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1

Sensitive Spectrophotometric Methods for Determination of Non UV Absorbing Ethambutol  

Microsoft Academic Search

Two simple and sensitive spectrophotometric methods are described for the quantitative determination of ethambutol. The first method is based on the reaction between dichlorophenol indophenol (DCPIP) and ethambutol to give bluish violet radical ions exhibiting maximum absorption at 640 nm. The second method depends upon the formation of yellow colored ethambutol picrate measurable at 430 nm. Obedience of both chromogens

Mohamed El-Sayed Mahrous

1992-01-01

2

Validation of HPLC and UV spectrophotometric methods for the determination of meropenem in pharmaceutical dosage form  

Microsoft Academic Search

A high-performance liquid chromatographic method and a UV spectrophotometric method for the quantitative determination of meropenem, a highly active carbapenem antibiotic, in powder for injection were developed in present work. The parameters linearity, precision, accuracy, specificity, robustness, limit of detection and limit of quantitation were studied according to International Conference on Harmonization guidelines. Chromatography was carried out by reversed-phase technique

Andreas S. L Mendez; Martin Steppe; Elfrides E. S Schapoval

2003-01-01

3

RP-HPLC and UV Spectrophotometric Methods for Estimation of Pirfenidone in Pharmaceutical Formulations.  

PubMed

High-performance liquid chromatographic and UV spectrophotometric methods were developed and validated for the quantitative determination of pirfenidone, a novel antifibrotic agent used in idiopathic pulmonary fibrosis. Chromatography was carried out by isocratic technique on a reversed-phase C18 Zorbax Eclipse plus column with mobile phase consisting of acetonitrile:water (35:65 %v/v) at flow rate of 0.7 ml/min. The UV spectrophotometric determinations were performed at 317 nm using methanol as a solvent. The proposed methods were validated according to International Conference on Harmonization ICH Q2 (R1) guidelines. The linearity range for pirfenidone was 0.2-5.0 and 3-25 ?g/ml for HPLC and UV method, respectively. Both the methods were accurate and precise with recoveries in the range of 98 and 102 % and relative standard deviation <2 %. The developed methods were successfully applied for determination of pirfenidone in tablets. PMID:25035534

Parmar, V K; Desai, S B; Vaja, T

2014-05-01

4

RP-HPLC and UV Spectrophotometric Methods for Estimation of Pirfenidone in Pharmaceutical Formulations  

PubMed Central

High-performance liquid chromatographic and UV spectrophotometric methods were developed and validated for the quantitative determination of pirfenidone, a novel antifibrotic agent used in idiopathic pulmonary fibrosis. Chromatography was carried out by isocratic technique on a reversed-phase C18 Zorbax Eclipse plus column with mobile phase consisting of acetonitrile:water (35:65 %v/v) at flow rate of 0.7 ml/min. The UV spectrophotometric determinations were performed at 317 nm using methanol as a solvent. The proposed methods were validated according to International Conference on Harmonization ICH Q2 (R1) guidelines. The linearity range for pirfenidone was 0.2-5.0 and 3-25 ?g/ml for HPLC and UV method, respectively. Both the methods were accurate and precise with recoveries in the range of 98 and 102 % and relative standard deviation <2 %. The developed methods were successfully applied for determination of pirfenidone in tablets. PMID:25035534

Parmar, V. K.; Desai, S. B.; Vaja, T.

2014-01-01

5

Solidphase UV spectrophotometric method for determination of ciprofloxacin  

Microsoft Academic Search

A simple and inexpensive method for the determination of ciprofloxacin has been developed using solid-phase spectrophotometry. The intrinsic absorbance of ciprofloxacin fixed on a dextran-type cation-exchange resin, Sephadex SP C-25, was measured directly at 277 and 380 nm after packing the gel beads in a 1-mm cell. Using a sample volume of 10 ml, the calibration graph was linear over

M Pascual-Reguera; Gertrudis Pérez Parras; Antonio Molina D??az

2004-01-01

6

Development of validated UV spectrophotometric method for in vitro analysis of sumatriptan in pharmaceutical preparations in comparison with HPLC  

Microsoft Academic Search

An accurate, simple reproducible and sensitive method for the determination of sumatriptan succinate was developed and validated.\\u000a According to this, sumatriptan succinate was determined using a UV spectrophotometric (UVS) technique and the results were\\u000a compared with the data of isocratic HPLC procedure on a Bondapack reversed-phase ODS or C18 Waters column (chemically bonded\\u000a to Spherisorb(particles (5 ?m), 4.6 mm ×

M. R. Pourmand; M. S. Azar; M. Aghavalijamaat

2011-01-01

7

Validated UV-spectrophotometric method for the evaluation of the efficacy of makeup remover.  

PubMed

A UV-spectrophotometric method for the analysis of makeup remover was developed and validated according to ICH guidelines. Three makeup removers for which the main ingredients consisted of vegetable oil (A), mineral oil and silicone (B) and mineral oil and water (C) were sampled in this study. Ethanol was the optimal solvent because it did not interfere with the maximum absorbance of the liquid foundation at 250 nm. The linearity was determined over a range of makeup concentrations from 0.540 to 1.412?mg?mL?¹ (R² = 0.9977). The accuracy of this method was determined by analysing low, intermediate and high concentrations of the liquid foundation and gave 78.59-91.57% recoveries with a relative standard deviation of <2% (0.56-1.45%). This result demonstrates the validity and reliability of this method. The reproducibilities were 97.32?±?1.79, 88.34?±?2.69 and 95.63?±?2.94 for preparations A, B and C respectively, which are within the acceptable limits set forth by the ASEAN analytical validation guidelines, which ensure the precision of the method under the same operating conditions over a short time interval and the inter-assay precision within the laboratory. The proposed method is therefore a simple, rapid, accurate, precise and inexpensive technique for the routine analysis of makeup remover efficacy. PMID:22243432

Charoennit, P; Lourith, N

2012-04-01

8

Validation of uv derivative spectrophotometric method for determination of benazepril hydrochloride in tablets and evaluation of its stability.  

PubMed

The absorbance and first-, second- and third-order derivative UV spectroscopic methods were applied for the determination of benazepril hydrochloride (BEN) in model solutions and tablets, as well as the estimation of its stability in solid phase. Derivative UV spectroscopy and HPLC methods were tested for: precision, linearity, accuracy and repeatability. HPLC was used as a reference method. The study presents that derivative UV spectroscopy (the first and second derivative only) and HPLC can be successfully applied for the quantitative analysis of benazepril hydrochloride both pure and in pharmaceutical formulations. Although, the first and second derivative spectrophotometric methods are fast, precise and accurate, but they cannot be used for evaluation of purity and stability of BEN in pharmaceutical formulations (due to a lack of selectivity). PMID:19702164

Stanisz, Beata; Paszun, Sylwia; Le?niak, Marcin

2009-01-01

9

New, simple and validated UV-spectrophotometric methods for the estimation of gatifloxacin in bulk and formulations  

Microsoft Academic Search

New, simple and cost effective UV-spectrophotometric methods were developed for the estimation of gatifloxacin in bulk and pharmaceutical formulations. Gatifloxacin was estimated at 286 nm in 100 mM phosphate buffer (pH 7.4) and 292 nm in 100 mM hydrochloric acid (pH 1.2). Linearity range was found to be 1–18 ?g ml–1 (regression equation: absorbance=0.0684×Concentration in ?g ml–1+0.0050; r2=0.9998) in the phosphate buffer (pH 7.4) and 1–14 ?g ml–1 (regression

K. Venugopal; Ranendra N. Saha

2005-01-01

10

Validation of UV spectrophotometric methods for the determination of dothiepin hydrochloride in pharmaceutical dosage form and stress degradation studies  

NASA Astrophysics Data System (ADS)

Spectrophotometric methods have been developed for the determination of dothiepin hydrochloride (DOTH) in both pure and tablet dosage form and their limits of detection and quantification have been evaluated. The methods are based on the measurement of the absorbance of a DOTH solution either in 0.1 N HCl at 229 nm (method A) or in methanol at 231 nm (method B). Beer's law is obeyed over a concentration range of 1-16 ?g/ml DOTH for both methods. Molar absorptivity values are calculated to be 2.48 × 104 and 2.42 × 104 l/(mol × cm) with Sandell sensitivity values of 0.0134 and 0.0137 ?g/cm2 for methods A and B, respectively. The degradation behavior of DOTH was investigated under different stress conditions such as acid hydrolysis, alkaline hydrolysis, water hydrolysis, oxidation, dry heat treatment, and UV-degradation. The drug undergoes significant degradation under oxidative conditions only.

Abdulrahman, Sameer A. M.; Basavaiah, K.; Cijo, M. X.; Vinay, K. B.

2012-11-01

11

Development and validation of a UV-spectrophotometric method for the determination of pheniramine maleate and its stability studies  

NASA Astrophysics Data System (ADS)

A sensitive, precise, and cost-effective UV-spectrophotometric method is described for the determination of pheniramine maleate (PAM) in bulk drug and tablets. The method is based on the measurement of absorbance of a PAM solution in 0.1 N HCl at 264 nm. As per the International Conference on Harmonization (ICH) guidelines, the method was validated for linearity, accuracy, precision, limits of detection (LOD) and quantification (LOQ), and robustness and ruggedness. A linear relationship between absorbance and concentration of PAM in the range of 2-40 ?g/ml with a correlation coefficient (r) of 0.9998 was obtained. The LOD and LOQ values were found to be 0.18 and 0.39 ?g/ml PAM, respectively. The precision of the method was satisfactory: the value of relative standard deviation (RSD) did not exceed 3.47%. The proposed method was applied successfully to the determination of PAM in tablets with good accuracy and precision. Percentages of the label claims ranged from 101.8 to 102.01% with the standard deviation (SD) from 0.64 to 0.72%. The accuracy of the method was further ascertained by recovery studies via a standard addition procedure. In addition, the forced degradation of PAM was conducted in accordance with the ICH guidelines. Acidic and basic hydrolysis, thermal stress, peroxide, and photolytic degradation were used to assess the stability-indicating power of the method. A substantial degradation was observed during oxidative and alkaline degradations. No degradation was observed under other stress conditions.

Raghu, M. S.; Basavaiah, K.; Ramesh, P. J.; Abdulrahman, Sameer A. M.; Vinay, K. B.

2012-03-01

12

Development and validation of reversed-phase column high-performance liquid chromatographic and first-derivative UV spectrophotometric methods for estimation of voriconazole in oral suspension powder.  

PubMed

This research paper describes validated reversed-phase high-performance column liquid chromatographic (RP-HPLC) and first-derivative UV spectrophotometric methods for the estimation of voriconazole (VOR) in oral suspension powder. The RP-HPLC separation was achieved on Phenomenex C18 column (250 x 4.6 mm id, 5 microm particle size) using water-acetonitrile (40 + 60, v/v; pH adjusted to 4.5 +/- 0.02 with acetic acid) as the mobile phase at a flow rate of 1.4 mL/min and ambient temperature. Quantification was achieved with photodiode array detection at 255 nm over the concentration range of 0.1-1 microg/mL with mean recovery of 99.49 +/- 0.83% for VOR by the RP-HPLC method. Quantification was achieved with UV detection at 266 nm over the concentration range of 8-20 microg/mL with mean recovery of 99.74 +/- 0.664% for VOR by the first-derivative UV spectrophotometric method. These methods are simple, precise, and sensitive, and they are applicable for the determination of VOR in oral suspension powder. PMID:18980120

Prajapati, Arun M; Patel, Satish A; Patel, Natvarlal J; Patel, Dipti B; Patel, Sejal K

2008-01-01

13

Development and Validation of a HPLC and an UV Spectrophotometric Methods for Determination of Dexibuprofen in Pharmaceutical Preparations.  

PubMed

A high-performance liquid chromatographic (HPLC) and a ultraviolet (UV) methods were developed and validated for the quantitative determination of Dexibuprofen (DI) in pharmaceutical dosage form. HPLC was carried out by reversed phase technique on a RP-18 column with a mobile phase composed of acetonitrile and 0.5% triethylamine (pH 7.5 adjusted with orthophosphoric acid (30?:?70, v/v)). UV method was performed with the ? max at 222.0?nm. Both the methods showed good linearity, reproducibility and precision. No spectral or chromatographic interferences from the tablet excipients were found in UV and HPLC. The method was successfully applied to commercial DEXIFEN tablets. Validation parameters such as linearity, precision, accuracy, and specificity were determined. The proposed method could be applicable for routine analysis of DI and monitoring of the quality of marketed drugs. PMID:22389866

Muralidharan, Selvadurai; Meyyanathan, Subramania Nainar

2011-01-01

14

Development and Validation of a HPLC and an UV Spectrophotometric Methods for Determination of Dexibuprofen in Pharmaceutical Preparations  

PubMed Central

A high-performance liquid chromatographic (HPLC) and a ultraviolet (UV) methods were developed and validated for the quantitative determination of Dexibuprofen (DI) in pharmaceutical dosage form. HPLC was carried out by reversed phase technique on a RP-18 column with a mobile phase composed of acetonitrile and 0.5% triethylamine (pH 7.5 adjusted with orthophosphoric acid (30?:?70, v/v)). UV method was performed with the ? max at 222.0?nm. Both the methods showed good linearity, reproducibility and precision. No spectral or chromatographic interferences from the tablet excipients were found in UV and HPLC. The method was successfully applied to commercial DEXIFEN tablets. Validation parameters such as linearity, precision, accuracy, and specificity were determined. The proposed method could be applicable for routine analysis of DI and monitoring of the quality of marketed drugs. PMID:22389866

Muralidharan, Selvadurai; Meyyanathan, Subramania Nainar

2011-01-01

15

Simultaneous estimation of ramipril, acetylsalicylic acid and atorvastatin calcium by chemometrics assisted UV-spectrophotometric method in capsules.  

PubMed

In the present work, three different spectrophotometric methods for simultaneous estimation of ramipril, aspirin and atorvastatin calcium in raw materials and in formulations are described. Overlapped data was quantitatively resolved by using chemometric methods, viz. inverse least squares (ILS), principal component regression (PCR) and partial least squares (PLS). Calibrations were constructed using the absorption data matrix corresponding to the concentration data matrix. The linearity range was found to be 1-5, 10-50 and 2-10 ?g mL-1 for ramipril, aspirin and atorvastatin calcium, respectively. The absorbance matrix was obtained by measuring the zero-order absorbance in the wavelength range between 210 and 320 nm. A training set design of the concentration data corresponding to the ramipril, aspirin and atorvastatin calcium mixtures was organized statistically to maximize the information content from the spectra and to minimize the error of multivariate calibrations. By applying the respective algorithms for PLS 1, PCR and ILS to the measured spectra of the calibration set, a suitable model was obtained. This model was selected on the basis of RMSECV and RMSEP values. The same was applied to the prediction set and capsule formulation. Mean recoveries of the commercial formulation set together with the figures of merit (calibration sensitivity, selectivity, limit of detection, limit of quantification and analytical sensitivity) were estimated. Validity of the proposed approaches was successfully assessed for analyses of drugs in the various prepared physical mixtures and formulations. PMID:21945907

Sankar, A S Kamatchi; Vetrichelvan, Thangarasu; Venkappaya, Devashya

2011-09-01

16

A comparative study of molecular complexation of [60]- and [70]fullerenes with 1,3,5-tribromobenzene by UV-vis spectrophotometric method.  

PubMed

By UV-vis spectrophotometric method it has been shown that 1,3,5-tribromobenzene (TBB) forms molecular complexes of 1:2 stoichiometry with [60]- and [70]fullerenes. An isosbestic point could be detected in case of the [70]fullerene complex. The formation constant of the [60]fullerene complex is higher than that of the [70]fullerene complex at each of the four temperatures under study. This is in opposite order of the electron affinities of the two fullerenes; moreover, no charge transfer band was observed in the spectra of either complex in solution. This indicates that van der Waals forces, rather than CT interactions, are responsible for complexation. The results reveal that the C-atoms at the pentagon vertices of [60]fullerene have greater polarizing power than those in [70]fullerene. PMID:16257694

Datta, Kakali; Mukherjee, Asok K

2005-11-01

17

A comparative study of molecular complexation of [60]- and [70]fullerenes with 1,3,5-tribromobenzene by UV-vis spectrophotometric method  

NASA Astrophysics Data System (ADS)

By UV-vis spectrophotometric method it has been shown that 1,3,5-tribromobenzene (TBB) forms molecular complexes of 1:2 stoichiometry with [60]- and [70]fullerenes. An isosbestic point could be detected in case of the [70]fullerene complex. The formation constant of the [60]fullerene complex is higher than that of the [70]fullerene complex at each of the four temperatures under study. This is in opposite order of the electron affinities of the two fullerenes; moreover, no charge transfer band was observed in the spectra of either complex in solution. This indicates that van der Waals forces, rather than CT interactions, are responsible for complexation. The results reveal that the C-atoms at the pentagon vertices of [60]fullerene have greater polarizing power than those in [70]fullerene.

Datta, Kakali; Mukherjee, Asok K.

2005-11-01

18

Development and Validation of a Novel Dual Wavelength UV-Spectrophotometric Method for the Simultaneous Estimation of Mycophenolate Mofetil and Prednisolone  

NASA Astrophysics Data System (ADS)

A dual wavelength UV-spectrophotometric method has been developed for the simultaneous estimation of mycophenolate mofetil and prednisolone. In this method two wavelengths were selected for the estimation of each drug in such a way that the difference in the absorbance was zero for the second drug on the respective wavelength for the first drug. This method was selected because of the overlapping of the absorbance maxima of the drugs. Prednisolone has equal absorbance value at wavelengths 235.11 and 261.33 nm; therefore, these two wavelengths were used to determine the concentration of mycophenolate mofetil in the combination. Similarly, 270.3 and 277.4 nm wavelengths were selected to determine the concentrations of prednisolone, where mycophenolate mofetil was observed with equal absorbance values. Regression analysis for the method shows good correlation in the concentration ranges 10-50 ?g/ml for mycophenolate mofetil and 2-10 ?g/ml for prednisolone. The method was validated using parameters provided as per ICH guidelines.

Kaur, J.; Sharma, P. Kumar; Namdev, K. Kumar; Bala, I.; Verma, S.

2014-07-01

19

Development and validation of an UV derivative spectrophotometric determination of Losartan potassium in tablets  

Microsoft Academic Search

Development and validation of an analytical UV derivative spectrophotometric method to quantify Losartan potassium used as a single active principle in pharmaceutical forms were done. Pharmacopeias have not yet provided an official method for its quantification. A study was carried out of all the parameters established by USP XXIV to validate an analytical method for a solid pharmaceutical form, i.e.

Olga C Lastra; Igor G Lemus; Hugo J Sánchez; Renato F Pérez

2003-01-01

20

A rapid and selective solid-phase UV spectrophotometric method for determination of ascorbic acid in pharmaceutical preparations and urine  

Microsoft Academic Search

Ascorbic acid was determined by a solid-phase UV spectrophotometry technique through the sorption of this on a dextran-type anion-exchange resin, Sephadex QAE A-25 and posterior direct measurement of its absorbance on the resin at 267 and 400 nm, packed in a 1-mm cell. The calibration graph was linear over the range 0.3–5.0 ?g ml?1. The sensitivity obtained is more than

A. Ruiz Medina; M. L Fernández de Córdova; A Molina D??az

1999-01-01

21

Simultaneous determination of atorvastatin calcium and olmesartan medoxomil in a pharmaceutical formulation by reversed phase high-performance liquid chromatography, high-performance thin-layer chromatography, and UV spectrophotometric methods.  

PubMed

Validated RP-HPLC, HPTLC, and UV spectrophotometric methods have been developed for the simultaneous determination of atorvastatin calcium (ATV) and olmesartan medoxomil (OLM) in a pharmaceutical formulation. The RP-HPLC separation was achieved on a Kromasil C18 column (250 x 4.6 mm, 5 microm particle size) using 0.01 M potassium dihydrogen o-phosphate (pH 4 adjusted with o-phosphoric acid)-acetonitrile (50 + 50, v/v) as the mobile phase at a flow rate of 1.5 mL/min. Quantification was achieved by UV detection at 276 nm. The HPTLC separation was achieved on precoated silica gel 60F254 plates using chloroform-methanol-acetonitrile (4 + 2+ 4, v/v/v) mobile phase. Quantification was achieved with UV detection at 276 nm. The UV-Vis spectrophotometric method was based on the simultaneous equation method that involves measurement of absorbance at two wavelengths, i.e., 255 nm (lambda max of OLM) and 246.2 nm (lambda max of ATV) in methanol. All three methods were validated as per International Conference on Harmonization guidelines. The proposed methods were simple, precise, accurate, and applicable for the simultaneous determination of ATV and OLM in a marketed formulation. The results obtained by applying the proposed methods were statistically analyzed and were found satisfactory. PMID:25051627

Soni, Hiral; Kothari, Charmy; Khatri, Deepak; Mehta, Priti

2014-01-01

22

UV-visible spectrophotometric simultaneous estimation of paracetamol and nabumetone by AUC method in combined tablet dosage form  

PubMed Central

Introduction: The present study deals with development and validation of a simple, rapid, sensitive and economic area under curve method for simultaneous estimation of paracetamol and nabumetone in bulk and tablet dosage form. Materials and Method: Area under curve method includes determination of area of paracetamol and nabumetone at absorption maxima, which for paracetamol was 248.8 ± 10 nm and for nabumetone was 269.2 ± 10 nm. Beer's law was obeyed in the concentration range of 5–25 ?g/mL for both paracetamol and nabumetone. Correlation coefficient was found to be 0.9983 and 0.9993 for paracetamol and nabumetone, respectively for area under curve method. Results: The analysis were validated statistically and by performing recovery studies. The mean percent recoveries were found satisfactory for the proposed method. The percentage recovery was found to be 101.67–102.43% for paracetamol and 96.69–98.49% for nabumetone. Conclusion: The proposed AUC method used for the simultaneous estimation of PARA and NAB in bulk and tablet dosage formrespectively. PMID:23781476

Rote, Ambadas R.; Kumbhoje, Prasanna A.; Bhambar, Rajendra S.

2012-01-01

23

Comparison of classic and derivative UV spectrophotometric methods for quantification of meloxicam and mefenamic acid in pharmaceutical preparations.  

PubMed

The methods for quantitative determination of meloxicam and mefenamic acid in pharmaceuticals by classic spectrophotometry - zero order derivative, first and second order derivatives spectrophotometry is described, using "peak - peak" (P-P) and "peak - zero" (P-O) measurements. The calibration curves are linear within the concentration range of 4.0 - 14.0 microg/mL for meloxicam and 14.0 - 24.0 microg/mL for mefenamic acid. The procedure is simple, rapid and the results are reliable. PMID:21648185

Pomykalski, Arkadiusz; Hopka?a, Hanna

2011-01-01

24

Development and validation of a HPLC and a UV derivative spectrophotometric methods for determination of hydroquinone in gel and cream preparations.  

PubMed

A high performance liquid chromatographic (HPLC) and a ultraviolet derivative spectrophotometric (UVDS) methods were developed and validated for the quantitative determination of hydroquinone (HQ) in gels and creams containing this compound as a unique active principle. Validation parameters such as linearity, precision, accuracy, specificity, limit of detection (LOD) and limit of quantitation (LOQ) were determined. HPLC was carried out by reversed phase technique on a RP-18 column with a mobile phase composed of methanol and water (20:80, v/v). The linearity in the range of 6.0-30.0 microg/mL present a correlation coefficient (r) of 0.9999, calculated by least square method. The LOD and LOQ were 0.08 and 0.26 microg/mL, respectively. Based on the preliminary spectrophotometric profile of HQ, a signal at 302.0 nm of the first derivative spectrum (1D302.0) was found adequate for validation. The linearity between signal 1D302.0 and concentration of HQ in the range of 10.0-26.0 microg/mL in sulfuric acid (0.1N) present a correlation coefficient (r) of 0.9999. The LOD and LOQ were 0.14 and 0.46 microg/mL, respectively. Statistical analysis by t- and F-tests, showed no significant difference at 95% confidence level between the two proposed methods. PMID:15936163

López García, P; Rocha Miritello Santoro, M I; Kedor-Hackmann, E R M; Kedor-Hackman, E R M; Kumar Singh, A

2005-09-15

25

UV derivative spectrophotometric and RP-HPLC methods for determination of imidapril hydrochloride in tablets and for its stability assessment in solid state.  

PubMed

Two methods for determination of imidapril hydrochloride (IMD) in the form of tablets were developed and the stability-indicative determination of IMD in solid state formulations by means of the proposed methods was investigated. IMD is not a pharmacopeial raw material, therefore there is no official method for its determination and purity assessment. The following analytical techniques were adopted for IMD determination: reverse-phase high performance liquid chromatography (RP-HPLC) and first derivative (1D) ultraviolet spectrophotometry. RP-HPLC analysis was performed with the use of LiChrosfer RP-18 column as a stationary phase and acetonitrile-methanol-phosphate buffer pH 2.0 (60:10:30 v/v/v) as a mobile phase. The proposed method showed good linearity (in a range 40.0 - 400.0 microg/mL), accuracy, precision and selectivity for: IMD, its degradation product, and for oxymetazoline as an internal standard (IS). Additionally, different spectrophotometric methods were tested, and the first derivative spectrophotometry was accepted for further research. This method showed good linearity (in a range 4.0 - 40.0 microg/mL), precision and accuracy. The proposed methods were successfully applied to the pharmaceutical dosage form containing the investigated compound without any interference from the excipients. Finally, the results of the suggested methods were statistically compared using t-Student and F-Snedecor tests in the assessment for their equivalence. PMID:21928708

Stanisz, Beata; Regulska, Katarzyna; Kolasa, Kinga

2011-01-01

26

Fia-spectrophotometric determination of thiamine after UV-irradiation.  

PubMed

The determination of thiamine was carried out by UV-photodegradation in a single-line flow-injection assembly. The UV-photodegradation of thiamine was carried out in the coil of the injection valve, constituted of a PTFE tubing, half of its length being helically coiled around a UV lamp. A peak with two adjoining maxima was produced by injection, corresponding to the absorbance of the irradiated and non-irradiated sample. The analytical parameter is the difference between the two peaks, measured at 264 nm. The calibration graph is linear over the 1.2-30 mug/ml range of thiamine hydrochloride in 0.1M HCl. The influence of certain admixed substances was studied and the method was tested for the determination of thiamine in tablets. PMID:18966184

Dane?, A F; Calatayud, J M

1994-12-01

27

Development and validation of an UV derivative spectrophotometric determination of Losartan potassium in tablets.  

PubMed

Development and validation of an analytical UV derivative spectrophotometric method to quantify Losartan potassium used as a single active principle in pharmaceutical forms were done. Pharmacopeias have not yet provided an official method for its quantification. A study was carried out of all the parameters established by USP XXIV to validate an analytical method for a solid pharmaceutical form, i.e. linearity, range, accuracy, precision and specificity. All these parameters were found in accordance with the acceptance criteria of Comité de Guías Oficiales de Validación de la Dirección General de Control de Insumos para la Salud de México. Based on the spectrophotometric characteristics of Losartan potassium, a signal at 234 nm of the first derivative spectrum (1D234) was found adequate for quantification. The linearity between signal 1D234 and concentration of Losartan potassium in the range of 4.00-6.00 mg l(-1) in aqueous solutions presents a square correlation coefficient (r2) of 0.9938. The mean recovery percentage was 100.7+/-1.1% and the precision expressed as relative standard deviation (R.S.D.) 0.88%. In addition, the proposed method is simple, easy to apply, low-cost, does not use polluting reagents and requires relatively inexpensive instruments. Then, it is a good alternative to existing methods for determining Losartan potassium in tablets provided that the pharmaceutical dosage form does not contain hydrochlorothiazide as second drug. PMID:12972082

Lastra, Olga C; Lemus, Igor G; Sánchez, Hugo J; Pérez, Renato F

2003-09-19

28

UV Spectrophotometric Simultaneous Determination of Paracetamol and Ibuprofen in Combined Tablets by Derivative and Wavelet Transforms  

PubMed Central

The application of first-order derivative and wavelet transforms to UV spectra and ratio spectra was proposed for the simultaneous determination of ibuprofen and paracetamol in their combined tablets. A new hybrid approach on the combined use of first-order derivative and wavelet transforms to spectra was also discussed. In this application, DWT (sym6 and haar), CWT (mexh), and FWT were optimized to give the highest spectral recoveries. Calibration graphs in the linear concentration ranges of ibuprofen (12–32?mg/L) and paracetamol (20–40?mg/L) were obtained by measuring the amplitudes of the transformed signals. Our proposed spectrophotometric methods were statistically compared to HPLC in terms of precision and accuracy. PMID:24949492

Hoang, Vu Dang; Ly, Dong Thi Ha; Tho, Nguyen Huu; Minh Thi Nguyen, Hue

2014-01-01

29

UV spectrophotometric simultaneous determination of paracetamol and ibuprofen in combined tablets by derivative and wavelet transforms.  

PubMed

The application of first-order derivative and wavelet transforms to UV spectra and ratio spectra was proposed for the simultaneous determination of ibuprofen and paracetamol in their combined tablets. A new hybrid approach on the combined use of first-order derivative and wavelet transforms to spectra was also discussed. In this application, DWT (sym6 and haar), CWT (mexh), and FWT were optimized to give the highest spectral recoveries. Calibration graphs in the linear concentration ranges of ibuprofen (12-32 mg/L) and paracetamol (20-40 mg/L) were obtained by measuring the amplitudes of the transformed signals. Our proposed spectrophotometric methods were statistically compared to HPLC in terms of precision and accuracy. PMID:24949492

Hoang, Vu Dang; Ly, Dong Thi Ha; Tho, Nguyen Huu; Nguyen, Hue Minh Thi

2014-01-01

30

UV-spectrophotometric determination of imatinib mesylate and its application in solubility studies.  

PubMed

A new, simple and sensitive UV-spectrophotometric method was developed for the determination of imatinib mesylate in bulk and pharmaceutical formulations (tablets and nanoparticles). The developed spectroscopic method was validated for selectivity, linearity and range, precision, accuracy and sensitivity. The method has demonstrated excellent linearity over the range of 2.5-25 microg/mL with regression equation: absorbance (AU) = 0.047 x concentration (microg/mL) + 0.008 and r2 = 0.9998. The developed method demonstrated consistent high recoveries (99-102%) and low relative standard deviation (< 5%) at 285 nm. Moreover, the method was found to be highly sensitive with low limit of detection (0.57 microg/mL) and limit of quantitation (1.71 microg/mL). The apparent molar absorptivity and Sandell's sensitivity was found to be 2.75 x 10(3) L/M cm and 2.15 microg/cm2 respectively. The validated method was successfully employed for the drug content analysis from tablets and nanoparticles preparations. Additionally, the method was successfully employed for pH metric solubility analysis of the drug. PMID:18819515

Bende, G; Kollipara, S; Sekar, V; Saha, R

2008-09-01

31

Simple Spectrophotometric Methods for Standardizing Ayurvedic Formulation  

PubMed Central

Traditional medicines are effective but the standardization of Ayurvedic formulations is essential in order to assess the quality of drugs, based on the concentration of their active principles. Department of AYUSH has given preliminary guidelines for standardizing these conventional formulations, for uniformity of batches in production of Ayurvedic formulation and it is necessary to develop methods for evaluation. The present work is an attempt to standardize asav-arishta, the traditional Ayurvedic formulation using simple, non-expensive spectrophotometric methods. The various parameters performed included total phenolics, total flavonoids, total alkaloids and total saponins, also included pH, sugar %, alcohol content and specific gravity. The results obtained may be considered as tools for assistance to the regulatory authorities, scientific organizations and manufacturers for developing standards. PMID:23325998

Vador, N.; Vador, B.; Hole, Rupali

2012-01-01

32

UV-Vis Spectrophotometrical and Analytical Methodology for the Determination of Singlet Oxygen in New Antibacterials Drugs  

PubMed Central

We have determined and quantified spectrophotometrically the capacity of producing reactive oxygen species (ROS) as 1O2 during the photolysis with UV-A light of 5 new synthesized naphthyl ester derivates of well-known quinolone antibacterials (nalidixic acid (1), cinoxacin (2), norfloxacin (3), ciprofloxacin (4) and enoxacin (5)). The ability of the naphthyl ester derivatives (6–10) to generate singlet oxygen were detecting and for the first time quantified by the histidine assay, a sensitive, fast and inexpensive method. The following tendency of generation of singlet oxygen was observed: compounds 7 > 10 > 6 > 8 > 9 >> parent drugs 1–5. PMID:19662185

Zoltan, Tamara; Vargas, Franklin; Izzo, Carla

2007-01-01

33

Spectrophotometric method for the determination, validation, spectroscopic and thermal analysis of diphenhydramine in pharmaceutical preparation  

Microsoft Academic Search

A sensitive, simple and rapid spectrophotometric method was developed for the determination of diphenhydramine in pharmaceutical preparation. The method was based on the charge-transfer complex of the drug, as n-electron donor, with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), as ?-acceptor. The formation of this complex was also confirmed by UV–vis, FTIR and 1H NMR spectra techniques and thermal analysis. The proposed method was validated

Sevgi Tatar Ulu; Fikriye Tuncel Elmali

2010-01-01

34

Simple spectrophotometric method for estimation of disodium edetate in topical gel formulations  

PubMed Central

A simple, sensitive, cost-effective and reproducible UV-spectrophotometric method has been developed and validated for the estimation of disodium edetate in topical gel formulations. Solution of disodium edetate reacts with ferric chloride to form complex in 0.1 N HCl giving ?max at 270 nm. Beer's law was obeyed in the concentration range of 5–50 ?g/mL (r2= 0.9997). The limit of detection and limit of quantitation were found to be 1.190 and 3.608 ?g/mL, respectively. The results show that the procedure is accurate, precise, and reproducible (relative standard deviation < 1%), while being simple and less time consuming. The study concluded that the UV-spectrophotometric method could be used for the quantification of disodium edetate in pure form as well as in pharmaceutical formulations. PMID:23781446

Kamboj, Sunil; Sharma, Deepak; Nair, Anroop B.; Kamboj, Suman; Sharma, Rakesh Kumar; Ali, Javed; Pramod, K; Ansari, S. H.

2011-01-01

35

UV Spectrophotometric Determination and Validation of Hydroquinone in Liposome  

PubMed Central

The method has been developed and validated for the determination of hydroquinone in liposomal formulation. The samples were dissolved in methanol and evaluated in 293 nm. The validation parameters such as linearity, accuracy, precision, specificity, limit of detection (LOD) and limit of quantitation (LOQ) were determined. The calibration curve was linear in 1-50 µg/mL range of hydroquinone analyte with a regression coefficient of 0.9998. This study showed that the liposomal hydroquinone composed of phospholipid (7.8 %), cholesterol (1.5 %), alpha ketopherol (0.17 %) and hydroquinone (0.5 %) did not absorb wavelength of 293 nm if it diluted 500 times by methanol. The concentration of hydroquinone reached 10 µg/mL after 500 times of dilution. Furthermore, various validation parameters as per ICH Q2B guideline were tested and found accordingly. The recovery percentages of liposomal hydroquinone were found 102 ± 0.8, 99 ± 0.2 and 98 ± 0.4 for 80%, 100% and 120% respectively. The relative standard deviation values of inter and intra-day precisions were <%2. LOD and LOQ were 0.24 and 0.72 µg/mL respectively.

Khoshneviszadeh, Rabea; Fazly Bazzaz, Bibi Sedigheh; Housaindokht, Mohammad Reza; Ebrahim-Habibi, Azadeh; Rajabi, Omid

2015-01-01

36

Validated chromatographic and spectrophotometric methods for analysis of some amoebicide drugs in their combined pharmaceutical preparation.  

PubMed

This work is concerned with development and validation of chromatographic and spectrophotometric methods for analysis of mebeverine HCl (MEH), diloxanide furoate (DF) and metronidazole (MET) in Dimetrol® tablets - spectrophotometric and RP-HPLC methods using UV detection. The developed spectrophotometric methods depend on determination of MEH and DF in the combined dosage form using the successive derivative ratio spectra method which depends on derivatization of the obtained ratio spectra in two steps using methanol as a solvent and measuring MEH at 226.4-232.2 nm (peak to peak) and DF at 260.6-264.8 nm (peak to peak). While MET concentrations were determined using first derivative (1D) at ? = 327 nm using the same solvent. The chromatographic method depends on HPLC separation on ODS column and elution with a mobile phase consisting water: methanol: triethylamine (25: 75: 0.5, by volume, orthophosphoric acid to pH =4). Pumping the mobile phase at 0.7 ml min-1 with UV at 230 nm. Factors affecting the developed methods were studied and optimized, moreover, they have been validated as per ICH guideline and the results demonstrated that the suggested methods are reproducible, reliable and can be applied for routine use with short time of analysis. Statistical analysis of the two developed methods with each other using F and student's-t tests showed no significant difference. PMID:23261745

Abdelaleem, Eglal Adelhamid; Abdelwahab, Nada Sayed

2013-01-01

37

Sensitive spectrophotometric method for the determination of indomethacin in capsules  

Microsoft Academic Search

A simple, sensitive and selective spectrophotometric method for the determination of indomethacin (INM) either in pure form or in capsules is described. The method is based on the coupling reaction of hydrolyzed INM with diazotized p-phenylenediamine dihydrochloride (PPDD) in sulphuric acid medium to give a red coloured product having the absorption maximum at 510 nm. The product is stable for

P Nagaraja; R. A Vasantha; H. S Yathirajan

2003-01-01

38

Spectrophotometric method for determination of tocopherol in red blood cells  

Microsoft Academic Search

A relatively rapid procedure is described for the spectrophotometric determination of total tocopherol in red blood cells (RBC) based on a modification of the original Em- merie-Engel reaction. The critical feature in this method is the presence of a large amount of an added antioxidant, pyrogallol or ascorbic acid, during the saponification and extraction stages and the use of thin-layer

Herbert J. Kayden; Ching-Kuang Chow; Loring K. Bjornson

39

Flow Injection Catalytic Spectrophotometric Method for the Determination of Permanganate  

Microsoft Academic Search

A novel flow injection spectrophotometric catalytic method is developed for the determination of permanganate. The method is based on the catalysis by permanganate of the periodate oxidation of the 1,10-phenanthroline-iron(II) complex in the presence of perchloric acid. The calibration graph is linear over the range 0.05-0.4 ?g ml?1, with a mid-range rsd of 2% (n = 10). The detection limit

A. M. Almuaibed; A. Townshend

1995-01-01

40

Simple Spectrophotometric Method for the Quantitative Determination of Uranium  

Microsoft Academic Search

A selective, reproducible, and sensitive spectrophotometric method for uranyl determination was developed. The method is based on the selective complexation reaction of ions with 2-(2-benzothiazolylazo)phenol(I), -4-methoxyphenol (II), and -3-hydroxyphenol(III) in the presence of sodium lauryl sulphate. The potentiality of the prepared reagents as new chromogenic ones for the determination of ions are studied by extensive investigations of the optimum conditions

A. S. Amin; E. H. El-Mossalamy

2003-01-01

41

Sensitive spectrophotometric methods for the determination of pindolol  

Microsoft Academic Search

Two simple, sensitive and reproducible visible spectrophotometric methods for the determination of Pindolol in amounts as low as 1 µg are described. The first method is based on the oxidation of Pindolol by sodium nitrite under acidic conditions and the coupling of the oxidised intermediate withN-1-(naphthyl)ethylenediamine dihydrochloride (NED) to the colored product. The spectrum of the colored solution is strongly

Chilukuri S. P. Sastry; Ammanamanchi Sailaja; Tippanu Thirupathi Rao

1992-01-01

42

Validated spectrophotometric methods for the estimation of moxifloxacin in bulk and pharmaceutical formulations  

Microsoft Academic Search

New, simple, cost effective, accurate and reproducible UV-spectrophotometric methods were developed and validated for the estimation of moxifloxacin in bulk and pharmaceutical formulations. Moxifloxacin was estimated at 296nm in 0.1N hydrochloric acid (pH 1.2) and at 289nm in phosphate buffer (pH 7.4). Beer's law was obeyed in the concentration range of 1–12?gml?1 (r2=0.9999) in hydrochloric acid and 1–14?gml?1 (r2=0.9998) in

Sanjay K. Motwani; Shruti Chopra; Farhan J. Ahmad; Roop K. Khar

2007-01-01

43

Spectrophotometric method for the determination of paracetamol and phenacetin  

Microsoft Academic Search

A rapid, sensitive and simple spectrophotometric method is proposed for the determination of hydrolysis products of paracetamol (PRL) and phenacetin (PHN) with sodium 1,2-naphthoquinone-4-sulphonate and cetyltrimethyl ammonium bromide (CTA) in alkaline medium. The absorbances are measured at 570 and 500 nm and the molar absorptivities found to be 1.118×104 and 4.54×103 l mol?1 cm?1 for PRL and PHN, respectively. The

P. Nagaraja; K. C. Srinivasa Murthy; K. S. Rangappa

1998-01-01

44

UV spectrophotometric simultaneous determination of cefoperazone and sulbactam in pharmaceutical formulations by derivative, Fourier and wavelet transforms.  

PubMed

Signal processing methods based on the use of derivative, Fourier and wavelet transforms were proposed for the spectrophotometric simultaneous determination of cefoperazone and sulbactam in powders for injection. These transforms were successfully applied to UV spectra and ratio spectra to find suitable working wavelengths. Wavelet signal processing was proved to have distinct advantages (i.e. higher peak intensity obtained, additional smooth function and scaling factor process eliminated) over derivative and Fourier transforms. Especially, a better resolution of spectral overlapping bands was obtained by the use of double signal transform in the sequences such as (i) spectra pre-processed by Fractional Wavelet Transform and subsequently subjected to Continuous Wavelet Transform or Discrete Wavelet Transform, and (ii) derivative - wavelet transforms combined. Calibration graphs for cefoperazone and sulbactam were recorded for the range 10-35 mg/L. Good accuracy and precision were reported for all proposed methods by analyzing synthetic mixtures of cefoperazone and sulbactam. Furthermore, these methods were statistically comparable to RP-HPLC. PMID:24374557

Hoang, Vu Dang; Loan, Nguyen Thi; Tho, Vu Thi; Nguyen, Hue Minh Thi

2014-01-01

45

Development and validation of UV-Visible spectrophotometric baseline manipulation methodology for simultaneous analysis of drotraverine and etoricoxib in pharmaceutical dosage forms  

PubMed Central

Introduction: A simple, economical, precise, and accurate new UV spectrophotometric baseline manipulation methodology for simultaneous determination of drotaverine (DRT) and etoricoxib (ETR) in a combined tablet dosage form has been developed. Materials and Methods: The method is based on baseline manipulation (difference) spectroscopy where the amplitudes at 274 and 351 nm were selected to determine ETR and DRT, respectively, in combined formulation and methanol was used as solvent. Both the drugs obey Beer's law in the concentration ranges of 4–20 ?g/mL for DRT and 4.5–22.5 ?g/mL for ETR. Results: The results of analysis have been validated statistically and recovery studies confirmed the accuracy and reproducibility of the proposed method which were carried out by following the ICH guidelines. Conclusion: It has been concluded that a new simple and accurate UV spectrophotometric baseline manipulation method was developed for simultaneous do not declare DRT and ETR in a combined tablet dosage form has been developed. PMID:23781465

Choudhari, Vishnu P.; Parekar, Sanket R.; Chate, Subhash G.; Bharande, Pradeep D.; Kuchekar, Bhanudas S.

2011-01-01

46

Simple, Fast and Reliable Liquid Chromatographic and Spectrophotometric Methods for the Determination of Theophylline in Urine, Saliva and Plasma Samples  

PubMed Central

In this study, a high-performance liquid chromatographic method (HPLC) and UV spectrophotometric method were developed, validated and applied for the determination of theophylline in biological fluids. Liquid- liquid extraction is performed for isolation of the drug and elimination of plasma and saliva interferences. Urine samples were applied without any extraction. The chromatographic separation was achieved on a C18 column by using 60:40 methanol:water as mobile phase under isocratic conditions at a flow rate of 0.75 mL/min with UV detection at 280 nm in HPLC method. UV spectrophotometric analysis was performed at 275 nm. The results of HPLC analysis were as follows: the limit of quantification: 1.1 µg/mL for urine, 1.9 µg/mL for saliva, 3.1 µg/mL for plasma; recovery: 94.85% for plasma, 100.45% for saliva, 101.39% for urine; intra-day precision: 0.22–2.33%, inter-day precision: 3.17-13.12%. Spectrophotometric analysis results were as follows: the limit of quantitation: 5.23 µg/mL for plasma, 8.7 µg/mL for urine; recovery: 98.27% for plasma, 95.25% for urine; intra-day precision: 2.37 – 3.00%, inter-day precision: 5.43-7.91%. It can be concluded that this validated HPLC method is easy, precise, accurate, sensitive and selective for determination of theophylline in biological samples. Also spectrophotometric analysis can be used where it can be applicable. PMID:25237338

Charehsaz, Mohammad; Gürbay, Aylin; Aydin, Ahmet; ?ahin, Gönül

2014-01-01

47

Extractive spectrophotometric method for the determination of tropicamide.  

PubMed

Two simple, rapid, and extractive spectrophotometric methods were developed for the determination of tropicamide (TPC). These methods are based on the formation of ionpair complexes between the basic nitrogen of the drug with bromocresol purple (BCP) and methyl orange (MO) in acidic buffer solution. The formed complexes were extracted with chloroform and measured at 408 and 427 nm using BCP and MO, respectively. Beer's law was obeyed in the range 1.0-16 ?g ml(-1) with correlation coefficient (n=6) ?0.9991. The molar absorpitivity, Sandell sensitivity, detection, and quantification limits were also calculated. The composition of the ion pairs was found 1:1 by Job's method. The proposed methods have been applied successfully for the analysis of TPC in pure and in its eye drops. PMID:22523460

Shoaibi, Za; Gouda, Aa

2012-01-01

48

Spectrophotometric estimation of tamsulosin hydrochloride by acid-dye method  

PubMed Central

A new spectrophotometric method for the estimation of tamsulosin hydrochloride in pharmaceutical dosage forms has been developed and validated. The method is based on reaction between drug and bromophenol blue and complex was measured at 421 nm. The slope, intercept and correlation coefficient was found to be 0.054, -0.020 and 0.999, respectively. Method was validated in terms of specificity, linearity, range, precision and accuracy. The developed method can be used to determine drug in both tablet and capsule formulations. Reaction was optimized using three parameters i.e., concentration of the dye, pH of the buffer, volume of the buffer and shaking time. Maximum stability of the chromophore was achieved by using pH 2 and 2 ml volume of buffer. Shaking time kept was 2 min and concentration of the dye used was 2 ml of 0.05% w/v solution. Method was validated in terms of linearity, precision, range, accuracy, LOD and LOQ and stochiometry of the method was also established using Mole ratio and Job's method of continuous variation. The dye benzonoid form (blue color) of dye ionized into quinonoid form (purple color) in presence of buffer and reacts with protonated form of drug in 1:1 ratio and forms an ion-pair complex (yellow color). PMID:23781431

Shrivastava, Alankar; Saxena, Prachi; Gupta, Vipin B.

2011-01-01

49

Simultaneous spectrophotometric determination of atrazine and cyanazine by chemometric methods  

NASA Astrophysics Data System (ADS)

A spectrophotometric method for the simultaneous determination of two herbicides, atrazine and cyanazine, is described for the first time based on their reaction with p-aminoacetophenone in the presence of pyridine in hydrochloric acid medium. The absorption spectra were measured in the wavelength range of 400-600 nm. The optimized method indicated that individual analytes followed Beer's law in the concentration ranges for atrazine and cyanazine were 0.2-3.5 mg L -1 and 0.3-5.0 mg L -1, and the limits of detection for atrazine and cyanazine were 0.099 and 0.15 mg L -1, respectively. The original and first-derivative absorption spectra of the binary mixtures were performed as a pre-treatment on the calibration matrices prior to the application of chemometric models such as classical least squares (CLS), principal component regression (PCR), partial least squares (PLS). The analytical results obtained by using these chemometric methods were evaluated on the basis of percent relative prediction error and recovery. It was found that the application of PCR and PLS models for first-derivative absorbance data gave the satisfactory results. The proposed methods were successfully applied for the simultaneous determination of the two herbicides in several food samples.

Zhang, Guowen; Pan, Junhui

2011-01-01

50

Simultaneous spectrophotometric determination of atrazine and cyanazine by chemometric methods.  

PubMed

A spectrophotometric method for the simultaneous determination of two herbicides, atrazine and cyanazine, is described for the first time based on their reaction with p-aminoacetophenone in the presence of pyridine in hydrochloric acid medium. The absorption spectra were measured in the wavelength range of 400-600 nm. The optimized method indicated that individual analytes followed Beer's law in the concentration ranges for atrazine and cyanazine were 0.2-3.5 mg L(-1) and 0.3-5.0 mg L(-1), and the limits of detection for atrazine and cyanazine were 0.099 and 0.15 mg L(-1), respectively. The original and first-derivative absorption spectra of the binary mixtures were performed as a pre-treatment on the calibration matrices prior to the application of chemometric models such as classical least squares (CLS), principal component regression (PCR), partial least squares (PLS). The analytical results obtained by using these chemometric methods were evaluated on the basis of percent relative prediction error and recovery. It was found that the application of PCR and PLS models for first-derivative absorbance data gave the satisfactory results. The proposed methods were successfully applied for the simultaneous determination of the two herbicides in several food samples. PMID:20974548

Zhang, Guowen; Pan, Junhui

2011-01-01

51

Investigation of combustion in a gasoline engine using spectrophotometric methods  

NASA Astrophysics Data System (ADS)

Spectrophotometric methods provide many new possibilities of investigation of combustion process in the automotive engine with spark ignition. Emission spectrum of the flames from the combustion chamber provides valuable information, which is difficult or even not accessible with the aid of other measurement methods. Spectral analysis allows to evaluate concentration of active compounds present in flames, which do not constitute final products of combustion. Concentration of radicals depends on some combustion parameters such as air-fuel ratio. The paper describes an engine test stand equipped with fiber-optic measurement system. The measurement system consists of an optical sensor mounted in the engine head, fiber-optic bundle for signal transmission, grating monochromator and photodetector. Voltage signal from the photodetector is recorded by the PC- based data acquisition system. The main aim of research was to verify usability of the designed fiber-optic measurement system in combustion diagnosis and to develop a method of evaluation of the air-fuel ratio on the base of simplified spectral analysis of the emission during combustion process in an automotive gasoline engine.

Hunicz, Jacek; Piernikarski, Dariusz

2001-08-01

52

Highly flexible UV-vis radiation sources and novel detection schemes for spectrophotometric HPLC detection.  

PubMed

The concept and performance of the first multiwavelength deep UV light-emitting-diode-based high-performance liquid chromatography (HPLC) absorbance detector are presented. In single-wavelength mode and with optical reference, the limit of detection (LOD) is comparable to conventional state-of-the-art HPLC absorbance detectors. In multiwavelength mode--at present up to eight wavelengths without optical reference--the LOD is about 10 times higher than in single-wavelength mode. Multiplexing and demultiplexing methods are used to separate chromatographic signals in multiwavelength mode and keeps the detector configuration simple and yet flexible. Depending on the operation mode, stray light is either totally negligible or controlled electronically and digitally. PMID:24377323

Kraiczek, Karsten G; Bonjour, R; Salvadé, Y; Zengerle, Roland

2014-01-21

53

Dispersive liquid-liquid microextraction of thiram followed by microvolume UV-vis spectrophotometric determination  

NASA Astrophysics Data System (ADS)

A novel and simple method for the sensitive determination of trace amounts of fungicide thiram is developed by combination of dispersive liquid-liquid microextraction (DLLME) and microvolume UV-vis spectrophotometry. The method is based on the conversion of thiram to a yellow product in the presence of ethanolic potassium hydroxide and copper sulfate, and its extraction into CCL4 using DLLME technique. In this method the ethanol existing in ethanolic KOH plays as disperser solvent and a cloudy solution is formed by injection of only CCl4 as extractant solvent into sample solution. Under the optimum conditions, the calibration graph was linear over the range of 25-1000 ng mL-1 of thiram with limit of detection of 11.5 ng mL-1. The relative standard deviation (RSD) for 100 and 500 ng mL-1 of thiram was 2.7 and 1.1% (n = 8), respectively. The proposed method was successfully applied to determination of thiram in water and plant seed samples.

Rastegarzadeh, Saadat; Pourreza, Nahid; Larki, Arash

2013-10-01

54

Dispersive liquid-liquid microextraction of thiram followed by microvolume UV-vis spectrophotometric determination.  

PubMed

A novel and simple method for the sensitive determination of trace amounts of fungicide thiram is developed by combination of dispersive liquid-liquid microextraction (DLLME) and microvolume UV-vis spectrophotometry. The method is based on the conversion of thiram to a yellow product in the presence of ethanolic potassium hydroxide and copper sulfate, and its extraction into CCL4 using DLLME technique. In this method the ethanol existing in ethanolic KOH plays as disperser solvent and a cloudy solution is formed by injection of only CCl4 as extractant solvent into sample solution. Under the optimum conditions, the calibration graph was linear over the range of 25-1000 ng mL(-1) of thiram with limit of detection of 11.5 ng mL(-1). The relative standard deviation (RSD) for 100 and 500 ng mL(-1) of thiram was 2.7 and 1.1% (n=8), respectively. The proposed method was successfully applied to determination of thiram in water and plant seed samples. PMID:23756257

Rastegarzadeh, Saadat; Pourreza, Nahid; Larki, Arash

2013-10-01

55

Spectrophotometric, spectrofluorimetric, and densitometric methods for the determination of indapamide.  

PubMed

Three sensitive spectrophotometric, spectrofluorimetric, and densitometric methods are described for the determination of indapamide. The first and second methods are based on the oxidative coupling reaction of indapamide with 3-methyl-2-benzothiazolinone hydrazone HCl (MBTH) in the presence of cerium(IV) ammonium sulfate in an acidic medium. The absorbance of the reaction product is measured at the lambdamax, 601 nm. With the same reaction, indapamide is determined by its quenching effect on the fluorescence of excess cerous ions at the emission lambdamax, 350 nm, and the excitation at lambdamax, 300 nm. The reaction conditions were optimized, and Beer's law was obeyed for indapamide at 1.2-9.6 microg/mL with mean recoveries of 99.92 +/- 0.83 and 99.97 +/- 1.11%, respectively. The third method, a stability-indicating densitometric assay, was developed for the determination of indapamide, using toluene-ethyl acetate-glacial acetic acid (69 + 30 + 1, v/v/v) as the developing system and scanning at the lambdamax, 242 nm, in the presence of the degradation product and related substance; for the indapamide concentration range of 0.6-6 microg/spot, the mean recovery was 99.73 +/- 0.71%. The proposed methods were successfully applied to the determination of indapamide in bulk powder and commercial tablets, and the results of the analysis agreed statistically with those obtained with the official method. Furthermore, the methods were validated according to the guidelines of the U.S. Pharmacopeia and also assessed by applying the standard additions technique. PMID:14632394

Youssef, Nadia F

2003-01-01

56

New, simple and validated kinetics spectrophotometric method for determination of moxifloxacine in its pharmaceutical formulations  

Microsoft Academic Search

The objective of this research was to develop a kinetic spectrophotometric method for determination of moxifloxacine (MOXF) in pure form and pharmaceutical formulations. The method was based on the formation of a colored N-vinyl chlorobenzoquinone derivative of MOXF by its reaction with 2,3,5,6-tetrachloro-1,4-benzoquinone in presence of acetaldehyde.The formation of the colored product was monitored spectrophotometrically by measuring the absorbance at

Maha A. Sultan

2009-01-01

57

Spectrophotometric and spectrofluorimetric methods for the determination of pregabalin in bulk and pharmaceutical preparation  

Microsoft Academic Search

Two new, sensitive and selective spectrofluorimetric and spectrophotometric methods have been developed for the determination of the ?-amino-n-butyric acid derivative pregabalin (PGB) in bulk drug and capsule. Pregabalin, as a primary amine compound, reacts with 7-chloro-4-nitrobenzofurazon (NBD-Cl) which is a highly sensitive fluorogenic and chromogenic reagent used in many investigations. According to this fact, spectrophotometric and spectrofluorimetric methods for the

Arma?an Önal; Olcay Sagirli

2009-01-01

58

QUANTITATIVE DETERMINATION OF DIAZEPAM IN PHARMACEUTICAL PREPARATION BY USING A NEW EXTRACTIVE-SPECTROPHOTOMETRIC METHOD  

Microsoft Academic Search

A simple and sensitive extraction-spectrophotometric method in the visible region is described for the determination of diazepam in bulk sample and pharmaceutical formulations. The method is based on 1 : 1 ion-association complex formation with the acidic dye, bromocresol green at pH 3.5, which is extractable into chloroform from the aqueous phase. Spectrophotometric measurement was done at 410 nm. Different variable affecting the

Susan Sadeghi; Rozita Takjoo; Soheila Haghgoo

2002-01-01

59

Spectrophotometric and spectrofluorimetric methods for analysis of tramadol, acebutolol and dothiepin in pharmaceutical preparations  

Microsoft Academic Search

Sensitive spectrophotometric and spectrofluorimetric methods are described for the determination of tramadol, acebutolol and dothiepin (dosulepin) hydrochlorides. The two methods are based on the condensation of the cited drugs with the mixed anhydrides of malonic and acetic acids at 60°C for 25–40min. The coloured condensation products are suitable for the spectrophotometric and spectrofluorimetric determination at 329–333 and 431–434nm (excitation at

Hisham E. Abdellatef; Magda M. El-Henawee; Heba M. El-Sayed; Magda M. Ayad

2006-01-01

60

Determination of semduramicin in poultry feed additive, premixture and compound feed by liquid chromatography and UV spectrophotometric detection after post-column derivatisation.  

PubMed

A new, simple and fit for purpose method based on liquid chromatography with UV spectrophotometric detection and post-column derivatisation (LC-UV-PCD) for the determination of semduramicin in poultry compound feed, premixtures and feed additive as well as its discrimination from other coccidiostats in poultry compound feed has been developed and single-laboratory validated. The concentration levels of the target analyte at which the validation experiments have been carried out varied between 12.8 and 51.3 mg kg(-1) in compound feed, covering the authorised levels of semduramicin according to European Union legislation. Furthermore, the method has been validated for a premixture sample containing semduramicin at 3 g kg(-1) and the feed additive containing semduramicin at 51 g kg(-1). The method developed involved a simple extraction of the coccidiostats with acetonitrile from the feed samples followed by a filtration of the supernatants. The resulting supernatants were submitted to chromatographic analysis. When analysing the feed additive and the premixture samples, the extraction solution was appropriately diluted prior to LC-UV-PCD analysis. The analytes were quantified through an external calibration curve prepared with pure semduramicin standards. The relative standard deviations for repeatability and for intermediate precision varied from 2.4 to 8.8% and from 2.6 to 8.8%, respectively, and the values for the relative recovery rate ranged from 89 to 95%. The limit of detection (LOD) and limit of quantification (LOQ) were estimated to be below 1 mg kg(-1) and 3 mg kg(-1), respectively. Moreover, the results showed a comparable performance profile, when using methyl isobutyl ketone instead of acetonitrile as extraction solvent.Based on the obtained method performance characteristics, the method is considered suitable for the determination of semduramicin in poultry compound feed at authorised level, in premixtures and in the feed additive, hence allowing the enforcement of the European Union legislation regarding the control and the monitoring in feedingstuffs. PMID:22169468

Vincent, Ursula; Serano, Federica; de la Huebra, María José González; von Holst, Christoph

2012-03-01

61

Spectrophotometric methods for the determination of letrozole in bulk and pharmaceutical dosage forms.  

PubMed

Ultraviolet (UV), first derivative, second derivative, and AUC-spectrophotometric methods for the determination of letrozole in pharmaceutical formulations have been developed. For UV-spectrophotometry, the standard solutions were measured at 240.0 nm. The linearity ranges were found to be 0.25-20.0 ?gml(-1) in methanol and the regression equation was A=1.20×10(-1)C+2.22×10(-2)(r(2)=0.9994). For the first derivative spectrophotometry, the response (dA/d?) of standard solutions was measured at 224.0 nm. The calibration curve was constructed by plotting dA/d? values against concentrations 0.25-20.0 ?gml(-1), of letrozole. The regression equation of the linear calibration graph was calculated as D(1)=3.89×10(-3)C+1.85×10(-4)(r(2)=0.9987). For the second derivative spectrophotometry, the response (d(2)A/d?(2)) of standard solutions was measured at 241.0 nm. The calibration curve was constructed by plotting d(2)A/d?(2) values against concentrations 0.5-20.0 ?gml(-1) of letrozole standards in methanol. The regression equation of the linear calibration graph was calculated as D(2)=-1.59×10(-3)C-4.66×10(-4)(r(2)=0.9985). The AUC-spectrophotometric method was based on the calculation of Area under Curve (AUC), for analysis of letrozole in the wavelength range of 235.0-245.0 nm. The calibration curve was constructed by plotting AUC values against concentrations 0.25-20.0 ?gml(-1), of letrozole. The regression equation of the linear calibration graph was calculated as AUC=1.132C+0.2153 (r(2)=0.9994). The methods were validated by following the analytical performance parameters suggested by the International Conference on Harmonization (ICH). All validation parameters were within the acceptable range. The developed methods were successfully applied to estimate the amount of letrozole in pharmaceutical formulations. PMID:22247870

Acharjya, Sasmita Kumari; Mallick, Priyambada; Panda, Pinakini; Kumar, K Ravi; Annapurna, M Mathrusri

2010-07-01

62

Standardization of spectrophotometric methods for determination of polyunsaturated fatty acids using pure natural acids  

Microsoft Academic Search

Summary  Spectrophotometric methods of analysis for the polyunsaturated constituents of oils and fats have been carefully restandardized\\u000a for several conditions of alkali-isomerization, using purified methyl esters of linoleic, linolenic, and arachidonic acids\\u000a prepared by physical rather than by chemical means. A number of vegetable oil and animal fat samples were subjected to spectrophotometric\\u000a analysis, and the results based on natural and

B. A. Brice; M. L. Swain; S. F. Herb; P. L. Nichols; R. W. Riemenschneider

1952-01-01

63

A New Extractive-spectrophotometric Method for the Determination of Ketoconazole from Pharmaceutical Preparations  

Microsoft Academic Search

An extraction-spectrophotometric method for the determination of trace amounts of ketoconazole is described. Ketoconazole is effectively extracted as a 1:1 ion-pair complex with picric acid at pH 2.5 into chloroform, followed by spectrophotometric determination at 410 nm. Beer's law is obeyed over the range 1-58 ?g ml and the Sandell sensitivity for 0.001 absorbance unit is 57 ng cm. The

Susan Sadeghi; Mojtaba Shamsipur

1998-01-01

64

Spectrophotometric methods for sertraline hydrochloride and\\/or clidinium bromide determination in bulk and pharmaceutical preparations  

Microsoft Academic Search

A spectrophotometric procedure for the determination of sertraline hydrochloride (Sert) and\\/or clidinium bromide (Clid) in\\u000a bulk sample and in dosage forms was developed. The purpose of this work was to develop a rapid, simple, inexpensive, precise,\\u000a and accurate visible spectrophotometric method. The procedure is based on formation of an ion-pair complex by their reaction\\u000a with bromocresol green (BCG), bromophenol blue

Alaa S. Amin; Hassan A. Dessouki; Moustafa M. Moustafa; Mohammed S. Ghoname

2009-01-01

65

Correlation of Two Anthocyanin Quantification Methods: HPLC and Spectrophotometric Methods  

Technology Transfer Automated Retrieval System (TEKTRAN)

The pH differential method and HPLC are methods that are commonly used by researchers and the food industry for quantifying anthocyanins in a sample. This study was conducted to establish a relationship between the two analytical methods. Seven juice samples containing an array of different individu...

66

Validation of different spectrophotometric methods for determination of vildagliptin and metformin in binary mixture  

NASA Astrophysics Data System (ADS)

New, simple, specific, accurate, precise and reproducible spectrophotometric methods have been developed and subsequently validated for determination of vildagliptin (VLG) and metformin (MET) in binary mixture. Zero order spectrophotometric method was the first method used for determination of MET in the range of 2-12 ?g mL-1 by measuring the absorbance at 237.6 nm. The second method was derivative spectrophotometric technique; utilized for determination of MET at 247.4 nm, in the range of 1-12 ?g mL-1. Derivative ratio spectrophotometric method was the third technique; used for determination of VLG in the range of 4-24 ?g mL-1 at 265.8 nm. Fourth and fifth methods adopted for determination of VLG in the range of 4-24 ?g mL-1; were ratio subtraction and mean centering spectrophotometric methods, respectively. All the results were statistically compared with the reported methods, using one-way analysis of variance (ANOVA). The developed methods were satisfactorily applied to analysis of the investigated drugs and proved to be specific and accurate for quality control of them in pharmaceutical dosage forms.

Abdel-Ghany, Maha F.; Abdel-Aziz, Omar; Ayad, Miriam F.; Tadros, Mariam M.

67

Determination of mirtazapine in tablets by UV spectrophotometric and derivative spectrophotometric methods  

Microsoft Academic Search

Mirtazapine, 1, 2, 3, 4, 10, 14b-hexahydro-2-methyl-pyrazino [2, 1-a] pyrido [2, 3-c] [G.L. Stimmel, J.A. Dopheide and S.M. Stahl, Pharmacotheraphy 17(1) (1997) 10] benzazepine, is a new and well tolerated antidepressant. It blocks pre-synaptic ?2-adrenergic receptors and postsynaptic serotonin type 2 and type 3 receptors. The drug is rapid and completely absorbed after oral administration. Mirtazapine was analyzed by HPLC

N. Kara?en; S. Altinöz

2000-01-01

68

Simple Spectrophotometric Methods for the Determination of Sulfamethaxazole in Pharmaceuticals Using Folinciocalteau and Orcinol as Reagents  

Microsoft Academic Search

Two simple, sensitive and reproducible spectrophotometric methods (Method A and Method B) were developed for the determination of sulfamethaxazole in bulk and in dosage forms. Method A is based reduction of phosphomolybdic acid present in Folin Ciocalteau reagent by the drug sulfamethaxazole in the presence of sodium carbonate to form a blue colored chromogen having maximum absorption at 760 nm.

G VIJAYA RAJA; C BALA SEKARAN; D. WINNIE TEJA; B MADHURI; B JAYASREE

69

Spectrophotometric methods for the determination of ritodrine hydrochloride and its application to pharmaceutical preparations  

Microsoft Academic Search

Two simple and sensitive spectrophotometric methods are described for the determination of ritodrine hydrochloride (RTH) in both pure and dosage forms. The methods are based on the interaction of diazotised p-nitroaniline (DPNA) and sulphanilic acid (DSNA) with RTH in an alkaline medium. The resulting azo dyes are measured at 480 nm (for the DPNA method) and at 440 nm (for

Hosakere D. Revanasiddappa; Bochhegowda Manju

2001-01-01

70

Spectrophotometric methods for determination of enalapril and timolol in bulk and in drug formulations  

Microsoft Academic Search

Two simple and accurate spectrophotometric methods for determination of timolol and enalapril maleate are described. The first method is based on chelate formation with palladium(II) chloride in buffered medium. The second method is based on the formation of the colored complex between palladium(II), eosin, and the two cited drugs using methylcellulose as surfactant to increase the solubility and intensity of

Magda M. Ayad; Abdalla Shalaby; Hisham E. Abdellatef; Mervat M. Hosny

2003-01-01

71

Selective and sensitive spectrophotometric method for determination of sub-micro-molar amounts of aluminium ion.  

PubMed

A simple and accurate spectrophotometric method for determination of trace and ultra-trace amounts of Al3+ ion in tap and wastewater sample has been described. Using the eriochrome cyanine R (ECR) in the presence of N,N-dodecyltrimethylammonium bromide (DTAB) as cationic surfactant spectrophotometric determination of Al3+ ion has been carried out. The Beer's law is obeyed over the concentration range of 4-400 ng mL(-1) of Al3+ ion with the detection limits of 0.14 ng mL(-1), while the molar absorptivity of complexes is 1.19x10(5) L mol(-1) cm(-1). The influence of type and amount of surfactant, pH, and amount of ligand on sensitivity of spectrophotometric method were optimized. The method has been successfully applied for Al3+ ion determination in real sample. PMID:17683861

Shokrollahi, A; Ghaedi, M; Niband, M S; Rajabi, H R

2008-03-01

72

Spectrophotometric Determination of Tetracyclines in Pure Form and in Pharmaceutical Preparations, by a Molybdenum Blue Method  

Microsoft Academic Search

A new and sensitive spectrophotometric method has been developed for the determination of tetracyclines either in a pure form or in Pharmaceuticals, by a molybdenum blue method. The procedure is based on the observation that, in sulphuric acid medium, tetracyclines reduce ammonium molybdate to molybdenum blue, the absorbance of which is proportional to the amount of antibiotic present. The variables

Basilio Morelli; Pasquale Peluso

1985-01-01

73

An Improved Spectrophotometric Method for Determination of Penicillins Alone and in Pharmaceutical Dosage Forms  

Microsoft Academic Search

A new spectrophotometric method for determining penicillins has been developed. A known volume of the penicillin solution is heated at 95[ddot]C for 70 min with ammonium molybdate, in sulphuric acid medium and the absorbance of the blue species formed is measured at 670 nm. The method has been successfully applied for the determination of thirteen commercially available penicillins. Beer's law

Basilio Morelli; Marina Mariani; Mariateresa Gesmundo

1987-01-01

74

New spectrophotometric method for the determination of flutamide in pharmaceutical preparations  

Microsoft Academic Search

A sensitive and simple spectrophotometric method for the determinations of reduction product of flutamide (FLA) is described. The method is based on the interaction of diazotized flutamide reduction product with N-(1-naphthyl) ethylenediamine dihydrochloride (NEDA) in neutral or resorcinol (RSL) in alkaline medium. Absorbance of the resulting chromophores is measured at 525 or 480 nm, respectively, and is stable for at

P Nagaraja; K. R Sunitha; M. F Silwadi

2000-01-01

75

Traceability methods comparison of broadband UV radiometers  

NASA Astrophysics Data System (ADS)

Broadband UV radiometers are widely used for measuring UV irradiance or radiant exposure in various areas of health, industry, and science, such as in weather aging of materials, semiconductor lithography, non-destructive testing, UV curing, catalytic process, environmental monitoring, atmospheric research, water purification, medical diagnostics and therapy, space-based astrophysical observations and other applications. The accuracy of measurement is influenced by many factors such as the characteristics of the radiometer, operating conditions, environmental conditions and the UV sources to be measured. Due to the lack of spectral resolving power, significant measurement errors may occur if the radiometer has poor quality. Five different calibration and traceability methods of UV radiometers were realized and analyzed at National Institute of Metrology (NIM), including absolute spectral irradiance method based on standard lamps, absolute spectral power responsivity method of detectors, absolute thermoelectric radiometer method, electrically calibrated pyroelectric radiometer method and method of comparing with the standard radiometer. The above methods were used to realize the irradiance responsivity of a broadband UVA meter independently. Compared to absolute spectral irradiance method based on standard lamps, relative deviation of these traceability methods are 0%, 0.18%, 2.50%, -3.04% and 4.11% respectively. Absolute spectral power responsivity method of detectors is adopted by the most national metrology institute to realize UV irradiance responsivity. The deviation of absolute thermoelectric radiometer method results from poor signal-to-noise of the combination of radiation source and a UV filter, near to the sensitivity limit of the absolute radiometer. The largest deviation of method of comparing with the standard radiometer comes from different response wavelength, different receiving area between the standard radiometer and the test radiometer. Spectral irradiance method based on standard lamps is the principal traceability method of NIM tracing to the national spectral irradiance primary standard directly. This method was proved by international comparison of "Irradiance Responsivity of UVA Detectors APMP PR-S1". The comparison results showed that the consistency between the NIMs' value and the international reference one is the best among the seven participants. On the basis of the above theories and methods, the uncertainty of broadband ultraviolet irradiance standard under the defined conditions was cut down to 2.0% (k=1) from 10% (k=1).

Dai, Caihong; Huang, Bo; Wu, Zhifeng; OuYang, Huiquan; Yu, Jialin

2011-11-01

76

Validated spectrophotometric methods for the estimation of moxifloxacin in bulk and pharmaceutical formulations  

NASA Astrophysics Data System (ADS)

New, simple, cost effective, accurate and reproducible UV-spectrophotometric methods were developed and validated for the estimation of moxifloxacin in bulk and pharmaceutical formulations. Moxifloxacin was estimated at 296 nm in 0.1N hydrochloric acid (pH 1.2) and at 289 nm in phosphate buffer (pH 7.4). Beer's law was obeyed in the concentration range of 1-12 ?g ml -1 ( r2 = 0.9999) in hydrochloric acid and 1-14 ?g ml -1 ( r2 = 0.9998) in the phosphate buffer medium. The apparent molar absorptivity and Sandell's sensitivity coefficient were found to be 4.63 × 10 4 l mol -1 cm -1 and 9.5 ng cm -2/0.001 A in hydrochloric acid; and 4.08 × 10 4 l mol -1 cm -1 and 10.8 ng cm -2/0.001 A in phosphate buffer media, respectively indicating the high sensitivity of the proposed methods. These methods were tested and validated for various parameters according to ICH guidelines. The detection and quantitation limits were found to be 0.0402, 0.1217 ?g ml -1 in hydrochloric acid and 0.0384, 0.1163 ?g ml -1 in phosphate buffer medium, respectively. The proposed methods were successfully applied for the determination of moxifloxacin in pharmaceutical formulations (tablets, i.v. infusions, eye drops and polymeric nanoparticles). The results demonstrated that the procedure is accurate, precise and reproducible (relative standard deviation <2%), while being simple, cheap and less time consuming and hence can be suitably applied for the estimation of moxifloxacin in different dosage forms and dissolution studies.

Motwani, Sanjay K.; Chopra, Shruti; Ahmad, Farhan J.; Khar, Roop K.

2007-10-01

77

Novel spectrophotometric methods for simultaneous determination of timolol and dorzolamide in their binary mixture  

NASA Astrophysics Data System (ADS)

Two smart and novel spectrophotometric methods namely; absorbance subtraction (AS) and amplitude modulation (AM) were developed and validated for the determination of a binary mixture of timolol maleate (TIM) and dorzolamide hydrochloride (DOR) in presence of benzalkonium chloride without prior separation, using unified regression equation. Additionally, simple, specific, accurate and precise spectrophotometric methods manipulating ratio spectra were developed and validated for simultaneous determination of the binary mixture namely; simultaneous ratio subtraction (SRS), ratio difference (RD), ratio subtraction (RS) coupled with extended ratio subtraction (EXRS), constant multiplication method (CM) and mean centering of ratio spectra (MCR). The proposed spectrophotometric procedures do not require any separation steps. Accuracy, precision and linearity ranges of the proposed methods were determined and the specificity was assessed by analyzing synthetic mixtures of both drugs. They were applied to their pharmaceutical formulation and the results obtained were statistically compared to that of a reported spectrophotometric method. The statistical comparison showed that there is no significant difference between the proposed methods and the reported one regarding both accuracy and precision.

Lotfy, Hayam Mahmoud; Hegazy, Maha A.; Rezk, Mamdouh R.; Omran, Yasmin Rostom

78

Novel spectrophotometric methods for simultaneous determination of timolol and dorzolamide in their binary mixture.  

PubMed

Two smart and novel spectrophotometric methods namely; absorbance subtraction (AS) and amplitude modulation (AM) were developed and validated for the determination of a binary mixture of timolol maleate (TIM) and dorzolamide hydrochloride (DOR) in presence of benzalkonium chloride without prior separation, using unified regression equation. Additionally, simple, specific, accurate and precise spectrophotometric methods manipulating ratio spectra were developed and validated for simultaneous determination of the binary mixture namely; simultaneous ratio subtraction (SRS), ratio difference (RD), ratio subtraction (RS) coupled with extended ratio subtraction (EXRS), constant multiplication method (CM) and mean centering of ratio spectra (MCR). The proposed spectrophotometric procedures do not require any separation steps. Accuracy, precision and linearity ranges of the proposed methods were determined and the specificity was assessed by analyzing synthetic mixtures of both drugs. They were applied to their pharmaceutical formulation and the results obtained were statistically compared to that of a reported spectrophotometric method. The statistical comparison showed that there is no significant difference between the proposed methods and the reported one regarding both accuracy and precision. PMID:24607469

Lotfy, Hayam Mahmoud; Hegazy, Maha A; Rezk, Mamdouh R; Omran, Yasmin Rostom

2014-05-21

79

Spectrophotometric and high performance liquid chromatographic methods for sensitive determination of bisphenol A  

NASA Astrophysics Data System (ADS)

A new spectrophotometric method for the determination of trace amounts of bisphenol A based on a diazotization-coupling reaction was developed. In acidic solution, clenbuterol was first diazotized with sodium nitrite, then coupled with bisphenol A to from an azo-compound [I] in NH3-NH4Cl buffer, which shows a maximum absorption at 410 nm. The effects of the amount of sodium nitrite, diazo reaction time, the amount of clenbuterol, coupling reaction time and coupling reaction temperature have been examined. Under the optional conditions, the determination of the linear range of bisphenol A is 0.24-8.4 ?g/mL, correlation coefficient is 0.9905 and detection limit of this method is 0.15 ?g/mL. The spectrophotometric method is simple, rapid, high sensitivity with better accuracy. High performance liquid chromatography (HPLC) technique combined with this new spectrophotometric method has been also developed for the measurement of bisphenol A. The analysis was achieved on a C18 column using water and methanol as a mobile phase and the detection was done spectrophotometrically at 410 nm. These reported methods were applied to the determination of bisphenol A in hot water in contact with commercially available table-water bottle samples.

Zhuang, Yafeng; Zhou, Meng; Gu, Jia; Li, Xiangmei

2014-03-01

80

Compatible validated spectrofluorimetric and spectrophotometric methods for determination of vildagliptin and saxagliptin by factorial design experiments.  

PubMed

Simple, selective and reproducible spectrofluorimetric and spectrophotometric methods have been developed for the determination of vildagliptin and saxagliptin in bulk and their pharmaceutical dosage forms. The first proposed spectrofluorimetric method is based on the dansylation reaction of the amino group of vildagliptin with dansyl chloride to form a highly fluorescent product. The formed product was measured spectrofluorimetrically at 455 nm after excitation at 345 nm. Beer's law was obeyed in a concentration range of 100-600 ?g ml(-1). The second proposed spectrophotometric method is based on the charge transfer complex of saxagliptin with tetrachloro-1,4-benzoquinone (p-chloranil). The formed charge transfer complex was measured spectrophotometrically at 530 nm. Beer's law was obeyed in a concentration range of 100-850 ?g ml(-1). The third proposed spectrophotometric method is based on the condensation reaction of the primary amino group of saxagliptin with formaldehyde and acetyl acetone to form a yellow colored product known as Hantzsch reaction, measured at 342.5 nm. Beer's law was obeyed in a concentration range of 50-300 ?g ml(-1). All the variables were studied to optimize the reactions' conditions using factorial design. The developed methods were validated and proved to be specific and accurate for quality control of vildagliptin and saxagliptin in their pharmaceutical dosage forms. PMID:25613694

Abdel-Aziz, Omar; Ayad, Miriam F; Tadros, Mariam M

2015-04-01

81

SPECTROPHOTOMETRIC METHOD FOR THE DETERMINATION OF LIPOXIDASE ACTIVITY: OBSERVATIONS ON UNSATURATED-FAT OXIDASE  

Microsoft Academic Search

BS>An improved spectrophotometric method for the determination of ; lipoxidase activity was developed and applied in studies of the purified enzyme ; and crude enzyme preparations from leguminous and other seeds, with linoleic acid ; as the substrate. The optimum pH was found to be crude lipoxidases from graham ; flour, soy beam meal, and hydrated mung beans, respectively. Hydrated

Surrey

1962-01-01

82

Comparison of two derivative spectrophotometric methods for the determination of ?-tocopherol in pharmaceutical preparations  

Microsoft Academic Search

Simple, sensitive and reliable derivative spectrophotometric methods were developed and validated for determination of ?-tocopherol in pharmaceutical preparations. The solutions of standard and the sample were prepared in absolute ethanol. The quantitative determination of the drug was carried out using the first derivative values measured at 284, 304 nm and the second derivative values measured at 288, 296 nm. Calibration graphs constructed

Bilal Y?lmaz; Murat Öztürk

2004-01-01

83

a Sensitive Spectrophotometric Method for Determination of Diosmin Using Sodium Nitroprusside as a Chromogenic Reagent  

Microsoft Academic Search

A simple and sensitive method for the spectrophotometric determination of diosmin has been developed, and optimum reaction conditions along with other analytical parameters have been evaluated. Diosmin, as a phenolic compound, reacts with sodium nitroprusside and hydroxylamine hydrochloride in a basic medium to give a green-colored product. At analytical wavelength of 763 nm, Beer's law is obeyed over the concentration range

Zenovia Moldovan; Hassan Y. Aboul-Enein

2011-01-01

84

Extraction-Spectrophotometric Method for the Determination of Betamethasone in Pure Form and in Pharmaceutical Formulations  

Microsoft Academic Search

A sensitive and rapid extraction-spectrophotometric method for the determination of betamethasone, based on the formation of a charge transfer complex with benzocaprol red (I) and acid ethyl blue (II) is described. The calibration graph, resulting from the measurement of the absorbance of the chloroform and benzene extracts (10 ml) at 588 and 677 nm using I and II. respectively, is

A. S. Amin; Y. M. Issa

1997-01-01

85

Spectrophotometric methods for simultaneous determination of betamethasone valerate and fusidic acid in their binary mixture.  

PubMed

Five spectrophotometric methods were successfully developed and validated for the determination of betamethasone valerate and fusidic acid in their binary mixture. Those methods are isoabsorptive point method combined with the first derivative (ISO Point - D(1)) and the recently developed and well established methods namely ratio difference (RD) and constant center coupled with spectrum subtraction (CC) methods, in addition to derivative ratio ((1)DD) and mean centering of ratio spectra (MCR). New enrichment technique called spectrum addition technique was used instead of traditional spiking technique. The proposed spectrophotometric procedures do not require any separation steps. Accuracy, precision and linearity ranges of the proposed methods were determined and the specificity was assessed by analyzing synthetic mixtures of both drugs. They were applied to their pharmaceutical formulation and the results obtained were statistically compared to that of official methods. The statistical comparison showed that there is no significant difference between the proposed methods and the official ones regarding both accuracy and precision. PMID:25615682

Lotfy, Hayam Mahmoud; Salem, Hesham; Abdelkawy, Mohammad; Samir, Ahmed

2015-04-01

86

UV-visible microscope spectrophotometric polarization and dichroism with increased discrimination power in forensic analysis  

NASA Astrophysics Data System (ADS)

Microanalysis of transfer (Trace) evidence is the application of a microscope and microscopical techniques for the collection, observation, documentation, examination, identification, and discrimination of micrometer sized particles or domains. Microscope spectrophotometry is the union of microscopy and spectroscopy for microanalysis. Analytical microspectroscopy is the science of studying the emission, reflection, transmission, and absorption of electromagnetic radiation to determine the structure or chemical composition of microscopic-size materials. Microscope spectrophotometry instrument designs have evolved from monochromatic illumination which transmitted through the microscope and sample and then is detected by a photometer detector (photomultiplier tube) to systems in which broad-band (white light) illumination falls incident upon a sample followed by a non-scanning grating spectrometer equipped with a solid-state multi-element detector. Most of these small modern spectrometers are configured with either silicon based charged-couple device detectors (200-950 nm) or InGaAs based diode array detectors (850-2300 nm) with computerized data acquisition and signal processing being common. A focus of this research was to evaluate the performance characteristics of various modern forensic (UV-Vis) microscope photometer systems as well as review early model instrumental designs. An important focus of this research was to efficiently measure ultraviolet-visible spectra of microscopically small specimens for classification, differentiation, and possibly individualization. The first stage of the project consisted of the preparation of microscope slides containing neutral density filter reference materials, molecular fluorescence reference materials, and dichroic reference materials. Upon completion of these standard slide preparations analysis began with measurements in order to evaluate figures of merit for comparison of the instruments investigated. The figures of merit investigated included: 1) wavelength accuracy, 2) wavelength precision, 3) wavelength resolution stability, 4) photometric accuracy, 5) photometric precision, 6) photometric linearity, 7) photometric noise, and 8) short-term baseline stability. In addition, intrinsic instrument polarization effects were investigated to determine the impact of these properties on spectral interpretation and data quality. Finally, a set of recommendations were developed which describe instrument performance characteristics for microscope and spectrometer features and functions, and specific instrument parameters that must be controlled in order to acquire high quality data from an ultraviolet-visible forensic microscope spectrophotometer system for increased discrimination power.

Purcell, Dale Kevin

87

Sensitive spectrophotometric methods for the determination of amoxycillin, ciprofloxacin and piroxicam in pure and pharmaceutical formulations  

Microsoft Academic Search

Two simple, sensitive and accurate spectrophotometric methods have been proposed for the determination of amoxycillin (AMX), ciprofloxacin (CPF) and piroxicam (PIR) in pure and pharmaceutical preparations. The methods are based on the measurement of absorbances of tris(o-phenanthroline) iron(II) [method A] and tris (bipyridyl) iron(II) [method B] complexes at 510 and at 522 nm, respectively. Reaction conditions have been optimized to

B. S Nagaralli; J Seetharamappa; M. B Melwanki

2002-01-01

88

Spectrophotometric and reversed-phase high-performance liquid chromatographic method for the determination of doxophylline in pharmaceutical formulations.  

PubMed

Two methods are described for determination of Doxophylline in a solid dosage form. The first method was based on ultraviolet (UV)-spectrophotometric determination of the drug. It involves absorbance measurement at 274 nm (?(max) of Doxophylline) in 0.1 N hydrochloric acid. The calibration curve was linear, with the correlation coefficient between 0.99 and 1.0 over a concentration range of 0.20-30 mg/ml for the drug. The second method was based on high-performance liquid chromatography (HPLC) separation of the drug in reverse-phase mode using the Hypersil ODS C(18) column (250 × 4.6 mm, 5 mm). The mobile phase constituted of buffer acetonitrile (80:20) and pH adjusted to 3.0, with dilute orthophosphoric acid delivered at a flow rate 1.0 ml/min. Detection was performed at 210 nm. Separation was completed within 7 min. The calibration curve was linear, with the correlation coefficient between 0.99 and 1.0 over a concentration range of 0.165-30 mg/ml for the drug. The relative standard deviation was found to be <2.0% for the UV-spectrophotometry and HPLC methods. Both these methods have been successively applied to the solid dosage pharmaceutical formulation, and were fully validated according to ICH guidelines. PMID:21042488

Joshi, Hr; Patel, Ah; Captain, Ad

2010-07-01

89

Simultaneous determination of some cholesterol-lowering drugs in their binary mixture by novel spectrophotometric methods  

NASA Astrophysics Data System (ADS)

Four simple, specific, accurate and precise spectrophotometric methods manipulating ratio spectra were developed and validated for simultaneous determination of simvastatin (SM) and ezetimibe (EZ) namely; extended ratio subtraction (EXRSM), simultaneous ratio subtraction (SRSM), ratio difference (RDSM) and absorption factor (AFM). The proposed spectrophotometric procedures do not require any preliminary separation step. The accuracy, precision and linearity ranges of the proposed methods were determined, and the methods were validated and the specificity was assessed by analyzing synthetic mixtures containing the cited drugs. The four methods were applied for the determination of the cited drugs in tablets and the obtained results were statistically compared with each other and with those of a reported HPLC method. The comparison showed that there is no significant difference between the proposed methods and the reported method regarding both accuracy and precision.

Lotfy, Hayam Mahmoud; Hegazy, Maha Abdel Monem

2013-09-01

90

Spectrophotometric methods for the determination of certain catecholamine derivatives in pharmaceutical preparations  

Microsoft Academic Search

Two simple, rapid and sensitive spectrophotometric methods for the determination of catecholamine derivatives (pyrocatechol, dopamine, levodopa and methyldopa) are developed. The first method involves the oxidation of o-dihydroxybenzene derivatives by N-bromosuccinimide followed by oxidative coupling with isoniazid leading to the formation of a red-coloured products of maximum absorbance (?max=480–490 nm). The second method is based on the formation of green

P. Nagaraja; K. C. Srinivasa Murthy; K. S. Rangappa; N. M. Made Gowda

1998-01-01

91

A Stability-Indicating Spectrophotometric Method for the Determination of Fenoterol in Pharmaceutical Preparations  

Microsoft Academic Search

A simple and highly sensitive spectrophotometric method was developed for the determination of fenoterol hydrobromide in pharmaceutical formulations. The method is based on measurement of the orange-yellow color peaking at 436 nm, produced when the drug is coupled with diazotized benzocaine in triethylamine medium. The method is applicable over the range of 0.5 – 10 ?g\\/ml, with minimum detectability of

H. A. AL-Malaq; A. A. AL-Majed; F. Belal

2000-01-01

92

First order derivative spectrophotometric and HPLC methods for determination of moexipril hydrochloride in the pure form, pharmeceutical formulations and evaluation of its stability.  

PubMed

A rapid, linear (over a concentration range of 0.00012-0.0012% and with correlation coefficient r = 0.999), accurate (an average recovery of 100%), precise (an average standard deviation < 1.5%) and economical first derivative UV spectrophotometric assay method (lambda(max) = 238 nm) was developed for the determination of moexipril hydrochloride (MOXL) in a pharmaceutical formulation. The method was investigated for its utility for the determination of MOXL in commercially available tablets and as a stability-indicative assay in solid state. The results obtained by means of the investigated method were statistically compared (t-Student test and F-Snedecor test) with the results obtained by means of the reference method--HPLC, which evidenced that both methods are equally precise and accurate. It was finally concluded that first derivative UV spectrophotometry is selective with reference to excipients used for the tablets' formulation, however, it is not selective with reference to MOXL degradation products. PMID:22594252

Stanisz, Beata; Regulska, Katarzyna; Ratajczak, Tomasz

2012-01-01

93

New calibration method for UV VIS photothermal deflection spectroscopy set-up  

NASA Astrophysics Data System (ADS)

Photothermal deflection spectroscopy has emerged as a useful technique for the determination of the absorption of materials with a small absorption coefficient. The technique offers relative values of the material absorptivity and, therefore, requires a calibration procedure in order to determine the absolute values. In this work, we present a new calibration method for a photothermal deflection spectroscopy set-up working in the UV-VIS, spectral range. The method is based on the use of reference samples with different levels of absorption. The samples, consisting of single thin films of amorphous carbon on transparent substrates, are optically characterized by means of spectrophotometric measurements. The accurate characterization of the samples enables the computation of their corresponding optical absorptivity in the PDS set-up. The calibration method is cross-checked by comparison of the measurements for the different reference samples and is finally applied to the study of the absorption of dielectric films in the UV.

Sancho-Parramon, Jordi; Ferré-Borrull, Josep; Bosch, Salvador; Krasilnikova, Anna; Bulir, Jiri

2006-10-01

94

A simple spectrophotometric method for the determination of ?-blockers in dosage forms  

Microsoft Academic Search

A simple, extraction-free spectrophotometric method is proposed for the analysis of some ?-blockers, namely atenolol, timolol and nadolol. The method is based on the interaction of the drugs in chloroform with 0.1% chloroformic solutions of acidic sulphophthalein dyes to form stable, yellow-coloured, ion-pair complexes peaking at 415nm. The dyes used were bromophenol blue (BPB), bromothymol blue (BTB) and bromocresol purple

S. M. Al-Ghannam

2006-01-01

95

New spectrophotometric methods for the quantitative determination of chloramphenicol in pharmaceuticals  

Microsoft Academic Search

Three new methods are proposed for the simple and sensitive spectrophotometric determination of chloramphenicol in pure form\\u000a and in related pharmaceutical preparations. Two methods are based on the diazotization of reduced chloramphenicol, followed\\u000a by coupling either with iminodibenzyl to give a violet colored product (?max = 590 nm) or with 3-aminophenol to produce an orange-red colored product (?max = 470

S. D. Naik; P. Nagaraja; H. S. Yathirajan; M. S. Hemanthakumar; B. M. Mohan

2006-01-01

96

A New Spectrophotometric Method for the Determination of Cerium Using Leuco Disulphine Blue  

Microsoft Academic Search

A new, simple, highly sensitive spectrophotometric method for the determination of trace amounts of cerium(IV) is described. The method is based on the oxidation of leuco disulphine blue (LDSB) to its blue form of disulphine blue by Ce(IV) in a sulfuric acid medium (pH 1.3–3.0); the absorbance of the formed dye is measured in an acetate buffer medium (pH 3.0–4.8)

H. D. Revanasiddappa; T. N. Kiran Kumar

2003-01-01

97

A new spectrophotometric method for the determination of zinc in milk and standard samples  

Microsoft Academic Search

In the present communication a simple spectrophotometric method for the determination of Zn is described. The method is based on the reaction of Zn with the newly synthesized reagent o-carboxyphenyl-diazoaminoazobenzene in an alkaline medium where the reagent is in the aci-form. The complex exhibits an absorption maximum at 530 nm and Beer's law is valid over the concentration range of

Lata Cherian; V. K. Gupta

1991-01-01

98

Application of spectrophotometric, densitometric, and HPLC techniques as stability indicating methods for determination of Zaleplon in pharmaceutical preparations  

NASA Astrophysics Data System (ADS)

Spectrophotometric, spectrodensitometric and HPLC are stability indicating methods described for determination of Zaleplon in pure and dosage forms. As Zaleplon is easily degradable, the proposed techniques in this manuscript are adopted for its determination in presence of its alkaline degradation product, namely N-[4-(3-cyano-pyrazolo[1,5a]pyridin-7-yl)-phenyl]- N-ethyl-acetamide. These approaches are successfully applied to quantify Zaleplon using the information included in the absorption spectra of appropriate solutions. The second derivative (D 2) spectrophotometric method, allows determination of Zaleplon without interference of its degradate at 235.2 nm using 0.01N HCl as a solvent with obedience to Beer's law over a concentration range of 1-10 ?g ml -1 with mean percentage recovery 100.24 ± 0.86%. The first derivative of the ratio spectra ( 1DD) based on the simultaneous use of ( 1DD) and measurement at 241.8 nm using the same solvent and over the same concentration range as (D 2) spectrophotometric method, with mean percentage recovery 99.9 ± 1.07%. The spectrodensitometric analysis allows the separation and quantitation of Zaleplon from its degradate on silica gel plates using chloroform:acetone:ammonia solution (9:1:0.2 by volume) as a mobile phase. This method depends on quantitave densitometric evaluation of thin layer chromatogram of Zaleplon at 338 nm over a concentration range of 0.2-1 ?g band -1, with mean percentage recovery 99.73 ± 1.35. Also a reversed-phase liquid chromatographic method using 5-C8 (22 cm × 4.6 mm i.d. 5 ?m particle size) column was described and validated for quantitation of Zaleplon using acetonitrile:deionised water (35:65, v/v) as a mobile phase using Paracetamol as internal standard and a flow rate of 1.5 ml min -1 with UV detection of the effluent at 232 nm at ambient temperature over a concentration range of 2-20 ?g ml -1 with mean percentage recovery 100.19 ± 1.15%. The insignificance difference of the proposed methods results with those of the reference one proved their accuracy and precision.

Metwally, Fadia H.; Abdelkawy, M.; Abdelwahab, Nada S.

2007-12-01

99

Development and validation of column high-performance liquid chromatographic and derivative spectrophotometric methods for determination of levofloxacin and ornidazole in combined dosage forms.  

PubMed

The manuscript describes validated reversed-phase column high-performance liquid chromatographic (RP-HPLC) and first-derivative UV spectrophotometric methods for the estimation of levofloxacin (LFX) and ornidazole (ORNI) in combined dosage forms. The RP-HPLC separation was achieved on a Phenomenex C18 column (250 mm x 4.6 mm id, 5 microm) using KH2PO4 buffer (pH 6.8)-methanol-acetonitrile (70 + 15 + 15, v/v/v) mobile phase at a flow rate of 1.5 mL/min and ambient temperature (25 +/- 2 degrees C). Quantification was achieved with photodiode array detection at 295 nm over the concentration range of 1-10 microg/mL for both LFX and ORNI, with mean recovery of 101.7 +/- 0.23 and 99.23 +/- 1.57%, respectively, by the RP-HPLC method. The derivative spectrophotometric method was based on the determination of both the drugs at their respective zero crossing point (ZCP). The first-order derivative spectra were obtained at N = 1 (scaling factor), Deltalambda = 2.0 nm (wavelength interval), and the determinations were made at 310 nm (ZCP of ORNI) for LFX and 295 nm (ZCP of LFX) for ORNI over the concentration range of 2-40 microg/mL for both LFX and ORNI. Mean recovery was 99.46 +/- 0.96 and 100.9 +/- 0.72%, respectively, by the first-derivative UV spectrophotometric method. Standard and sample solutions were prepared with methanol as the solvent in both of the methods. These methods were found to be simple, accurate, precise, and sensitive and were applicable for the simultaneous determination of LFX and ORNI in combined dosage forms. PMID:18727534

Patel, Satish A; Prajapati, Arun M; Patel, Paresh U; Patel, Natubhai J; Vaghmasi, Jayesh B

2008-01-01

100

A novel kinetic spectrophotometric method for the determination of ultra trace amount of cyanide.  

PubMed

A kinetic spectrophotometric method is described for the determination of trace levels of cyanide based on its catalytic effect on the oxidation of Janus green by ammonium peroxodisulfate in nitric acid media. The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of the Janus green at 612 nm after 4 min. The effect of reaction variables on the reaction sensitivity was investigated. Under the optimized conditions, a calibration graph from 10.0 to 500.0 ng/ml of cyanide with a detection limit of 7.0 ng/m was obtained. The proposed method is simple, sensitive and inexpensive and it was applied to directly the determination of cyanide in drinking and ground waters with the satisfactory results. PMID:20605519

Abbasi, Shahryar; Valinezhad, Rohollah; Khani, Hossein

2010-09-15

101

Spectrophotometric method for the determination of an anionic surfactant without liquid–liquid extraction  

Microsoft Academic Search

A simple method for spectrophotometric determination of an anionic surfactant (0–15?g) was studied. The ion associate formed between sodium dodecyl sulfate (SDS) and Rhodamine 6G was adsorbed onto the wall of a PTFE vessel by vigorous shaking. After the resultant solution was discarded, the ion associate was dissolved in methyl cellosolve and its absorbance measured at 534nm. The apparent molar

Minori Kamaya; Yoko Tomizawa; Kunio Nagashima

1998-01-01

102

A novel visible spectrophotometric method for the determination of ethamsylate in pharmaceutical preparations and biological samples  

Microsoft Academic Search

A highly sensitive visible spectrophotometric method has been developed to determine ethamsylate in this paper, which is based on using Cu(II) as spectroscopic probe reagent. The study indicates that in the presence of SCN? and KNO3, Cu(II) is reduced to Cu(I) by ethamsylate at pH 5.0, and the in situ formed Cu(I) reacts with SCN? to form into the white

Meiyun Zhang; Yan Zhang; Quanmin Li

2010-01-01

103

HPLC and chemometrics-assisted UV-spectroscopy methods for the simultaneous determination of ambroxol and doxycycline in capsule  

NASA Astrophysics Data System (ADS)

High-performance liquid chromatography (HPLC) and multivariate spectrophotometric methods are described for the simultaneous determination of ambroxol hydrochloride (AM) and doxycycline (DX) in combined pharmaceutical capsules. The chromatographic separation was achieved on reversed-phase C 18 analytical column with a mobile phase consisting of a mixture of 20 mM potassium dihydrogen phosphate, pH 6-acetonitrile in ratio of (1:1, v/v) and UV detection at 245 nm. Also, the resolution has been accomplished by using numerical spectrophotometric methods as classical least squares (CLS), principal component regression (PCR) and partial least squares (PLS-1) applied to the UV spectra of the mixture and graphical spectrophotometric method as first derivative of the ratio spectra ( 1DD) method. Analytical figures of merit (FOM), such as sensitivity, selectivity, analytical sensitivity, limit of quantitation and limit of detection were determined for CLS, PLS-1 and PCR methods. The proposed methods were validated and successfully applied for the analysis of pharmaceutical formulation and laboratory-prepared mixtures containing the two component combination.

Hadad, Ghada M.; El-Gindy, Alaa; Mahmoud, Waleed M. M.

2008-08-01

104

HPLC and chemometrics-assisted UV-spectroscopy methods for the simultaneous determination of ambroxol and doxycycline in capsule.  

PubMed

High-performance liquid chromatography (HPLC) and multivariate spectrophotometric methods are described for the simultaneous determination of ambroxol hydrochloride (AM) and doxycycline (DX) in combined pharmaceutical capsules. The chromatographic separation was achieved on reversed-phase C(18) analytical column with a mobile phase consisting of a mixture of 20mM potassium dihydrogen phosphate, pH 6-acetonitrile in ratio of (1:1, v/v) and UV detection at 245 nm. Also, the resolution has been accomplished by using numerical spectrophotometric methods as classical least squares (CLS), principal component regression (PCR) and partial least squares (PLS-1) applied to the UV spectra of the mixture and graphical spectrophotometric method as first derivative of the ratio spectra ((1)DD) method. Analytical figures of merit (FOM), such as sensitivity, selectivity, analytical sensitivity, limit of quantitation and limit of detection were determined for CLS, PLS-1 and PCR methods. The proposed methods were validated and successfully applied for the analysis of pharmaceutical formulation and laboratory-prepared mixtures containing the two component combination. PMID:17931962

Hadad, Ghada M; El-Gindy, Alaa; Mahmoud, Waleed M M

2008-08-01

105

Application of rapid cloud point extraction method for trace cobalt analysis coupled with spectrophotometric determination.  

PubMed

In this work, the analytical performance of conventional spectrophotometer was improved through the coupling of effective preconcentration method with spectrophotometric determination. Rapidly synergistic cloud point extraction (RS-CPE) was used to pre-concentrate ultra trace cobalt and firstly coupled with spectrophotometric determination. The developed coupling was simple, rapid and efficient. The factors influencing RS-CPE and spectrophotometer were optimized. Under the optimal conditions, the limit of detection (LOD) was 0.6?gL(-1), with sensitivity enhancement factor of 23. The relative standard deviation (RSD) for seven replicate measurements of 50?gL(-1) of cobalt was 4.3%. The recoveries for the spiked samples were in the acceptable range of 93.8-105%. PMID:23871970

Wen, Xiaodong; He, Lei; Shi, Chunsheng; Deng, Qingwen; Wang, Jiwei; Zhao, Xia

2013-11-01

106

Validated spectrophotometric methods for determination of Alendronate sodium in tablets through nucleophilic aromatic substitution reactions  

PubMed Central

Background Alendronate (ALD) is a member of the bisphosphonate family which is used for the treatment of osteoporosis, bone metastasis, Paget's disease, hypocalcaemia associated with malignancy and other conditions that feature bone fragility. ALD is a non-chromophoric compound so its determination by conventional spectrophotometric methods is not possible. So two derivatization reactions were proposed for determination of ALD through the reaction with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) and 2,4-dinitrofluorobenzene (DNFB) as chromogenic derivatizing reagents. Results Three simple and sensitive spectrophotometric methods are described for the determination of ALD. Method I is based on the reaction of ALD with NBD-Cl. Method II involved heat-catalyzed derivatization of ALD with DNFB, while, Method III is based on micellar-catalyzed reaction of the studied drug with DNFB at room temperature. The reactions products were measured at 472, 378 and 374 nm, for methods I, II and III, respectively. Beer's law was obeyed over the concentration ranges of 1.0-20.0, 4.0-40.0 and 1.5-30.0 ?g/mL with lower limits of detection of 0.09, 1.06 and 0.06 ?g/mL for Methods I, II and III, respectively. The proposed methods were applied for quantitation of the studied drug in its pure form with mean percentage recoveries of 100.47 ± 1.12, 100.17 ± 1.21 and 99.23 ± 1.26 for Methods I, II and III, respectively. Moreover the proposed methods were successfully applied for determination of ALD in different tablets. Proposals of the reactions pathways have been postulated. Conclusion The proposed spectrophotometric methods provided sensitive, specific and inexpensive analytical procedures for determination of the non-chromophoric drug alendronate either per se or in its tablet dosage forms without interference from common excipients. Graphical abstract PMID:22472190

2012-01-01

107

Validated univariate and multivariate spectrophotometric methods for the determination of pharmaceuticals mixture in complex wastewater.  

PubMed

Five, accurate, precise, and sensitive univariate and multivariate spectrophotometric methods were developed for the simultaneous determination of a ternary mixture containing Trimethoprim (TMP), Sulphamethoxazole (SMZ) and Oxytetracycline (OTC) in waste water samples collected from different cites either production wastewater or livestock wastewater after their solid phase extraction using OASIS HLB cartridges. In univariate methods OTC was determined at its ?max 355.7nm ((0)D), while (TMP) and (SMZ) were determined by three different univariate methods. Method (A) is based on successive spectrophotometric resolution technique (SSRT). The technique starts with the ratio subtraction method followed by ratio difference method for determination of TMP and SMZ. Method (B) is successive derivative ratio technique (SDR). Method (C) is mean centering of the ratio spectra (MCR). The developed multivariate methods are principle component regression (PCR) and partial least squares (PLS). The specificity of the developed methods is investigated by analyzing laboratory prepared mixtures containing different ratios of the three drugs. The obtained results are statistically compared with those obtained by the official methods, showing no significant difference with respect to accuracy and precision at p=0.05. PMID:25637816

Riad, Safaa M; Salem, Hesham; Elbalkiny, Heba T; Khattab, Fatma I

2015-04-01

108

Spectrophotometric methods for the determination of prazosin hydrochloride in tablets.  

PubMed

Four simple and sensitive methods for the assay of prazosin hydrochloride (PRH) are developed. These methods are based on the formation of coloured species by treating it either with excess N-bromosuccinimide (NBS) and determining the unconsumed NBS with p-N-methyl aminophenol sulphate (metol)-sulphanilamide (SA) reagent (method A, lambda(max) 520 nm): with 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) in the presence of eerie ammonium sulphate (CAS) (method B, lambda(max) 620 nm) or with acidic dyes such as orange-II (O-II) (method C, lambda(max) 490 nm) and alizarin violet 3B (AV-3B) (method D, lambda(max) 570 nm) under the specified experimental conditions. Regression analysis of Beer's law plot showed good correlation in the concentration range of 1.0-10.0, 2.5-25.0, 1.0-17.5 and 2.5-30.0 mug ml for methods A, B, C and D respectively. PMID:18966673

Sreedhar, K; Sastry, C S; Narayana Reddy, M; Sankar, D G

1996-11-01

109

Spectrophotometric methods for simultaneous determination of ternary mixture of amlodipine besylate, olmesartan medoxomil and hydrochlorothiazide.  

PubMed

Four, accurate, precise, and sensitive spectrophotometric methods are developed for the simultaneous determination of a ternary mixture containing amlodipine besylate (AM), olmesartan medoxomil (OL) and hydrochlorothiazide (HZ), where AM is determined at its ?(max) 364.6 nm ((0)D), while (OL) and (HZ) are determined by different methods. Method (A) depends on determining OL and HZ by measuring the second derivative of the ratio spectra ((2)DD) at 254.4 and 338.6 nm, respectively. Method (B) is first derivative of the double divisor ratio spectra (D-(1)DD) at 260.4 and 273.0 nm for OL and HZ, respectively. Method (C) based on successive spectrophotometric resolution technique (SSRT). The technique starts with the ratio subtraction method then measuring OL and HZ at their isoabsorptive point at 260.0 nm, while HZ is measured using the amplitude of first derivative at 335.2 nm. Method (D) is mean centering of the ratio spectra (MCR) at 252.0 nm and 220.0 nm for OL and HZ, respectively. The specificity of the developed methods is investigated by analyzing laboratory prepared mixtures containing different ratios of the three drugs and their combined dosage form. The obtained results are statistically compared with those obtained by the official or reported methods, showing no significant difference with respect to accuracy and precision at p=0.05. PMID:24534425

Merey, Hanan A; Ramadan, Nesrin K; Diab, Sherine S; Moustafa, Azza A

2014-05-01

110

Spectrophotometric methods for simultaneous determination of ternary mixture of amlodipine besylate, olmesartan medoxomil and hydrochlorothiazide  

NASA Astrophysics Data System (ADS)

Four, accurate, precise, and sensitive spectrophotometric methods are developed for the simultaneous determination of a ternary mixture containing amlodipine besylate (AM), olmesartan medoxomil (OL) and hydrochlorothiazide (HZ), where AM is determined at its ?max 364.6 nm (0D), while (OL) and (HZ) are determined by different methods. Method (A) depends on determining OL and HZ by measuring the second derivative of the ratio spectra (2DD) at 254.4 and 338.6 nm, respectively. Method (B) is first derivative of the double divisor ratio spectra (D-1DD) at 260.4 and 273.0 nm for OL and HZ, respectively. Method (C) based on successive spectrophotometric resolution technique (SSRT). The technique starts with the ratio subtraction method then measuring OL and HZ at their isoabsorptive point at 260.0 nm, while HZ is measured using the amplitude of first derivative at 335.2 nm. Method (D) is mean centering of the ratio spectra (MCR) at 252.0 nm and 220.0 nm for OL and HZ, respectively. The specificity of the developed methods is investigated by analyzing laboratory prepared mixtures containing different ratios of the three drugs and their combined dosage form. The obtained results are statistically compared with those obtained by the official or reported methods, showing no significant difference with respect to accuracy and precision at p = 0.05.

Merey, Hanan A.; Ramadan, Nesrin K.; Diab, Sherine S.; Moustafa, Azza A.

111

Determination of niobium in rocks by an isotope dilution spectrophotometric method  

USGS Publications Warehouse

Rocks and minerals are fused with sodium peroxide in the presence of carrierfree 95Nb. The fusion cake is leached with water and the precipitate dissolved in hydrofluoric-sulfuric acid mixture. Niobium is extracted into methyl isobutyl ketone and further purified by ion exchange. The amount of niobium is determined spectrophotometrically with 4-(2-pyridylazo)-resorcinol, and the chemical yield of the separations determined by counting 95Nb. This procedure is faster and less sensitive to interferences than previously proposed methods for determining niobium in rocks.The high purity of the separated niobium makes the method applicable to nearly all matrices. ?? 1970.

Greenland, L.P.; Campbell, E.Y.

1970-01-01

112

Comparison of HPLC, UV spectrophotometry and potentiometric titration methods for the determination of lumefantrine in pharmaceutical products.  

PubMed

This paper describes the development and evaluation of a HPLC, UV spectrophotometry and potentiometric titration methods to quantify lumefantrine in raw materials and tablets. HPLC analyses were carried out using a Symmetry C(18) column and a mobile phase composed of methanol and 0.05% trifluoroacetic acid (80:20), with a flow rate of 1.0ml/min and UV detection at 335nm. For the spectrophotometric analyses, methanol was used as solvent and the wavelength of 335nm was selected for the detection. Non-aqueous titration of lumefantrine was carried out using perchloric acid as titrant and glacial acetic acid/acetic anhydride as solvent. The end point was potentiometrically determined. The three evaluated methods showed to be adequate to quantify lumefantrine in raw materials, while HPLC and UV methods presented the most reliable results for the analyses of tablets. PMID:18571353

da Costa César, Isabela; Nogueira, Fernando Henrique Andrade; Pianetti, Gérson Antônio

2008-09-10

113

UV-fluorescence spectrophotometric assessment and characterization of dissolved fluorescent matter in coastal water of the central adriatic  

NASA Astrophysics Data System (ADS)

UV-fluorescence spectrophotometry was used to investigate dissolved fluorescent matter in coastal seawater samples from Split. Conventional and synchronous scanning modes were employed. Concentrations of dissolved fluorescent matter were estimated using calibration curves constructed from known concentrations of quinine in sulphuric acid and additionally of Suwannee River fulvic acid in Copenhague standard seawater. The results obtained during a one-year survey showed a low variability except during a phytoplankton bloom, when values were much higher. In that period the presence of aromatic systems with 3 and 4, 5 and probably 7 fused rings was also detected by a synchronous technique. The fluorescence method using calibration curves of standard solutions of quinine in sulphuric acid and SuwanneeRiver fulvic acid in standard seawater allowed rapid and sensitive assessment of these substances in seawater.

Dujmov, Jozo; Su?evi?, Perica; Antoli?, Boris

114

Extractive spectrophotometric method for the determination of atmospheric nitrogen dioxide  

NASA Astrophysics Data System (ADS)

A simple and sensitive method for the determination of oxides of nitrogen, using alkaline guaiacol as absorbing medium as well as coupling agent is proposed. The nitrite ion formed is diazotized with pnitroaniline in acidic medium and subsequently coupled with guaiacol in alkaline medium to give a red dye having ? max 505 nm and molar absorptivity of 4.8 × 10 4lmole-1cm-1. Optimum reaction conditions for diazotization, full colour development and the effect of variables have been studied. Detailed studies to check the collection efficiency and NO 4:NO -2 stoichiometric ratio have been carried out. Solvent extraction increases the sensitivity making low concentration of NO 2 determinable. Interference from common copollutants is either negligible or preventable. The method has been successfully applied for the analyses of NO 2 in environmental samples.

Baveja, Anil K.; Chaube, Abha; Gupta, V. K.

115

Titrimetric and Spectrophotometric Methods for the Assay of Ketotifen Using Cerium(IV) and Two Reagents  

PubMed Central

One titrimetric and two spectrophotometric methods are described for the determination of ketotifen fumarate (KTF) in bulk drug and in tablets using cerium(IV) as the oxidimetric agent. In titrimetry (method A), the drug was treated with a measured excess of cerium(IV) in H2SO4 medium and after a standing time of 10 min, the surplus oxidant was determined by back titration with iron(II). The spectrophotometric procedures involve addition of a known excess of cerium(IV) to KTF in acid medium followed by the determination of unreacted oxidant by reacting with either p-dimethyl amino benzaldehyde and measuring the resulting colour at 460?nm (method B) or o-dianisidine and subsequent measurement of the absorbance of coloured product at 470?nm (method C). Titrimetric assay is based on a 1?:?2 reaction stoichiometry between KTF and cerium(IV) and the method is applicable over 2–18?mg range. In spectrophotometry, regression analysis of Beer's law plots showed a good correlation in 0.4–8.0 and 0.4–10.0?g?mL?1 KTF ranges for method B and method C, respectively, and the corresponding molar absorptivity coefficients are calculated to be 4.0 × 104 and 3.7 × 104?L?mol?1?cm?1. PMID:24324496

Raghu, Madihalli Srinivas; Basavaiah, Kanakapura; Prashanth, Kudige Nagaraj; Vinay, Kanakapura Basavaiah

2013-01-01

116

Sensitive extractive spectrophotometric methods for the determination of nortriptyline hydrochloride in pharmaceutical formulations.  

PubMed

Two simple, sensitive and rapid extractive spectrophotometric methods have been developed for the assay of the antidepressant drug nortriptyline (NOR) hydrochloride in pure form and in different dosage forms. The methods involve the formation of colored ion-pairs between the drug and the complex of niobium(V)-thiocyanate (Nb-SCN) or iron(III)-thiocyanate (Fe-SCN) followed by their extraction with butanol or a mixture of butanol and chloroform and quantitative determination at 360 nm and 490 nm, using Nb-SCN and Fe-SCN, respectively. The experimental conditions were optimized to obtain the maximum colour intensity. The methods permit the determination of nortriptyline over a concentration range of 15-100 microg/ml and 5-24 microg/ml with the detection limit of 0.84 microg/ml and 0.32 microg/ml, using Nb-SCN and Fe-SCN, respectively. The proposed methods are applicable for the assay of the investigated drug in different dosage forms and the results are in good agreement with those obtained by the official and HPLC methods. No interference was observed from common excipients present in pharmaceutical formulations. The proposed procedures were applied to determine the amount of nortriptyline hydrochloride as active ingredient in the presence of its degradation product, dibenzosuberone. The extractive spectrophotometric methods can also be used to determine the amount of nortriptyline hydrochloride in tablets after its solid phase extraction (SPE). PMID:18057736

Misiuk, Wieslawa; Tykocka, Agnieszka

2007-12-01

117

Spectrophotometric and complexometric methods for the determination of thorium and fluoride using bromocresol orange reagent.  

PubMed

The ternary purple coloured complex formed between Th(4+), bromocresol orange (BCO) and cetylpyridinium bromide (CPB) in acidic medium was investigated spectrophotometrically. Results obtained revealed the formation of 1:1:1, Th:BCO:CPB complex in aqueous solution at pH approximately 0.5 with a logarithmic conditional stability constant of 12.04+/-0.1, I=0.1 at 25 degrees C. The colour of the ternary complex was used for the determination of thorium(IV) in the range of 0.02-2.6 mug ml(-1) Th(4+), =9.2x10(4) l mol(-1) cm(-1) at 560 nm. Beside its high sensitivity, the reaction was also proved to be highly selective for Th(4+). Thorium(IV) was determined in presence of great number of transition metal ions, rare earths and different anions. Th(4+) was also determined with high accuracy and precision by its titration with disodium ethylenediaminetetraacetate (Na(2)EDTA) using BCO as an indicator at pH approximately 0.5. The endpoint was detected either visually or spectrophotometrically (lambda=550 nm). The proposed procedures were successfully applied for the determination of Th(4+) in standard Th-U ores and in a series of naturally occurring ores or minerals containing thorium. A spectrophotometric method was also described for the determination of fluoride ion, which was based upon the decrease in colour intensity of the Th-BCO complex on mixing it with F(-) ion. The proposed method was convenient, rapid and sensitive for fluoride. It could be used for the determination of fluoride ion in the 0.02-3.00 mug ml(-1) range (S.D.+/-0.9%). The proposed method was successfully applied for direct determination of F(-) ion in water obtained from different origins and the results were satisfactory. PMID:18967357

Khalifa, M E; Hafez, M A

1998-11-01

118

Simultaneous determination of some anti-hypertensive drugs in their binary mixture by novel spectrophotometric methods  

NASA Astrophysics Data System (ADS)

Three simple, accurate and precise spectrophotometric methods manipulating ratio spectra were developed and validated for simultaneous determination of Irbesartan (IRB) and Hydrochlorothiazide (HCT) without prior separation namely; ratio subtraction coupled with constant multiplication (RS-CM), ratio difference (RD) and constant center (CC). The accuracy, precision and linearity ranges of the proposed methods were determined, and the methods were validated and the specificity was assessed by analyzing synthetic mixtures containing the cited drugs. The three methods were applied for the determination of the cited drugs in tablets and the obtained results were statistically compared with each other and with those of official methods. The comparison showed that there is no significant difference between the proposed methods and the official methods regarding both accuracy and precision.

Fayez, Yasmin Mohammed

2014-11-01

119

Second order advantage applied to the spectrophotometric analysis of ciprofloxacin and dexamethasone in ophthalmic drops; automatic green method using on-line photodegradation.  

PubMed

On-line photodegradation and spectrophotometric analysis assisted by multivariate curve resolution-alternating least squares (MCR-ALS) was developed the simultaneous determination of ciprofloxacin (CIP) and dexamethasone (DEX) in ophthalmic suspensions using an automated flow-batch analysis (FBA) system. CIP and DEX have strongly overlapped UV spectra. Overcoming this lack of selectivity involves augmenting data dimensionality. This could be performed by adding information about the sample photodegradation to obtain the so-called second order advantage. Commercial sample analysis was successfully performed and no statistical differences (? = 0.05) with respect to pharmacopeia methods were obtained. The proposed method offers several advantages over the methods developed to date. In agreement with the principles of green chemistry, only water was used as solvent, low amounts of waste were generated and on-line waste treatment was included in the system. Moreover, the cost per analysis was significantly reduced compared to methods that employ separative techniques. PMID:25492460

Razuc, Mariela F; Grünhut, Marcos; Garrido, Mariano; Fernández Band, Beatriz S

2014-01-01

120

Determination of lead(II) in fly ash leachate using a newly developed simple spectrophotometric method  

NASA Astrophysics Data System (ADS)

A new simple method for the spectrophotometric determination of Pb(II) in fly ash leachates was developed. These leachates tend to contain a large amount of Ca(II) and Zn(II); this interferes with spectrophotometric determination of Pb(II) when conventional colorimetric agents are used. A copolymer consisting of protoporphyrin IX disodium salt and acrylamide was synthesized as a colorimetric agent. A measuring reagent containing ethylenediamine-N,N'-dipropionic acid (EDDP) as a masking agent for Zn(II) and an appropriate amount of Ca(II) together with the copolymer was applied to determine Pb(II). The temporal change in the absorption spectrum of the measuring reagent was acquired with a newly developed portable spectrophotometer for this method. The composition of EDDP and Ca(II) in the measuring reagent was optimized to measure leachates contaminated with Ca(II) and Zn(II). The detection limit and relative standard deviation of Pb(II) measured using the optimized method were 0.05 mg L -1 and 2.3%, respectively. The tolerance limits for Ca(II) and Zn(II) contaminants, where errors of less than 10% were allowed at a concentration of 0.5 mg L -1 Pb(II), were 4000 and 4 mg L -1, respectively. The determination of Pb(II) in various samples of actual leachates from incinerator fly ash was examined with this method. The obtained values correlated well with those obtained by flame atomic absorption spectroscopy.

Asano, Takaharu; Yabusaki, Katsumi; Wang, Pi-Chao; Iwasaki, Akio

2010-02-01

121

Development and Validation of Spectrophotometric, Atomic Absorption and Kinetic Methods for Determination of Moxifloxacin Hydrochloride  

PubMed Central

Three simple spectrophotometric and atomic absorption spectrometric methods are developed and validated for the determination of moxifloxacin HCl in pure form and in pharmaceutical formulations. Method (A) is a kinetic method based on the oxidation of moxifloxacin HCl by Fe3+ ion in the presence of 1,10 o-phenanthroline (o-phen). Method (B) describes spectrophotometric procedures for determination of moxifloxacin HCl based on its ability to reduce Fe (III) to Fe (II), which was rapidly converted to the corresponding stable coloured complex after reacting with 2,2? bipyridyl (bipy). The formation of the tris-complex formed in both methods (A) and (B) were carefully studied and their absorbance were measured at 510 and 520 nm respectively. Method (C) is based on the formation of ion- pair associated between the drug and bismuth (III) tetraiodide in acidic medium to form orange—red ion-pair associates. This associate can be quantitatively determined by three different procedures. The formed precipitate is either filtered off, dissolved in acetone and quantified spectrophotometrically at 462 nm (Procedure 1), or decomposed by hydrochloric acid, and the bismuth content is determined by direct atomic absorption spectrometric (Procedure 2). Also the residual unreacted metal complex in the filtrate is determined through its metal content using indirect atomic absorption spectrometric technique (procedure 3). All the proposed methods were validated according to the International Conference on Harmonization (ICH) guidelines, the three proposed methods permit the determination of moxifloxacin HCl in the range of (0.8–6, 0.8–4) for methods A and B, (16–96, 16–96 and 16–72) for procedures 1–3 in method C. The limits of detection and quantitation were calculated, the precision of the methods were satisfactory; the values of relative standard deviations did not exceed 2%. The proposed methods were successfully applied to determine the drug in its pharmaceutical formulations without interference from the common excipients. The results obtained by the proposed methods were comparable with those obtained by the reference method. PMID:22219661

Abdellaziz, Lobna M.; Hosny, Mervat M.

2011-01-01

122

Comparison of three spectrophotometric methods for analysis of egg yolk carotenoids.  

PubMed

Carotenoids accumulated in the egg yolk are of importance for two reasons. Firstly they are important pigments influencing customer acceptance and secondly they are essential components with positive health effects either as antioxidants or as precursor of vitamin A. Different analytical methods are available to quantitatively identify carotenoids from egg yolk such as spectrophotometric methods described by AOAC (Association of Official Analytical Chemists) and HPLC (High Performance Liquid Chromatography). Both methods have in common that they are time consuming, need a laboratory environment and well trained technical operators. Recently, a rapid lab-independent spectrophotometric method (iCheck, BioAnalyt GmbH, Germany) has been introduced that claims to be less time consuming and easy to operate. The aim of the current study was therefore to compare the novel method with the two standard methods. Yolks of 80 eggs were analysed as aliquots by the three methods in parallel. While both spectrometric methods are only able measure total carotenoids as total ß-carotene, HPLC enables the determination of individual carotenoids such lutein, zeaxanthin, canthaxanthin, ß-carotene and ?-apocarotenoic ester. In general, total carotenoids levels as obtained by AOAC were in average 27% higher than those obtained by HPLC. Carotenoid values obtained by the reference methods AOAC and HPLC are highly correlated with the iCheck method with r(2) of 0.99 and 0.94 for iCheck vs. AOAC and iCheck vs. HPLC, respectively (both p<0.001). Bland Altman analysis showed that the novel iCheck method is comparable to the reference methods. In conclusion, the novel rapid and portable iCheck method is a valid and effective tool to determine total carotenoid of egg yolk under laboratory-independent conditions with little trained personal. PMID:25442548

Islam, K M S; Schweigert, F J

2015-04-01

123

A Sensitive Spectrophotometric Method for the Determination of Some Imidazoline Derivatives by 2,6-Dichlorophenol-Indophenol  

Microsoft Academic Search

A new and highly sensitive method is presented for the spectrophotometric determination of four imidazoline derivatives: antazoline hydrochloride, tolazoline hydrochloride, xylometazoline hydrochloride and naphazoline nitrate. The method is based on the reaction of the corresponding drug base with 2,6 - dichlorophenol -indophenol (DGPIP) in chloroform to give a blue chromogen exhibiting a maximum at 588 - 603nm. The method could

M. Abdel Salam; A. S. Issa; M. S. Mahrous

1986-01-01

124

p Ka determinations of xanthene derivates in aqueous solutions by multivariate analysis applied to UV-Vis spectrophotometric data  

NASA Astrophysics Data System (ADS)

Xanthenes form to an important class of dyes which are widely used. Most of them present three acid-base groups: two phenolic sites and one carboxylic site. Therefore, the p Ka determination and the attribution of each group to the corresponding p Ka value is a very important feature. Attempts to obtain reliable p Ka through the potentiometry titration and the electronic absorption spectrophotometry using the first and second orders derivative failed. Due to the close p Ka values allied to strong UV-Vis spectral overlap, multivariate analysis, a powerful chemometric method, is applied in this work. The determination was performed for eosin Y, erythrosin B, and bengal rose B, and also for other synthesized derivatives such as 2-(3,6-dihydroxy-9-acridinyl) benzoic acid, 2,4,5,7-tetranitrofluorescein, eosin methyl ester, and erythrosin methyl ester in water. These last two compounds (esters) permitted to attribute the p Ka of the phenolic group, which is not easily recognizable for some investigated dyes. Besides the p Ka determination, the chemometry allowed for estimating the electronic spectrum of some prevalent protolytic species and the substituents effects evaluation.

Batistela, Vagner Roberto; Pellosi, Diogo Silva; de Souza, Franciane Dutra; da Costa, Willian Ferreira; de Oliveira Santin, Silvana Maria; de Souza, Vagner Roberto; Caetano, Wilker; de Oliveira, Hueder Paulo Moisés; Scarminio, Ieda Spacino; Hioka, Noboru

2011-09-01

125

A sensitive spectrophotometric method for the determination of sulfonamides in pharmaceutical preparations.  

PubMed

A new, simple and sensitive spectrophotometric method for the determination of some sulfonamide drugs has been developed. The method is based on the diazotization of sulfacetamide, sulfadiazine, sulfaguanidine, sulfamerazine, sulfamethazine, sulfamethoxazole, and their coupling with 8-hydroxyquinoline in alkaline media to yield red coloured products with absorption maxima at 500 nm. Beer's law is obeyed from 0.1-7.0 microg mL-1. The limits of quantification and limits of detection were 0.11-0.18 and 0.03-0.05 microg mL-1, respectively. Intraday precision (RSD 0.1-0.5%) and accuracy (recovery 97.3--100.8%) of the developed method were evaluated. No interference was observed from common adjuvants. The method has been successfully applied to the assay of sulpha drug in pharmaceutical formulations. PMID:17878112

Nagaraja, Padmarajaiah; Naik, Shailendra D; Shrestha, Ashwinee Kumar; Shivakumar, Anantharaman

2007-09-01

126

Validation of a new 96-well plate spectrophotometric method for the quantification of compound 48/80 associated with particles.  

PubMed

A new, simple, inexpensive, and rapid 96-well plate UV spectrophotometric method was developed and validated for the quantification of compound 48/80 (C48/80) associated with particles. C48/80 was quantified at 570 nm after reaction with acetaldehyde and sodium nitroprusside in an alkaline solution (pH 9.6). The method was validated according to the recommendations of the ICH Guidelines for specificity, linearity, range, accuracy, precision, and detection and quantification limits (DL and QL). All the validation parameters were assessed in three different solvents, i.e., deionized water, blank matrix of chitosan nanoparticles, and blank matrix of chitosan/alginate nanoparticles. The method was found to be linear in the concentration range of 5 to 160 ?g/ml (R(2)>0.9994). Intraday and interday precision was adequate, with relative standard deviation lower than those given by the Horwitz equation. The mean recoveries of C48/80 from spiked samples ranged between 98.1% and 105.9% for calibration curves done with the blank matrices and between 89.3% and 103.3% for calibration curves done with water, respectively. The DL were lower than 1.01 ?g/ml and the QL were lower than 3.30 ?g/ml. The results showed that the developed method is sensitive, linear, precise, and accurate for its intended use, with the additional advantages of being cost-effective and time-effective, allowing the use of small-volume samples, and the simultaneous analysis of a large number of samples. The proposed method was already successfully applied to evaluate the loading efficacy of C48/80 chitosan-based nanoparticles and can be easily applied during the development of other C48/80-based formulations. PMID:23468340

Bento, Dulce; Borchard, Gerrit; Gonçalves, Teresa; Borges, Olga

2013-06-01

127

Extractive spectrophotometric methods for the determination of doxepin hydrochloride in pharmaceutical preparations using titanium (IV) and iron (III) thiocyanate complexes  

Microsoft Academic Search

Two simple, precise, and accurate extractive spectrophotometric methods have been developed for the determination of doxepin hydrochloride in pharmaceutical preparations. The methods are based on the formation of ion association complexes of doxepin with titanium (IV) and iron (III) thiocyanate complexes in acidic medium. The produced compounds are insoluble in water but well soluble in some organic solvents. They are

Wies?awa Misiuk

2005-01-01

128

A new sensitive and selective spectrophotometric method for the determination of catechol derivatives and its pharmaceutical preparations  

Microsoft Academic Search

A sensitive and simple spectrophotometric method for the estimation of certain catechol derivatives like pyrocatechol (PCL), dopamine hydrochloride (DPH), levodopa (LDP), methyl dopa (MDP) and adrenaline (ADH) in either pure form or in its pharmaceutical formulation is described. The method is based on the interaction of diazotised p-nitro aniline (DPNA) with catechol derivatives in presence of molybdate ions in acidic

P. Nagaraja; R. A. Vasantha; K. R. Sunitha

2001-01-01

129

Development and validation of indirect visible spectrophotometric methods for oxcarbazepine in pure and the tablet dosage form  

Microsoft Academic Search

Three simple, accurate and highly sensitive indirect spectrophotometric methods have been developed for the determination of oxcarbazepine (OXC) in both pure and in pharmaceutical preparations. The methods are based on the oxidation of oxcarbazepine by a known excess of cerium(IV) in acid medium. This was followed by the determination of unreacted cerium(IV), which oxidizes leuco dyes to colored dyes in

Hemavathi N. Deepakumari; Hosakere D. Revanasiddappa

130

Sensitive spectrophotometric method for the determination of superoxide dismutase activity in tissue extracts  

SciTech Connect

Superoxide dismutase (EC 1.15.1.1) has been assayed by a spectrophotometric method based on the inhibition of a superoxide-driven NADH oxidation. The assay consists of a purely chemical reaction sequence which involves EDTA. Mn(II), mercaptoethanol, and molecular oxygen, requiring neither auxiliary enzymes nor sophisticated equipment. The method is very flexible and rapid and is applicable with high sensitivity to the determination of both pure and crude superoxide dismutase preparations. The decrease of the rate of NADH oxidation is a function of enzyme concentration, and saturation levels are attainable. Fifty percent inhibition, corresponding to one unit of the enzyme, is produced by approximately 15 ng of pure superoxide dismutase. Experiments on rat liver cytosol have shown the specificity of the method for superoxide dismutase. Moreover, common cellular components do not interfere with the measurement, except for hemoglobin when present at relatively high concentrations. The assay is performed at physiological pH and is unaffected by catalase.

Paoletti, F.; Aldinucci, D.; Mocali, A.; Caparrini, A.

1986-05-01

131

Validated spectrophotometric methods for the simultaneous determination of telmisartan and atorvastatin in bulk and tablets  

PubMed Central

Aim: Three simple, accurate, and reproducible spectrophotometric methods have been developed and validated for simultaneous estimation of telmisartan (TELM) atorvastatin (ATV) in combined tablet dosage form. Materials and Methods: The first method is based on first-order derivative spectroscopy. The sampling wavelengths were 223 nm (zero crossing of TELM) where ATV showed considerable absorbance and 272 nm (zero crossing of ATV) where TELM showed considerable absorbance. The second method Q-analysis (absorbance ratio), involves formation of Q-absorbance equation using respective absorptivity values at 280.9 nm (isobestic point) and 296.0 nm (?max of TELM). The third method involves determination using multicomponent mode method; sampling wavelengths selected were 296.0 and 246.9 nm. Results: TELM and ATV followed linearity in the concentration range of 5–40 and 4–32 ?g/ml for method I, 5–30 ?g/ml and 2–24 ?g/ml for method II and III, respectively. Mean recoveries for all three methods were found satisfactory. All methods were validated according to International Conference on Harmonization Q2B guidelines. Conclusion: The developed methods are simple, precise, rugged, and economical. The utility of methods has been demonstrated by analysis of commercially available tablet dosage form. PMID:23781490

Ilango, Kaliappan; Kumar, Pushpangadhan S. Shiji

2012-01-01

132

UV-Vis spectrophotometric studies of self-oxidation/dissociation of quaternary ammonium permanganates (QAP) - impact of solvent polarity.  

PubMed

Self-oxidation/dissociation of some quaternary ammonium permanganates (QAPs), such as cetyltrimethylammonium permanganate (CTAP) and tetrabutylammonium permanganate (TBAP), have been studied spectrophotometrically in six different organic solvent media of different polarities wherein the compounds show good solubility and stability. The optical densities of the substrates at zero time (ODo) and first-order rate constants of dissociation (k1) have been determined from their successive scanning for 40min. At comparable experimental conditions, absorption capabilities of the substrates are compared from the ODo values in various organic media; the stability of the solutions is compared from the successive scan spectra in those media. The ODo values and the k1 values have been plotted against some solvent parameters to understand their effects on the absorbance and reactivity of the QAPs. These data are also subjected to multiple regression analysis to explain the influence of various solvent parameters on the ion-pairing properties of the substrates, thus elucidating their effects on the process of self-oxidation/dissociation of the substrates. PMID:25699691

Bank, Suraj Prakash; Guru, Partha Sarathi; Dash, Sukalyan

2015-05-01

133

Kinetic spectrophotometric methods for the determination of artificial sweetener (sucralose) in tablets.  

PubMed

Two simple and sensitive kinetic spectrophotometric methods for the determination of sucralose are described. The first method is based upon a kinetic investigation of the oxidation reaction of the drug with alkaline potassium permanganate at room temperature for a fixed time of 30 min. The absorbance of the green coloured manganate ions produced was measured at 610 nm. The second method is based on the reaction of sucralose with cerium (IV) ammonium sulfate in the presence of perchloric acid with the subsequent measurement of the excess unreacted cerium (IV) ammonium sulfate at 320 nm at a fixed time of 30 min in a thermostated water bath at 60 ± 1 °C. This principle is adopted to develop a kinetic method for sucralose determination. The absorbance concentration plots in both methods were rectilinear over the range 4-16 and 10-30 µg ml(-1) , for the first and second methods, respectively. The different experimental parameters affecting the development and stability of the colours were carefully studied and optimized. The determination of sucralose by rate constant method, fixed concentration method, and fixed-time method was also feasible with calibration equations obtained but the latter method was found to be more applicable. The two methods have been applied successfully to commercial tablets. PMID:21500365

Youssef, Rasha M; Korany, Mohamed A; Khamis, Essam F; Mahgoub, Hoda; Kamal, Miranda F

2011-04-01

134

Spectrophotometric methods for the rapid determination of menadione and menadione sodium bisulphite and their application in pharmaceutical preparations  

Microsoft Academic Search

Two simple, rapid and sensitive spectrophotometric determination of menadione and its sodium bisulphite derivative (MSB) have been carried out. The first method involves the reaction of menadione and its sodium bisulphite derivative with 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) is sodium hydroxide medium to give blue coloured product having maximum absorption at 625 nm and the coloured species is stable for more

P Nagaraja; R. A Vasantha; H. S Yathirajan

2002-01-01

135

A simple spectrophotometric method for metallothionein evaluation in marine organisms: an application to Mediterranean and Antarctic molluscs  

Microsoft Academic Search

A spectrophotometric method to evaluate the concentration of metallothioneins in the tissues of marine organisms has been developed. Metallothionein concentration was evaluated utilizing a partially purified metalloprotein fraction obtained by acidic ethanol\\/chloroform fractionation of the tissue homogenate. The procedure takes into account precautions to obtain a complete metallothionein precipitation and to avoid the oxidation of sulphydryl groups (SH), the contamination

Aldo Viarengo; Enrica Ponzano; Francesco Dondero; Rita Fabbri

1997-01-01

136

A Novel Spectrophotometric Method for Estimation of Fe in Metallurgical Samples Using Cyanex 301 as Extractant  

NASA Astrophysics Data System (ADS)

Iron(III) has been estimated spectrophotometrically at 425 nm following its quantitative extraction from Cl- medium by Cyanex 301 in redistilled colorless kerosene. Beer's law is valid provided (i) a 10-min phase agitation is allowed in extraction, (ii) [HCl] in the aqueous phase during extraction is kept at 0.10 mol/l or less, (iii) [Cyanex 301] is kept over 0.5% (v/v). It is observed that the linearity range of Beer's plot is increased with increasing (v/v)% of the Cyanex 301 used; the optimum ([Fe(III)], mg/l)/[Cyanex 301] in ((v/v)%) is 20:1. The color is stable for at least 10 days. The molar extinction coefficient ? is 7111 l/mol?cm. The method has been applied in the analysis of some metallurgical samples.

Biswas, R. K.; Karmakar, K.; Mondal, T. K.

2014-09-01

137

Development and validation of high performance liquid chromatography with a spectrophotometric detection method for the chemical purity and assay of nepafenac.  

PubMed

The study is a proposition of the application of high performance liquid chromatography (HPLC) with a spectrophotometric UV range detector to analyze the chemical purity and assay of nepafenac, an active pharmaceutical ingredient (API). During literature search only a few publications were found about nepafenac. HPLC UV methods were mainly presented in patent documents about nepafenac synthesis and chemical purity. The presented method allows to separate all potential related compounds from nepafenac and to quantitate the nepafenac amount. As there is no official monograph in the pharmacopeias about nepafenac, the performed full validation procedure makes the method ready to use in routine analysis. The composition of the mobile phase (10mM ammonium formate, pH 4.1) and the HPLC column (Phenomenex Gemini-NX C18) were selected during the development step. Presented data confirm the benefits of the developed method. Four of the most potential impurities were validated as for the quantitative test and the rest of impurities were validated as for the limit test - according to ICH Q2(R1). The accuracy/recovery results for the chemical purity method are within 90-108%, in the case of assay studies from 99% to 101%; the limit of detection is as low as 15-30ng/mL. The linearity passes all statistical tests. PMID:24406462

Lipiec-Abramska, El?bieta; Jedynak, ?ukasz; Formela, Adam; Roszczy?ski, Jacek; Cybulski, Marcin; Puchalska, Maria; Zagrodzka, Joanna

2014-03-01

138

Protonation/deprotonation process of Emodin in aqueous solution and pKa determination: UV/Visible spectrophotometric titration and quantum/molecular mechanics calculations  

NASA Astrophysics Data System (ADS)

We combined theoretical and experimental studies to elucidate the important deprotonation process of Emodin in water. We used the UV/Visible spectrophotometric titration curves to obtain its pKa values, pKa1 = 8.0 ± 0.1 and pKa2 = 10.9 ± 0.2. Additionally, we obtained the pKa values of Emodin in the water-methanol mixture (1:3v/v). We give a new interpretation of the experimental data, obtaining apparent pKa1 = 6.2 ± 0.1, pKa2 = 8.3 ± 0.1 and pKa3 > 12.7. Performing quantum mechanics calculations for all possible deprotonation sites and tautomeric isomers of Emodin in vacuum and in water, we identified the sites of the first and second deprotonation. We calculated the standard deprotonation free energy of Emodin in water and the pKa1, using an explicit model of the solvent, with Free Energy Perturbation theory in Monte Carlo simulations obtaining, ?Gaq = 12.1 ± 1.4 kcal/mol and pKa1 = 8.7 ± 0.9. With the polarizable continuum model for the solvent, we obtained ?Gaq = 11.6 ± 1.0 kcal/mol and pKa1 = 8.3 ± 0.7. Both solvent models gave theoretical results in very good agreement with the experimental values.

da Cunha, Antonio R.; Duarte, Evandro L.; Lamy, M. Teresa; Coutinho, Kaline

2014-08-01

139

Simultaneous determination of Cinnarizine and Domperidone by area under curve and dual wavelength spectrophotometric methods  

NASA Astrophysics Data System (ADS)

Accurate, selective and sensitive spectrophotometric methods have been developed and validated for simultaneous determination of Cinnarizine and Domperidone, a binary mixture with overlapping spectra, without preliminary separation. These methods include area under the curve (AUC) and dual wavelength spectrophotometry. For the AUC method, the area under curve of mixture solutions in the wavelength ranges 241-258 nm and 280-292 nm were selected for determination of Cinnarizine and Domperidone and by applying Cramer's rule, concentration of each drug was obtained. In dual wavelength method, two wavelengths were selected for each drug in a way so that the difference in absorbance is zero for another drug. Domperidone shows equal absorbance at 240.2 nm and 273.2 nm, where the differences in absorbance were measured for the determination of Cinnarizine. Similarly, differences in absorbance at 230.8 nm and 259.2 nm were measured for determination of Domperidone. The proposed methods were applied for determination of Cinnarizine and Domperidone over the concentration ranges of 2-20 and 2-22 ?g mL-1, respectively. The suggested methods were validated as per USP guidelines and the results revealed that they are reliable, reproducible and precise for routine use with short analysis time. The results obtained by the proposed methods were statistically compared to the reported method, and there was no significant difference between them regarding both accuracy and precision.

Abdelrahman, Maha M.

2013-09-01

140

Optimization and validation of spectrophotometric methods for determination of finasteride in dosage and biological forms  

PubMed Central

Aim and Background: Three simple, accurate and sensitive spectrophotometric methods for the determination of finasteride in pure, dosage and biological forms, and in the presence of its oxidative degradates were developed. Materials and Methods: These methods are indirect, involve the addition of excess oxidant potassium permanganate for method A; cerric sulfate [Ce(SO4)2] for methods B; and N-bromosuccinimide (NBS) for method C of known concentration in acid medium to finasteride, and the determination of the unreacted oxidant by measurement of the decrease in absorbance of methylene blue for method A, chromotrope 2R for method B, and amaranth for method C at a suitable maximum wavelength, ?max: 663, 528, and 520 nm, for the three methods, respectively. The reaction conditions for each method were optimized. Results: Regression analysis of the Beer plots showed good correlation in the concentration ranges of 0.12–3.84 ?g mL–1 for method A, and 0.12–3.28 ?g mL–1 for method B and 0.14 – 3.56 ?g mL–1 for method C. The apparent molar absorptivity, Sandell sensitivity, detection and quantification limits were evaluated. The stoichiometric ratio between the finasteride and the oxidant was estimated. The validity of the proposed methods was tested by analyzing dosage forms and biological samples containing finasteride with relative standard deviation ? 0.95. Conclusion: The proposed methods could successfully determine the studied drug with varying excess of its oxidative degradation products, with recovery between 99.0 and 101.4, 99.2 and 101.6, and 99.6 and 101.0% for methods A, B, and C, respectively. PMID:23781478

Amin, Alaa S.; Kassem, Mohammed A.

2012-01-01

141

Comparative study of novel spectrophotometric methods manipulating ratio spectra: An application on pharmaceutical ternary mixture of omeprazole, tinidazole and clarithromycin  

NASA Astrophysics Data System (ADS)

Three simple, specific, accurate and precise spectrophotometric methods manipulating ratio spectra are developed for simultaneous determination of omeprazole (OM), tinidazole (TN) and clarithromycin (CL) in tablets. Method A, is an extended ratio subtraction one (EXRSM). Method B is a ratio difference spectrophotometric one (RDSM), while method C is mean centering of ratio spectra (MCR). The calibration curves are linear over the concentration range of 1-20 ?g/mL, 10-60 ?g/mL and 0.25-1.0 mg/mL for OM, TN and CL, respectively. The specificity of the developed methods is investigated by analyzing laboratory prepared mixtures of the three drugs and their combined dosage form. Standard deviation values are less than 1.5 in the assay of raw materials and tablets. The three methods are validated as per ICH guidelines and accuracy, precision, repeatability and robustness are found to be within the acceptable limits.

Lotfy, Hayam Mahmoud; Abdel-Monem Hagazy, Maha

2012-10-01

142

Stability-indicating spectrophotometric methods for determination of tazarotene in the presence of its alkaline degradation product by derivative spectrophotometric techniques.  

PubMed

The stability of tazarotene (TZ) was investigated and two stability-indicating methods-namely, first derivative and a derivative ratio spectrophotometric method-were used to determine tazarotene in the presence of its alkaline degradation product (HD) using methanol as a solvent. A linear relationship was obtained in the range 1-10 µg ml?¹ for both methods. By applying the proposed methods, it was possible to determine tazarotene in its pure powdered from with accuracy 99.35 ± 1.410 (n = 10) for the first derivative method and 99.45 ± 1.053 (n = 10) for the derivative ratio method. First derivative and derivative ratio methods were used for the analysis of laboratory-prepared mixtures containing different ratios of tazarotene and its degradation product and they were valid in the presence of up to 70% and 80% degradation product, respectively. The proposed methods were validated and found to be suitable as stability-indicating assay methods for tazarotene in pharmaceutical formulations. PMID:20878894

Badawy, Amr M; El-Alim, Abd El-Aziz B Abd; Saad, Ahmed S

2010-03-01

143

Spectrophotometric methods manipulating ratio spectra for simultaneous determination of binary mixtures with sever overlapping spectra: A comparative study  

NASA Astrophysics Data System (ADS)

Three simple, specific and accurate spectrophotometric methods manipulating ratio spectra were developed and validated for simultaneous determination of Rabeprazole sodium (RB) and Domperidone (DP) in their binary mixture without prior separation. Method A, is constant center spectrophotometric method (CC). Method B is a ratio difference spectrophotometric one (RD), while method C is a combined ratio isoabsorptive point-ratio difference method (RIRD). Linear correlations were obtained in range of 4-44 ?g/mL for both Rabeprazole sodium and Domperidone. The mean percentage recoveries of RB were 99.69 ± 0.504 for method A, 99.83 ± 0.483 for (B) and 100.31 ± 0.499 for (C), respectively, and that of DP were 99.52 ± 0.474 for method A, 100.12 ± 0.505 for (B) and 100.16 ± 0.498 for (C), respectively. Specificity was investigated by analysis of laboratory prepared mixtures containing the cited drugs and their combined tablet dosage form. The obtained results were statistically compared with those obtained by the reported methods, showing no significant difference with respect to accuracy and precision. The three methods were validated as per ICH guidelines and can be applied for routine analysis in quality control laboratories.

Moustafa, H.; Fayez, Y.

2014-12-01

144

Spectrophotometric methods manipulating ratio spectra for simultaneous determination of binary mixtures with sever overlapping spectra: a comparative study.  

PubMed

Three simple, specific and accurate spectrophotometric methods manipulating ratio spectra were developed and validated for simultaneous determination of Rabeprazole sodium (RB) and Domperidone (DP) in their binary mixture without prior separation. Method A, is constant center spectrophotometric method (CC). Method B is a ratio difference spectrophotometric one (RD), while method C is a combined ratio isoabsorptive point-ratio difference method (RIRD). Linear correlations were obtained in range of 4-44?g/mL for both Rabeprazole sodium and Domperidone. The mean percentage recoveries of RB were 99.69±0.504 for method A, 99.83±0.483 for (B) and 100.31±0.499 for (C), respectively, and that of DP were 99.52±0.474 for method A, 100.12±0.505 for (B) and 100.16±0.498 for (C), respectively. Specificity was investigated by analysis of laboratory prepared mixtures containing the cited drugs and their combined tablet dosage form. The obtained results were statistically compared with those obtained by the reported methods, showing no significant difference with respect to accuracy and precision. The three methods were validated as per ICH guidelines and can be applied for routine analysis in quality control laboratories. PMID:24998682

Moustafa, H; Fayez, Y

2014-12-10

145

Selective and validated spectrophotometric methods for the determination of nicorandil in pharmaceutical formulations.  

PubMed

Two simple and sensitive validated spectrophotometric methods have been described for the assay of nicorandil in drug formulations. Method A is based on the reaction of the drug with phloroglucinol-sulfanilic acid reagent in sulfuric acid medium to give yellow-colored product, which absorbs maximally at 425 nm. Method B uses the oxidative coupling of 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) with DL- 3,4 - dihydroxyphenylalanine (DL-dopa) in the presence of nicorandil as oxidant in sulfuric acid medium to form an intensely colored product having maximum absorbance at 530 nm. Beer's law is obeyed in the concentration range 2.5 to 50.0 and 1.0 to 15.0 microg mL(-1) with methods A and B, respectively. Both methods have been successfully applied for the analysis of drug in pharmaceutical formulations. The reliability and the performance of the proposed methods are established by point and interval hypothesis and through recovery studies. The experimental true bias of all samples is smaller than +/-2%. PMID:15760099

Rahman, Nafisur; Ahmad, Yasmin; Azmi, Syed Najmul Hejaz

2004-01-01

146

Optimized and validated spectrophotometric methods for the determination of nicorandil in drug formulations and biological fluids.  

PubMed

Two simple, sensitive and economical spectrophotometric methods have been developed for the determination of nicorandil in drug formulations and biological fluids. Method A is based on the reaction of the drug with brucine-sulphanilic acid reagent in sulphuric acid medium producing a yellow-coloured product, which absorbs maximally at 410 nm. Method B depends on the formation of the intensely blue-coloured product which results due to the interaction of an electrophilic intermediate of 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) with oxidized product of 4-(methyl amino) phenol sulphate (metol) in the presence of nicorandil as an oxidizing agent in sulphuric acid medium. The coloured product shows absorbance maximum at 560 nm. Under the optimized experimental conditions, Beer's law is obeyed in the concentration range of 2.5-35.0 and 0.40-2.2 microg ml(-1) for Methods A and B, respectively. Both the methods have been successfully applied to the determination of nicorandil in drug formulations and biological fluids. The results are validated statistically and through recovery studies. In order to establish the bias and the performance of the proposed methods, the point and interval hypothesis tests have been performed. The experimental true bias of all samples is smaller than +/-2%. PMID:15231427

Rahman, Nafisur; Ahmad Khan, Nadeem; Hejaz Azmi, Syed Najmul

2004-07-01

147

Spectrophotometric method for quantitative determination of iron (III) from iron polymaltose complex in pharmaceutical formulations.  

PubMed

A visible spectrophotometric method has been developed for the quantification of iron (III) from iron polymaltose complex in pure and in pharmaceutical preparations. The method is based on hydrolysis of iron polymaltose complex under acidic conditions and the formation of red colored chromogen with ammonium thiocyanate, which showed absorption peak at 471 nm. This absorption wavelength can be used for the determination of iron (III) from iron polymaltose complex. The limit of detection of iron polymaltose complex at 476 nm was 6.207 ng mL(-1). The calibration was linear in the range of 19.8-22.2 microg mL(-1). Analytical parameters such as stability, selectivity, accuracy and precision have been established for the method in HAEMOTYL syrup and evaluated statistically to assess the application of the method. The method was validated under the ICH and USP guidelines and found to comprise the advantages for simplicity, stability, sensitivity, reproducibility and accuracy for using as a method for the routine analysis of the drug in pharmaceutical formulations and in pharmaceutical investigations involving iron polymaltose complex. PMID:17105708

Hussain, Fida; Arayne, M Saeed; Sultana, Najma

2006-10-01

148

A Laboratory calibration transfer method for broadband UV filter radiometers  

NASA Astrophysics Data System (ADS)

As a consequence of stratospheric ozone depletion and due to the current uncertainties in the Earth's climate, ultraviolet radiation observations become increasingly important and nowadays form a part of many radiation monitoring networks. UV irradiance is commonly measured either with spectrophotometers or with broadband (or wide-band) filter radiometers (UV-A, UV-B and Erythemal weighting). Due to the physical limitations of filter materials and detectors, the spectral response functions of broadband UV radiometers are not identical to theoretical spectral sensitivities. Such a spectral mismatch introduces discrepancies between measured and real UV radiative quantities. If the spectral mismatch of the radiometers and the calibration measurement conditions are accounted for in the calibration procedure the measurement accuracy is considerably increased. A widely used practice to realize this improvement is to use the sun as a light source and to take collocated and synchronized UV measurements, obtained with a spectroradiometer and the broadband filter radiometers. However, at higher latitudes calibration is impossible during the winter season due to the low UV intensity. Therefore, a method is developed to transfer the outdoor calibrations of several reference instruments in the laboratory to other instruments by means of a well-maintained monochromator system with an absolute calibrated photodiode detector. The paper gives a summary of the new laboratory transfer method and discusses the results of a small intercomparison between measurements obtained from the laboratory transfer method and the measurements obtained from the outdoor calibration method.

Los, A.

2003-04-01

149

Validation of spectrophotometric method for Se(IV) determination: analytical applications.  

PubMed

As selenium is an important part of the antioxidant enzymes and also because there are several studies suggesting a possible link between cancer and selenium deficiency, this paper presents a spectrophotometric method for the assay of Se(IV), using N,N-diethyl-p-phenylenediamine monohydrochloride as reagent. The proposed method is based on the reaction between the selenium and potassium iodide in low acidic medium, when iodine is released. This last product will further oxidise the new reagent. The final obtained product is strongly coloured in red and has an absorption maximum at 552 nm and molar extinction coefficient (?) of 6.1 × 10(4) L mol(-1) cm(-1). The optimum working conditions were established, and the developed method was validated, being characterised by a good linearity (in the range of 0.5-3.0 ?g/mL), a limit of detection (0.0573 ?g/mL) and a limit of quantification (0.1737 ?g/mL). At the same time, the repeatability, the precision of the method and the accuracy were established. The proposed and validated method was applied with good results for the determination of Se(IV) in spring and bottled water from Iasi and also in pharmaceutical and cosmetic products. PMID:24488364

Tantaru, Gladiola; Vieriu, Madalina; Popescu, Maria-Cristina

2014-05-01

150

A new, sensitive, and rapid spectrophotometric method for the determination of sulfa drugs.  

PubMed

A sensitive, rapid, and simple spectrophotometric method is described for the determination of sulfa drugs. The method is based on the formation of a red-colored product by the diazotization of sulfonamides such as sulfathiazole (SFT), sulfadiazine (SFD), sulfacetamide (SFA), sulfamethoxazole (SFMx), sulfamerazine (SFMr), sulfaguanidine (SFG), and sulfamethazine (SFMt), followed by complexation with dopamine in the presence of molybdate ions in (1 + 1) H2SO4 medium. Absorbance of the resulting red product is measured at 490-510 nm, and the product is stable for 2 days at 27 degrees C. Beer's law is obeyed in the concentration range of 0.04-8.0 microg/mL at the wavelength of maximum absorption. The method was used successfully for the determination of some sulfonamides in tablets and eye drops. Common excipients used as additives in pharmaceuticals do not interfere in the proposed method. The method offers the advantages of simplicity, rapidity, and sensitivity without the need for extraction or heating. The limits of detection and quantitation were calculated for SFT, SFD, SFA, SFMx, SFMr, SFG, and SFMt. PMID:12180680

Nagaraja, Padmarajaiah; Yathirajan, Hemmige S; Sunitha, Kallanchira R; Vasantha, Ramanathapura A

2002-01-01

151

A Spectrophotometric Method to Determine the Inclination of Class I Objects  

E-print Network

A new method which enables us to estimate the inclination of Class I young stellar objects is proposed. Since Class I objects are not spherically symmetric, it is likely that the observed feature is sensitive to the inclination of the system. Thus, we construct a protostar model by carefully treating two-dimensional (2D) radiative transfer and radiative equilibrium. We show from the present 2D numerical simulations that the emergent luminosity L_SED,which is the frequency integration of spectral energy distribution (SED), depends strongly on the inclination of the system i, whereas the peak flux is insensitive to i. Based on this result, we introduce a novel indicator f_L, which is the ratio of L_SED to the peak flux, as a good measure for the inclination. By using f_L, we can determine the inclination regardless of the other physical parameters. The inclination would be determined by f_L within the accuracy of +- 5 degree, if the opening angle of bipolar outflows is specified by any other procedure. Since this spectrophotometric method is easier than a geometrical method or a full SED fitting method, this method could be a powerful tool to investigate the feature of protostars statistically with observational data which will be provided by future missions, such as SIRTF, ASTRO-F, and ALMA.

T. Nakazato; T. Nakamoto; M. Umemura

2002-10-11

152

Novel Spectrophotometric Method for the Determination of Pindolol in Pharmaceutical Samples  

NASA Astrophysics Data System (ADS)

A new facile and sensitive spectrophotometric determination of Pindolol (PDL), a beta blocker drug has been developed and validated. The method was based on the reaction between pindolol and K3 [Fe(CN)6] in presence of FeCl3 to form Prussian blue. The absorbance values were recorded at 700 nm and a calibrated graph was constructed. A dynamic Beer's law range was observed in the range 0.125-2.5 ?g mL-1 with a detection limit of 0.03 ?g mL-1 and a quantitation limit of 0.08 ?g mL-1. Various experimental parameters such as effect of solvents, stability, interference effects due to excipients etc were studied. The reproducibility of this methods were checked by six replicate determinations at 1.0 ?g ml-1 PDL and the standard deviation was found to be between 0.20 and 0.42%. The results were statistically compared with those of the reference/literature method by applying Student's t-test and F-test. The sensitivity, simplicity, temperature independence and stability of the colored product are the advantages of the proposed method and it is also free from extraction steps and use of carcinogenic solvents.

Nagaraja, P.; Kumar, H. R. Arun; Bhaskara, B. L.; Kumar, S. Anil

2011-10-01

153

An automated sequential injection spectrophotometric method for evaluation of tyramine oxidase inhibitory activity of some flavonoids.  

PubMed

An automated sequential injection (SI) spectrophotometric system has been developed for evaluation of tyramine oxidase (TOD) inhibitory activity. The method is based on the inhibition of TOD that catalyzes the oxidation of tyramine substrate to produce aldehyde and hydrogen peroxide (H?O?). The produced H?O? reacts with vanillic acid and 4-aminoantipyrine (4-AA) in the presence of peroxidase (POD) to form a quinoneimine dye, the absorbance of which is measured of absorbance at wavelength of 490 nm. The decrease of the quinoneimine dye is related to an increase of TOD inhibitory activity. Under the optimum conditions: 1.0 mM tyramine, 8 U mL(-1) TOD, 1.0 mM vanillic acid, 1.0 mM 4-AA and delay time of 10 s, some flavonoid compounds were examined for the TOD inhibitory activity expressed as IC?? value. It was found that flavonols (quercetin and myricetin) and flavans (epicatechin gallate (ECG) and epigallocatechin (EGC)) showed higher TOD inhibitory activity than flavones and flavanones. The results of IC?? values obtained from the proposed method and a batch-wise method were not significantly different from each other. Moreover, the SI system enabled automation of the analysis, leading to more convenient, more sensitive and faster analysis than the batch-wise method. A precise timing of the system also improves precision and accuracy of the assay, especially when the measurement of absorbance at non-steady state condition is involved. PMID:24720993

Moonrungsee, Nuntaporn; Shimamura, Tomoko; Kashiwagi, Takehiro; Jakmunee, Jaroon; Higuchi, Keiro; Ukeda, Hiroyuki

2014-05-01

154

Spectrophotometric method for the determination of Gemifloxacin mesylate in pure and tablet dosage form.  

PubMed

A spectrophotometric method for the determination of Gemifloxacin mesylate (GFX) is developed and validated according to ICH guidelines. GFX is a fluoroquinolone that is used in the treatment of pneumonia. The analysis of the pure drug was carried out at its ?max 270 nm. The method was linear from 0.5-5?g/mL, r(2) 0.999 and equation is 0.102-0.000. The % RSD for inter-day (0.969%) and intra-day (0.714%) assuring a good precision and accuracy was close to 100%. Limit of detection and Limit of quantification were 0.197 and 0.599?g/mL, respectively. The validation results and statistical data demonstrate that the method is accurate, sensitive, cost effective and reproducible and has an importance in quality assurance of GFX analysis. The developed method was proved suitable for analysis of GFX in the pure and tablet dosage forms without interference of excepients. PMID:25176374

Hassan, Syed Saeedul; Hayat, Uzma; Tariq, Imran; Ahmad, Irshad; Hayat, Muhammad Munawar; Uzair, Muhammad; Ansari, Muhammad Tayyab

2014-09-01

155

Development and validation of sensitive spectrophotometric method for determination of two antiepileptics in pharmaceutical formulations.  

PubMed

Rapid, sensitive and validated spectrophotometric methods for the determination of two antiepileptics (gabapentin (GAB) and pregabalin (PRG)) in pure forms and in pharmaceutical formulations was developed. The method is based on the formation of charge transfer complex between drug and the chromogenic reagents quinalizarin (Quinz) and alizarin red S (ARS) producing charge transfer complexes in methanolic medium which showed an absorption maximum at 571 and 528 nm for GAB and 572 and 538 nm for PRG using Quinz and ARS, respectively. The optimization of the reaction conditions such as the type of solvent, reagent concentration and reaction time were investigated. Beer's law is obeyed in the concentration ranges 0.4-8.0 and 0.5-10 ?g mL(-1) for GAB and PRG using Quinz and ARS, respectively. The molar absorptivity, Sandell sensitivity, detection and quantification limits are also calculated. The correlation coefficients were ?0.9992 with a relative standard deviation (RSD%) of ?1.76. The methods are successfully applied to the determination of GAB and PRG in pharmaceutical formulations and the validity assesses by applying the standard addition technique, which compared with those obtained using the reported methods. PMID:23352920

Gouda, Ayman A; Malah, Zakia Al

2013-03-15

156

A simple spectrophotometric method for the determination of beta-blockers in dosage forms.  

PubMed

A simple, extraction-free spectrophotometric method is proposed for the analysis of some beta-blockers, namely atenolol, timolol and nadolol. The method is based on the interaction of the drugs in chloroform with 0.1% chloroformic solutions of acidic sulphophthalein dyes to form stable, yellow-coloured, ion-pair complexes peaking at 415 nm. The dyes used were bromophenol blue (BPB), bromothymol blue (BTB) and bromocresol purple (BCP). Under the optimum conditions, the three drugs could be assayed in the concentration range 1-10 microg ml(-1) with correlation coefficient (n = 5) more than 0.999 in all cases. The stoichiometry of the reaction was found to be 1:1 in all cases and the conditional stability constant (K(F)) of the complexes have been calculated. The free energy changes (DeltaG) were determined for all complexes formed. The interference likely to be introduced from co-formulated drugs was studied and their tolerance limits were determined. The proposed method was then applied to dosage-forms the percentage recoveries ranges from 99.12-100.95, and the results obtained were compared favorably with those given with the official methods. PMID:16111848

Al-Ghannam, S M

2006-01-23

157

Pregabalin and Tranexamic Acid Evaluation by Two Simple and Sensitive Spectrophotometric Methods  

PubMed Central

This paper demonstrates colorimetric visible spectrophotometric quantification methods for amino acid, namely, tranexamic acid and pregabalin. Both drugs contain the amino group, and when they are reacted with 2,4-dinitrophenol and 2,4,6-trinitrophenol, they give rise to yellow colored complexes showing absorption maximum at 418?nm and 425?nm, respectively, based on the Lewis acid base reaction. Detailed optimization process and stoichiometric studies were conducted along with investigation of thermodynamic features, that is, association constant and standard free energy changes. The method was linear over the concentration range of 0.02–200?µgmL?1 with correlation coefficient of more than 0.9990 in all of the cases. Limit of detection was in range from 0.0041 to 0.0094?µgmL?1 and limit of quantification was in the range from 0.0137 to 0.0302?µgmL?1. Excellent recovery in Placebo spiked samples indicated that there is no interference from common excipients. The analytical methods under proposal were successfully applied to determine tranexamic acid and pregabalin in commercial products. t-test and F ratio were evaluated without noticeable difference between the proposed and reference methods. PMID:25873964

Sher, Nawab; Fatima, Nasreen; Perveen, Shahnaz; Siddiqui, Farhan Ahmed; Wafa Sial, Alisha

2015-01-01

158

Development and validation of sensitive spectrophotometric method for determination of two antiepileptics in pharmaceutical formulations  

NASA Astrophysics Data System (ADS)

Rapid, sensitive and validated spectrophotometric methods for the determination of two antiepileptics (gabapentin (GAB) and pregabalin (PRG)) in pure forms and in pharmaceutical formulations was developed. The method is based on the formation of charge transfer complex between drug and the chromogenic reagents quinalizarin (Quinz) and alizarin red S (ARS) producing charge transfer complexes in methanolic medium which showed an absorption maximum at 571 and 528 nm for GAB and 572 and 538 nm for PRG using Quinz and ARS, respectively. The optimization of the reaction conditions such as the type of solvent, reagent concentration and reaction time were investigated. Beer's law is obeyed in the concentration ranges 0.4-8.0 and 0.5-10 ?g mL-1 for GAB and PRG using Quinz and ARS, respectively. The molar absorptivity, Sandell sensitivity, detection and quantification limits are also calculated. The correlation coefficients were ?0.9992 with a relative standard deviation (RSD%) of ?1.76. The methods are successfully applied to the determination of GAB and PRG in pharmaceutical formulations and the validity assesses by applying the standard addition technique, which compared with those obtained using the reported methods.

Gouda, Ayman A.; Malah, Zakia Al

2013-03-01

159

Simultaneous determination of caffeine, theophylline and theobromine in food samples by a kinetic spectrophotometric method.  

PubMed

A novel kinetic spectrophotometric method was developed for the simultaneous determination of caffeine, theobromine and theophylline in food samples. This method was based on the different kinetic characteristics between the reactions of analytes with cerium sulphate in sulphuric acid and the associated change in absorbance at 320 nm. Experimental conditions, the effects of sulphuric acid, cerium sulphate and temperature, were optimised. Linear ranges (0.4-8.4 ?g mL(-1)) for all three analytes were established, and the limits of detection were: 0.30 ?g mL(-1) (caffeine), 0.33 ?g mL(-1) (theobromine) and 0.16 ?g mL(-1) (theophylline). The recorded data were processed by partial least squares and artificial neural network, and the developed mathematical models were then used for prediction. The proposed, novel method was applied to determine the analytes in commercial food samples, and there were no significant differences between the results from the proposed method and those obtained by high-performance liquid chromatography. PMID:23993589

Xia, Zhenzhen; Ni, Yongnian; Kokot, Serge

2013-12-15

160

DETERMINATION OF BENZOIC ACID AND SALICYLIC ACID IN COMMERCIAL BENZOIC AND SALICYLIC ACIDS OINTMENTS BY SPECTROPHOTOMETRIC METHOD  

Microsoft Academic Search

Commercial benzoic acid and salicylic acid ointments have been analyzed for benzoic acid and salicylic acid content by using a spectrophotometric method. Since benzoic acid and salicylic acid exhibit overlapping spectra, absorbance measurements are made at two wavelengths, i.e. 271 nm and 303 nm in ethanol (96%v\\/v) for simultaneous determination of the two compounds. The method is direct and involves

IQBAL AHMAD; FAIYAZ HM VAID

161

NEW SPECTROPHOTOMETRIC METHOD FOR THE DETERMINATION OF FLUTAMIDE IN PHARMACEUTICAL PREPARATION USING CHROMOTROPIC ACID AS A COUPLING AGENT  

Microsoft Academic Search

A rapid, selective, sensitive spectrophotometric method for the determination of flutamide (FLA) is described by the interaction of reduced flutamide in presence of potassium ferricyanide (K3(Fe(CN)6)) with chromotropic acid in basic medium. Absorbance of the resulting chromophore is measured at 465 nm and is stable for more than 7 days. The method is successfully employed for the determination of flutamide

K. M. Reddy; K. Suvardhan; K. Suresh; S. Prabhakar; P. Chiranjeevi

162

A novel approach in dispersive liquid-liquid microextraction based on the use of an auxiliary solvent for adjustment of density UV-VIS spectrophotometric and graphite furnace atomic absorption spectrometric determination of gold based on ion pair formation.  

PubMed

This paper presents a novel approach to dispersive liquid-liquid microextraction (DLLME), based on the use of an auxiliary solvent for the adjustment of density. The procedure utilises a solvent system consisting of a dispersive solvent, an extraction solvent and an auxiliary solvent, which allows for the use of solvents having a density lower than that of water as an extraction solvent while preserving simple phase separation by centrifugation. The suggested approach could be an alternative to procedures described in the literature in recent months and which have been devoted to solving the same problem. The efficiency of the suggested approach is demonstrated through the determination of gold based on the formation of the ion pair [Au(CN)(2)](-) anion with Astra Phloxine (R) reagent and its extraction using the DLLME procedure with subsequent UV-VIS spectrophotometric and graphite furnace atomic absorption spectrometric detection. The optimum conditions were found to be: pH 3; 0.8 mmol L(-1) K(4)[Fe(CN)(6)]; 0.12 mmol L(-1) R; dispersive solvent, methanol; extraction solvent, toluene; auxiliary solvent, tetrachloromethane. The calibration plots were linear in the ranges 0.39-4.7 mg L(-1) and 0.5-39.4 ?g L(-1) for UV-VIS and GFAAS detection, respectively; thus enables the application of the developed method in two ranges differing from one from another by three orders of magnitude. The presented approach can be applied to the development of DLLME procedures for the determination of other compounds extractable by organic solvents with a density lower than that of water. PMID:20875602

Kocúrová, Lívia; Balogh, Ioseph S; Skrlíková, Jana; Posta, József; Andruch, Vasil

2010-10-15

163

Simple, rapid, and highly sensitive detection of diphosgene and triphosgene by spectrophotometric methods  

Microsoft Academic Search

Methods for the detection and estimation of diphosgene and triphosgene are described. These compounds are widely used phosgene precursors which produce an intensely colored purple pentamethine oxonol dye when reacted with 1,3-dimethylbarbituric acid (DBA) and pyridine (or a pyridine derivative). Two quantitative methods are described, based on either UV absorbance or fluorescence of the oxonol dye. Detection limits are ?4?mol\\/L

Abraham Joy; Emmanuel Anim-Danso; Joachim Kohn

2009-01-01

164

A rapid derivative spectrophotometric method for simultaneous determination of naphazoline and antazoline in eye drops.  

PubMed

A zero-crossing first-derivative spectrophotometric method is applied for the simultaneous determination of naphazoline hydrochloride and antazoline phosphate in eye drops. The measurements were carried out at wavelengths of 225 and 252 nm for naphazoline hydrochloride and antazoline phosphate, respectively. The method was found to be linear (r2>0.999) in the range of 0.2-1 microg/ml for naphazoline hydrochloride in the presence of 5 microg/ml antazoline phosphate at 225 nm. The same linear correlation (r2>0.999) was obtained in the range of 1-10 microg/ml of antazoline phosphate in the presence of 0.5 microg/ml of naphazoline hydrochloride at 252 nm. The limit of determination was 0.2 microg/ml and 1 microg/ml for naphazoline hydrochloride and antazoline phosphate, respectively. The method was successfully used for simultaneous analysis of naphazoline hydrochloride and antazoline phosphate in eye drops without any interference from excipients and prior separation before analysis. PMID:16394564

Souri, Effat; Amanlou, Massoud; Farsam, Hassan; Afshari, Alma

2006-01-01

165

Sensitive extractive spectrophotometric methods for the determination of trazodone hydrochloride in pharmaceutical formulations.  

PubMed

Two simple, rapid and sensitive extractive spectrophotometric methods have been developed for the assay of trazodone hydrochloride (TRH) in pure and pharmaceutical formulations. These methods are based on the formation of chloroform soluble ion-association complexes of TRH with bromothymol blue (BTB) and with bromocresol purple (BCP) in KCl-HCl buffer of pH 2.0 (for BTB) and in NaOAc-AcOH buffer of pH of 3.6 (for BCP) with absorption maximum at 423 nm and at 408 nm for BTB and BCP, respectively. Reaction conditions were optimized to obtain the maximum color intensity. The absorbance was found to increase linearly with increase in concentration of TRH, which was corroborated by the calculated correlation coefficient values (0.9996, 0.9945). The systems obeyed Beer's law in the range of 0.2-14.5 and 0.2-14.1 microg/ml for BTB and BCP, respectively. Various analytical parameters have been evaluated and the results have been validated by statistical data. No interference was observed from common excipients present in pharmaceutical formulations. The proposed methods are simple, accurate and suitable for quality control applications. PMID:16819213

Sudhir Kumar, Ramanaboyina; Manjunatha, Devagondanahalli Hadagali; Shaikh, Sarfaraj Mohd Takhi; Seetharamappa, Jaldappa; Harikrishna, Kasalanti

2006-07-01

166

A Highly Sensitive Kinetic Spectrophotometric Method for the Determination of Ascorbic Acid in Pharmaceutical Samples  

PubMed Central

In this study, a new reaction system for quantitative determination of ascorbic acid was introduced. The developed method is based on inhibitory effect of ascorbic acid on the Orange G-bromate system. The change in absorbance was followed spectrophotometrically at 478 nm. The dependence of sensitivity on the reaction variables including reagents concentration, temperature and time was investigated. Under optimum experimental conditions, calibration curve was linear over the range 0.7 – 33.5 ?g mL-1 of ascorbic acid including two linear segments and the relative standard deviations (n = 6) for 5.0 and 20.0 ?g mL–1 of ascorbic acid were 1.08 and 1.02%, respectively. The limit of detection was 0.21 ?g mL?1 of ascorbic acid. The effect of diverse species was also investigated. The developed method was successfully applied for the determination of ascorbic acid in pharmaceutical samples. The results were in a good agreement with those of reference method. PMID:25237333

Shishehbore, Masoud Reza; Aghamiri, Zahra

2014-01-01

167

A New Technique for Quantitative Determination of Dexamethasone in Pharmaceutical and Biological Samples Using Kinetic Spectrophotometric Method  

PubMed Central

Dexamethasone is a type of steroidal medications that is prescribed in many cases. In this study, a new reaction system using kinetic spectrophotometric method for quantitative determination of dexamethasone is proposed. The method is based on the catalytic effect of dexamethasone on the oxidation of Orange G by bromate in acidic media. The change in absorbance as a criterion of the oxidation reaction progress was followed spectrophotometrically. To obtain the maximum sensitivity, the effective reaction variables were optimized. Under optimized experimental conditions, calibration graph was linear over the range 0.2–54.0?mg?L?1. The calculated detection limit (3sb/m) was 0.14?mg?L?1 for six replicate determinations of blank signal. The interfering effect of various species was also investigated. The present method was successfully applied for the determination of dexamethasone in pharmaceutical and biological samples satisfactorily. PMID:25737724

Akhoundi-Khalafi, Ali Mohammad; Shishehbore, Masoud Reza

2015-01-01

168

Determination of lead and cadmium in soils, sludges, and fertilizers by an ion-exchange/spectrophotometric method  

SciTech Connect

The MetalTrace method, which consists of an anion-exchange separation coupled with a spectrophotometric quantification, was used to determine lead and cadmium in sulfuric acid-hydrogen peroxide digests of soils and sludges and hydrobromic acid extracts of soils. Cadmium only was determined in sulfuric acid-hydrogen peroxide digests of fertilizers because no standards were available with certified lead contents. The selectivity provided by the anion-exchange separation allowed the use of a spectrophotometric indicator with an extremely high extinction coefficient so that detection limits in the low parts per million range could be attained. The results obtained using this method compared favorably with those obtained using much more expensive methods requiring more specialized training and equipment.

Heinzig, M.; DeYong, G.D.; Anglin, R.J.; Bowden, B.K. [Hach Co., Ames, IA (United States). Hach Ames Chemical Research; Brayton, S.V. [Hach Co., Ames, IA (United States). Hach Corporate Research

1993-12-01

169

A spectrophotometric method for the determination of zinc, copper, and cobalt ions in metalloproteins using Zincon.  

PubMed

Zincon (2-carboxy-2'-hydroxy-5'-sulfoformazylbenzene) has long been known as an excellent colorimetric reagent for the detection of zinc and copper ions in aqueous solution. To extend the chelator's versatility to the quantification of metal ions in metalloproteins, the spectral properties of Zincon and its complexes with Zn(2+), Cu(2+), and Co(2+) were investigated in the presence of guanidine hydrochloride and urea, two common denaturants used to labilize metal ions in proteins. These studies revealed the detection of metals to be generally more sensitive with urea. In addition, pH profiles recorded for these metals indicated the optimal pH for complex formation and stability to be 9.0. As a consequence, an optimized method that allows the facile determination of Zn(2+), Cu(2+), and Co(2+) with detection limits in the high nanomolar range is presented. Furthermore, a simple two-step procedure for the quantification of both Zn(2+) and Cu(2+) within the same sample is described. Using the prototypical Cu(2+)/Zn(2+)-protein superoxide dismutase as an example, the effectiveness of this method of dual metal quantification in metalloproteins is demonstrated. Thus, the spectrophotometric determination of metal ions with Zincon can be exploited as a rapid and inexpensive means of assessing the metal contents of zinc-, copper-, cobalt-, and zinc/copper-containing proteins. PMID:19854146

Säbel, Crystal E; Neureuther, Joseph M; Siemann, Stefan

2010-02-15

170

Investigation on the interaction of Safranin T with anionic polyelectrolytes by spectrophotometric method  

NASA Astrophysics Data System (ADS)

Understanding the role played by chemical additives such as NaCl salt, acid and Cetylpyridinium Chloride (CPC) surfactant on the interaction between dye and polyelectrolyte contributes to optimization of processes using polyelectrolytes in the removal of dye from aqueous solution. Herein we focus in the interaction between Safranin T, a cationic dye, with two anionic polyelectrolytes, poly(ammonium acrylate) and poly(acrylic acid) using spectrophotometric method and conductivity measurement. In aqueous solution, each of anionic polyelectrolytes forms a complex with the dye and induces a metachromasy indicated by the blue shift of the absorbance of the dye. The stoichiometry of complexes evaluated by the molar ratio method are 1:1 for Safranin T poly(ammonium acrylate) and 2:1 in the case of Safranin T poly(acrylic acid). The effect of additives on the stability of complexes has been studied by varying concentrations of the salt and the surfactant and pH of the solution. The thermodynamic parameters of interaction ?G, ?H and ?S at different temperatures were evaluated to determine the stability constant of the complexes.

Fradj, Anouar Ben; Lafi, Ridha; Hamouda, Sofiane Ben; Gzara, Lassaad; Hamzaoui, Ahmed Hichem; Hafiane, Amor

2014-10-01

171

Spectrophotometric method for the determination of total thiols in human urine.  

PubMed

Thiols have been of enduring interest for many years because of their role in biological and pharmacological processes. Monitoring of total thiols content is very important in order to understand their function in living organisms. This paper describes the spectrophotometric method for the determination of total thiols concentration in urine. The method is based on derivatization with 1-benzyl-2-chloropyridinium bromide and ultraviolet detection of S-pyridinium derivatives at 316 nm. The analytical recovery and RSD values for precision within the calibration range were from 95.7 to 102.9% and from 2.1 to 8.4%, respectively. The concentration of total thiols normalized against creatinine for 38 apparently healthy subjects (19 women and 19 men) occurred in the range 17.2-73.7 and 25.7-83.6 mmol/mol creatinine, respectively. There was no difference in the urinary excretion of thiols in men and women, but there was a significant statistical correlation between urine total thiols and age in the studied group. PMID:24247800

Chwatko, Grazyna

2013-01-01

172

A simple and highly sensitive spectrophotometric method for the determination of cyanide in equine blood.  

PubMed

An epidemiological association among black cherry trees (Prunus serotina), eastern tent caterpillars (Malacosoma americana), and the spring 2001 episode of mare reproductive loss syndrome in central Kentucky focused attention on the potential role of environmental cyanogens in the causes of this syndrome. To evaluate the role of cyanide (CN (-)) in this syndrome, a simple, rapid, and highly sensitive method for determination of low parts per billion concentrations of CN (-) in equine blood and other biological fluids was developed. The analytical method is an adaptation of methods commonly in use and involves the evolution and trapping of gaseous hydrogen cyanide followed by spectrophotometric determination by autoanalyzer. The limit of quantitation of this method is 2 ng/mL in equine blood, and the standard curve shows a linear relationship between CN (-) concentration and absorbance (r >. 99). The method throughput is high, up to 100 samples per day. Normal blood CN (-) concentrations in horses at pasture in Kentucky in October 2001 ranged from 3-18 ng/mL, whereas hay-fed horses showed blood CN (-) levels of 2-7 ng/mL in January 2002. Blood samples from a small number of cattle at pasture showed broadly similar blood CN (-) concentrations. Intravenous administration of sodium cyanide and oral administration of mandelonitrile and amygdalin yielded readily detectable increases in blood CN (-) concentrations. This method is sufficiently sensitive and specific to allow the determination of normal blood CN (-) levels in horses, as well as the seasonal and pasture-dependent variations. The method should also be suitable for investigation of the toxicokinetics and disposition of subacutely toxic doses of CN (-) and its precursor cyanogens in the horse as well as in other species. PMID:20021191

Hughes, Charlie; Lehner, Fritz; Dirikolu, Levent; Harkins, Dan; Boyles, Jeff; McDowell, Karen; Tobin, Thomas; Crutchfield, James; Sebastian, Manu; Harrison, Lenn; Baskin, Stephen I

2003-01-01

173

Highly sensitive and selective spectrophotometric and spectrofluorimetric methods for the determination of ropinirole hydrochloride in tablets  

NASA Astrophysics Data System (ADS)

Three sensitive, selective, accurate spectrophotometric and spectrofluorimetric methods have been developed for the determination of ropinirole hydrochloride in tablets. The first method was based on measuring the absorbance of drug solution in methanol at 250 nm. The Beer's law was obeyed in the concentration range 2.5-24 ?g ml -1. The second method was based on the charge transfer reaction of drug, as n-electron donor with 7,7,8,8-tetracyanoquinodimethane (TCNQ), as ?-acceptor in acetonitrile to give radical anions that are measured at 842 nm. The Beer's law was obeyed in the concentration range 0.6-8 ?g ml -1. The third method was based on derivatization reaction with 4-chloro-7-nitrobenzofurazan (NBD-Cl) in borate buffer of pH 8.5 followed by measuring the fluorescence intensity at 525 nm with excitation at 464 nm in chloroform. Beer's law was obeyed in the concentration range 0.01-1.3 ?g ml -1. The derivatization reaction product of drug with NBD-Cl was characterized by IR, 1H NMR and mass spectroscopy. The developed methods were validated. The following analytical parameters were investigated: the molar absorptivity ( ?), limit of detection (LOD, ?g ml -1) and limit of quantitation (LOQ, ?g ml -1), precision, accuracy, recovery, and Sandell's sensitivity. Selectivity was validated by subjecting stock solution of ropinirole to acidic, basic, oxidative, and thermal degradation. No interference was observed from common excipients present in formulations. The proposed methods were successfully applied for determination of drug in tablets. The results of these proposed methods were compared with each other statistically.

Aydo?mu?, Zeynep

2008-06-01

174

Novel spectrophotometric methods for simultaneous determination of Amlodipine, Valsartan and Hydrochlorothiazide in their ternary mixture.  

PubMed

This work represents a comparative study of two smart spectrophotometric techniques namely; successive resolution and progressive resolution for the simultaneous determination of ternary mixtures of Amlodipine (AML), Hydrochlorothiazide (HCT) and Valsartan (VAL) without prior separation steps. These techniques consist of several consecutive steps utilizing zero and/or ratio and/or derivative spectra. By applying successive spectrum subtraction coupled with constant multiplication method, the proposed drugs were obtained in their zero order absorption spectra and determined at their maxima 237.6nm, 270.5nm and 250nm for AML, HCT and VAL, respectively; while by applying successive derivative subtraction they were obtained in their first derivative spectra and determined at P230.8-246, P261.4-278.2, P233.7-246.8 for AML, HCT and VAL respectively. While in the progressive resolution, the concentrations of the components were determined progressively from the same zero order absorption spectrum using absorbance subtraction coupled with absorptivity factor methods or from the same ratio spectrum using only one divisor via amplitude modulation method can be used for the determination of ternary mixtures using only one divisor where the concentrations of the components are determined progressively. The proposed methods were checked using laboratory-prepared mixtures and were successfully applied for the analysis of pharmaceutical formulation containing the cited drugs. Moreover comparative study between spectrum addition technique as a novel enrichment technique and a well established one namely spiking technique was adopted for the analysis of pharmaceutical formulations containing low concentration of AML. The methods were validated as per ICH guidelines where accuracy, precision and specificity were found to be within their acceptable limits. The results obtained from the proposed methods were statistically compared with the reported one where no significant difference was observed. PMID:25638433

Lotfy, Hayam M; Hegazy, Maha A; Mowaka, Shereen; Mohamed, Ekram Hany

2015-04-01

175

Simple and sensitive spectrophotometric method for determination of tricyclic antidepressant imipramine using Fe(III)SCN ? complex  

Microsoft Academic Search

A new simple procedure for the spectrophotometric determination of tricyclic antidepressant drug imipramine is proposed. The\\u000a method is based on the enhancement of the colour intensity of the Fe(III)-SCN? complex due to the addition of the drug imipramine. The value of molar absorptivity of the Fe(III)-SCN? imipramine complex in terms of the drug lies in the range of (2.77–3.16) ×

Pankaj Soni; Santosh K. Sar; Anand Kamavisdar; Rajmani Patel

2011-01-01

176

DETERMINATION OF TRIPROLIDINE-HCl BY SPECTROPHOTOMETRIC METHOD IN PURE AND PHARMACEUTICAL PREPARATIONS USING DICHLORONITROBENZENE AS A NEW CHROMOGENIC REAGENT  

Microsoft Academic Search

In the present study it is demonstrated that H1- blockers such as triprolidine-HCl can be determined by a very simple, sensitive and accurate spectrophotometric procedure. The method consisted of interaction of triprolidine-HCl with dichloronitrobenzene in alkaline medium. Absorbance of resulting orange colour was measured at 440 nm .The reaction turned out to be selective for triprolidine -HCl with 0.005 mgml-1

Amina Mumtaz; Asrar A. Kazi; Tehseen Aman; M. Usman Sabri; Fauzia Noureen

177

Comparative validation of amisulpride determination in pharmaceuticals by several chromatographic, electrophoretic and spectrophotometric methods  

Microsoft Academic Search

Nine accurate methods for determination of amisulpride in tablets: reversed phase high pressure liquid chromatography (RP-HPLC), aqueous capillary electrophoresis (CE), non-aqueous CE, normal phase (NP) and reversed-phase (RP) high performance thin layer chromatography (HPTLC) with densitometry and videodensitometry, and direct and derivative UV spectrophotometry were developed and validated. The HPLC was carried out using Nova-Pak C8 column and mobile phase

Robert Skibi?ski; ?ukasz Komsta; Hanna Hopka?a; Izabela Suchodolska

2007-01-01

178

Flow injection spectrophotometric method for chloride determination in natural waters using Hg(SCN)(2) immobilized in epoxy resin.  

PubMed

A flow injection (FI) spectrophotometric method was proposed for the determination of chloride ion in natural waters. The determination of chloride was carried out by reaction with Hg(SCN)(2) immobilized in an epoxy resin bead in a solid-phase reactor (SPR) and the thiocyanate ions released were determined spectrophotometrically at 480nm after complexing reaction with Fe(III). The analytical curve for chloride was linear in the concentration range from 5.6 x 10(-5) to 2.2 x 10(-4)moll(-1) with a detection limit of 1.4 x 10(-5)moll(-1). The relative standard deviation (R.S.D.) was 2.2% for a solution containing 2.2 x 10(-4)moll(-1) (n = 10). The simple manifold allows a routine analytical frequency of 100 determinations per hour. The main advantage of the developed method is the 400% reduction of the Hg waste solution generated when compared to conventional methods for chloride determination based on the same spectrophotometric reaction. PMID:18969896

Silva, Claudineia R; Vieira, Heberth J; Canaes, Larissa S; Nóbrega, Joaquim A; Fatibello-Filho, Orlando

2005-02-28

179

Spectrophotometric and thermodynamic study on the dimerization equilibrium of ionic dyes in water by chemometrics method  

NASA Astrophysics Data System (ADS)

The monomer-dimer equilibrium and thermodynamic of several ionic dyes (Neutral Red, Nile Blue A, Safranine T and Thionine) has been investigated by means of spectrophotometric and chemometrics methods. The dimerization constants of these ionic dyes have been determined by studying the dependence of their absorption spectra on the temperature in the range 20-75 °C at concentrations of Neutral Red (1.73 × 10 -5 M), Nile Blue A (3.94 × 10 -5 M), Safranine (6.59 × 10 -5 M) and Thionine (6.60 × 10 -5 M). The monomer-dimer equilibrium of these dyes has been determined by chemometrics refinement of the absorption spectra obtained by thermometric titrations performed. The processing of the data carried out for quantitative analysis of undefined mixtures, based on simultaneous resolution of the overlapping bands in the whole set of absorption spectra. The enthalpy and entropy of the dimerization reactions were determined from the dependence of the equilibrium constants to the temperature (van't Hoff equation).

Niazi, Ali; Yazdanipour, Ateesa; Ghasemi, Jahanbakhsh; Kubista, Mikael

2006-09-01

180

Application of some chemometric methods in conventional and derivative spectrophotometric analysis of acetaminophen and ascorbic acid.  

PubMed

The multivariate methods, principal component regression (PCR) and partial least squares (PLS) were tested as a calibration procedure for simultaneous ultraviolet spectrophotometric determination of acetaminophen (AC) and ascorbic acid (AA). Determination of these compounds is important because of their pharmacotherapeutic advantages. Due to spectral overlapping of AC and AA, PCR and PLS were used for construction of the calibration sets. The concentration linear range of AC and AA were 1.5-24.2 and 1.8-21.1 microg mL(-1) respectively. The absorption spectra were recorded from 215-310 nm. The minimum root mean square error of prediction (RMSEP) was 1.3507 and 0.4088 for AC and AA, by PLS, 0.7525 and 0.4015 by PCR in original data and 0.9454 and 0.2875, by PLS and 1.0386 and 0.4000 by PCR in derivative data. The procedure allows the simultaneous determination of AC and AA in synthetic mixtures and real sample solutions made up from pharmaceutical products, human serum and urine. PMID:20376831

Khajehsharifi, H; Eskandari, Z; Asadipour, A

2010-04-01

181

Determination of Trace Amounts of Lead Using the Flotation-spectrophotometric method  

PubMed Central

The present study describes a simple and highly selective method for separation, preconcentration and spectrophotometric determination of extremely low concentrations of lead. It is based on flotation of a complex of Pb2+ ions and Alizarin yellow between aqueous and n-hexane interface at pH = 6. The proposed procedure is also applied for determination of lead in both tap water and prepared sea water samples. Beer’s Law was obeyed over the concentration range of 3.86 × 10–8 To 8.20 × 10–7 molL?1 (8–170 ngmL?1) with an apparent molar absorptivity of 1.33 × 106 molL?1 cm?1 for a 100 mL aliquot of the water sample. The detection limit (n = 10) was 8.7 × 10–9 molL?1 (1.0 ngmL?1) and the Relative standard deviation (R.S.D), (n = 10) for 7.2 × 10–7 molL?1 (150 ngmL?1) of Pb (II) was 4.36%. A notable advantage of the method is that the determination of Pb (II) is free from the interference of almost all cations and ions found in the environment and waste water samples. The determination of Pb (II) in tap and synthetic seawater samples was also carried out by the present method. The results were satisfactorily comparable so that the applicability of the proposed method was confirmed to the real samples.

Shiri, Sabah; Delpisheh, Ali; Haeri, Ali; Poornajaf, Abdolhossein; Golzadeh, Babak; Shiri, Sina

2011-01-01

182

Chromium speciation in environmental samples using a solid phase spectrophotometric method  

NASA Astrophysics Data System (ADS)

A solid phase extraction technique is proposed for preconcentration and speciation of chromium in natural waters using spectrophotometric analysis. The procedure is based on sorption of chromium(III) as 4-(2-benzothiazolylazo)2,2'-biphenyldiol complex on dextran-type anion-exchange gel (Sephadex DEAE A-25). After reduction of Cr(VI) by 0.5 ml of 96% concentrated H2SO4 and ethanol, the system was applied to the total chromium. The concentration of Cr(VI) was calculated as the difference between the total Cr and the Cr(III) content. The influences of some analytical parameters such as: pH of the aqueous solution, amounts of 4-(2-benzothiazolylazo)2,2'-biphenyldiol (BTABD), and sample volumes were investigated. The absorbance of the gel, at 628 and 750 nm, packed in a 1.0 mm cell, is measured directly. The molar absorptivities were found to be 2.11 × 107 and 3.90 × 107 L mol-1 cm-1 for 500 and 1000 ml, respectively. Calibration is linear over the range 0.05-1.45 ?g L-1 with RSD of <1.85% (n = 8.0). Using 35 mg exchanger, the detection and quantification limits were 13 and 44 ng L-1 for 500 ml sample, whereas for 1000 ml sample were 8.0 and 27 ng L-1, respectively. Increasing the sample volume can enhance the sensitivity. No considerable interferences have been observed from other investigated anions and cations on the chromium speciation. The proposed method was applied to the speciation of chromium in natural waters and total chromium preconcentration in microwave digested tobacco, coffee, tea, and soil samples. The results were simultaneously compared with those obtained using an ET AAS method, whereby the validity of the method has been tested.

Amin, Alaa S.; Kassem, Mohammed A.

2012-10-01

183

Simultaneous spectrophotometric determination of Celecoxib and Diacerein in bulk and capsule by absorption correction method and chemometric methods  

NASA Astrophysics Data System (ADS)

Two methods, absorption correction and multivariate spectrophotometric methods were developed for simultaneous estimation of Celecoxib (CEL) and Diacerein (DIA) in combined dosage form. Absorption correction method involves direct estimation of DIA at wavelength 341 nm in which CEL has zero absorbance and shows no interference. For estimation of CEL, corrected absorbance was calculated at 253 nm due to the interference of DIA at this wavelength. Linearity was observed in the range of 6-22 ?g mL-1 for CEL and 3-11 ?g mL-1 for DIA. The method was validated as per ICH guidelines. Chemometric methods including classical least square (CLS), inverse least square (ILS), principal component regression (PCR) and partial least square (PLS) were studied for simultaneous determination of CEL and DIA in capsule using spectrophotometry. A set of 25 standard mixtures containing both drugs were prepared in range of 5-25 ?g mL-1 for CEL and 3-15 ?g mL-1 for DIA. Analytical figure of merit (FOM), such as sensitivity, selectivity, analytical sensitivity, limit of detection and limit of quantitation were determined for chemometric methods. The proposed methods were applied for determination of two components from combined dosage form.

Patel, N. S.; Nandurbarkar, V. P.; Patel, A. J.; Patel, S. G.

184

Selective kinetic spectrophotometric method for determination of gatifloxacin based on formation of its N-vinyl chlorobenzoquinone derivative  

NASA Astrophysics Data System (ADS)

A selective and simple kinetic spectrophotometric has been developed, for the first time, for the determination of gatifloxacin (GAT) in its dosage forms. The method was based on the formation of a colored N-vinyl chlorobenzoquinone derivative of GAT by its reaction with 2,3,5,6-tetrachloro-1,4-benzoquinone in presence of acetaldehyde. The formation of the colored product was monitored spectrophotometrically by measuring the absorbances at 655 nm. The factors affecting the reaction were studied and optimized. The stoichiometry of the reaction was determined, and the reaction pathway was postulated. Under the optimized conditions, the initial rate and fixed time (at 5 min) methods were utilized for constructing the calibration graphs. The graphs were linear in the concentration ranges of 2-100 and 10-140 ?g ml -1 with limits of detection of 0.84 and 3.5 ?g ml -1 for the initial rate and fixed time methods, respectively. The analytical performance of both methods was fully validated, and the results were satisfactory. The proposed methods were successfully applied to the determination of GAT in its commercial dosage forms. The label claim percentages were 99.7-100.5 and 98.2-99.5% for the initial rate and fixed time methods, respectively. Statistical comparison of the results with those of the reference method showed excellent agreement and proved that there was no significant difference in the accuracy and precision between the reference and the proposed methods. The proposed methods are superior to all the previously reported spectrophotometric methods in terms of the procedure simplicity and assay selectivity.

Darwish, Ibrahim A.; Sultan, Maha A.; Al-Arfaj, Hessa A.

2010-01-01

185

A PLS-based extractive spectrophotometric method for simultaneous determination of carbamazepine and carbamazepine-10,11-epoxide in plasma and comparison with HPLC.  

PubMed

Carbamazepine (CBZ) undergoes enzyme biotransformation through epoxidation with the formation of its metabolite, carbamazepine-10,11-epoxide (CBZE). A simple chemometrics-assisted spectrophotometric method has been proposed for simultaneous determination of CBZ and CBZE in plasma. A liquid extraction procedure was operated to separate the analytes from plasma, and the UV absorbance spectra of the resultant solutions were subjected to partial least squares (PLS) regression. The optimum number of PLS latent variables was selected according to the PRESS values of leave-one-out cross-validation. A HPLC method was also employed for comparison. The respective mean recoveries for analysis of CBZ and CBZE in synthetic mixtures were 102.57 (+/-0.25)% and 103.00 (+/-0.09)% for PLS and 99.40 (+/-0.15)% and 102.20 (+/-0.02)%. The concentrations of CBZ and CBZE were also determined in five patients using the PLS and HPLC methods. The results showed that the data obtained by PLS were comparable with those obtained by HPLC method. PMID:17307386

Hemmateenejad, Bahram; Rezaei, Zahra; Khabnadideh, Soghra; Saffari, Maryam

2007-11-01

186

A PLS-based extractive spectrophotometric method for simultaneous determination of carbamazepine and carbamazepine-10,11-epoxide in plasma and comparison with HPLC  

NASA Astrophysics Data System (ADS)

Carbamazepine (CBZ) undergoes enzyme biotransformation through epoxidation with the formation of its metabolite, carbamazepine-10,11-epoxide (CBZE). A simple chemometrics-assisted spectrophotometric method has been proposed for simultaneous determination of CBZ and CBZE in plasma. A liquid extraction procedure was operated to separate the analytes from plasma, and the UV absorbance spectra of the resultant solutions were subjected to partial least squares (PLS) regression. The optimum number of PLS latent variables was selected according to the PRESS values of leave-one-out cross-validation. A HPLC method was also employed for comparison. The respective mean recoveries for analysis of CBZ and CBZE in synthetic mixtures were 102.57 (±0.25)% and 103.00 (±0.09)% for PLS and 99.40 (±0.15)% and 102.20 (±0.02)%. The concentrations of CBZ and CBZE were also determined in five patients using the PLS and HPLC methods. The results showed that the data obtained by PLS were comparable with those obtained by HPLC method.

Hemmateenejad, Bahram; Rezaei, Zahra; Khabnadideh, Soghra; Saffari, Maryam

2007-11-01

187

Derivative-ratio spectrophotometric method for the determination of ternary mixture of aspirin, paracetamol and salicylic acid  

NASA Astrophysics Data System (ADS)

A derivative spectrophotometric method was developed for the assay of a ternary mixture of aspirin (ASP), paracetamol (PAR) and salicylic acid (SAL). The method is based on the use of the first and second derivatives of the ratio spectra and measurement at zero-crossing wavelengths. The ratio spectra were obtained by dividing the absorption spectrum of the mixture by that of one of the components. The concentration of the other components are then determined from their respective calibration curves treated similarly. The described method was applied for the determination of these combinations in synthetic mixtures and dosage forms. The results obtained were accurate and precise.

El-Yazbi, Fawzi A.; Hammud, Hassan H.; Assi, Sulaf A.

2007-10-01

188

Derivative-ratio spectrophotometric method for the determination of ternary mixture of aspirin, paracetamol and salicylic acid.  

PubMed

A derivative spectrophotometric method was developed for the assay of a ternary mixture of aspirin (ASP), paracetamol (PAR) and salicylic acid (SAL). The method is based on the use of the first and second derivatives of the ratio spectra and measurement at zero-crossing wavelengths. The ratio spectra were obtained by dividing the absorption spectrum of the mixture by that of one of the components. The concentration of the other components are then determined from their respective calibration curves treated similarly. The described method was applied for the determination of these combinations in synthetic mixtures and dosage forms. The results obtained were accurate and precise. PMID:17350884

El-Yazbi, Fawzi A; Hammud, Hassan H; Assi, Sulaf A

2007-10-01

189

Net analyte signal standard addition method (NASSAM) as a novel spectrofluorimetric and spectrophotometric technique for simultaneous determination, application to assay of melatonin and pyridoxine  

NASA Astrophysics Data System (ADS)

In this work a new modification of the standard addition method called "net analyte signal standard addition method (NASSAM)" is presented for the simultaneous spectrofluorimetric and spectrophotometric analysis. The proposed method combines the advantages of standard addition method with those of net analyte signal concept. The method can be applied for the determination of analyte in the presence of known interferents. The accuracy of the predictions against H-point standard addition method is not dependent on the shape of the analyte and interferent spectra. The method was successfully applied to simultaneous spectrofluorimetric and spectrophotometric determination of pyridoxine (PY) and melatonin (MT) in synthetic mixtures and in a pharmaceutical formulation.

Asadpour-Zeynali, Karim; Bastami, Mohammad

2010-02-01

190

Development and validation of sensitive kinetic spectrophotometric method for the determination of moxifloxacin antibiotic in pure and commercial tablets.  

PubMed

New, accurate, sensitive and reliable kinetic spectrophotometric method for the assay of moxifloxacin hydrochloride (MOXF) in pure form and pharmaceutical formulations has been developed. The method involves the oxidative coupling reaction of MOXF with 3-methyl-2-benzothiazolinone hydrazone hydrochloride monohydrate (MBTH) in the presence of Ce(IV) in an acidic medium to form colored product with lambda max at 623 and 660nm. The reaction is followed spectrophotometrically by measuring the increase in absorbance at 623nm as a function of time. The initial rate and fixed time methods were adopted for constructing the calibration curves. The linearity range was found to be 1.89-40.0?gmL(-1) for initial rate and fixed time methods. The limit of detection for initial rate and fixed time methods is 0.644 and 0.043?gmL(-1), respectively. Molar absorptivity for the method was found to be 0.89×10(4)Lmol(-1)cm(-1). Statistical treatment of the experimental results indicates that the methods are precise and accurate. The proposed method has been applied successfully for the estimation of moxifloxacin hydrochloride in tablet dosage form with no interference from the excipients. The results are compared with the official method. PMID:25596545

Ashour, Safwan; Bayram, Roula

2015-04-01

191

Successive determination of urinary protein and glucose using spectrophotometric sequential injection method.  

PubMed

A new sequential injection (SI) system with spectrophotometric detections has been developed for successive determination of protein and glucose. The protein assay is based on ion-association of protein with tetrabromophenolphthalein ethyl ester (TBPE) in the presence of Triton X-100 at pH 3.2. The blue product is monitored for absorbance at 607 nm. For glucose, hydrogen peroxide, generated by the oxidation of glucose in the presence of glucose oxidase immobilized on glass beads packed in a minicolumn, is monitored using iron-catalyzed oxidation reaction of p-anisidine to form a red colored product (520 nm). The SI procedure takes advantage in performing the protein assay during the incubation period for glucose oxidation. Linear ranges were up to 10 mg dL(-1) human serum albumin (HSA) with a limit of detection (LOD) (3sigma) of 0.3 mg dL(-1), and up to 12.5 mg dL(-1) glucose with LOD of 0.08 mg dL(-1). R.S.D.s (n=11) were 2.7% and 2.5% (for 1 mg dL(-1) and 5 mg dL(-1) HSA) and 1.4% (9 mg dL(-1) glucose). Sample throughput for the whole assay of both protein and glucose is 6 h(-1). The automated system has been demonstrated for the successive assay of protein and glucose in urine samples taken from diabetic disease patients, with good agreement with the other methods. This developed SI system is an alternative automation for screening for diabetic diagnosis. PMID:17996535

Kanchana, Watla-iad; Sakai, Tadao; Teshima, Norio; Katoh, Shuji; Grudpan, Kate

2007-12-01

192

Reaction of uranium (IV) with xenon difluoride by chemiluminescence, spectrophotometric, and spectrofluorimetric methods  

SciTech Connect

A study is made of the kinetics of the chemiluminescent reaction of oxidation of uranium (IV) by xenon difluoride in 1M HClO/sub 4/ U/sup 4 +/ + XeF/sub 2/ ..-->.. UO/sub 2//sup 2 +/ = h/eta/. The optical density D and the intensity of the photoluminescence of the solution I/sub PL/ were measured in parallel with recording of the luminescence intensity I/sub CL/. I/sub CL/ attains a maximum value some time after the beginning of the reaction, after which it decays exponentially. On the kinetic curves of the time dependence of D and I/sub PL/ an induction period is observed, the extent of which depends on concentrations of reagents and temperature of the solution. The maximum of I/sub CL/ coincides with the end of the induction period if the measurements are carried out under identical conditions. The rate of the reaction after the induction period is described by a first order equation in U/sup (IV)/. The rate constants of the reaction, obtained by chemiluminescence, spectrophotometric, and spectrofluorimetric methods, have close values 2.0 +- 0.4, 1.8 +- 0.3, and 2.1 +- 0.3 sec/sup /minus/1/ x 10/sup 2/, respectively. On the basis of the results obtained, we conclude that the stages of formation of UO/sub 2//sup 2 +/ and of chemiluminescence coincide, i.e., formation of the excited state (UD/sub 2//sup 2 +/) and of chemiluminescence coincide, i.e., formation of the excited state (UD/sub 2//sup 2 +/)* takes place during the reaction. It is proposed and experimentally verified that the reaction passes through an intermediate stage of formation of uranyl ion UO/sub 2//sup +/.

Mamykin, A.V.; Kazakov, V.P.

1988-07-01

193

Is it possible to screen for milk or whey protein adulteration with melamine, urea and ammonium sulphate, combining Kjeldahl and classical spectrophotometric methods?  

PubMed

The Kjeldahl method and four classic spectrophotometric methods (Biuret, Lowry, Bradford and Markwell) were applied to evaluate the protein content of samples of UHT whole milk deliberately adulterated with melamine, ammonium sulphate or urea, which can be used to defraud milk protein and whey contents. Compared with the Kjeldahl method, the response of the spectrophotometric methods was unaffected by the addition of the nitrogen compounds to milk or whey. The methods of Bradford and Markwell were most robust and did not exhibit interference subject to composition. However, the simultaneous interpretation of results obtained using these methods with those obtained using the Kjeldahl method indicated the addition of nitrogen-rich compounds to milk and/or whey. Therefore, this work suggests a combination of results of Kjeldahl and spectrophotometric methods should be used to screen for milk adulteration by these compounds. PMID:23993532

Finete, Virgínia de Lourdes Mendes; Gouvêa, Marcos Martins; Marques, Flávia Ferreira de Carvalho; Netto, Annibal Duarte Pereira

2013-12-15

194

Spectroflourometric and Spectrophotometric Methods for the Determination of Sitagliptin in Binary Mixture with Metformin and Ternary Mixture with Metformin and Sitagliptin Alkaline Degradation Product  

PubMed Central

Simple, accurate and precise spectroflourometric and spectrophotometric methods have been developed and validated for the determination of sitagliptin phosphate monohydrate (STG) and metformin HCL (MET). Zero order, first derivative, ratio derivative spectrophotometric methods and flourometric methods have been developed. The zero order spectrophotometric method was used for the determination of STG in the range of 50-300 ?g mL-1. The first derivative spectrophotometric method was used for the determination of MET in the range of 2–12 ?g mL-1 and STG in the range of 50-300 ?g mL-1 by measuring the peak amplitude at 246.5 nm and 275 nm, respectively. The first derivative of ratio spectra spectrophotometric method used the peak amplitudes at 232 nm and 239 nm for the determination of MET in the range of 2–12 ?g mL-1. The flourometric method was used for the determination of STG in the range of 0.25-110 ?g mL-1. The proposed methods used to determine each drug in binary mixture with metformin and ternary mixture with metformin and sitagliptin alkaline degradation product that is obtained after alkaline hydrolysis of sitagliptin. The results were statistically compared using one-way analysis of variance (ANOVA). The methods developed were satisfactorily applied to the analysis of the pharmaceutical formulations and proved to be specific and accurate for the quality control of the cited drugs in pharmaceutical dosage forms. PMID:23675222

El-Bagary, Ramzia I.; Elkady, Ehab F.; Ayoub, Bassam M.

2011-01-01

195

[Application of HPLC-UV method for aripiprazole determination in serum].  

PubMed

Aripiprazole is a new drug applied in schizophrenia treatment. There are not strict indications for aripiprazole therapeutic drug monitoring. Despite, serum aripiprazole measuring would help control the drug doses effectiveness. The drug monitoring can eliminate overdosing, adverse effects and let control proper drug ingestion. The aim of the paper was to develop a simple method for aripiprazole determination in serum for therapeutic drug monitoring. High performance liquid chromatography with spectrophotometric detection (HPLC-UV) was used. Resolution was performed on LC-8 column; moving phase was solution 0,025M trimethylammonium buffer: acetonitrile (62:38). Isocratic flow was 1,2 ml/min; internal standard (IS) was promazine; monitored wavelength was lambda=214 nm. The validation parameters were: limits of linearity (LOL) 100-800 ng/ml, limit of detection (LOD) 10 ng/ml, limit of quantity (LOQ) 100 ng/ml. Coefficient of variation (CV) describing accuracy and precision didn't cross 10%. The method was useful for therapeutic drug monitoring in serum of patients treated with aripiprazole. PMID:23421079

Synowiec, Anna; Gomó?ka, Ewa; Zyss, Tomasz; Zieba, Andrzej; Florek, Ewa; Piekoszewski, Wojciech

2012-01-01

196

A rapid spectrophotometric method for the quantitative estimation of octadecyl p-coumarates  

NASA Astrophysics Data System (ADS)

The UV spectrum of octadecyl p-coumarates gives a peak at ?max(MeOH) = 308.6 nm (log ? = 4.13). On addition of alkali, the peak undergoes a bathochromic shift to 358.2 nm with a hyperchromic effect. A linear relationship found between the concentration of octadecyl p-coumarates and the hyperchromic effect can be used to quantitatively estimate octadecyl p-coumarates in samples devoid of other compounds exhibiting the similar hyperchromic effect. The method may also be useful for quantitative comparison of total alkyl coumarates in plant samples.

Nidiry, E. S. J.; Lokesha, A. N.

2013-07-01

197

Simultaneous determination of iron and manganese in water using artificial neural network catalytic spectrophotometric method  

NASA Astrophysics Data System (ADS)

A new analytical method using Back-Propagation (BP) artificial neural network and kinetic spectrophotometry for simultaneous determination of iron and magnesium in tap water, the Yellow River water and seawater is established. By conditional experiments, the optimum analytical conditions and parameters are obtained. Levenberg-Marquart (L-M) algorithm is used for calculation in BP neural network. The topological structure of three-layer BP ANN network architecture is chosen as 15-16-2 (nodes). The initial value of gradient coefficient µ is fixed at 0.001 and the increase factor and reduction factor of µ take the default values of the system. The data are processed by computers with our own programs written in MATLAB 7.0. The relative standard deviation of the calculated results for iron and manganese is 2.30% and 2.67% respectively. The results of standard addition method show that for the tap water, the recoveries of iron and manganese are in the ranges of 98.0%-104.3% and 96.5%-104.5%, and the RSD is in the range of 0.23%-0.98%; for the Yellow River water (Lijin district of Shandong Province), the recoveries of iron and manganese are in the ranges of 96.0%-101.0% and 98.7%-104.2%, and the RSD is in the range of 0.13%-2.52%; for the seawater in Qingdao offshore, the recoveries of iron and manganese are in the ranges of 95.3%-104.8% and 95.3%-104.7%, and the RSD is in the range of 0.14%-2.66%. It is found that 21 common cations and anions do not interfere with the determination of iron and manganese under the optimum experimental conditions. This method exhibits good reproducibility and high accuracy in the determination of iron and manganese and can be used for the simultaneous determination of iron and manganese in tap water and natural water. By using the established ANN-catalytic spectrophotometric method, the iron and manganese concentrations of the surface seawater at 11 sites in Qingdao offshore are determined and the level distribution maps of iron and manganese are drawn.

Ji, Hongwei; Xu, Yan; Li, Shuang; Xin, Huizhen; Cao, Hengxia

2012-09-01

198

Extractive spectrophotometric methods for the determination of doxepin hydrochloride in pharmaceutical preparations using titanium (IV) and iron (III) thiocyanate complexes.  

PubMed

Two simple, precise, and accurate extractive spectrophotometric methods have been developed for the determination of doxepin hydrochloride in pharmaceutical preparations. The methods are based on the formation of ion association complexes of doxepin with titanium (IV) and iron (III) thiocyanate complexes in acidic medium. The produced compounds are insoluble in water but well soluble in some organic solvents. They are extracted with mixtures of butyl alcohol-chloroform (2:3, v/v) and (1:4, v/v) and measured spectrophotometrically at 400 and 490 nm for DOX-Ti-SCN and DOX-Fe(III)-SCN methods, respectively. Beer's law was obeyed in the concentration ranges of 5-50 and 3-30 microg/ml with molar absorptivity of 7.12 x 10(3) and 1.36 x 10(4) l mol(-1) cm(-1) for DOX-Ti-SCN and DOX-Fe-SCN systems, respectively. The proposed methods have been successfully applied for the analysis of the drug in dosage forms. No interference was observed from common pharmaceutical adjuvants. The methods have been also used for the determination of the drug in the presence of its degradation product. Statistical comparison of the obtained results with the reference methods shows excellent agreement and indicates no significant difference in accuracy and precision. PMID:15652371

Misiuk, Wies?awa

2005-01-01

199

Quantification of ranitidine hydrochloride in the presence of its decomposition product by spectrophotometric methods. Application for kinetic study.  

PubMed

Three spectrophotometric methods, based on a spectral analysis, are proposed for quantification of ranitidine hydrochloride (RHCl) in the presence of its decomposition product (R-ox) without isolation from the matrix. One of them is a zero-crossing derivative-spectrophotometry. A value of the first derivative at 332 nm generated by the Savitzky-Golay algorithm (delta lambda = 22 nm and the first polynomial degree) allows for quantification of RHCI in the concentration range 0.5-35.1 microg/mL. The second proposed spectrophotometric procedure, called Vierordt method, utilizes an additivity of the absorbance. The assay of studied compound was realized by the direct reading of absorbance at 312 nm and 202 nm for ranitidine hydrochloride and its decomposition product, respectively. The quantitative results were obtained by resolving of an appropriate system of equations. The third method is based on the bivariate calibration algorithm. The absorbance values were measured at optimum wavelengths found by Kaiser method at 228 nm and 202 nm and used for the quantification of RHCI in the presence of its decomposition product. The Beer's law was obeyed in the concentration range 0.5-35.1 microg/mL for RHCl. The discussion of applicability of all elaborated methods is presented. The proposed methods were applied for assay of ranitidine hydrochloride contents in its preparation Ranigast and for investigation of kinetics of its reaction with hydrogen peroxide. PMID:21485289

Sokó?, Aneta; Karpi?ska, Joanna; Talecka, Renata; Starczewska, Barbara

2011-01-01

200

Development and validation of zero and first-order derivative area under curve spectrophotometric methods for the determination of entacapone in bulk material and in tablets  

PubMed Central

Aim: The aim of this work is to establish two simple, economical, and rapid spectrophotometric methods for the quantification of entacapone in bulk material and in tablets. Further, this study is designed to validate the developed methods as per ICH guidelines. Materials and Methods: In Methods I and II, a stock standard solution was prepared by dissolving 10 mg of entacapone in 100 mL of 10% v/v acetonitrile to obtain a concentration of 100 ?g/mL. After suitable dilution, 10 ?g/mL of entacapone was prepared and scanned in the UV-visible range 500–200 nm; entacapone showed a maximum absorbance at 384.40 nm. In Method I, area under curve (AUC) of the zero-order spectrum was recorded between 348.00 and 410.20 nm. While, in Method II, zero-order spectra were derivatized into first-order, and the AUC was recorded between 386.40 and 460.20 nm. For a linearity study, series of dilutions were prepared from stock solutions. Results: In Method I, and II, entacapone followed linearity in the concentration range of 2–12 ?g/mL and 5–30 ?g/mL with (r2>0.999). The amounts of entacapone estimated by both these methods were found to be 99.24 ± 0.054 and 98.68 ± 1.04, respectively. Conclusion: The developed methods are simple, precise, rugged, robust, and economical. Both these methods can be used for routine analysis of entacapone from its tablet formulation. PMID:23781472

Chalikwar, S. S.; Shirkhedkar, A. A.; Bagul, M. A.; Jain, P. S.; Surana, S. J.

2012-01-01

201

A novel methodology for analysis of enantiomers through determination of their critical micelle concentrations using spectrophotometric method.  

PubMed

A novel methodology for analysis of enantiomer composition of chiral compounds based on measuring of their critical micelle concentration by using spectrophotometric technique is introduced. The proposed method does not require any chiral selector and the corresponding process is simple, fast, reproducible, and inexpensive. The procedure was successfully applied for analysis of naproxen. The critical micelle concentration data showed that (R)-naproxen could be determined with an RSD of 1.1% and a relative error of -5.6% when a real sample containing the racemic mixture of naproxen with a total concentration of 0.04 mM was tested. PMID:23708436

Absalan, Ghodratollah; Alipour, Yousef

2013-09-01

202

pH-Induced Difference Spectrophotometric Methods for the Determination of Oxyphenbutazone in Some Pharmaceutical Formulations  

Microsoft Academic Search

Two pH- induced difference- spectrophotometric procedures for the determination of oxyphenbutazone in pharmaceutical formulations are reported. Both procedures depend upon the sensitivity of the ultraviolet spectrum of oxyphenbutazone towards the pH of the solvent medium. In one procedure, the absorbance difference of oxyphenbutazone in an acid solvent (0.01 NHCl) and in an alkaline one (0.01 N NaOH) is measured at

Sawsan M. Amer; Sayed M. Hassans; Mohammed F. El-tarras

1980-01-01

203

Spectrophotometric determination of carminic acid in human plasma and fruit juices by second order calibration of the absorbance spectra-pH data matrices coupled with standard addition method.  

PubMed

A simple analytical method based on the second-order calibration of the pH gradient spectrophotometric data was developed for assay of carminic acid (CA) in human plasma and orange juice over the concentration range of 1.5-14.0microM. The multi-way data analysis method was coupled with standard addition to encounter the significant effects of plasma and juices matrices on the acid-base behavior and UV-vis. absorbance spectra of CA. Thus, the standard addition three-way calibration data of plasma or fruit juices samples were analyzed by parallel factor analysis (PARAFAC) and the concentration related scores were used to derive a standard addition plot such as one obtained in univariate standard addition method. The number of PARAFAC components was obtained utilizing different criteria such as core consistency and residual errors through pf-test implementation. The applicability of the proposed method was evaluated by analysis of human plasma and fruit juices spiked with different levels of standard CA solutions. The results confirmed the success of the proposed method in the analysis of pH gradient spectrophotometric data for determination of CA. The recoveries were between 86.7 and 106.7. PMID:20441865

Samari, Fayezeh; Hemmateenejad, Bahram; Shamsipur, Mojtaba

2010-05-14

204

A New Spectrophotometric Method for Determination of Selenium in Cosmetic and Pharmaceutical Preparations after Preconcentration with Cloud Point Extraction  

PubMed Central

A simple, rapid, and sensitive spectrophotometric method for the determination of trace amounts of selenium (IV) was described. In this method, all selenium spices reduced to selenium (IV) using 6?M?HCl. Cloud point extraction was applied as a preconcentration method for spectrophotometric determination of selenium (IV) in aqueous solution. The proposed method is based on the complexation of Selenium (IV) with dithizone at pH?

Soruraddin, Mohammad Hosein; Heydari, Rouhollah; Puladvand, Morteza; Zahedi, Mir Mehdi

2011-01-01

205

A spectrophotometric method for the quantification of an enzyme activity producing 4-substituted phenols: determination of toluene-4-monooxygenase activity.  

PubMed

A spectrophotometric method for the quantitative determination of an enzyme activity resulting in the accumulation of 4-substituted phenols is described in this article. Toluene-4-monooxygenase (T4MO) activity in whole cells of Pseudomonas mendocina KR1 is used to demonstrate this method. This spectrophotometric assay is based on the coupling of T4MO activity with tyrosinase activity. The 4-substituted phenol, produced by the action of T4MO on the aromatic ring of a substituted arene, is a substrate for tyrosinase, which converts phenols to o-quinones. The latter react with the nucleophile 3-methyl-2-benzothiazolinone hydrazone (MBTH) to produce intensely colored products that absorb light maximally at different wavelengths, depending on the phenolic substrate used. The incubation of whole cells of P. mendocina KRI with fluorobenzene resulted in the accumulation of 4-fluorophenol. The coupling of T4MO activity with tyrosinase activity in the presence of fluorobenzene resulted in the formation of a colored product absorbing maximally at 480 nm. The molar absorptivity (epsilon) value for the o-quinone-MBTH adduct formed from 4-fluorophenol was determined experimentally to be 12,827 M(-1) cm(-1) with a linear range of quantification between 2.5 and 75 microM. The whole cell assay was run as a continuous indirect assay. The initial rates of T4MO activity toward fluorobenzene, as determined spectrophotometrically, were 61.8+/-4.4 nmol/min/mg P. mendocina KR1 protein (using mushroom tyrosinase), 64.9+/-4.6 nmol/min/mg P. mendocina KR1 protein (using cell extracts Pseudomonas putida F6), and, as determined by HPLC analysis, 62.6+/-1.4 nmol/min/mg P. mendocina KR1 protein. PMID:16061193

Nolan, Louise C; O'Connor, Kevin E

2005-09-15

206

A sensitive spectrophotometric method for the determination of pregabalin in bulk, pharmaceutical formulations and in human urine samples.  

PubMed

A simple and sensitive spectrophotometric method was developed and validated for the determination of pregabalin in bulk, pharmaceutical formulations and in human urine samples. The method was based on the reaction of drug with the mixture of potassium iodate and potassium iodide. The method was linear in the range of 0.5-3.5 ?g/ml. There is no official method for the determination of pregabalin. The absorbance was measured at 353 nm. The method was validated with respect to accuracy, precision, specificity, ruggedness, robustness, limit of detection and limit of quantitation. This method was used successfully for the quality assessment of five pregabalin drug products and in human urine samples with good precision and accuracy. PMID:23675167

Gujral, Rajinder Singh; Haque, Sk Manirul; Shanker, Prem

2009-12-01

207

Simultaneous spectrophotometric determination of benzoic acid, sorbic acid, and ascorbic acid using a net analyte signal-based method.  

PubMed

The net analyte preprocessing/classical least-squares (NAP/CLS) method is a simple chemometric method that has been used for the simultaneous spectrophotometric determination of benzoic acid, sorbic acid, and ascorbic acid. The obtained results indicated that the performances of the NAP/CLS and partial least-squares methods were almost identical. The net analyte signal (NAS) concept was also used to calculate multivariate analytical figures of merit, such as LOD, selectivity, and sensitivity. Wavelength selection was applied based on the concept of NAS regression, and improved the method performance in samples containing nonmodeled interferences. The method afforded recoveries in the range of 98-105%. The proposed method was successfully applied to determination of the analytes in an Iranian soft drink. PMID:20166599

Naseri, Abdolhossein; Ghorbani-Kalhor, Ebrahim; Vallipour, Javad; Jafari, Samira; Shahverdizadeh, Gholam Hossein; Asadpour-Zeynali, Karim

2009-01-01

208

Application of the ratio difference spectrophotometry to the determination of ibuprofen and famotidine in their combined dosage form; Comparison with previously published spectrophotometric methods.  

PubMed

Ratio difference spectrophotometric method was developed for the determination of ibuprofen and famotidine in their mixture form. Ibuprofen and famotidine were determined in the presence of each other by the ratio difference spectrophotometric (RD) method where linearity was obtained from 50 to 600?g/mL and 2.5 to 25?g/mL for ibuprofen and famotidine, respectively. The suggested method was validated according to ICH guidelines and successfully applied for the analysis of ibuprofen and famotidine in their pharmaceutical dosage forms without interference from any additives or excipients. PMID:25733252

Zaazaa, Hala E; Elzanfaly, Eman S; Soudi, Aya T; Salem, Maissa Y

2015-05-15

209

UV partial least-squares calibration and liquid chromatographic methods for direct quantitation of levofloxacin in urine.  

PubMed

Levofloxacin was determined in human urine samples by application of a spectrophotometric multivariate calibration partial least-squares (PLS-1) method. A calibration set consisting of standards was prepared by using a multilevel multifactor experimental design. In order to ensure accurate results, the calibration matrix included a urine sample free of levofloxacin (i.e., urine blank). The components of the calibration matrix were levofloxacin and urine. The concentration of levofloxacin ranged from 0.5 to 16.5 microg/mL. Different urine concentrations were used as the second component of the calibration matrix in order to include the information inherent in the changes in the UV spectrum for urine upon dilution. In addition, a high-performance liquid chromatographic method was proposed. In this method, a Shim-pack amino column was used at ambient temperature with a mobile phase of 25 mM potassium dihydrogen phosphate (pH adjusted to 3.1 with phosphoric acid)-acetonitrile (70 + 30, v/v), and the flow rate was 1 mL/min. UV detection at 293 nm was used for quantitation. The proposed methods were applied to the determination of the dissolution rate for tablets containing levofloxacin. The urinary excretion pattern for the cumulative amount of levoflacin excreted was also calculated. PMID:17955970

El-Gindy, Alaa; Emara, Samy; Mostafa, Ahmed

2007-01-01

210

Stability indicating spectrophotometric and spectrodensitometric methods for the determination of diatrizoate sodium in presence of its degradation product  

NASA Astrophysics Data System (ADS)

Three sensitive, selective, and precise stability indicating methods for the determination of the X-ray contrast agent, diatrizoate sodium (DTA), in the presence of its acidic degradation product (highly cytotoxic 3,5 diamino metabolite) and in pharmaceutical formulation were developed and validated. The first method is a first derivative (D1) spectrophotometric one, which allows the determination of DTA in the presence of its degradate at 231.2 nm (corresponding to zero crossing of the degradate) over a concentration range of 2-24 ?g/mL with mean percentage recovery 99.95 ± 0.97%. The second method is the first derivative of the ratio spectra (DD1) by measuring the peak amplitude at 227 nm over the same concentration range as D1 spectrophotometric method, with mean percentage recovery 99.99 ± 1.15%. The third method is a TLC-densitometric one, where DTA was separated from its degradate on silica gel plates using chloroform:methanol:ammonium hydroxide (20:10:2 by volume) as a developing system. This method depends on quantitative densitometric evaluation of thin layer chromatogram of DTA at 238 nm over a concentration range of 4-20 ?g/spot, with mean percentage recovery 99.88 ± 0.89%. The selectivity of the proposed methods was tested using laboratory-prepared mixtures. The proposed methods have been successfully applied to the analysis of DTA in pharmaceutical dosage forms without interference from other dosage form additives. The results were statistically compared with the official US pharmacopeial method. No significant difference for either accuracy or precision was observed.

Abd El-Rahman, Mohamed K.; Riad, Safaa M.; Abdel Gawad, Sherif A.; Fawaz, Esraa M.; Shehata, Mostafa A.

2015-02-01

211

Studies on the UV spectrum of poly(?-glutamic acid) based on development of a simple quantitative method.  

PubMed

A simple and valid ultraviolet (UV) spectrophotometric method for the determination of poly(?-glutamic acid) is developed. The method is based on the UV absorption spectrum of ?-PGA in aqueous solution, which exhibits a maximum absorption wavelength at 216 nm. The results obtained were comparable to those obtained with the reported high-performance liquid chromatography (HPLC) method according to ICH guidelines. Under the proposed procedure, the calibration graph is linear over the range of 20-200 ?g/ml with regression correlation coefficient of 0.9997. Precision (%R.S.D.<1.50) and recovery (%R.>99.29%) are good. The limit of detection (LOD) and limit of quantitation (LOQ) are 0.39 and 1.19 ?g/ml, respectively. These results agree well with those of HPLC method. Its spectrum properties studies showed that the spectrum of ?-PGA remarkably changed with an increase in temperature due to ?-PGA was digested into glutamate monomer. In spite of this, the determining procedure could carried out in a wide temperature range (25-50°C). In addition, the method is not influenced by the molecular weight, but the measurement system need to control in pH 3.0-10.0 and ionic strength not more than 0.5M. The proposed method is applied successfully for high-throughput quantification of poly(?-glutamic acid) in biological samples. The advantages of the UV method are simplicity of operation, rapidity, sensitive, low-cost and high-throughput. PMID:22521620

Zeng, Wei; Chen, Guiguang; Zhang, Yunkai; Wu, Kongyang; Liang, Zhiqun

2012-01-01

212

A comparative study of novel spectrophotometric methods based on isosbestic points; application on a pharmaceutical ternary mixture.  

PubMed

This work represents the application of the isosbestic points present in different absorption spectra. Three novel spectrophotometric methods were developed, the first method is the absorption subtraction method (AS) utilizing the isosbestic point in zero-order absorption spectra; the second method is the amplitude modulation method (AM) utilizing the isosbestic point in ratio spectra; and third method is the amplitude summation method (A-Sum) utilizing the isosbestic point in derivative spectra. The three methods were applied for the analysis of the ternary mixture of chloramphenicol (CHL), dexamethasone sodium phosphate (DXM) and tetryzoline hydrochloride (TZH) in eye drops in the presence of benzalkonium chloride as a preservative. The components at the isosbestic point were determined using the corresponding unified regression equation at this point with no need for a complementary method. The obtained results were statistically compared to each other and to that of the developed PLS model. The specificity of the developed methods was investigated by analyzing laboratory prepared mixtures and the combined dosage form. The methods were validated as per ICH guidelines where accuracy, repeatability, inter-day precision and robustness were found to be within the acceptable limits. The results obtained from the proposed methods were statistically compared with official ones where no significant difference was observed. PMID:24589996

Lotfy, Hayam M; Saleh, Sarah S; Hassan, Nagiba Y; Salem, Hesham

2014-05-21

213

A simple spectrophotometric method for determination of zirconium or hafnium in selected molybdenum-base alloys  

NASA Technical Reports Server (NTRS)

A simple analytical procedure is described for accurately and precisely determining the zirconium or hafnium content of molybdenum-base alloys. The procedure is based on the reaction of the reagent Arsenazo III with zirconium or hafnium in strong hydrochloric acid solution. The colored complexes of zirconium or hafnium are formed in the presence of molybdenum. Titanium or rhenium in the alloy have no adverse effect on the zirconium or hafnium complex at the following levels in the selected aliquot: Mo, 10 mg; Re, 10 mg; Ti, 1 mg. The spectrophotometric measurement of the zirconium or hafnium complex is accomplished without prior separation with a relative standard deviation of 1.3 to 2.7 percent.

Dupraw, W. A.

1972-01-01

214

Application of Orthogonal Functions and Computerized Compensation Methods to Spectrophotometric Analysis of Vitamin A in the Presence of its Degradation Products  

Microsoft Academic Search

Two spectrophotometric methods, the orthogonal function method and computerized compensation method are described for the determination of vitamin A in the presence of its degradation products. The first is based on selecting six-points quadratic order of the orthogonal polynomial over the wavelengths range 302–342 nm at eight-nm intervals. The second is dependent on the selection of the exact balance point

Magda H. Barary

1991-01-01

215

Ultra-sensitive quantification of sub-nanomolar levels of iodine in blood serum samples by kinetic-spectrophotometric method.  

PubMed

A simple and sensitive kinetic-spectrophotometric method is developed for the determination of trace amounts of iodine in blood serum samples based on its catalytic effect on the oxidation of Nile Blue A by potassium bromate in sulfuric acid medium and at 25°C. The absorbance is measured at 595.5 nm with the fixed-time method. The optimization of the operating conditions regarding concentration of the reagents, temperature, and interferences are also investigated. The calibration curve is linear over the concentration range between 20.0 to 500.0 ng ml(-1) of iodine with good precision and accuracy. The detection limit of the method is down to 12.0 ng ml(-1). The relative standard deviation for a standard solution of 100.0 ng ml(-1) of iodine is 1.32% (n?=?10). The proposed method provides a highly sensitive, selective, and relatively rapid assay for iodine at ultra trace level without any pre-concentration and separation step. The method was applied to the determination of iodine in blood serum samples. The analytical results of the real samples were in excellent agreement with standard method. PMID:21732074

Mortazavi, S S; Noorizadeh, H; Hushmandfar, R; Farmany, Abbas

2011-12-01

216

Development of a spectrophotometric method for on-site analysis of peroxygens during in-situ chemical oxidation applications.  

PubMed

Activated peroxygens are frequently used as active agents in in-situ chemical oxidation (ISCO) contaminated site remediation applications, and fast and simple quantitative analysis of these species on site is necessary. In this work, the use of a spectrophotometric method based on classic iodometric titration is studied for quantitative analysis of S2O8(2-) and H2O2. Instead of a back-titration step, the absorbance of the yellow iodide colour was measured at 352 nm in the presence of a bicarbonate buffer. A linear calibration curve was obtained from 0 to 0.1 mM for both S2O8(2-) and H2O2. By dilution, the method can be used for all concentrations typically applied in the field. Concerning pH dependence, neutral pH levels caused no significant error whereas pH levels above 8 caused a 9% and 6% deviation from the theoretical peroxygen concentrations. Furthermore, the method showed little dependence on other matrix components, and absorbance was stable (<2% change) for more than a week. Overall, the method proved to be fast and simple, which are important features for a field method. PMID:25429454

Bennedsen, Lars Rønn; Søgaard, Erik Gydesen; Muff, Jens

2014-01-01

217

Bivariate versus multivariate smart spectrophotometric calibration methods for the simultaneous determination of a quaternary mixture of mosapride, pantoprazole and their degradation products.  

PubMed

The ability of bivariate and multivariate spectrophotometric methods was demonstrated in the resolution of a quaternary mixture of mosapride, pantoprazole and their degradation products. The bivariate calibrations include bivariate spectrophotometric method (BSM) and H-point standard addition method (HPSAM), which were able to determine the two drugs, simultaneously, but not in the presence of their degradation products, the results showed that simultaneous determinations could be performed in the concentration ranges of 5.0-50.0 microg/ml for mosapride and 10.0-40.0 microg/ml for pantoprazole by bivariate spectrophotometric method and in the concentration ranges of 5.0-45.0 microg/ml for both drugs by H-point standard addition method. Moreover, the applied multivariate calibration methods were able for the determination of mosapride, pantoprazole and their degradation products using concentration residuals augmented classical least squares (CRACLS) and partial least squares (PLS). The proposed multivariate methods were applied to 17 synthetic samples in the concentration ranges of 3.0-12.0 microg/ml mosapride, 8.0-32.0 microg/ml pantoprazole, 1.5-6.0 microg/ml mosapride degradation products and 2.0-8.0 microg/ml pantoprazole degradation products. The proposed bivariate and multivariate calibration methods were successfully applied to the determination of mosapride and pantoprazole in their pharmaceutical preparations. PMID:23802428

Hegazy, M A; Yehia, A M; Moustafa, A A

2013-05-01

218

Novel spectrophotometric method for determination of some macrolide antibiotics in pharmaceutical formulations using 1,2-naphthoquinone-4-sulphonate  

NASA Astrophysics Data System (ADS)

New, simple and rapid spectrophotometric method has been developed and validated for the assay of two macrolide drugs, azithromycin (AZT) and erythromycin (ERY) in pure and pharmaceutical formulations. The proposed method was based on the reaction of AZT and ERY with sodium 1,2-naphthoquinone-4-sulphonate (NQS) in alkaline medium at 25 °C to form an orange-colored product of maximum absorption peak at 452 nm. All variables were studied to optimize the reaction conditions and the reaction mechanism was postulated. Beer's law was obeyed in the concentration range 1.5-33.0 and 0.92-8.0 ?g mL-1 with limit of detection values of 0.026 and 0.063 ?g mL-1 for AZT and ERY, respectively. The calculated molar absorptivity values are 4.3 × 104 and 12.3 × 104 L mol-1 cm-1 for AZT and ERY, respectively. The proposed methods were successfully applied to the determination of AZT and ERY in formulations and the results tallied well with the label claim. The results were statistically compared with those of an official method by applying the Student's t-test and F-test. No interference was observed from the concomitant substances normally added to preparations.

Ashour, Safwan; Bayram, Roula

2012-12-01

219

Validated Stability indicating Spectrophotometric Method for the Determination of Acetazolamide in Dosage Forms through Complex Formation with Palladium (II)  

PubMed Central

A simple and sensitive spectrophotometric method was developed for the determination of acetazolamide (ACM) in pure form and pharmaceutical preparations. The proposed method is based on the complex formation of acetazolamide with Palladium (II) chloride in acetate buffer pH5.4 and measuring the absorbance at 308 nm. The absorbance- concentration plot was rectilinear over the concentration range of 5-70 ?g/ml with a minimum detection limit (LOD) of 0.98 ?g/ml, limit of quantification (LOQ) of 2.96 ?g/ml, and a molar absorptivity ?=2.7 × 103 L/mol.cm. The factors affecting the absorbance of the formed complex were carefully studied and optimized. The composition of the complex as well as its stability constant was also investigated. The proposed method was applied for the determination of acetazolamide in its tablets and the results obtained were favorably compared with those obtained using the official method. A proposal of the reaction pathway was postulated. PMID:23675188

Walash, M. I.; El-Brashy, A.; El-Enany, N.; Wahba, M. E. K.

2010-01-01

220

Application of smart spectrophotometric methods and artificial neural network for the simultaneous quantitation of olmesartan medoxamil, amlodipine besylate and hydrochlorothiazide in their combined pharmaceutical dosage form  

PubMed Central

Background New, simple and specific spectrophotometric methods and artificial neural network (ANN) were developed and validated in accordance with ICH guidelines for the simultaneous estimation of Olmesartan (OLM), Amlodipine (AML), and Hydrochlorothiazide (HCT) in commercial tablets. Results For spectrophotometric methods: First, Amlodipine (AML) was determined by direct spectrophotometry at 359 nm and by application of the ratio subtraction, the AML spectrum was removed from the mixture spectra. Then Hydrochlorothiazide (HCT) was determined directly at 315 nm without interference from Olmesartan medoxamil (OLM) which could be determined using the isoabsorptive method. The calibration curve is linear over the concentration range of 5–40, 2.5-40 and 2–40 ?g mL-1 for AML, OLM and HCT, respectively. ANN (as a multivariate calibration method) was also applied for the simultaneous determination of the three analytes in their combined pharmaceutical dosage form using spectral region from 230–340 nm. Conclusions The proposed methods were successfully applied for the assay of the three analytes in laboratory prepared mixtures and combined pharmaceutical tablets with excellent recoveries. No interference was observed from common pharmaceutical additives. The results were favorably compared with those obtained by a reference spectrophotometric method. The methods are validated according to the ICH guidelines and accuracy, precision and repeatability are found to be within the acceptable limit. PMID:23374392

2013-01-01

221

A sequential injection spectrophotometric method for the determination of penicillamine in pharmaceutical products by complexation with iron(III) in acidic media  

Microsoft Academic Search

A simple, robust and sensitive sequential injection spectrophotometric method for the assay of penicillamine (PA) in pharmaceutical formulations is developed. The method was based on the complex formation when PA is reacted with iron(III) solution in hydrochloric acid media. The deep blue colored PA–iron(III) complex produced is monitored at a maximum wavelength of 600 nm. A five level orthogonal array

Fakhr Eldin O. Suliman; Haider A. J. Al-Lawati; Salma M. Z. Al-Kindy; Imad Eldin M. Nour; Salama B. Salama

2003-01-01

222

New validated liquid chromatographic and chemometrics-assisted UV spectroscopic methods for the determination of two multicomponent cough mixtures in syrup.  

PubMed

Multivariate spectrophotometric calibration and liquid chromatographic (LC) methods were applied to the determination of 2 multicomponent mixtures containing diprophylline, guaiphenesin, methylparaben, and propylparaben (Mixture 1), or clobutinol, orciprenaline, saccharin sodium, and sodium benzoate (Mixture 2). For the multivariate spectrophotometric calibration methods, principal component regression (PCR) and partial least-squares regression (PLS-1), a calibration set of the mixtures consisting of the components of each mixture was prepared in 0.1 M HCl. Analytical figures of merit such as sensitivity, selectivity, limit of quantitation, and limit of detection were determined for both PLS-1 and PCR. The LC separation was achieved on a reversed-phase C18 analytical column by using isocratic elution with 20 mM potassium dihydrogen phosphate, pH 3.3-acetonitrile (55 + 45, v/v) as the mobile phase and UV detection at 260 and 220 nm for Mixture 1 and Mixture 2, respectively. The proposed methods were validated and successfully applied to the analysis of pharmaceutical formulations and laboratory-prepared mixtures containing the 2 multicomponent combinations. PMID:18376584

Hadad, Ghada M; El-Gindy, Alaa; Mahmoud, Waleed M M

2008-01-01

223

Development of a Rapid Derivative Spectrophotometric Method for Simultaneous Determination of Acetaminophen, Diphenhydramine and Pseudoephedrine in Tablets  

PubMed Central

A mixture of acetaminophen, diphenhydramine hydrochloride and pseudoephedrine hydrochloride is used for the symptomatic treatment of common cold. In this study, a derivative spectrophotometric method based on zero-crossing technique was proposed for simultaneous determination of acetaminophen, diphenhydramine hydrochloride and pseudoephedrine hydrochloride. Determination of these drugs was performed using the 1D value of acetaminophen at 281.5 nm, 2D value of diphenhydramine hydrochloride at 226.0 nm and 4D value of pseudoephedrine hydrochloride at 218.0 nm. The analysis method was linear over the range of 5-50, 0.25-4, and 0.5-5 µg/mL for acetaminophen, diphenhydramine hydrochloride and pseudoephedrine hydrochloride, respectively. The within-day and between-day CV and error values for all three compounds were within an acceptable range (CV<2.2% and error<3%). The developed method was used for simultaneous determination of these drugs in pharmaceutical dosage forms and no interference from excipients was observed.

Souri, Effat; Rahimi, Aghil; Shabani Ravari, Nazanin; Barazandeh Tehrani, Maliheh

2015-01-01

224

In situ spectrophotometric determination of pH under geologic CO2 sequestration conditions: method development and application.  

PubMed

CO(2) injection into deep geologic formations for long-term storage will cause a decrease in aqueous pH due to CO(2) dissolution into reservoir water/brine. Current studies seeking to assess chemical changes under geological CO(2) sequestration (GCS) conditions rely largely on thermodynamic modeling due to the lack of reliable experimental methods. In this work, a spectrophotometric method utilizing bromophenol blue to measure pH in laboratory experiments under GCS-relevant conditions was developed. The method was tested in simulated reservoir fluids (CO(2)-NaCl-H(2)O) at different temperatures, pressures, and ionic strengths, and the results were compared with those from other experimental studies and geochemical models. Measured pH values were generally in agreement with the models, but inconsistencies were present between the models. In situ pH measurements for a basalt rock-CO(2)-brine system were conducted under GCS conditions. The pH increased to 3.52 during a 10-day period due to rock dissolution, compared to pH 2.95 for the CO(2)-brine system without rock. The calculated pH values from geochemical models were 0.22-0.25 units higher than the measured values (assuming all iron in the system was in the form of Fe(2+)). This work demonstrates the use of in situ spectrophotometry for pH measurement under GCS-relevant conditions. PMID:22708540

Shao, Hongbo; Thompson, Christopher J; Qafoku, Odeta; Cantrell, Kirk J

2013-01-01

225

A new spectrophotometric method for the determination of total and ferric iron in rain water at the ppb level.  

PubMed

A new, simple, selective and sensitive spectrophotometric procedure for the on-site quantification of iron at nano-gram levels in atmospheric precipitations, i.e. rain as sample source is described. It is based on the color reaction of Fe3+ with SCN- ions in the presence of a cationic surfactant, i.e. cetylpyridinium chloride (CPC), in strong HCl solution, and subsequent extraction of the complex with N-octylacetamide into toluene or chloroform. The apparent molar absorptivity of the complex is 2.60 x 10(5) L mol(-1) cm(-1) at lambdamax = 480 nm at an enrichment factor (EF) of 10. The detection limit (causing higher absorbance than the sum of the blank absorbance (0.009) and 3 SD) is 5 ng mL(-1) Fe. Ions commonly associated with iron did not interfere in the present method. The effect of analytical variables, i.e. amount and type of the reagents, acidity, solvent, temperature, dilution, etc., in the determination of iron are discussed. The validity of the present method is checked with GF-AAS. The method has been applied to the determination of iron at the ppb level in rain water samples. PMID:11336339

Patel, K S; Shukla, A; Goswami, A; Chandavanshi, S K; Hoffmann, P

2001-03-01

226

Spectrophotometric probe  

DOEpatents

A support structure is described bearing at least one probe for making spectrophotometric measurements of a fluid using a source of light and a spectrophotometer. The probe includes a housing with two optical fibers and a planoconvex lens. A sleeve bearing a mirror surrounds the housing. The lens is separated from the mirror by a fixed distance, defining an interior space for receiving a volume of the fluid sample. A plurality of throughholes extending through the sleeve communicate between the sample volume and the exterior of the probe, all but one hole bearing a screen. A protective jacket surrounds the probe. A hollow conduit bearing a tube is formed in the wall of the probe for venting any air in the interior space when fluid enters. The probe is held at an acute angle so the optic fibers carrying the light to and from the probe are not bent severely on emergence from the probe. 3 figs.

Prather, W.S.; O'Rourke, P.E.

1994-08-02

227

Spectrophotometric probe  

DOEpatents

A support structure bearing at least one probe for making spectrophotometric measurements of a fluid using a source of light and a spectrophotometer. The probe includes a housing with two optical fibers and a planoconvex lens. A sleeve bearing a mirror surrounds the housing. The lens is separated from the mirror by a fixed distance, defining an interior space for receiving a volume of the fluid sample. A plurality of throughholes extending through the sleeve communicate between the sample volume and the exterior of the probe, all but one hole bearing a screen. A protective jacket surrounds the probe. A hollow conduit bearing a tube is formed in the wall of the probe for venting any air in the interior space when fluid enters. The probe is held at an acute angle so the optic fibers carrying the light to and from the probe are not bent severely on emergence from the probe.

Prather, William S. (Augusta, GA); O'Rourke, Patrick E. (Martinez, GA)

1994-01-01

228

Comparative study of three modified numerical spectrophotometric methods: An application on pharmaceutical ternary mixture of aspirin, atorvastatin and clopedogrel  

NASA Astrophysics Data System (ADS)

Three novel numerical methods were developed for the spectrophotometric multi-component analysis of capsules and synthetic mixtures of aspirin, atorvastatin and clopedogrel without any chemical separation. The subtraction method is based on the relationship between the difference in absorbance at four wavelengths and corresponding concentration of analyte. In this method, the linear determination ranges were 0.8-40 ?g mL-1 aspirin, 0.8-30 ?g mL-1 atorvastatin and 0.5-30 ?g mL-1 clopedogrel. In the quotient method, 0.8-40 ?g mL-1 aspirin, 0.8-30 ?g mL-1 atorvastatin and 1.0-30 ?g mL-1 clopedogrel were determine from spectral data at the wavelength pairs that show the same ratio of absorbance for other two species. Standard addition method was used for resolving ternary mixture of 1.0-40 ?g mL-1 aspirin, 0.8-30 ?g mL-1 atorvastatin and 2.0-30 ?g mL-1 clopedogrel. The proposed methods were validated. The reproducibility and repeatability were found satisfactory which evidence was by low values of relative standard deviation (<2%). Recovery was found to be in the range (99.6-100.8%). By adopting these methods, the time taken for analysis was reduced as these methods involve very limited steps. The developed methods were applied for simultaneous analysis of aspirin, atorvastatin and clopedogrel in capsule dosage forms and results were in good concordance with alternative liquid chromatography.

Issa, Mahmoud Mohamed; Nejem, R.'afat Mahmoud; Shanab, Alaa Abu; Hegazy, Nahed Diab; Stefan-van Staden, Raluca-Ioana

2014-07-01

229

Spectrophotometric methods based on 2,6-dichloroindophenol acetate and indoxylacetate for butyrylcholinesterase activity assay in plasma.  

PubMed

Butyrylcholinesterase (BChE) is an enzyme presented in quite high level in blood plasma where it participates in detoxification reactions. Due to fact that the enzyme is constituted in livers, it is a marker of liver parenchyma function. It can be used for diagnosis of poisoning for e.g., nerve agents or carbofuran and intoxication by some drugs such as rivastigmine. The present experiment is devoted for the creation of new spectrophotometric tests for assay of BChE activity in biological samples. Standard Ellman's method was compared with use of 2,6-dichloroindophenol acetate and indoxylacetate as chromogenic substrates. Maximal velocities and Michaelis constants were calculated for the substrates. Considering calibration, 2,6-dichloroindophenol acetate provided the lowest limit of detection: 1.20 × 10(-9)kat and a long linear range. All methods were verified using pooled human plasma samples and tested for potential interferents. 2,6-dichloroindophenol acetate is recommended as suitable substrate for BChE assay in clinical diagnostics. PMID:23598128

Pohanka, Miroslav; Drtinova, Lucie

2013-03-15

230

Sensitive spectrofluorimetric and spectrophotometric methods for the determination of thonzylamine hydrochloride in pharmaceutical preparations based on coupling with dimethylbarbituric acid in presence of dicyclohexylcarbodiimide  

Microsoft Academic Search

Two sensitive and selective spectrophotometric and spectrofluoimetric procedures were developed for the determination of thonzylamine hydrochloride (THAH) in tablets and nasal drops. The methods are based on König reaction which resulted in an orange-yellow fluorescent product. The orange-yellow product of the interaction between the dicyclohexylcarbodiimide (DCC), THAH and dimethylbarbituric acid (DMBA) showed an absorption maximum at 492 nm, a first-derivative

Suzy M Sabry; Mohamed H Abdel-Hay; Magda H Barary; Tarek S Belal

2000-01-01

231

Accelerated UV Test Methods for Encapsulants of Photovoltaic Modules: Preprint  

SciTech Connect

This paper asserts that materials used for PV encapsulation must be evaluated for their ability to transmit light and to maintain mechanical integrity for extended periods of time under long term UV exposure.

Kempe, M. D.

2008-05-01

232

H-Point Standard Addition Method (HPSAM) in Simultaneous Spectrophotometric Determination of Binary Mixtures: An Overview  

Microsoft Academic Search

The H-point standard addition method (HPSAM) is a modification of the standard addition method that transforms the incorrigible error resulting from the presence of a direct interferent in the determination of an analyte into a constant systematic error. This error can then be evaluated and eliminated. The method was established for resolving strongly overlapping spectra of two analytes and permits

Theia’a N. Al-Sabha; Andrei A. Bunaciu; Hassan Y. Aboul-Enein

2011-01-01

233

Determination of phosphorus in food samples by X-ray fluorescence spectrometry and standard spectrophotometric method  

Microsoft Academic Search

The Wavelength Dispersive X-ray fluorescence (WD XRF) determination of phosphorus in GMO and non GMO food samples is proposed. The tested materials included commercially available transgenic, unmodified soya-foods and popular dairy products. The WD XRF method was compared with the standard molybdenum blue method. Matrix effects were minimised by using standard reference material. Obtained results were discussed in respect of

A Jastrz?bska; B Brudka; T Szyma?ski; E Sz?yk

2003-01-01

234

Spectrophotometric methods for the determination of omeprazole in bulk form and pharmaceutical formulations.  

PubMed

Four simple and sensitive methods for the assay of omeprazole (OMZ) were developed. These methods are based on the formation of colored species by treating OMZ with 3-methyl-2-benzothiazolinone hydrazone (MBTH) following oxidation with ferric chloride (method A) or m-aminophenol following oxidation with chloramine-T (CAT) (method B) or Folin-Ciocalteau reagent (FC) (method D), or by oxidizing OMZ with excess N-bromosuccinimide (NBS) and determining the consumed NBS with a decrease in color intensity of Celestine blue (CB) (method C). All variables have been optimized. Regression analysis of Beer's plots showed good correlation in the concentration range of 1.0-10, 2.0-32, 0.4-2.4 and 0.8-10 mug ml(-1) for methods A, B, C and D, respectively. No interference was observed for formulation additives and the validity of each method was tested by analysing capsules containing OMZ. Recoveries were 98.7-100.1%. PMID:18966856

Sastry, C S; Naidu, P Y; Murty, S S

1997-07-01

235

A new spectrophotometric method for the determination of finasteride in tablets  

Microsoft Academic Search

A simple, rapid, accurate, precise and sensitive colorimetric method for the determination of finasteride in tablets is described. The proposed methods are based on the formation of ion-pair complexes between the examined drug with bromophenol blue (BPB), bromocresol green (BCG) and bromothymol blue (BTB), which can be measured at the optimum ?max. Beer's law is obeyed in the concentration ranges

Sevgi Tatar Ulu

2007-01-01

236

A simple kinetic spectrophotometric method for the determination of isoxsuprine in dosage forms  

Microsoft Academic Search

A simple and sensitive kinetic method was developed for the determination of isoxsuprine in pharmaceutical preparations. The method is based upon a kinetic investigation of the oxidation reaction of the drug with alkaline potassium permanganate at room temperature for a fixed time of 30 min. The absorbance of the coloured manganate ion was measured at 610 nm. Alternatively, the decrease

N. El-Enany; F. Belal; M. Rizk

2002-01-01

237

Spectrophotometric stability-indicating methods for the determination of leflunomide in the presence of its degradates.  

PubMed

Five simple and sensitive methods were developed for the determination of leflunomide (I) in the presence of its degradates 4-trifluoromethyl aniline (II) and 3-methyl-4-carboxy isoxazole (III). Method A was based on differential derivative spectrophotometry by measuring the delta(1)D value at 279.5 nm. Beer's law was obeyed in the concentration range of 2.00-20.00 microg/mL with mean percentage accuracy of 100.07 +/- 1.32. Method B depended on first-derivative spectrophotometry and measuring the amplitude at 253.4 nm. Beer's law was obeyed in the concentration range of 2.00-16.00 microg/mL with mean percentage accuracy of 98.42 +/- 1.61. Method C was based on the reaction of degradate (II) with 2,6-dichloroquinone-4-chloroimide (Gibbs reagent). The colored product was measured at 469 nm. Method D depended on the reaction of degradate (II) with para-dimethyl aminocinnamaldehyde (p-DAC). The absorbance of the colored product was measured at 533.4 nm. Method E utilized 3-methyl-2-benzothiazolinone hydrazone in the presence of cerric ammonium sulfate with degradate (II). The green colored product was measured at 605.5 nm. The linearity range was 40.00-280.00, 2.40-24.00, and 30-250 microg/mL with mean percentage accuracy of 100.75 +/- 1.21, 100.13 +/- 1.45, and 99.74 +/- 1.39 for Methods C-E, respectively. All variables were studied to optimize the reaction conditions. The proposed methods have been successfully applied to the analysis of leflunomide in pharmaceutical dosage forms and the results were statistically compared with that previously reported. PMID:17225597

Abbas, Samah S; Bebawy, Lories I; Fattah, Laila A; Refaat, Heba H

2006-01-01

238

Novel spectrophotometric determination of chloramphenicol and dexamethasone in the presence of non labeled interfering substances using univariate methods and multivariate regression model updating.  

PubMed

Smart and novel spectrophotometric and chemometric methods have been developed and validated for the simultaneous determination of a binary mixture of chloramphenicol (CPL) and dexamethasone sodium phosphate (DSP) in presence of interfering substances without prior separation. The first method depends upon derivative subtraction coupled with constant multiplication. The second one is ratio difference method at optimum wavelengths which were selected after applying derivative transformation method via multiplying by a decoding spectrum in order to cancel the contribution of non labeled interfering substances. The third method relies on partial least squares with regression model updating. They are so simple that they do not require any preliminary separation steps. Accuracy, precision and linearity ranges of these methods were determined. Moreover, specificity was assessed by analyzing synthetic mixtures of both drugs. The proposed methods were successfully applied for analysis of both drugs in their pharmaceutical formulation. The obtained results have been statistically compared to that of an official spectrophotometric method to give a conclusion that there is no significant difference between the proposed methods and the official ones with respect to accuracy and precision. PMID:25659506

Hegazy, Maha A; Lotfy, Hayam M; Rezk, Mamdouh R; Omran, Yasmin Rostom

2015-04-01

239

Four Derivative Spectrophotometric Methods for the Simultaneous Determination of Carmoisine and Ponceau 4R in Drinks and Comparison with High Performance Liquid Chromatography  

PubMed Central

Four simple, rapid, and accurate spectrophotometric methods were developed for the simultaneous determination of two food colorants, Carmoisine (E122) and Ponceau 4R (E124), in their binary mixtures and soft drinks. The first method is based on recording the first derivative curves and determining each component using the zero-crossing technique. The second method uses the first derivative of ratio spectra. The ratio spectra are obtained by dividing the absorption spectra of the binary mixture by that of one of the components. The third method, derivative differential procedure, is based on the measurement of difference absorptivities derivatized in first order of solution of drink samples in 0,1?N NaOH relative to that of an equimolar solution in 0,1?N HCl at wavelengths of 366 and 451?nm for Carmoisine and Ponceau 4R, respectively. The last method, based on the compensation method is presented for derivative spectrophotometric determination of E122 and E124 mixtures with overlapping spectra. By using ratios of the derivative maxima, the exact compensation of either component in the mixture can be achieved, followed by its determination. These proposed methods have been successfully applied to the binary mixtures and soft drinks and the results were statistically compared with the reference HPLC method (NMKL 130). PMID:24672549

Turak, Fatma; Dinç, Mithat; Dülger, Öznur; Özgür, Mahmure Ustun

2014-01-01

240

Standardization and Application of Spectrophotometric Method for Reductive Capacity Measurement of Nanomaterials  

E-print Network

method had been lacking until this work. The reductive capacity of nanoparticles was defined as the mass of iron reduced from Fe3 to Fe 2 by unit mass of nanoparticles, in an aqueous solution that initially contained ferric ions. To measure the reductive...

Hwang, Wonjoong

2011-10-21

241

Kinetic Spectrophotometric Method for The Determination of Ketoprofen in Pharmaceuticals and Biological Fluids  

PubMed Central

A simple and sensitive kinetic method is described for the determination of ketoprofen in pure form, pharmaceuticals and biological fluids. The method utilizes an oxidative- coupling reaction based upon oxidation of 3-methyl-2-benzo-thiazolinone hydrazone hydrochloride (MBTH) with Ce(IV) in presence of HCl, where an electrophilic intermediate (diazonium salt of the reagent) is produced, then couples with ketoprofen yielding a highly colored condensation product. The absorbance is measured after 20 min at 605 nm. Calibration graph was linear over the concentration range of 1-8?g/mL with a minimum detection limit of 0.07 ?g/mL. The proposed method was applied successfully to the determination of Ketoprofen in pharmaceutical preparations, plasma and urine. The % recoveries were 100.11 for pure form, 100.10 for tablets and gel, 100.0 for suspension and suppositories, 100.2 for capsules and ampoules and 99.79, 99.9 for plasma and urine. The results obtained were in good agreement with those obtained using reference methods for comparison. PMID:23675009

El-Brashy, A.; Eid, M.; Talaat, W.

2006-01-01

242

A simple kinetic spectrophotometric method for the determination of oxamniquine in formulations and spiked biological fluids  

Microsoft Academic Search

A simple and sensitive kinetic method for the determination of oxamniquine in pharmaceutical preparations and biological fluids was developed. The procedure is based upon a kinetic investigation of the oxidation reaction of the drug with alkaline potassium permanganate at room temperature for a fixed time of 20 min. The absorbance of the colored manganate ions was measured at 610 nm.

M. Rizk; F. Belal; F. Ibrahim; S. M. Ahmed; N. M. El-Enany

2000-01-01

243

Indirect method for spectrophotometric determination of ascorbic acid in pharmaceutical preparations with 2,4,6-tripyridyl-s-triazine by flow-injection analysis  

Microsoft Academic Search

A flow-injection indirect spectrophotometric method for the determination of ascorbic acid (AA) in pharmaceutical preparations is proposed. The method is based on the reduction of iron(III) to iron(II) by the AA, and by the subsequent reaction of the produced iron(II) with 2,4,6-tripyridyl-s-triazine (TPTZ) in buffered medium (pH=3.6) to form a coloured complex (?max=593nm). The three-line manifold with one reaction coil

Lea Kukoc-Modun; Maja Biocic; Njegomir Radi?

244

Measured UV spectra compared with discrete ordinate method simulations  

SciTech Connect

A comprehensive radiative transfer model is used to calculate surface spectral ultraviolet irradiance under cloud-free conditions. The results are compared with measurements made at Lauder, New Zealand (45 deg S, 170 deg E) before and after the eruption of Mount Pinatubo and including a snow-covered surface. There is reasonable agreement between measured and calculated diffuse, direct, and global irradiances over the range 300 to 450 nm. Discrepancies may be due to calibration errors in the UV measurements, or in the extra terrestrial irradiances input to the model. Ratios of diffuse/direct irradiances are independent of such calibration uncertainties and therefore provide a sensitive test of the model. If appropriate ozonesonde data, surface albedo, and aerosol optical properties are used, the model ratios are in satisfactory agreement with measurements over a wide range of observing conditions. For cases in which the atmospheric optical properties are best known the agreement is better than 8% in the UV-B range, and for wavelengths 320 to 450 nm the deviation is smaller. The comparison suggests that the ultraviolet radiation exposure can be computed with confidence for clear sky conditions if the appropriate atmospheric molecular density profiles, ozonesonde data, surface albedo, and aerosol optical properties are available. The UV radiation model is used to investigate the impact of changes in solar zenith angle, ozone abundance, surface albedo, and aerosol loading on UV radiation reaching the surface of the Earth. The ratios of diffuse to direct irradiance depend critically on solar zenith angle, surface albedo, and aerosol extinction. Ozone changes have pronounced effects on the global UVB irradiance but have only a minor effect on these ratios.

Zeng, J.; Mckenzie, R.; Stamnes, K.; Wineland, M.; Rosen, J. [Univ. of Alaska, Fairbanks, AK (United States)]|[Univ. of Wyoming, Laramie, WY (United States)

1994-11-01

245

Ion-association method for the spectrophotometric determination of the antitussive drug noscapine  

Microsoft Academic Search

A simple, sensitive and fairly rapid method for the determination of noscapine is described, based on the measurement of the absorbance of the organic soluble ion-association complex formed between the noscapine monocation and a bulky counter anion. Methyl Orange, Bromothymol Blue and Bromocresol Green (BCG) were examined as counter ions. The effect of few solvents, the counter-ion concentration and pH

Bahruddin Saad; Salah M. Sultan; Fakhr Eldin O. Suliman

1997-01-01

246

The Spectrophotometric Method of Determining the Transmission of Solar Energy in Salt Gradient Solar Ponds  

NASA Technical Reports Server (NTRS)

In order to predict the thermal efficiency of a solar pond it is necessary to know total average solar energy reaching the storage layer. One method for determining this energy for water containing dissolved colored species is based upon spectral transmission measurements using a laboratory spectrophotometer. This method is examined and some of the theoretical ground work needed to discuss the measurement of transmission of light water. Results of in situ irradiance measurements from oceanography research are presented and the difficulties inherent in extrapolating laboratory data obtained with ten centimeter cells to real three dimensional pond situations is discussed. Particular emphasis is put on the need to account for molecular and particulate scattering in measurements done on low absorbing solutions. Despite these considerations it is expected that attenuation calculations based upon careful measurements using a dual beam spectrophotometer technique combined with known attenuation coefficients will be useful in solar pond modeling and monitoring for color buildup. Preliminary results using the CSM method are presented.

Giulianelli, J.

1984-01-01

247

Speciation determination of chromium using 1,4-diaminoanthraquinone with spectrophotometric and spectrofluorometric methods.  

PubMed

A highly sensitive and selective method has been proposed for speciation determination of trace amounts of Cr(III) and Cr(VI) in water samples using 1,4-diaminoanthraquinone (1,4-DAAQ). The method is based on mixing an organic phase containing 1,4-DAAQ with an acidic solution (pH 1) of Cr(VI), which is accomplished with absorbance decreasing or luminescence quenching of the organic phase due to a partial oxidation of the 1,4-DAAQ content. After oxidation of Cr(III) to Cr(VI) and determining the total chromium content, Cr(III) content is obtained by subtracting. All of the variables were studied in order to optimize the reaction conditions. No considerable interference was observed due to the presence of coexisting anions and cations. The calibration graphs were linear in the range 3.0 x 10(-7)-3.0 x 10(-6) and 1.0 x 10(-7)-4.0 x 10(-6) M with detection limits of 3.5 x 10(-8) and 2.1 x 10(-9) M for absorptiometry and fluorometry, respectively. Validation of the measurements was confirmed using standard reference materials and a certificated method. PMID:19531892

Hosseini, Mohammad Saeid; Asadi, Mohammad

2009-06-01

248

Quantitative analysis of extracted phycobilin pigments in cyanobacteria-an assessment of spectrophotometric and spectrofluorometric methods.  

PubMed

Phycobilins are an important group of pigments that through complementary chromatic adaptation optimize the light-harvesting process in phytoplankton cells, exhibiting great potential as cyanobacteria species biomarkers. In their extracted form, concentrations of these water-soluble molecules are not easily determined using the chromatographic methods well suited to solvent-soluble pigments. Insights regarding the quantitative spectroscopic analysis of extracted phycobilins also remain limited. Here, we present an in-depth study of two methods that utilize the spectral properties of phycobilins in aqueous extracts. The technical work was carried out using high-purity standards of phycocyanin, phycoerythrin, and allophycocyanin. Calibration parameters for the spectrofluorometer and spectrophotometer were established. This analysis indicated the possibility of detecting pigments in concentrations ranging from 0.001 to 10 ?g cm(-3). Fluorescence data revealed a reproducibility of 95 %. The differences in detection limits between the two methods enable the presence of phycobilins to be investigated and their amounts to be monitored from oligotrophic to eutrophic aquatic environments. PMID:25346572

Sobiechowska-Sasim, Monika; Sto?-Egiert, Joanna; Kosakowska, Alicja

2014-01-01

249

Field Application of a Rapid Spectrophotometric Method for Determination of Persulfate in Soil  

E-print Network

Remediation of hydrocarbon contaminated soils can be performed both in situ and ex situ using chemical oxidants such as sodium persulfate. Standard methods for quantifying persulfate require either centrifugation or prolonged settling times. An optimized soil extraction procedure was developed for persulfate involving simple water extraction using a modified disposable syringe. This allows considerable saving of time and removes the need for centrifugation. The extraction time was reduced to only 5 min compared to 15 min for the standard approach. A comparison of the two approaches demonstrated that each provides comparable results. Comparisons were made using high (93 g kg 21 soil) and low (9.3 g kg 21 soil) additions of sodium persulfate to a petroleum hydrocarbon-contaminated soil, as well as sand spiked with diesel. Recoveries of 9561 % and 96610 % were observed with the higher application rate in the contaminated soil and spiked sand, respectively. Corresponding recoveries of 8665 % and 117619 % were measured for the lower application rate. Results were obtained in only 25 min and the method is well suited to batch analyses. In addition, it is suitable for application in a small field laboratory or even a mobile, vehicle-based system, as it requires minimal equipment and reagents.

Colin J. Cunningham; Vanessa Pitschi; Peter Anderson; D. A. Barry; Colin Patterson; Tanya A. Peshkur

2013-01-01

250

Field Application of a Rapid Spectrophotometric Method for Determination of Persulfate in Soil  

PubMed Central

Remediation of hydrocarbon contaminated soils can be performed both in situ and ex situ using chemical oxidants such as sodium persulfate. Standard methods for quantifying persulfate require either centrifugation or prolonged settling times. An optimized soil extraction procedure was developed for persulfate involving simple water extraction using a modified disposable syringe. This allows considerable saving of time and removes the need for centrifugation. The extraction time was reduced to only 5 min compared to 15 min for the standard approach. A comparison of the two approaches demonstrated that each provides comparable results. Comparisons were made using high (93 g kg?1 soil) and low (9.3 g kg?1 soil) additions of sodium persulfate to a petroleum hydrocarbon-contaminated soil, as well as sand spiked with diesel. Recoveries of 95±1% and 96±10% were observed with the higher application rate in the contaminated soil and spiked sand, respectively. Corresponding recoveries of 86±5% and 117±19% were measured for the lower application rate. Results were obtained in only 25 min and the method is well suited to batch analyses. In addition, it is suitable for application in a small field laboratory or even a mobile, vehicle-based system, as it requires minimal equipment and reagents. PMID:23776446

Cunningham, Colin J.; Pitschi, Vanessa; Anderson, Peter; Barry, D. A.; Patterson, Colin; Peshkur, Tanya A.

2013-01-01

251

A comparative study between three stability indicating spectrophotometric methods for the determination of diatrizoate sodium in presence of its cytotoxic degradation product based on two-wavelength selection.  

PubMed

Three sensitive, selective, and precise stability indicating spectrophotometric methods for the determination of the X-ray contrast agent, diatrizoate sodium (DTA) in the presence of its acidic degradation product (highly cytotoxic 3,5-diamino metabolite) and in pharmaceutical formulation, were developed and validated. The first method is ratio difference, the second one is the bivariate method, and the third one is the dual wavelength method. The calibration curves for the three proposed methods are linear over a concentration range of 2-24?g/mL. The selectivity of the proposed methods was tested using laboratory prepared mixtures. The proposed methods have been successfully applied to the analysis of DTA in pharmaceutical dosage forms without interference from other dosage form additives. The results were statistically compared with the official US pharmacopeial method. No significant difference for either accuracy or precision was observed. PMID:25791882

Riad, Safaa M; El-Rahman, Mohamed K Abd; Fawaz, Esraa M; Shehata, Mostafa A

2015-06-15

252

A study of selective spectrophotometric methods for simultaneous determination of Itopride hydrochloride and Rabeprazole sodium binary mixture: Resolving sever overlapping spectra.  

PubMed

Itopride hydrochloride (IT) and Rabeprazole sodium (RB) are co-formulated together for the treatment of gastro-esophageal reflux disease. Three simple, specific and accurate spectrophotometric methods were applied and validated for simultaneous determination of Itopride hydrochloride (IT) and Rabeprazole sodium (RB) namely; constant center (CC), ratio difference (RD) and mean centering of ratio spectra (MCR) spectrophotometric methods. Linear correlations were obtained in range of 10-110?g/?L for Itopride hydrochloride and 4-44?g/mL for Rabeprazole sodium. No preliminary separation steps were required prior the analysis of the two drugs using the proposed methods. Specificity was investigated by analyzing the synthetic mixtures containing the two cited drugs and their capsules dosage form. The obtained results were statistically compared with those obtained by the reported method, no significant difference was obtained with respect to accuracy and precision. The three methods were validated in accordance with ICH guidelines and can be used for quality control laboratories for IT and RB. PMID:25456673

Mohamed, Heba M

2014-10-28

253

[Determination of chemical oxygen demand in water using near infrared transmission and UV absorbance method].  

PubMed

Chemical oxygen demand (COD) is a synthetical indicator which represents the degree of organic pollution in water. The near-infrared (NIR) transmission and the UV absorbance method based on photoelectric detection technology and spectroscopy analysis have some advantages such as high precision, speed, non-contact, no secondary pollution etc compared to conventional wet chemical method. The NIR transmission spectra and UV absorbance spectra of standard solution configured with phthalate hydrogen potassium were collected respectively by MPA FTIR spectrometer (Bruker Optics Inc.) made in Germany and AvaSpec-2048-2 UV spectrometer (Avantes Inc.) made in Netherlands. After different pretreatment to the spectra, COD quantitative analysis model was established using partial least squares regression (PLS) and linear regression. The statistical analysis of COD quantitative model was implemented, and the result showed that UV absorbance method had a higher relevance but lower forecast accuracy and precision than NIR transmission method. PMID:21847915

Wu, Guo-Qing; Bi, Wei-Hong; Lui, Jia-Ming; Fu, Guang-Wei

2011-06-01

254

A simple photolithography method for microfluidic device fabrication using sunlight as UV source  

Microsoft Academic Search

A straightforward method for microfluidic devices fabrication using sunlight as the ultraviolet (UV) source is established\\u000a in this work. This method is based on photolithography, but obviates the need for specialized UV exposure facility. Substrates\\u000a coated with photoresist were placed directly under sun in a perpendicular direction to the sunlight for exposure. Exposure\\u000a conditions were optimized for patterning features with

Jingyun MaLei; Lei Jiang; Xiaoyan Pan; Huipeng Ma; Bingcheng Lin; Jianhua Qin

2010-01-01

255

Spectrophotometric Determination of Iron(II) and Cobalt(II) by Direct, Derivative, and Simultaneous Methods Using 2-Hydroxy-1-Naphthaldehyde-p-Hydroxybenzoichydrazone  

PubMed Central

Optimized and validated spectrophotometric methods have been proposed for the determination of iron and cobalt individually and simultaneously. 2-hydroxy-1-naphthaldehyde-p-hydroxybenzoichydrazone (HNAHBH) reacts with iron(II) and cobalt(II) to form reddish-brown and yellow-coloured [Fe(II)-HNAHBH] and [Co(II)-HNAHBH] complexes, respectively. The maximum absorbance of these complexes was found at 405?nm and 425?nm, respectively. For [Fe(II)-HNAHBH], Beer's law is obeyed over the concentration range of 0.055–1.373??g?mL?1 with a detection limit of 0.095??g?mL?1 and molar absorptivity ?, 5.6 × 104?L mol?1 cm?1. [Co(II)-HNAHBH] complex obeys Beer's law in 0.118–3.534??g?mL?1 range with a detection limit of 0.04??g?mL?1 and molar absorptivity, ? of 2.3 × 104?L mol?1 cm?1. Highly sensitive and selective first-, second- and third-order derivative methods are described for the determination of iron and cobalt. A simultaneous second-order derivative spectrophotometric method is proposed for the determination of these metals. All the proposed methods are successfully employed in the analysis of various biological, water, and alloy samples for the determination of iron and cobalt content. PMID:22505925

Devi, V. S. Anusuya; Reddy, V. Krishna

2012-01-01

256

Improved methods for adjusting the UV content of measurement instrument illumination for papermaking industry  

NASA Astrophysics Data System (ADS)

Optical brightening agents (OBAs) or fluorescent whitening agents (FWAs) are often used additives in paper and board products as they improve both whiteness and brightness of the products. When printed, OBAs can even contribute to colour tone reproduction. Fluorescent emissions of OBAs depend on the UV content of the illuminant (light source). Adequate adjustment (control or adjustment) of UV content of measurement apparatus (e.g. spectrophotometer) is essential for accurate colour measurement and printing colour reproduction. We proposed a method to adjust the UV content against assigned spectra rather than, as adopted in current ISO standards, against single assigned values. Demonstrations of applying this method to the CIE standard illuminants used in papermaking and graphic industries, D65, C and D50 have been given. Thanks to the well-established traceability of reference standards (IRs), the UV contents of a spectrophotometer corresponding to the standard CIE illuminants have been achieved.

Yang, Li

2014-09-01

257

Method Development and Validation of a Rapid Determination of Ropinirole in Tablets by LC-UV  

Microsoft Academic Search

A reversed-phase high-performance liquid chromatographic (HPLC) method with UV detection was developed and validated for the determination of ropinirole (ROP) in tablets. The assay utilized UV detection at 250 nm and a Luna CN column (250  4.6 mm I.D, 5 ?m). The mobile phases were comprised of acetonitrile: 10 mM nitric acid (pH 3.0) (75:25, v\\/v). Validation experiments were performed to demonstrate linearity, accuracy, precision,

A. Önal

2006-01-01

258

Trailed Spectra of Bright Spectrophotometric Standard Stars  

NASA Astrophysics Data System (ADS)

The IUE archives is an extensive and growing database of UV spectra of a wide variety of astronomical objects. The usefulness of the archives will be greatly enhanced by the presence of a number of wellobserved standard stars including those which define the visual wavelength absolute flux calibrations. Observation of ground-based spectrophotometric standards by IUE will be useful for providing a selfconsistent flux calibration for bright stars and for permitting direct comparisons with fainter standards for future missions, already in the archives, on the IUE system. New observing techniques now make it possible for IUE to obtain well-exposed spectra of these bright stars. However, this observing method is one of the few which may not be possible if IUE were to lose another gyro and the backup control mode, now under development, were used. We propose to obtain short and long wavelength spectra for four of the brightest spectrophotometric standard stars which have either not been observed with with IUE or are poorly represented in the IUE archives. Over a number of years these stars have been observed and defined as standards by a number of ground based observers including Oke(1964), Breger (1976), Stone(1977), Oke and Gunn (1983), and Taylor (1984). The primary standard has been Vega with 109 Vir as an alternate (Davis Philip and Hayes 1984). By combining trailed and point source spectra, ultraviolet absolute flux distributions will be obtained for the 1200-3200 A interval. A comparison will be made of Alpha Lyr and 109 Vir with the nearby star Alpha CMA A, which has a well-determined distance and measured radius. The suspected low-level intermittent variability of Alpha Lyr is not believed to pose major problems for our analysis.

Pitts, Ronald E.

259

Using spectrophotometric titrations to characterize humic acid reactivity at environmental concentrations.  

PubMed

Potentiometric titration is a common method to characterize dissolved organic matter (DOM) reactivity. Because of the sensitivity of pH electrodes, it is necessary to work with very high DOM (>1 g/L) concentrations that are unrealistic compared to those found in natural waters (0.1 to 100 mg/L). To obtain proton binding data for concentrations closer to environmental values, spectroscopic titration methodology is a viable alternative to traditional potentiometric titrations. Spectrophotometric titrations and UV-visible spectra of a diluted solution of purified Aldrich humic acid (5 mgDOC/L) are used to estimate changes in proton binding moieties as function of pH and ionic strength after calculation of differential absorbance spectra variations. After electrostatic correction of spectrophotometric data, there is a linear operational correlation between spectrophotometric and potentiometric data which can be used as a transfer function between the two properties. Spectrophotometric titrations are then used to determine the changes of humic acid protonation after adsorption onto alpha-alumina. PMID:20698549

Janot, Noémie; Reiller, Pascal E; Korshin, Gregory V; Benedetti, Marc F

2010-09-01

260

Development and validation of a rapid stability indicating HPLC-method using monolithic stationary phase and two spectrophotometric methods for determination of antihistaminic acrivastine in capsules  

NASA Astrophysics Data System (ADS)

Simple, rapid and accurate high performance liquid chromatographic (HPLC) and spectrophotometric methods are described for determination of antihistaminic acrivastine in capsules. The first method (method A) is based on accurate, sensitive and stability indicating chromatographic separation method. Chromolith® Performance RP-18e column, a relatively new packing material consisting of monolithic rods of highly porous silica, was used as stationary phase applying isocratic binary mobile phase of ACN and 25 mM NaH2PO4 pH 4.0 in the ratio of 22.5:77.5 at flow rate of 5.0 mL/min and 40 °C. A diode array detector was used at 254 nm for detection. The elution time of acrivastine was found to be 2.080 ± 0.032. The second and third methods (methods B and C) are based on the oxidation of acrivastine with excess N-bromosuccinimide (NBS) and determination of the unconsumed NBS with, metol-sulphanilic acid (?max: 520 nm) or amaranth dye (?max: 530 nm). The reacted oxidant corresponds to the drug content. Beer’s law is obeyed over the concentration range 1.563-50, 2.0-20 and 1.0-10 ?g mL-1 for methods A, B and C, respectively. The limits of detection and quantitation were 0.40, 0.292 and 0.113 ?g mL-1 and 0.782, 0.973 and 0.376 ?g mL-1 for methods A, B and C, respectively. The HPLC method was validated for system suitability, linearity, precision, limits of detection and quantitation, specificity, stability and robustness. Stability tests were done through exposure of the analyte solution for four different stress conditions and the results indicate no interference of degradants with HPLC-method. The proposed methods was favorably applied for determination of acrivastine in capsules formulation. Statistical comparison of the obtained results from the analysis of the studied drug to those of the reported method using t- and F-tests showed no significant difference between them.

Gouda, Ayman A.; Hashem, Hisham; Jira, Thomas

2014-09-01

261

Development and validation of a rapid stability indicating HPLC-method using monolithic stationary phase and two spectrophotometric methods for determination of antihistaminic acrivastine in capsules.  

PubMed

Simple, rapid and accurate high performance liquid chromatographic (HPLC) and spectrophotometric methods are described for determination of antihistaminic acrivastine in capsules. The first method (method A) is based on accurate, sensitive and stability indicating chromatographic separation method. Chromolith® Performance RP-18e column, a relatively new packing material consisting of monolithic rods of highly porous silica, was used as stationary phase applying isocratic binary mobile phase of ACN and 25 mM NaH2PO4 pH 4.0 in the ratio of 22.5:77.5 at flow rate of 5.0 mL/min and 40°C. A diode array detector was used at 254 nm for detection. The elution time of acrivastine was found to be 2.080±0.032. The second and third methods (methods B and C) are based on the oxidation of acrivastine with excess N-bromosuccinimide (NBS) and determination of the unconsumed NBS with, metol-sulphanilic acid (?max: 520 nm) or amaranth dye (?max: 530 nm). The reacted oxidant corresponds to the drug content. Beer's law is obeyed over the concentration range 1.563-50, 2.0-20 and 1.0-10 ?g mL(-1) for methods A, B and C, respectively. The limits of detection and quantitation were 0.40, 0.292 and 0.113 ?g mL(-1) and 0.782, 0.973 and 0.376 ?g mL(-1) for methods A, B and C, respectively. The HPLC method was validated for system suitability, linearity, precision, limits of detection and quantitation, specificity, stability and robustness. Stability tests were done through exposure of the analyte solution for four different stress conditions and the results indicate no interference of degradants with HPLC-method. The proposed methods was favorably applied for determination of acrivastine in capsules formulation. Statistical comparison of the obtained results from the analysis of the studied drug to those of the reported method using t- and F-tests showed no significant difference between them. PMID:24813276

Gouda, Ayman A; Hashem, Hisham; Jira, Thomas

2014-09-15

262

Development and validation of simultaneous spectrophotometric and TLC-spectrodensitometric methods for determination of beclomethasone dipropionate and salbutamol in combined dosage form  

NASA Astrophysics Data System (ADS)

Spectrophotometric and TLC-spectrodensitometric methods were developed and validated for the simultaneous determination of beclomethasone dipropionate (BEC) and salbutamol (SAL). The spectrophotometric methods include dual wavelength, ratio difference, constant center coupled with a novel method namely, spectrum subtraction and mean centering with mean percentage recoveries and RSD 99.72 ± 1.07 and 99.70 ± 1.12, 100.25 ± 1.12 and 99.89 ± 1.12, 99.66 ± 1.85 and 99.19 ± 1.32, 100.74 ± 1.26 and 101.06 ± 0.90 for BEC and SAL respectively. The TLC-spectrodensitometric method was based on separation of both drugs on TLC aluminum plates of silica gel 60 F254, using benzene: methanol: triethylamine (10:1.5:0.5 v/v/v) as a mobile phase, followed by densitometric measurements of their bands at 230 nm. The mean percentage recoveries and RSD were 99.07 ± 1.25 and 101.35 ± 1.50 for BEC and SAL respectively. The proposed methods were validated according to ICH guidelines and were applied for the simultaneous analysis of the cited drugs in synthetic mixtures and pharmaceutical preparation. The methods were found to be rapid, specific, precise and accurate and can be successfully applied for the routine analysis of BEC and SAL in their pharmaceutical formulation with no need for prior separation. The results obtained were statistically compared to each other and to that of the reported HPLC method. The statistical comparison showed that there is no significant difference regarding both accuracy and precision.

Samir, Ahmed; Lotfy, Hayam M.; Salem, Hesham; Abdelkawy, Mohammed

2014-07-01

263

Development and validation of simultaneous spectrophotometric and TLC-spectrodensitometric methods for determination of beclomethasone dipropionate and salbutamol in combined dosage form.  

PubMed

Spectrophotometric and TLC-spectrodensitometric methods were developed and validated for the simultaneous determination of beclomethasone dipropionate (BEC) and salbutamol (SAL). The spectrophotometric methods include dual wavelength, ratio difference, constant center coupled with a novel method namely, spectrum subtraction and mean centering with mean percentage recoveries and RSD 99.72±1.07 and 99.70±1.12, 100.25±1.12 and 99.89±1.12, 99.66±1.85 and 99.19±1.32, 100.74±1.26 and 101.06±0.90 for BEC and SAL respectively. The TLC-spectrodensitometric method was based on separation of both drugs on TLC aluminum plates of silica gel 60 F254, using benzene: methanol: triethylamine (10:1.5:0.5 v/v/v) as a mobile phase, followed by densitometric measurements of their bands at 230 nm. The mean percentage recoveries and RSD were 99.07±1.25 and 101.35±1.50 for BEC and SAL respectively. The proposed methods were validated according to ICH guidelines and were applied for the simultaneous analysis of the cited drugs in synthetic mixtures and pharmaceutical preparation. The methods were found to be rapid, specific, precise and accurate and can be successfully applied for the routine analysis of BEC and SAL in their pharmaceutical formulation with no need for prior separation. The results obtained were statistically compared to each other and to that of the reported HPLC method. The statistical comparison showed that there is no significant difference regarding both accuracy and precision. PMID:24662761

Samir, Ahmed; Lotfy, Hayam M; Salem, Hesham; Abdelkawy, Mohammed

2014-07-15

264

Construction and evaluation of an automated flow injection-stopped flow analyser for multipoint reaction rate spectrophotometric methods. Determination of ammonia nitrogen, creatinine and phosphate  

PubMed Central

The construction and evaluation of a fully automated Flow Injection-Stopped Flow (FI-SF) spectrophotometric analyser is described. A microcomputer (Rockwell AIM 65) is used to control the analyser (sample injection, stop and start of the pump) through a suitable interface. Data acquisition is achieved using a 12 bit ADC card and a suitable subroutine in 6502 assembly language, allowing data sampling at a frequency of 7.5 kHz. The measurement interface and software were evaluated using a voltage ramp generator. A precision of 0.02-1.1% RSD (N =10) was obtained for voltage ramps in the range of 1-37 mVs-1. The FI-SF analyser was evaluated in routine analysis by developing FI-SF kinetic spectrophotometric methods for the determination of ammonia nitrogen (20-250 ppm, 0.4-2.5% RSD) based on the Berthelot reaction, creatinine (20-220 ppm, 0.9-3.6% RSD) based on the Jaffé reaction, and phosphate (5-30 ppm, 1.0-3.3% RSD) based on the phosphomolybdenum blue reaction. The reaction rate is measured by linear fitting of multiple absorbance readings vs time. Algorithms for automated estimation of the residence time, the linear range of the reaction curve, and data treatment are presented. PMID:18924905

Georgiou, Constantinos A.

1991-01-01

265

Thallimetric oxidations-VI Titrimetric and spectrophotometric methods for the determination of phosphite and analysis of binary mixtures of phosphite and oxalate.  

PubMed

Titrimetric and spectrophotometric methods have been developed for the estimation of phosphite at mmole and mumole levels, respectively. Thallium(III) is used as an oxidant and the thallium(I) produced is determined either oxidimetrically with potassium bromate or by measurement of the absorbance of thallium(III) at 260 nm in the presence of 0.1 M hydrochloric acid and 1 M perchloric acid. Based on the fact that phosphite and oxalate are oxidized under different conditions, methods are described for the analysis of binary mixtures of phosphite and oxalate. A method is also described for estimation of thallium(III) with phosphite as reluctant, and is applied for analysis of mixtures of thallium(I) and thallium(III). PMID:18965240

Rao, M S; Mohan Rao, A R; Ramana, K V; Sagi, S R

1991-08-01

266

G protein signaling in UV protection: methods for understanding the signals in young etiolated seedlings.  

PubMed

A seed is competent to respond to light soon after imbibition. A new developmental program begins in or on the ground where the young seedling may be exposed to heat, cold, drought, flooding (anoxia), salts, varying levels of visible light, and the topic of this paper, ultraviolet radiation. Herein what is described is a method for growing and maintaining seedlings, then methods of UV irradiation in order to measure discrete effects of UV wavelengths in signal transduction, very early in seedling development. The physiological response to an abiotic signal is partly dependent on the developmental state of the plant. Dark-grown seedlings of plant species possess young leaves or leaf primordia in a "suspended" state of development whereby exposure to sunlight, visible and UV, is required to initiate the leaf developmental program, including development of etioplasts or proplastids into fully functioning chloroplasts. In order for us to understand the initial and persisting effects of UV in seedlings, we "delay" light-induced development by carrying out all experiments in complete darkness between days 0 (seed) and day 7 (Arabidopsis). In this case, the UV regulation of a simple signaling pathway in Arabidopsis, G protein signaling in UV protection and acclimation early in development, is investigated with the use of several mutants and easily score-able phenotypes. PMID:23913039

Orozco-Nunnelly, Danielle A; Kaufman, Lon S; Warpeha, Katherine M

2013-01-01

267

A non-invasive analysis method for on-chip spectrophotometric detection using liquid-core waveguiding within a 3D architecture.  

PubMed

The on-chip measurement of absorbing species has proven to be challenging, particularly with respect to the sample pathlengths available in a miniaturised system. This paper demonstrates how the principles of total internal reflection can be utilised to form a liquid-core waveguide along a single microfluidic channel, increasing the sampling pathlength to 5 mm while maintaining a detection volume of < or = 1 microL. This was achieved using the Teflon fluoropolymers PTFE, FEP and AF as cladding for the liquid-core waveguide. In conjunction with a 3D chip architecture, the use of the liquid-core waveguide enables more efficient use of the probing light beam along with easy and effective coupling of the source, microfluidic chip and the detection system. The confirmation that waveguiding was occurring was successfully demonstrated and the subsequent spectrophotometric analysis of crystal violet provided a linear calibration with reproducibility (< 2.4% RSD) and limits of detection (< 1.3 microM), comparable to absorbance measurements made with a standard UV-Vis spectrophotometer. PMID:14700226

Duggan, Matthew P; McCreedy, Tom; Aylott, Jonathan W

2003-11-01

268

Total dissolved nitrogen analysis: comparisons between the persulfate, UV and high temperature oxidation methods  

Microsoft Academic Search

We compared the persulfate (PO), ultraviolet (UV), and high temperature oxidation (HTO) methods used to analyze total dissolved nitrogen (TDN) concentrations in aquatic samples to determine whether the three methods differed in terms of standard parameters (blanks, limits of detection and linearity, and precision) or in oxidation efficiency of standard compounds and field samples of varying salinity. The TDN concentrations

Deborah A. Bronk; Michael W. Lomas; Patricia M. Glibert; Karyn J. Schukert; Marta P. Sanderson

2000-01-01

269

Microwave-assisted of dispersive liquid-liquid microextraction and spectrophotometric determination of uranium after optimization based on Box-Behnken design and chemometrics methods  

NASA Astrophysics Data System (ADS)

In this study an analytical procedure based on microwave-assisted dispersive liquid-liquid microextraction (MA-DLLME) and spectrophotometric coupled with chemometrics methods is proposed to determine uranium. In the proposed method, 4-(2-pyridylazo) resorcinol (PAR) is used as a chelating agent, and chloroform and ethanol are selected as extraction and dispersive solvent. The optimization strategy is carried out by using two level full factorial designs. Results of the two level full factorial design (24) based on an analysis of variance demonstrated that the pH, concentration of PAR, amount of dispersive and extraction solvents are statistically significant. Optimal condition for three variables: pH, concentration of PAR, amount of dispersive and extraction solvents are obtained by using Box-Behnken design. Under the optimum conditions, the calibration graphs are linear in the range of 20.0-350.0 ng mL-1 with detection limit of 6.7 ng mL-1 (3?B/slope) and the enrichment factor of this method for uranium reached at 135. The relative standard deviation (R.S.D.) is 1.64% (n = 7, c = 50 ng mL-1). The partial least squares (PLS) modeling was used for multivariate calibration of the spectrophotometric data. The orthogonal signal correction (OSC) was used for preprocessing of data matrices and the prediction results of model, with and without using OSC, were statistically compared. MA-DLLME-OSC-PLS method was presented for the first time in this study. The root mean squares error of prediction (RMSEP) for uranium determination using PLS and OSC-PLS models were 4.63 and 0.98, respectively. This procedure allows the determination of uranium synthesis and real samples such as waste water with good reliability of the determination.

Niazi, Ali; Khorshidi, Neda; Ghaemmaghami, Pegah

2015-01-01

270

Microwave-assisted of dispersive liquid-liquid microextraction and spectrophotometric determination of uranium after optimization based on Box-Behnken design and chemometrics methods.  

PubMed

In this study an analytical procedure based on microwave-assisted dispersive liquid-liquid microextraction (MA-DLLME) and spectrophotometric coupled with chemometrics methods is proposed to determine uranium. In the proposed method, 4-(2-pyridylazo) resorcinol (PAR) is used as a chelating agent, and chloroform and ethanol are selected as extraction and dispersive solvent. The optimization strategy is carried out by using two level full factorial designs. Results of the two level full factorial design (2(4)) based on an analysis of variance demonstrated that the pH, concentration of PAR, amount of dispersive and extraction solvents are statistically significant. Optimal condition for three variables: pH, concentration of PAR, amount of dispersive and extraction solvents are obtained by using Box-Behnken design. Under the optimum conditions, the calibration graphs are linear in the range of 20.0-350.0 ng mL(-1) with detection limit of 6.7 ng mL(-1) (3?B/slope) and the enrichment factor of this method for uranium reached at 135. The relative standard deviation (R.S.D.) is 1.64% (n=7, c=50 ng mL(-1)). The partial least squares (PLS) modeling was used for multivariate calibration of the spectrophotometric data. The orthogonal signal correction (OSC) was used for preprocessing of data matrices and the prediction results of model, with and without using OSC, were statistically compared. MA-DLLME-OSC-PLS method was presented for the first time in this study. The root mean squares error of prediction (RMSEP) for uranium determination using PLS and OSC-PLS models were 4.63 and 0.98, respectively. This procedure allows the determination of uranium synthesis and real samples such as waste water with good reliability of the determination. PMID:25062051

Niazi, Ali; Khorshidi, Neda; Ghaemmaghami, Pegah

2015-01-25

271

Determination of pK(a) of felodipine using UV-Visible spectroscopy.  

PubMed

In the present study, for the first time, experimental pKa value of felodipine is reported. Dissociation constant, pKa, is one of the very important physicochemical properties of drugs. It is of paramount significance from the perspective of pharmaceutical analysis and dosage form design. The method used for the pKa determination of felodipine was essentially a UV-Visible spectrophotometric method. The spectrophotometric method for the pKa determination was opted by acknowledging the established fact that spectrophotometric determination of pKa produces most precise values. The pKa of felodipine was found to be 5.07. Furthermore, the ruggedness of the determined value is also validated in this study in order to produce exact pKa of the felodipine. PMID:23906645

Pandey, M M; Jaipal, A; Kumar, A; Malik, R; Charde, S Y

2013-11-01

272

Determination of pKa of felodipine using UV-Visible spectroscopy  

NASA Astrophysics Data System (ADS)

In the present study, for the first time, experimental pKa value of felodipine is reported. Dissociation constant, pKa, is one of the very important physicochemical properties of drugs. It is of paramount significance from the perspective of pharmaceutical analysis and dosage form design. The method used for the pKa determination of felodipine was essentially a UV-Visible spectrophotometric method. The spectrophotometric method for the pKa determination was opted by acknowledging the established fact that spectrophotometric determination of pKa produces most precise values. The pKa of felodipine was found to be 5.07. Furthermore, the ruggedness of the determined value is also validated in this study in order to produce exact pKa of the felodipine.

Pandey, M. M.; Jaipal, A.; Kumar, A.; Malik, R.; Charde, S. Y.

2013-11-01

273

Spectrophotometric and spectrofluorimetric studies on azilsartan medoxomil and chlorthalidone to be utilized in their determination in pharmaceuticals.  

PubMed

The recently approved angiotensin II receptor blocker, azilsartan medoxomil (AZL), was determined spectrophotometrically and spectrofluorimetrically in its combination with chlorthalidone (CLT) in their combined dosage form. The UV-spectrophotometric technique depends on simultaneous measurement of the first derivative spectra for AZL and CLT at 286 and 257 nm, respectively, in methanol. The spectrofluorimetric technique depends on measurement of the fourth derivative of the synchronous spectra intensities of AZL in presence of CLT at 298 nm in methanol. The effects of different solvents on spectrophotometric and spectrofluorimetric responses were studied. For, the spectrofluorimetric study, the effect of pH and micelle-assisted fluorescence enhancement were also studied. Linearity, accuracy, and precision were found to be satisfactory over the concentration ranges of 8-50 ?g mL(-1) and 2-20 ?g mL(-1) for AZL and CLT, respectively, in the spectrophotometric method as well as 0.01-0.08 ?g mL(-1) for AZL in the spectrofluorimetric method. The methods were successfully applied for the determination of the studied drugs in their co-formulated tablets. The developed methods are inexpensive and simple for the quality control and routine analysis of the cited drugs in bulk and in pharmaceuticals. PMID:24855334

Ebeid, Walid M; Elkady, Ehab F; El-Zaher, Asmaa A; El-Bagary, Ramzia I; Patonay, Gabor

2014-01-01

274

Spectrophotometric and Spectrofluorimetric Studies on Azilsartan Medoxomil and Chlorthalidone to Be Utilized in Their Determination in Pharmaceuticals  

PubMed Central

The recently approved angiotensin II receptor blocker, azilsartan medoxomil (AZL), was determined spectrophotometrically and spectrofluorimetrically in its combination with chlorthalidone (CLT) in their combined dosage form. The UV-spectrophotometric technique depends on simultaneous measurement of the first derivative spectra for AZL and CLT at 286 and 257 nm, respectively, in methanol. The spectrofluorimetric technique depends on measurement of the fourth derivative of the synchronous spectra intensities of AZL in presence of CLT at 298 nm in methanol. The effects of different solvents on spectrophotometric and spectrofluorimetric responses were studied. For, the spectrofluorimetric study, the effect of pH and micelle-assisted fluorescence enhancement were also studied. Linearity, accuracy, and precision were found to be satisfactory over the concentration ranges of 8–50 ?g mL?1 and 2–20 ?g mL?1 for AZL and CLT, respectively, in the spectrophotometric method as well as 0.01–0.08 ?g mL?1 for AZL in the spectrofluorimetric method. The methods were successfully applied for the determination of the studied drugs in their co-formulated tablets. The developed methods are inexpensive and simple for the quality control and routine analysis of the cited drugs in bulk and in pharmaceuticals. PMID:24855334

Ebeid, Walid M; Elkady, Ehab F; El-Zaher, Asmaa A; El-Bagary, Ramzia I; Patonay, Gabor

2014-01-01

275

Kinetic spectrophotometric determination of nizatidine and ranitidine in pharmaceutical preparations  

Microsoft Academic Search

A new simple and sensitive kinetic spectrophotometric method is described for analysis of nizatidine (I) and ranitidine (II). The method involves the reaction of the drugs with alkaline potassium permanganate, whereby a green color peaking at 610 nm is produced. The reaction is monitored spectrophotometrically by measuring the rate of change of absorbance of the resulting manganate species at 610

E. M. Hassan; F. Belal

2002-01-01

276

Spectrophotometric determination of metronidazole and secnidazole in pharmaceutical preparations  

Microsoft Academic Search

A rapid and sensitive spectrophotometric method is proposed for determination of metronidazole and secnidazole. The method depends on the reduction of metronidazole and secnidazole molecule with zinc dust and hydrochloric acid flowed by diazotization and coupling with 8-quinolinol to give red colored chromogens easily measured spectrophotometrically which has ?max = 500 nm. The experimental conditions were optimized and Berr's law was obeyed over

T. Saffaj; M. Charrouf; A. Abourriche; Y. Abboud; A. Bennamara; M. Berrada

2004-01-01

277

A simple spectrophotometric method for the determination of arsenic in industrial and environmental samples using 2,4-Dihydroxy benzophenone-2-amino thiophenol.  

PubMed

2,4-Dihydroxy benzophenone-2-amino thiophenol (BPBT) has been proposed as new analytical reagent for the direct non-extractive spectrophotometric determination of arsenic. The reagent reacts with arsenic in acidic medium (pH=6.0, sodium acetate-acetic acid buffer) to form light greenish yellow colored 1:1 (M:L) complex. Maximum absorbance was obtained at 343 nm and remains constant for over 24 h. The molar absorptivity and Sandell's sensitivity of BPBT are found to be 6.01×10(4) L mol(-1)cm(-1) and 0.0016 ?g cm(-2) respectively. The system obeys Beer's law in the range of 0.125-2.637 ?g/ml of As (III). Since BPBT method is more sensitive, it was applied for the determination of arsenic in some environmental water samples. PMID:24468982

Deepa, K; Lingappa, Y

2014-04-24

278

Comparative study for determination of some polycyclic aromatic hydrocarbons ‘PAHs' by a new spectrophotometric method and multivariate calibration coupled with dispersive liquid-liquid extraction  

NASA Astrophysics Data System (ADS)

A modified dispersive liquid-liquid extraction (DLLE) procedure coupled with spectrophotometric techniques was adopted for simultaneous determination of naphthalene, anthracene, benzo(a)pyrene, alpha-naphthol and beta-naphthol in water samples. Two different methods were used, partial least-squares (PLS) method and a new derivative ratio method, namely extended derivative ratio (EDR). A PLS-2 model was established for simultaneous determination of the studied pollutants in methanol, by using twenty mixtures as calibration set and five mixtures as validation set. Also, in methanol a novel (EDR) method was developed for determination of the studied pollutants, where each component in the mixture of the five PAHs was determined by using a mixture of the other four components as divisor. Chemometric and EDR methods could be also adopted for determination of the studied PAH in water samples after transferring them from aqueous medium to the organic one by utilizing dispersive liquid-liquid extraction technique, where different parameters were investigated using a full factorial design. Both methods were compared and the proposed method was validated according to ICH guidelines and successfully applied to determine these PAHs simultaneously in spiked water samples, where satisfactory results were obtained. All the results obtained agreed with those of published methods, where no significant difference was observed.

Abdel-Aziz, Omar; El Kosasy, A. M.; El-Sayed Okeil, S. M.

2014-12-01

279

Extractive Spectrophotometric Determination of Ambrisentan  

PubMed Central

Purpose: Ambrisentan (ABS) is an antihypertensive drug used in the treatment of pulmonary atrial hypertension. The survey of literature for ABS revealed only two spectrophotometric methods for its quantification. The reported methods lack the sensitivity. This study is aimed at developing two sensitive extractive spectrophotometric methods for the determination of ABS in bulk and in tablets. Methods: The proposed methods are based on the formation of colored chloroform extractable ion-pair complexes of ABS with methylene blue (MB method) and safranine O (SO method) in buffered solution at pH 9.8. The extracted complexes showed maximum absorbance at 525 and 515 nm for methylene blue and safranine O, respectively. Results: In both the methods, the calibration curve was linear from 1–15 µg mL-1 of drug. Apparent molar absorpitivities were 1.7911 x 105, 2.3272 x 105 L mol-1 cm-1; Sandell’s sensitivities were 0.0215, 0.0162 µg cm-2; LOD were 0.182, 0.175 µg mL-1; LOQ were 0.551, 0.531 µg mL-1 for methods MB and SO, respectively. The relative standard deviation and percent recovery ranged from 0.206–1.310% and 99.0–101.5%, respectively. Conclusion: The results demonstrate that the proposed methods are sensitive, precise, accurate and inexpensive. These methods can easily be used for the assay of ABS in quality control laboratories. PMID:24312841

Kumar, Namasani Santhosh; Rani, Avula Prameela; Visalakshi, Telu; Sekharan, Chandra Bala

2013-01-01

280

Ethanol Assay, UV-method (R-Biopharm, Cat. No. 10 176 290 035)  

E-print Network

Ethanol Assay, UV-method (R-Biopharm, Cat. No. 10 176 290 035) modified by Maitreya Dunham the assay since ethanol is volatile. Use the following chart to add the appropriate amount of reagents your samples at all times during the assay since ethanol is volatile. According to the kit, _A must

Dunham, Maitreya

281

Cisapride a green analytical reagent for rapid and sensitive determination of bromate in drinking water, bread and flour additives by oxidative coupling spectrophotometric methods.  

PubMed

Green analytical methods using Cisapride (CPE) as green analytical reagent was investigated in this work. Rapid, simple, and sensitive spectrophotometric methods for the determination of bromate in water sample, bread and flour additives were developed. The proposed methods based on the oxidative coupling between phenoxazine and Cisapride in the presence of bromate to form red colored product with max at 520 nm. Phenoxazine and Cisapride and its reaction products were found to be environmentally friendly under the optimum experimental condition. The method obeys beers law in concentration range 0.11-4.00 g ml(-1) and molar absorptivity 1.41 × 10(4) L mol(-1)cm(-1). All variables have been optimized and the presented reaction sequences were applied to the analysis of bromate in water, bread and flour additive samples. The performance of these method was evaluated in terms of Student's t-test and variance ratio F-test to find out the significance of proposed methods over the reference method. The combination of pharmaceutical drugs reagents with low concentration create some unique green chemical analyses. PMID:23261631

Al Okab, Riyad Ahmed

2013-02-15

282

Cisapride a green analytical reagent for rapid and sensitive determination of bromate in drinking water, bread and flour additives by oxidative coupling spectrophotometric methods  

NASA Astrophysics Data System (ADS)

Green analytical methods using Cisapride (CPE) as green analytical reagent was investigated in this work. Rapid, simple, and sensitive spectrophotometric methods for the determination of bromate in water sample, bread and flour additives were developed. The proposed methods based on the oxidative coupling between phenoxazine and Cisapride in the presence of bromate to form red colored product with max at 520 nm. Phenoxazine and Cisapride and its reaction products were found to be environmentally friendly under the optimum experimental condition. The method obeys beers law in concentration range 0.11-4.00 g ml-1 and molar absorptivity 1.41 × 104 L mol-1 cm-1. All variables have been optimized and the presented reaction sequences were applied to the analysis of bromate in water, bread and flour additive samples. The performance of these method was evaluated in terms of Student's t-test and variance ratio F-test to find out the significance of proposed methods over the reference method. The combination of pharmaceutical drugs reagents with low concentration create some unique green chemical analyses.

Al Okab, Riyad Ahmed

2013-02-01

283

Kinetic spectrophotometric H-point standard addition method for the simultaneous determination of diloxanide furoate and metronidazole in binary mixtures and biological fluids  

NASA Astrophysics Data System (ADS)

Simple, reliable, and sensitive kinetic spectrophotometric method has been developed for the simultaneous determination of diloxanide furoate and metronidazole using H-point standard addition method (HPSAM). The method is based on the oxidation rate difference of diloxanide and metronidazole by potassium permanganate in basic medium. A green color has been developed and measured at 610 nm. Different experimental parameters were carefully optimized. The limiting logarithmic and the initial-rate methods were adopted for the construction of the calibration curve of each individual reaction with potassium permanganate. Under the optimum conditions, Beer's law was obeyed in the range of 1.0-20.0 and 5.0-25.0 ?g ml-1 for diloxanide furoate and metronidazole, respectively. The detection limits were 0.22 ?g ml-1 for diloxanide furoate and 0.83 ?g ml-1 for metronidazole. Correlation coefficients of the regression equations were greater than 0.9970 in all cases. The precision of the method was satisfactory; the maximum value of relative standard deviation did not exceed 1.06% (n = 5). The accuracy, expressed as recovery was between 99.4% and 101.4% with relative error of 0.12 and 0.14 for diloxanide furoate and metronidazole, respectively. The proposed method was successfully applied for the simultaneous determination of both drugs in pharmaceutical dosage forms and human urine samples and compared with alternative HPLC method.

Issa, Mahmoud Mohamed; Nejem, R.'afat Mahmoud; Shanab, Alaa Mohamed Abu; Shaat, Nahed Talab

2013-10-01

284

Nonylphenols degradation in the UV, UV/H2O2, O3 and UV/O3 processes - comparison of the methods and kinetic study.  

PubMed

This paper describes the results of experiments on the decomposition of selected nonylphenols (NPs) in aqueous solutions using the UV, UV/H2O2, O3 and UV/O3 processes. The goal of the research was to determine the kinetic parameters of the above-mentioned processes, and to estimate their effectiveness. These substances were selected because of their ubiquitous occurrence in the aquatic environment, resistance to biodegradation and environmental significance. As a result of the experiments, the quantum yields of the 4-n-nonylphenol (4NP) and NP (technical mixture) photodegradation in aqueous solution were calculated to be 0.15 and 0.17, respectively. The values of the second-order rate constants of the investigated compounds with hydroxyl radical and NP with ozone were also determined. The estimated second-order rate constants of 4NP and NP with hydroxyl radicals were equal to 7.6 × 10(8)-1.3 × 10(9) mol(-1) L s(-1). For NP, the determined rate constant with ozone was equal to 2.01 × 10(6) mol(-1) L s(-1). The performed experiments showed that NP was slightly more susceptible to degradation by the UV radiation and hydroxyl radicals than 4NP. The study demonstrated also that the polychromatic UV-light alone and also in combination with selected oxidizers (i.e. hydrogen peroxide, ozone) may be successfully used for the removal of selected NPs from the aqueous medium. PMID:25714646

Felis, E; Miksch, K

2015-01-01

285

Development and validation of an high-performance liquid chromatographic, and a ultraviolet spectrophotometric method for determination of Ambroxol hydrochloride in pharmaceutical preparations  

PubMed Central

A high-performance liquid chromatographic (HPLC) and ultraviolet (UV) methods were developed and validated for the quantitative determination of Ambroxol hydrochloride (AMH) in pharmaceutical dosage form. HPLC was carried out by reversed phase (RP) technique on an RP-18 column with a mobile phase composed of acetonitrile and water (pH 3.5 adjusted with orthophosphoric acid [60:40, v/v]). UV method was performed with the ?max at 250 nm. Both the methods showed good linearity, reproducibility, and precision. No spectral or chromatographic interferences from the tablet excipients were found in UV and HPLC. The method was successfully applied to commercial tablets. Validation parameters such as linearity, precision, accuracy, and specificity were determined. The HPLC Limit of detection (LOD) and Limit of quantification (LOQ) for Ambroxol were found to be 1 and 5 ng/ml, respectively. The UV LOD and LOQ for Ambroxol were found to be 1 and 4 ?g/ml, respectively. The results were statistically compared using one-way analysis of variance. The proposed economical method could be applicable for routine analysis of AMH and monitoring of the quality of marketed drugs. PMID:23662284

Muralidharan, Selvadurai; Kumar, Jaya Raja; Dhanara, Sokkalingam Arumugam

2013-01-01

286

Clinical Investigations Spectrophotometric intracutaneous analysis: a new technique  

E-print Network

Clinical Investigations Spectrophotometric intracutaneous analysis: a new technique for imaging. Objectives To present the early results of a clinical trial with SIA. Methods Spectrophotometric inputs from in a dataset of 348 pigmented lesions (52 melanomas) and compared very favourably with dermatoscopy when

Claridge, Ela

287

A New Spectrophotometric Method for Determination of Phenylpropanolamine HCl in its Pharmaceutical Formulations via Reaction with 2,3,5,6-tetrachloro-1,4-benzoquinone  

PubMed Central

A selective and simple spectrophotometric method has been developed for the determination of phenylpropanolamine HCl (PPA) in its dosage forms. The method was based on the formation of a colored N-vinyl chlorobenzoquinone derivative of PPA through its reaction with 2,3,5,6-tetrachloro-1,4-benzoquinone in presence of acetaldehyde. The colored product exhibits maximum absorbance at 650 nm. Different experimental parameters affecting formation and stability of the product were carefully studied and optimized. The stoichiometry of the reaction was determined, and the reaction pathway was postulated. The absorbance concentration plot was rectilinear over the range of 5-100 ?g/mL with Limit of Detection (LOD) and Limit of Quantitation (LOQ) of 0.244 ?g/mL and 0.74 ?g/mL respectively. The analytical performance of the method was fully validated, and the results were satisfactory. The proposed method was successfully applied to the determination of PPA in its commercial dosage forms including tablets, capsules and syrups with good recoveries. Statistical comparison of the results with those of the comparison method showed good agreement and proved that there was no significant difference in the accuracy and precision between the reference and the proposed methods. The mechanism of the reaction pathway was postulated. PMID:23675189

Walash, M. I.; El-Enany, N.; Saad, S.

2010-01-01

288

Extractive spectrophotometric methods for the determination of oxomemazine hydrochloride in bulk and pharmaceutical formulations using bromocresol green, bromocresol purple and bromophenol blue.  

PubMed

Three simple, sensitive and accurate spectrophotometric methods have been developed for the determination of oxomemazine hydrochloride in bulk and pharmaceutical formulations. These methods are based on the formation of yellow ion-pair complexes between the examined drug and bromocresol green (BCG), bromocresol purple (BCP), and bromophenol blue (BPB) as sulphophthalein dyes in acetate-HCl buffer of pH 3.6, 3.4, and 4.0, respectively. The formed complexes were extracted with dichloromethane and measured at 405 nm for all three systems. The best conditions of the reactions were studied and optimized. Beer's law was obeyed in the concentration ranges 2.0-12, 2.0-13, and 2.0-14 microg mL(-1) with molar absorptivities of 3.2 x 10(4), 3.7 x 10(4), and 3.1 x 10(4) L mol(-1) cm(-1) for the BCG, BCP, and BPB methods, respectively. Sandell's sensitivity, correlation coefficient, detection and quantification limits are also calculated. The proposed methods have been applied successfully for the analysis of the drug in pure form and in its dosage forms. No interference was observed from common pharmaceutical excipients. Statistical comparison of the results with those obtained by HPLC method shows excellent agreement and indicates no significant difference in accuracy and precision. PMID:15864789

El-Didamony, Akram M

2005-04-01

289

Fully validated simultaneous determination of bisoprolol fumarate and hydrochlorothiazide in their dosage forms using different voltammetric, chromatographic, and spectrophotometric analytical methods.  

PubMed

Voltammetric, chromatographic, and spectrophotometric methods were developed for the simultaneous determination of bisoprolol fumarate (BIS) and hydrochlorothiazide (HCZ). Differential pulse and square wave voltammetry techniques were used to analyze BIS and HCZ simultaneously by measuring at about 1400 and 1100 mV, respectively. RP-HPLC was the second method for simultaneous analysis of the compounds. The mixture of BIS, HCZ, and moxifloxacin as an internal standard was separated on an RP Zorbax Eclipse XDB-C18 column (150 x 4.6 mm, id, 5 microm particle size) using acetonitrile-15 mM phosphate (25+75, v/v) mobile phase at a 1.0 mL/min flow rate. The third method was based on first derivative of the ratio-spectra method obtained from the measurements of the amplitudes at 246 and 257 nm for BIS and HCZ, respectively. All the proposed methods were effectively applied for the simultaneous determination of BIS and HCZ in tablet dosage forms without any time-consuming extraction, sample preparation, or derivatization procedures. PMID:23513956

Bozal, Burcin; Gumustas, Mehmet; Dogan-Topal, Burcu; Uslu, Bengi; Ozkan, Sibel A

2013-01-01

290

Absorption spectrophotometric study of supramolecular complexation of [60]- and [70]fullerenes with 24,26-dimethoxy-25,27-dihydroxy calix[4]arene  

Microsoft Academic Search

Supramolecular interactions of 24,26-dimethoxy-25,27-dihydroxy calix[4]arene (1) with [60]- and [70]fullerenes have been studied in only chloroform and in a ternary solvent mixture comprising of chloroform, ethyl alcohol and toluene by UV–vis absorption spectrophotometric method. The experimental results are explained using the model that takes into account the interaction between electronic subsystems of 1 and fullerene. The most interesting feature is

Sumanta Bhattacharya; Sandip K. Nayak; Subrata Chattopadhyay; Manas Banerjee

2006-01-01

291

A simple HPLC-UV method for the determination of ciprofloxacin in human plasma.  

PubMed

A rapid and sensitive HPLC-UV method for the determination of ciprofloxacin in human plasma is described. Protein precipitation with acetonitrile was used to separate the drug from plasma protein. An ACE(®) 5 C18 column (250mm×4.6mm, 5?m) with an isocratic mobile phase consisting of phosphate buffer (pH 2.7) and acetonitrile (77:23, v/v) was used for separation. The UV detector was set at 277nm. The method was validated in the linear range of 0.05-8?g/ml with acceptable inter- and intra-assay precision, accuracy and stability. The method is simple and rapid and can be used to quantify this widely used antibiotic in the plasma of patients suffering from Peripheral Arterial Disease. PMID:25813900

Vella, Janis; Busuttil, Francesca; Bartolo, Nicolette Sammut; Sammut, Carmel; Ferrito, Victor; Serracino-Inglott, Anthony; Azzopardi, Lilian M; LaFerla, Godfrey

2015-05-01

292

Validated spectrofluorimetric and spectrophotometric methods for the determination of brimonidine tartrate in ophthalmic solutions via derivatization with NBD-Cl. Application to stability study.  

PubMed

Two simple, selective and accurate methods were developed and validated for the determination of brimonidine tartrate (BT) in pure state and pharmaceutical formulations. Both methods are based on the coupling of the drug with 4-chloro-7-nitro-2,1,3-benzoxadiazole in borate buffer (pH?8.5) at 70?°C and measurement of the reaction product spectrophotometrically at 407?nm (method I) or spectrofluorimetrically at 528?nm upon excitation at 460?nm (method II). The calibration graphs were rectilinear over the concentration ranges of 1.0-16.0 and 0.1-4.0?µg/mL with lower detection limits of 0.21 and 0.03, and lower quantification limits of 0.65 and 0.09?µg/mL for methods I and II, respectively. Both methods were successfully applied to the analysis of commercial ophthalmic solution with mean recovery of 99.50?±?1.00 and 100.13?±?0.71%, respectively. Statistical analysis of the results obtained by the proposed methods revealed good agreement with those obtained using a comparison method. The proposed spectrofluorimetric method was extended to a stability study of BT under different ICH-outlined conditions such as alkaline, acidic, oxidative and photolytic degradation. Furthermore, the kinetics of oxidative degradation of the drug was investigated and the apparent first-order reaction rate constants, half-life times and Arrhenius equation were estimated. The proposed methods are practical and valuable for routine applications in quality control laboratories for the analysis of BT. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25044105

Ibrahim, F; El-Enany, N; El-Shaheny, R N; Mikhail, I E

2015-05-01

293

Stability indicating HPLC-UV method for determination of dapoxetine HCl in pharmaceutical product.  

PubMed

A stability-indicating HPLC-UV method for the determination of dapoxetine hydrochloride in solution and pharmaceutical product was developed. The mobile phase was composed of acetonitrile and 0.2 M ammonium acetate buffer at 50 : 50 ratio. The chromatographic parameters, theoretical plates (N), tailing factor (T), capacity factor (k') and peak asymmetry factor (As) were calculated. Stress degradation studies, namely, acid, alkali, oxidation, heat and UV light, were performed. The analyte was eluted at 5.8 min using gradient system at a flow rate of 1.5 mL/min. The theoretical plates count was > 2000, tailing factor < 1.54, capacity factor > 5.38 and peak asymmetry factor was < 1.10. The method was linear from 1 to 40 microg/mL with a correlation coefficient of 0.9994. The intraday precision and accuracy values were 0.14-1.54% and 0.63-1.83%, respectively. On the other hand, the interday precision and accuracy results were 0.49-1.83% and 1.15-1.85%, respectively. The drug solution was stable at ambient room temperature (26 degrees C) for 48 h. Dapoxetine HCI was found susceptible to oxidation and degraded slightly under acid and alkali conditions but was stable under UV light and heat. No interference from tablet excipiets and degradation products was found. Hence, the method can be employed as a stability-indicating method for the determination of dapoxetine HCl in pharmaceutical products. PMID:25265818

Liew, Kai Bin; Peh, Kok Khiang

2014-01-01

294

Simultaneous Determination of Cobalt(II) and Nickel(II) by Fourth-Order Derivative Spectrophotometric Method Using 2-Hydroxy-3-Methoxy Benzaldehyde Thiosemicarbazone  

PubMed Central

A simple and new simultaneous fourth derivative spectrophotometric method is proposed for the analysis of a two-component system containing cobalt(II) and nickel(II) without separation using 2-hydroxy-3-methoxy benzaldehyde thiosemicarbazone (HMBATSC) as a chromophoric reagent. The reagent reacts with cobalt(II) and nickel(II) at pH 6.0, forming soluble brown and yellow colored species, respectively. Cobalt(II) and nickel(II) present in themixture are simultaneously determined without solving the simultaneous equations bymeasuring the fourth derivative amplitudes at 468.5 nm and 474.5 nm, respectively. The derivative amplitudes obey Beer's law at 468.5 nm and 474.5 nm for Co(II) and Ni(II) in the range 0.059–3.299 ?g mL?1 and 0.058–3.285 ?g mL?1 respectively. A large number of foreign ions do not interfere in the present method. The present simultaneous method is used for the determination of micro amounts of cobalt in biological samples, nickel in plant samples, and in some alloy steels and soil sample. PMID:17671609

Kumar, A. Praveen; Reddy, P. Raveendra; Reddy, V. Krishna

2007-01-01

295

Development and Validation of Pregabalin in Bulk, Pharmaceutical Formulations and in Human Urine Samples by UV Spectrophotometry.  

PubMed

A simple and sensitive UV spectrophotometric method was developed and validated for the determination of pregabalin in bulk, pharmaceutical formulations and in human urine samples. The method was linear in the range of 0.5-5.0 ?g/ml. There is no generally accepted method for the determination of pregabalin. The absorbance was measured at 210 nm. The method was validated with respect to accuracy, precision, specificity, ruggedness, and robustness, limit of detection and limit of quantitation. This method was used successfully for the quality assessment of five pregabalin drug products and in human urine samples with good precision and accuracy. This is found to be simple, specific, precise, accurate, reproducible and low cost UV Spectrophotometric method. PMID:23675132

Gujral, Rajinder Singh; Haque, Sk Manirul; Shanker, Prem

2009-06-01

296

Transparent UV curable antistatic hybrid coatings on polycarbonate prepared by the sol–gel method  

Microsoft Academic Search

UV curable, hard, and transparent organic–inorganic hybrid coatings with covalent links between the inorganic and the organic networks were prepared by the sol–gel method. These hybrid coating materials were synthesised using a commercially available, acrylate end-capped polyurethane oligomeric resin, hexanedioldiacrylate (HDDA) as a reactive solvent, 3-(trimethoxysilyl)propoxymethacrylate (MPTMS) as a coupling agent between the organic and inorganic phase, and a metal

M. E. L. Wouters; D. P. Wolfs; M. C. van der Linde; J. H. P. Hovens; A. H. A. Tinnemans

2004-01-01

297

HPLC Method with UV Detection for the Determination of trans?Resveratrol in Plasma  

Microsoft Academic Search

The main representative of phytoalexins (biologically active substances produced by the plant as an immediate immunological response to infections or abiotic stresses) in wine grapes (Vitis vinifera) is the stilbene trans?resveratrol. The proposed method for the determination of trans?resveratrol in blood plasma is based on reversed phase HPLC utilizing UV detection (310 nm), under isocratic conditions (1.0 mL\\/min), with mobile phase consisting

Angelos Katsagonis; Michael A. Koupparis

2005-01-01

298

REVIEW ARTICLE: Spectrophotometric applications of digital signal processing  

NASA Astrophysics Data System (ADS)

Spectrophotometry is more and more often the method of choice not only in analysis of (bio)chemical substances, but also in the identification of physical properties of various objects and their classification. The applications of spectrophotometry include such diversified tasks as monitoring of optical telecommunications links, assessment of eating quality of food, forensic classification of papers, biometric identification of individuals, detection of insect infestation of seeds and classification of textiles. In all those applications, large numbers of data, generated by spectrophotometers, are processed by various digital means in order to extract measurement information. The main objective of this paper is to review the state-of-the-art methodology for digital signal processing (DSP) when applied to data provided by spectrophotometric transducers and spectrophotometers. First, a general methodology of DSP applications in spectrophotometry, based on DSP-oriented models of spectrophotometric data, is outlined. Then, the most important classes of DSP methods for processing spectrophotometric data—the methods for DSP-aided calibration of spectrophotometric instrumentation, the methods for the estimation of spectra on the basis of spectrophotometric data, the methods for the estimation of spectrum-related measurands on the basis of spectrophotometric data—are presented. Finally, the methods for preprocessing and postprocessing of spectrophotometric data are overviewed. Throughout the review, the applications of DSP are illustrated with numerous examples related to broadly understood spectrophotometry.

Morawski, Roman Z.

2006-09-01

299

Chemometric-assisted spectrophotometric methods and high performance liquid chromatography for simultaneous determination of seven ?-blockers in their pharmaceutical products: A comparative study.  

PubMed

Chemometric-assisted spectrophotometric methods and high performance liquid chromatography (HPLC) were developed for the simultaneous determination of the seven most commonly prescribed ?-blockers (atenolol, sotalol, metoprolol, bisoprolol, propranolol, carvedilol and nebivolol). Principal component regression PCR, partial least square PLS and PLS with previous wavelength selection by genetic algorithm (GA-PLS) were used for chemometric analysis of spectral data of these drugs. The compositions of the mixtures used in the calibration set were varied to cover the linearity ranges 0.7-10?gml(-1) for AT, 1-15?gml(-1) for ST, 1-15?gml(-1) for MT, 0.3-5?gml(-1) for BS, 0.1-3?gml(-1) for PR, 0.1-3?gml(-1) for CV and 0.7-5?gml(-1) for NB. The analytical performances of these chemometric methods were characterized by relative prediction errors and were compared with each other. GA-PLS showed superiority over the other applied multivariate methods due to the wavelength selection. A new gradient HPLC method had been developed using statistical experimental design. Optimum conditions of separation were determined with the aid of central composite design. The developed HPLC method was found to be linear in the range of 0.2-20?gml(-1) for AT, 0.2-20?gml(-1) for ST, 0.1-15?gml(-1) for MT, 0.1-15?gml(-1) for BS, 0.1-13?gml(-1) for PR, 0.1-13?gml(-1) for CV and 0.4-20?gml(-1) for NB. No significant difference between the results of the proposed GA-PLS and HPLC methods with respect to accuracy and precision. The proposed analytical methods did not show any interference of the excipients when applied to pharmaceutical products. PMID:25681811

Abdel Hameed, Eman A; Abdel Salam, Randa A; Hadad, Ghada M

2015-04-15

300

Optimized and Validated Spectrophotometric Methods for the Determination of Roxatidine Acetate Hydrochloride in Drug Formulations Using 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone and p -Chloranilic Acid  

Microsoft Academic Search

Two simple and sensitive spectrophotometric procedures are proposed for the determination of roxatidine in pure form and in tablets. Both methods are based on the charge transfer complexation reaction of the drug with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) or p-chloranilic acid resulting in colored products. In both cases, the absorbance measurement was made at 530 nm. Beer’s law was obeyed in the concentration

Rahman Nafisur; Kashif Mohammad

2005-01-01

301

A Spectrophotometric Analysis of Pigments in Apples  

Microsoft Academic Search

Methods of pigment extraction using traditional polar organic solvents (acetone or methanol) were compared to those employing a chloroform–methanol mixture. We found that, for spectrophotometric pigment analysis in the apple peel, the cuticular lipids must be preliminarily extracted from the samples with chloroform and MgO must be added during homogenization to prevent pigment degradation. The traditional extraction did not result

A. E. Solovchenko; O. B. Chivkunova; M. N. Merzlyak; I. V. Reshetnikova

2001-01-01

302

SPECTROPHOTOMETRIC DETERMINATION OF CERIUM WITH THENOYLTRIFLUOROACETONE  

Microsoft Academic Search

A spectrophotometric method for the determination of microgram amounts ; of cerium with thenoyltrifluoroacetone (TTA) is described. After oxidation with ; sodium bromate, cerium(IV) is extracted with 0.5M TTA in xylene from a 1N ; sulfuric acid solution. The absorbance of the organic phase is measured at 440 m ; mu or 450 m mu . Beer's law is followed

Hiroshi Onishi; C. V. Banks

1963-01-01

303

Detection of ibuprofen and ciprofloxacin by solid-phase extraction and UV/Vis spectroscopy  

NASA Astrophysics Data System (ADS)

A simple and economic solid-phase extraction coupled with UV/Vis spectrophotometric method is described for the analysis of ibuprofen and ciprofloxacin. Following solid-phase extraction from model wastewater samples containing standard ibuprofen or ciprofloxacin, elutes were analyzed by a UV/Vis spectrophotometer at 225 nm for ibuprofen and 280 nm for ciprofloxacin. The assay was linear for both compounds with good coefficients of correlation. This method shows good recoveries for both compounds with 101.0 ± 9.8% for ibuprofen and 99.4 ± 11.8% ciprofloxacin.

Zhou, Zhengwei; Jiang, Jia Qian

2012-07-01

304

A facile method for the assessment of DNA damage induced by UV-activated nanomaterials  

NASA Astrophysics Data System (ADS)

Fluorescent microscopy observation of gene-size DNA (T4 phage DNA or ? phage DNA) was used to assess DNA damage induced by UV irradiation in the presence of nanomaterials, such as QDs (quantum dots: CdSe/ZnS semiconductor nanoparticles), the water-soluble fullerene derivative C60(OH)n (n = 6-12) and titanium oxide nanoparticles of 25 nm in diameter. The magnitude of DNA damage could be simply evaluated based on the degree of shortening of the stretched DNA image. This method showed that DNA damage was amplified by the action of QDs under irradiation by C-band (?max = 254 nm) or B-band (?max = 303 nm) UV. Smaller QDs that emitted higher-energy fluorescence (?emmax = 565 nm) induced more severe damage than medium- and larger-size QDs that emitted longer-wavelength fluorescence (?emmax = 605 and 705 nm, respectively). The fullerene derivative and TiO2 nanoparticles caused DNA damage even under irradiation by A-band UV (?max = 365 nm) and showed more severe DNA damage than QDs under similar conditions.

Yamazaki, Yuka; Zinchenko, Anatoly A.; Murata, Shizuaki

2011-07-01

305

A comparative study of validated spectrophotometric and TLC- spectrodensitometric methods for the determination of sodium cromoglicate and fluorometholone in ophthalmic solution  

PubMed Central

The determination of sodium cromoglicate (SCG) and fluorometholone (FLU) in ophthalmic solution was developed by simple, sensitive and precise methods. Three spectrophotometric methods were applied: absorptivity factor (a-Factor method), absorption factor (AFM) and mean centering of ratio spectra (MCR). The linearity ranges of SCG were found to be (2.5–35 ?g/mL) for (a-Factor method) and (MCR); while for (AFM), it was found to be (7.5–50 ?g/mL). The linearity ranges of FLU were found to be (4–16 ?g/mL) for (a-Factor method) and (AFM); while for (MCR), it was found to be (2–16 ?g/mL). The mean percentage recoveries/RSD for SCG were found to be 100.31/0.90, 100.23/0.57 and 100.43/1.21; while for FLU, they were found to be 100.11/0.56, 99.97/0.35 and 99.94/0.88 using (a-Factor method), (AFM) and (MCR), respectively. A TLC-spectrodensitometric method was developed by separation of SCG and FLU on silica gel 60 F254 using chloroform:methanol:toluene:triethylamine in the ratio of (5:2:4:1 v/v/v/v) as developing system, followed by spectrodensitometric measurement of the bands at 241 nm. The linearity ranges and the mean percentage recoveries/RSD were found to be (0.4–4.4 ?g/band), 100.24/1.44 and (0.2–1.6 ?g/band), 99.95/1.50 for SCG and FLU, respectively. A comparative study was conducted between the proposed methods to discuss the advantage of each method. The suggested methods were validated in compliance with the ICH guidelines and were successfully applied for the determination of SCG and FLU in their laboratory prepared mixtures and commercial ophthalmic solution in the presence of benzalkonium chloride as a preservative. These methods could be an alternative to different HPLC techniques in quality control laboratories lacking the required facilities for those expensive techniques. PMID:24227962

Saleh, Sarah S.; Lotfy, Hayam M.; Hassan, Nagiba Y.; Elgizawy, Samia M.

2013-01-01

306

Method validation using weighted linear regression models for quantification of UV filters in water samples.  

PubMed

This paper describes the validation of a method consisting of solid-phase extraction followed by gas chromatography-tandem mass spectrometry for the analysis of the ultraviolet (UV) filters benzophenone-3, ethylhexyl salicylate, ethylhexyl methoxycinnamate and octocrylene. The method validation criteria included evaluation of selectivity, analytical curve, trueness, precision, limits of detection and limits of quantification. The non-weighted linear regression model has traditionally been used for calibration, but it is not necessarily the optimal model in all cases. Because the assumption of homoscedasticity was not met for the analytical data in this work, a weighted least squares linear regression was used for the calibration method. The evaluated analytical parameters were satisfactory for the analytes and showed recoveries at four fortification levels between 62% and 107%, with relative standard deviations less than 14%. The detection limits ranged from 7.6 to 24.1 ng L(-1). The proposed method was used to determine the amount of UV filters in water samples from water treatment plants in Araraquara and Jau in São Paulo, Brazil. PMID:25281096

da Silva, Claudia Pereira; Emídio, Elissandro Soares; de Marchi, Mary Rosa Rodrigues

2015-01-01

307

Extractive Spectrophotometric Methods for the Determination of Zolmitriptan in Bulk Drug and Pharmaceutical Formulation Using Bromocresol Green  

NASA Astrophysics Data System (ADS)

Considering the basic property of zolmitriptan (ZMT) to generate ion-pairs with sulfonephthalein dyes two methods have been developed for its assay in bulk drug and dosage form. The first method (method A) is based on the formation of a colored ion-pair complex (1:1 drug:dye) of ZMT with bromocresol green (BCG) at pH 4.20 ± 0.01 and extraction of the complex into chloroform followed by measurement of the yellow ion-pair complex at 435 nm. In the second method (method B), the drug-dye ion-pair complex was treated with ethanolic potassium hydroxide in ethanolic medium and the resulting base form of the dye was measured at 630 nm. Beer's law was obeyed in the concentration range of 0.8-18.0 and 0.08-1.4 ?g/ml for method A and B, respectively, and the corresponding molar absorptivity values were 1.50?104 and 1.52?105 l/(mol?cm). The Sandell sensitivity values were 0.0191 and 0.0019 ?g/cm2 for method A and method B, respectively. The stoichiometry of the ion-pair complex formed between the drug and dye (1:1) was determined by Job's continuous variation method and the stability constant of the complex was also calculated. The proposed method was successfully extended to dosage form (tablets).

Prashanth, K. N.; Swamy, N.; Basavaiah, K.

2013-11-01

308

Simultaneous spectrophotometric and mechanical property characterization of skin  

NASA Astrophysics Data System (ADS)

Both reflectance spectroscopy and the determination Young's Modulus of skin have shown promise for identifying skin pathology. At present, these determinations are carried out using separate methodologies. This study demonstrates a new technology combining digital UV/VIS reflectance spectroscopy and vacuum aspiration for simultaneously determining the reflectance spectrum and mechanical properties of human skin tissue. A small hand held prototype device incorporating fiber-optic light guides into a vacuum channel was calibrated using various elastic materials subjected to increments of stress by vacuum from 0 to 25 in Hg. The intensity of a UV/VIS light beam reflected from the material at each vacuum increment was compared to the resulting material strain. The reflected beam was also spectrophotometrically analyzed. Skin types were similarly evaluated comparing normal and scar tissue and skin of various ages and coloration. An exponential relationship between reflected beam intensity and the amount of strain resulting from vacuum increments was observed. Young's Modulus (calculated from Aoki et. al equation) and spectra from normal skin and scar tissue were in agreement with previously published observations. Age related decreases in skin elasticity were also demonstrated. In the reflectance spectra, oxy and deoxy-hemoglobin absorbance bands were detected, becoming significantly enhanced at increased levels of vacuum. Melanin absorbance was also easily detected and appeared to correlate with skin coloration. Since superficial skin pathologies have characteristic spectroscopic and mechanical properties, this technique may provide a promising new approach for rapid, non-invasive method for the evaluation of skin lesions.

Bunegin, Leonid; Moore, Jeffery B.

2006-02-01

309

A new method for the selection of measuring UV sites based on cloud classification from satellite data  

NASA Astrophysics Data System (ADS)

Methods applied on efficient planning of ground-based monitoring networks of surface solar ultraviolet (UV) irradiance could provide valuable scientific results and be useful for accurate monitoring and assessment of climatic values for UV-health studies. Based on the dominance of cloud effect on solar irradiance and the advantage of the high spatial resolution of a geostationary satellite, a novel method is presented for optimizing the location of UV measuring sites. The k-means algorithm is used for cluster analysis and the validation of the clustering method reveals that the variability of surface solar UV irradiance due to cloudiness over Greece could be sufficiently monitored with the establishment of 23-28 ground-based instruments.

Zagouras, A.; Kazantzidis, A.; Nikitidou, E.

2013-05-01

310

Sensitive Spectrophotometric Methods for Quantitative Determination of Gatifloxacin in Pharmaceutical Formulations using Bromate-Bromide, Thiocyanate and Tiron as Reagents  

Microsoft Academic Search

Two simple, sensitive and rapid methods are described for the determination of gatifloxacin sesqui hydrate (GTF) in bulk drug and in formulations using bromate-bromide as the oxidimetric reagent. The methods are based on the oxidation of GTF by in situ generated bromine followed by determination of unreacted bromine by two different reactions. In one procedure, the residual bromine is reduced

Basavaiah Kanakapura; Anil Kumar; Urdigere Rangachar

2007-01-01

311

Simultaneous determination of antazoline and naphazoline by the net analyte signal standard addition method and spectrophotometric technique.  

PubMed

A novel net analyte signal standard addition method (NASSAM) was used for simultaneous determination of the drugs anthazoline and naphazoline. The NASSAM can be applied for determination of analytes in the presence of known interferents. The proposed method is used to eliminate the calibration and prediction steps of multivariate calibration methods; the determination is carried out in a single step for each analyte. The accuracy of the predictions against the H-point standard addition method is independent of the shape of the analyte and interferent spectra. The net analyte signal concept was also used to calculate multivariate analytical figures of merit, such as LOD, selectivity, and sensitivity. The method was successfully applied to the simultaneous determination of anthazoline and naphazoline in a commercial eye drop sample. PMID:21313830

Asadpour-Zeynali, Karim; Ghavami, Raoof; Esfandiari, Roghayeh; Soheili-Azad, Payam

2010-01-01

312

Polymerization Evaluation by Spectrophotometric Measurements.  

ERIC Educational Resources Information Center

Discusses polymerization evaluation by spectrophotometric measurements by considering: (1) association degrees and molar absorptivities; (2) association degrees and equilibrium constants; and (3) absorbance and equilibrium constants. (JN)

Dunach, Jaume

1985-01-01

313

Dissolved organic carbon interferences in UV nitrate measurements and possible mitigation methods  

NASA Astrophysics Data System (ADS)

Nitrate can be the limiting nutrient in many aquatic ecosystems and has been implicated in the degradation of surface and ground water quality. Understanding its fate and transport requires measurements at high temporal resolution in situ for extended periods of time to observe a range of natural and anthropogenic inputs. These measurements are most efficiently made by in situ sensors, preferably without chemical manipulation. The development of in situ ultraviolet spectrometers with high spectral resolution (0.8 nm) and short response time (1 s) have provided the ability to make in situ measurements of nitrate concentration by measuring its absorbance in the UV wavelengths (200nm-400nm). Like many other regions, springs in Florida have shown increasing nitrate levels in recent years. Because many spring runs in Florida ultimately enter highly colored rivers with high humic DOC content, UV nitrate analyzers cannot operate according to specifications under such light limiting conditions and can result in erroneous or even unattainable readings. Here we present an analysis of interferences caused by dissolved organic carbon (DOC) on the measured nitrate concentration by the Satlantic SUNA (Submersible Ultraviolet Nitrate Analyzer). Dissolved organic carbon absorption of UV irradiation is well documented in the literature and the results of this study clearly demonstrate that high DOC concentrations impact in situ sensor nitrate concentration measurements. Interferences caused by DOC were estimated through bench tests of natural water collected from the upper reaches of the Santa Fe River (USGS Monitoring Station 2322700) and found to have DOC concentration of approximately 50 mg/L and N03 concentration of 0.04 mg/L. The SUNA was operated in a continuous sample mode (about 1 sample per second) to measure nitrate concentrations in this water that was diluted to DOC concentrations of 2.5, 5.0, 10.0, and 12.5 mg/L DOC and nitrate concentrations of 0.05, 0.10, 0.20, 0.50, and 1.00 mg/L NO3. Each DOC dilution and standard was measured for 5 minutes. At concentrations above 10 mg/L, the error associated with the measurements was > 15%. Below that concentration the error was 5%. Analysis of the spectral data of this experiment and from the study site indicate that significant attenuation at UV wavelengths causes most of the loss of the nitrate signal and error. It is thus critical that the DOC be removed or deactivated as part of the in situ UV-based nitrate analysis. While this attenuation could be overcome by shortening the path length of the light beam, a shortened pathlength would also reduce sensitivity. To remove the DOC interference, we have constructed a UV photoreactor by winding 7 m of PTFE tubing around a quartz tube. The assembly was wrapped in reflective aluminum foil. A low-pressure UV lamp (10 Watts output, 95% emitted at the mercury resonance wavelength of 254 nm) was placed inside the quartz tube. This method should mitigate interferences caused by DOC. The extent of mitigation is currently being determined and will be described in the presentation.

Thomas, R. G.; Foster, C. R.; Cohen, M. J.; Martin, J. B.; Delfino, J. J.

2010-12-01

314

Determination of nimesulide in pharmaceutical dosage forms by second order derivative UV spectrophotometry.  

PubMed

In this study, nimesulide which has been used as an analgesic, antipyretic and anti-inflammatory agent, was analyzed by using second order derivative UV spectrophotometry. The solvent, the degree of derivation, ranges of wavelength and n-value were chosen in order to optimize the conditions. The concentration of nimesulide in its solutions in ethanol and chloroform were determined between the wavelength ranges of 200 and 500 nm (n = 6, delta lambda = 21) and in the linearity ranges of 2.0-90.0 microg ml(-1) in ethanol and 2.0-50.0 microg ml(-1) in chloroform by using the values obtained from the second derivative UV spectrum of the substance. The developed second derivative UV spectrophotometric method was applied to the pharmaceutical preparations such as tablet, sachet (granule) and suspension. Tablet and sachet were analysed in ethanol while the suspension was analysed in chloroform. The results obtained from derivative UV spectrophotometry were compared with those obtained by using HPLC. It was found that the difference was not statistically important between these methods. It was concluded that developed derivative UV spectrophotometric method was accurate, sensitive, precise, reproducible and could be applied directly and easily to the pharmaceutical preparations. PMID:10727137

Altinöz, S; Dursun, O O

2000-02-01

315

A new catalytic-spectrophotometric method for quantification of trace amounts of nitrite in fruit juice samples.  

PubMed

A new kinetic method has been developed for the determination of nitrite in fruit juice samples. The method is based on the catalytic effect of nitrite with the oxidation of Nile Blue A (NBA) by KBrO(3) in the sulfuric acid medium. The optimum conditions obtained are 1.2 mM sulfuric acid, 0.034 mM of NBA, 2.8?×?10(-3) M KBrO(3), reaction temperature of 20 °C, and reaction time of 100 s at 595.5 nm. Under the optimized conditions, the method allowed the quantification of nitrite in a range of 0.2-800 ?g/mL with a detection limit of 0.02 ?g/mL. The method was applied to the determination of nitrite in 15 brands of fruit juice samples. PMID:22797881

Sobhanardakani, S; Farmany, A; Abbasi, S; Cheraghi, J; Hushmandfar, R

2013-03-01

316

Comparison of infrared spectrophotometric and lead salt-alcohol methods for determination of trans octadecenoic acids and esters  

Microsoft Academic Search

Summary  The scope and limitations of the lead salt-alcohol method (11, 19) have been defined as a result of observations in the authors'\\u000a laboratories and in others. Trans octadecenoic acids and esters are not determined specifically by this method, and when large\\u000a amounts of cis acids or esters are present, they are also isolated with the solid acid fraction.\\u000a \\u000a The infrared

Daniel Swern; H. B. Knight; O. D. Shreve; M. R. Heether

1950-01-01

317

Determination of oil-in-water using nanoemulsions as solvents and UV visible and total organic carbon detection methods.  

PubMed

The aim of this study was to investigate the application of oil in water (O/W) nanoemulsion as solvent in the extraction step for determination of oil content in oily water, measured using a UV visible spectrophotometer (UV-vis) and a total organic carbon (TOC) analyzer. The optical micrographs and distribution size curves showed that the use of a small amount of nanoemulsion was capable of transforming the oily water in a colloidal dispersion that can be read in the UV-vis and TOC-VCHS devices. The oil content results obtained showed great accuracy between the measurements, with very low average standard deviation (?5%) for both UV-vis and TOC-VCHS. The new methods suggested in this work are very promising, since they allow simple, quick and accurate analyses, and especially require a lower volume of solvent (less than 1%) compared to those used in conventional analytic methods. PMID:23598227

Costa, Josane A; Farias, Naiara C; Queirós, Yure G C; Mansur, Claudia R E

2013-03-30

318

Spectrophotometric determination of labetalol in pharmaceutical preparations and spiked human urine  

Microsoft Academic Search

Two simple and sensitive spectrophotometric methods were developed for the spectrophotometric determination of labetaolol (LBT). Both methods are based on the phenolic nature of the drug. The first method (Method I) is based on coupling LBT with diazotized benzocaine in presence of trimethylamine. A yellow colour peaking at 410 nm was produced and its absorbance is linear with the concentration

F. Belal; S. Al-Shaboury; A. S. Al-Tamra

2003-01-01

319

General Subject 1. Report to ICUMSA on the determination of commercial alpha-amylase activity by a spectrophotometric method  

Technology Transfer Automated Retrieval System (TEKTRAN)

A report is given on a new industrial method for the determination of the activity or strength of commercial alpha-amylase at a sugarcane factory or refinery, as well as a recommendation. At the present time, the activities or strengths of commercial alpha-amylases cannot be directly compared becau...

320

Simultaneous determination of moexipril hydrochloride and hydrochlorothiazide in tablets by derivative spectrophotometric and high-performance liquid chromatographic methods.  

PubMed

Two new simple and selective assay methods have been presented for the binary mixtures of moexipril hydrochloride (MOEX) and hydrochlorothiazide (HCTZ) in pharmaceutical formulations. The first method depends on second-derivative ultraviolet spectrophotometry with zero-crossing measurements at 215 and 234 nm for MOEX and HCTZ, respectively. The assay was linear over the concentration ranges 1.0-11.0 microg ml(-1) for MOEX and 0.5-9.0 microg ml(-1) for HCTZ. The determination limits for MOEX and HCTZ were found to be 1.0 and 0.5 microg ml(-1), respectively; while the detection limits were 0.2 microg ml(-1) for MOEX and 0.1 microg ml(-1) for HCTZ. The second method was based on isocratic reversed-phase liquid chromatography by using a mobile phase acetonitrile-20 mM phosphate buffer (pH 4.0) (50:50, v/v). Lisinopril was used as an internal standard (IS) and the substances were detected at 212 nm. The linearity range for both drugs was 0.5-12.0 microg ml(-1). The determination and detection limits were found to be 0.100 and 0.010 microg ml(-1) for MOEX and 0.025 and 0.005 microg ml(-1) for HCTZ, respectively. The proposed methods were successfully applied to the determination of these drugs in synthetic mixtures and commercially available tablets with a high percentage recovery, good accuracy and precision. PMID:14550868

Ertürk, Sidika; Cetin, Sevil Müge; Atmaca, Sedef

2003-10-15

321

Spectrophotometric titration of zirconium in siliceous materials.  

PubMed

An accurate and selective complexometric titration procedure based upon a spectrophotometrically detected end-point has been developed for the determination of zirconium in glasses, glass-ceramics and refractories. A p-bromomandelic acid separation step for zirconium imparts excellent selectivity to the procedure. The method is particularly important for the 1-5% concentration range where a simple, accurate and selective method for the determination of zirconium has been lacking. PMID:18962344

Sugawara, K F; Su, Y S; Strzegowski, W R

322

A Simple and Selective Spectrophotometric Method for the Determination of Trace Gold in Real, Environmental, Biological, Geological and Soil Samples Using Bis (Salicylaldehyde) Orthophenylenediamine  

PubMed Central

A simple high sensitive, selective, and rapid spectrophotometric method for the determination of trace gold based on the rapid reaction of gold(III) with bis(salicylaldehyde)orthophenylenediamine (BSOPD) in aqueous and micellar media has been developed. BSOPD reacts with gold(III) in slightly acidic solution to form a 1:1 brownish-yellow complex, which has an maximum absorption peak at 490 nm in both aqueous and micellar media. The most remarkable point of this method is that the molar absorptivities of the gold-BSOPD complex form in the presence of the nonionic TritonX-100 surfactant are almost a 10 times higher than the value observed in the aqueous solution, resulting in an increase in the sensitivity and selectivity of the method. The apparent molar absorptivities were found to be 2.3 × 104 L mol?1 cm?1 and 2.5 × 105 L mol?1 cm?1 in aqueous and micellar media, respectively. The reaction is instantaneous and the maximum absorbance was obtained after 10 min at 490 nm and remains constant for over 24 h at room temperature. The linear calibration graphs were obtained for 0.1–30 mg L?1 and 0.01–30 mg L?1 of gold(III) in aqueous and surfactant media, respectively. The interference from over 50 cations, anions and complexing agents has been studied at 1 mg L?1 of Au(III); most metal ions can be tolerated in considerable amounts in aqueous micellar solutions. The Sandell’s sensitivity, the limit of detection and relative standard deviation (n = 9) were found to be 5 ng cm?2, 1 ng mL?1 and 2%, respectively in aqueous micellar solutions. Its sensitivity and selectivity are remarkably higher than that of other reagents in the literature. The proposed method was successfully used in the determination of gold in several standard reference materials (alloys and steels), environmental water samples (potable and polluted), and biological samples (blood and urine), geological, soil and complex synthetic mixtures. The results obtained agree well with those samples analyzed by atomic absorption spectrophotometry (AAS). PMID:19609392

Soomro, Rubina; Ahmed, M. Jamaluddin; Memon, Najma; Khan, Humaira

2008-01-01

323

Simultaneous Kinetic Spectrophotometric Determination of Ascorbic Acid and L-Cysteine by H-Point Standard Addition Method  

Microsoft Academic Search

The H-point standard addition method (HPSAM) is applied to kinetic data for the simultaneous determination of ascorbic acid (AA) and L-cysteine (Cys). If present in excess amounts, iron(III) is quantitatively reduced to iron(II) by AA or Cys which in turn, in the presence of phenanthroline (phen), produces a colored iron(II)-phen complex showing maximum absorbance at 510?nm. HPSAM is based on

Jahanbakhsh Ghasemi; Soodabe Seifi; Mozafar Sharifi; Rostam Ghorbani; Ali Amini

2004-01-01

324

Simultaneous spectrophotometric determination of valsartan and hydrochlorothiazide by H-point standard addition method and partial least squares regression.  

PubMed

Simultaneous determination of valsartan and hydrochlorothiazide by the H-point standard additions method (HPSAM) and partial least squares (PLS) calibration is described. Absorbances at a pair of wavelengths, 216 and 228 nm, were monitored with the addition of standard solutions of valsartan. Results of applying HPSAM showed that valsartan and hydrochlorothiazide can be determined simultaneously at concentration ratios varying from 20:1 to 1:15 in a mixed sample. The proposed PLS method does not require chemical separation and spectral graphical procedures for quantitative resolution of mixtures containing the titled compounds. The calibration model was based on absorption spectra in the 200-350 nm range for 25 different mixtures of valsartan and hydrochlorothiazide. Calibration matrices contained 0.5-3 ?g mL-1 of both valsartan and hydrochlorothiazide. The standard error of prediction (SEP) for valsartan and hydrochlorothiazide was 0.020 and 0.038 ?g mL-1, respectively. Both proposed methods were successfully applied to the determination of valsartan and hydrochlorothiazide in several synthetic and real matrix samples. PMID:21406342

Lakshmi, Karunanidhi Santhana; Lakshmi, Sivasubramanian

2011-03-01

325

Application of principal component-artificial neural network models for simultaneous determination of phenolic compounds by a kinetic spectrophotometric method.  

PubMed

A multicomponent analysis method based on principal component analysis-artificial neural network models (PC-ANN) is proposed for the determination of phenolic compounds. The method relies on the oxidative coupling of phenols (phenol, 2 chlorophenol, 3-chlorophenol and 4-chlorophenol) to N,N-diethyl-p-phenylenediamine in the presence of hexacyanoferrate(III). The reaction monitored at analytical wavelength 680 nm of the dye formed. Phenols can be determined individually over the concentration range 0.1-7.0 microg ml(-1). Differences in the kinetic behavior of the four species were exploited by using PC-ANN, to resolve mixtures of phenol. After reducing the number of kinetic data using principal component analysis, an artificial neural network consisting of three layers of nodes was trained by applying a back-propagation learning rule. The optimized ANN allows the simultaneous quantitation of four analytes in mixtures with relative standard errors of prediction in the region of 5% for four species. The results show that PC-ANN is an efficient method for prediction of the four analytes. PMID:18272286

Hasani, Masoumeh; Moloudi, Mahsa

2008-08-30

326

Micellar HPLC and derivative spectrophotometric methods for the simultaneous determination of fluconazole and tinidazole in pharmaceuticals and biological fluids.  

PubMed

Micellar high-performance liquid chromatography (HPLC) and first-derivative ultraviolet spectrophotometry were used to simultaneously determine fluconazole (FLZ) and tinidazole (TNZ) in combined pharmaceutical dosage forms. The derivative procedure is based on the linear relationship between the drug concentration and the first derivative amplitudes at 220 and 288 nm for FLZ and TNZ, respectively. The calibration graphs were linear in the range of 1.5-9.0 µg/mL for FLZ and 10.0-60.0 µg/mL for TNZ. Furthermore, an HPLC procedure with ultraviolet detection at 210 nm was developed. For the HPLC procedure, good chromatographic separation was achieved using an ODS C18 column (250 × 4.6 mm i.d.). The mobile phase containing 0.15M sodium dodecyl sulphate, 0.3% triethylamine and 12% n-propanol in 0.02M orthophosphoric acid at pH 5.5 was pumped at a flow rate of 1 mL/min. Indapamide was used as an internal standard. The method showed good linearity over the concentration ranges of 1.5-30.0 and 10.0-200.0 µg/mL, with limits of detection of 0.36 and 2.70 µg/mL and limits of quantification of 1.1 and 8.2 µg/mL for FLZ and TNZ, respectively. The suggested methods were successfully applied for the simultaneous analysis of the drugs in their laboratory prepared mixture, co-formulated tablet and single dosage forms. Moreover the second method was also extended to the determination of the drugs in biological fluids. PMID:23568958

Belal, F; Sharaf El-Din, M K; Eid, M I; El-Gamal, R M

2014-04-01

327

A vacuum ultraviolet spectrophotometric system  

NASA Technical Reports Server (NTRS)

The development of a vacuum ultraviolet spectrophotometric system for measuring transmittance and reflectance at variable angles is presented. Using various detectors and sources, the spectrophotometric system has been used for wavelengths from 80 nm to 300 nm with optical components up to 80 mm in diameter. The capability exists to make measurements through the visible range.

Spann, James F.; Keffer, Charles E.; Zukic, Muamer

1993-01-01

328

UV-visible spectroscopy as an alternative to liquid chromatography for determination of everolimus in surfactant-containing dissolution media: a useful approach based on solid-phase extraction.  

PubMed

High-throughput 96-well solid phase extraction (SPE) plate with C-18 reversed phase sorbent followed by UV-visible (UV-Vis) microplate reader was applied to the analysis of hydrophobic drugs in surfactant-containing dissolution media, which are often used to evaluate the in-vitro drug release of drug eluting stents (DES). Everolimus and dissolution medium containing Triton X-405 were selected as representatives, and the appropriate SPE conditions (adsorption, washing and elution) were investigated to obtain a practical and reliable sample clean-up. It was shown that the developed SPE procedure was capable of removing interfering components (Triton X-405 and its impurities), allowing for an accurate automated spectrophotometric analysis to be performed. The proposed UV-Vis spectrophotometric method yielded equivalent results compared to a classical LC analysis method. Linear regression analysis indicated that both methods have the ability to obtain test results that are directly proportional to the concentration of analyte in the sample within the selected range of 1.0-10 ?g/ml for everolimus, with a coefficient of correlation (r(2)) value of >0.998 and standard deviation of the residuals (Syx) of <2%. The individual recoveries of everolimus ranged from 97 to 104% for the UV-Vis spectrophotometric method and from 98 to 102 for the HPLC method, respectively. The 95% CI of the mean recovery for the UV-Vis spectrophotometric method was 99-102% and for the HPLC method was 99-101%. No statistical difference was found between the mean recoveries of the methods (p=0.42). Hence the methods are free from interference due to Triton and other chemicals present in the dissolution medium. The variation in the amount of everolimus estimated by UV-Vis spectrophotometric and HPLC methods was ?3.5%, and the drug release profiles obtained by both methods were found to be equivalent by evaluation with two-one-sided t-test (two-tailed, p=0.62; mean of differences, 0.17; 95% CI, 0.62-0.96) and similarity factor f2 (f2 value, 87). The excellent conformity of the results makes UV-Vis spectrophotometer an ideal tool for analyzing the drugs in the media containing surfactants, after SPE. The 96-well SPE plates in combination with UV-Vis microplate reader provide a high throughput method for the determination of in-vitro drug release profile of DES. Switching from HPLC to UV-Vis spectrophotometer microplate reader assay reduces the solvent consumption and labor required for the sample analyses. This directly impacts the profitability of the laboratory. PMID:22726455

Kamberi, Marika; Tran, Thu-Ngoc

2012-11-01

329

Quantitation of serrapeptase in formulations by UV method in the microplate format.  

PubMed

Serrapeptase is an anti-inflammatory, proteolytic enzyme isolated from the microorganism, Serratia sp. HY-6. Very few methods are available for the quantification of serrapeptase. The activity of the enzyme is determined by an ELISA assay, colorimetric method using casein as substrate or by HPLC method. These methods are lengthy, time consuming and require a number of reagents and solvents. Therefore an attempt was made to develop a simple alternative method for regular estimation of drug in formulations. Serrapeptase enzyme was estimated in formulations by using microplate readers which uses the principle of vertical photometry. Further this method was validated and the robustness of this method was checked by estimating the drug in various formulations including liposomes and marketed tablet formulations. A linear relationship between drug concentration and absorbance was observed between 1-4 microg/ml at 230 nm (R(2)=0.9911). The percentage recovery values of the drug in serrapeptase liposomes were found to lie within the standard limit (97-98%) which confirms the method is accurate and free from any positive or negative interference of the excipient. The low value of standard deviation obtained confirms the precision of the method. (+/-0.020 - +/-0.044). The drug content values in marketed tablets values obtained matched the label claim. The proposed microplate UV-method for determination of serrapeptase in formulations is novel, simple, inexpensive, fast, specific and robust. Thus this method could be a better alternative for regular estimation of drug in the various marketed formulations of serrapeptase. PMID:18855600

Sandhya, K V; Devi, S Gayathri; Mathew, Sam T

2008-10-01

330

A novel spectrophotometric method for the determination of aminophylline in pharmaceutical samples in the presence of methanol  

NASA Astrophysics Data System (ADS)

A rapid, simple and sensitive method for the determination of aminophylline (Ami) using sodium 1, 2-naphthoquine-4-sulfonate (NQS) and methanol is established in this paper. It is based on the fact that a russety product can be formed by the reaction between aminophylline (Ami) and sodium 1, 2-naphthoquine-4-sulfonate (NQS) in pH 13.00 buffer solution. When methanol is added to the solution, the sensitivity of the color development reaction between Ami and NQS is improved, and the color of the system of NQS-Ami becomes a salmon pink. Beer's law is obeyed in a range of 4.97-69.5 ?g ml -1 of Ami at the maximum absorption of 453 nm ( ? = 4.87 × 10 3 l mol -1 cm -1). The linear regression equation of the calibration curve is A = 0.14458 + 0.00832 C (?g ml -1), with a linear regression correlation coefficient of 0.9944. The detection limit is 0.7 ?g ml -1 (3 ?/ k), R.S.D. is 1.1% and the recovery rate is in range of 92.5-105%. Furthermore, this method has been successfully applied to the determination of Ami in pharmaceutical samples.

Li, Quanmin; Zhang, Huanhuan

2008-07-01

331

Spectrophotometric study of asteroids  

NASA Technical Reports Server (NTRS)

Observations of particular faint asteroids of interest, in particular the Trojans, were carried out during an observation run at Kitt Peak National Observatory (1.3 meter telescope) in September 1973, and an attempt was made to study the compositional variation within Hirayama families. A particularly important study was initiated to observe spectrophotometrically certain asteroids which are considered as potential source bodies for meteorites. A program was also undertaken to coordinate the spectrophotometry program with polarimetric and thermal-infrared observation programs being conducted elsewhere.

Chapman, C. R.

1974-01-01

332

Spectral absorbance of benthic cladoceran carapaces as a new method for inferring past UV exposure of aquatic biota  

NASA Astrophysics Data System (ADS)

We developed a method for measuring fossil cladoceran (Branchiopoda) carapace absorbance to infer past ultraviolet radiation (UV) exposure in lakes. This was done under the presumptions that cladocerans synthesize photoprotective compounds, of which melanin is the main UV-absorbing pigment, to their exoskeletons and melanin is preserved in sedimentary cladoceran remains. We extracted large-sized cladoceran (benthic Alona spp.) carapaces from subsections of sediment cores from two environmentally divergent lakes; a humic boreal forest lake in eastern Finland (past 1500 years) and a clear-water mountain lake in the Austrian Alps (past 300 years). We measured the absorbance of extracted carapaces with a spectrophotometer under visible light and UV wavelengths using an adapter, which was designed to hold the microfossils. When compared to the spectrum of synthetic melanin, the shapes of absorbance spectra at the 700-280 nm range suggested that the fossil carapaces contained melanin. The carapace absorbance under UV throughout the sediment cores was significantly higher in the clear-water alpine lake than in the humic boreal lake reflecting differences in the general underwater UV and optical environments between the sites. In addition, carapace absorbance was significantly higher during the Little Ice Age (LIA) than during pre- or post-LIA periods in both lakes. In the alpine lake, this was most likely a response to increased underwater UV induced by reduced primary production and more transparent water column during the cold summers of LIA, whereas reduced input of carbon compounds from the catchment through elongated permafrost and ice-cover periods likely induced higher water transparency in the boreal lake during this cold climate phase. We conclude that fossil melanin provides a good estimation of past underwater UV exposure in lakes with large cladoceran carapaces preserved in sediments and that the method introduced here is easy and cost- and time-efficient technique to be widely used in paleoaquatic UV inferences.

Nevalainen, Liisa; Rautio, Milla

2014-01-01

333

Review of UV spectroscopic, chromatographic, and electrophoretic methods for the cholinesterase reactivating antidote pralidoxime (2-PAM).  

PubMed

Pralidoxime (2-PAM) belongs to the class of monopyridinium oximes with reactivating potency on cholinesterases inhibited by phosphylating organophosphorus compounds (OPC), for example, pesticides and nerve agents. 2-PAM represents an established antidote for the therapy of anticholinesterase poisoning since the late 1950s. Quite high therapeutic concentrations in human plasma (about 13?µg/ml) lead to concentrations in urine being about 100 times higher allowing the use of less sensitive analytical techniques that were used especially in the early years after 2-PAM was introduced. In this time (mid-1950s until the end of the 1970s) 2-PAM was most often analyzed by either paper chromatography or simple UV spectroscopic techniques omitting any sample separation step. These methods were displaced completely after the establishment of column liquid chromatography in the early 1980s. Since then, diverse techniques including cation exchange, size-exclusion, reversed-phase, and ligand-exchange chromatography have been introduced. Today, the most popular method for 2-PAM quantification is ion pair chromatography often combined with UV detection representing more than 50% of all column chromatographic procedures published. Furthermore, electrophoretic approaches by paper and capillary zone electrophoresis have been successfully used but are seldom applied. This review provides a commentary and exhaustive summary of analytical techniques applied to detect 2-PAM in pharmaceutical formulations and biological samples to characterize stability and pharmacokinetics as well as decomposition and biotransformation products. Separation techniques as well as diverse detectors are discussed in appropriate detail allowing comparison of individual preferences and limitations. In addition, novel data on mass spectrometric fragmentation of 2-PAM are provided. PMID:21953823

John, Harald; Blum, Marc-Michael

2012-01-01

334

Degradation Study on Sulfasalazine and a Validated HPLC-UV Method for its Stability Testing  

PubMed Central

Sulfasalazine (SSZ) was subjected to degradation under the conditions of hydrolysis (acid, alkali, and water), oxidation (30% H2O2), dry heat, and photolysis (UV-VIS light) in accordance with the ICH guidelines. An RP-HPLC method was developed to study the degradation behavior. No degradation was noted under any condition except alkaline hydrolysis where SSZ was degraded to a single minor product. SSZ was optimally resolved from this product on an XTerra® RP18 column with a mobile phase composed of methanol and an ammonium acetate buffer (10 mM, pH 7.0) (48:52, v/v) delivered at a rate of 0.8 mL/min in an isocratic mode. The method was validated and found to be linear (r2=0.99945), precise (%RSD <2), robust, and accurate (94–102%) in the concentration range of 0.5–50 ?g/mL of SSZ. The PDA analysis of the degraded sample revealed the SSZ peak purity to be 998.99 and the drug peak eluted with a resolution factor of >2 from the nearest resolving peak, indicating the method to be selectively stability-indicating for the drug analysis. The method was applied successfully for the stability testing of the commercially available SSZ tablets that were under varied ICH-prescribed conditions. An explanation for the unusual stability of the drug when exposed to acidic hydrolysis, despite the presence of the sulfonamide linkage, is also discussed. PMID:24959403

Saini, Balraj; Bansal, Gulshan

2014-01-01

335

Degradation Study on Sulfasalazine and a Validated HPLC-UV Method for its Stability Testing.  

PubMed

Sulfasalazine (SSZ) was subjected to degradation under the conditions of hydrolysis (acid, alkali, and water), oxidation (30% H2O2), dry heat, and photolysis (UV-VIS light) in accordance with the ICH guidelines. An RP-HPLC method was developed to study the degradation behavior. No degradation was noted under any condition except alkaline hydrolysis where SSZ was degraded to a single minor product. SSZ was optimally resolved from this product on an XTerra(®) RP18 column with a mobile phase composed of methanol and an ammonium acetate buffer (10 mM, pH 7.0) (48:52, v/v) delivered at a rate of 0.8 mL/min in an isocratic mode. The method was validated and found to be linear (r(2)=0.99945), precise (%RSD <2), robust, and accurate (94-102%) in the concentration range of 0.5-50 ?g/mL of SSZ. The PDA analysis of the degraded sample revealed the SSZ peak purity to be 998.99 and the drug peak eluted with a resolution factor of >2 from the nearest resolving peak, indicating the method to be selectively stability-indicating for the drug analysis. The method was applied successfully for the stability testing of the commercially available SSZ tablets that were under varied ICH-prescribed conditions. An explanation for the unusual stability of the drug when exposed to acidic hydrolysis, despite the presence of the sulfonamide linkage, is also discussed. PMID:24959403

Saini, Balraj; Bansal, Gulshan

2014-06-01

336

Spectrophotometric determination of codeine in pharmaceutical preparations  

Microsoft Academic Search

Two spectrophotometric methods are described for the determination of tiopronin in pharmaceuticals. They are based on the oxidation-reduction reaction between tiopronin and iron (III), then forming a complex between iron (II) and ferrozine or di-2-pyridyl ketone-2-thiophenoylhydrazone. The produced colored iron (II)-ferrozine complex (system I) absorbs at 562 nm, while the iron (II)-di-2-pyridyl ketone-2- thiophenoylhydrazone complex (system II) absorbs at 656

M. Jeliki?-Stankov; D. Veselinovi?; Z. Koricanac; T. Jovanovic

1981-01-01

337

Rapid spectrophotometric determination of red and yellow isochromic carotenoid fractions in paprika and red pepper oleoresins.  

PubMed

A rapid method has been developed for the determination of the red (R) and yellow (Y) isochromic carotenoid pigments fractions in paprika and oleoresins, based on UV-visible spectrophotometric measurement at two characteristic wavelengths and application of the Lambert-Beer law for multicomponent mixtures. The wavelengths 472 and 508 nm were selected as the most appropriate for simultaneous quantification of these fractions in the acetone extract of pigments. Experimental determination of the specific absorption coefficients (epsilon) for the two pigment fractions (R, Y) at 472 and 508 nm yielded equations to calculate the concentration of the two fractions, the total pigment content, and the ratio between the two fractions. The error in the determination of the isochromic fractions by the proposed spectrophotometric method was <5% when the results were compared with those obtained by HPLC analysis. The method can be applied to the direct extract of pigments, thereby avoiding saponification and minimizing errors from pigment degradation and sample manipulation as well as shortening the time of analysis (5 min in the case of oleoresins). PMID:11513632

Hornero-Méndez, D; Mínguez-Mosquera, M I

2001-08-01

338

Spectrophotometric determination of Metronidazole and Secnidazole in pharmaceutical preparations based on the formation of dyes  

Microsoft Academic Search

A rapid and sensitive spectrophotometric method is proposed for determination of Metronidazole and Secnidazole. The method depends on the reduction of Metronidazole and Secnidazole molecule with zinc dust and hydrochloric acid flowed by diazotization and coupling with ?-naphtol to give red colored chromogens easily measured spectrophotometrically which has ?max=510nm. The experimental conditions were optimized and Berr's law was obeyed over

T. Saffaj; M. Charrouf; A. Abourriche; Y. Aboud; A. Bennamara; M. Berrada

2006-01-01

339

TLC-UV densitometric and GC-MSD methods for simultaneous quantification of morphine and codeine in poppy capsules.  

PubMed

Thin-layer chromatographic (TLC)-UV densitometric and gas-chromatographic-mass spectrometric detection (GC-MSD) methods were developed for simultaneous quantification of morphine and codeine in poppy capsules (Papaver somniferum). Morphine and codeine were isolated by extraction with chloroform: isopropanol (3:1, v/v) at pH = 8.5 and by solid-phase extraction on Snap-Cap cartridges at pH = 8.5. The TLC-UV densitometric quantification was performed by external standard method on silica gel plates using ethyl acetate: toluene: methanol: ammonia (68:17:10:5, v/v) as developing solvent and UV detection at 275 nm. For the GC-MSD analysis, the drugs were derivatized with acetic anhydride: pyridine (1:1, v/v) and separated on a 30 m HP5 capillary column. The quantification was performed using nalorphine as internal standard. PMID:9919965

Popa, D S; Oprean, R; Curea, E; Preda, N

1998-12-01

340

A simple spectrophotometric method for the determination of phosphate in soil, detergents, water, bone and food samples through the formation of phosphomolybdate complex followed by its reduction with thiourea  

NASA Astrophysics Data System (ADS)

A simple spectrophotometric method is developed here for the determination of phosphate present in the samples of soil, detergents, water, bone and food based on the formation of phosphomolybdate complex with the added molybdate followed by the reduction of the complex with thiourea in aqueous sulfuric acid medium. The system obeys Beer's law at 840 nm in the phosphate concentration range, 0.5-10.0 ?g/ml. Molar absorptivity, correlation coefficient and Sandell's sensitivity values are found to be 1.712 mol -1 cm -1, 0.9769 and 0.0555 ?g cm -2 respectively. For a comparison of the results determined from the developed method, phosphate present in the same set of samples is determined separately following an official method. The results of the developed method are agreeing well with those of the official phosphomolybdate method.

Shyla, B.; Mahadevaiah; Nagendrappa, G.

2011-01-01

341

Validated stability-indicating HPLC-UV method for simultaneous determination of glipizide and four impurities.  

PubMed

A selective stability-indicating HPLC-UV method for simultaneous determination of glipizide and four impurities (DPs I-IV) formed under hydrolytic conditions was developed and validated. The drug and impurities were resolved on an XTerra C18 column (250 x 4.5 mm id) in a single gradient run using buffer (0.005 M KH2PO4; pH 3.0)-methanol (60 + 40, v/v; mobile phase A) and (20 + 80, v/v; mobile phase B) at a flow rate of 0.5 mL/min with 230 nm detection wavelength. The method was linear across concentration ranges of 0.2-100, 0.1-100, 0.5-100, 0.2-100, and 0.1-50 microg/mL for glipizide and DPs I-IV, respectively. The RSD for intraday and interday precision for the drug and impurities was < 1 and < 1.2%, respectively. Satisfactory recoveries (96.58-99.97%) of each of the three concentrations selected across the linearity range of each analyte were obtained, proving the method was sufficiently accurate. The LOD was 0.07, 0.05, 0.16, 0.08, and 0.05 microg/mL and the LOQ was 0.20, 0.14, 0.50, 0.23, and 0.14 microg/mL for the drug and DPs I-IV, respectively. Each peak was resolved with resolution of > 2 from the nearest peak. Insignificant changes in retention time (< 4%) and calculated amount (< 1.65%) of drug and each impurity upon small but deliberate changes in various chromatographic parameters were observed, suggesting the method was robust. The method was applied successfully to stability testing of glipizide tablets. PMID:21563686

Gupta, Sakshi; Bansal, Gulshan

2011-01-01

342

Determination of capsaicinoids in habanero peppers by chemometric analysis of UV spectral data.  

PubMed

A novel spectrophotometric method for the determination of capsaicinoids in habanero pepper extracts is described that does not require prior analyte separation. The method uses partial-least-squares (PLS-1) multivariate regression modeling techniques in conjunction with ordinary UV absorption spectral data obtained on alcoholic extracts of habanero peppers (Capsicum chinese). The PLS-1 regression models were developed by correlating the known total concentration of the two major capsaicinoids (capsaicin and dihydrocapsaicin) in the extracts as determined by high-performance liquid chromatography with the spectral data. The regression models were subsequently validated with laboratory-prepared test sets. The validation studies revealed that the root-mean-square error of prediction varied from 4 to 8 ppm, based on the results obtained from models prepared from nine test sets. Once a regression model has been developed and validated, analyses of the extracts can be accomplished rapidly by ordinary spectrophotometric procedures without any prior separation steps. PMID:17608494

Davis, Christopher B; Markey, Carolyn E; Busch, Marianna A; Busch, Kenneth W

2007-07-25

343

Spectrophotometric Estimation of Risperidone in Tablets  

PubMed Central

A simple, rapid and highly sensitive spectrophotometric method is developed for the determination of risperidone in tablet formulation. The method is based on the oxidation of drug using potassium permanganate in alkaline medium and excess potassium permanganate oxidizes 1,10-phenanthroline Fe(II). The measurement of decrease in absorbance of 1,10-phenanthroline Fe (II) was done at 415 nm. The beer's law is obeyed in the concentration range of 5.0 to 40.0 ?g/ml and molar absorptivity is found to be 7.3932 × 104 l/mol/cm. The proposed method is well suited for the pharmaceutical formulations. PMID:25425761

Jayanna, B. K.; Devaraj, T. D.; Roopa, K. P.; Nagendrappa, G.; Kumar, H. R. Arun; Gowda, N.

2014-01-01

344

Determination of sotolon content in South African white wines by two novel HPLC-UV and UPLC-MS methods.  

PubMed

Sotolon has been reported to play an important role in the atypical ageing and aroma character of many wines. A number of analytical techniques for sotolon analysis in wine have been reported, but these often require extensive sample preparation. In this work we report a HPLC-UV method and a novel UPLC-MS method to determine sotolon concentrations in white wines with little sample preparation applied for the first time for the evaluation of sotolon levels in South African wines. The validation showed that the instrumental methods had good accuracy, repeatability and linearity, but the UPLC-MS method proved more sensitive. For both methods, quantification limits were lower than the sotolon odour threshold in wine (10?g/L), 0.86?g/L and 0.013?g/L, for HPLC-UV and UPLC-MS methods, respectively. Sotolon levels in 65 South African white wines were often found to be lower than the reported odour threshold, with the highest concentration being 9.11?g/L. However, for low levels (<1?g/L), unknown interferences in certain wines led to sotolon not being quantified with the HPLC-UV method, which made the UPLC-MS method more suitable. PMID:25236214

Gabrielli, Mario; Buica, Astrid; Fracassetti, Daniela; Stander, Marietjie; Tirelli, Antonio; du Toit, Wessel J

2015-02-15

345

Determination of Cephalexin Monohydrate in Pharmaceutical Dosage Form by Stability-Indicating RP-UFLC and UV Spectroscopic Methods  

PubMed Central

An ultra-fast liquid chromatographic method and two UV spectroscopic methods were developed for the determination of cephalexin monohydrate in pharmaceutical dosage forms. Isocratic separation was performed on an Enable C18G column (250 mm × 4.6 mm i.d., 5 ?m) using methanol:0.01 M TBAHS (50:50, v/v) as the mobile phase at a flow rate of 1.0 ml/min. The PDA detection wavelength was set at 254 nm. The UV spectroscopic method was performed at 261 nm and at 256–266 nm for the AUC method using a phosphate buffer (pH=5.5). The linearity was observed over a concentration range of 1.0–120 ?g/ml for UFLC and both of the UV spectroscopic methods (correlation coefficient=0.999). The developed methods were validated according to ICH guidelines. The relative standard deviation values for the intraday and interday precision studies were < 2%, and the accuracy was > 99% for all of the three methods. The developed methods were used successfully for the determination of cephalexin in dry syrup formulation. PMID:24482771

Panda, Sagar Suman; Ravi Kumar, Bera V. V.; Dash, Rabisankar; Mohanta, Ganeswar

2013-01-01

346

Simultaneous spectrophotometric determination of trace amounts of uranium, thorium, and zirconium using the partial least squares method after their preconcentration by alpha-benzoin oxime modified Amberlite XAD-2000 resin.  

PubMed

A new solid phase extraction method for separation and preconcentration of trace amounts of uranium, thorium, and zirconium in water samples is proposed. The procedure is based on the adsorption of U(VI), Th(IV) and Zr(IV) ions on a column of Amberlite XAD-2000 resin loaded with alpha-benzoin oxime prior to their simultaneous spectrophotometric determination with Arsenazo III using orthogonal signal correction partial least squares method. The enrichment factor for preconcentration of uranium, thorium, and zirconium was found to be 100. The detection limits for U(VI), Th(IV) and Zr(IV) were 0.50, 0.54, and 0.48microgL(-1), respectively. The precision of the method, evaluated as the relative standard deviation obtained by analyzing a series of 10 replicates, was below 4% for all elements. The practical applicability of the developed sorbent was examined using synthetic seawater, natural waters and ceramic samples. PMID:20006073

Ghasemi, Jahan B; Zolfonoun, E

2010-01-15

347

Spectrophotometric determination of pentaerythritol tetranitrate in tablets.  

PubMed

A sensitive spectrophotometric method is reported for the quantitative determination of pentaerythritol tetranitrate in tablets. The method is based on reduction of pentaerythritol tetranitrate with zinc and calcium chloride, and reaction of the nitroso compound thus formed with 1-naphthylamine in acidic medium. The reaction gives a purple product having an absorbance maximum at 545 nm. Beer's law is obeyed in the concentration range of 1-10 micrograms/mL of reaction mixture. The presence of meprobamate in tablets does not interfere with the proposed analytical determination. PMID:6520087

Shingbal, D M; Agni, R M

1984-01-01

348

The winds of O-stars. I - An analysis of the UV line profiles with the SEI method  

NASA Technical Reports Server (NTRS)

The theoretical UV P Cygni profiles of the UV resonance lines for C IV, N V, Si IV, C III, and N IV of 26 O-type stars and one B star were calculated using the SEI method described by Lamers et al. (1987), taking into account the effects of turbulence in the wind, limb darkening, photospheric lines, and interstellar Ly alpha. The results were compared with profiles observed with the IUE satellite. The profile fits were found to be very accurate, showing significant improvement over previously obtained fits with the Sobolev (1958) method. The SEI method and the line fitting analysis are described and the results are presented in terms of the column densities and distributions of absorbing atoms, and the velocity laws.

Groenewegen, M. A. T.; Lamers, H. J. G. L. M.

1989-01-01

349

UV-Visible Spectroscopic Method and Models for Assessment and Monitoring of Harmful Algal Blooms  

NASA Technical Reports Server (NTRS)

The development of an enhanced predictive and early warning capability for the occurrence and impact of harmful algal blooms (HABs) would be of great benefit to coastal communities. A critical issue for early detection and monitoring of HABs is the need to detect harmful algal species within a mixed-species phytoplankton assemblage. Possession of UV-absorbing compounds called mycosporine-like amino acids (MAAs) may be one factor that allows HAB species to out-compete their phytoplankton neighbors. Possession of MAAs, which we believe can be inferred from strong UV-absorption signals in phytoplankton absorption coefficients, can be used as a flag for potential HAB outbreak. The goal of this project was to develop a solar simulating UV-visible incubator to grow HAB dinoflagellates, to begin MAA analysis of samples collected on global cruises, and to carry out initial experiments on HAB dinoflagellate species in pure culture. Our scientific objectives are to quantify MAA production and spectral induction mechanisms in HAB species, to characterize spectral absorption of MAAs, and to define the ecological benefit of MAAs (i.e. photoprotection). Data collected on cruises to the global oceans will be used to parameterize phytoplankton absorption in the UV region, and this parameterization could be incorporated into existing models of seawater optical properties in the UV spectral region. Data collected in this project were used for graduate fellowship applications by Elizabeth Frame. She has been awarded an EPA STAR fellowship to continue the work initiated by this project.

Mitchell, B. Greg

2000-01-01

350

Two Methods for Retrieving UV Index for All Cloud Conditions from Sky Imager Products or Total SW Radiation Measurements  

SciTech Connect

In the present study, we assess the cloud effects on UV Index (UVI) and total solar radiation (TR) as a function of cloud cover estimations and sunny conditions (from sky imaging products) as well as of solar zenith angle (SZA). These analyses are undertaken for a southern-hemisphere mid-latitude site where a 10-years dataset is available. It is confirmed that clouds reduce TR more than UV, in particular for obscured Sun conditions, low cloud fraction (< 60%) and large SZA (> 60º). Similarly, clouds enhance TR more than UV, mainly for visible Sun conditions, large cloud fraction and large SZA. Two methods to estimate UVI are developed: 1) from sky imaging cloud cover and sunny conditions, and 2) from TR measurements. Both methods may be used in practical operational applications, although Method 2 shows overall the best performance, since TR allows accounting for cloud optical properties. The mean absolute differences of Method 2 estimations with respect to measured values are 0.17 UVI units (for 1-minute data) and 0.79 Standard Erythemal Dose (SED) units (for daily integrations). Method 1 shows less accurate results but it is still suitable to estimate UVI: mean absolute differences are 0.37 UVI units and 1.6 SED.

Badosa, Jordi; Calbo, J.; McKenzie, R. L.; Liley, Ben; Gonzalez, J. A.; Forgan, B. W.; Long, Charles N.

2014-07-01

351

Two methods for retrieving UV index for all cloud conditions from sky imager products or total SW radiation measurements.  

PubMed

Cloud effects on UV Index (UVI) and total solar radiation (TR) as a function of cloud cover and sunny conditions (from sky images) as well as of solar zenith angle (SZA) are assessed. These analyses are undertaken for a southern-hemisphere mid-latitude site where a 10-years dataset is available. It is confirmed that clouds reduce TR more than UV, in particular for obscured Sun conditions, low cloud fraction (<60%) and large SZA (>60°). Similarly, local short-time enhancement effects are stronger for TR than for UV, mainly for visible Sun conditions, large cloud fraction and large SZA. Two methods to estimate UVI are developed: (1) from sky imaging cloud cover and sunny conditions, and (2) from TR measurements. Both methods may be used in practical applications, although Method 2 shows overall the best performance, as TR allows considering cloud optical properties. The mean absolute (relative) differences of Method 2 estimations with respect to measured values are 0.17 UVI units (6.7%, for 1 min data) and 0.79 Standard Erythemal Dose (SED) units (3.9%, for daily integrations). Method 1 shows less accurate results but it is still suitable to estimate UVI: mean absolute differences are 0.37 UVI units (15%) and 1.6 SED (8.0%). PMID:24645969

Badosa, Jordi; Calbó, Josep; Mckenzie, Richard; Liley, Ben; González, Josep-Abel; Forgan, Bruce; Long, Charles N

2014-01-01

352

Simple spectrophotometric determination of cinnarizine in its dosage forms  

Microsoft Academic Search

A direct, extraction-free spectrophotometric method has been developed for the determination of cinnarizine in pharmaceutical preparations. The method is based on ion-pair formation between the drug and three acidic (sulphonphthalein) dyes; namely bromocresol green (BCG), bromocresol purple (BCP) and bromophenol blue (BPB) which induces an instantaneous bathochromic shift of the maximum in the drug spectrum. Conformity to Beer's law enabled

H. Abdine; F. Belal; N. Zoman

2002-01-01

353

Extractive spectrophotometric determination of some phenothiazine derivatives in pharmaceutical preparations  

Microsoft Academic Search

A simple, accurate, rapid and sensitive spectrophotometric method has been developed for the assay of six phenothiazine derivatives in bulk drug and their pharmaceutical preparations. The method is based on ion-pair complex reaction of phenothiazines with bromocresol green in aqueous acidic buffer. The chromogen, being extractable with chloroform, could be measured quantitatively at 420 nm. All variables were studied in

K Basavaiah; G Krishnamurthy

1998-01-01

354

Extractive spectrophotometric determination of ceterizine HCl in pharmaceutical preparations  

Microsoft Academic Search

Two simple, rapid and sensitive extractive spectrophotometric methods have been developed for the assay of ceterizine hydrochloride (CTZH) in bulk drug and in pharmaceutical preparations. These methods are based on the formation of chloroform soluble complexes between CTZH with bromocresol purple (BCP) or bromophenol blue (BPB) in Walpole buffer of pH 2.64 with an absorption maximum at 409 nm and

B. G Gowda; M. B Melwanki; J Seetharamappa

2001-01-01

355

Spectrophotometric determination of selenium by use of thionin  

Microsoft Academic Search

A simple, rapid, and sensitive spectrophotometric method has been developed for the determination of selenium in real samples of water, soil, plant materials, human hair, and synthetic cosmetic and in pharmaceutical preparations. The method is based on the reaction of selenium with potassium iodide in an acidic medium to liberate iodine. The liberated iodine bleaches the violet color of thionin,

H. Revanasiddappa; T. Kiran Kumar

2002-01-01

356

HPLC-MS\\/MS METHOD FOR THE PHARMACOKINETIC STUDY OF ITRACONAZOLE A LOW UV ABSORBABLE DRUG INVOLVING WISTAR RATS  

Microsoft Academic Search

A new LC-MS\\/MS method was developed for the estimation of itraconazole, a weak UV absorbing drug, in rat plasma using verapamil as the internal standard. Chromatographic separation was achieved on an Agilent Zorbax Eclipse XDB-C18 column (50 mm × 4.6 mm, 1.8µ) as a stationary phase. A mixture of methanol-10 Mm ammonium formate pH 4.0 (90:10, v\\/v) was used as a mobile phase. Plasma

J. Dharuman; M. Vsudhevan; T. Ajithlal; K. N. Somasekaran

2011-01-01

357

FORCED DEGRADATION AND PH STABILITY STUDIES OF LYSERGOL: AN ERGOLIC ALKALOID BY STABILITY INDICATING RP HPLC-UV METHOD  

Microsoft Academic Search

A simple HPLC-UV method was developed and validated for the analysis of lysergol, its stress degradation profile, and pH stability studies. Instrument used was Agilent HPLC 1120 autosampler with a C18 reversed phase column and a mobile phase comprised of methanol and water (1% acetic acid) with isocratic flow. Flow rate was kept constant at 1 mL\\/min throughout the experiment and

Shamama Javed; Kanchan Kohli; Mushir Ali

2012-01-01

358

Determination of total phenols in tea infusions, tomato and apple juice by terbium sensitized fluorescence method as an alternative approach to the Folin–Ciocalteu spectrophotometric method  

Microsoft Academic Search

A fast screening of total phenols in tea infusions, tomato and apple juice samples using terbium sensitized fluorescence is described. The proposed method is based on the fluorescence sensitization of terbium (Tb3+) by complexation with flavonols (quercein as a reference standard) (at pH 7.0), which fluoresces intensely with an emission maximum at 545nm when excited at 310nm. Quercetin and terbium

Masoomeh Shaghaghi; Jamshid L. Manzoori; Abolghasem Jouyban

2008-01-01

359

A Microscale Spectrophotometric Determination of Water Hardness  

NASA Astrophysics Data System (ADS)

A spectrophotometric titration was performed to determine water hardness. The titration incorporated the traditional titration method employing EDTA as the titrant and calmagite as the indicator. The microscale experiment was carried out in a spectrometer cuvette and made use of a Texas Instruments (TI-83) calculator interfaced through a TI Calculator-Based Laboratory system to a Vernier colorimeter as the detector. Monitoring at 635 nm, one of the colorimeter's fixed wavelengths, was well suited for this analysis. Agreement was found with results from traditional titrations.

Gordon, James S.

2001-08-01

360

Stability indicating HPLC-UV method for detection of curcumin in Curcuma longa extract and emulsion formulation.  

PubMed

A stability-indicating HPLC-UV method for the determination of curcumin in Curcuma longa extract and emulsion was developed. The system suitability parameters, theoretical plates (N), tailing factor (T), capacity factor (K'), height equivalent of a theoretical plate (H) and resolution (Rs) were calculated. Stress degradation studies (acid, base, oxidation, heat and UV light) of curcumin were performed in emulsion. It was found that N>6500, T<1.1, K' was 2.68-3.75, HETP about 37 and Rs was 1.8. The method was linear from 2 to 200 ?g/mL with a correlation coefficient of 0.9998. The intra-day precision and accuracy for curcumin were ?0.87% and ?2.0%, while the inter-day precision and accuracy values were ?2.1% and ?-1.92. Curcumin degraded in emulsion under acid, alkali and UV light. In conclusion, the stability-indicating method could be employed to determine curcumin in bulk and emulsions. PMID:25306352

Syed, Haroon Khalid; Liew, Kai Bin; Loh, Gabriel Onn Kit; Peh, Kok Khiang

2015-03-01

361

Combined cloud point-solid phase extraction by dispersion of TiO? nanoparticles in micellar media followed by semi-microvolume UV-vis spectrophotometric detection of zinc.  

PubMed

A new approach is presented in this paper by using dispersed TiO2 nanoparticles (TiO2-NPs) in a combined cloud point and solid phase extraction for the efficient preconcentration and determination of Zn(2+) in various samples. In this method Zn(2+) ions are adsorbed on TiO2-NPs and transferred into surfactant rich phase. Subsequently the Zn(2+) ions are desorbed from TiO2-NPs by a dithizone solution via forming a color complex which could be detected colorimetrically. The influence of chemical variables such as pH of the sample solution, electrolyte, amount of TiO2-NPs, type and volume of the eluent on the extraction system was studied. The calibration graph was linear in the range of 0.5-90.0 µg L(-1) of Zn(2+) (r=0.9996). An enrichment factor of 80 was achieved and the limit of detection for Zn(2+) was 0.33 µg L(-1). The relative standard deviation (RSD) for eight replicate measurements of 10 µg L(-1) and 60 µg L(-1) of Zn(2+) was 1.8% and 1.5% respectively. The proposed method was successfully applied to the quantitative determination of Zn(2+) in tap water, powder milk and Zinc sulfate tablet with satisfactory results. PMID:25059144

Pourreza, Nahid; Naghdi, Tina

2014-10-01

362

APPARATUS AND METHOD FOR TREATING POLLUTANTS IN A GAS USING HYDROGEN PEROXIDE AND UV LIGHT  

NASA Technical Reports Server (NTRS)

An apparatus for treating pollutants in a gas may include a source of hydrogen peroxide, and a treatment injector for creating and injecting dissociated hydrogen peroxide into the flow of gas. The treatment injector may further include an injector housing having an inlet, an outlet, and a hollow interior extending there between. The inlet may be connected in fluid communication with the source of hydrogen peroxide so that hydrogen peroxide flows through the hollow interior and toward the outlet. At least one ultraviolet (UV) lamp may be positioned within the hollow interior of the injector housing. The at least one UV lamp may dissociate the hydrogen peroxide flowing through the tube. The dissociated hydrogen peroxide may be injected into the flow of gas from the outlet for treating pollutants, such as nitrogen oxides.

Cooper, Charles David (Inventor); Clauseu, christian Anthony (Inventor)

2005-01-01

363

Apparatus and method for treating pollutants in a gas using hydrogen peroxide and UV light  

NASA Technical Reports Server (NTRS)

An apparatus for treating pollutants in a gas may include a source of hydrogen peroxide, and a treatment injector for creating and injecting dissociated hydrogen peroxide into the flow of gas. The treatment injector may further include an injector housing having an inlet, an outlet, and a hollow interior extending therebetween. The inlet may be connected in fluid communication with the source of hydrogen peroxide so that hydrogen peroxide flows through the hollow interior and toward the outlet. At least one ultraviolet (UV) lamp may be positioned within the hollow interior of the injector housing. The at least one UV lamp may dissociate the hydrogen peroxide flowing through the tube. The dissociated hydrogen peroxide may be injected into the flow of gas from the outlet for treating pollutants, such as nitrogen oxides.

Cooper, Charles David (Inventor); Clausen, Christian Anthony (Inventor)

2005-01-01

364

Green synthesis of silver/montmorillonite/chitosan bionanocomposites using the UV irradiation method and evaluation of antibacterial activity.  

PubMed

In this study, silver nanoparticles (Ag-NPs) were synthesized using a green physical synthetic route into the lamellar space of montmorillonite (MMT)/chitosan (Cts) utilizing the ultraviolet (UV) irradiation reduction method in the absence of any reducing agent or heat treatment. Cts, MMT, and AgNO(3) were used as the natural polymeric stabilizer, solid support, and silver precursor, respectively. The properties of Ag/MMT/Cts bionanocomposites (BNCs) were studied as the function of UV irradiation times. UV irradiation disintegrated the Ag-NPs into smaller sizes until a relatively stable size and size distribution were achieved. Meanwhile, the crystalline structure and d-spacing of the MMT interlayer, average size and size distribution, surface morphology, elemental signal peaks, functional groups, and surface plasmon resonance of Ag/MMT/Cts BNCs were determined by powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray fluorescence, Fourier transform infrared, and UV-visible spectroscopy. The antibacterial activity of Ag-NPs in MMT/Cts was investigated against Gram-positive bacteria, ie, Staphylococcus aureus and methicillin-resistant S. aureus and Gram-negative bacteria (ie, Escherichia coli) by the disk diffusion method on Muller-Hinton Agar at different sizes of Ag-NPs. All of the synthesized Ag/MMT/Cts BNCs were found to have high antibacterial activity. These results show that Ag/MMT/Cts BNCs can be useful in different biologic research and biomedical applications, such as surgical devices and drug delivery vehicles. PMID:21116328

Shameli, Kamyar; Ahmad, Mansor Bin; Yunus, Wan Md Zin Wan; Rustaiyan, Abdolhossein; Ibrahim, Nor Azowa; Zargar, Mohsen; Abdollahi, Yadollah

2010-01-01

365

Green synthesis of silver/montmorillonite/chitosan bionanocomposites using the UV irradiation method and evaluation of antibacterial activity  

PubMed Central

In this study, silver nanoparticles (Ag-NPs) were synthesized using a green physical synthetic route into the lamellar space of montmorillonite (MMT)/chitosan (Cts) utilizing the ultraviolet (UV) irradiation reduction method in the absence of any reducing agent or heat treatment. Cts, MMT, and AgNO3 were used as the natural polymeric stabilizer, solid support, and silver precursor, respectively. The properties of Ag/MMT/Cts bionanocomposites (BNCs) were studied as the function of UV irradiation times. UV irradiation disintegrated the Ag-NPs into smaller sizes until a relatively stable size and size distribution were achieved. Meanwhile, the crystalline structure and d-spacing of the MMT interlayer, average size and size distribution, surface morphology, elemental signal peaks, functional groups, and surface plasmon resonance of Ag/MMT/Cts BNCs were determined by powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray fluorescence, Fourier transform infrared, and UV-visible spectroscopy. The antibacterial activity of Ag-NPs in MMT/Cts was investigated against Gram-positive bacteria, ie, Staphylococcus aureus and methicillin-resistant S. aureus and Gram-negative bacteria (ie, Escherichia coli) by the disk diffusion method on Muller–Hinton Agar at different sizes of Ag-NPs. All of the synthesized Ag/MMT/Cts BNCs were found to have high antibacterial activity. These results show that Ag/MMT/Cts BNCs can be useful in different biologic research and biomedical applications, such as surgical devices and drug delivery vehicles. PMID:21116328

Shameli, Kamyar; Ahmad, Mansor Bin; Yunus, Wan Md Zin Wan; Rustaiyan, Abdolhossein; Ibrahim, Nor Azowa; Zargar, Mohsen; Abdollahi, Yadollah

2010-01-01

366

Novel spectrophotometric determination of flumethasone pivalate and clioquinol in their binary mixture and pharmaceutical formulation  

NASA Astrophysics Data System (ADS)

This work is concerned with development and validation of three simple, specific, accurate and precise spectrophotometric methods for determination of flumethasone pivalate (FP) and clioquinol (CL) in their binary mixture and ear drops. Method A is a ratio subtraction spectrophotometric one (RSM). Method B is a ratio difference spectrophotometric one (RDSM), while method C is a mean center spectrophotometric one (MCR). The calibration curves are linear over the concentration range of 3-45 ?g/mL for FP, and 2-25 ?g/mL for CL. The specificity of the developed methods was assessed by analyzing different laboratory prepared mixtures of the FP and CL. The three methods were validated as per ICH guidelines; accuracy, precision and repeatability are found to be within the acceptable limits.

Abdel-Aleem, Eglal A.; Hegazy, Maha A.; Sayed, Nour W.; Abdelkawy, M.; Abdelfatah, Rehab M.

2015-02-01

367

UV-vis spectra as an alternative to the Lowry method for quantify hair damage induced by surfactants.  

PubMed

It is well known that long term use of shampoo causes damage to human hair. Although the Lowry method has been widely used to quantify hair damage, it is unsuitable to determine this in the presence of some surfactants and there is no other method proposed in literature. In this work, a different method is used to investigate and compare the hair damage induced by four types of surfactants (including three commercial-grade surfactants) and water. Hair samples were immersed in aqueous solution of surfactants under conditions that resemble a shower (38 °C, constant shaking). These solutions become colored with time of contact with hair and its UV-vis spectra were recorded. For comparison, the amount of extracted proteins from hair by sodium dodecyl sulfate (SDS) and by water were estimated by the Lowry method. Additionally, non-pigmented vs. pigmented hair and also sepia melanin were used to understand the washing solution color and their spectra. The results presented herein show that hair degradation is mostly caused by the extraction of proteins, cuticle fragments and melanin granules from hair fiber. It was found that the intensity of solution color varies with the charge density of the surfactants. Furthermore, the intensity of solution color can be correlated to the amount of proteins quantified by the Lowry method as well as to the degree of hair damage. UV-vis spectrum of hair washing solutions is a simple and straightforward method to quantify and compare hair damages induced by different commercial surfactants. PMID:25277290

Pires-Oliveira, Rafael; Joekes, Inés

2014-11-01

368

Estimation of scattering error in spectrophotometric measurements of light absorption  

E-print Network

Estimation of scattering error in spectrophotometric measurements of light absorption by aquatic scattering error in measurements of light absorption by aquatic particles with a typical laboratory double function of particles. We applied this method to absorption mea- surements made on marine phytoplankton

Stramski, Dariusz

369

Development of a selective and sensitive spectrophotometric method for the trace determination of thallium(III) using 3-methyl-2-benzothiazolinone hydrazone hydrochloride and N-(1-naphthyl)-ethylenediamine dihydrochloride.  

PubMed

A simple, selective, sensitive, and rapid spectrophotometric method has been developed for the determination of thallium(III) using 3-methyl-2-benzothiazolinone hydrazone hydrochloride and N-(1-naphthyl)-ethylenediamine dihydrochloride. The obtained product had an absorption maximum of 590 nm. Beer's law was valid over the concentration range of 0.15-8 microg/mL. The molar absorptivity and Sandell's sensitivity of the colored system were 2.93 x 10(4) L/mol x cm and 0.00723 microg/mL, respectively. The effect of different acids on the sensitivity of the method, interference by foreign substances, the optimum reaction conditions, and other analytical parameters were evaluated. The proposed method has been successfully applied in the analysis of T1(III) in standard reference materials, synthetic mixtures, and water and urine samples. The performance of the proposed method was evaluated in terms of Student's t-test and variance ratio F-test, which indicated the significance of the proposed method over reported methods. PMID:18980127

Nagaraja, Padmarajaiah; Al-Tayar, Naef Ghllab Saeed; Kumar, Anantharaman Shiva

2008-01-01

370

[Research on structure and UV curing behaviors of novel cardanol-based unsaturated resins using FTIR spectrum analysis method].  

PubMed

Two dissimilar cardanol-based unsaturated resin monomers were prepared via simple ring-opening and etherification reaction by utilizing the reactivity between phenolic hydroxyl and epoxy group with the aid of cardanol as raw material. The transformations of different groups were characterized using Fourier transform infrared (FTIR) during the synthesis process, the resin monomers' structure was further analyzed using the 1H-nuclear magnetic resonance (1H-NMR) and gel permeation chromatography (GPC), and the UV curing behaviors of resin monomers were studied by means of FTIR method. In addition, the thermal stability of UV cured resin monomers were also tested by thermogravimetric analysis (TGA). The molecular structure analysis demonstrated that these two target products were successfully synthesized. UV curing behaviors analysis showed that the prepared cardanol-based unsaturated resin monomers could reach ultimate curing level within 30 s. TGA results showed that the molecular structure and the content of double bond had critical influence on their thermal stability. The main initial thermal decomposition temperature of these two cured resin monomers was all above 350 degrees C. PMID:24409711

Li, Shou-Hai; Yang, Xue-Juan; Li, Mei; Huang, Kun; Xia, Jian-Ling

2013-10-01

371

Spectrophotometric and spectrodensitometric determination of triamterene and xipamide in pure form and in pharmaceutical formulation.  

PubMed

Sensitive and validated UV-spectrophotometric, chemometric and TLC-densitometric methods were developed for determination of triamterene (TRM) and xipamide (XIP) in their binary mixture, formulated for use as a diuretic, without previous separation. Method A is the isoabsorptive point spectrophotometry, in which TRM concentration alone can be determined at its ?(max) while XIP concentration can be determined by measuring total concentration of TRM and XIP at their isoabsorptive point followed by subtraction. Method B is the ratio subtraction spectrophotometry, where XIP can be determined by dividing the spectrum of the mixture by the spectrum of TRM (as a divisor) followed by subtracting the constant absorbance value of the plateau region, then finally multiplying the produced spectrum by the spectrum of the divisor, while TRM concentration can be determined at its ?(max). Method C is a chemometric-assisted spectrophotometry where classical least squares, principal component regression, and partial least squares were applied. Method D is a TLC-densitometry; this method depends on quantitative densitometric separation of thin layer chromatogram of TRM and XIP using silica gel plates at 254 nm. The proposed methods were successfully applied for the analysis of TRM and XIP in their pharmaceutical formulation and the results were statistically compared with the established HPLC method. PMID:20878892

Wagieh, Nour E; Abbas, Samah S; Abdelkawy, M; Abdelrahman, Maha M

2010-03-01

372

Adverse Effects of UV-B Radiation on Plants Growing at Schirmacher Oasis, East Antarctica.  

PubMed

This study aimed to assess the impacts of ultraviolet-B (UV-B) radiation over a 28-day period on the levels of pigments of Umbilicaria aprina and Bryum argenteum growing in field. The depletion of stratospheric ozone is most prominent over Antarctica, which receives more UV-B radiation than most other parts of the planet. Although UV-B radiation adversely affects all flora, Antarctic plants are better equipped to survive the damaging effects of UV-B owing to defenses provided by UV-B absorbing compounds and other screening pigments. The UV-B radiations and daily average ozone values were measured by sun photometer and the photosynthetic pigments were analyzed by the standard spectrophotometric methods of exposed and unexposed selected plants. The daily average atmospheric ozone values were recorded from 5 January to 2 February 2008. The maximum daily average for ozone (310.7 Dobson Units (DU)) was recorded on 10 January 2008. On that day, average UV-B spectral irradiances were 0.016, 0.071, and 0.186 W m(-2) at wavelengths of 305, 312, and 320 nm, respectively. The minimum daily average ozone value (278.6 DU) was recorded on 31 January 2008. On that day, average UV-B spectral irradiances were 0.018, 0.085, and 0.210 W m(-2) at wavelengths of 305, 312, and 320 nm, respectively. Our results concludes that following prolonged UV-B exposure, total chlorophyll levels decreased gradually in both species, whereas levels of UV-B absorbing compounds, phenolics, and carotenoids gradually increased. PMID:24748743

Singh, Jaswant; Singh, Rudra P

2014-01-01

373

Adverse Effects of UV-B Radiation on Plants Growing at Schirmacher Oasis, East Antarctica  

PubMed Central

This study aimed to assess the impacts of ultraviolet-B (UV-B) radiation over a 28-day period on the levels of pigments of Umbilicaria aprina and Bryum argenteum growing in field. The depletion of stratospheric ozone is most prominent over Antarctica, which receives more UV-B radiation than most other parts of the planet. Although UV-B radiation adversely affects all flora, Antarctic plants are better equipped to survive the damaging effects of UV-B owing to defenses provided by UV-B absorbing compounds and other screening pigments. The UV-B radiations and daily average ozone values were measured by sun photometer and the photosynthetic pigments were analyzed by the standard spectrophotometric methods of exposed and unexposed selected plants. The daily average atmospheric ozone values were recorded from 5 January to 2 February 2008. The maximum daily average for ozone (310.7 Dobson Units (DU)) was recorded on 10 January 2008. On that day, average UV-B spectral irradiances were 0.016, 0.071, and 0.186 W m-2 at wavelengths of 305, 312, and 320 nm, respectively. The minimum daily average ozone value (278.6 DU) was recorded on 31 January 2008. On that day, average UV-B spectral irradiances were 0.018, 0.085, and 0.210 W m-2 at wavelengths of 305, 312, and 320 nm, respectively. Our results concludes that following prolonged UV-B exposure, total chlorophyll levels decreased gradually in both species, whereas levels of UV-B absorbing compounds, phenolics, and carotenoids gradually increased. PMID:24748743

Singh, Jaswant; Singh, Rudra P.

2014-01-01

374

A Spectrophotometric Study of the Permanganate-Oxalate Reaction: An Analytical Laboratory Experiment  

ERIC Educational Resources Information Center

The spectrophotometric method assists in the study of potassium permanganate-oxalate reaction. Basic analytical techniques and rules are implemented in the experiment, which can also include the examination of other compounds oxidized by permanganate.

Kalbus, Gene E.; Lieu, Van T.; Kalbus, Lee H.

2004-01-01

375

Analytical method for the determination of cyromazine and melamine residues in soil using LC-UV and GC-MSD.  

PubMed

A method is reported for the determination of cyromazine and melamine residues in soil. Soil samples are extracted twice via mechanical shaking, each time with 70% acetonitrile/30% 0.050 M ammomium carbonate for 30 min. An aliquot portion of the pooled extracts is subjected to strong cation exchange (SCX) purification on AG 50W-X4 resin. Final analysis is accomplished using liquid chromatography-ultraviolet (LC-UV) detection at a wavelength of 214 nm. Confirmatory analyses can be performed using gas chromatography-mass selective detection (GC-MSD) in the selected ion monitoring (SIM) mode. The limit of detection (LOD) is 2.5 ng injected and the limit of quantification (LOQ) is 10 ppb when using LC-UV for the analysis of N-cyclopropyl-1,3,5-triazine-2,4, 6-triamine (cyromazine) and 1,3,5-triazine-2,4,6-triamine (melamine). The LOD is 0.050 ng injected and the LOQ is 10 ppb when using GC-MSD for confirmatory analyses. The mean procedural recoveries were 97 and 95% and the standard deviations were 16 and 11% for cyromazine and melamine, respectively (n = 24), when using LC-UV. The mean procedural recoveries were 107 and 92% and the standard deviations were 9.9 and 16% for cyromazine and melamine, respectively (n = 29), when using GC-MSD. The method validation study was conducted under U.S. EPA FIFRA Good Laboratory Practice Guidelines 40 CFR 160. The method also passed an Independent Laboratory Validation (ILV) as per U.S. EPA FIFRA Subdivision N. PMID:10956115

Yokley, R A; Mayer, L C; Rezaaiyan, R; Manuli, M E; Cheung, M W

2000-08-01

376

Characteristics of photoconductive UV photodetector based on ZnO nanorods grown on polyethylene naphthalate substrate by chemical bath deposition method  

NASA Astrophysics Data System (ADS)

Vertically aligned ZnO nanorods were synthesized on a polyethylene naphthalate (PEN) substrate using a chemical bath deposition method at a low temperature. The structural and optical investigations revealed the high quality of the fabricated ZnO nanorods on flexible substrate. A metal-semiconductor-metal UV photodetector based on ZnO nanorods was fabricated on the PEN substrate. The optoelectronic characteristics of fabricated UV photodetector were studied in the dark and under 325 nm UV light illumination at -3 V and 3 V bias voltages. The responsivity and photosensitivity of the ZnO nanorod UV photodetector were 2.856 A/W and 1175% at 3 V bias voltage, respectively. Moreover, the response and the recovery times measured during the turn-on and turnoff of UV illumination were 1.2 s and 1.8 s, respectively.

Shabannia, R.; Hassan, H. Abu

2014-07-01

377

Effects of UV assistance on the properties of al-doped ZnO thin films deposited by sol-gel method  

NASA Astrophysics Data System (ADS)

We report here the preparation of aluminum doped zinc oxide transparent conductive thin films by a UV-assisted sol-gel method. It was found that UV irradiation creates ozone, which promotes the conductivity and transparency of the films. Boro-silicate glasses are used as substrates; an PGME is used as a solvent; after spin-coating, the films are dried and radiated with UV and then heated to 400°C for decarburization and 500°C for annealing under air. The surface morphologies of the prepared films are observed by FE-SEM and AFM. It was found that the films irradiated with UV-C are smoother and denser. An XRD analysis shows that the films have a typical wurtzite crystalline structure with a c-axis orientation normal to the surface. The electric resistance values measured with a four-point probe show that the films irradiated with UV have better conductivity (at approximately 3.4 × 10-3?-cm) than the films that did not undergo UV irradiation. An analysis by visible light spectrometry indicates that the AZO films irradiated with UV are more transparent than the films without UV-irradiation.

Tseng, Yung-Kuan; Pai, Feng-Ming; Chen, Yan-Cheng; Wu, Chao-Hsien

2013-11-01

378

Spectrophotometric assay for ornithine decarboxylase.  

PubMed

A rapid and sensitive spectrophotometric assay for ornithine decarboxylase is described. It is based on the observation that the product of ornithine decarboxylase, putrescine, reacts with 2,4,6-trinitrobenzenesulfonic acid to give a colored product soluble in 1-pentanol whereas ornithine does not. The amount of putrescine produced by the enzyme was determined by measuring the absorbance of the 1-pentanol extract of the reaction mixture at 420 nm, and by comparing the results to those obtained by the trapping of 14CO2 and by HPLC assays. The three assays were found to be equivalent in sensitivity, with the spectrophotometric assay having the advantages of being relatively rapid, requiring only common laboratory equipment, and not requiring the use of radioactive isotopes. PMID:3578755

Ngo, T T; Brillhart, K L; Davis, R H; Wong, R C; Bovaird, J H; Digangi, J J; Ristow, J L; Marsh, J L; Phan, A P; Lenhoff, H M

1987-02-01

379

Defects in UV-vis-NIR reflectance spectra as method for forgery detections in writing documents  

NASA Astrophysics Data System (ADS)

Documents have taken up a very important place in our society. Frauds committed in connection with documents are not at all uncommon, and, in fact, represent a very large domain of the forensic science called "questioned documents". In the field of forensic examination of questioned documents, the legitimacy of an ink entry is often an essential question. A common type of forgery consists in materially altering an existing writing or adding a new writing. These changes can be characterized by means of optical spectroscopy. The aim of this work is to perform the UV-vis-NIR reflectance spectrophotometry to analyze a range of blue and black commercial ballpoint pens, in order to investigate the discriminating abilities of the different inks found on the same document.

Somma, F.; Aloe, P.; Schirripa Spagnolo, G.

2010-11-01

380

Determination of Nonionic Surfactant in Liquid Detergent by UV-vis Spectrophotometry and Multivariate Calibration Method  

NASA Astrophysics Data System (ADS)

The aim of this study was determination of lauramide as a nonionic surfactant in liquid detergent using multivariate calibration. A Partial Least Squares (PLS) algorithm is used to perform the calibration. The concentration of lauramide for experimental calibration matrix was varied between 0.005-0.020 g mL-1. Absorbance data of the calibration standards were taken between 200-600 nm with UV-vis spectrometer. Then absorbance data and concentration were fed to model as input and output, respectively. For achieving the best model parameters of model were evaluated. In other step, first order derivative spectra were considered as input of model and parameters of model were tested. The relative errors in each step were calculated. Relative error less than 2.7% for zero and first derivative spectral data set respectively, were obtained.

Sohrabi, Mahmoud Reza; Hassan Nouri, Arezoo; Adnani, Atena; Fard Masoumi, Hamidreza

381

Spectrophotometric and atomic absorption spectrometric determination of ramipril and perindopril through ternary complex formation with eosin and Cu(II)  

Microsoft Academic Search

Two sensitive, spectrophotometric and atomic absorption spectrometric procedures are developed for the determination of ramipril and perindopril. Both methods are based on the formation of a ternary complex, extractable with chloroform, between copper(II), eosin and the two cited drugs. Spectrophotometrically under the optimum condition, the ternary complexes showed an absorption maximum at 535 nm, with apparent molar absorptivities of 6.55

Hisham E. Abdellatef; Magda M. Ayad; Elham A. Taha

1999-01-01

382

[Usefulness of one point measurement method of pediatric dose and UV spectrophotometry for filterability test of in-line filter].  

PubMed

The adsorption of Bevacizumab, Trastuzumab, Rituximab, Nedaplatin, Vincristine sulfate, Nogitecan hydrochloride, Actinomycin D and Ramosetron hydrochloride to 0.2 ?m endotoxin-retentive in-line filters was evaluated with pediatric doses by UV spectrophotometry. The results indicated that some drug adsorption was shown with Nogitecan hydrochloride, Actinomycin D and Ramosetron hydrochloride, and good recovery was shown with the other five drugs. For the three drugs which showed some losses, drug recovery was investigated at multiple test doses. The approximation formula for each drug adsorption was recorded as Y=100-A/X (X: dose (mg), Y: recovery rate (%), A: a constant for individual drug). The results showed there was high correlation between the reciprocal of test drug dose and the recovery rate. Furthermore, in the cases where adsorption to the filter were observed, it was found that it was possible to determine the relationship between dose and the recovery rate from a filterability test with one point pediatric dose. Since the recovery rate obtained from the approximation formula with multiple doses and that calculated from the prediction formula with one point pediatric dose were almost the same, then it was concluded that it is not necessary to conduct the filterability tests with multiple doses. We have shown that using UV spectrophotometry and carrying out a filterability test using one point pediatric dose is relatively easy method and reduces the effort and expense. This method for analysis of drug adsorption is extremely useful when using in-line filters with infusion therapy. PMID:24790051

Yamanouchi, Tsuneaki; Horiuchi, Kenichi; Ishii, Kazunari; Mimura, Yasuhiko; Kato, Atsushi; Adachi, Isao

2014-01-01

383

Spectrophotometric determination of vanadium in crude oil  

NASA Astrophysics Data System (ADS)

Spectrophotometric method has been developed for the determination of vanadium after derivatization with 2-pyrrolealdehyde phenylsemicarbazone (PPS). The linear calibration curve was obtained with 2.5 20?g/ml vanadium. Copper(II), cobalt(II), iron(II) and palladium(II) could also be determined separately using PPS with linear calibration curves within 2.5 12.5, 5 15, 2.5 15 and 1 5?g/ml at 362, 355, 355 and 365 nm, respectively. The vanadium in crude oil was determined with relative deviation (RSD) of 2.5 5.0%. The methods have been applied for the analysis of copper from copper wires, cobalt from pharmaceutical preparation and palladium from palladium on barium sulphate with RSD within 2.6 4.5%.

Mastoi, G. M.; Khuhawar, M. Y.; Bozdar, R. B.

2006-11-01

384

Comparison of multivariate calibration methods to determine simultaneously mebendazole-cambendazole and mebendazole-thiabendazole in pharmaceutical preparations by UV-visible spectrophotometry.  

PubMed

Three multivariate calibration methods, Principal Component Regression (PCR), the K-matrix method and Q-mode factor analysis followed by varimax and Imbrie's oblique rotations were applied to the simultaneous spectrophotometric determinations of mebendazole (MBZ)-cambendazole (CBZ) and thiabendazole (TBZ)-mebendazole in commercial samples of Exelmin and Helmiben. The calibration set concentrations were selected to contain a +/-10% variation in the quantity of active ingredients as declared by the manufacturer. The Q-mode factor analysis provides superior results for the two pharmaceutical formulations. The K-matrix method proved to be totally inadequate for these determinations. Almost all Q-mode results have relative errors much smaller than 5% of the active ingredient contents. This investigation shows that PCR and Q-mode factor analysis can be used to determine MBZ-CBZ and TBZ-MBZ in commercial drugs. PMID:14623591

Andrade, Suely R C; Scarminio, Ieda S; Nery, Marlene M F; de Oliveira, Aline C

2003-11-24

385

New developments for the numerical analysis of spectrophotometric titrations  

Microsoft Academic Search

Spectrophotometric titrations are a valuable tool for the investigation of solution equilibria. Data acquisition and recent developments on methods for the analysis of the measurements are discussed in this contribution. Hard-modeling methods are based on non-linear least-squares fitting, and algorithms have been developed which can cope with the large amount of data and parameters of multiwavelength or multivariate measurements. Good

Raylene M. Dyson; Porn Jandanklang; Marcel Maeder; Caroline J. Mason; Andrew Whitson

1999-01-01

386

Spectrophotometric determination of metronidazole and tinidazole in pharmaceutical preparations  

Microsoft Academic Search

Sensitive and simple spectrophotometric methods for the determination of metronidazole (MNZ) and tinidazole (TNZ) in either pure form or in its pharmaceutical formulations are described. The first method is based on the interaction of 3-methylbenzothiazolin-2-one hydrazone (MBTH) with MNZ\\/TNZ (reduced drug) in presence of copper sulphate and pyridine in acidic medium. The resulting yellowish orange products have ?max of 500

P. Nagaraja; K. R. Sunitha; R. A. Vasantha; H. S. Yathirajan

2002-01-01

387

Near UV-near IR Fourier transform spectrometer using the beam-folding position-tracking method based on retroreflectors  

NASA Astrophysics Data System (ADS)

A near UV-near IR Fourier transform spectrometer based on a beam-folding position-tracking method realized by using retroreflectors is reported. The use of retroreflectors maintains all beams in the beam-fold arrangement in parallel with the incident beams. The beam-folding interferometer used for position tracking is arranged to have optical path symmetry with the measurement interferometer in the zero path difference position of the measurement interferometer, and the vertex of the movable retroreflector in the measurement interferometer is arranged very close to the midpoint of the vertices of two movable retroreflectors in the position-tracking interferometer. These measures keep the equivalent optical axis of the position-tracking interferometer well in line with that of the measurement interferometer even with translational misalignments. Therefore, the change in the optical path difference of the position-tracking interferometer is always synchronous to that of the measurement interferometer during the scanning process. That is, the position-tracking error can be suppressed to very small values during a scan. We have demonstrated a UV-near IR Fourier transform spectrometer with a standard quality ball-bearing translation stage achieving a resolution close to the theoretical resolution of ˜0.28 cm-1 at the He-Ne laser wavelength when the scan distance reaches the travel distance of over 2 cm. This was achieved without the need for elaborate optics, sophisticated detecting electronics, and high-precision servomotion control.

Wang, Xuzhu; Chan, Robert K. Y.; Cheng, Amelia S. K.

2008-12-01

388

Development of a non-thermal accelerated pulsed UV photolysis assisted digestion method for fresh and dried food samples  

NASA Astrophysics Data System (ADS)

A simple, fast digestion procedure for fresh and dried foods, using high-power pulsed UV photolysis in the presence of hydrogen peroxide, is being developed. The homogenized food samples were mixed with H 2O 2 or with a mixture of H 2O 2 and HNO 3, and irradiated for short times with a 248-nm UV excimer laser. After centrifugation, a clear, colorless solution was obtained and aliquots were deposited on Teflon filters for XRF and/or PIXE analyses. Standard reference materials (NIST Peach Leaves; Typical Diet) were also analyzed to compare recoveries and detection limits. Improvements in detection limits were observed, but a few trace elements (<1 ppm) were not reproducibly detected (Fe, Sr). This method proved to be practical for the accelerated digestion of food samples and preparing analytes in short-time intervals. In combination with PIXE and XRF, it allows high-sensitivity multi-elemental analyses for screening the nutritional elements and for food safety purposes regarding the potential presence of toxic elements. Further development to optimize and validate this procedure for a broader range of analytes is in progress.

Solís, C.; Lagunas-Solar, M. C.; Perley, B. P.; Piña, C.; Aguilar, L. F.; Flocchini, R. G.

2002-04-01

389

Near UV-near IR Fourier transform spectrometer using the beam-folding position-tracking method based on retroreflectors.  

PubMed

A near UV-near IR Fourier transform spectrometer based on a beam-folding position-tracking method realized by using retroreflectors is reported. The use of retroreflectors maintains all beams in the beam-fold arrangement in parallel with the incident beams. The beam-folding interferometer used for position tracking is arranged to have optical path symmetry with the measurement interferometer in the zero path difference position of the measurement interferometer, and the vertex of the movable retroreflector in the measurement interferometer is arranged very close to the midpoint of the vertices of two movable retroreflectors in the position-tracking interferometer. These measures keep the equivalent optical axis of the position-tracking interferometer well in line with that of the measurement interferometer even with translational misalignments. Therefore, the change in the optical path difference of the position-tracking interferometer is always synchronous to that of the measurement interferometer during the scanning process. That is, the position-tracking error can be suppressed to very small values during a scan. We have demonstrated a UV-near IR Fourier transform spectrometer with a standard quality ball-bearing translation stage achieving a resolution close to the theoretical resolution of approximately 0.28 cm(-1) at the He-Ne laser wavelength when the scan distance reaches the travel distance of over 2 cm. This was achieved without the need for elaborate optics, sophisticated detecting electronics, and high-precision servomotion control. PMID:19123546

Wang, Xuzhu; Chan, Robert K Y; Cheng, Amelia S K

2008-12-01

390

Hybrid hard- and soft-modeling of spectrophotometric data for monitoring of ciprofloxacin and its main photodegradation products at different pH values  

NASA Astrophysics Data System (ADS)

A simple and fast on line spectrophotometric method combined with a hybrid hard-soft modeling multivariate curve resolution (HS-MCR) was proposed for the monitoring of photodegradation reaction of ciprofloxacin under UV radiation. The studied conditions attempt to emulate the effect of sunlight on these antibiotics that could be eventually present in the environment. The continuous flow system made it possible to study the ciprofloxacin degradation at different pH values almost at real time, avoiding errors that could arise from typical batch monitoring of the reaction. On the base of a concentration profiles obtained by previous pure soft-modeling approach, reaction pathways have been proposed for the parent compound and its photoproducts at different pH values. These kinetic models were used as a constraint in the HS-MCR analysis. The kinetic profiles and the corresponding pure response profile (UV-Vis spectra) of ciprofloxacin and its main degradation products were recovered after the application of HS-MCR analysis to the spectra recorded throughout the reaction. The observed behavior showed a good agreement with the photodegradation studies reported in the bibliography. Accordingly, the photodegradation reaction was studied by high performance liquid chromatography coupled with UV-Vis diode array detector (HPLC-DAD). The spectra recorded during the chromatographic analysis present a good correlation with the ones recovered by UV-Vis/HS-MCR method.

Razuc, Mariela; Garrido, Mariano; Caro, Yamile S.; Teglia, Carla M.; Goicoechea, Héctor C.; Fernández Band, Beatriz S.

2013-04-01

391

A method of atmospheric density measurements during Shuttle entry using UV laser Rayleigh scattering  

Microsoft Academic Search

A detailed study is described of the performance capabilities and the hardware requirements for a method in which ambient density is measured along the Space Shuttle flight path using on-board optical instrumentation. The technique relies on Rayleigh scattering of light from a pulsed, ultraviolet, ArF excimer laser operating at a wavelength of 193 nm. The method is shown to be

Robert L. McKenzie

1987-01-01

392

A sensitive spectrophotometric assay for guanase activity.  

PubMed

A highly sensitive and accurate spectrophotometric method was developed for determination of guanase activity with guanine as substrate. The assay is based on the oxidative coupling of 3-methyl-2-benzothiazolinone hydrazone and N,N-diethylaniline. Xanthine formed from guanine by guanase is oxidized to uric acid and hydrogen peroxide by xanthine oxidase, and the hydrogen peroxide produced is determined by an oxidative-coupling reaction with 3-methyl-2-benzothiazolinone hydrazone and N,N-diethylaniline mediated by peroxidase. Formation of the indamine dye is greatly affected by the superoxide radical ion (O2-) and pH value. These problems can be overcome by separating the two reactions of hydrogen peroxide formation and color production and carrying out that color-producing reaction at pH 3.0. This method is very sensitive and accurate because the indamine dye has a very high molar extinction coefficient of 29,800. It can be used with various kinds of automatic analyzers such as a Hitachi, Olympus, or Technicon analyzer. Comparative studies showed that this method is more sensitive and reproducible than other methods. Furthermore, guanase activities determined by this method correlated well with those determined by the improved Ellis-Goldberg method. This method should be useful for measurement of guanase activity in banked blood for preventing transfusion hepatitis and could be valuable as a liver function test. PMID:6869816

Ando, T; Muraoka, T; Okuda, H

1983-04-15

393

Validation of HPLC-UV method for determination of minor glycosides contained in Stevia rebaudiana Bertoni leaves.  

PubMed

Leaves of Stevia rebaudiana contain glycosides with sweetness and biological activity. However besides the major glycosides, there are other glycosides within extracts that may contribute to its activity, and therefore it is important to quantify them. In this work, an isocratic HPLC method was validated for determination of dulcoside A, steviolbioside, rebaudioside C and rebaudioside B. An HPLC method was performed using a C18 column (250?×?4.6?mm, particle size 5?µm) and a UV detector set at 210?nm. The mobile phase consisted of a 32:68 (v/v) mixture of acetonitrile and sodium phosphate buffer (10?mmol/L, pH?2.6), set to a flow rate of 1.0?mL/min. The calculated parameters were: sensitivity, linearity, limit of detection (LOD), limit of quantification (LOQ), accuracy and precision. The calibration curves were linear over the working range 25-150?µg/mL, with coefficient of correlation of ?0.99 and coefficient of determination of ?0.98. The LOD was 5.68-8.81?µg/mL, while the LOQ was 17.21-26.69?µg/mL. The percentage recoveries of fortified samples were 100?±?10% and precision, relative standard deviation, was <10%. The method validation showed accuracy, linearity and precision; therefore this method can be applied for quantitative analysis of minor steviol glycosides in S. rebaudiana leaves. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25296637

Aranda-González, Irma; Moguel-Ordoñez, Yolanda; Betancur-Ancona, David

2015-05-01

394

Quantitative determination of triperpene saponins and alkenated-phenolics from Labisia pumila using LC-UV/ELSD method and confirmation by LC-ESI-TOF  

Technology Transfer Automated Retrieval System (TEKTRAN)

This study describes the first analytical method for the determination of saponins and alkenated-phenolics from the leaves, leaves/stems and roots of Labisia pumila using a HPLC-UV-ELSD method. The separation was achieved using a reversed phase column, PDA and ELS detection, and a water/acetonitrile...

395

Flow Injection Determination of Chloride Ions with Spectrophotometric Detection  

Microsoft Academic Search

A single-line FIA system with a stream-sample splitting device for chloride determination is presented. The analytical method is based on the FeHg(SCN)2\\/Cl system and the absorbance of the red Fe(SCN) species monitored spectrophotometrically at 480 nm. Using a stream-sample splitting device, the recorded signal is composed of two merged peaks. Three calibration curves were obtained, once injecting the standard solution

Mihaela Cheregi; Andrei F. Danet

1997-01-01

396

Simple Sensitive Spectrophotometric Determination of Isoniazid and Ritodrine Hydrochloride  

Microsoft Academic Search

A novel coupling reagent was used for simple, rapid, and sensitive spectrophotometric determination of isoniazid (1NH) and ritodrine hydrochloride (RTH) in pure form or in pharmaceutical preparations of it. The method is based on the diazotization of 4,4-methylene-bis-m-nitroaniline followed by a coupling reaction with either INH or RTH in hydrochloric acid medium. The resulting colored products have absorption maxima at

G. Krishnamurthy Naidu; K. Suvardhan; K. Suresh Kumar; D. Rekha; B. S. Sastry; P. Chiranjeevi

2005-01-01

397

Water-soluble organic nitrogen in atmospheric aerosol: a comparison of UV and persulfate oxidation methods  

Microsoft Academic Search

Two well established methods that are widely applied in the determination of marine dissolved organic nitrogen (DON) have been investigated in their application to the determination of rainwater DON and the water-soluble organic nitrogen component of atmospheric aerosol. Empirical observation highlighted some difficulties in the analysis of DON in these non-marine matrices, so some practical suggestions for the extension of

S. E Cornell; T. D Jickells

1999-01-01

398

A HPLC with UV detection method for the determination of tetracyclines (TCs) residues in chicken liver  

Microsoft Academic Search

A high-performance liquid chromatography with ultraviolet spectrophotometer detection method for the simultaneous determination of oxytetracycline (OTC), tetracycline (TC), chlortetracycline (CTC), and doxycycline (DC) residues in chicken liver was developed and validated. Chicken liver was digested using perchloric acid of 5% mass concentration. The chromatographic separation was performed on an Agilent column. Matrix matched calibration curves showed a linearity exceeding 0.9985.

Zhang Haiying; Chen Donghui; Zheng Yi; Hu Hongtao

2010-01-01

399

New 1,2,4-triazole-based azo-azomethine dye. Part III: Synthesis, characterization, thermal property, spectrophotometric and computational studies  

NASA Astrophysics Data System (ADS)

A new 1,2,4-triazole-based azo-azomethine compound, H2L, has been prepared by condensation reaction of 1-(3-formyl-4-hydroxyphenylazo)-4-ethylbenzene with prepared triazole-based diamine. The structure of H2L was characterized by using FT-IR, UV-Vis and 1H NMR spectroscopic methods as well as elemental analysis. Hard model chemometrics method has been used to determine the formation constants of zinc(II), copper(II), nickel(II) and cobalt(II) complexes of H2L in DMSO by UV-Vis spectrophotometric method. Solvatochromic behavior of the dye has been also investigated in some organic solvents with different polarities. Thermal properties of the prepared dye was examined by thermogravimetric analysis. Results indicated that the framework of the dye was stable up to 245 °C. Furthermore,1H chemical shifts and UV-Vis of H2L were studied by the gauge independent atomic orbital (GIAO), continuous set of gauge transformations (CSGT) and time-dependent density functional theory (TD-DFT) methods respectively at the level of density functional theory using B3LYP/6-311+G(d) basis sets in DMSO. The computational data are in reasonably good agreement with the experimental data.

Erfantalab, Malihe; Khanmohammadi, Hamid

400

New 1,2,4-triazole-based azo-azomethine dye. Part III: Synthesis, characterization, thermal property, spectrophotometric and computational studies.  

PubMed

A new 1,2,4-triazole-based azo-azomethine compound, H2L, has been prepared by condensation reaction of 1-(3-formyl-4-hydroxyphenylazo)-4-ethylbenzene with prepared triazole-based diamine. The structure of H2L was characterized by using FT-IR, UV-Vis and (1)H NMR spectroscopic methods as well as elemental analysis. Hard model chemometrics method has been used to determine the formation constants of zinc(II), copper(II), nickel(II) and cobalt(II) complexes of H2L in DMSO by UV-Vis spectrophotometric method. Solvatochromic behavior of the dye has been also investigated in some organic solvents with different polarities. Thermal properties of the prepared dye was examined by thermogravimetric analysis. Results indicated that the framework of the dye was stable up to 245 °C. Furthermore,(1)H chemical shifts and UV-Vis of H2L were studied by the gauge independent atomic orbital (GIAO), continuous set of gauge transformations (CSGT) and time-dependent density functional theory (TD-DFT) methods respectively at the level of density functional theory using B3LYP/6-311+G(d) basis sets in DMSO. The computational data are in reasonably good agreement with the experimental data. PMID:24577255

Erfantalab, Malihe; Khanmohammadi, Hamid

2014-05-01

401

HPLC-UV method for quantifying etoposide in plasma and tumor interstitial fluid by microdialysis: application to pharmacokinetic studies.  

PubMed

A simple and sensitive bioanalytical method was developed and validated for determination of etoposide in plasma and microdialysis samples of Walker-256 tumor-bearing rats. A microdialysis probe was implanted in the center of a subcutaneous tumor and Ringer's solution was used as perfusion medium. Chromatographic separation was conducted on a Shimadzu CLC-C8 column using a mobile phase consisting of water-acetonitrile (70:30; v/v) adjusted to pH?4.0?±?0.1 with formic acid at a gradient flow rate of 1.0-0.6?mL/min, an injection volume of 30??L and UV detection at 210?nm. Microdialysate samples were analyzed without processing and plasma samples (100??L) were spiked with phenytoin as internal standard (IS) (1?µg/mL) followed by extraction with tert-butyl methyl ether. The organic layer was evaporated and reconstituted with 100??L of mobile phase before injection. The methods for plasma and microdialysate were linear in the ranges of 25-10,000?ng/mL and of 10-1500?ng/mL, respectively. All the validation parameters such as intra- and inter-day precision and accuracy and stability were within the limits established by international guidelines. The present method was successfully applied in the investigation of etoposide pharmacokinetics in rat plasma and microdialysate tumor samples following a single 15?mg/kg intravenous dose. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25137530

Pigatto, Maiara Cássia; Mossmann, Daniele Lenz; Dalla Costa, Teresa

2015-04-01

402

The Simultaneous Determination of Six Flame Retardants in Water Samples Using SPE Pre-concentration and UHPLC-UV Method.  

PubMed

Analytical method for the determination of six flame retardants (FRs) from two groups was proposed. These groups included the brominated flame retardants (BFRs) 3,3',5,5'-tetrabromobisphenol A (TBBPA), 1,2,5,6,9,10-hexabromocyclododecane (HBCD) and tetrabromophthalic anhydride (TBPA) and triester organophosphate flame retardants (OPFRs) tris(2,3-dibromopropyl) phosphate (TBPP), ethylhexyl diphenyl phosphate (EHDP) and triphenyl phosphate (TPhP). Reversed phase ultrahigh-performance liquid chromatography (UHPLC) with a UV detector, different chromatographic columns, different mobile phases and gradient elution programmes were used to obtain the best separations within the shortest possible time. Solid-phase extraction (SPE) was examined as a pre-concentration step from distilled water. The column with the highest recoveries (the Bond Elut ENV column gave recoveries over 70 % for all compounds) was then tested on 1-L blank surface water samples. The proposed analytical procedure was applied for the determination of FRs in surface water samples. The concentrations of FRs found in water samples ranged from 0.03 (TPhP) to 3.10 ?g L(-1) (HBCD). Method detection limits (MDLs) ranged from 0.008 to 0.518 ?g L(-1), and method quantification limits (MQLs) ranged from 0.023 to 1.555 ?g L(-1) for all compounds. PMID:24672141

Kowalski, Bartosz; Mazur, Maciej

2014-01-01

403

Development and validation of an HPLC–UV method for the quantification of carbamazepine in rabbit plasma  

PubMed Central

An isocratic simple rapid assay has been developed and validated for the determination of carbamazepine (CBZ) in both solution form and rabbit plasma using propylparaben as an internal standard. The assay was performed using a ?-Bondapak C18 (150 mm × 4.6 mm i.d) with a mobile phase consisting of methanol and water (50:50), the flow rate was 1 ml/min and UV detection at 285 nm. The method was found to be specific for CBZ, no interfering peaks were observed with an overall analytical run time of 15 min. Accuracy reported as % recovery were found to be 98.37–100.45% and 97.53–103.58% for inter-day and intra-day accuracies, respectively. Inter-day precision (reproducibility) was found to be 0.53–2.75% RSD, while intra-day precision (repeatability) was found to be 1.06–3.7% RSD for the samples studied. The calibration curve was found to be linear with the equation y = 0.2847x + 0.0138, with a correlation coefficient of 0.9999 (R2) over a concentration range of 0.5–40 ?g/ml. The limit of quantitation was the lowest concentration. The method is simple and rapid and does not require any preliminary treatment of the sample. The method was fully validated. PMID:23960774

Mowafy, Hammam A.; Alanazi, Fars K.; El Maghraby, Gamal M.

2011-01-01

404

A method of atmospheric density measurements during Shuttle entry using UV laser Rayleigh scattering  

NASA Technical Reports Server (NTRS)

A detailed study is described of the performance capabilities and the hardware requirements for a method in which ambient density is measured along the Space Shuttle flight path using on-board optical instrumentation. The technique relies on Rayleigh scattering of light from a pulsed, ultraviolet, ArF excimer laser operating at a wavelength of 193 nm. The method is shown to be capable of providing direct measurements of ambient density with an uncertainty of less than 1 percent and with a spatial resolution of 1 km, over an altitude range from 50 to 90 km. In addition, extensions of this concept are discussed that allow measurements of the shock wave location and the density profile within the shock layer. Two approaches are identified that appear to be feasible, in which the same laser system is used for the extended measurements as that required for the ambient density measurements.

Mckenzie, Robert L.

1987-01-01

405

Determination of Ciprofloxacin in Pharmaceutical Formulations Using HPLC Method with UV Detection.  

PubMed

A simple, specific, accurate and rapid reversed phase high performance liquid chromatographic method was validated for the determination of the content of ciprofloxacin in three pharmaceuticals forms: generic, similar and compounded. The results of the validation showed that the method was highly efficient for quantification of ciprofloxacin in the matrices evaluated. The recovery rates were between 97.4 to 104.3 %, and the relative standard deviations were lower than 5 % for repeatability, and lower than 5.15 % for intermediate precision. The limits of detection, quantification and practical, were 0.11, 0.35 and 1.56 ?g/ml, respectively. All compounded samples were approved with in the quality control; however, one generic and one similar sample presented above allowed level. PMID:25593388

Scherer, R; Pereira, Jessica; Firme, Juliete; Lemos, Mariana; Lemos, Mayara

2014-01-01

406

Kinetic spectrophotometric determination of Fe(II) in the presence of Fe(III) by H-point standard addition method in mixed micellar medium  

Microsoft Academic Search

The H-point standard addition method was applied to kinetic data for simultaneous determination of Fe(II) and Fe(III) or selective determination of Fe(II) in the presence of Fe(III). The method is based on the difference in the rate of complex formation between iron in two different oxidation states and methylthymol blue (MTB) at pH 3.5 in mixed cetyltrimethylammonium bromide (CTAB) and

Masoumeh Hasani; Alireza Rezaei; Hamid Abdollahi

2007-01-01

407

Study of Methods for Producing a Tunable UV Laser for Spectroscopy at 243nm.  

NASA Astrophysics Data System (ADS)

We are beginning an experiment to precisely measure the 1S to 2S interval in atomic tritium. A narrow bandwidth tunable source of several mW at 243nm is required. We seek methods that are less expensive and cumbersome than traditional dye or Ti Sapphire lasers. An all solid state approach has been demonstrated [Zimmermann, Vuletic, Hemmerich and Hansch, Appl. Phys. Lett. 66 p2318, 1995] using a MOPA semiconductor laser with two resonant doubling cavities using KNbO3 and BBO. We study this approach but with possible improvements using PPLN as an alternative to KNbO3 and using CLBO for doubling 486nm as an alternative to BBO. Other IR laser sources are also considered. The current status of our investigations will be presented

Khademian, Ali; Shiner, David

2002-05-01

408

Development of a rapid LC-UV method for the investigation of chemical and metabolic stability of resveratrol oligomers.  

PubMed

Resveratrol, piceatannol, ?-viniferin, r-viniferin, r2-viniferin, and hopeaphenol are naturally occurring polyphenols, associated with potentially beneficial health effects. We developed a rapid liquid chromatography-ultraviolet detection (LC-UV) method, allowing for the simultaneous determination of these six compounds in biological samples in less than 2.5 min with standard LC equipment. Using this method for the assessment of the stability of the six analytes, we demonstrated that all stilbene polyphenols disappear rapidly in Dulbecco's modified Eagle's medium (e.g., half-life of resveratrol of 1 h). In contrast, the tetramer hopeaphenol was stable over the maximum incubation time of 72 h. In incubations with liver microsomes, ?-viniferin was rapidly glucuronidated, although to a lower extent than resveratrol. Hopeaphenol was not glucuronidated at all. Given that glucuronidation is the major metabolic pathway for polyphenols, hopeaphenol might exhibit significantly different pharmacokinetic properties than other polyphenols. When chemical and metabolic stability as well as biological activity of hopeaphenol are taken together, these findings warrant further investigation of this polyphenol. PMID:22808987

Willenberg, Ina; Brauer, Wiebke; Empl, Michael T; Schebb, Nils Helge

2012-08-15

409

Spectrophotometric estimation of individual flavone glycosides in three Euphorbia species.  

PubMed

Two spectrophotometric methods (conventional and differential) are carried out for the estimation of flavone glycosides (hyperoside and/or kaempferol-3-beta-glucoside) in Euphorbia paralias L., and Euphorbia helioscopia L. The glycosides are extracted with methanol from the aerial parts of the different Euphorbia species, separated on silica gel chromatoplates, and eluted by refluxing with methanol (80%). The absorbance value (conventional method) and the delta absorbance value (differential method) of the prepared glycosidal solutions are measured. The results of both methods are of conveinent reproducibility. PMID:1161795

Abdel-Salam, N A; El-Sayed, M; Khafagy, S M

1975-06-01

410

New Diazo Coupling Reactions for Visible Spectrophotometric Determination of Alfuzosin in Pharmaceutical Preparations  

Microsoft Academic Search

Simple, rapid and sensitive spectrophotometric procedures were developed for the analysis of Alfuzosin hydrochloride (AFZ) in pure form as well as in pharmaceutical formulations. The methods are based on the reaction of AFZ with nitrite in acid medium to form diazonium ion, which is coupled with ethoxyethylenemaleic ester (Method A) or ethylcyanoacetate (Method B) or acetyl acetone (method C) in

M. VAMSI KRISHNA; D. GOWRI SANKAR

2007-01-01

411

FIA-Spectrophotometric Method for Determination of Nitrite in Meat Products: An Experiment Exploring Color Reduction of an Azo-Compound  

ERIC Educational Resources Information Center

This article describes the reaction between nitrite and safranine O. This sensitive reaction is based on the disappearance of color of the reddish-orange azo dye, allowing the determination of nitrite at the mg mL-1 level. A factorial optimization of parameters was carried out and the method was applied for the quantification of nitrite in…

Penteado, Jose C.; Angnes, Lucio; Masini, Jorge C.; Oliveira, Paulo C. C.

2005-01-01

412

Schrödinger method as N-body double and UV completion of dust  

NASA Astrophysics Data System (ADS)

We investigate large-scale structure formation of collisionless dark matter in the phase space description based on the Vlasov (or collisionless Boltzmann) equation whose nonlinearity is induced solely by gravitational interaction according to the Poisson equation. Determining the time evolution of density and peculiar velocity demands solving the full Vlasov hierarchy for the moments of the phase space distribution function. In the presence of long-range interaction no consistent truncation of the hierarchy is known apart from the pressureless fluid (dust) model, which is incapable of describing virialization due to the occurrence of shell-crossing singularities and the inability to generate vorticity and higher cumulants like velocity dispersion. Our goal is to find a simple ansatz for the phase space distribution function that approximates the full Vlasov distribution function without pathologies in a controlled way and therefore can serve as theoretical N-body double and as a replacement for the dust model. We argue that the coarse-grained Wigner probability distribution obtained from a wave function fulfilling the Schrödinger-Poisson equation (SPE) is the sought-after function. We show that its evolution equation approximates the Vlasov equation and therefore also the dust fluid equations before shell crossing, but cures the shell-crossing singularities and is able to describe regions of multistreaming and virialization. This feature was already employed in cosmological simulations of large-scale structure formation by Widrow and Kaiser (1993). The coarse-grained Wigner ansatz allows us to calculate all higher moments from density and velocity analytically, thereby incorporating nonzero higher cumulants in a self-consistent manner. On this basis we are able to show that the Schrödinger method automatically closes the corresponding hierarchy such that it suffices to solve the SPE in order to directly determine density and velocity and all higher cumulants.

Uhlemann, Cora; Kopp, Michael; Haugg, Thomas

2014-07-01

413

Synthetic Color Indices of Spectrophotometric Standards  

NASA Astrophysics Data System (ADS)

Synthetic B--V color indices in the {\\it WBVR photometric system for 11 stars of 3 -- 4 mag, proposed as spectrophotometric standards, are calculated for the mean energy distribution data from the Moscow and Alma-Ata spectrophotometric catalogs. Also, synthetic B--V color indices in the same photometric system are obtained for 16 stars of 6 -- 7 mag from the set of 60 spectrophotometric standards observed at the Sternberg Institute Crimean Station. Both sets of spectrophotometric standards demonstrate a good agreement between the synthetic and observed color indices. The energy distribution of Vega is compared with the mean energy distribution for A0 V-type stars. A pecularity of the energy distribution of Vega in the ultraviolet range is discussed.

Glushneva, I. N.

414

New spectrophotometric methods for the determinations of hydrogen sulfide present in the samples of lake water, industrial effluents, tender coconut, sugarcane juice and egg  

NASA Astrophysics Data System (ADS)

The new methods are working on the principle that iron(III) is reduced to iron(II) by hydrogen sulfide, catechol and p-toluidine the system 1/hydrogen sulfide the system 2, in acidic medium followed by the reduced iron forming complex with 1,10-phenanthroline with ?max 510 nm. The other two methods are based on redox reactions between electrolytically generated manganese(III) sulfate taken in excess and hydrogen sulfide followed by the unreacted oxidant oxidizing diphenylamine ?max 570 the system 3/barium diphenylamine sulphonate ?max 540 nm, the system 4. The increase/decrease in the color intensity of the dye products of the systems 1 and 2 or 3 and 4 are proportional to the concentration of hydrogen sulfide with its quantification range 0.035-1.40 ?g ml-1/0.14-1.40 ?g ml-1.

Shyla, B.; Nagendrappa, G.

2012-10-01

415

Quantitative determination of curcuminoids from the Roots of Curcuma longa, Curcuma species and dietary supplements using an UPLC-UV-MS method  

Technology Transfer Automated Retrieval System (TEKTRAN)

A simple, fast UPLC-UV-MS method was developed for the determination of curcuminoids from roots of Curcuma longa L., Curcuma species (C. zedoaria, C. phaecaulis, C. wenyujin and C. kwangsiensis) and dietary supplements claiming to contain C. longa. The total content of curcuminoids (curcumin, desmet...

416

A simplified 96-well method for the estimation of phenolic acids and antioxidant activity from eggplant pulp extracts using UV spectral scan data  

Technology Transfer Automated Retrieval System (TEKTRAN)

Eggplant fruit is ranked amongst the top ten vegetables in terms of oxygen radical absorbance capacity due to its high phenolic acid content. The main objective of this study was to determine if a simple UV spectral analysis method can be used as a screening tool to estimate the amount of phenolic ...

417

Simultaneous determination of the absolute configuration of twelve monosaccharide enantiomers from natural products in a single injection by UPLC-UV/MS method  

Technology Transfer Automated Retrieval System (TEKTRAN)

In natural product chemistry, it is often crucial to determine sugar composition as well as the absolute configuration of each monosaccharide in glycosides. An ultra-performance liquid chromatography method using both photodiode array (PDA) and mass spectrometry detectors (UPLC-UV/MS) was developed....

418

Simultaneous multicomponent spectrophotometric monitoring of methyl and propyl parabens using multivariate statistical methods after their preconcentration by robust ionic liquid-based dispersive liquid-liquid microextraction  

NASA Astrophysics Data System (ADS)

A powerful and efficient signal-preprocessing technique that combines local and multiscale properties of the wavelet prism with the global filtering capability of orthogonal signal correction (OSC) is applied for pretreatment of spectroscopic data of parabens as model compounds after their preconcentration by robust ionic liquid-based dispersive liquid-liquid microextraction method (IL-DLLME). In the proposed technique, a mixture of a water-immiscible ionic liquid (as extraction solvent) [Hmim][PF6] and disperser solvent is injected into an aqueous sample solution containing one of the IL's ions, NaPF6, as extraction solvent and common ion source. After preconcentration, the absorbance of the extracted compounds was measured in the wavelength range of 200-700 nm. The wavelet orthogonal signal correction with partial least squares (WOSC-PLS) method was then applied for simultaneous determination of each individual compound. Effective parameters, such as amount of IL, volume of the disperser solvent and amount of NaPF6, were inspected by central composite design to identify the most important parameters and their interactions. The effect of pH on the sensitivity and selectivity was studied according to the net analyte signal (NAS) for each component. Under optimum conditions, enrichment factors of the studied compounds were 75 for methyl paraben (MP) and 71 for propyl paraben (PP). Limits of detection for MP and PP were 4.2 and 4.8 ng mL-1, respectively. The root mean square errors of prediction for MP and PP were 0.1046 and 0.1275 ?g mL-1, respectively. The practical applicability of the developed method was examined using hygienic, cosmetic, pharmaceutical and natural water samples.

Khani, Rouhollah; Ghasemi, Jahan B.; Shemirani, Farzaneh

2014-03-01

419

Quantification of dissolved organic carbon at very low levels in natural ice samples by a UV-induced oxidation method.  

PubMed

The study of chemical impurities trapped in solid precipitation and accumulated in polar ice sheets and high-elevation, midlatitude cold glaciers over the last several hundreds of years provides a unique way to reconstruct our changing atmosphere from the preindustrial era to the present day. Numerous ice core studies of inorganic species have already evaluated the effects of growing anthropogenic emissions of SO(2) or NO(x) on the chemical composition of the atmosphere in various regions of the world. While it was recently shown that organic species dominate the atmospheric aerosol mass, the contribution of anthropogenic emissions to their budget remains poorly understood. The study of organics in ice is at the infancy stage, and it still is difficult to draw a consistent picture of the organic content of polar ice from sparse available data. A UV oxidation method and IR quantification of CO(2) was optimized to obtain measurements of dissolved organic carbon content as low as a few ppbC. Stringent working conditions were defined to prevent contamination during the cleaning of ice. Measurements in various ice cores corresponding to preindustrial times revealed dissolved organic carbon content of less than 10 ppbC in Antarctica and up to 75 ppbC in alpine ice. PMID:21142062

Preunkert, S; Legrand, M; Stricker, P; Bulat, S; Alekhina, I; Petit, J R; Hoffmann, H; May, B; Jourdain, B

2011-01-15

420

Spectrophotometric Determination of Sparfloxacin in Pharmaceutical Preparations by Ternary Complex Formation with Pd(II) and Eosin  

Microsoft Academic Search

A simple, sensitive, and direct spectrophotometric method has been developed for the assay of sparfloxacin in bulk and pharmaceutical preparations. The proposed method is based on the formation of ternary complex between an investigated drug, palladium(II) ion and eosin in the presence of methylcellulose as surfactant and acetate buffer of pH 4.2. Spectrophotometrically, under the optimum conditions, the ternary complex

2007-01-01