mg·L-1范围内对乙酰氨基酚含量与吸光度（A）呈良好的线性关系,其线性方程：A=0.1210c＋0.0261,相关系数r=0.9968。表观摩尔吸光系数为1.8×10^4 L·mol-1·cm-1,平均回收率为100.2%,相对标准偏差RSD为1.51%。该实验所用仪器简单,且操作方便、快速。用该方法测定扑热息痛片剂对乙酰氨基酚的含量,取得了较好的效果。

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。

双波长紫外分光光度法同时测定小儿退烧片中对乙酰氨基酚和乙酰水杨酸的含量(英文)

建立用双波长等吸收度法同时测定对乙酰氨基酚和乙酰水杨酸含量的方法.应用双波长分光光度法,选择对乙酰氨基酚的等吸收点波长232.5nm,252.0nm为乙酰水杨酸的测定波长;同样,选择乙酰水杨酸的等吸收点波长243.5nm,283.5nm为对乙酰氨基酚的测定波长.乙酰水杨酸的回归方程为A=0.03218C+0.00277,r=0.9999;对乙酰氨基酚的回归方程为A=0.05396C+0.00561,r=0.9999.样品中乙酰水杨酸和对乙酰氨基酚相当于标示量的百分含量分别为99.10%和102.37%(n=3).乙酰水杨酸的平均回收率是99.52%,对乙酰氨基酚的平均回收率是99.71%.本法快速、简便,定量准确,用于小儿退烧片中乙酰水杨酸和对乙酰氨基酚含量的同时测定可获得满意的结果.

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 % 。