Simultaneous spectrophotometric determination of three food dyes by using the first derivative of ratio spectra

Ternary mixtures of colorants E-123 (Amaranth), E-124 (Ponceau 4R) and E-120 (Carminic acid) are resolved by using the first derivative ratio spectrum-zero crossing method without the need for any separation step. Calibration graphs were linear up to 64 mg l⁻¹ of carminic acid, 32 mg l⁻¹ of Amaranth and 32 mg l⁻¹ of Ponceau 4R. The method was applied to different commercial food products and results concordant with high performance liquid chromatography were obtained.     

Simultaneous spectrophotometric determination of metformin hydrochloride and glibenclamide in binary mixtures using combined discrete and continuous wavelet transforms

In this work, a combined discrete and continuous wavelet transform analysis was developed for simultaneous spectrophotometric determinations of metformin hydrochloride and glibenclamide, two antidiabetic drugs, in binary mixtures without any chemical pretreatment. Absorption spectra were subjected to the 4-level db4 discrete wavelet transform (DWT) for signal de-noising. Selected continuous wavelet transform (CWT) families (rbio3.1 with scaling factor, a = 80, and gaus2, a = 60) were applied on these de-noised signals. Finally, a zero-crossing technique was used for the construction of calibration curves for both drugs. The proposed method was validated by analyzing synthetic mixtures of the investigated drugs with various concentrations. The amount of metformin hydrochloride and glibenclamide were determined by using CWT amplitudes in zero-crossing points. The mean recovery values of metformin hydrochloride and glibenclamide were found between 98.6-102.0 and 97.9-102.4% for rbio3 and 98.3-101.2 and 97.1-101.4% for gaus2 families, respectively. The obtained results showed that the developed method is a simple, rapid and precise procedure for the simultaneous determination of metformin hydrochloride and glibenclamide in binary mixtures.     

偏最小二乘-分光光度法同时测定福美锌和代森锰农药残留量

利用紫外可见分光光度法研究了农药福美锌和代森锰与苯基荧光酮的相互作用,发现反应后的产物分别在波长为551和554 nm处最大有吸收,但光谱严重重叠.实验采集了450～700 nm波长范围吸光度数据,并对该数据进行一阶求导后用偏最小二乘法处理,据此建立了偏最小二乘-分光光度法同时测定福美锌和代森锰两种农药的新方法.福美锌和代森锰的线性范围分别为0.3～6.0和0.2～3.5 μg/mL;检出限分别为0.22和0.13 μg/mL.混合样品分析无需分离,方法简单、快速.用于水果、大米和自来水等实际样品测定.     

Simultaneous determination of beryllium and aluminium in mixtures using derivative spectrophotometry

The spectrophotometric determination of beryllium and aluminium with 5,8-dihydroxy-1,4-naphthoquinone in the presence of a non-ionic surfactant is reported. Absorption maxima, molar absorptivity and Sandell's Sensitivity of 1:2 (M:L) beryllium and aluminium complexes are, 585 nm and 598 nm, 1.63 x 10(4) l.mole(-1).cm(-1) and 2.04 x 10(4) l.mole(-1).cm(-1), and 0.55 ng/cm(2) and 1.32 ng/cm(2) respectively. Beer's law is obeyed between 7.20-3.96 x 10(2) ng/ml beryllium and 1.08 x 10(1)-1.08 x 10(3) ng/ml aluminium. A method for simultaneous determination of beryllium and aluminium in their mixture using derivative spectra is described. The range 3.6 x 10(1)-3.6 x 10(2) ng/ml beryllium could be determined in the presence of 1.08 x 10(2)-1.08 x 10(3) ng/ml aluminium, and vice versa.     

A ratio derivative spectrophotometric method for the simultaneous determination of uranium and plutonium

A ratio derivative spectrophotometric method has been developed for the simultaneous determination of uranium and plutonium at mg levels in 1M HNO₃ medium. In this method the overlapping spectra of uranium and plutonium are well resolved by making use of the first derivative of the ratios of their direct absorption spectra. The derivative ratio absorbances of uranium and plutonium are measured at 411.2 and 473.8 nm, respectively for their quantification. The method is simple, fast and does not require separation of uranium and plutonium. Another salient feature of the method is that it does not lead to generation of analytical waste thereby minimising the efforts required for the recovery of plutonium. Uranium in the conc. range of 10–25 mg/g and plutonium in the conc. range of 0.5 to 2 mg/g (U/Pu ratio varying from about 10 to 25) were determined in the same aliquot with a precision and accuracy of about 0.5% and 1%, respectively.     

Development and validation of spectrophotometric methods for determination of some cephalosporin group antibiotic drugs

A simple and direct spectrophotometric method is developed for the determination of some cephalosporin group antibiotic drugs such as Loracarbef (Lora), Ceftazidime (Ceft), and Cefaclor (Cefa) in bulk and pharmaceutical formulations. The optimum conditions for the analysis of aqueous solutions of drugs are studied. Under the optimum conditions, the three drugs could be assayed in the concentration range 2–9 × 10⁻⁵, 2–6 × 10⁻⁵, and 3–9 × 10⁻⁵ M for Lora, Ceft and Cefa, respectively. Detection and quantification limits are calculated. The obtained results showed good recoveries of 100.4, 107.4, and 100.7% for Lora, Ceft, and Cefa, respectively. The results obtained are compared favorably with those given by literature methods.     

主成分-偏最小二乘动力学分光光度法同时测定农药两组分

对氨基甲酸酯杀虫剂残杀威（PRO）和异丙威（ISO）的速差动力学光度法同时测定进行了研究。残杀威和异丙威均能在碱性条件下发生水解，水解生成的酚盐，均可以与对氨基苯酚及高碘酸钾混合物发生反应生成兰色化合物，且这是一个反应速率适中的动力学反应。本实验在538nm-700nm采集多个时间点下多个波长的动力学－－吸收光谱数据，构成量测矩阵。采用主成分－偏最小二乘法（PC－PLS）对测定数据进行了解析。本文对环境水样中残杀威和异丙威的含量进行了测定。取得了较好的分析结果。从而提出了一种易于实现，准确度高的残杀威和异丙威的同时测定新方法。     

First derivative of the ratio spectra method for resolving iodide and thiocyanate in binary mixtures

A new method is described to analyse the binary mixture of iodide (I(-)) and thiocyanate (SCN(-)) ions, using the first derivative of the ratio spectra obtained by mathematical treatment of the data. The method is based on the formation of mixed ligand complexes between benzohydroxamic acid (BHA), vanadium (V) and I(-) or SCN(-) and their extraction in ammonium quaternary salt dissolved in toluene. Calibration graphs for 2-9 mug/ml of I(-) and for 2-6 mug ml of SCN(-) were established by measuring the analytical signals at 376 nm for I(-) and at 400.6 nm for SCN(-). The method has been applied for determining both ions in waste water of an power station at ng/ml levels after a preconcentration step with C(18), without any separation step.     

Simultaneous determination of cinnarizine and nicergoline in a binary mixture using first derivative spectra,first derivative of ratio spectra and multivariate calibration techniques

Four methods are described for the simultaneous determination of cinnarizine (Cinn) and nicergoline (Nic). The first method is based on the first derivative (¹ D) ultraviolet spectrophotometry, with zero crossing and peak to base measurement. The first derivative amplitudes at 216.1 and 235.0 nm were selected for the assay of cinnarizine and nicergoline, respectively. The second method is based on the first derivative of the ratio-spectra (¹ DD) obtained by measurement of the amplitudes at 256 and 290.6 nm for cinnarizine and nicergoline, respectively. The other two chemometric methods applied were classical least squares (CLS) and inverse least squares (ILS). The calibration of these chemometric methods that involves absorbance and concentration data matrices is used for the prediction of unknown concentrations of Cinn and Nic. The numerical values were calculated by using Matlab R12 version 6.0 and Origin 5.0 software. The linear ranges are 1–40 and 1–46 μg/mL for cinnarizine and nicergoline, respectively, for all methods. The four methods were successfully applied to assaying the pharmaceutical formulations (Cinibral® tablets).     

Development and validation of TLC–densitometric method for simultaneous determination of two binary antihypertensive mixtures containing felodipine in fixed dose combinations

A new densitometric thin‐layer chromatographic method has been developed for simultaneous determination of two binary mixtures containing felodipine in combination with either metoprolol (mixture I) or ramipril (mixture II). The two mixtures were quantitatively separated on 60 F254 silica gel plates using toluene–ethyl acetate–methanol–ammonia as mobile phase with UV detection at 233 and 229 nm for mixtures I and II, respectively. The studied drugs were satisfactorily resolved with retention factor (R_f) values of 0.34 ± 0.03 and 0.65 ± 0.03 for metoprolol and felodipine, respectively, in mixture I and 0.35 ± 0.03 and 0.74 ± 0.03 for ramipril and felodipine, respectively, in mixture II. Linearity ranges were 2000–7000 and 200–700 ng/band for metoprolol and felodipine, respectively, in mixture I and 1500–4000 ng/band for both ramipril and felodipine in mixture II. Correlation coefficient (r) values were 0.9968 for both metoprolol and felodipine in mixture I and 0.9993 for ramipril and 0.9989 for felodipine in mixture II. The method has been validated according to International Conference on Harmonization guidelines and has been successfully applied for determination of the studied drugs in their dosage forms without interference from commonly encountered excipients. Copyright © 2015 John Wiley & Sons, Ltd.     

Simultaneous determination of copper and iron by second derivative spectrophotometry using mixtures of ligands

A highly sensitive and selective second derivative spectrophotometric method has been developed for the determination of copper and iron in mixtures. The method is based on the separation of the analytes by liquid-liquid extraction as picrate ion pairs. Iron-picrate, reacts in the organic phase of DCE with 5-phenyl-3-(4-phenyl-2-pyridinyl)-1,2,4-triazine (PPT). Similarly the copper-picrate reacts with 2,9-dimethyl-4,7-diphenyl-1,10-phenantroline (bathocuproine). The extracts were evaluated directly by derivative spectrophotometric measurement, using the zero-crossing approach for determination of copper and graphic method for iron. Iron and copper were thus determined in the ranges 8-120 ng ml(-1) and 8-125 ng ml(-1), respectively, in the presence of one another. The detection limits achieved (3sigma) were 2.9 ng ml(-1) of iron and 2.8 ng ml(-1) of copper. The relative standard deviations were in all instances less than 2.1%. The proposed method was applied to the determination of both analytes in river and tap water and the results were consistent with those provided by the AAS standard method.     

Determination of antihypertensive mixtures by use of a chemometrics-assisted spectrophotometric method

A simple multivariate calibration method for analysis of two types of hypotensive mixture is described. The mixtures are composed of chlorthalidone with atenolol or chlorthalidone with both amiloride hydrochloride and atenolol. The components of the mixtures result in substantial spectral overlap—between 87.5 and 91.0%. Resolution of the mixtures under investigation has been accomplished mainly by using CLS and PCR methods. The components in each mixture have been simultaneously determined in three commercial dosage forms with high accuracy and without interference from commonly encountered excipients and additives. Good recoveries were obtained with both synthetic mixtures and commercial tablets. The results obtained were compared with those from pharmacopeial methods and found to be in good agreement. The results obtained from CLS and PCR were also compared with those obtained from a ¹D spectrophotometric method.     

Isodifferential derivative approach to the spectrophotometric determination of nickel and cobalt mixtures

A graphical method for measuring derivative amplitudes in binary mixtures with overlapping spectra is described. The method is based on the interference-free character of the isodifferential points in the derivative calibration graphs. Cobalt and nickel mixtures are analyzed in the range 0.01–2.5 μg ml^?1 by the formation of coloured chelates with benzyl-2-pyridylketone 2-pyridylhydrazone, with relative standard deviations ?1.5%.     

Mean centering of ratio spectra as a new spectrophotometric method for the analysis of binary and ternary mixtures

In this paper a new and very simple method was developed for the simultaneous determination of binary and ternary mixtures, without prior separation steps. This method is based on the mean centering of ratio spectra. The mathematical explanation of the procedure is illustrated. After modeling procedure, the method has been successfully applied to the simultaneous analysis of binary mixtures of mefnamic acid and paracetamol and ternary mixtures of acetylsalysilic acid, ascorbic acid and paracetamol. The analytical characteristics of the method such as detection limit, accuracy, precision, relative standard deviation (R.S.D.) and relative standard error (R.S.E.) was calculated. The results showed that the proposed method is simple, rapid, accurate and precise method for analysis of binary and ternary mixtures.     

Determination of lamivudine and zidovudine in binary mixtures using first derivative spectrophotometric, first derivative of the ratio-spectra and high-performance liquid chromatography-UV methods

Three methods are presented for the simultaneous determination of lamivudine and zidovudine. The first method depends on first derivative UV spectrophotometry, with zero-crossing and peak-to-base measurement. The first derivative amplitudes at 265.6 and 271.6 nm were selected for the assay of lamivudine and zidovudine, respectively. The second method depends on first derivative of the ratio-spectra by measurements of the amplitudes at 239.5 and 245.3 nm for lamivudine and 225.1 and 251.5 nm for zidovudine. Calibration graphs were established for 1-50 μg/ml for lamivudine and 2-100 μg/ml for zidovudine. In the third method (HPLC), a reversed-phase column with a mobile phase of methanol:water:acetonitrile (70:20:10 (v/v/v)) at 0.9 ml/min flow rate was used to separate both compounds with a detection of 265.0 nm. Linearity was obtained in the concentration range of 0.025-50 μg/ml for lamivudine and 0.15-50 μg/ml for zidovudine. All of the proposed methods have been extensively validated. These methods allow a number of cost and time saving benefits. The described methods can be readily utilized for analysis of pharmaceutical formulations. There was no significant difference between the performance of all of the proposed methods regarding the mean values and standard deviations. The described HPLC method showed to be appropriate for simultaneous determination of lamivudine and zidovudine in human serum samples.     

Simultaneous derivative spectrophotometric determination of thorium and uranium in a micellar medium

Derivative photometric methods for trace analysis of Th(IV) and UO₂(II), and their simultaneous determination in mixtures using 5,8-dihydroxy-1,4-naphthoquinone in a micellar medium are reported. Molar absorptivity and Sandell's sensitivity of 1:2 Th(IV) and 1:1 UO₂(II) complexes at their λ_max, 614.5 nm and 637.0 nm are, 1.19 × 10⁴ 1/mol/cm and 1.12 × 10⁴ 1/mol/cm and 1.95 × 10⁻² μg/cm² and 2.13 × 10⁻² μg/cm² μg/cm², respectively. Calibration graph is linear over the range 9.28 × 10⁻²−18.56 μg/ml of Th(IV) and 9.52 × 10⁻²−19.04 μg/ml of UO₂(II). Though presence of Th(IV) and UO₂(II) causes interference in each others determination, 9.28 × 10⁻¹−9.28 μg/ml Th(IV) and 9.52 × 10⁻¹−9.52 μg/ml UO₂(II) when present together, can be simultaneously determined using derivative spectra.     

Simultaneous determination of tartrazine and sunset yellow by derivative spectrophotometry and ratio spectra derivative

Two methods for determining Tartrazine and Sunset Yellow in mixtures by first derivative spectrophotometry and by first derivative of the ratio spectra are described. The procedures do not require any separation step. By the first method, the measurements are obtained in the zero-crossing wavelengths and the calibration graphs are linear up to 20 microg/ml of Tartrazine and up to 40 microg/ml of Sunset Yellow. The determinations of Tartrazine and Sunset Yellow are also done by the first derivative of the ratio spectra. The methods are applied for determining both compounds in four commercial food products.     

Smart stability-indicating spectrophotometric methods for determination of binary mixtures without prior separation

Ratio subtraction and isosbestic point methods are 2 innovating spectrophotometric methods used to determine vincamine in the presence of its acid degradation product and a mixture of cinnarizine (CN) and nicergoline (NIC). Linear correlations were obtained in the concentration range from 8-40 microg/mL for vincamine (I), 6-22 microg/mL for CN (II), and 6-36 microg/mL for NIC (III), with mean accuracies 99.72 +/- 0.917% for I, 99.91 +/- 0.703% for II, and 99.58 +/- 0.847 and 99.83 +/- 1.039% for III. The ratio subtraction method was utilized for the analysis of laboratory-prepared mixtures containing different ratios of vincamine and its degradation product, and it was valid in the presence of up to 80% degradation product. CN and NIC in synthetic mixtures were analyzed by the 2 proposed methods with the total content of the mixture determined at their respective isosbestic points of 270.2 and 235.8 nm, and the content of CN was determined by the ratio subtraction method. The proposed method was validated and found to be suitable as a stability-indicating assay method for vincamine in pharmaceutical formulations. The standard addition technique was applied to validate the results and to ensure the specificity of the proposed methods.     

Kinetic determination of alcohols and their binary mixtures with a stopped-flow spectrophotometric technique

The kinetic method described for the determination of a single alcohol (? 5 X 10^-4 M), or of a binary mixture of alcohols in aqueous solution is based on fast oxidation by silver(II), monitored spectrophotometrically by using a stopped-flow technique. Mixtures of alcohols having rate constants differing by a factor of ?3 can be resolved. The lower limit of determination is ca. 5 × 10^-4 M.