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1

UV Spectrophotometric Method for Determination of Phenacetin in Biological Specimens.  

National Technical Information Service (NTIS)

A UV spectrophotometric procedure for determining phenacetin in biological specimens is described. The drug is extracted from biological material by ether and oxidized to a quinone product by cobaltic oxide. The primary metabolite of phenacetin, N-acetyl-...

H. E. Hamilton J. D. Biggs J. E. Wallace K. Blum L. L. Foster

1973-01-01

2

Simultaneous Estimation of Esomeprazole and Domperidone by UV Spectrophotometric Method  

PubMed Central

A novel, simple, sensitive and rapid spectrophotometric method has been developed for simultaneous estimation of esomeprazole and domperidone. The method involved solving simultaneous equations based on measurement of absorbance at two wavelengths, 301 nm and 284 nm, ? max of esomeprazole and domperidone respectively. Beer's law was obeyed in the concentration range of 5-20 ?g/ml and 8-30 ?g/ml for esomeprazole and domperidone respectively. The method was found to be precise, accurate, and specific. The proposed method was successfully applied to estimation of esomeprazole and domperidone in combined solid dosage form.

Prabu, S. Lakshmana; Shirwaikar, A.; Shirwaikar, Annie; Kumar, C. Dinesh; Joseph, A.; Kumar, R.

2008-01-01

3

Determination of lornoxicam in pharmaceutical preparations by zero and first order derivative UV spectrophotometric methods.  

PubMed

Zero and first order derivative UV spectrophotometric methods were developed for the analysis of lornoxicam (LOR). The solutions of the standards and pharmaceutical samples were prepared in 0.05 N NaOH. Absorbances of LOR were measured at 376 nm for the zero order by measuring height of peak from zero and at 281 and 302 nm for the first order derivative spectrophotometric method by measuring peak to peak height. The linearity ranges were found to be 0.5-35 microg/mL for the zero order and 0.2-75 microg/mL for the first order derivative UV spectrophotometric method. The methods were validated and applied to the determination of LOR in pharmaceutical preparations (tablet and injectable, both containing 8 mg LOR). It was concluded that the methods developed were accurate, sensitive, precise, robust, rugged and useful for the quality control of LOR in pharmaceutical preparations. PMID:15997830

Nemutlu, E; Demircan, S; Kir, S

2005-06-01

4

UV and Three Derivative Spectrophotometric Methods for Determination of Ezetimibe in Tablet Formulation.  

PubMed

UV, first, second and third derivative spectrophotometric methods have been developed for the determination of ezetimibe in pharmaceutical formulation. The solutions of standard and sample were prepared in methanol. For the first method, UV spectrophotometry, the quantitative determination of the drug was carried at 233 nm and the linearity range was found to be 6-16 mug/ml. For the first, second and third derivative spectrophotometric methods the drug was determined at 259.5 nm, 269 nm and 248 nm with the linearity ranges 4-14 mug/ml, 4-14 mug/ml and 4-16 mug/ml. The calibration graphs constructed at their wavelength of determination were found to be linear for UV and derivative spectrophotometric methods. All the proposed methods have been extensively validated. The described methods can be readily utilized for the analysis of pharmaceutical formulation. There was no significant difference between the performance of the proposed methods regarding the mean values and standard deviations. PMID:20046728

Sharma, Metreyi; Mhaske, Deepali V; Mahadik, M; Kadam, S S; Dhaneshwar, S R

5

UV and Three Derivative Spectrophotometric Methods for Determination of Ezetimibe in Tablet Formulation  

PubMed Central

UV, first, second and third derivative spectrophotometric methods have been developed for the determination of ezetimibe in pharmaceutical formulation. The solutions of standard and sample were prepared in methanol. For the first method, UV spectrophotometry, the quantitative determination of the drug was carried at 233 nm and the linearity range was found to be 6-16 ?g/ml. For the first, second and third derivative spectrophotometric methods the drug was determined at 259.5 nm, 269 nm and 248 nm with the linearity ranges 4-14 ?g/ml, 4-14 ?g/ml and 4-16 ?g/ml. The calibration graphs constructed at their wavelength of determination were found to be linear for UV and derivative spectrophotometric methods. All the proposed methods have been extensively validated. The described methods can be readily utilized for the analysis of pharmaceutical formulation. There was no significant difference between the performance of the proposed methods regarding the mean values and standard deviations.

Sharma, Metreyi; Mhaske, Deepali V.; Mahadik, M.; Kadam, S. S.; Dhaneshwar, S. R.

2008-01-01

6

Application of UV-spectrophotometric methods for estimation of tenofovir disoproxil fumarate in tablets.  

PubMed

Two new, simple and cost effective UV-spectrophotometric and first order derivative methods were developed for estimation of tenofovir disoproxil fumarate in bulk and tablets. Tenofovir disoproxil fumarate was estimated at 260 nm in 0.1N HCl. In first order derivative, it showed amplitude at 273 nm. In both the methods linearity was found to be in the range of 5-40 micro/ ml; for UV-spectrophotometric method (Y=0.02586 x +0.0083; r(2)=0.9999) and for first order derivative spectrophotometric method (Y=0.00132 x +0.00035; r(2)=0.9995), respectively. These methods were tested and validated for various parameters according to USP guidelines. The quantitation limits were found to be 1.546 and 1.986 micro/ ml, for both the methods. The proposed methods were successfully applied for the determination of tenofovir disoproxil fumarate in pharmaceutical formulations. The results demonstrated that the procedure is accurate, precise and reproducible (relative standard deviation <2%), while being simple, cheap and less time consuming and can be suitably applied for the estimation of tenofovir disoproxil fumarate in different dosage forms. PMID:19168416

A, Shirkhedkar Atul; H, Bhirud Charushila; J, Surana Sanjay

2009-01-01

7

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

8

Development and validation of liquid chromatographic and UV derivative spectrophotometric methods for the determination of famciclovir in pharmaceutical dosage forms.  

PubMed

A high-performance liquid chromatographic method and a UV derivative spectrophotometric method for the determination of famciclovir, a highly active antiviral agent, in tablets were developed in the present work. The various parameters, such as linearity, precision, accuracy, specificity, robustness, limit of detection and limit of quantitation were studied according to International Conference on Harmonization guidelines. HPLC was carried out by using the reversed-phase technique on an RP-18 column with a mobile phase composed of 50 mM monobasic phosphate buffer and methanol (50 : 50; v/v), adjusted to pH 3.05 with orthophosphoric acid. The mobile phase was pumped at a flow rate of 1 ml/min and detection was made at 242 nm with UV dual absorbance detector. The first derivative UV spectrophotometric method was performed at 226.5 nm. Statistical analysis was done by Student's t-test and F-test, which showed no significant difference between the results obtained by the two methods. The proposed methods are highly sensitive, precise and accurate and therefore can be used for its Intended purpose. PMID:16755050

Srinubabu, Gedela; Sudharani, Batchu; Sridhar, Lade; Rao, Jvln Seshagiri

2006-06-01

9

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

10

Chlorine Dioxide-Iodide-Methyl Acetoacetate Oscillation Reaction Investigated by UV-Vis and Online FTIR Spectrophotometric Method  

PubMed Central

In order to study the chemical oscillatory behavior and mechanism of a new chlorine dioxide-iodide ion-methyl acetoacetate reaction system, a series of experiments were done by using UV-Vis and online FTIR spectrophotometric method. The initial concentrations of methyl acetoacetate, chlorine dioxide, potassium iodide, and sulfuric acid and the pH value have great influence on the oscillation observed at wavelength of 289?nm. There is a preoscillatory or induction period, and the amplitude and the number of oscillations are associated with the initial concentration of reactants. The equations for the triiodide ion reaction rate changing with reaction time and the initial concentrations in the oscillation stage were obtained. Oscillation reaction can be accelerated by increasing temperature. The apparent activation energies in terms of the induction period and the oscillation period were 26.02?KJ/mol and 17.65?KJ/mol, respectively. The intermediates were detected by the online FTIR analysis. Based upon the experimental data in this work and in the literature, a plausible reaction mechanism was proposed for the oscillation reaction.

Shi, Laishun; Wang, Xiaomei; Li, Na; Liu, Jie; Yan, Chunying

2012-01-01

11

Chlorine dioxide-iodide-methyl acetoacetate oscillation reaction investigated by UV-vis and online FTIR spectrophotometric method.  

PubMed

In order to study the chemical oscillatory behavior and mechanism of a new chlorine dioxide-iodide ion-methyl acetoacetate reaction system, a series of experiments were done by using UV-Vis and online FTIR spectrophotometric method. The initial concentrations of methyl acetoacetate, chlorine dioxide, potassium iodide, and sulfuric acid and the pH value have great influence on the oscillation observed at wavelength of 289?nm. There is a preoscillatory or induction period, and the amplitude and the number of oscillations are associated with the initial concentration of reactants. The equations for the triiodide ion reaction rate changing with reaction time and the initial concentrations in the oscillation stage were obtained. Oscillation reaction can be accelerated by increasing temperature. The apparent activation energies in terms of the induction period and the oscillation period were 26.02?KJ/mol and 17.65?KJ/mol, respectively. The intermediates were detected by the online FTIR analysis. Based upon the experimental data in this work and in the literature, a plausible reaction mechanism was proposed for the oscillation reaction. PMID:22454614

Shi, Laishun; Wang, Xiaomei; Li, Na; Liu, Jie; Yan, Chunying

2012-02-01

12

UV Spectrophotometric Method for Assay of the Anti-Retroviral Agent Lamivudine in Active Pharmaceutical Ingredient and in its Tablet Formulation  

PubMed Central

A rapid, simple, accurate, and economical spectrophotometric method has been developed and validated for the assay of the anti-retroviral agent lamivudine in active pharmaceutical ingredients (API) and in its tablet formulation. The analysis is based on the UV absorbance maxima at about 270nm wavelength of lamivudine, using methanol as solvent. A sample of API was dissolved in methanol to produce a solution containing 10 µg/mL of lamivudine. Similarly, a sample of ground tablets were extracted with methanol, centrifuged, and diluted with the same solvent. The absorbance of the sample preparation was measured at 270 nm against the solvent blank, and the assay was determined by comparing with the absorbance of a similarly prepared 10 µg/mL standard solution of lamivudine. The calibration graph was rectilinear from 5 µg/mL to 15 µg/mL for lamivudine with the correlation coefficient being more than 0.999. The relative standard deviation of the replicate determination was about 0.5%. The percent recovery was within the range of 98%–102%, indicating insignificant interference from the other ingredients in the formulation. The method can be applied for the routine QC quantitation of lamivudine in API and tablet formulation.

Deepali, G; Elvis, M

2010-01-01

13

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

14

FTIR spectrophotometric methods used for antioxidant activity assay IN MEDICINAL PLANTS  

Microsoft Academic Search

Fourier transform infrared spectroscopy (FTIR) is a fast and nondestructive analytical method. Associated with chemometrics, it is a powerful tool for research and industry. The present review discusses the antioxidant activities assay of some plants (fruits, leaves, aerian part) having medical properties using FTIR spectrophotometric method in comparison with other UV-VIS different spectrophotometric methods. A good correlation was found between

Andrei A. Bunaciu; Hassan Y. Aboul-Enein; Serban Fleschin

2012-01-01

15

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

16

A new spectrophotometric method for measuring COD of seawater  

NASA Astrophysics Data System (ADS)

This research studied a new spectrophotometric method for measuring the chemical oxygen demand (COD) of seawater. In this method, the COD was measured using a spectrophotometer instead of titrating with sodium thiosulphate. The measuring wavelength was selected to be 470 nm, and the COD of three standard glucose solutions (COD=0.5, 1.5 and 2.5 mgL-1, respectively) and two seawater samples (from the South Yellow Sea and Jiaozhou Bay) were measured using the spectrophotometric method and titrimetric method respectively. The results showed that the spectrophotometric method was somewhat better than the titrimetric method. The relative standard deviation (RSD) of the spectrophotometric method was less than 2.7%, and the recovery of seawater samples ranged from 96.3% to 103.8%. In addition, the spectrophotometric method has other advantages such as expeditiousness, operation simplicity, analysis automatization, etc. Therefore the spectrophotometric method can be used to measure the COD of seawater with satisfactory results.

Liu, Ying; Ji, Hongwei; Xin, Huizhen; Liu, Li

2006-04-01

17

Determination of total chromium traces in tannery effluents by electrothermal atomic absorption spectrometry, flame atomic absorption spectrometry and UV-visible spectrophotometric methods.  

PubMed

Three different analytical methods comprising colorimetric method with 1,5-diphenyl-carbazide, electrothermal atomic absorption spectrometry (ET AAS) and flame atomic absorption spectrometry were utilized in a study to determine traces of chromium (Cr) in synthetic tannery effluent from laboratory scale treatment process variations. All the results obtained using the three different methods showed good agreement and met the requirement of Brazilian regulation for total Cr for effluent discharges (<0.5 mg l(-1)). However, ET AAS has been the proposed method because it was faster, less laborious, needed smaller volume of sample and presented lower limit of quantification (LOQ=2.2 mug l(-1)). PMID:18968791

Monteiro, M I C; Fraga, I C S; Yallouz, A V; de Oliveira, N M M; Ribeiro, S H

2002-10-16

18

PLS-UV Spectrophotometric Method for the Simultaneous Determination of Ternary Mixture of Sweeteners (Aspartame, Acesulfame-K and Saccharin) in Commercial Products  

Microsoft Academic Search

Aspartame (Apt), Acesulfame-K (Ace-K) and Saccharin (Sac), low-calorie, high-potency artificial sweeteners are currently\\u000a used in carbonated beverages, dietary food and drinks. Their increased application in food and drink products has given a\\u000a new impetus to develop fast and accurate methods for their determination. Absorption spectra of Apt, Ace-K and Sac strongly\\u000a overlap. Therefore a direct determination of these analytes in

Fatma Turak; Mahmure Üstün Özgür; Abdürrezzak Bozdo?an

19

Quantitative Determination of Ciprofibrate in Tablets by Derivative UV Spectroscopy and RP-HPLC Method  

PubMed Central

A derivative UV spectrophotometric and a reversed phase high-performance liquid chromatographic method for the determination of ciprofibrate in tablets was developed. The first-order derivative UV spectrophotometric method was found to be accurate with 100.57±0.97 recovery and precise with a coefficient of variation of 1.44. These results were compared to those obtained by reference methods, zero-order UV spectrophotometric method and a reversed-phase high-performance liquid chromatography method. A reversed-phase C8 column with methanol:water (90:10, v/v, pH 3.7) mobile phase was used and the detector wavelength was set at 232 nm. Calibration solutions used in HPLC were ranging from 2 to 12 ?g/ml. An ANOVA test (P = 0.0226, F = 4.935) showed that the results obtained with the derivative UV spectrophotometric method were comparable to those obtained using reference methods.

Jain, P. S.; Jivani, H. N.; Khatal, R. N.; Surana, S. J.

2012-01-01

20

Quantitative Determination of Ciprofibrate in Tablets by Derivative UV Spectroscopy and RP-HPLC Method.  

PubMed

A derivative UV spectrophotometric and a reversed phase high-performance liquid chromatographic method for the determination of ciprofibrate in tablets was developed. The first-order derivative UV spectrophotometric method was found to be accurate with 100.57±0.97 recovery and precise with a coefficient of variation of 1.44. These results were compared to those obtained by reference methods, zero-order UV spectrophotometric method and a reversed-phase high-performance liquid chromatography method. A reversed-phase C(8) column with methanol:water (90:10, v/v, pH 3.7) mobile phase was used and the detector wavelength was set at 232 nm. Calibration solutions used in HPLC were ranging from 2 to 12 ?g/ml. An ANOVA test (P = 0.0226, F = 4.935) showed that the results obtained with the derivative UV spectrophotometric method were comparable to those obtained using reference methods. PMID:23326000

Jain, P S; Jivani, H N; Khatal, R N; Surana, S J

2012-03-01

21

Simple spectrophotometric methods for standardizing ayurvedic formulation.  

PubMed

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

2012-03-01

22

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.

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

2012-01-01

23

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.

Zoltan, Tamara; Vargas, Franklin; Izzo, Carla

2007-01-01

24

Spectrophotometric and HPLC Methods for Simultaneous Estimation of Amlodipine Besilate, Losartan Potassium and Hydrochlorothiazide in Tablets  

PubMed Central

Two UV-spectrophotometric and one reverse phase high performance liquid chromatography methods have been developed for the simultaneous estimation of amlodipine besilate, losartan potassium and hydrochlorothiazide in tablet dosage form. The first UV spectrophotometric method was a determination using the simultaneous equation method at 236.5, 254 and 271 nm over the concentration range 5-25, 10-50 and 5-25 ?g/ml for amlodipine besilate, losartan potassium and hydrochlorothiazide, respectively. The second UV method was a determination using the area under curve method at 231.5-241.5, 249-259 and 266-276 nm over the concentration range of 5-25, 5-25 and 10-50 ?g/ml for amlodipine besilate, hydrochlorothiazide and losartan potassium, respectively. In reverse phase high performance liquid chromatography analysis is carried out using 0.025 M phosphate buffer (pH 3.7):acetonitrile (57:43 v/v) as the mobile phase and Kromasil C18 (4.6 mm i.d×250 mm) column as stationery phase with detection wavelength of 232 nm linearity was obtained in the concentration range of 2-14, 20-140 and 5-40 ?g/ml for amlodipine besilate, losartan potassium and hydrochlorothiazide, respectively. Both UV-spectrophotometric and reverse phase high performance liquid chromatography methods were statistically validated and can be used for analysis of combined dose tablet formulation containing amlodipine besilate, losartan potassium and hydrochlorothiazide.

Wankhede, S. B.; Raka, K. C.; Wadkar, S. B.; Chitlange, S. S.

2010-01-01

25

Extractive spectrophotometric methods for determination of lercanidipine.  

PubMed

Extractive spectrophotometric methods are described for the determination of lercanidipine (LER) either in pure form or in pharmaceutical formulations. The methods involve formation of coloured chloroform extractable ion-pair complexes with bromothymol blue (BTB) and bromocresol green (BCG) in acidic medium. The extracted complexes showed absorbance maxima at 417 and 416 nm for BTB and BCG, respectively. The optimization of the reaction conditions was investigated. Beer's law is obeyed in the concentration ranges 6.0-42.0 microg x ml(-1) or 7.1-43.8 microg x ml(-1) with BTB or BCG, respectively. The composition of the ion-pairs was found to be 1:1 by Job's method. The specific absorptivities, molar absorptivities, Sandell sensitivities, standard deviations and percent recoveries were evaluated. Also, LER was determined by measurement of its first derivative signals at 245 nm. Calibration graph was established for 4.2-58.0 microg x ml(-1) of LER. The methods have been applied to the determination of drug in commercial tablets. Results of analysis were validated. No interferences were observed from common pharmaceutical adjuvants. PMID:14664335

Erk, Nevin

2003-11-01

26

Colour Testing of Nitrocellulose Propellants by a Spectrophotometric Method.  

National Technical Information Service (NTIS)

The colour test is a test for chemical stability that can be applied to many of the nitrocellulose propellants stabilized with ethyl centralite. A spectrophotometric method has been developed for carrying out this test and for the preparation and checking...

R. M. Kempson

1983-01-01

27

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

PubMed

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 (r (2)= 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

2011-04-01

28

Determination of Theobromine, Theophylline, and Caffeine in Various Food Products Using Derivative UV-Spectrophotometric Techniques and High-Performance Liquid Chromatography  

Microsoft Academic Search

Accurate, sensitive and precise derivative ultraviolet Spectrophotometric and high-performance liquid chromatographic (HPLC) methods are described for the simultaneous determination of three natural methyl xanthines (theobromine, theophylline and caffeine) in various food products. The derivative UV-spectro-photometry, with zero crrosing technique of measurement was selected for determination of theobromine and theophylline. First-derivative procedure (D1) was adopted for theobromine determination in the presence

Mustafa A. Abuirjeie; Mohie Sharaf El-Din; Ibrahim I. Mahmoud

1992-01-01

29

Production control of nitroxoline by spectrophotometric method  

Microsoft Academic Search

Data of the spectrophotometric determination of 8-hydroxyquinoline are given in Table i. Determination Procedure. Approximately 0.2 g of the 8-hydroxyquinoline paste (accurately weighed) is placed in a i00 ml volumetric flask and dissolved in I0 ml of alcohol and the water is added up to the mark. A 1 ml portion of the solution is tbln placed in a 200

L. I. Koloskova; I. I. Dozorova; T. K. Filatova

1978-01-01

30

Development and validation of spectrophotometric method of cefpodoxime proxetil using hydrotropic solubilizing agents  

PubMed Central

Purpose: To develop and validate specific and accurate UV spectrophotometric method of cefpodoxime proxetil by using different hydrotropic solubilizing agents. Materials and Methods: The present study deals with spectrophotometric analysis of cefpodoxime proxetil by utilizing 4 different hydrotropic agents such as ammonium acetate (6 M), sodium citrate (1.25 M), sodium gycinate (1 M), sodium chloride (1 M), and urea (1 M). Results: From different hydrotropic agents, urea showed best aqueous solubility of cefpodoxime proxetil. The linearity was observed in the concentration range of 10-120 ?g/ml. The method was validated and found to be precise. Accuracy (percent recovery) for cefpodoxime proxetil was found to be 99.82 ± 0.106. Conclusion: Urea as hydrotropic agent showed best aqueous solubility of cefpodoxime proxetil, which can be used as solubilizing agent. The proposed method is new, simple, safe, eco-friendly, economic, accurate, and cost-effective and can be successfully employed in routine analysis.

Asnani, Geet; Jadhav, Kiran; Dhamecha, Dinesh; Sankh, Ashwini; Patil, Mrityunjaya

2012-01-01

31

Kinetic spectrophotometric methods for determination of trimetazidine dihydrochloride  

Microsoft Academic Search

Four simple and sensitive kinetic spectrophotometric methods (I–IV) for the determination of trimetazidine dihydrochloride (TRMZ) have been developed. Method I was based on the oxidation of the drug with alkaline KMnO4 producing green manganate species. Method II was based on the formation of colored condensation product between TRMZ and 4-chloro-7-nitrobenzofurazan (NBD-Cl). Method III was based on reaction of TRMZ and

Ibrahim A. Darwish

2005-01-01

32

Second order derivative spectrophotometric method for determination of vitamin C content in fruits, vegetables and fruit juices  

Microsoft Academic Search

A second-order derivative UV spectrophotometric method for determination of vitamin C [ascorbic acid (AA)] content in a variety of natural samples is described. The method is based on the measurement of a peak–baseline amplitude in the second derivative of the AA spectrum at 267.5 nm. The following corresponding regression equation was obtained within the concentration range 2×10 -5 to 1×10 -4 M

Lidija B. Pfendt; Vesna L. Vukašinovic; Nada Z. Blagojevic; Mirjana P. Radojevic

2003-01-01

33

Comparison of second derivative-spectrophotometric and reversed-phase HPLC methods for the determination of prednisolone in pharmaceutical formulations.  

PubMed

Second derivative-spectrophotometric and high-performance liquid chromatographic methods for the determination of prednisolone in pharmaceutical formulations have been developed. Determination of prednisolone in tablets was conducted by using a second-order derivative UV spectrophotometric method at 250 nm (n = 5). Standards for the calibration graph ranging from 5.0 to 35.0 microg/ml were prepared from stock solution. The proposed method was accurate, with 98% recovery value, and precise, with a coefficient of variation (CV) of 1.38. These results were compared with those obtained by an exclusively developed isocratic reversed-phase high-performance liquid chromatography (HPLC) method. An isocratic reversed-phase Bondapak C(18) column with acetonitrile-citrophosphate buffer (pH 5; 45:55 v/v) mobile phase was used and UV detector was set to 241 nm using 11 alpha-hydroxyprogesterone as an internal standard. Calibration solutions used in HPLC were in the range from 2 to 300 microg/ml. Results obtained by derivative UV spectrophotometric method were comparable to those obtained by HPLC method, as far as analysis of variance (ANOVA) test, F(calculated), 0.762 and F(theoretical), 3.89, results were concerned. PMID:17928675

Singh, D K; Verma, Rohan

2007-10-01

34

Comparison of derivative spectrophotometric and liquid chromatographic methods for the determination of rofecoxib.  

PubMed

Two different UV spectrophotometric methods were developed for the determination of rofecoxib in bulk form and in pharmaceutical formulations. The first method, an UV spectrophotometric procedure, was based on the linear relationship between the rofecoxib concentration and the lambdamax amplitude at 279 nm. The second one, the first derivative spectrophotometry, was based on the linear relationship between the rofecoxib concentration and the first derivative amplitude at 228, 256 and 308 nm. Calibration curves were linear in the concentration range using peak to zero 1.5-35.0 microg x ml(-1). HPLC was carried out at 225 nm with a partisil 5 ODS (3) column and a mobile phase constituted of acetonitrile and water (50 :50 v/v). A linear range was found to be 0.05-35.0 microg x ml(-1). The developed methods were successfully applied for the assay of pharmaceutical dosage form. The statistics of the analytical data is also presented. The results obtained by first derivative spectrophotometry were compared with HPLC and no significant difference was found. PMID:15248460

Erk, N; Altuntas, T G

2004-06-01

35

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.

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

2011-01-01

36

Visible spectrophotometric method for the determination of aripiprazole in tablets.  

PubMed

A simple, accurate and economic spectrophotometric method for the determination of aripiprazole in tablet formulation is proposed. In the present method acidic solution of the aripiprazole formed colored ion-association complexes with bromocresol green, soluble in chloroform. Yellowish orange chromogen showed ?(max) at 414 nm and obeyed Beer's law in the concentration range of 10-60 ?g/ml. Statistical analysis and recovery studies validated the method. The proposed method is rapid, precise and accurate and can be applied for the routine estimation of aripiprazole in the laboratory. PMID:22131625

Jain, R; Kashaw, S K; Jain, Rishab; Mishra, P; Kohli, D V

2011-01-01

37

HPLC and chemometric-assisted spectrophotometric methods for simultaneous determination of atenolol, amiloride hydrochloride and chlorthalidone.  

PubMed

Three methods are presented for the simultaneous determination of atenolol (AT), amiloride hydrochloride (AM) and chlorthalidone (CD). The high performance liquid chromatographic (HPLC) method depends on the separation of each drug on a reversed phase, RP (18) column. Elution was carried out with a mobile phase consisting of acetonitrile -5mM heptansulphonic acid sodium salt (20:80, v/v, pH 4.4). Quantitation was achieved with UV detection at 274 nm based on peak area. The other two-chemometric-assisted spectrophotometric methods applied were principal component regression (PCR) and partial least squares (PLS-1). These approaches were successfully applied to quantify each drug in the mixture using the information included in the absorption spectra of appropriate solutions in the range 240-290 nm with the intervals Deltalambda=0.2 nm. The three methods were successfully applied to a pharmaceutical formulation (tablets), and the results were compared with each other. PMID:15784248

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

2005-03-01

38

Spectrophotometric and liquid chromatographic determination of fenofibrate and vinpocetine and their hydrolysis products  

Microsoft Academic Search

Several spectrophotometric and HPLC methods are presented for the determination of fenofibrate, vinpocetine and their hydrolysis products. The resolution of either fenofibrate or vinpocetine and their hydrolysis products has been accomplished by using numerical spectrophotometric methods as partial least squares (PLS-1) and principal component regression (PCR) applied to UV spectra; and graphical spectrophotometric methods as first derivative of ratio spectra

Alaa El-Gindy; Samy Emara; Mostafa K. Mesbah; Ghada M. Hadad

2005-01-01

39

Quantitative determination of chloride by means of flow injection analysis with spectrophotometric detection in the UV\\/VIS range  

Microsoft Academic Search

Chloride is determined indirectly by Spectrophotometric flow injection analysis. Two systems are compared, both based on the principle of ion exchange of easily detectable anions versus chloride from suitable mercury salts. The first method is based on the exchange of chloride with chloranilate which is detected at 332 nm or at 306 nm in neutral or in acidic medium respectively.

Dietmar Krämer; Erwin Rosenberg; Achim Krug; Robert Kellner; Wolfgang Hutter; Werner Hampel

1994-01-01

40

A Novel Spectrophotometric Method for the Determination Oxacillin Sodium  

PubMed Central

A simple and sensitive spectrophotometric method was developed for the determination of Oxacillin sodium. The method was based on charge transfer complexation reaction of the drug with iodine in methanol – dichloromethane medium. The absorbance was measured at 365 nm against the reagent blank. Under optimized experimental conditions, Beer’s law is obeyed in the concentration ranges 2–8 ?g/ml for Oxacillin Sodium. The method was validated for specificity, linearity, precision, accuracy, limit of quantitation, robustness and ruggedness. The LOD and LOQ value were 0.39 and 1.18 ?g/ml respectively. The method was successfully applied to the analysis of Oxacillin sodium in Human Urine samples with good accuracy and precision.

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

2009-01-01

41

Extractive Spectrophotometric Method for the Determination of Tropicamide  

PubMed Central

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.

Shoaibi, ZA; Gouda, AA

2012-01-01

42

Determination of platelet monoamine oxidase by new continuous spectrophotometric method.  

PubMed

A simple, continuous spectrophotometric method for the determination of tissue monoamine oxidase based on the oxidation of 2,2'-azino-di-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) using peroxidase has already been described (Ivanovi?, I. & Majki?-Singh, N. (1986) Fresenius Z. Anal. Chem. 324, 307). In the present study the method is optimised for platelet monoamine oxidase assay and applied to healthy persons and schizophrenic patients. The obtained data were statistically analysed. The continuous ABTS method is sensitive, precise (CV below 6.9%) and linear up to 83 U/g protein. Comparison with the end-point method of Szutowicz et al. (1984) Anal. Biochem. 138, 86-94) gave a good correlation (r = 0.983). The reference values for the activity of human platelet monoamine oxidase by the new continuous ABTS method are 25 to 42 U/g protein (means = 33.2 U/g protein, CV = 15.5%, n = 67). No differences were found between females and males, or between three age groups ranging from 21 to 52 years. The patients with chronic (n = 76) or acute (n = 17) schizophrenia had significantly lower monoamine oxidase activities compared with normal values (p less than 0.005), which indicates that platelet monoamine oxidase can be a possible marker for schizophrenic diseases. PMID:3221175

Ivanovi?, I D; Majki?-Singh, N

1988-07-01

43

Spectrophotometric analysis of Ellerman bombs in the Ca II, H?, and UV range  

NASA Astrophysics Data System (ADS)

Context: Even if Ellerman bombs have been observed in the H? line within emerging magnetic flux regions since the early 20th century, their origin and the mechanisms that lead to their formation have been strongly debated. Recently, new arguments in favor of chromospheric magnetic reconnection have been advanced. Ellerman bombs seem to be the signature of reconnections that take place during the emergence of the magnetic field. Aims: We have observed an active region presenting emergence of magnetic flux. We detected and studied Ellerman bombs in two chromospheric lines: Ca ii 8542 Å and H?. We investigated the link between Ellerman bombs and other structures and phenomena appearing in an emerging active region: UV bright points, arch filament systems, and magnetic topology. Methods: On August 3, 2004, we performed multi-wavelength observations of the active region NOAA 10655. This active region was the target of SoHO Joint Observation Program 157. Both SoHO/MDI and TRACE (195 Å and 1600 Å) were used. Simultaneously, we observed in the Ca ii and Na D1 lines with the spectro-imager MSDP mode of THEMIS. Alternately to the MSDP, we used the MTR spectropolarimeter on THEMIS to observe in H? and in the Fe i doublet at 6302 Å. We derived the magnetic field vectors around some Ellerman bombs. Results: We present the first images of EBs in the Ca ii line and confirm that Ellerman bombs can indeed be observed in the Ca ii line, presenting the same “moustache” geometry profiles as in the H? line, but with a narrower central absorption in the Ca ii line, in which the peaks of emission are around ±0.35 Å. We noticed that the Ellerman bombs observed in the wings of Ca ii line have an elongated shape - the length about 50% greater than the width. We derived mean semi-axis lengths of 1.4'' × 2.0''. In the UV time profiles of the Ellerman bombs, we noticed successive enhanced emissions. The distribution of lifetimes of these individual impulses presents a strong mode around 210 s. Study of the magnetic topology shows that 9 out of the 13 EBs are located on the inversion line of the longitudinal field and that some typical examples might be associated with a bald patch topology. Conclusions: We provide new arguments in favor of the reconnection origin of Ellerman bombs. The different individual impulses observed in UV may be related to a bursty mode of reconnection. We also show that this Ca ii 8542 Å chromospheric line is a good indicator of Ellerman bombs and can bring new information about these phenomena.

Pariat, E.; Schmieder, B.; Berlicki, A.; Deng, Y.; Mein, N.; López Ariste, A.; Wang, S.

2007-10-01

44

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

45

Validated spectrophotometric method for the determination, spectroscopic characterization and thermal structural analysis of duloxetine with 1,2-naphthoquinone-4-sulphonate  

NASA Astrophysics Data System (ADS)

A novel, selective, sensitive and simple spectrophotometric method was developed and validated for the determination of the antidepressant duloxetine hydrochloride in pharmaceutical preparation. The method was based on the reaction of duloxetine hydrochloride with 1,2-naphthoquinone-4-sulphonate (NQS) in alkaline media to yield orange colored product. The formation of this complex was also confirmed by UV-visible, FTIR, 1H NMR, Mass spectra techniques and thermal analysis. This method was validated for various parameters according to ICH guidelines. Beer's law is obeyed in a range of 5.0-60 ?g/mL at the maximum absorption wavelength of 480 nm. The detection limit is 0.99 ?g/mL and the recovery rate is in a range of 98.10-99.57%. The proposed methods was validated and applied to the determination of duloxetine hydrochloride in pharmaceutical preparation. The results were statistically analyzed and compared to those of a reference UV spectrophotometric method.

Ulu, Sevgi Tatar; Elmali, Fikriye Tuncel

2012-03-01

46

UV\\/VIS Spectrophotometric Studies on the Antileukemic Agent Glyoxal bis(Amidinohydrazone) ['Glyoxal bis(Guanylhydrazone)'  

Microsoft Academic Search

Glyoxal bis(amidinohydrazone) (GBG) and several analogs thereof are compounds of considerable pharmacological interest, and a variety of HPLC and MECC methods have been developed for their analysis. In these methods, detection is invariably based on the strong UV absorption of the compound. Yet, almost nothing has been known of their UV and VIS spectral properties. In the present paper the

Mikko Koskinen; Hannu Elo

1994-01-01

47

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

2010-10-08

48

Extractive spectrophotometric methods for determination of zolmitriptan in tablets.  

PubMed

Two simple and sensitive extractive spectrophotometric methods have been developed for determination of zolmitriptan (ZTP) in tablets. These methods are based on the formation of yellow ion-pair complexes between ZTP and tropaeolin OO (TPOO) and bromothymol blue (BTB) in citrate-phosphate buffer of pH 4.0 and 6.0, respectively. The formed complexes were extracted with dichloromethane and measured at 411.5 and 410 nm for TPOO and BTB, respectively. The best conditions of the reactions were studied and optimized. Beer's law was obeyed in the concentration ranges of 2-20 and 1.5-17 microg/mL with molar absorptivities of 1.42 x 10(4) and 1.60 x 10(4) L/mol/cm for the TPOO and BTB methods, respectively. Correlation coefficients were 0.9998 and 0.9999 for TPOO and BTB methods, respectively. Limits of detection of the TPOO and BTB methods were 0.341 and 0.344 microg/mL, respectively, and the limits of quantitation were 1.034 and 1.051 microg/mL, respectively. Sandell's sensitivity and stability constant were also calculated. The proposed methods have been applied successfully for the analysis of the drug in its dosage forms. No interference was observed from excipients present in tablets. Statistical comparison of the results with those obtained by a high-performance liquid chromatography method showed excellent agreement and indicated no significant differences in accuracy and precision. PMID:17955967

Aydogmus, Zeynep; Inanli, Ipek

49

A simple Ultraviolet spectrophotometric method for the determination of etoricoxib in dosage formulations.  

PubMed

The present study was undertaken to develop a validated, rapid, simple, and low-cost ultraviolet (UV) spectrophotometric method for estimating Etoricoxib (ETX) in pharmaceutical formulations. The analysis was performed on ? max 233 nm using 0.1 M HCl as blank/diluent. The proposed method was validated on International Conference on Harmonization (ICH) guidelines including parameters as linearity, accuracy, precision, reproducibility, and specificity. The proposed method was also used to access the content of the ETX in two commercial brands of Indian market. Beer's law was obeyed in concentration range of 0.1-0.5 ?g/ml, and the regression equation was Y = 0.418x + 0.018. The mean accuracy values for 0.1 ?g/ml and 0.2 ?g/ml concentration of ETX were found to be 99.76 ± 0.52% and 99.12 ± 0.84, respectively, and relative standard deviation (RSD) of interday and intraday was less than 2%. The developed method was suitable and specific to the analysis of ETX even in the presence of common excipients. The method was applied on two different marketed brands and ETX contents were 98.5 ± 0.56 and 99.33 ± 0.44, respectively, of labeled claim. The proposed method was validated as per ICH guidelines and statistically good results were obtained. This method can be employed for routine analysis of ETX in bulk and commercial formulations. PMID:23378945

Singh, Shipra; Mishra, Amrita; Verma, Anurag; Ghosh, Ashoke K; Mishra, Arun K

2012-10-01

50

A simple Ultraviolet spectrophotometric method for the determination of etoricoxib in dosage formulations  

PubMed Central

The present study was undertaken to develop a validated, rapid, simple, and low-cost ultraviolet (UV) spectrophotometric method for estimating Etoricoxib (ETX) in pharmaceutical formulations. The analysis was performed on ? max 233 nm using 0.1 M HCl as blank/diluent. The proposed method was validated on International Conference on Harmonization (ICH) guidelines including parameters as linearity, accuracy, precision, reproducibility, and specificity. The proposed method was also used to access the content of the ETX in two commercial brands of Indian market. Beer's law was obeyed in concentration range of 0.1–0.5 ?g/ml, and the regression equation was Y = 0.418x + 0.018. The mean accuracy values for 0.1 ?g/ml and 0.2 ?g/ml concentration of ETX were found to be 99.76 ± 0.52% and 99.12 ± 0.84, respectively, and relative standard deviation (RSD) of interday and intraday was less than 2%. The developed method was suitable and specific to the analysis of ETX even in the presence of common excipients. The method was applied on two different marketed brands and ETX contents were 98.5 ± 0.56 and 99.33 ± 0.44, respectively, of labeled claim. The proposed method was validated as per ICH guidelines and statistically good results were obtained. This method can be employed for routine analysis of ETX in bulk and commercial formulations.

Singh, Shipra; Mishra, Amrita; Verma, Anurag; Ghosh, Ashoke K.; Mishra, Arun K.

2012-01-01

51

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

52

Development and Validation of a Spectrophotometric Method to Measure Sulfate Concentrations in Mine Water without Interference  

Microsoft Academic Search

Sulfate concentrations are determined in mine water by gravimetric, titrimetric, colorimetric, turbidometric, ion chromatographic,\\u000a inductively coupled plasma absorption spectrophotometric, and other methods. Accurate sulfate measurement of mine water can\\u000a be difficult due to interfering groups, cations, and anions, mainly arsenate (AsO4\\u000a 3?) and phosphate (PO4\\u000a 3?). In this paper, a simple and effective spectrophotometric method is described for the determination

Arup RoyBidus; Bidus Kanti Das; Jayanta Bhattacharya

53

[Spectrophotometric determination of boric acid by the curcumin method].  

PubMed

We have contrived an improved curcumin method for a spectrophotometric determination of the boric acid content, suitable for use on biologic materials to determine cases of poisoning. The use of this method enables detection of boric acid from a level of 10 micrograms/ml up to 5 mg/ml. The steps of this measurement method follow. Initially, boric acid was extracted by using a modification of Agazzi's method, i.e., to 1 ml of the sample solution, 0.2 ml of a 50% solution of sulfuric acid is added, along with 4 ml of 10 v/v% 2-ethyl-1,3-hexanediol/chloroform (an EHD solution). This mixture was then shaken for 5 min and then centrifuged for 10 min at 3,000 rpm. The extract of this chloroform phase was dehydrated with anhydrous sodium sulfate and used for the coloring reaction sample. The colorimetry procedure for determining the boric acid content follows. Fifty microliters of the extract solution was placed into a dry tube, to which 0.5 ml of a 0.3% curcumin/acetic acid solution and 50 microliters concentrated sulfuric acid were added, and the contents mixed thoroughly. The reaction mixture was then allowed to stand for 30 min at room temperature. (Rosocyanin is formed by the reaction of boric acid and protonated curcumin). Next, ethanol (3-138 ml) was added to the reaction mixture to decompose the excess protonated curcumin. Then, the absorbancy of the resulting solution was measured at 550 nm against a blank test solution. Ethanol was added to enable the measurement of the absorbancy (ethanol amounts tested were 3, 6, 12, 24, and 138 ml).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2636280

Yoshida, M; Watabiki, T; Ishida, N

1989-12-01

54

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

Microsoft Academic Search

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 4–400ngmL?1

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

2008-01-01

55

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

56

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

57

DETERMINATION OF GLYOXAL, METHYLGLYOXAL, AND DIACETYL IN SELECTED BEER AND WINE, BY HPLC WITH UV SPECTROPHOTOMETRIC DETECTION, AFTER DERIVATIZATION WITH o-PHENYLENEDIAMINE  

Microsoft Academic Search

The ?-diketones glyoxal, methylglyoxal, and diacetyl were determined in selected beer and wine using a procedure involving the use of C18 solid phase extraction columns to remove interferences and derivatization of the compounds with o-phenylenediamine to form quinoxalines, which are separated by HPLC and detected using UV spectrophotometric detection.Interferences were more difficult to remove in the case of beer, due

A. Barros; J. A. Rodrigues; P. J. Almeida; M. T. Oliva-Teles

1999-01-01

58

On-line UV spectrophotometric analysis for organic chemistry of novel inorganic polymer derived microreactor.  

PubMed

The use of microfluidic or lab-on-a-chip system has shown great promise for many applications. We have previously reported fabrication and application of preceramic polymer derived chemically and mechanically stable microfluidic devices in organic synthesis. Even though organic reactions are successfully performed, it is hard to analyze product to evaluate yields without any time delay except for integration of detecting module in the devices. Moreover small sample volume makes it even difficult to analyze sample by conventional analytical tools. Removal of catalyst and by product before analysis is another hurdle in evaluating performance of microrector. In this paper we describe preliminary results for simple on-line (real-time) quantitative analysis of microchemical reaction in preceramic polymer derived microreactor without reconstruction of microreactor or expensive components. A commercial UVNIS spectrophotometer is used to monitor well established Knoevenagel reaction. To evaluate the performance of presented on-line UV/IS monitoring system, UV/IS data are compared with off-line gas chromatography based analysis system. PMID:19908719

Cheon, Jin-Ho; Yoon, Tae-Ho; Hong, Lan-Young; Park, Sang-Hee; Kim, Dong-Pyo

2009-12-01

59

Spectrophotometric method for simultaneous estimation of atenolol in combination with losartan potassium and hydrochlorothiazide in bulk and tablet formulation  

PubMed Central

Aim: To develop a simple, accurate, rapid and precise UV spectrophotometric method for the estimation of atenolol in combination with losartan potassium and hydrochlorothiazide. Materials and Methods: The method employs formation and solving simultaneous equation using 251.60 nm and 224.20 nm for losartan potassium and atenolol, 224.20 and 271.60 for atenolol and hydrochlorothiazide as two analytical wavelengths, using methanol water as a solvent. Results and Conclusion: The linearity was observed in the concentration range of 5-30 µg/ml (r=0.9991) for losratan pottassium, 2 - 12 µg/ml (r = 0.9995) for atenolol and 2 - 14 µg/ml (r = 0.9993) for hydrochlorothiazide. The results of the method were validated statistically and by recovery studies.

Bari, Sanjay; Sathe, Shital; Jain, Pritam; Surana, Sanjay

2010-01-01

60

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

PubMed

Simple, sensitive and reliable derivative spectrophotometric methods were developed and validated for determination of alpha-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 at their wavelengths of determination were linear in the concentration range of alpha-tocopherol using peak to zero 10-250 microg ml(-1) for first and second derivative spectrophotometric methods. Developed spectrophotometric methods in this study are accurate, sensitive, precise, reproducible, and can be directly and easily applied to Evon dragee form as pharmaceutical preparation. Statistical analysis (Student's t-test) of the obtained results showed no significant difference between the proposed two methods. PMID:15337438

Yilmaz, Bilal; Oztürk, Murat; Kadio?lu, Yücel Ya?ar

2004-09-01

61

New sensitive kinetic spectrophotometric methods for determination of omeprazole in dosage forms.  

PubMed

New rapid, sensitive, and accurate kinetic spectrophotometric methods were developed, for the first time, to determine omeprazole (OMZ) in its dosage forms. The methods were based on the formation of charge-transfer complexes with both iodine and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). The variables that affected the reactions were carefully studied and optimized. The formed complexes and the site of interaction were examined by UV/VIS, IR, and (1)H-NMR techniques, and computational molecular modeling. Under optimum conditions, the stoichiometry of the reactions between OMZ and the acceptors was found to be 1 : 1. The order of the reactions and the specific rate constants were determined. The thermodynamics of the complexes were computed and the mechanism of the reactions was postulated. The initial rate and fixed time methods were utilized for the determination of OMZ concentrations. The linear ranges for the proposed methods were 0.10-3.00 and 0.50-25.00 mug mL(-1) with the lowest LOD of 0.03 and 0.14 mug mL(-1) for iodine and DDQ, respectively. Analytical performance of the methods was statistically validated; RSD was <1.25% for the precision and <1.95% for the accuracy. The proposed methods were successfully applied to the analysis of OMZ in its dosage forms; the recovery was 98.91-100.32% +/- 0.94-1.84, and was found to be comparable with that of reference method. PMID:20140076

Mahmoud, Ashraf M

2009-12-02

62

Refractive Index Determination of SIO2 Layer in the UV/VIS/NIR Range: Spectrophotometric Reverse Engineering on Single and Bi-Layer Designs  

NASA Astrophysics Data System (ADS)

In this paper we use spectrophotometric measurements and a Clustering Global Optimization procedure to determine the complex refractive index of SiO2 layer from 250 nm to 1250 nm. A special commercial optical module allows the reflection and transmission measurements to be made under exactly the same illumination and measurement conditions. We compare the index determination results obtained from two different single layer SiO2 samples, with high and low index glass substrates, respectively. We then determine the refractive index of SiO2 for a bi-layer design in which the first deposited layer is Ta2O5. The corresponding solutions are discussed and we show that the real part of the complex refractive index obtained for a bi-layer is slightly different to that found for a single layer investigation. When SiO2 is included inside a thin film stack, we propose the use of an index determination method in which a bi-layer is used for the real part of the complex refractive index, and single layer determination is used for the imaginary part of the refractive index in the UV range.

Gao, L.; Lemarchand, F.; Lequime, M.

2013-01-01

63

Derivative spectrophotometric method for determination of acidity constants of single step acid-base equilibria  

Microsoft Academic Search

A general derivative spectrophotometric method for determination of acidity constants is developed. The method appears suitable in cases when classical spectrophotometry cannot be employed due to little differences in the absorption spectra of conjugated acid-base pairs. Based on theoretical considerations, seven variants of the method have been established and their validity was checked, determining acidity constants of lorazepam and flurazepam

Gordana V Popovi?; Lidija B Pfendt; Violeta M Moskovljevi?

2001-01-01

64

Novel indirect spectrophotometric methods for determination of phosphate and arsenate using polyoxometalates and micellar medium  

Microsoft Academic Search

Five various methods based on the use of polyoxometalates (POMs) have been developed for indirect spectrophotometric determination of phosphate or arsenate. Amplification procedure involving formation of the 12-molybdophosphate, its extraction with butyl acetate, and stripping with ammonia differs from known method by applying sensitive reaction of molybdenum(VI) with phenylfluorone in presence of the nonionic surfactant neonole at the last step

A. B. Vishnikin

2005-01-01

65

Approach to the content of total extractable phenolic compounds from different food samples by comparison of chromatographic and spectrophotometric methods  

Microsoft Academic Search

A new approach to the error sources in the spectrophotometric determination of total phenols in foods has been performed. The choice of the suitable phenolic standard and the influence of sugars and proteins as interfering compounds were carefully studied. The results obtained by the spectrophotometric method were compared with those found from the chromatographic method which was taken as reference

A Escarpa; M. C González

2001-01-01

66

A new and sensitive method for the spectrophotometric determination of ethion in environmental and biological samples  

Microsoft Academic Search

A new and sensitive spectrophotometric method is described for the determination of sub ppm levels of the organophosphorus pesticide ethion based on the oxidation of ethion by potassium permanganate in phosphoric acid to sulphones and its hydrolysis under acidic condition at ~ 100°C to release formaldehyde, which is then determined by a reaction with 1,3,5-trihydroxybenzene (phloroglucinol) in alkaline medium. Beer's

Joyce Vanisha Das; V. K. Gupta

1995-01-01

67

Spectrophotometric and Reversed-Phase High-Performance Liquid Chromatographic Method for the Determination of Doxophylline in Pharmaceutical Formulations  

PubMed Central

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 C18 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.

Joshi, HR; Patel, AH; Captain, AD

2010-01-01

68

UV monitoring of sugars during wine making  

Microsoft Academic Search

A UV\\/UV system for the spectrophotometric determination of sugars during wine production is described. The methodology is based on the formation of a UV-absorbing byproduct produced by the photodegradation of sugars. Under the given experimental conditions, the influence of increasing the amount of acids and alcohol is negligible. The measurement by UV\\/UV is compared with FTIR as reference method and

B. Roig; O. Thomas

2003-01-01

69

Antioxidant capacity of bovine milk as assayed by spectrophotometric and amperometric methods  

Microsoft Academic Search

The total antioxidant capacity (TAC) of bovine milk, whey, and low-molecular-weight (LMW) fractions of whey was investigated using spectrophotometric methods including an ABTS-based method (reduction of the cation radical of 2,2?-azinobis(3-ethylenebenzothiazoline-6-sulfonic acid)) and a FRAP method (reduction of Fe3+). Significant antioxidant capacity in milk and whey was demonstrated by the ABTS method (TAC(ABTS)), and it apparently increased with increasing pH.

J Chen; H Lindmark-Månsson; L Gorton; B Åkesson

2003-01-01

70

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

71

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

72

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

73

Comparison of UV spectrophotometry and high performance liquid chromatography methods for the determination of repaglinide in tablets  

PubMed Central

Background: Repaglinide is a miglitinide class of antidiabetic drug used for the treatment of type 2 diabetes mellitus. A fast and reliable method for the determination of repaglinide was highly desirable to support formulation screening and quality control. Objective: UV spectrophotometric and reversed-phase high performance liquid chromatography (RP-HPLC) methods were developed for determination of repaglinide in the tablet dosage form. Materials and Methods: The UV spectrum recorded between 200 400 nm using methanol as solvent and the wavelength 241 nm was selected for the determination of repaglinide. RP-HPLC analysis was carried out using Agilent TC-C18 (2) column and mobile phase composed of methanol and water (80:20 v/v, pH adjusted to 3.5 with orthophosphoric acid) at a flow rate of 1.0 ml/min. Parameters such as linearity, precision, accuracy, recovery, specificity and ruggedness are studied as reported in the International Conference on Harmonization (ICH) guidelines. Results: The developed methods illustrated excellent linearity (r2 > 0.999) in the concentration range of 5-30 ?g/ml and 5-50 ?g/ml for UV spectrophotometric and HPLC methods, respectively. Precision (%R.S.D < 1.50) and mean recoveries were found in the range of 99.63-100.45% for UV spectrophotometric method and 99.71-100.25% for HPLC method which shows accuracy of the methods. Conclusion: The developed methods were found to be reliable, simple, fast, accurate and successfully used for the quality control of repaglinide as a bulk drug and in pharmaceutical formulations.

Dhole, Seema M.; Khedekar, Pramod B.; Amnerkar, Nikhil D.

2012-01-01

74

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

75

Spectrophotometric methods for the determination of lansoprazole and pantoprazole sodium sesquihydrate  

Microsoft Academic Search

Spectrophotometric procedures for determination of two irreversible proton pump inhibitors, lansoprazole (I) and pantoprazole sodium sesquihydrate (II) are presented. Two methods were based on charge transfer complexation reaction of these drugs, where they act as n-donors, with either ? acceptor 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and with ? acceptor as iodine. A third method was also investigated depending on ternary complex formation with

Azza A. M Moustafa

2000-01-01

76

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

Microsoft Academic Search

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

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

1986-01-01

77

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

NASA Astrophysics Data System (ADS)

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 25-40 min. The coloured condensation products are suitable for the spectrophotometric and spectrofluorimetric determination at 329-333 and 431-434 nm (excitation at 389 nm), respectively. For the spectrophotometric method, Beer's law was obeyed from 0.5 to 2.5 ?g ml -1 for tramadol, dothiepin and 5-25 ?g ml -1 for acebutolol. Using the spectrofluorimetric method linearity ranged from 0.25 to 1.25 ?g ml -1 for tramadol, dothiepin and 1-5 ?g ml -1 for acebutolol. Mean percentage recoveries for the spectrophotometric method were 99.68 ± 1.00, 99.95 ± 1.11 and 99.72 ± 1.01 for tramadol, acebutolol and dothiepin, respectively and for the spectrofluorimetric method, recoveries were 99.5 ± 0.844, 100.32 ± 0.969 and 99.82 ± 1.15 for the three drugs, respectively. The optimum experimental parameters for the reaction has been studied. The validity of the described procedures was assessed. Statistical analysis of the results has been carried out revealing high accuracy and good precision. The proposed methods were successfully applied for the determination of the selected drugs in their pharmaceutical preparations with good recoveries. The procedures were accurate, simple and suitable for quality control application.

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

2006-12-01

78

Kinetic-spectrophotometric method for the determination of trace amounts of bromide in seawater.  

PubMed

A novel simple, sensitive and rapid kinetic-spectrophotometric method is proposed for the determination of trace amounts of bromide. The method is based on its catalytic effect on the oxidation of methylene blue (MB) by hydrogen peroxide in strongly acidic solution. The oxidation reaction is activated by large amounts of chloride and can be monitored spectrophotometrically by measuring the decrease in the absorbance of MB at 746 nm. The determination of bromide is performed by a fixed-time method at the first 100 s from the initiation of the reaction. Unlike other kinetic-spectrophotometric methods for the determination of bromide, the proposed method does not require heating the solution. Bromide can be determined in the range from 80 to 960 microg l(-1) with the detection limit of 35 microg l(-1). The relative standard deviation of ten replicate determination of 480 microg l(-1) bromide was 1.4%. The influence of potential interfering ions was studied. The proposed method was satisfactorily applied to the determination of bromide in seawater without interfering effect from chloride ion. PMID:18970415

Uraisin, Kanchana; Takayanagi, Toshio; Oshima, Mitsuko; Nacapricha, Duangjai; Motomizu, Shoji

2005-08-11

79

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

80

Spectrophotometric method for the determination of nifedipine with 4-(methylamino)phenol and potassium dichromate  

Microsoft Academic Search

A new simple, sensitive and reproducible spectrophotometric method for the determination of nifedipine in pure and dosage forms has been proposed. It is based on the reduction of nifedipine with Zn\\/NH4Cl, followed by coupling with N-methyl-1,4-benzoquinoneimine—the oxidation product of 4-(methylamino)phenol, to give a chromophore which absorbed maximally at 525 nm. The experimental conditions were optimised and Beer's law was obeyed

Nafisur Rahman

2002-01-01

81

Crucial problem in rapid spectrophotometric determination of 2,4,6-trinitrotoluene and its breakthrough method.  

PubMed

A rapid spectrophotometric determination for 2,4,6-trinitrotoluene (TNT) is significant because this method is suitable for simultaneous analyses of the numerous samples. We found one problem that TNT reduction products interfere with the TNT detection in this assay, and we overcame this problem by heating the samples at 95 degrees C, resulting in the production of compounds that did not interfere. PMID:16545473

Maeda, Toshinari; Kubota, Akira; Nagafuchi, Nobuaki; Kadokami, Kiwao; Ogawa, Hiroaki I

2006-03-06

82

Limitations of commonly used spectrophotometric assay methods for phosphoenolypyruvate carboxykinase activity in crude extracts of muscle.  

PubMed Central

Phosphoenolpyruvate carboxykinase activity in crude extracts of muscle has frequently been determined by using a continuous spectrophotometric method, which is shown to grossly overestimate enzyme activity. NADH oxidation attributed to phosphoenolpyruvate carboxykinase activity in the assay is due to lactate production. Under the normal assay conditions. Na+ ions stimulate pyruvate kinase, providing pyruvate for lactate formation by lactate dehydrogenase and sufficiently to account for most of the observed NADH oxidation.

Duff, D A; Snell, K

1982-01-01

83

A spectrophotometric method for determination of solid fat content of palm oil  

Microsoft Academic Search

A new spectrophotometric method has been developed for determining solid fat content (SFC) of crude palm oil based on the\\u000a different solubilities of the inherent carotenes in the solid and liquid components of the oil. The sample to be analyzed\\u000a is tempered according to usual procedures and then either filtered or centrifuged to liberate the liquid component (olein).\\u000a The carotene

A. S. H. Ong; P. L. Boey; C. M. Ng

1982-01-01

84

Spectrophotometric method for the determination of 1,2-propylene glycol  

Microsoft Academic Search

A spectrophotometric method is proposed for the determination of 1,2-propylene glycol. It is based on the ADH\\/ AlDH catalyzed\\u000a oxidation of propylene glycol by NAD+. The NADH formed is measured at 340 nm. Alcohol dehydrogenase from equine liver was found to be much more effective than\\u000a that of yeast. No enantiomeric selectivity for s(+) propylene glycol was observed. A linear

T. Machate; A. Kettrup

1998-01-01

85

A Spectrophotometric Method for the Determination of Buclizine Hydrochloride Using the Charge-Transfer Spectrum of Buclizine-Iodine Complex  

Microsoft Academic Search

A simple and sensitive spectrophotometric method is described for the determination of buclizine hydrochloride in bulk and tablets form. The method is based on the formation of charge-transfer complex between buclizine, as n-donor, and iodine, as ? acceptor, which measured spectrophotometrically at 295 and 355 nm. A Job's plot indicated a 1:1 complex between the drug and iodine and Beer's

Abdel Fattah M. El Walily; Alaa El Gindy; Abdel Aziz M. Wahbi

1996-01-01

86

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

2013-07-02

87

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

NASA Astrophysics Data System (ADS)

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 ?g L-1, with sensitivity enhancement factor of 23. The relative standard deviation (RSD) for seven replicate measurements of 50 ?g L-1 of cobalt was 4.3%. The recoveries for the spiked samples were in the acceptable range of 93.8-105%.

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

2013-11-01

88

Spectrophotometric Method for Simultaneous Estimation of Escitalopram Oxalate and Clonazepam in Tablet Dosage Form  

PubMed Central

A simple, accurate and precise spectrophotometric method has been developed for simultaneous estimation of escitalopram oxalate and clonazepam in combined dosage form. Simultaneous equation method is employed for simultaneous determination of escitalopram oxalate and clonazepam from combined dosage forms. In this method, the absorbance was measured at 238 nm for escitalopram oxalate and 273 nm for clonazepam. Linearity was observed in range of 5-100 ?g/ml and 5-50 ?g/ml for escitalopram and clonazepam respectively. Recovery studies confirmed the accuracy of proposed method and results were validated as per ICH guidelines. The method can be used for routine quality control of pharmaceutical formulation containing escitalopram and clonazepam.

Kakde, R. B.; Satone, D. D.

2009-01-01

89

A Rapid and Specific Spectrophotometric Method for Determining Propoxyphene.  

National Technical Information Service (NTIS)

A rapid method for the quantitative determination of propoxyphene in biological materials is presented. The method involves formation of a steam distillable product which has a molar absorbancy for ultraviolet light many times greater than that of propoxy...

J. E. Wallace J. D. Biggs E. V. Dahl

1965-01-01

90

Isomeric Transformation Of 4Aminobiphenyl by U.V. Radiation and its Influence on the Determination by Flow Injection Analysis with Amperometric and Spectrophotometric Detection  

Microsoft Academic Search

Two flow-injection methods for the determination of 4-aminobiphenyl by amperometry (glassy carbon electrode) and spectrophotometry are proposed. A sample volume of 200 or 400 ?l containing an analyte concentration of 0.1–1.0 ?g ml or 0.8–24.0 ?g ml for amperometric or spectrophotometric detection, respectively, is injected into a carrier stream containing 0.04 or 0.02 M Britton-Robinson buffer at pH 10.0 or

M. H. Blanco; M. C. Quintana; P. Hernández; J. Vicente; L. Hernández

1995-01-01

91

Spectrophotometric assessment of salivary ?-galactosidases in halitosis.  

PubMed

The aim of this work was to develop a spectrophotometric method for the measurement of salivary ?-galactosidase for the evaluation of oral malodor. A comparison between different methods for estimating oral malodor has been conducted on 94 healthy adult volunteers. For organoleptic measurements, the subjects were instructed to exhale briefly through the mouth at a distance of approximately 10 cm from the noses of two trained judges. The evaluation of ?-galactosidase activity was accomplished in unstimulated whole saliva of all participants through the colorimetric method and spectrophotometry. A significant association among spectrophotometric evaluation of ?-galactosidase and organoleptic measurements was assessed by Spearman correlations. Although colorimetric and spectrophotometric assessments of ?-galactosidases were estimated to have the same sensitivity, the last method is characterized by a higher specificity. The results suggest that the use of the UV-vis spectrophotometer increases the specificity of the evaluation of salivary ?-galactosidases. PMID:22427486

Petrini, M; Trentini, P; Ferrante, M; D'Alessandro, L; Spoto, G

2012-03-19

92

Simultaneous determination of retinoic acid and hydroquinone in skin ointment using spectrophotometric technique (ratio difference method)  

PubMed Central

An innovative spectrophotometric method was developed for simultaneous determination of compounds with interfering spectra in binary mixtures without previous separation, showing significant advantages over the conventional methods regarding minimal data manipulation and applicability. The proposed method was applied for the determination of retinoic acid and hydroquinone in laboratory-prepared mixtures with mean percentage recoveries 100.13 ± 0.31 and 99.99 ± 0.04, respectively, and in their pharmaceutical formulation with mean percentage recoveries 100.13 ± 0.86 and 100.07 ± 0.58, respectively. The method was validated according to USP guidelines and can be applied for routine quality control testing.

Elzanfaly, Eman S.; Saad, Ahmed S.; Abd-Elaleem, Abd-Elaziz B.

2012-01-01

93

Simultaneous determination of imipramine hydrochloride and chlordiazepoxide in pharmaceutical preparations by spectrophotometric, RP-HPLC, and HPTLC methods.  

PubMed

A binary mixture of imipramine HCl and chlordiazepoxide was determined by three different methods. The first involved determination of imipramine HCl and chlordiazepoxide using the first derivative spectrophotometric technique at 219 and 231.5 nm over the concentration ranges of 1-20 and 2-24 microg/mL with mean accuracies of 99.47 +/- 0.78 and 101.43 +/- 1.20%, respectively. The second method utilized RP-HPLC with methanol-acetonitrile-0.065 M ammonium acetate buffer (45 + 25 + 30, v/v/v, pH adjusted to 5.6 +/- 0.02 with phosphoric acid) as the mobile phase pumped at a flow rate of 1.0 mL/min. Quantification was achieved using UV detection at 240 nm over concentration ranges of 0.25-4.0 and 0.1-1.6 microg/mL, with mean accuracies of 101.17 +/- 0.56 and 100.67 +/- 0.40% for imipramine HCl and chlordiazepoxide, respectively. The third method was HPTLC with carbon tetrachloride-acetone-triethylamine (pH 8.3; 6 + 3 + 0.3, v/v/v) as the mobile phase. Quantification was achieved with UV detection at 240 nm over concentration ranges of 50-600 and 20-240 ng/spot with mean accuracies of 99.51 +/- 0.59 and 100.59 +/- 0.84% for imipramine HCl and chlordiazepoxide, respectively. The suggested procedures were checked using prepared mixtures, and were successfully applied for the analysis of pharmaceutical preparations. The accuracy and precision of the methods were confirmed when the standard addition technique was applied. The results obtained by applying the proposed methods were statistically analyzed. PMID:20629393

Patel, Sejal K; Patel, Natvarlal J

94

Spectrophotometric screening method for acetaminophen in serum and plasma.  

PubMed

We describe a simple, economical procedure for rapidly detecting acetaminophen in serum or plasma. The method is based upon the reduction by the drug of ferric 2,4,6-tris(2-pyridyl)-s-triazine, at an acidic pH, to ferrous 2,4,6-tris(2-pyridyl)-S-triazine complex, which absorbs maximally at 593 nm. Absorbance and acetaminophen concentration are linearly related from 25 to 400 mg/L, and so therapeutic and toxic concentrations can be measured. The method is accurate; day-to-day CV's for two pooled control specimens (103 and 227 mg/L) were 4.4 and 6.6%. Correlation studies, with an established nitration method and with the free-radical diphenylpicrylhydrazyl dye method, showed correlation coefficients of 0.985 and 0.915, respectively. Of 25 commonly used drugs tested, only levodopa, oxyphenylbutazone, and phenylephrine interfere significantly. Interference from salicylate, salicylamide, and phenylbutazone was insignificant. PMID:7356576

Liu, T Z; Oka, K H

1980-01-01

95

Bacterial Monitoring in Vials Using a Spectrophotometric Assimilation Method  

Microsoft Academic Search

Aseptic-filling processes are often used with fragile parenteral products that might be destroyed by terminal autoclaving. However, aseptic filling is not as effective as autoclaving in reducing contamination. As a result, time-consuming microbiological methods and turbidimetry are employed currently as product inspection techniques, but these processes can destroy the product and might not detect low levels of contamination. Thus, near-infrared

Leonard J. Galante; Michael A. Brinkley; Robert A. Lodder

1992-01-01

96

Conjugated autoxidizable triene (CAT) assay: a novel spectrophotometric method for determination of antioxidant capacity using triacylglycerol as ultraviolet probe.  

PubMed

Described here is a novel spectrophotometric method for estimating antioxidant capacity in a 96-well microplate using as UV probes the conjugated triene triacylglycerols (TAGs) naturally present in tung oil. The TAGs of this commercially available oil contain around 86% eleostearic acid, an octadecatrienoic acid with conjugated trienes exhibiting strong UV absorption at 273 nm. In an oil-in-water emulsion at 37 degrees C, the azo initiator 2,2'-azobis(2-amidinopropane) dihydrochloride generated a constant flux of peroxy radicals, which destroyed the conjugated trienes. The absorbance decay at 273 nm, related to oxidative degradation of conjugated triene TAGs, was monitored in the absence and presence of various concentrations of antioxidants. To validate this new method, the antioxidant capacity of four phenolic compounds (gallic acid, (-)-epicatechin, chlorogenic acid, and rosmarinic acid) was measured using an area-under-the-curve calculation and expressed as Trolox equivalents, the value for Trolox being taken as reference. The order of efficacy was found to be rosmarinic acid > chlorogenic acid approximately epicatechin>Trolox>gallic acid, which can be partially explained by the number of catecholic moieties and the polarity of these antioxidants. Moreover, the conjugated autoxidizable triene (CAT) assay provided good insight into antioxidant behavior (i.e., retarder or chain breaker). The same molecules were then analyzed in 2,2-diphenyl-1-picrylhydrazyl and fluorescein-based oxygen radical absorbance capacity assays, and the results are discussed critically with respect to those obtained with the CAT assay. This new method may constitute an easy-to-use, sensitive, and high-throughput in vitro protocol for evaluation of the antioxidant capacity of pure molecules and natural extracts in lipid oxidation. PMID:18585362

Laguerre, Mickaël; López-Giraldo, Luis J; Lecomte, Jérôme; Baréa, Bruno; Cambon, Emmanuelle; Tchobo, Paul Fidèle; Barouh, Nathalie; Villeneuve, Pierre

2008-06-10

97

A new microlens array fabrication method using UV proximity printing  

Microsoft Academic Search

This paper presents a new microlens array fabrication method that controls the printing gap in the UV lithography process. This method can precisely control the microlens array geometric profile array in the fabrication process without thermal reflow. The proximity printing bends the UV light away from the aperture edges and produces a certain exposure in the photoresist outside the aperture

Lin Che-Ping; Yang Hsiharng; Chao Ching-Kong

2003-01-01

98

Alternative curing methods of UV curable automotive clearcoats  

Microsoft Academic Search

Alternative methods for curing UV curable clearcoats were characterized using confocal Raman microscopy, nano-scratch measurements, and dynamic mechanical thermal analysis (DMTA). Clearcoats were cured using a xenon flash lamp, fluorescent UV bulbs with various spectral power distributions, and a microwave powered lamp. Raman spectroscopy was used to track acrylate double bond conversion of the clearcoat after each method of curing.

C. M. Seubert; M. E. Nichols

2004-01-01

99

A novel spectrophotometric method for determination of kinetic constants of aldehyde oxidase using multivariate calibration method.  

PubMed

Although phenanthridine has been frequently used as a specific substrate for the assessment of aldehyde oxidase activity, the use of this method is questionable due to a lower limit of detection and its validity for kinetic studies. In the present study, a novel sensitive multivariate calibration method based on partial least squares (PLS) has been developed for the measurement of aldehyde oxidase activity using phenanthridine as a substrate. Phenanthridine and phenanthridinone binary mixtures were prepared in a dynamic linear range of 0.1-30.0 microM and the absorption spectra of the solutions were recorded in the range of 210-280 nm in Sorenson's phosphate buffer (pH 7.0) containing EDTA (0.1 mM). The optimized PLS calibration model was used to calculate the concentration of each chemical in the prediction set. Hepatic rat aldehyde oxidase was partially purified and the initial oxidation rates of different concentrations of phenanthridine were calculated using the PLS method. The values were used for calculating Michaelis-Menten constants from a Lineweaver-Burk double reciprocal plot of initial velocity against the substrate concentration. The limits of detection for phenanthridine and phenanthridinone were found to be 0.04+/-0.01 and 0.03+/-0.01 microM (mean+/-SD, n=5), respectively. Using this method, the Km value for the oxidation of phenanthridine was calculated as 1.72+/-0.09 microM (mean+/-SD, n=3). Thus, this study describes a novel spectrophotometric method that provides a suitable, sensitive and easily applicable means of measuring the kinetics of phenanthridine oxidation by aldehyde oxidase without the need for expensive instrumentation. PMID:17936364

Sorouraddin, Mohammad-Hossein; Fooladi, Ebrahim; Naseri, Abdolhossein; Rashidi, Mohammad-Reza

2007-09-18

100

Spectrophotometric method for quantitative determination of montelukast in bulk, pharmaceutical formulations and human serum  

Microsoft Academic Search

A simple ultraviolet spectrophotometric method for the estimation of montelukast in methanol has been devised and been compared\\u000a with the existing pharmacopoeial RP-HPLC method for estimation of the drug. The limit of detection of montelukast at 283 nm\\u000a was 75.2 ng\\/mL. The calibration was linear in the range of 3–45 ?g\\/mL. Analytical parameters such as stability, selectivity,\\u000a accuracy and precision

M. Saeed Arayne; Najma Sultana; Fida Hussain

2009-01-01

101

A spectrophotometric method to precisely determine endpoint titers in complement fixation assays.  

PubMed

Since the early 20th century, complement fixation (CF) testing has been used to quantify the humoral response to various pathogens. The qualification of a positive result is based on a subjective determination of 30% lysis of sheep red blood cells, which can lead to variability in the analysis. A spectrophotometric reading of a standard with a known 30% lysis was used to standardize the currently used CF method and tested with controls and patient sera for various fungal assays. By utilizing this method a precise and non-subjective determination of endpoint titers was achieved. PMID:22628235

Welch, Ryan J; Merrigan, Stephen D; Delgado, Julio C

2012-05-01

102

Zero Order Spectrophotometric Method for Estimation of Escitalopram Oxalate in Tablet Formulations  

PubMed Central

A new, simple, fast and reliable zero order spectrophotometric method has been developed for determination of Escitalopram Oxalate in bulk and tablet dosage forms. The quantitative determination of drug was carried out using the zero order values (absorbance) measured at 238 nm. Calibration graph constructed at 238 nm was linear in concentration range of 2-20 µg/ml with correlation coefficient 0.9999. The method was found to be precise, accurate, specific, and validated as per ICH guidelines and can be used for determination of Escitalopram Oxalate in tablet formulations.

Sharma, S; Rajpurohit, H; Sonwal, C; Bhandari, A; Choudhary, VR; Jain, T

2010-01-01

103

Sensitive spectrophotometric methods for the assessment of nitrite in water sample  

Microsoft Academic Search

Two spectrophotometric methods have been developed for the determination of nitrite using dapsone (DAP) with ?-naphthol and\\u000a 4-amino-5-hydroxynapthalene-2,7-disulphonic acid monosodium salt (AHNDMS) as chromogenic reagents with maximum absorbance\\u000a wavelength at 540 and 520 nm respectively. For the method that utilizes dapsone with ?-naphthol (DAP-?-naphthol), the beer’s\\u000a law range is obeyed between 0.05–0.8 ?g ml?1 with molar absorptivity of 5.749?×?104 l mol?1 cm?1. The

P. Nagaraj; J. S. Prakash; Anantharaman Shivakumar; Ashwinee Kumar Shrestha

2008-01-01

104

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

105

Field determination of trace iron in fresh water samples by visual and spectrophotometric methods.  

PubMed

Sensitive visual and micro spectrophotometric methods have been developed for field determination of trace iron in fresh water samples. For the visual method, a water sample (0.45-microm filtrate acidified to 0.1 M HCl) was placed in a glass vial and mixed with a reagent solution containing 1,10-phenanthroline, sodium thiocyanate and 0.1 M HCl. Iron was extracted as pink ferroin thiocyanate with 1 ml of 4-methy-2-pentanone. The sample up to 20 ml was added step-by-step, until the color of the extract was detected visually. Without any special instrument or color standard, iron down to 0.001 mg 1(-1) (0.025 microg) in a sample can be determined with an error of 20% in the field. For the micro spectrophotometric method, the extract for 20 ml of sample was separated by capillary suction in a column (micro pipette chip) with acrylic fibers. A part of the extract was pushed out into a micro cell for the absorbance measurement at 525 nm. The column was re-usable after washing with ethanol. This method had a detection limit of 0.001 mg 1(-1) and allowed determinations within an error of 5%. The proposed methods were applied to deionized-, tap-, river-, lake- and reservoir-water samples. PMID:15352504

Kawakubo, Susumu; Naito, Ayako; Fujihara, Asuka; Iwatsuki, Masaki

2004-08-01

106

Optimization of a direct spectrophotometric method to investigate the kinetics and inhibition of sialidases  

PubMed Central

Backgrounds Streptococcus pneumoniae expresses three distinct sialidases, NanA, NanB, and NanC, that are believed to be key virulence factors and thus, potential important drug targets. We previously reported that the three enzymes release different products from sialosides, but could share a common catalytic mechanism before the final step of product formation. However, the kinetic investigations of the three sialidases have not been systematically done thus far, due to the lack of an easy and steady measurement of sialidase reaction rate. Results In this work, we present further kinetic characterization of pneumococcal sialidases by using a direct spectrophotometric method with the chromogenic substrate p-nitrophenyl-N-acetylneuraminic acid (p-NP-Neu5Ac). Using our assay, the measured kinetic parameters of the three purified pneumococcal sialidase, NanA, NanB and NanC, were obtained and were in perfect agreement with the previously published data. The major advantage of this alternative method resides in the direct measurement of the released product, allowing to readily determine of initial reaction rates and record complete hydrolysis time courses. Conclusion We developed an accurate, fast and sensitive spectrophotometric method to investigate the kinetics of sialidase-catalyzed reactions. This fast, sensitive, inexpensive and accurate method could benefit the study of the kinetics and inhibition of sialidases in general.

2012-01-01

107

[Nonlinear partial least squares method for simultaneous derivative spectrophotometric determination of two components in compound sulfamethoxazole].  

PubMed

A nonlinear model of consistency with derivative absorption in multiple components systems has been given. Model data were estimated by partial least squares method. A method for the simultaneous derivative spectrophotometric determination of two components with nonlinear partial least squares method was established. The method has been applied to the simultaneous determination of two components in compound sulfamethoxazole tablets. The average recoveries of sulfamethoxazole and trimethoprim in synthetic samples were 99.8% and 100.1%, and relative standard deviations were 1.3% and 1.6%, respectively. The results by nonlinear PLS method are significantly better than those by linear PLS method. The results for actual compound formulation agreed with those obtained by standard method. PMID:15769062

Zhou, Tong; Zhong, Jia-yue; Feng, Jiang

2004-05-01

108

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.

Abdellaziz, Lobna M.; Hosny, Mervat M.

2011-01-01

109

Spectrophotometric Methods for the Determination of Linagliptin in Binary Mixture with Metformin Hydrochloride and Simultaneous Determination of Linagliptin and Metformin Hydrochloride using High Performance Liquid Chromatography  

PubMed Central

Simple, accurate and precise Zero order, first derivative spectrophotometric and chromatographic methods have been developed and validated for the determination of linagliptin (LNG) and metformin HCl (MET). The zero order and first derivative spectrophotometric methods were used for the determination of LNG in the range of 5-30 ?g mL?1 by measuring the absorbance at 299 nm and 311 respectively. Besides, a reversed-phase liquid chromatographic (RP-LC) method is described for the simultaneous determination of LNG and MET. Chromatographic separation was achieved on a Symmetry® Waters C18 column (150 mm × 4.6 mm, 5 ?m). Isocratic elution based on potassium dihydrogen phosphate buffer pH (4.6) - methanol (30:70, v/v) at a flow rate of 1 mLmin?1 with UV detection at 260 nm was performed. Linearity, accuracy and precision were found to be acceptable over the concentration ranges of 0.125-4 ?g mL?1 and 20-800 ?g mL?1 for LNG and MET, respectively. The results were statistically compared using one-way analysis of variance (ANOVA). The optimized methods were validated and proved to be specific, robust, precise and accurate for the quality control of the drugs in their pharmaceutical preparation.

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

2013-01-01

110

Three different spectrophotometric methods manipulating ratio spectra for determination of binary mixture of Amlodipine and Atorvastatin  

NASA Astrophysics Data System (ADS)

Three simple, specific, accurate and precise spectrophotometric methods manipulating ratio spectra are developed for the simultaneous determination of Amlodipine besylate (AM) and Atorvastatin calcium (AT) in tablet dosage forms. The first method is first derivative of the ratio spectra ( 1DD), the second is ratio subtraction and the third is the method of mean centering of ratio spectra. The calibration curve is linear over the concentration range of 3-40 and 8-32 ?g/ml for AM and AT, respectively. These methods are tested by analyzing synthetic mixtures of the above drugs and they are applied to commercial pharmaceutical preparation of the subjected drugs. Standard deviation is <1.5 in the assay of raw materials and tablets. Methods are validated as per ICH guidelines and accuracy, precision, repeatability and robustness are found to be within the acceptable limit.

Darwish, Hany W.; Hassan, Said A.; Salem, Maissa Y.; El-Zeiny, Badr A.

2011-12-01

111

Three different spectrophotometric methods manipulating ratio spectra for determination of binary mixture of Amlodipine and Atorvastatin.  

PubMed

Three simple, specific, accurate and precise spectrophotometric methods manipulating ratio spectra are developed for the simultaneous determination of Amlodipine besylate (AM) and Atorvastatin calcium (AT) in tablet dosage forms. The first method is first derivative of the ratio spectra ((1)DD), the second is ratio subtraction and the third is the method of mean centering of ratio spectra. The calibration curve is linear over the concentration range of 3-40 and 8-32 ?g/ml for AM and AT, respectively. These methods are tested by analyzing synthetic mixtures of the above drugs and they are applied to commercial pharmaceutical preparation of the subjected drugs. Standard deviation is <1.5 in the assay of raw materials and tablets. Methods are validated as per ICH guidelines and accuracy, precision, repeatability and robustness are found to be within the acceptable limit. PMID:21908232

Darwish, Hany W; Hassan, Said A; Salem, Maissa Y; El-Zeiny, Badr A

2011-08-12

112

DEVELOPMENT AND STATISTICAL VAIDATION OF SPECTROPHOTOMETRIC METHOD FOR THE ESTIMATION OF MOSAPRIDE IN PHARMACEUTICAL FORMULATION  

Microsoft Academic Search

Three simple, precise and economical UV methods have been developed for the estimation of Mosapride in bulk and pharmaceutical formulations. Mosapride has the absorbance maxima at 309nm (Method A), and in the first order derivative spectra, showed zero crossing at 309 nm, with a sharp peak at 300 nm when n=1 (Method B), Method C applied was Area Under Curve

113

Validated spectrophotometric methods for the simultaneous determination of ciprofloxacin hydrochloride and metronidazole in tablets.  

PubMed

A binary mixture of ciprofloxacin hydrochloride (CIP) and metronidazole (MET) was determined by five simple and accurate methods, without prior separation. In the first method, CIP was determined by second derivative spectrophotometric method ((2)D) by measuring the amplitude at 282 nm (zero ordinate value of MET). On the other hand, the determination of MET was based on isosbestic point technique, where the total content of the mixture was determined at 294.5 nm (isosbestic point), then the content of MET could be calculated by subtraction. The second method was first derivative ratio spectrophotometric method ((1)DD) where the total amplitude at 261 and 285 nm and the amplitude at 295.5 nm were selected to simultaneously determine CIP and MET in binary mixture, respectively. The third method was based on dual wavelength analysis, in which two wavelengths were selected, at which the absorbances of the other component were the same. The fourth method depends on using Q-analysis method (absorbance ratio) which involves the formation of Q-absorbance equation using the respective absorptivity values at 294.5 nm (isosbestic point) and 281.5 nm (?(max) of CIP). The fifth method is partial least-squares (PLS) chemometric technique for determination of CIP and MET. The developed methods were successfully applied to the analysis of CIP and MET in laboratory prepared mixtures and tablets with good recoveries and their validation was carried out following the International Conference on Harmonization (ICH) guidelines. The results obtained were statistically compared with each other showing no significant difference with respect to accuracy and precision. PMID:22130371

Mahrouse, Marianne Alphonse; Elkady, Ehab Farouk

2011-01-01

114

A nanosilver-based spectrophotometric method for determination of malachite green in surface water samples.  

PubMed

A new spectrophotometric method is reported for the determination of nanomolar level of malachite green in surface water samples. The method is based on the catalytic effect of silver nanoparticles on the oxidation of malachite green by hexacyanoferrate (III) in acetate-acetic acid medium. The absorbance is measured at 610 nm with the fixed-time method. Under the optimum conditions, the linear range was 8.0?×?10(-9)-2.0?×?10(-7)?mol?L(-1) malachite green with a correlation coefficient of 0.996. The limit of detection (S/N?=?3) was 2.0?×?10(-9)?mol?L(-1). Relative standard deviation for ten replicate determinations of 1.0?×?10(-8)?mol?L(-1) malachite green was 1.86%. The method is featured with good accuracy and reproducibility for malachite green determination in surface water samples without any pre-concentration and separation step. PMID:23203820

Sahraei, R; Farmany, A; Mortazavi, S S; Noorizadeh, H

2012-12-01

115

Quantitative analysis of clopidogrel bisulphate and aspirin by first derivative spectrophotometric method in tablets.  

PubMed

A simple, accurate and precise spectrophotometric method has been developed for simultaneous estimation of clopidogrel bisulphate and aspirin by employing first order derivative zero crossing method. The first order derivative absorption at 232.5 nm (zero cross point of aspirin) was used for clopidogrel bisulphate and 211.3 nm (zero cross point of clopidogrel bisulphate) for aspirin.Both the drugs obeyed linearity in the concentration range of 5.0 ?g/ml to 25.0 ?g/ml (correlation coefficient r(2)<1). No interference was found between both determined constituents and those of matrix. The method was validated statistically and recovery studies were carried out to confirm the accuracy of the method. PMID:21969765

Game, Madhuri D; Gabhane, K B; Sakarkar, D M

2010-11-01

116

Quantitative Analysis of Clopidogrel Bisulphate and Aspirin by First Derivative Spectrophotometric Method in Tablets  

PubMed Central

A simple, accurate and precise spectrophotometric method has been developed for simultaneous estimation of clopidogrel bisulphate and aspirin by employing first order derivative zero crossing method. The first order derivative absorption at 232.5 nm (zero cross point of aspirin) was used for clopidogrel bisulphate and 211.3 nm (zero cross point of clopidogrel bisulphate) for aspirin.Both the drugs obeyed linearity in the concentration range of 5.0 ?g/ml to 25.0 ?g/ml (correlation coefficient r2<1). No interference was found between both determined constituents and those of matrix. The method was validated statistically and recovery studies were carried out to confirm the accuracy of the method.

Game, Madhuri D.; Gabhane, K. B.; Sakarkar, D. M.

2010-01-01

117

Determination of ametryn in sugarcane and ametryn-atrazine herbicide formulations using spectrophotometric method.  

PubMed

A sensitive spectrophotometric method has been developed for determination of ametryn in agricultural samples. The proposed method was based on reaction with pyridine and further coupling with sulfanilic acid to form a colored product. The absorbance was measured at 400 nm with a molar absorptivity of 2.1 x 10(5) L mol(-1) cm(-1). The method shows a linear range from 0.2-20 ?g mL(-1) with limit of detection and limit of quantification 0.16 and 0.54 ?g mL(-1), respectively. The method has been successfully applied to the determination of ametryn in sugarcane juice and commercial formulations after separation of ametryn from triazine herbicides based on solvent extraction. Recovery values were found to be in the range of 96.0 ± 0.2% to 98.4? ± ?0.1%. PMID:21713463

Shah, Jasmin; Jan, M Rasul; Ara, Behisht; Shehzad, Farhat-Un-Nisa

2011-06-29

118

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

2013-03-07

119

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

120

Influence of uranyldibutyl phosphate on the uv/vis spectrophotometric online monitoring of uranium in tributylphosphate/hydrocarbon solvent  

SciTech Connect

Evidence has been presented based on chemical analysis, Infrared, NMR, and uv/vis spectroscopy to support a structure of UO/sub 2/(DBP)/sub 2/ for uranyl dibutyl phosphate complex. Further, that absorbance measurement based on uranyl tributyl phosphate standards can be in error when uranyl dibutyl phosphate is present. Also, due to the limited solubility of the UO/sub 2/(DBP)/sub 2/ at low pH, the complex can precipitate and contribute to emulsions.

Creech, E.T.; Rutenberg, A.C.; Smithwick, R.W. III; Seals, R.D.

1984-03-30

121

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

122

Direct and selective spectrophotometric method for the determination of vanadium in steel, environmental and biological samples.  

PubMed

A simple, direct and selective spectrophotometric method for determination of vanadium is described. The present methodology is based on the strong oxidizing power of vanadium (V). Vanadium (V) selectively oxidizes leucocrystal violet (LCV) to crystal violet in the presence of phosphoric acid. The violet colored dye obtained shows maximum absorbance at 590 nm. Beer's law is obeyed in the concentration range 0.06-0.6 ?g ml(-1). The molar absorptivity and Sandell's sensitivity are found to be 6.78×10(4) l mol(-1) cm(-1) and 0.0044 ?g cm(-2), respectively. The proposed method is simple, direct, and sensitive. It has been successfully applied for the determination of vanadium in various environmental, biological and steel samples. PMID:21764362

Mathew, Sunitha B; Pataila, Girija; Pillai, Ajai K; Gupta, V K

2011-06-15

123

A facile spectrophotometric method for cobalt determination using alpha-benzilmonoxime in sodium dodecylsulfate micellar solutions.  

PubMed

Alpha-benzilmonoxime in sodium dodecylsulfate micellar media has been used for the spectrophotometric determination of cobalt at pH 9.0. The linear range of calibration is 0.05-1.50 microg cm(-3) of cobalt at 380 nm with molar absorptivity of 3.72 x 10(4) dm3 mol(-1) cm(-1), which is about 1.5-times greater than that of the alpha-benzilmonoxime extraction based method. The relative standard deviations, recoveries, detection limit and effects of diverse ions on the determination of cobalt were studied. These analytical results were satisfactory. The method was successfully applied to the determination of cobalt in the various samples. PMID:14640457

Eskandari, Habibollah; Karkaragh, Gholam Hassan Imanzadeh

2003-11-01

124

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.

Ilango, Kaliappan; Kumar, Pushpangadhan S. Shiji

2012-01-01

125

Derivative and Q-analysis Spectrophotometric Methods for Estimation of Hydrochlorothiazide and Olmesartan Medoxomil in Tablets.  

PubMed

Two methods for simultaneous estimation of hydrochlorothiazide and olmesartan medoxomil in combined tablet dosage form have been developed. The first method is the application of Q-analysis method (absorbance ratio), which involves the formation of Q-absorbance equation at 264 nm (isobestic point) and at 271 nm, the maximum absorption of hydrochlorothiazide. The linearity ranges for hydrochlorothiazide and olmesartan medoxomil were 2.5-22.5 mug/ml and 4-36 mug/ml, respectively. The second method is based on the derivative spectrophotometric method at zero crossing wavelengths. The linearity ranges for hydrochlorothiazide and olmesartan medoxomil were 2.5-20 mug/ml and 4-32 mug/ml, respectively. The accuracy of the methods were assessed by recovery studies and was found to be 100.45% +/-0.4215 and 100.24% +/-0.3783 for absorbance ratio method and 99.39% +/-0.221 and 99.72% +/-0.11 for first derivative method, for hydrochlorothiazide and olmesartan medoxomil, respectively. These methods are simple, accurate and rapid, those require no preliminary separation and can therefore be used for routine analysis of both drugs in quality control laboratories. PMID:20502567

Bhusari, K P; Khedekar, P B; Dhole, Seema; Banode, V S

2009-09-01

126

Derivative and Q-analysis Spectrophotometric Methods for Estimation of Hydrochlorothiazide and Olmesartan Medoxomil in Tablets  

PubMed Central

Two methods for simultaneous estimation of hydrochlorothiazide and olmesartan medoxomil in combined tablet dosage form have been developed. The first method is the application of Q–analysis method (absorbance ratio), which involves the formation of Q–absorbance equation at 264 nm (isobestic point) and at 271 nm, the maximum absorption of hydrochlorothiazide. The linearity ranges for hydrochlorothiazide and olmesartan medoxomil were 2.5-22.5 ?g/ml and 4-36 ?g/ml, respectively. The second method is based on the derivative spectrophotometric method at zero crossing wavelengths. The linearity ranges for hydrochlorothiazide and olmesartan medoxomil were 2.5-20 ?g/ml and 4-32 ?g/ml, respectively. The accuracy of the methods were assessed by recovery studies and was found to be 100.45% ±0.4215 and 100.24% ±0.3783 for absorbance ratio method and 99.39% ±0.221 and 99.72% ±0.11 for first derivative method, for hydrochlorothiazide and olmesartan medoxomil, respectively. These methods are simple, accurate and rapid, those require no preliminary separation and can therefore be used for routine analysis of both drugs in quality control laboratories.

Bhusari, K. P.; Khedekar, P. B.; Dhole, Seema; Banode, V. S.

2009-01-01

127

New spectrophotometric methods for the determination of moxifloxacin in pharmaceutical formulations.  

PubMed

Two rapid, simple and sensitive spectrophotometric methods for the quantitative analysis of moxifloxacin (MOX) in pharmaceutical formulations have been described. The first method (A) involves reaction of MOX with 1,2-naphthoquinone-4-sulphonate (NQS) in alkaline medium (pH 11.0) which results in an orange-coloured product exhibiting maximum absorption (lambda(max)) at 411 nm. The second method (B) is based on the oxidation of the MOX with a known excess of cerium (IV) sulfate and the residual oxidant is determined by treating with a fixed amount of methyl orange, and measuring the absorbance at 507 nm. The molar absorptivities for methods A and B were 4.9 x 10(3) and 6.5 x 10(4) L mol(-1) cm(-1), respectively. Under the optimized reaction conditions, Beer's law correlation of the absorbance with MOX concentration was obtained in the range of 2.5-20 and 0.5-30 microgmL(-1) for method A and B respectively. The intra-day precision expressed as relative standard deviation (RSD) was < 1.6% for both methods. The methods were validated in terms of accuracy and precision and were successfully applied to the determination of MOX in its pharmaceutical dosage form. The proposed methods are useful for routine analysis of MOX in quality control laboratories. PMID:23841346

Elbashir, Abdalla A; Ebraheem, Sara A M; Elwagee, Alawia H E; Aboul-Enein, Hassan Y

2013-01-01

128

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

129

Undergraduate Analytical Chemistry: To Use and Evaluate Organic Chelators for Spectrophotometric Determination of Iron  

Microsoft Academic Search

An analytical chemistry laboratory project to use and evaluate pyridyl? and triazine?containing chelators for spectrophotometric determination of iron is described. The “Iron Project” introduces students to UV?visible spectrophotometry and Beer's law via hands?on development and use of spectrophotometric methods for iron. Nine chelators are currently available for use. Students perform their proposed work, culminating in formal papers and posters. Student

Mark T. Stauffer

2007-01-01

130

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

2010-08-21

131

A new spectrophotometric method for the determination of tianeptine in tablets using ion-pair reagents.  

PubMed

A new rapid and sensitive procedure assay is proposed for the spectrophotometric determination of tianeptine. The developed method involves formation of colored chloroform extractable ion-pair complexes of tianeptine with bromophenol blue (BPB), bromocresol green (BCG), bromothymol blue (BTB) and methyl orange (MO) in acidic medium. Beer's law is obeyed in the concentration ranges 3.0-12.0, 4.0-16.0, 4.0-14.0 and 2.0-10.0 microg ml(-1) with BPB, BCG, BTB and MO, respectively. The detection limit of tianeptine was found to be 1.8 microg ml(-1) for BPB, 2.0 for BCG, 2.0 microg ml(-1) for BTB and 1.0 microg ml(-1) for MO. Validation of the method was performed in terms of linearity, limit of detection (LOD), quantification (LOQ), accuracy and precision. Common excipients used as additives in pharmaceutical preparations do not interfere in the proposed method. The proposed method has been applied to determination of the examined drugs in pharmaceutical formulations and the results demonstrated that the method is equally accurate, precise, and reproducible as the official method. The t-test showed no significant difference at 95% confidence level. PMID:19043231

Ulu, Sevgi Tatar; Aydogmus, Zeynep

2008-12-01

132

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

133

Chemometric and derivative methods as flexible spectrophotometric approaches for dissolution and assaying tests in multicomponent tablets.  

PubMed

Two derivative spectrophotometric (ratio derivative spectra and algorithm bivariate calibration) and a chemometric methods (partial least squares, PLS) are proposed for the simultaneous determination of binary mixtures in tablet analysis and dissolutions tests, without prior separation. These approaches are successfully applied to quantify trimethoprim (TMP) combined with sulfamethoxazole (SMX) or sulfamethazine (SMZ) or sulfafurazole (SFZ) using the information in the absorption spectra of appropriate solutions. Beer's law was obeyed in the concentration range of 0.98-17.5 microg/ml for TMP, 0.95-17.2 microg/ml for SMX, 1.16-17.5 microg/ml for SMZ and 0.97-17.4 microg/ml for SFZ. The first derivative (1D) bivariate algorithm method involves the use of four calibration curves: two for each compound at two different wavelengths, selected by Kaiser's method. Similarly, the first derivative ratio spectrophotometry employs the linear relationship between the ratio spectra of the analytes and the concentration range. The results were compared with those obtained by PLS multivariate calibration. The calibration models from PLS were pre-treated by orthogonal signal correction and evaluated by cross-validation using the 'SIMCA-P 9' software. Synthetic mixtures of TMP and sulfonamides were used in five different sets for the validity of the calibrations. Mean recoveries for derivative ratio, derivative bivariate and PLS methods were found to be between 99.7% and 102.0% for TMP, 99.4% and 100.2% for SMX, 99.3% and 101.0% for SMZ and 98.1% and 102.3% for SFZ. The calibrations of the three methods were successfully applied to the assaying and dissolution of placebo and commercial tablets without any prior separation. More than 85% of TMP, SMX and SMZ were dissolved within 15 min. For SFZ, only 85% of the compound was dissolved after 60 min. In this study, the three spectrophotometric methods can be satisfactorily used for the quantitative analysis and for dissolution tests of multicomponent dosage forms. PMID:15262532

Markopoulou, Catherine K; Malliou, Eleftheria T; Koundourellis, John E

2004-08-01

134

A kinetic spectrophotometric method for the determination of iron (III) in water samples  

NASA Astrophysics Data System (ADS)

A new kinetic spectrophotometric method has been developed for the determination of iron (III). The method is based on the catalytic effect of iron (III) on the oxidation of weak acid brilliant blue dye (RAWL) by KIO4 in acid medium. The advantages of the proposed method are that it is sensitive, accurate, rapid, inexpensive, can be operated under room temperature and has a large determination concentration range compared to other techniques. The obtained optimum conditions are: pH 3.15, RAWL (200 mgL-1) 5.00 mL, Potassium periodate solution (0.01 molL-1) 0.30 mL, phenanthroline (0.02 molL-1) 1.00 mL, reaction temperature 25°C and reaction time 7 min. With this method iron could quantitively be determined in the range 0.00 0.02 mgL-1, the detection limit being 4.10 × 10-10 g mL-1. The relative standard deviations (RSD) in five replicate determinations for 3 µgL-1 and 5 µgL-1 iron (III) are 3.1% and 1.9%, respectively. The method has been applied to the determination of iron (III) in tap water samples and seawater samples (from the South China Sea), the recovery rates being 98.0% and 100.5%, respectively.

Ji, Hongwei; Xu, Jian; Xin, Huizhen; Yang, Xiaoman

2008-05-01

135

Simultaneous Determination of Nitrate and Nitrite in Natural Water and Waste Water from Uranium Mines with Dual-Wavelength Spectrophotometric Method.  

National Technical Information Service (NTIS)

A new method is described for the simultaneous direct determination of nitrate and nitrite in natural water and waste water from uranium mines with dual-wavelength spectrophotometric method. The measuring wavelength and the referential wavelength are 219 ...

W. Jin Z. Yin M. Yao

1987-01-01

136

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

2005-08-18

137

A New extractive spectrophotometric method for determination of rizatriptan dosage forms using bromocresol green  

PubMed Central

Background and the purpose of the study Rizatriptan is used effectively for the treatment of migraine headache. In this study, a simple, rapid and low cost spectrophotometric method based on the ion-pair complexation is proposed for the determination of rizatriptan in raw material and dosage forms. Methods The ion-pair complexation using bromocresol green as reagent was performed in a buffer solution and the absorbance was measured by a spectrophotometer. The ion-pair formation conditions were optimized and the accuracy and precision of the method were calculated. Results and major conclusion Best results were achieved by using 6 ml of the bromocresol green reagent in the presence of phosphate buffer (pH?3.0). The stoichiometry of the resulted complex was 1:1. The within-day and between-day precision values were lower than 2.9 and 1.8 percent for the calibration range of 0.5–50 and 10–100 ?g/ml, respectively. The proposed method was successfully used for the determination of rizatriptan in dosage forms without any interference.

2013-01-01

138

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

2013-01-02

139

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

140

Development and validation of a spectrophotometric method for quantification of total glucosinolates in cruciferous vegetables.  

PubMed

Given their putative role in chemoprevention, validated methods are needed for quantification of total glucosinolates. Based on the colorimetric reaction of ferricyanide with 1-thioglucose, released by alkaline hydrolysis of glucosinolates, we developed a simple and sensitive method for spectrophotometric quantification of total glucosinolates in cruciferous vegetables. Lyophilized and ground vegetables are extracted with 80% boiling methanol. Extracted glucosinolates are isolated using a strong anion exchange column and then hydrolyzed with 2 N NaOH to release 1-thioglucose. Ferricyanide is added, and the decrease in absorbance is measured at 420 nm, with final values adjusted for background. Recovery of internal standard (sinigrin) was 107%. Intra- and interassay coefficients of variation were 5.4% and 15.8%, respectively. Dose response was linear with sinigrin and amount of plant material extracted (R(2) ? 0.99). Using sinigrin, the lower limit of quantification was 0.6 mg. This straightforward method may be an alternative to time-consuming and costly chromatographic methods. PMID:22313055

Gallaher, Cynthia M; Gallaher, Daniel D; Peterson, Sabrina

2012-02-07

141

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

142

Simple spectrophotometric method for determination of melamine in liquid milks based on green Mannich reaction  

NASA Astrophysics Data System (ADS)

A new and simple spectrophotometric method has been developed and validated for measuring the contamination of melamine in different milk products. The method is based upon measuring the absorption of the complex formed from melamine, 4-hydroxyacetophenone (Hap) and 1-pyrene carboxaldehyde (Pcd), which was adapted from the Mannich reaction. Quantitative analysis was done at a wavelength of 236 nm within a few minutes. The reaction was optimized by focusing on both obtaining high performance of the method and to concern the volatility and toxicity of used reagents. This method provided a linear dynamic range, limit of detection and limit of quantification of 0.100-3.78, 0.08 and 0.14 mg L-1, respectively. The relative standard deviation (RSD) was 3.6% (n = 10). The recoveries of melamine spiked liquid milk samples, with melamine concentrations of 0.63, 1.26, 1.89 and 2.52 mg L-1, were 87.7 ± 3.7%, 91.1 ± 8.8%, 89.2 ± 4.4% and 90.6 ± 3.6% (n = 3), respectively.

Chansuvarn, Woravith; Panich, Sirirat; Imyim, Apichat

2013-09-01

143

Novel Spectrophotometric Method for the Assay of Captopril in Dosage Forms using 2,6-Dichloroquinone-4-Chlorimide  

PubMed Central

A simple spectrophotometric method was developed for the determination of captopril (CPL) in pharmaceutical preparations. The method is based on coupling captopril with 2,6-dichloroquinone-4-chlorimide (DCQ) in dimethylsulphoxide. The yellow reaction product was measured at 443 nm. The absorbance–concentration plot was rectilinear over the range of 10-50 ?g/mL with minimum detection limit (LOD) of 0.66 ?g/mL and a quantification limit (LOQ) of 2.0 ?g/mL. The different experimental parameters affecting the development and stability of the color were carefully studied and optimized. The proposed method was successfully applied to the analysis of commercial tablets and the results were in good agreement with those obtained using official and reference spectrophotometric methods. Hydrochlorothiazide which is frequently co-formulated with CPL did not interfere with the assay. A proposal of the reaction pathway was presented.

El-Enany, Nahed; Belal, Fathalla; Rizk, Mohamed

2008-01-01

144

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

145

Spectrophotometric methods for the determination of sitagliptin and vildagliptin in bulk and dosage forms.  

PubMed

Simple, accurate and precise spectrophotometric methods have been developed for the determination of sitagliptin and vildagliptin in bulk and dosage forms. The proposed methods are based on the charge transfer complexes of sitagliptin phosphate and vildagliptin with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), 7,7,8,8-tetracyanoquinodimethane (TCNQ) and tetrachloro-1,4-benzoquinone (p-chloranil). All the variables were studied to optimize the reactions conditions. For sitagliptin, Beer's law was obeyed in the concentration ranges of 50-300 ?g/ml, 20-120 ?g/ml and 100-900 ?g/ml with DDQ, TCNQ and p-chloranil, respectively. For vildagliptin, Beer's law was obeyed in the concentration ranges of 50-300 ?g/ml, 10-85 ?g/ml and 50-350 ?g/ml with DDQ, TCNQ and p-chloranil, respectively. The developed methods were validated and proved to be specific and accurate for the quality control of the cited drugs in pharmaceutical dosage forms. PMID:23675221

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

2011-03-01

146

Spectrophotometric methods for the determination of the antidepressant drug paroxetine hydrochloride in tablets.  

PubMed

Simple, sensitive, and accurate visible spectrophotometric methods are described for the determination of paroxetine hydrochloride (PA) in tablets. Among them, the first 3 methods are based on the ion-pair complexes of PA formed with bromothymol blue (BTB), bromophenol blue (BPB), and bromocresol green (BCG) in aqueous acidic buffers. The complex species extracted into chloroform were quantitatively measured at 414 nm with BTB and BCG and at 412 nm with BPB. Beer's law was obeyed over the concentration ranges of 2-20, 2-16, and 2-16 microg/mL, respectively. The fourth method described is based on a coupling reaction between PA and 7-chloro-4-nitrobenzofurazon (NBD-Cl) in borate buffer, pH 8.5, in which a yellow reaction product that was measured at 478 nm was formed. The Beer's law range for this method was 2-10 microg/mL. The last method developed describes the interaction of PA base, as an n-electron donor, with 7,7,8,8-tetracyanoquinodimethane (TCNQ), as a pi-acceptor, in acetonitrile to give blue-colored TCNQ- radical anion with absorption maxima at 750 and 845 nm. Measured at 845 nm, the absorbance-concentration plot was rectilinear over the range of 1.5-15 microg/mL. The new methods developed were successfully applied to the determination of PA in tablets without any interference from common tablet excipients. The results of the methods were in good agreement with those obtained with an official liquid chromatographic method. This report describes first colorimetric methods for the determination of PA. PMID:15859076

Onal, Arma?an; Kepekçi, S Evrim; Oztunç, Aysel

147

Development and validation of spectrophotometric method for simultaneous estimation of paracetamol and lornoxicam in different dissolution media  

PubMed Central

Background: Paracetamol and lornoxicam in combined tablet dosage form are available in the market. This combination is used to treat inflammatory diseases of the joints, osteoarthritis and sciatica. Spectrophotometric and high performance liquid chromatography (HPLC) methods have been reported for their simultaneous estimation in tablet dosage form in specific solvent. This paper presents simple, accurate and reproducible spectrophotometric method for simultaneous determination of paracetamol and lornoxicam in tablet dosage form in different dissolution media. The reported method is helpful in determination of paracetamol and lornoxicam during dissolution study. Materials and Methods: Simple, sensitive, accurate and economical spectrophotometric method based on an absorption correction equation was developed for the estimation of paracetamol and lornoxicam simultaneously in tablet dosage form in different dissolution media at different pH. Results: Paracetamol showed absorption maxima at 243 nm in 0.1N HCland phosphate buffer pH 6.8, while lornoxicam showed absorption maxima at 374 nm in 0.1N HCland phosphate buffer pH 6.8. The linearity was obtained in the concentration range of 4-12 ?g/ml for paracetamol and 4-16 ?g/ ml for lornoxicam. Discussion: The concentrations of the drugs were determined by an absorption correction equation method. The results of analysis have been validated statistically by recovery studies.

Patel, Dasharath M.; Sardhara, Bhavesh M.; Thumbadiya, Diglesh H.; Patel, Chhagan N.

2012-01-01

148

Comparison of zero- and second-order derivative spectrophotometric and HPLC methods for the determination of gemcitabine in human plasma.  

PubMed

Zero- and second-order derivative spectrophotometric and high-performance liquid chromatography (HPLC) methods were developed and validated for the determination of gemcitabine in human plasma. Spectrophotometrically, gemcitabine was determined by means of zero-order derivative absorbance values (A) at 288 nm and from values from the second-order derivative absorbance values (2D) at 285 nm. Beer's Law was obeyed in the range 0.50-15.0 microg ml(-1). The proposed other method, normal-phase HPLC method for determination of gemcitabine in human plasma was described. Calibration curve was linear over the concentration range 0.20-15.0 microg ml(-1). Quantitation was achieved by diode array detection at 272 nm using 2'-deoxycytidine as internal standard. Results obtained by spectrophotometric and HPLC methods for determination of gemcitabine in human plasma described in this paper showed adequate accuracy, precision and repeatability. No interference was found in plasma at the selected derivative wavelength and chromatographic conditions. According to the statistical comparison, there is no significant difference between the three methods. This is suggested that the three methods are equally applicable. PMID:15120323

Yilmaz, Bilal; Kadio?lu, Yücel

2004-05-01

149

Evaluation of spectrophotometric and HPLC methods for shikimic acid determination in plants: models in glyphosate-resistant and -susceptible crops.  

PubMed

Endogenous shikimic acid determinations are routinely used to assess the efficacy of glyphosate in plants. Numerous analytical methods exist in the public domain for the detection of shikimic acid, yet the most commonly cited comprise spectrophotometric and high-pressure liquid chromatography (HPLC) methods. This paper compares an HPLC and two spectrophotometric methods (Spec 1 and Spec 2) and assesses the effectiveness in the detection of shikimic acid in the tissues of glyphosate-treated plants. Furthermore, the study evaluates the versatility of two acid-based shikimic acid extraction methods and assesses the longevity of plant extract samples under different storage conditions. Finally, Spec 1 and Spec 2 are further characterized with respect to (1) the capacity to discern between shikimic acid and chemically related alicyclic hydroxy acids, (2) the stability of the chromophore (t1/2), (3) the detection limits, and (4) the cost and simplicity of undertaking the analytical procedure. Overall, spectrophotometric methods were more cost-effective and simpler to execute yet provided a narrower detection limit compared to HPLC. All three methods were specific to shikimic acid and detected the compound in the tissues of glyphosate-susceptible crops, increasing exponentially in concentration within 24 h of glyphosate application and plateauing at approximately 72 h. Spec 1 estimated more shikimic acid in identical plant extract samples compared to Spec 2 and, likewise, HPLC detection was more effective than spectrophotometric determinations. Given the unprecedented global adoption of glyphosate-resistant crops and concomitant use of glyphosate, an effective and accurate assessment of glyphosate efficacy is important. Endogenous shikimic acid determinations are instrumental in corroborating the efficacy of glyphosate and therefore have numerous applications in herbicide research and related areas of science as well as resolving many commercial issues as a consequence of glyphosate utilization. PMID:21338087

Zelaya, Ian A; Anderson, Jennifer A H; Owen, Micheal D K; Landes, Reid D

2011-02-21

150

Determination of trace vanadium (V) in seawater and fresh water by the catalytic kinetic spectrophotometric method  

NASA Astrophysics Data System (ADS)

A new kinetic spectrophotometric method has been developed for the determination of vanadium (V). The method is based on the catalytic effect of vanadium (V) on the oxidation of weak acid brilliant blue dye (RAWL) by KBrO3 using the citric acid as activation reagent. The obtained optimum conditions are: c (RAWL) = 1×10-4 molL-1, c (KBrO3) = 3×10-2 molL-1, c (citric acid) = 9×10-3 molL-1, pH = 2.50, the reaction time being 7.0 min and the temperature being 25.0°C. Under the optimum conditions, the proposed method allows the determination of vanadium (V) in the range of 0-70.0 ng mL-1 and the detection limit is down to 0.407 ng mL-1. For standard vanadium (V) solution determination, the recovery efficiency is in the range of 98.5%-102% and the RSD ranges from 0.76%-1.25%. Moreover, it is demonstrated that most cations and anions do not interfere with the determination of vanadium (V) under the analytical condition. The new method was successfully applied in the determination of vanadium (V) in fresh water and seawater samples with satisfactory results. Vanadium (V) in the seawater samples from Qingdao offshore was determined using the method and the distribution of vanadium (V) was mapped. Compared with other instrumental analytical methods, the proposed method shows good selectivity, sensitivity, simplicity, lower cost and rapidity. It can be employed on shipboard easily.

Ji, Hongwei; Sha, Yuanyuan; Xin, Huizhen; Li, Shuang

2010-12-01

151

Simultaneous determination of hyoscine butylbromide and ketoprofen in pharmaceutical preparations by spectrophotometric and liquid chromatographic methods.  

PubMed

A binary mixture of hyoscine butylbromide and ketoprofen was determined by 4 different methods. The first involved determination of hyoscine butylbromide and ketoprofen using the ratio-spectra first-derivative spectrophotometric technique at 211 and 234 nm over the concentration ranges of 2-14 and 5-45 microg/mL with mean accuracies 99.84 +/-0.92 and 99.98+/- 0.64%, respectively. The second method utilized second-derivative spectrophotometry over the concentration ranges of 2-14 and 5-35 microg/mL with mean accuracies 99.32+/- 1.06 and 99.55+/-1.15%, respectively. The third method was based on the resolution of the 2 components by bivariate calibration depending on a simple and rapid mathematical algorithm and quantitative evaluation of the absorbances at 206 and 254 nm over concentration ranges of 2-16 and 5-35 microg/mL; mean accuracies of 100.21+/-1.30 and 100.19 +/-1.07% were obtained for hyoscine butylbromide and ketoprofen, respectively. The fourth method was reversed-phase liquid chromatography using 0.05 M ammonium dihydrogen phosphate-acetonitrile-methanol (20 + 30 + 6, v/v) as the mobile phase with ultraviolet detection at 220 nm over concentration ranges of 1-90 and 5-70 microg/mL; mean accuracies were 99.92+/-1.02 and 99.61+/- 0.98%, respectively. The suggested procedures were checked using laboratory-prepared mixtures and were successfully applied for the analysis of pharmaceutical preparations. The methods retained their accuracy and precision when the standard addition technique was applied. The results obtained by applying the proposed methods were statistically analyzed and compared with those obtained by the manufacturer's method. PMID:17373441

El-Saharty, Yasser Shaker; Metwally, Fadia H; Refaat, Mohamed; El-Khateeb, Sonia Zaki

152

[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

153

Flow analysis methods for the direct ultra-violet spectrophotometric measurement of nitrate and total nitrogen in freshwaters  

Microsoft Academic Search

Second derivative ultra-violet spectrophotometric methods are described for the measurement of nitrate and total nitrogen in freshwaters using flow analysis techniques. A simple flow system consisting of a peristaltic pump and a single-reflection flow-through cell was used for the measurement of nitrate. Quantification of total nitrogen using alkaline peroxodisulfate photo-digestion was achieved by incorporating an ultra-violet photo-reactor, a hollow-fibre filter

Brady S. Gentle; Peter S. Ellis; Michael R. Grace; Ian D. McKelvie

2011-01-01

154

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

155

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

156

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

PubMed

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 Pb(2+) 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 × 10(6) 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. PMID:21234287

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

2010-12-20

157

HPLC and chemometric assisted spectrophotometric methods for simultaneous determination of diprophylline, phenobarbitone and papaverine hydrochloride.  

PubMed

Three methods are developed for the simultaneous determination of diprophylline (DP), phenobarbitone (PH) and papaverine hydrochloride (PP). The chromatographic method depends on a high performance liquid chromatographic (HPLC) separation on a reversed-phase C18 column with a mobile phase consisting of 0.02 M potassium dihydrogen phosphate, pH 3.5--acetonitrile (55:45 v/v). Quantitation was achieved with UV detection at 210 nm based on peak area. The other two chemometric methods applied were principal component regression (PCR) and partial least squares (PLS-1). These approaches were successfully applied to quantify the three drugs in the mixture using the information included in the UV absorption spectra of appropriate solutions in the range 215-245 nm with the intervals Delta lambda = 0.2 nm. The calibration PCR and PLS-1 models were evaluated by internal validation (prediction of compounds in its own designed training set of calibration), by cross-validation (obtaining statistical parameters that show the efficiency for a calibration fit model) and by external validation over laboratory-prepared mixtures and pharmaceutical preparations. The PCR and PLS-1 methods require neither any separation step, nor any priori graphical treatment of the overlapping spectra of the three drugs in a mixture. The results of PCR and PLS-1 methods were compared with HPLC method obtained in pharmaceutical formulation and a good agreement was found. PMID:16023119

El-Gindy, Alaa

2005-09-01

158

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

159

Simple, Rapid, and Highly Sensitive Detection of Diphosgene and Triphosgene by Spectrophotometric Methods  

PubMed Central

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 µmol/L by UV and <0.4 µmol/L by fluorescence. The third method is a test strip for the simple and rapid detection and semi-quantitative estimation of diphosgene and triphosgene, using a filter paper embedded with dimethylbarbituric acid and poly(4-vinylpyridine). Addition of a test solution to the paper causes a color change from white to light blue at low concentrations and to pink at higher concentrations of triphosgene. The test strip is useful for quick on-site detection of triphosgene and diphosgene in reaction mixtures. The test strip is easy to perform and provides clear signal readouts indicative of the presence of phosgene precursors. The utility of this method was demonstrated by the qualitative determination of residual triphosgene during the production of poly(Bisphenol A carbonate).

Joy, Abraham; Anim-Danso, Emmanuel; Kohn, Joachim

2009-01-01

160

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

161

Estimation of phytotoxic aluminum in soil solution using three spectrophotometric methods  

Microsoft Academic Search

In the current investigation three spectrophotometric techniques -8-hydroxyquinoline, aluminon, and ferron- were compared for their ability to estimate phytotoxic Al in soil solution. Soil solution Al reacting with 8-hydroxyquinoline in 15 s, ferron in 30 s, and aluminon in 30 min were related to root and shoot growth of subterranean clover (Trifolium subterraneum L. cv. Mt. Barket) and switchgrass (Panicum

R. J. Wright; S. F. Wright

1987-01-01

162

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

163

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

2006-11-24

164

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

165

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

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

2011-03-01

166

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

PubMed

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 consisted of acetonitrile-methanol-phosphate buffer pH 4.50 (15:5:80, v/v/v) with flow rate 1 mL min(-1) and UV detection at 225 nm. The moclobemide was used as the internal standard. CE was performed using 75 microm x 82 cm fused silica capillary (65 cm effective), the internal standard was quetiapine. Detection was carried out at 225 nm. For aqueous analysis, the 30 mM phosphate buffer pH 6.00, 30 kV voltage and 30 degrees C temperature were chosen, non-aqueous determination was performed with ammonia acetate 1 mM in acetonitrile-methanol (1:1, v/v), 30 kV voltage and 25 degrees C temperature. NP-HPTLC was carried out using HPTLC silica F254 plates, developed with hexane-ethanol-propylamine (5:5:0.1, v/v/v) through 9 cm distance. RP-HPTLC was developed with HPTLC RP8F254 plates, with mobile phase of tetrahydrofuran-phosphate buffer pH 3.50 (4:6, v/v), distance 4.5 cm. Both analyses were performed in horizontal chambers and scanned with densitometer at 275 nm or videodensitometer at 254 nm. UV spectrophotometry was carried out in methanol, using 224 nm for direct assay and 258 nm (D1) for derivative assay. The precision and accuracy of all the methods were complexively compared. The highest accuracy was observed in RP-HPTLC, the highest precision was achieved in non-aqueous CE method. The differences were not significant, so all the elaborated methods can be used in routine analysis. PMID:17448345

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

2007-03-24

167

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

2004-12-19

168

Chemometric-assisted kinetic-spectrophotometric method for simultaneous determination of ascorbic acid, uric acid, and dopamine.  

PubMed

A chemometric-assisted kinetic spectrophotometric method has been developed for simultaneous determination of ascorbic acid (AA), uric acid (UA), and dopamine (DA). This method relies on the difference in the kinetic rates of the reactions of analytes with a common oxidizing agent, tris(1,10-phenanthroline) and iron(III) complex (ferritin, [Fe(phen)(3)](3+)) at pH 4.4. The changes in absorbance were monitored spectrophotometrically. The data obtained from the experiments were processed by chemometric methods of artificial neural network (ANN) and partial least squares (PLS). Acceptable techniques of prediction set, randomization t test, cross-validation, and Y randomization were applied for the selection of the best chemometric method. The results showed that feedforward artificial neural network (FFANN) is more efficient than the other chemometric methods. The parameters affecting the experimental conditions were optimized, and it was found that under optimal conditions Beer's law is followed in the concentration ranges of 4.3-74.1, 4.3-78.3, and 2.0-33.0 ?M for AA, UA, and DA, respectively. The proposed method was successfully applied to the determination of analytes in serum and urine samples. PMID:21078280

Moghadam, Masoud Rohani; Dadfarnia, Shayessteh; Shabani, Ali Mohammad Haji; Shahbazikhah, Parviz

2010-11-13

169

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

170

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

2012-04-12

171

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

Microsoft Academic Search

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 607nm. For glucose, hydrogen peroxide, generated by the oxidation of

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

2007-01-01

172

A sensitive spectrophotometric method for lead determination by flow injection analysis with on-line preconcentration  

Microsoft Academic Search

A new flow injection (FI) system for the determination of Pb(II) at trace level with a preconcentration step and spectrophotometric detection is proposed. It is based on preconcentration of lead ions on chitosan and dithizone–lead complex formation in aqueous medium (pH 9). The chemicals and FIA variables influencing the performance of the system were optimized and applied to the determination

Mar??a S Di Nezio; Miriam E Palomeque; Beatriz S Fernández Band

2004-01-01

173

Spectrophotometric information from the DIVA satellite  

NASA Astrophysics Data System (ADS)

The DIVA satellite will, in addition to the astrometry, obtain photometric data for about 40 million survey stars and spectral data for about a third of these. Relevant sections of the CCD-data stream will be transmitted to Earth to allow a photometric and a spectrophotometric analysis. The DIVA photometric (SM) data can be used to derive stellar colours. Colours are in particular required for the chromaticity correction of the astrometry. The UV telescope (UV) is designed to obtain information about the Balmer jump region of the spectral energy distribution. The spectrophotometric (SC) data consists of overlapping spectral orders in the cross-scan direction. From these SC images the dispi (dispersed position-coded intensity) will be derived. The information on all stellar parameters is, of course, contained in the dispi and can be extracted without deconvolution. CCDs of the type foreseen for DIVA are in the process of being tested for their performance under the special conditions of this space mission. Methods are being tested, like artificial neural networks (ANNs) and others, to derive the astrophysical parameters Teff, log g, [M/H], and E(B-V) from the dispi. We find that even with the relatively modest spectral resolution of the dispi the ANN can discriminate well in temperature, moderately well in gravity and extinction, and crudely in metallicity, all clearly dependent on the brightness of the star. Degeneracy in the temperature and extinction determination can be lifted especially using Balmer jump information from the DIVA UV telescope.

de Boer, K. S.; Willemsen, P. G.; Reif, K.; Poschmann, H.; Marien, K.-H.; Kaempf, T. A.; Hilker, M.; Evans, D. W.; Bailer-Jones, C. A. L.

2003-01-01

174

Methods for the determination of cyclopropenoid fatty acids V. A spectrophotometric method for cottonseed oils based upon the Halphen-test reaction  

Microsoft Academic Search

A spectrophotometric method of analysis for the quantitative estimation of cyclopropenoid fatty acids in cottonseed oil based\\u000a upon the Halphen-test reaction has been described. Various parameters involved in the reaction have been investigated and\\u000a two pigment fractions responsible for the characteristic Halphen-test cherry-red color have been isolated. The method is applicable\\u000a to relatively small amts of sample material. The average

A. V. Bailey; R. A. Pittman; F. C. Magne; E. L. Skau

1965-01-01

175

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

2013-04-30

176

A novel spectrophotometric method for determination of kinetic constants of aldehyde oxidase using multivariate calibration method  

Microsoft Academic Search

Although phenanthridine has been frequently used as a specific substrate for the assessment of aldehyde oxidase activity, the use of this method is questionable due to a lower limit of detection and its validity for kinetic studies. In the present study, a novel sensitive multivariate calibration method based on partial least squares (PLS) has been developed for the measurement of

Mohammad-Hossein Sorouraddin; Ebrahim Fooladi; Abdolhossein Naseri; Mohammad-Reza Rashidi

2008-01-01

177

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

178

Simultaneous determination of montelukast and loratadine by HPLC and derivative spectrophotometric methods.  

PubMed

In this study, high performance liquid chromatography (HPLC) and second derivative spectrophotometry have been used and described for the simultaneous determination of montelukast and loratadine in pharmaceutical formulations. HPLC separation was achieved with a Symmetry C18 column and sodium phosphate buffer (pH adjusted to 3.7): acetonitrile (20:80, v/v) as eluent, at a flow rate of 1.0 ml/min. UV detection was performed at 225 nm. The LC method is simple, rapid, selective and stability indicating for the determination of montelukast. 5-Methyl 2-nitrophenol was used as internal standard for the purpose of quantification of both the drugs in HPLC. In the second-order derivative spectrophotometry, for the determination of loratadine the zero-crossing technique was applied at 276.1 nm, but for montelukast peak amplitude at 359.7 nm (tangent method) was used. Both methods were fully validated and a comparison was made for assay determination of selected drugs in formulations. The results confirm that the methods are highly suitable for its intended purpose. PMID:12609675

Radhakrishna, T; Narasaraju, A; Ramakrishna, M; Satyanarayana, A

2003-02-26

179

Simultaneous spectrophotometric determination of paracetamol, ibuprofen and caffeine in pharmaceuticals by chemometric methods  

NASA Astrophysics Data System (ADS)

In this study, the simultaneous determination of paracetamol, ibuprofen and caffeine in pharmaceuticals by chemometric approaches using UV spectrophotometry has been reported as a simple alternative to using separate models for each component. Spectra of paracetamol, ibuprofen and caffeine were recorded at several concentrations within their linear ranges and were used to compute the calibration mixture between wavelengths 200 and 400 nm at an interval of 1 nm in methanol:0.1 HCl (3:1). Partial least squares regression (PLS), genetic algorithm coupled with PLS (GA-PLS), and principal component-artificial neural network (PC-ANN) were used for chemometric analysis of data and the parameters of the chemometric procedures were optimized. The analytical performances of these chemometric methods were characterized by relative prediction errors and recoveries (%) and were compared with each other. The GA-PLS shows superiority over other applied multivariate methods due to the wavelength selection in PLS calibration using a genetic algorithm without loss of prediction capacity. Although the components show an important degree of spectral overlap, they have been determined simultaneously and rapidly requiring no separation step. These three methods were successfully applied to pharmaceutical formulation, capsule, with no interference from excipients as indicated by the recovery study results. The proposed methods are simple and rapid and can be easily used in the quality control of drugs as alternative analysis tools.

Khoshayand, M. R.; Abdollahi, H.; Shariatpanahi, M.; Saadatfard, A.; Mohammadi, A.

2008-08-01

180

Development and validation of liquid chromatographic and ultraviolet derivative spectrophotometric methods for determination of epinastine hydrochloride in coated tablets.  

PubMed

High-performance liquid chromatographic (LC) and ultraviolet derivative spectrophotometric (UVD) methods were developed and validated for the quantitative determination of epinastine hydrochloride in coated tablets. LC was performed on a reversed-phase RP-18 column with a mobile phase composed of 0.3% triethylamine (pH adjusted to 4.0 with 10% orthophosphoric acid)-methanol (60 + 40, v/v). The first-order derivative method was performed at 243.8 nm using HCI and methanol as the solvent. The methods were validated according to U.S. Pharmacopoeia and International Conference on Harmonization guidelines. The statistical analysis by Student's t-test showed no significant difference between the results obtained by the 2 methods. The proposed methods were found to be simple, rapid, precise, accurate, robust, and sensitive, allowing perfect interchange. The LC and UVD methods can be used in the routine quantitative determination of the epinastine hydrochloride in coated tablets. PMID:17955971

Ghisleni, Daniela Dal Molim; Steppe, Martin; Schapoval, Elfrides E S

181

Determination of trace amounts of bromide by flow injection/stopped-flow detection technique using kinetic-spectrophotometric method.  

PubMed

A simple, sensitive and selective method for the determination of bromide in seawater by using a flow injection/stopped-flow detection technique was examined. The detection system was developed for a new kinetic-spectrophotometric determination of bromide in the presence of chloride matrix without any extraction and/or separation. The detection was based on the kinetic effect of bromide on the oxidation of methylene blue (MB) with hydrogen peroxide in a strongly acidic solution. Large amounts of chloride could enhance the sensitivity of the method as an activator. The decolorisation of the blue color of MB was used for the spectrophotometric determination of bromide at 746nm. A stopped-flow approach was used to improve the sensitivity of the measurement and provide good linearity of the calibration over the range of 0-3.2mugml(-1) of bromide. The relative standard deviation was 0.74% for the determination of 2.4mugml(-1) bromide (n=5). The detection limit (3sigma) was 0.1mugml(-1) with a sampling frequency of 12h(-1). The influence of potential interfering ions was studied. The proposed method was applied to the determination of bromide in seawater samples and provided satisfactory results. PMID:18970317

Uraisin, K; Nacapricha, D; Lapanantnoppakhun, S; Grudpan, K; Motomizu, S

2005-08-30

182

Simultaneous spectrophotometric determination of paracetamol and salicylamide in human serum and pharmaceutical formulations by a differential kinetic method.  

PubMed

A rapid, simple, and sensitive differential kinetic method is presented for the determinations of acetaminophen (also known as paracetamol) and salicylamide. The method is based on their oxidation reaction by Fe3+ ion in the presence of 1, 10-phenanthroline as indicator. The reactions can be monitored spectrophotometrically by measuring the increase in the absorbance of the solution at 510 nm. Two times were selected one in which only paracetamol is oxidized by Fe3+ ion and the other in which both drugs are oxidized by Fe3+ ion. The data were evaluated by the proportional equations method. The method allowed the simultaneous determination of paracetamol and salicylamide at concentrations between 0.5-20 and 1-40 microg/mL with relative standard deviations of 3.47 and 2.58%, respectively. The method was applied to the simultaneous determination of paracetamol and salicylamide in human serum and pharmaceutical formulations. PMID:16526453

Zarei, Ali Reza; Afkhami, Abbas; Sarlak, Nahid

183

Spectrophotometric and liquid chromatographic determination of fenofibrate and vinpocetine and their hydrolysis products.  

PubMed

Several spectrophotometric and HPLC methods are presented for the determination of fenofibrate, vinpocetine and their hydrolysis products. The resolution of either fenofibrate or vinpocetine and their hydrolysis products has been accomplished by using numerical spectrophotometric methods as partial least squares (PLS-1) and principal component regression (PCR) applied to UV spectra; and graphical spectrophotometric methods as first derivative of ratio spectra (1DD) or first (1D) and second (2D) derivative spectrophotometry for vinpocetine and fenofibrate, respectively. In addition HPLC methods were developed using ODS column with mobile phase consisting of acetonitrile-water (80:20, v/v, pH 4) with UV detection at 287 nm for fenofibrate and a mobile phase consisting of acetonitrile-10 mM KH2PO4, containing 0.1% diethylamine (60:40, v/v, pH 4.6) with UV detection at 270 nm for vinpocetine. The proposed methods were successfully applied for the determination of each drug and its hydrolysis product in laboratory-prepared mixture and pharmaceutical preparation. The proposed HPLC and derivative spectrophotometric methods were used to investigate the kinetics of acidic and alkaline hydrolytic processes of each drug. The pH-rate profile of hydrolysis of each drug in Britton-Robinson buffer solutions was studied. PMID:15910815

El-Gindy, Alaa; Emara, Samy; Mesbah, Mostafa K; Hadad, Ghada M

2005-05-01

184

Development and validation of new spectrophotometric ratio H-point standard addition method and application to gastrointestinal acting drugs mixtures.  

PubMed

New, simple, specific, accurate and precise spectrophotometric technique utilizing ratio spectra is developed for simultaneous determination of two different binary mixtures. The developed ratio H-point standard addition method (RHPSAM) was managed successfully to resolve the spectral overlap in itopride hydrochloride (ITO) and pantoprazole sodium (PAN) binary mixture, as well as, mosapride citrate (MOS) and PAN binary mixture. The theoretical background and advantages of the newly proposed method are presented. The calibration curves are linear over the concentration range of 5-60 ?g/mL, 5-40 ?g/mL and 4-24 ?g/mL for ITO, MOS and PAN, respectively. Specificity of the method was investigated and relative standard deviations were less than 1.5. The accuracy, precision and repeatability were also investigated for the proposed method according to ICH guidelines. PMID:23523762

Yehia, Ali M

2013-03-04

185

Development and validation of new spectrophotometric ratio H-point standard addition method and application to gastrointestinal acting drugs mixtures  

NASA Astrophysics Data System (ADS)

New, simple, specific, accurate and precise spectrophotometric technique utilizing ratio spectra is developed for simultaneous determination of two different binary mixtures. The developed ratio H-point standard addition method (RHPSAM) was managed successfully to resolve the spectral overlap in itopride hydrochloride (ITO) and pantoprazole sodium (PAN) binary mixture, as well as, mosapride citrate (MOS) and PAN binary mixture. The theoretical background and advantages of the newly proposed method are presented. The calibration curves are linear over the concentration range of 5-60 ?g/mL, 5-40 ?g/mL and 4-24 ?g/mL for ITO, MOS and PAN, respectively. Specificity of the method was investigated and relative standard deviations were less than 1.5. The accuracy, precision and repeatability were also investigated for the proposed method according to ICH guidelines.

Yehia, Ali M.

2013-05-01

186

Spectrophotometric system to develop a non-invasive method for monitoring of posidonia oceanica meadows  

NASA Astrophysics Data System (ADS)

Posidonia oceanica (L.) is an endemic phanerogam of the Mediterranean Sea. It lives between 0.2 and 40 m depth and make up extensive meadows that play a fundamental role in the marine coast ecosystem. Near the coasts at higher anthropic pressure, Posidonia meadows present both quality and quantity damages (regression) due to the mechanical operations on the seabed (anchoring, drag netting, pipe lines) and the sea pollution. Nowadays, the seagrass regression is monitored by different systems: aereophotografic, side scan sonar, underwater television camera, direct underwater visual inspection. Scientific community is looking for to develop monitoring systems more reliable, rapid and non invasive. Aim of this study is to evaluate the application of a new spectrophotometric imaging system based on the acquisition of reflectance spectral images with a good optical (250 Kpixels) and spectral resolution (spectral range 400-970 nm, a total of 115 single wavelength, 5 nm step each one). First trials were made on Posidonia's leafs to evaluate the system capacity to recognize spectral differences between samples picked up at two different depths (0.3 - 4 m). High discrimination percentage (90%) were found between leaf samples as function of the different depths, analyzing the spectral data by Partial Least Squares model. Forward activities will stress the system capability also to evaluate different phenol concentrations on Posidonia leaves, an important index of physiologic vegetal damage, through direct underwater spectrophotometric monitoring.

Menesatti, P.; Urbani, G.; Dolce, T.

2007-09-01

187

Methodes and apparature for precise measurements of solar UV radiation  

Microsoft Academic Search

The precise measurements of solar UV radiation are based on the use of the national primary standards of the flux, irradiance and spectral radiance. Standard sources and detectors were developed for the establishing of spectral and integral irradiance units for regions UV-A, -A1,-A2, -B, -C, herythemical, dangerous and other effective and UV irradiance. The primary standard detector is based on

S. Anevsky; V. Ivanov; O. Minaeva; O. Morozov; V. Sapritsky

2003-01-01

188

Spectrophotometric Methods Based on Charge Transfer Complexation Reactions for the Determination of Saxagliptin in Bulk and Pharmaceutical Preparation  

PubMed Central

Simple, accurate and precise spectrophotometric methods have been developed for the determination of saxagliptin in bulk and dosage forms. The proposed methods are based on the charge transfer complexes of saxagliptin with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and 7,7,8,8-tetracyanoquinodimethane (TCNQ). All the variables were studied to optimize the reactions’ conditions. Beer’s law was obeyed in the concentration ranges of 50-300 ?g/ml and 10-110 ?g/ml with DDQ and TCNQ, respectively. The developed methods were validated and proved to be precise and accurate for the quality control of the saxagliptinin its pharmaceutical dosage form.

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

2012-01-01

189

Kinetic spectrophotometric method for the determination of oxalic acid by its catalytic effect on the oxidation of safranine by dichromate  

NASA Astrophysics Data System (ADS)

A new catalytic kinetic spectrophotometric method for the determination of oxalic acid has been described based on its catalytic effect on the redox reaction between safranine and dichromate in dilute sulfuric acid media. The reaction is monitored photometrically by measuring the decrease in absorbance of safranine at the maximum wavelength of 530 nm. Under the optimum conditions, a calibration graph from 0.10 to 10.00 ?g ml -1 of oxalic acid with a detection limit of 0.08 ?g ml -1 was obtained. The relative standard deviation (R.S.D.) for ten replicate measurements of 1.0 and 5.0 ?g ml -1 oxalic acid was 2.7 and 2.5%, respectively. The purposed method is simple, sensitive, selective and inexpensive. The applicability of the proposed method was determined by the determination of oxalic acid in spinach and wastewater samples with satisfactory results.

Ensafi, Ali A.; Abbasi, S.; Rezaei, B.

2001-08-01

190

Spectrophotometric methods based on charge transfer complexation reactions for the determination of saxagliptin in bulk and pharmaceutical preparation.  

PubMed

Simple, accurate and precise spectrophotometric methods have been developed for the determination of saxagliptin in bulk and dosage forms. The proposed methods are based on the charge transfer complexes of saxagliptin with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and 7,7,8,8-tetracyanoquinodimethane (TCNQ). All the variables were studied to optimize the reactions' conditions. Beer's law was obeyed in the concentration ranges of 50-300 ?g/ml and 10-110 ?g/ml with DDQ and TCNQ, respectively. The developed methods were validated and proved to be precise and accurate for the quality control of the saxagliptinin its pharmaceutical dosage form. PMID:23675274

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

2012-09-01

191

Use of response surface methodology for development of new microwell-based spectrophotometric method for determination of atrovastatin calcium in tablets  

PubMed Central

Background Response surface methodology by Box–Behnken design employing the multivariate approach enables substantial improvement in the method development using fewer experiments, without wastage of large volumes of organic solvents, which leads to high analysis cost. This methodology has not been employed for development of a method for analysis of atorvastatin calcium (ATR-Ca). Results The present research study describes the use of in optimization and validation of a new microwell-based UV-Visible spectrophotometric method of for determination of ATR-Ca in its tablets. By the use of quadratic regression analysis, equations were developed to describe the behavior of the response as simultaneous functions of the selected independent variables. Accordingly, the optimum conditions were determined which included concentration of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), time of reaction and temperature. The absorbance of the colored-CT complex was measured at 460 nm by microwell-plate absorbance reader. The method was validated, in accordance with ICH guidelines for accuracy, precision, selectivity and linearity (r² = 0.9993) over the concentration range of 20–200 ?g/ml. The assay was successfully applied to the analysis of ATR-Ca in its pharmaceutical dosage forms with good accuracy and precision. Conclusion The assay described herein has great practical value in the routine analysis of ATR-Ca in quality control laboratories, as it has high throughput property, consumes minimum volume of organic solvent thus it offers the reduction in the exposures of the analysts to the toxic effects of organic solvents, environmentally friendly "Green" approach) and reduction in the analysis cost by 50-fold.

2012-01-01

192

Novel spectrophotometric method for determination of cinacalcet hydrochloride in its tablets via derivatization with 1,2-naphthoquinone-4-sulphonate  

PubMed Central

This study represents the first report on the development of a novel spectrophotometric method for determination of cinacalcet hydrochloride (CIN) in its tablet dosage forms. Studies were carried out to investigate the reaction between CIN and 1,2-naphthoquinone-4-sulphonate (NQS) reagent. In alkaline medium (pH 8.5), an orange red-colored product exhibiting maximum absorption peak (?max) at 490 nm was produced. The stoichiometry and kinetic of the reaction were investigated and the reaction mechanism was postulated. This color-developing reaction was employed in the development of a simple and rapid visible-spectrophotometric method for determination of CIN in its tablets. Under the optimized reaction conditions, Beer's law correlating the absorbance with CIN concentration was obeyed in the range of 3 - 100 ?g/ml with good correlation coefficient (0.9993). The molar absorptivity (?) was 4.2 × 105 l/mol/cm. The limits of detection and quantification were 1.9 and 5.7 ?g/ml, respectively. The precision of the method was satisfactory; the values of relative standard deviations (RSD) did not exceed 2%. No interference was observed from the excipients that are present in the tablets. The proposed method was applied successfully for the determination of CIN in its pharmaceutical tablets with good accuracy and precisions; the label claim percentage was 100.80 - 102.23 ± 1.27 - 1.62%. The results were compared favorably with those of a reference pre-validated method. The method is practical and valuable in terms of its routine application in quality control laboratories.

2012-01-01

193

Novel spectrophotometric method for determination of cinacalcet hydrochloride in its tablets via derivatization with 1,2-naphthoquinone-4-sulphonate.  

PubMed

This study represents the first report on the development of a novel spectrophotometric method for determination of cinacalcet hydrochloride (CIN) in its tablet dosage forms. Studies were carried out to investigate the reaction between CIN and 1,2-naphthoquinone-4-sulphonate (NQS) reagent. In alkaline medium (pH 8.5), an orange red-colored product exhibiting maximum absorption peak (?max) at 490 nm was produced. The stoichiometry and kinetic of the reaction were investigated and the reaction mechanism was postulated. This color-developing reaction was employed in the development of a simple and rapid visible-spectrophotometric method for determination of CIN in its tablets. Under the optimized reaction conditions, Beer's law correlating the absorbance with CIN concentration was obeyed in the range of 3 - 100 ?g/ml with good correlation coefficient (0.9993). The molar absorptivity (?) was 4.2 × 105 l/mol/cm. The limits of detection and quantification were 1.9 and 5.7 ?g/ml, respectively. The precision of the method was satisfactory; the values of relative standard deviations (RSD) did not exceed 2%. No interference was observed from the excipients that are present in the tablets. The proposed method was applied successfully for the determination of CIN in its pharmaceutical tablets with good accuracy and precisions; the label claim percentage was 100.80 - 102.23 ± 1.27 - 1.62%. The results were compared favorably with those of a reference pre-validated method. The method is practical and valuable in terms of its routine application in quality control laboratories. PMID:22305461

Darwish, Ibrahim A; Al-Shehri, Mona M; El-Gendy, Manal A

2012-02-03

194

Evaluation of chlorophyll fluorescence, in vivo spectrophotometric pigment absorption and ion leakage as biomarkers of UV-B exposure in marine macroalgae  

Microsoft Academic Search

The photosynthetic fluorescence ratio Fv:Fm, in vivo absorption spectra and ion leakage were evaluated as biomarkers of ambient and elevated UV-B (280 to 320?nm) exposure\\u000a of the intertidal alga Enteromorpha intestinalis (Chlorophyta) and the sublittoral alga Palmaria palmata (Rhodophyta). Measurements of thallus growth were also used to assess adverse biological effects. Ambient and elevated UV-B\\u000a significantly inhibited photosynthesis in both

B. Cordi; M. H. Depledge; D. N. Price; L. F. Salter; M. E. Donkin

1997-01-01

195

Spectrophotometric Reaction Rate Method for Determination of Oxalic Acid in Food Based on Its Enhancing Effect on the Oxidation of Pyrocathecol Violet by Dichromate  

Microsoft Academic Search

A simple kinetic spectrophotometric method for the determination of oxalic acid has been described, based on its catalytic effect on the oxidation of pyrocathecol violet (PCV) with potassium dichromate in acidic media. The reaction was monitored photometrically by measuring the decrease in absorbance of PCV at 450 nm. The influence of acid, PCV concentration, dichromate concentration, and temperature were studied

Ali A. Ensafi; M. Emadi

2004-01-01

196

Rapid and simple stability indicating HPLC method for the determination of cilazapril in pure substance and pharmaceutical formulation in comparison with classic and derivative spectrophotometric methods.  

PubMed

The present study describes development and subsequent validation of high performance liquid chromatographic method (HPLC) in comparison with spectrophotometric methods (classic, first, second and third order derivative) for determination of pure cilazapril in substance and pharmaceutical preparation. The main aim of this study was to find the method suitable not only for determination of cilazapril, but additionally useful in degradation kinetic study. Only the HPLC method is stability indicating. The HPLC method utilizes LiChroCART 250-4 HPLC-Cartridge, LiChrospher 100 RP-18 (5 ?m) column, at ambient temperature, eluted at the flow rate 1.0 mL/min. The mobile phase consists of acetonitrile, methanol and phosphate buffer (pH 2.0) (60:10:30, v/v/v). Wavelength of detection is set at 212 nm. Benzocaine is used as an internal standard. The second and third order derivative spectrophotometric methods can be applied for the cilazapril analysis in substance and tablet, but not for stability evaluation (the lack of selectivity towards degradation product). PMID:22568033

Paszun, Sylwia K; Stanisz, Beata; Paw?owski, Wojciech

197

Simultaneous determination of montelukast and loratadine by HPLC and derivative spectrophotometric methods  

Microsoft Academic Search

In this study, high performance liquid chromatography (HPLC) and second derivative spectrophotometry have been used and described for the simultaneous determination of montelukast and loratadine in pharmaceutical formulations. HPLC separation was achieved with a Symmetry C18 column and sodium phosphate buffer (pH adjusted to 3.7): acetonitrile (20:80, v\\/v) as eluent, at a flow rate of 1.0 ml\\/min. UV detection was

T Radhakrishna; A Narasaraju; M Ramakrishna; A Satyanarayana

2003-01-01

198

Spectrophotometric determination of organic nitrogen by a modified Lassaigne method and its application to meat products and baby food.  

PubMed

A modified Lassaigne method was developed for N determination based on fusion of the organic substance with metallic Na, conversion of the cyanide in the aqueous leachate to thiocyanate by ammonium polysulfide treatment, and colorimetric measurement of the thiocyanate formed by the addition of excessive ferric ions in acidic medium. The mean molar absorptivity of the Fe(NCS)2+ complex at 480 nm is 2.96 x 10(3) L/mol x cm, enabling quantitation of 0.25-7.72 ppm N (linear range) in the final solution. The relative amounts of Na, (NH4)2S2, and Fe(III) with respect to nitrogen in the analyte were optimized. The developed method was successfully applied to the determination of N in various brands of baby food, and it was compared statistically with the conventional Kjeldahl and elemental analysis methods. Protein nitrogen in a number of meat products was also precisely determined by the developed method. Thus, the total digestion time of the conventional Kjeldahl method was reduced considerably (e.g., to approximately 15 min for a dried sample) with a relatively simple spectrophotometric method requiring no sophisticated instrumentation. PMID:12180696

Demirata, Birsen; Apak, Resat; Afsar, Hüseyin; Tor, Izzet

199

Application and comparison of two-rate and differential kinetic methods in simultaneous spectrophotometric determination of ascorbic acid and L -cysteine in pharmaceutical samples  

Microsoft Academic Search

Two methods for the simultaneous determination of ascorbic acid (Asc) and L-cysteine (Cys) from kinetic spectrophotometric data are described and compared. The first is the two-rate method (TRM), and\\u000a the second, the differential kinetic method (DKM). Present in an excess amount, iron(III) is quantitatively reduced by Asc\\u000a or Cys to iron(II) that, in turn, interacts with phenanthroline (Phen) to form

J. Ghasemi; S. Nayebi

2006-01-01

200

A study of caffeine in tea. I. A new spectrophotometric micro-method. II. Concentration of caffeine in various strengths, brands, blends, and types of teas.  

PubMed

A new spectrophotometric micro-method for the determination of caffeine in tea is described. This method is then used to evaluate the caffeine content of a variety of brands and blends of bagged and loose hot tea prepared in different strengths and by different brewing methods. In addition, the caffeine content of instant tea, ice tea, and Mr. Coffee automatic tea is evaluated. PMID:707326

Groisser, D S

1978-10-01

201

Measurement of phenols dearomatization via electrolysis: The UV-Vis solid phase extraction method  

Microsoft Academic Search

Dearomatization levels during electrochemical oxidation of p-methoxyphenol (PMP) and p-nitrophenol (PNP) have been determined through UV-Vis spectroscopy using solid phase extraction (UV-Vis\\/SPE). The results show that the method is satisfactory to determine the ratio between aromatic compounds and aliphatic acids and reaction kinetics parameters during treatment of wastewater, in agreement with results obtained from numerical deconvolution of UV-Vis spectra. Analysis

Ronald Vargas; Carlos Borrás; Jorge Mostany; Benjamin R. Scharifker

2010-01-01

202

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

203

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

PubMed

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 × 10(4) and 12.3 × 10(4) 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. PMID:23041925

Ashour, Safwan; Bayram, Roula

2012-09-16

204

Kinetic spectrophotometric method as a new strategy for the determination of vitamin B 9 in pharmaceutical and biological samples  

NASA Astrophysics Data System (ADS)

In this study, a new method is proposed for the determination of trace amounts of folic acid (vitamin B 9). This method is based on the inhibitory effect of folic acid on the reaction of Thionine and bromate in sulfuric acid media. The reaction can be monitored spectrophotometrically by measuring the decrease in absorbance at 601 nm ( ?max). The effective variables on the reaction rate were investigated. Under optimum experimental conditions, the method allows to determine of the folic acid in a wide linear range with two linear segments. The limit of detection was 0.36 ?g mL -1 of folic acid. Relative standard deviations of six replicate determinations of 5.0 and 50.0 ?g mL -1 of folic acid were 1.18 and 1.02%, respectively. The interfering effect of the different species was also investigated. The method was evaluated by quantifying of folic acid in biological and pharmaceutical samples with satisfactory assay results.

Shishehbore, M. Reza; Sheibani, A.; Haghdost, A.

2011-10-01

205

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

206

Simple method for screening aflatoxin-producing molds by UV photography.  

PubMed Central

UV absorption by aflatoxins was monitored in GY agar medium by UV photography. In the UV photographs, aflatoxin-producing molds were identified as gray or black colonies, whereas aflatoxin-nonproducing molds appeared as white colonies. By cellophane transplantation experiments and silica gel thin-layer chromatography, the products absorbing UV light substantially were found to be mainly aflatoxins B1 and G1 excreted from the mold mycelium into the agar medium. UV absorption did not occur when the agar medium contained aflatoxin-noninducible carbon sources instead of glucose. Various inhibitors of aflatoxin production, such as dichlorovos and dimethyl sulfoxide, also decreased the intensity of UV absorption. These results indicate that this technique can be used as a simple, safe, and rapid method of screening aflatoxin-producing molds. Images

Yabe, K; Ando, Y; Ito, M; Terakado, N

1987-01-01

207

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.

2013-01-01

208

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

209

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

210

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

211

UV Radiometrie: Strahlungsquellen und Messverfahren (Ultraviolet Radiometry: Radiation Sources and Measuring Methods).  

National Technical Information Service (NTIS)

Measurements and measuring methods in the UV range (100 to 380 nm), used in industrial laboratories, are reviewed. The quantities that have to be measured usually are given. The different groups of UV sources are shown. The fundamentals of measurement of ...

V. Schaefer

1986-01-01

212

UV differential optical absorption method for measuring sulfur content in coal  

Microsoft Academic Search

Determining the sulfur content in coal rapidly and accurately can provide a technical basis for the enterprises and the environmental administration departments. A novel method for measuring the sulfur content in coal based on UV differential optical absorption is presented in this paper. However, compared with the applications in atmosphere monitoring, the UV differential optical absorption spectroscopy (DOAS) for the

Feihu Song; Chuanlong Xu; Shimin Wang

2012-01-01

213

Synchronous fluorescence, UV–visible spectrophotometric, and voltammetric studies of the competitive interaction of bis(1,10-phenanthroline)copper(II) complex and neutral red with DNA  

Microsoft Academic Search

Constant wavelength synchronous fluorescence spectroscopy (CW–SFS), UV–visible absorption spectroscopy, and cyclic and differential pulse voltammetry were applied to investigate the competitive interaction of DNA with the bis(1,10-phenanthroline)copper(II) complex cation ([Cu(phen)2]2+) and a fluorescence probe, neutral red dye (NR), in a tris–hydrogen chloride buffer (pH 7.4). The results show that both the [Cu(phen)2]2+and the NR molecules can intercalate competitively into the

Yongnian Ni; Daiqin Lin; Serge Kokot

2006-01-01

214

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

2012-11-02

215

Simultaneous spectrophotometric determination of rutin, quercetin and ascorbic acid in drugs using a Kalman Filter approach  

Microsoft Academic Search

A UV-spectrophotometric analysis of severely overlapped spectra yielded by anti-capillary fragility pharmaceutical materials, viz. rutin, quercetin and ascorbic acid, in authentic mixtures and in tablets or soft elastic capsules was proposed. The method was based on Kalman Filter calibration of either orthogonal experimental design, i.e. standard solutions containing only one component at a time, or non-orthogonal experimental design, i.e. standard

H. N. A Hassan; B. N Barsoum; I. H. I Habib

1999-01-01

216

A new spectrophotometric method for the determination of finasteride in tablets  

NASA Astrophysics Data System (ADS)

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 3.0-15.0, 3.0-15.0 and 5.0-20 ?g/mL with BPB, BCG and BTB, respectively. The detection limits of FIN was found to be 1.16 ?g/mL for BPB, 1.17 for BCG, 1.76 ?g/mL for BTB. All the methods gave similar results and were validated for selectivity, linearity, precision and sensitivity. The proposed methods were directly and easily applied to the pharmaceutical preparation with accuracy, resulting from recovery experiments between 100.11 and 100.33% for BPB, 100.17 and 100.67% for BCG and 100.33 and 100.60% for BTB methods. The low relative standard deviation values indicate good precision and high recovery values indicate accuracy of the proposed methods. The proposed methods have been applied to the determination of drug in commercial tablets. Results obtained from the analysis of commercial preparations with the proposed methods are in good agreement with those obtained with the official HPLC method.

Ulu, Sevgi Tatar

2007-07-01

217

A new spectrophotometric method for the determination of finasteride in tablets.  

PubMed

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 lambda(max). Beer's law is obeyed in the concentration ranges 3.0-15.0, 3.0-15.0 and 5.0-20 microg/mL with BPB, BCG and BTB, respectively. The detection limits of FIN was found to be 1.16 microg/mL for BPB, 1.17 for BCG, 1.76 microg/mL for BTB. All the methods gave similar results and were validated for selectivity, linearity, precision and sensitivity. The proposed methods were directly and easily applied to the pharmaceutical preparation with accuracy, resulting from recovery experiments between 100.11 and 100.33% for BPB, 100.17 and 100.67% for BCG and 100.33 and 100.60% for BTB methods. The low relative standard deviation values indicate good precision and high recovery values indicate accuracy of the proposed methods. The proposed methods have been applied to the determination of drug in commercial tablets. Results obtained from the analysis of commercial preparations with the proposed methods are in good agreement with those obtained with the official HPLC method. PMID:17035078

Ulu, Sevgi Tatar

2006-09-05

218

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

219

Spectrophotometric and fluorimetric methods for the determination of meloxicam in dosage forms  

Microsoft Academic Search

Four simple and accurate methods are presented for the determination of meloxicam in dosage forms. These methods are based on: the direct measurements of the differential spectra at 339.9–384.7 nm (A), the 1D-values at 322–368 nm and 2D-values at 343.2–385.6 nm (B), the formation of an ion-association complex between the drug and safranin T with subsequent absorption measurement at 518

Ekram M Hassan

2002-01-01

220

HPLC and chemometric-assisted spectrophotometric methods for simultaneous determination of atenolol, amiloride hydrochloride and chlorthalidone  

Microsoft Academic Search

Three methods are presented for the simultaneous determination of atenolol (AT), amiloride hydrochloride (AM) and chlorthalidone (CD). The high performance liquid chromatographic (HPLC) method depends on the separation of each drug on a reversed phase, RP 18 column. Elution was carried out with a mobile phase consisting of acetonitrile -5mM heptansulphonic acid sodium salt (20:80, v\\/v, pH 4.4). Quantitation was achieved

Alaa El-Gindy; Samy Emara; Ahmed Mostafa

2005-01-01

221

A rapid spectrophotometric method to determine beta-carotene content in cucumis melo  

Technology Transfer Automated Retrieval System (TEKTRAN)

The compound B-carotene is the predominant carotenoid in cantaloupe. Because of its antioxidant properties and health benefits, the B-carotene content in fruits and vegetables is of interest to the food industry. Current methods to assay B-carotene content in fruit are time consuming, expensive an...

222

A RAPID SPECTROPHOTOMETRIC METHOD TO DETERMINE ESTERASE ACTIVITY OF YEAST CELLS IN AN AQUEOUS MEDIUM  

Microsoft Academic Search

A new rapid method to determine the total esterase enzymatic activity of yeast cells is proposed. In a sodium phosphate buffer a p-naphthol synthetic ester is hydrolized by cells, and the released p- naphthol Is coupled with a diazonium salt (Fast Garnet GBC) in the presence of sodium dodecyl sulfate. The whole procedure Is carried out in an aqueous buffer

L. Bardi; V. Dell' oro; C. Delfini; M. Marzona

223

Modification of Amaya-Sugiura passive sampling spectrophotometric method of nitrogen dioxide determination in ambient air  

Microsoft Academic Search

On the example of the previously tested method of nitrogen dioxide determination in ambient air two aspects of wind influence on the badge-type sampler performance were discussed: an appropriate design of the sampler eliminating any open recess over the face of the sampler and so called “starvation effect” i.e. decrease in the mass of analyte absorbed by the sampler at

D. Krochmal; L. Górski

1991-01-01

224

Simultaneous determination of calcium and magnesium in water using artificial neural network spectro-photometric method  

NASA Astrophysics Data System (ADS)

A new analytical method using Back-Propagation (BP) artificial neural networks and spectrophotometry for simultaneous determination of calcium and magnesium in tap water, the Yellow River water and seawater is established. By condition experiment, the optimum analytical conditions for calcium, magnesium and Arsenazo (III) color reactions 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 11-10-2 (nodes). The initial value of gradient coefficient ? is fixed at 0.001 and the increase factor and reduction factor of ? 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 deviations of the calculated results for calcium and magnesium are 2.31% and 2.14%, respectively. The results of standard addition method show that the recoveries of calcium and magnesium are 103.6% and 100.8% in the tap water, 103.2% and 96.6% in the Yellow River water (Lijin district of Shandong Province), and 98.8%-103.3% and 98.43%-103.4% in seawater from Jiaozhou Bay of Qingdao. It is found that 14 common cations and anions do not interfere with the determination of calcium and magnesium under the optimum experimental conditions. The comparative experiments do not show any obvious difference between the results obtained by this new method and those obtained by the classical complexometric titration method in seawater medium. This method exhibits good reproducibility and high accuracy in the determination of calcium and magnesium and can be used for the simultaneous determination of Ca2+ and Mg2+ in tap water and natural water.

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

2010-09-01

225

Extractive spectrophotometric method for the determination of vanadium(V) in steels and titanium base alloy  

SciTech Connect

Vanadium(V) forms anionic chelates with 4-(2-pyridylazo)-resorcinol (PAR) at pH 5.0-7.8, which can be quantitatively extracted into nitrobenzene as an ion pair with xylometazolonium cation (XMH). The ternary system has an absorption maximum at 540 nm and obeys Beer's law in the range 0-1.8 /sup +/g of vanadium/mL with a molar absorptivity 4.56 x 10/sup 4/ L mol/sup -1/ cm/sup -1/. The Job's method of continuous variations indicated a composition of 1:1:1 for vanadium: PAR:XMH for the extracting species. In the presence of 1,3-diaminocyclohexanetetraacetic acid as a masking agent, the extraction becomes highly selective, and this method can be applied for the determination of vanadium(V), in the presence of various metal ions in synthetic mixtures, in steels, and in titanium base alloy.

Yerramilli, A.; Kavipurapu, C.S.; Manda, R.R.; Pillutla, C.M.

1986-06-01

226

Two derivative spectrophotometric methods for the simultaneous determination of lovastatin combined with three antioxidants  

Microsoft Academic Search

A zero crossing and an algorithm bivariate calibration derivative method for the simultaneous determination of lovastatin combined separately with three antioxidants (ascorbic acid, quercetin and gallic acid) in synthetic mixtures are described. The aqueous or methanolic solutions obeyed Beer's law in the concentration ranges of 3.20–17.36 ?g\\/ml for lovastatin, 1.76–8.80 ?g\\/ml for ascorbic acid, 1.41–7.04 ?g\\/ml for gallic acid and

C. K Markopoulou; J. E Koundourelllis

2003-01-01

227

HPLC methods for determination of dihydroxyacetone and glycerol in fermentation broth and comparison with a visible spectrophotometric method to determine dihydroxyacetone.  

PubMed

High-performance liquid chromatographic (HPLC) methods were respectively developed for the quantitative determination of dihydroxyacetone (DHA) and glycerol in the fermentation broth. Validation parameters such as linearity, precision, accuracy, and specificity, limit of detection (LOD), and limit of quantitation (LOQ) were determined. Both HPLC methods were carried out on a Lichrospher 5-NH2 column with a mobile phase constituted of acetonitrile and water (90:10, v/v). The linearity range for DHA was 2.00-12.00 mg/mL with a correlation coefficient (r) of 0.9994. The LOD and LOQ were 0.06 and 1.20 mg/mL, respectively. The linearity range for glycerol was 0.50-20.00 mg/mL with a correlation coefficient of 0.9998. The LOD and LOQ were 0.22 and 0.50 mg/mL, respectively. Also, the HPLC method to determine DHA was compared with an existing visible spectrophotometric method. Statistical analysis by F-test and t-test showed no significant difference at 95% confidence level between the two methods when applied to low DHA concentrations while a large deviation existed in the determinations of high DHA concentrations. The HPLC method was more accurate to determine high DHA concentrations. PMID:19007500

Chen, Jing; Chen, Jianhua; Zhou, Changlin

228

Simple Extraction and HPLC Determination of UVA and UV-B Filters in Sunscreen Products  

Microsoft Academic Search

The determination of 11 organic UV filters, worldwide authorised in sunscreen formulations, was performed by HPLC with UV spectrophotometric detection. The filters determined were: phenylbenzimidazole sulfonic acid, benzophenone-4, benzophenone-3, 4-methylbenzylidene camphor, ethylhexyl methoxycinnamate, octocrylene, methylene bis-benzotriazolyl tetramethylbutyl phenol, butyl methoxydibenzoylmethane, bis-ethylhexyloxyphenol methoxyphenyltriazine, ethylhexyl triazone, and diethylamino hydroxybenzoyl hexyl benzoate. Three analytical methods were developed which were based on an ultrasonic

D. De Orsi; G. Giannini; L. Gagliardi; R. Porrà; S. Berri; A. Bolasco; I. Carpani; D. Tonelli

2006-01-01

229

A validated method for development of atovaquone as API and tablet dosage forms by UV spectroscopy  

PubMed Central

A simple new spectrophotometric method has been developed for estimation of Atovaquone in bulk and tablet dosage form. Atovaquone is estimated to be 251 nm in methanol. The Beer's law is obeyed in the concentration range of 1–10 ?g/mL of the drug. The slope and intercept values are 0.111 and 0.012, respectively. Results of analysis of this method have been validated statically and by recovery studies. The method is applied to the marketed tablet formulation. A result of the analysis of tablet formulation, given as a percentage of label claim ± standard deviation, is 99.14 ± 0.66. The precision and accuracy has been examined by performing recovery studies and found to be 100.09 ± 1.14. The developed method is simple, sensitive, and reproducible, and can be used for the routine analysis of Atovaquone in bulk and tablet dosage form.

Patel, Kalpesh N; Patel, Jayvadan K; Patel, Manish P; Rajput, Ganesh C

2010-01-01

230

Extractive spectrophotometric method for the determination of vanadium(V) in steels and titanium base alloy  

Microsoft Academic Search

Vanadium(V) forms anionic chelates with 4-(2-pyridylazo)-resorcinol (PAR) at pH 5.0-7.8, which can be quantitatively extracted into nitrobenzene as an ion pair with xylometazolonium cation (XMH). The ternary system has an absorption maximum at 540 nm and obeys Beer's law in the range 0-1.8 \\/sup +\\/g of vanadium\\/mL with a molar absorptivity 4.56 x 10⁴ L mol⁻¹ cm⁻¹. The Job's method

Anjaneyulu. Yerramilli; C. S. Kavipurapu; R. R. Manda; C. M. Pillutla

1986-01-01

231

Spectrophotometrical method of ordering estimation for liquid crystal in an electro-optical cell  

NASA Astrophysics Data System (ADS)

The present work is devoted to the order parameter S estimation in the comb-shaped liquid crystal polymer thin films. The plymer under study was placed in the electrooptical cell and its homeotropical orientation was realized by the action of electrical field between the electrodes. The polarization absorption spectra of the empty cell and the cell with polymer were investigated at different incidence angles of the light beam. The method of interferometric extremum envelopes was used for the processing of the quasiperiodical absorption spectra observed. This method gives the possibility to obtain the optical parameters of the cell electrodes and to re- establish the true polarization spectrum of the polymer film. The polymer order parameter S was calculated from the dichroic ratio for the polymer absorption band at revealed (lambda) = 405 nm. The refractive index dispersion data obtained for the substrates and the polymer from the independent measurements were used for this purpose. The effects of the local field on the order parameter value were also taken into account.

Kiselev, Dmitrii F.; Glushkova, Tatiana M.; Ivanov, Sergei; Firsova, Marina M.; Shtyrkova, Antonina P.

2001-03-01

232

Development of an reliable analytical method for synergistic extractive spectrophotometric determination of cobalt(II) from alloys and nano composite samples by using chromogenic chelating ligand  

Microsoft Academic Search

A synergistic simple and selective spectrophotometric method was developed for the determination of cobalt(II) with 1-(2?,4?-dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol [2?,4?-dinitro APTPT] as a chromogenic reagent. The proposed method has been described on the basis of synergistic effective extraction of cobalt(II) in presence of pyridine at pH range 9.5–10.2, showed orange-red coloured ternary complex having molar ratio 1:2:2 (M:L:Py). The equilibrium time is

Ganesh S. Kamble; Anita A. Ghare; Sanjay S. Kolekar; Sung H. Han; Mansing A. Anuse

233

Estimation of menthol in Pan Masala samples by a spectrophotometric method.  

PubMed

Recently, the Prevention of Food Adulteration Act of India has fixed the level of menthol addition to Pan Masala at 0.1%, therefore good manufacturing practice (GMP) should be adopted so that the samples do not exceed 0.1% menthol (1 mg/g). The estimation of menthol in Pan Masala samples involves steam distillation followed by reaction with p-dimethyl amino benzaldehyde (DMAB) in acidic medium to give a red colour which is read at 550 nm. The sensitivity of this procedure is 75 micrograms menthol per g sample. Using this method, 130 branded and 53 non-branded samples of Pan Masala were analysed for menthol content. Almost 25% of branded samples contained less than 1 mg menthol per g while 75% of samples contained 1.1-6.5 mg menthol per g Pan Masala. Non-branded Pan Masala contained 1 mg menthol per g in only 7.6% of samples. However, 92% of samples contained 1.1-6.5 mg menthol per g, suggesting that the addition of menthol is relatively higher in non-branded Pan Masala samples than in branded ones. PMID:9205565

Kannan, A; Das, M; Khanna, S K

234

Determination of metoprolol and hydrochlorothiazide by derivative spectrophotometric method in pharmaceutical preparations.  

PubMed

A procedure for simultaneous determination of metoprolol and hydrochlorothiazide in tablets by employing derivative spectrophotometry, "zero-crossing" method was developed. The third order derivative absorption spectra at lambda approximately 281 nm were used for metoprolol and the first order derivative spectra at lambda approximately 282 nm were used for hydrochlorothiazide. No interferences were found between both determined constituents and those of matrix. A good accuracy and precision of simultaneous determination of metoprolol and hydrochlorothiazide were confirmed by statistical analysis. The recovery of individual constituents under established conditions is very high and ranges from 98.79% to 99.39%. Linearity is maintained within a wide concentration range from 100.0 microg mL(-1) to 300.0 microg mL(-1) and from 12.5 microg mL(-1) to 37.5 microg mL(-1) for metoprolol and hydrochlorothiazide, respectively. The detection limit is 5.0 microg mL(-1) for metoprolol and 1.5 microg mL(-1) for hydrochlorothiazide. The corresponding quantitation limits are 15.0 microg mL(-1) for metoprolol and 4.5 microg mL(-1) for hydrochlorothiazide. PMID:20085220

Stolarczyk, Mariusz; Ekiert, Rados?aw; Krzek, Jan; Rzeszutko, W?odzimierz

235

Extractive spectrophotometric methods for the determination of nifedipine in pharmaceutical formulations using bromocresol green, bromophenol blue, bromothymol blue and eriochrome black T.  

PubMed

Four simple, sensitive and accurate spectrophotometric methods have been developed for the determination of nifedipine in pharmaceutical formulations. These methods are based on the formation of ion-pair complexes of amino derivative of the nifedipine with bromocresol green (BCG), bromophenol blue (BPB), bromothymol blue (BTB) and eriochrome black T (EBT) in acidic medium. The coloured products are extracted with chloroform and measured spectrophotometrically at 415 nm (BCG, BPB and BTB) and 520 nm (EBT). Beer's law was obeyed in the concentration range of 5.0-32.5, 4.0-37.5, 6.5-33.0 and 4.5-22.5 microg ml(-1) with molar absorptivity of 6.41 x 10(3), 4.85 x 10(3), 5.26 x 10(3) and 7.69 x 10(3) l mol(-1) cm(-1) and relative standard deviation of 0.82%, 0.72%, 0.66% and 0.68% for BCG, BPB, BTB and EBT methods, respectively. These methods have been successfully applied for the assay of drug in pharmaceutical formulations. No interference was observed from common pharmaceutical adjuvants. Statistical comparison of the results with the reference method shows excellent agreement and indicates no significant difference in accuracy and precision. PMID:14751316

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

2004-01-01

236

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.

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

2012-01-01

237

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

PubMed

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 × 10(4)?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 × 10(4)?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

2012-02-27

238

A method for UV-bonding in the fabrication of glass electrophoretic microchips.  

PubMed

This paper presents an approach for the development of methodologies amenable to simple and inexpensive microchip fabrication, potentially applicable to dissimilar materials bonding and chip integration. The method involves a UV-curable glue that can be used for glass microchip fabrication bonding at room temperature. This involves nothing more than fabrication of glue "guide channels" into the microchip architecture that upon exposure to the appropriate UV light source, bonds the etched plate and cover plate together. The microchip performance was verified by capillary zone electrophoresis (CZE) of small fluorescent molecules with no microchannel surface modification carried out, as well as with a DNA fragment separation following surface modification. The performance of these UV-bonded electrophoretic microchips indicates that this method may provide an alternative to high temperature bonding. PMID:11700722

Huang, Z; Sanders, J C; Dunsmor, C; Ahmadzadeh, H; Landers, J P

2001-10-01

239

Spectrophotometric pH measurements of freshwater  

Microsoft Academic Search

The use of cresol red (CR) indicator for determination of freshwater pH is evaluated. Ionic strength effects and indicator pH perturbation are discussed and quantified using theoretical and empirical approaches. Spectrophotometric and potentiometric methods are directly compared by repeated analyses of a low ionic strength pH buffer. The mean and standard deviation of the two methods were 7.618±0.008 (spectrophotometric) and

Craig R French; Jeffrey J Carr; Eleanor M Dougherty; Lisa A. K Eidson; Jason C Reynolds; Michael D DeGrandpre

2002-01-01

240

An experimental method for determining the UV susceptibility of airborne microorganisms using an upper room UV field  

Microsoft Academic Search

With the global rise in tuberculosis cases, coupled with the emergence of strains of Mycobacterium tuberculosis which are multiply-antibiotic resistant, interest has been renewed in the use of upper-room UV systems to control the spread of airborne infection. Whilst a number of researchers have demonstrated that upper-room UV fields might be effective, it is technically difficult to determine the performance

CB Beggs; LA Fletcher; PA Sleigh; KG Kerr; CJ Noakes

241

Simultaneous Spectrophotometric Estimation of Tenofovir Disoproxil Fumarate and Lamivudine in Three Component Tablet Formulation Containing Efavirenz  

PubMed Central

Three UV spectrophotometric methods have been developed, simultaneous equation method, multicomponent analysis (II) and derivative spectroscopy method (III). The absorption maxima of the drugs were found to be 247, 259 and 272 nm, respectively for efavirenz, tenofovir disoproxil fumarate and lamivudine in methanol:water (50:50) solvent system. Efavirenz, tenofovir disoproxil fumarate and lamivudine obeyed Beer’s law in the concentration range of 10-60, 5-30 and 5-30 ?g/ml, respectively. Results of analysis for all the three methods were analyzed and validated for various parameters according to ICH guidelines.

Sharma, R.; Mehta, K.

2010-01-01

242

An Experimental Method to Investigate the Optimal UV Filter for the Auger Fluorescence Detectors  

Microsoft Academic Search

A specic experimental method, in order to investigate the more suit- able UV lter to install in the Fluorescence Detector (FD) of the AUGER Project, is presented in this work. A prototype experimental setup has been developed for this purpose. As detector, it uses an elementary cell, similar to the one used in the FD. A fast and sensitive photon

S. Maltezos; E. Fokitis

2000-01-01

243

New Spectrophotometric Method for Determining Nitrogen Dioxide in Air Using 2,2-azino-bis(3-ethyl benzothiazoline)-6-Sulfonic Acid-Diammonium Salt and Passive Sampling  

PubMed Central

A new simple and highly sensitive spectrophotometric method for determining nitrogen dioxide in air was developed. The method is based on converting atmospheric nitrogen dioxide to nitrite ions within the IVL passive samplers used for samples collection. Acidifying nitrite ions with concentrated HCl produced the peroxynitrous acid oxidizing agent which was measured using 2, 2-azino-bis(3-ethyl benzothiazoline)-6-sulfonic acid-diammonium salt (ABTS) as reducing coloring agent. A parallel series of collected samples were measured for its nitrite content using a validated ion chromatographic method. The results obtained using both methods were compared in terms of their sensitivity and accuracy. Developed spectrophotometric method was shown to be one order of magnitude higher in sensitivity compared to the ion chromatographic method. Quantitation limits of 0.05 ppm and 0.55 ?g/m3 were obtained for nitrite ion and nitrogen dioxid, respectively. Standard deviations in the ranges of 0.05–0.59 and 0.63–7.92 with averages of 0.27 and 3.11 were obtained for determining nitrite and nitrogen dioxide, respectively. Student-t test revealed t-values less than 6.93 and 4.40 for nitrite ions and nitrogen dioxide, respectively. These values indicated insignificant difference between the averages of the newly developed method and the values obtained by ion chromatography at 95% confidence level. Compared to continuous monitoring techniques, the newly developed method has shown simple, accurate, sensitive, inexpensive and reliable for long term monitoring of nitrogen dioxide in ambient air.

Salem, Alaa A.; Soliman, Ahmed A.; El-Haty, Ismail A.

2011-01-01

244

Quantitative HPLC-UV method for the determination of firocoxib from horse and dog plasma  

Microsoft Academic Search

A sensitive reversed-phase HPLC-UV method was developed for the determination of firocoxib, a novel and highly selective COX-2 inhibitor, in plasma. A 1.0mL dog or horse plasma sample is mixed with water and passed through a hydrophobic–lipophilic copolymer solid-phase extraction column to isolate firocoxib. Quantitation is based on an external standard curve. The method has a validated limit of quantitation

Valerie Kvaternick; Thomas Malinski; Jill Wortmann; James Fischer

2007-01-01

245

Kinetics and reaction pathways of formaldehyde degradation using the UV-fenton method.  

PubMed

This study was based on the purpose of investigating the reaction rules of formaldehyde (HCHO) as an intermediate product in the degradation of many other organic wastewaters. The process conditions of UV-Fenton method for the degradation of the low concentrations of HCHO were studied in a batch photochemical reactor. The results showed that, when the original HCHO concentration was 30 mg/L, at an operating temperature of 23 degrees C, pH = 3, an H202 dosage of 68 mg/L, and an H2O2-to-Fe2+ mole ratio (H2O2:Fe2+) of 5, 91.89% of the HCHO was removed after 30 minutes. The degradation of HCHO in the UV-Fenton system was basically in accordance with the exponential decay. The kinetic study results showed that the reaction orders of HCHO, Fe2+, and H2O2 in the system were 1.054, 0.510, and 0.728, respectively, and the activation energy (Ea) was 9.85 kJ/mol. The comparison of UV/H2O2, Fenton, and UV-Fenton systems for the degradation of HCHO, and the results of iron catalyst tests showed that the mechanism of UV-Fenton on the degradation of HCHO was through a synergistic effect of Fe2+ and UV light to catalyze the decomposition of H2O2. The introduction of UV irradiation to the Fenton system largely increased the degradation rate of HCHO, mainly as a result of the accelerating effect on the formation of the Fe2+/Fe3+ cycle. The reaction products were analyzed by gas chromatography-mass spectrometry and a chemical oxygen demand (COD) analyzer. The effluent gases also were analyzed by gas chromatography. Based on those results, the reaction pathways of HCHO in the UV-Fenton system were proposed. The qualitative and quantitative analysis of the reaction products and the COD showed that the main intermediate product of the reaction was formic acid, and the further oxidation of it was the rate-limiting step for the degradation of HCHO. PMID:21657193

Liu, Xiangxuan; Liang, Jiantao; Wang, Xuanjun

2011-05-01

246

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

247

Direct spectrophotometric determination of diacerhein in capsules.  

PubMed

A simple, rapid and precise ultraviolet spectrophotometric method using 0.1 N sodium hydroxide has been developed and validated for the assay of diacerhein. The drug can be estimated at 277 nm (ultraviolet region, UV) as well as at 502 nm (visible region, VIS). The absorbances were linearly correlated with concentration in the 6.0-24 microg mL(-1) range (r = 0.9999) and 10-34 microg mL(-1) range (r = 0.9998), respectively at 277 and at 502 nm. The relative standard deviation values for intra (n = 6) and inter-day (n = 3) precision were <2%. Recoveries ranged between 99.0 and 101.7%. The method has been successfully applied to the drug assay in capsules. It was also found that the excipients in the commercial capsules did not interfere with the method. Statistical analysis showed no significant difference between the results obtained at two wavelengths (277 nm or 502 nm). PMID:17718185

Borgmann, S H M; Parcianello, L M; Arend, M Z; Cardoso, S G

2007-07-01

248

Isolation of UV-sensitive mutants of mouse L5178Y cells by a cell suspension spotting method  

SciTech Connect

We have isolated 56 UV-sensitive mutant clones from a mouse L51 T/t line of L5178Y cells by a cell suspension spotting method. Five mutants have also been isolated from L51 T/t and L5178Y cells by the method reported by Thompson and coworkers. We divided the mutants into two groups, highly sensitive and moderately sensitive mutants, according to their sensitivity to UV irradiation. Fifty-eight mutants were highly sensitive and three were moderately sensitive to UV. The reconstruction experiments indicate that more than 90% of highly sensitive mutants were recovered by the cell suspension spotting method. Frequencies of recovered mutants highly sensitive to UV increased with increasing dose of mutagens. Recovered mutant frequency reached 10(-2) after treatment with 1.5 micrograms/ml of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) (survival 0.2%). Eight UV-sensitive mutants were divided into four complementation groups. These mutants were 2-6 times more sensitive to UV than parental L51 T/t cells in terms of D37 (dose required to reduce survival to 37%). Four representative UV-sensitive mutants which are classified into different complementation groups were examined for their sensitivity to killing by UV, 4-nitroquinoline-1-oxide (4NQO), mitomycin C (MMC), X-rays, and MNNG. All four classes of mutants were found to be cross-sensitive to UV, 4NQO, and MMC, but not sensitive to X-rays and MNNG.

Shiomi, T.; Hieda-Shiomi, N.; Sato, K.

1982-05-01

249

Characterization of UV curable hybrid hard coating materials prepared by sol-gel method  

Microsoft Academic Search

Using sol-gel method, UV-curable urethane acrylate resin system was hybridized with inorganic silicate network to produce\\u000a hybrid coating materials with high anti-abrasive property. In preparation of acrylate\\/SiO2 hybrid materials, various acrylic reactants with multi-functional groups in addition to urethane acrylate oligomer as the\\u000a main network former were employed to obtain more densified organic network structure with a high degree of

Seong Woo Kim

2011-01-01

250

UV Curable Hard Transparent Hybrid Coating Materials on Polycarbonate Prepared by the Sol-Gel Method  

Microsoft Academic Search

UV curable, hard, transparent inorganic\\/organic composites with covalent links between the inorganic and the organic networks were prepared by the sol-gel method. These hybrid coating materials were synthesized using a commercially available, acrylate end-capped polyester or polyurethane oligomeric resin (EBC80, EBC284), hexanedioldiacrylate (HDDA) as a reactive solvent, 3-(trimethoxysilyl)propoxymethacrylate (TMSPM) as a coupling agent between the organic and inorganic phase, and

J. Gilberts; A. H. A. Tinnemans; M. P. Hogerheide; T. P. M. Koster

1998-01-01

251

Spectrophotometric determination of carvedilol in pharmaceutical formulations through charge-transfer and ion-pair complexation reactions.  

PubMed

Simple extraction-free spectrophotometric methods have been developed for the determination of carvedilol (CAR). The methods were based either on charge-transfer reaction of the drug with the sigma-acceptor iodine, in acetonitrile, or on ion-pair formation with the acidic sulphophthalein dyes bromothymol blue (BTB) and bromocresol green (BCG), in chloroform. The obtained complexes showed absorbance maxima at 363, 411 and 414 nm, respectively for iodine, BTB and BCG. Beer's law validation, accuracy, precision, and other aspects of analytical merit are presented in the text. The proposed methods were applied for the determination of CAR in tablets and compounded capsules. The results were in good agreement with those obtained by an established UV spectrophotometric method. PMID:17294810

Cardoso, S G; Ieggli, C V S; Pomblum, S C G

2007-01-01

252

A membraneless gas-diffusion unit-multisyringe flow injection spectrophotometric method for ammonium determination in untreated environmental samples.  

PubMed

A new design of a membraneless gas-diffusion (MGD) unit coupled to a multisyringe flow injection system is proposed. The spectrophotometric determination of ammonium using an acid-base indicator was chosen to show the feasibility of this approach. Hence, in alkaline medium, ammonium ions are transformed into ammonia (donor channel) which diffuses through the headspace into the acceptor stream (bromothymol blue solution), causing a pH change and subsequently a colour change. The exploitation of the enhanced potentialities of this re-designed MGD device was the main purpose of the present work. Hence, several strategies concerning flow management were studied seeking to characterize and improve the analytical features of the methodology and moreover, untreated environmental samples were analysed without previous filtration. Consequently, stopped flow in acceptor channel with continuous flow in donor channel was chosen for the application to wastewater and spiked river water samples. A linear concentration range between 10.0 and 50.0 mg L(-1) of NH(4)(+), a limit of detection of 2.20 mg L(-1) and a determination frequency of 11h(-1) were obtained. PMID:21641433

Almeida, M Inês G S; Estela, José Manuel; Segundo, Marcela A; Cerdà, Víctor

2011-01-21

253

Development of an reliable analytical method for synergistic extractive spectrophotometric determination of cobalt(II) from alloys and nano composite samples by using chromogenic chelating ligand  

NASA Astrophysics Data System (ADS)

A synergistic simple and selective spectrophotometric method was developed for the determination of cobalt(II) with 1-(2',4'-dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol [2',4'-dinitro APTPT] as a chromogenic reagent. The proposed method has been described on the basis of synergistic effective extraction of cobalt(II) in presence of pyridine at pH range 9.5-10.2, showed orange-red coloured ternary complex having molar ratio 1:2:2 (M:L:Py). The equilibrium time is 10 min for extraction of cobalt(III) from organic phase. The absorbance of coloured organic layer in chloroform is measured spectrophotometrically at 490 nm against reagent blank. The Beer's law was obeyed in the concentration range 2.5-15 ?g mL -1 of cobalt(II) and optimum concentration range was 5-12.5 ?g mL -1 of cobalt(II) and it was evaluated from Ringbom's plot. The molar absorptivity and Sandell's sensitivity of cobalt(II)-2',4'-dinitro APTPT-pyridine complex in chloroform are 1.109 × 10 3 L mol -1 cm -1 and 0.053 ?g cm -2, respectively while molar absorptivity and Sandell's sensitivity of cobalt(II)-2',4'-dinitro APTPT complex in chloroform are 6.22 × 10 2 L mol -1 cm -1 and 0.096 ?g cm -2, respectively. The composition of cobalt(II)-2',4'-dinitro APTPT-pyridine complex (1:2:2) was established by slope ratio method, mole ratio method and Job's method of continuous variation. The ternary complex was stable for more than 48 h. The interfering effects of various cations and anions were also studied, and use of suitable masking agents enhances the selectivity of the method. The method is successfully applied for the determination of cobalt(II) in binary, synthetic mixtures and real samples. A repetition of the method was checked by finding relative standard deviation (R.S.D.) for n = 5 which was 0.15%. The reliability of the method is confirmed by comparison of experimental results with atomic absorption spectrophotometer.

Kamble, Ganesh S.; Ghare, Anita A.; Kolekar, Sanjay S.; Han, Sung H.; Anuse, Mansing A.

2011-12-01

254

Development of an reliable analytical method for synergistic extractive spectrophotometric determination of cobalt(II) from alloys and nano composite samples by using chromogenic chelating ligand.  

PubMed

A synergistic simple and selective spectrophotometric method was developed for the determination of cobalt(II) with 1-(2',4'-dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol [2',4'-dinitro APTPT] as a chromogenic reagent. The proposed method has been described on the basis of synergistic effective extraction of cobalt(II) in presence of pyridine at pH range 9.5-10.2, showed orange-red coloured ternary complex having molar ratio 1:2:2 (M:L:Py). The equilibrium time is 10 min for extraction of cobalt(III) from organic phase. The absorbance of coloured organic layer in chloroform is measured spectrophotometrically at 490 nm against reagent blank. The Beer's law was obeyed in the concentration range 2.5-15 ?g mL(-1) of cobalt(II) and optimum concentration range was 5-12.5 ?g mL(-1) of cobalt(II) and it was evaluated from Ringbom's plot. The molar absorptivity and Sandell's sensitivity of cobalt(II)-2',4'-dinitro APTPT-pyridine complex in chloroform are 1.109×10(3) L mol(-1) cm(-1) and 0.053 ?g cm(-2), respectively while molar absorptivity and Sandell's sensitivity of cobalt(II)-2',4'-dinitro APTPT complex in chloroform are 6.22×10(2) L mol(-1) cm(-1) and 0.096 ?g cm(-2), respectively. The composition of cobalt(II)-2',4'-dinitro APTPT-pyridine complex (1:2:2) was established by slope ratio method, mole ratio method and Job's method of continuous variation. The ternary complex was stable for more than 48 h. The interfering effects of various cations and anions were also studied, and use of suitable masking agents enhances the selectivity of the method. The method is successfully applied for the determination of cobalt(II) in binary, synthetic mixtures and real samples. A repetition of the method was checked by finding relative standard deviation (R.S.D.) for n=5 which was 0.15%. The reliability of the method is confirmed by comparison of experimental results with atomic absorption spectrophotometer. PMID:21978559

Kamble, Ganesh S; Ghare, Anita A; Kolekar, Sanjay S; Han, Sung H; Anuse, Mansing A

2011-09-16

255

RAPID AND SENSITIVE DETERMINATION OF AMILORIDE BY CATION EXCHANGE PRECONCENTRATION AND DIRECT SOLIDPHASE UV DETECTION  

Microsoft Academic Search

A rapid, sensitive and simple spectrophotometric method for the determination of amiloride in pharmaceutical preparation and urine is described in this paper. The method is based on the sorption of amiloride on a cation-exchange resin (Sephadex SP C-25) at pH 4.0 and the direct measurement of its intrinsic UV absorbance in the solid phase at 362 nm (the maximum absorption wavelength)

P. Ortega-Barrales; G. Pellerano; F. A. Vazquez; A. Molina-Díaz

2002-01-01

256

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

257

Novel Spectrophotometric Method for the Quantitation of Urinary Xanthurenic Acid and Its Application in Identifying Individuals with Hyperhomocysteinemia Associated with Vitamin B6 Deficiency  

PubMed Central

A novel spectrophotometric method for the quantification of urinary xanthurenic acid (XA) is described. The direct acid ferric reduction (DAFR) procedure was used to quantify XA after it was purified by a solid-phase extraction column. The linearity of proposed method extends from 2.5 to 100.0?mg/L. The method is precise, yielding day-to-day CVs for two pooled controls of 3.5% and 4.6%, respectively. Correlation studies with an established HPLC method and a fluorometric procedure showed correlation coefficients of 0.98 and 0.98, respectively. Interference from various urinary metabolites was insignificant. In a small-scale screening of elderly conducted at Penghu county in Taiwan (n = 80), we were able to identify a group of twenty individuals having hyperhomocysteinemia (>15??mole/L). Three of them were found to be positive for XA as analyzed by the proposed method, which correlated excellently with the results of the activation coefficient method for RBC's AST/B6 functional test. These data confirm the usefulness of the proposed method for identifying urinary XA as an indicator of vitamin B6 deficiency-associated hyperhomocysteinemic condition.

Chen, Chi-Fen; Liu, Tsan-Zon; Lan, Wu-Hsiang; Wu, Li-An; Tsai, Chin-Hung; Chiou, Jeng-Fong; Tsai, Li-Yu

2013-01-01

258

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

259

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

PubMed

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 C(60)(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 (? = 565 nm) induced more severe damage than medium- and larger-size QDs that emitted longer-wavelength fluorescence (? = 605 and 705 nm, respectively). The fullerene derivative and TiO(2) 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. PMID:21614347

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

2011-05-25

260

A simple, inexpensive, and precise spectrophotometric method for evaluating the concentration of ascorbic acid in CSF samples: data from different neurological pathologies.  

PubMed

A method is presented for evaluating the concentration of ascorbic acid in 10 microliters samples of cerebrospinal fluid (CSF) with just ultraviolet (UV) scanning in the 220-300 nm range. The method assumes that the two main UV absorbing CSF components are proteins (with a peak at 280 nm) and ascorbic acid (with a peak at 264 nm). On this basis, the absorbances at those wavelengths are the starting points for a calculation that evaluates the sheer contribution of ascorbic acid to the absorbance at 264 nm. The rapidity of the UV analysis (just a few min), together with the precaution of keeping the samples under argon, along the short preparatory procedure, is especially suitable in the analysis of an air labile substance, such as ascorbic acid. The results of the UV procedure have been checked with parallel HPLC determinations for 19 test CSF samples and the results have shown an excellent correspondence. Finally, data are presented about the evaluation of ascorbic acid concentrations in CSF samples from various neurological pathologies in comparison with normal cases. These data show the interesting result of a significant reduction in the average ascorbic acid CSF level in patients suffering from Alzheimer's disease. However, a decrease in that parameter is found also for a few other pathologies. PMID:12625193

Cupello, A; Rapallino, M V; Tabaton, M; Lunardi, G L

2002-11-01

261

A simplified UV spectrometric method for determination of peroxide value in thermally oxidized canola oil.  

PubMed

The aim of present study was to develop a simple method on UV spectrometer for the determination of peroxide value (PV) of the frying oil. The basis of the PV determination was the stoichiometric reaction of triphenylphosphine (TPP) with the hydroperoxides present in frying oil to produce triphenylphosphine oxide (TPPO), which exhibits a readily measurable absorption band at 240 nm by ultraviolet region. The PV ranged between 0.15 and 11.66 meq. of active oxygen per kilogram of oil as the canola oil was heated from 0 to 12h in the fryer at 180 degrees C. The proposed method was correlated with official AOCS titration method and best correlation coefficient (R(2)=0.99525) was achieved, proving that there is no significant difference in the results. Therefore, developed method could serve as an alternative to the titration method, for the determination of PV in frying oils. PMID:20152417

Talpur, M Younis; Sherazi, S T H; Mahesar, S A; Bhutto, Aijaz A

2009-10-23

262

New Validated Methods for the Simultaneous Determination of Two Multicomponent Mixtures Containing Guaiphenesin in Syrup by HPLC and Chemometrics?Assisted UV?Spectroscopy  

Microsoft Academic Search

High pressure liquid chromatographic (HPLC) and spectrophotometric methods are developed for the determination of two multicomponent mixtures containing guaiphenesin, dextromethorphane hydrobromide, and sodium benzoate together with either phenylephrine hydrochloride, chlorpheniramine maleate, and butylparaben (mixture 1) or ephedrine hydrochloride and diphenhydramine hydrochloride (mixture 2). The HPLC method depended on using an ODS column with mobile phase consisting of acetonitrile ?10 mM potassium

Samy Emara; Mostafa K. Mesbah; Ghada M. Hadad

2006-01-01

263

A very sensitive flow-injection spectrophotometric determination method for iron (II) and total iron using 2', 3, 4', 5, 7-pentahydroxyflavone.  

PubMed

In this study, an ultra-sensitive and highly selective, rapid flow-injection spectrophotometric method for the determination of iron (II) and total iron has been proposed. The method was based on the reaction between iron (II) and 2', 3, 4', 5, 7-pentahydroxyflavone in slightly acidic solution with a strong absorption at 415 nm. The carrier solution used was 1?×?10(-5) M 2', 3, 4', 5, 7-pentahydroxyflavone in 0.1 M HAc/Ac(-) buffer solution at pH 4.5. Parameters that affect simultaneously the determination of iron (II) and interfering ions were tested. The relative standard deviation for the determination of 50 ?g L(-1) iron (II) was 0.85 % (n?=?10), and the limit of detection (blank signal plus three times the standard deviation of the blank) was 3 ?g L(-1), both based on injection volumes of 20 ?L. The method has been successfully applied to the determination of iron (II) and total iron in water samples and ore samples. The method was verified by analysing a certified reference material Zn/Al/Cu 43XZ3F. PMID:22628104

Asan, Adem; Aydin, Rukiye; Semiz, Deniz Karsli; Erci, Vildan; Isildak, Ibrahim

2012-05-25

264

Simultaneous determination of caffeine, 8-chlorotheophylline, and chlorphenoxamine hydrochloride in ternary mixtures by ratio-spectra zero-crossing first-derivative spectrophotometric and chemometric methods.  

PubMed

A ratio-spectra zero-crossing first-derivative spectrophotometric method and 2 chemometric methods have been used for the simultaneous determination of ternary mixtures of caffeine (A), 8-chlorotheophylline (B), and chlorphenoxamine hydrochloride (C) in bulk powder and dosage forms. In the ratio-spectra zero-crossing first-derivative spectrophotometric technique (1DD), calibration curves were linear in the range of 4-20 microg/mL for A, B, and C (r = 0.9992, 0.9994, and 0.9976, respectively). The measurements were carried out at 212, 209.2, and 231.4 nm for A, B, and C, respectively. The detection limits for A, B, and C were calculated to be 0.24, 0.34, and 0.13 microg/mL, and the percentage recoveries were 99.1 +/- 0.89, 100.1 +/- 0.95, and 100.1 +/- 1.0, respectively. Two chemometric methods, namely, the partial least-squares (PLS) model and the principal component regression (PCR) model, were also used for the simultaneous determination of the 3 drugs in the ternary mixture. A training set consisting of 15 mixtures containing different ratios of A, B, and C was used. The concentration used for the construction of the PLS and PCR models varied between 4 and 25 microg/mL for each drug. These models were used after their validation for the prediction of the concentrations of A, B, and C in mixtures. The detection limits for A, B, and C were calculated to be 0.13, 0.15, and 0.14 microg/mL, respectively, and the percent recoveries were found to be 99.8 micro 0.96, 99.9 micro 0.94, and 99.9 micro 1.18, respectively, for both methods. The 3 proposed procedures are rapid, simple, sensitive, and accurate. No preliminary separation steps or resolution equations are required; thus, they can be applied to the simultaneous determination of the 3 drugs in commercial tablets and suppositories or in quality-control laboratories. PMID:16152931

Kelani, Khadiga M

265

Systematic comparisons of various spectrophotometric and colorimetric methods to measure concentrations of protein, peptide and amino acid: detectable limits, linear dynamic ranges, interferences, practicality and unit costs.  

PubMed

There is limited and inconclusive information regarding detectable limits and linear dynamic ranges of various quantitative protein assays. We thus performed systematic comparisons of seven commonly used methods, including direct spectrophotometric quantitation at ?205 and ?280 nm (A205 and A280, respectively), bicinchoninic acid (BCA), Biuret, Bradford, Lowry and Ninhydrin methods. Purified BSA, porcine kidney extract, tryptic digested peptides derived from purified BSA, and glycine, were used as representative purified protein, complex protein mixture, peptide and amino acid, respectively. Bradford method was the most sensitive assay (LOD=0.006 mg/ml) and had the widest range of detectability (LOD-UOD=0.006-100mg/ml) for purified protein and complex protein mixture. For peptide, A205, A280, Lowry and Ninhydrin methods had a comparable LOD (0.006 mg/ml), but Ninhydrin method had the widest detectability range (LOD-UOD=0.006-100mg/ml). For amino acid, A205 and Ninhydrin methods had a comparable LOD (0.006 mg/ml), but A205 had a wider detectability range (LOD-UOD=0.006-6.250 mg/ml). Biuret method offered the widest linear dynamic range for purified protein and complex protein mixture (0.391-100mg/ml), A280 offered the widest linear dynamic range for peptide (0.024-6.250 mg/ml), and Ninhydrin method offered the widest linear dynamic range for amino acid (0.024-0.195 mg/ml). Both Laemmli's and 2-D lysis buffers had dramatic interfering effects on all assays. Concerning the practicality and unit costs, A205 and A280 were the most favorable. Among the colorimetric methods, Bradford method consumed the least amount of samples and shortest analytical time with the lowest unit cost. These are the most extensive comparative data of commonly used quantitative protein assays that will be useful for selecting the most suitable method for each study. PMID:22939137

Chutipongtanate, Somchai; Watcharatanyatip, Kamolwan; Homvises, Teerada; Jaturongkakul, Kewalee; Thongboonkerd, Visith

2012-06-30

266

A spectrophotometric biochemical oxygen demand determination method using 2,6-dichlorophenolindophenol as the redox color indicator and the eukaryote Saccharomyces cerevisiae.  

PubMed

A method to determine the spectrophotometric biochemical oxygen demand (BOD(sp)) was studied with high sensitivity and reproducibility by employing 2,6-dichlorophenolindophenol (DCIP) as a redox color indicator, the yeast Saccharomyces cerevisiae, and a temperature-controlling system providing a three-consecutive-stir unit. The absorbance of DCIP decreased due to the metabolism of organic substances in aqueous samples by S. cerevisiae. Under optimum conditions, a calibration curve for glucose glutamic acid concentration between 1.1 and 22mg O(2) L(-1) (r=0.988, six points, n=3) was obtained when the incubation mixture was incubated for 10min at 30 degrees C. The reproducibility of the optical responses in the calibration curve was 1.77% (average of relative standard deviations; RSD(av)). Subsequently, the characterization of this method was studied. The optical responses to pure organic substances and the influence of chloride ions, artificial seawater, and heavy metal ions on the sensor response were investigated before use with real samples. Measurements of real samples using river water were performed and compared with those obtained using the BOD(5) method. Finally, stable responses were obtained for 36 days when the yeast cell suspension was stored at 4 degrees C (response reduction, 89%; RSD(av) value for 9 testing days, 8.4%). PMID:17716613

Nakamura, Hideaki; Kobayashi, Shun; Hirata, Yu; Suzuki, Kyota; Mogi, Yotaro; Karube, Isao

2007-06-27

267

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

PubMed

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 mug mL(-1) and 0.058-3.285 mug 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

268

Simultaneous Determination of Potassium Clavulanate and Amoxicillin Trihydrate in Bulk, Pharmaceutical Formulations and in Human Urine Samples by UV Spectrophotometry  

PubMed Central

A simple and sensitive UV spectrophotometric method was developed and validated for the simultaneous determination of Potassium Clavulanate (PC) and Amoxicillin Trihydrate (AT) in bulk, pharmaceutical formulations and in human urine samples. The method was linear in the range of 0.2–8.5 ?g/ml for PC and 6.4–33.6 ?g/ml for AT. The absorbance was measured at 205 and 271 nm for PC and AT respectively. 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 four PC and AT 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.

Gujral, Rajinder Singh; Haque, Sk Manirul

2010-01-01

269

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

270

Comparison among the methods for hydrogen peroxide measurements to evaluate advanced oxidation processes: Application of a spectrophotometric method using copper(II) ion and 2,9-dimethyl-1,10-phenanthroline  

SciTech Connect

Hydrogen peroxide (H{sub 2}O{sub 2}) in the range of several tens to several hundreds of micromoles per liter is usually added to the process water in advanced oxidation processes (AOPs). In this study, a spectrophotometric method using copper(II) ion and 2,9-dimethyl-1, 10-phenanthroline (DMP) for measuring H{sub 2}O{sub 2} concentration was compared with other methods [i.e., spectrophotometric methods using titanium oxalate and N,N-diethyl-p-phenylenediamine (DPD) and a fluorometric method using p-hydroxyphenyl acetic acid (POHPAA)]. Particular attention was paid to sensitivities and effects of coexisting substances. The most sensitive method was the fluorometric method, followed in order by DPD, DMP, and the titanium oxalate colorimetric method; their detection limits in 1-cm cells were 0.16, 0.77, 0.80, and 29 {micro}M, respectively. Therefore, the DMP method was found to be reasonably sensitive when applied to AOPs. In the DMP method, copper(II)-DMP complexes react with humic acid, and colored chemicals are produced. However, the slopes of the calibration curves of H{sub 2}O{sub 2} containing up to 10 mg of C L{sup {minus}1} from humic acid did not change significantly as compared to that in ultrapure water. The effect of chlorine on the DMP method was not observed up to at least 23 {micro}M (0.8 mg of Cl L{sup {minus}1}) of free chlorine, although the DPD and fluorometric methods are known to be interfered by chlorine. From this study, it was concluded that the DMP method is suitable to be used in AOPs.

Kosaka, Koji; Yamada, Harumi; Matsui, Saburo [Kyoto Univ., Otsu City, Shiga (Japan). Research Center for Environmental Quality Control; Echigo, Shinya [Univ. of Illinois, Urbana, IL (United States). Dept. of Civil Engineering; Shishida, Kenichi [Takuma Co. Ltd., Amagasaki, Hyogo (Japan). Sewerage Engineering Dept.

1998-12-01

271

Direct Spectrophotometric Assay for Benzaldehyde Lyase Activity  

PubMed Central

Benzaldehyde lyase from Pseudomonas fluorescens Biovar I. (BAL, EC 4.1.2.38) is a versatile catalyst for the organic synthesis of chiral ?-hydroxy ketones. To allow fast assessment of enzyme activity, a direct spectrophotometric assay is desirable. Here, a new robust and easy-to-handle assay based on UV absorption is presented. The assay developed is based on the ligation of the ?-hydroxy ketone (R)-2,2?-furoin from 2-furaldehyde. A robust assay with direct monitoring of the product is facilitated with a convenient concentration working range minimising experimental associated with low concentrations.

Natalia, Dessy; Kohlmann, Christina; Ansorge-Schumacher, Marion B.; Greiner, Lasse

2011-01-01

272

Determination of meloxicam in human plasma using a HPLC method with UV detection and its application to a pharmacokinetic study  

Microsoft Academic Search

A simple and sensitive high performance liquid chromatography method using UV detection (HPLC-UV) for the determination of meloxicam in human plasma was developed and validated. After extraction with diethyl ether, the chromatographic separation of meloxicam was carried out using a reverse phase Sunfire C18 column (150mm×4.6mm, 5?m) with a mobile phase of acetonitrile–20mM potassium hydrogen phosphate (40:60, v\\/v, pH 3.5)

Jung-Woo Bae; Mi-Jeong Kim; Choon-Gon Jang; Seok-Yong Lee

2007-01-01

273

Automatic corellation method to estimate wind velocity from UV images of Venus on VMC data  

NASA Astrophysics Data System (ADS)

The horizontal components of wind velocity vectors of the Venus upper clouds are estimated from the UV images obtained by the Venus Monitoring Camera on the Venus Express spacecraft. Two images obtained at different moments provide information about motion of cloud layer regions. The motion of each region is evaluated by means of correlations. The method includes: -creation of longitude-latitude grid -computation of intensity for every node of the grid by using a three-point interpolation -computation of correlation coefficients -analysis of the correlation function -elimination of wrong results -computation of zonal and meridional velocity -computation of averaged profiles The obtained profiles are compared with results obtained by means of a visual method.

Patsaeva, Marina; Khatuntsev, Igor; Titov, Dmitri; Markiewicz, Wojciech; Ignatiev, Nikolay

274

Two localized CO2 laser treatment methods for mitigation of UV damage growth in fused silica  

NASA Astrophysics Data System (ADS)

Two methods: high-power, short-time, single-shot irradiation (Method A) and low-power, long-time, multi-shot irradiation (Method B) are investigated to mitigate the UV damage growth in fused silica by using a 10.6-?m CO2 laser. To verify the mitigation effect of the two methods, the laser induced damage thresholds (LIDTs) of the mitigated sites are tested with a 355-nm, 6.4-ns Nd:YAG laser, and the light modulation of the mitigation sites are tested with a 351-nm continuous Nd:YLF laser. The mitigated damaged sites treated with the two methods have almost the same LIDTs, which can recover to the level of pristine material. Compared with Method A, Method B produces mitigated sites with low crater depth and weak light modulation. In addition, there is no raised rim or re-deposited debris formed around the crater edge for Method B. Theoretical calculation is utilized to evaluate the central temperature of the CO2 laser beam irradiated zone and the radius of the crater. It is indicated that the calculated results are consistent with the experimental results.

Jiang, Yong; Xiang, Xia; Liu, Chun-Ming; Luo, Cheng-Si; Wang, Hai-Jun; Yuan, Xiao-Dong; He, Shao-Bo; Ren, Wei; Lü, Hai-Bing; Zheng, Wan-Guo; Zu, Xiao-Tao

2012-06-01

275

UV differential optical absorption method for measuring sulfur content in coal  

NASA Astrophysics Data System (ADS)

Determining the sulfur content in coal rapidly and accurately can provide a technical basis for the enterprises and the environmental administration departments. A novel method for measuring the sulfur content in coal based on UV differential optical absorption is presented in this paper. However, compared with the applications in atmosphere monitoring, the UV differential optical absorption spectroscopy (DOAS) for the sulfur content measurement in coal has the problems that the concentration range of SO2 in the flue gas is wider and the optical path-length of the gas cell is shorter. To solve these problems, an improved DOAS algorithm based on a finite impulse response (FIR) filter and a nonlinear compensation technique is proposed. An experimental measurement system based on the modified DOAS is designed and established. The standard SO2 gas and five kinds of standard coals are experimentally tested. Theoretical and experimental results show that the lower detection limit of the system is better than 0.014%, and the repeatability of the measurement system fairly meets the national standard of China. The system has advantages of low maintenance and shorter measurement duration (4 min).

Song, Feihu; Xu, Chuanlong; Wang, Shimin

2012-02-01

276

A novel method to calculate solar UV exposure relevant to vitamin D production in humans.  

PubMed

We present a novel method to calculate vitamin D3 -weighted exposure by integrating the incident solar spectral radiance over all relevant parts of the human body. Earlier investigations are based on the irradiance on surfaces, whereas our calculated exposure of a voxel model of a human takes into account the complex geometry of the radiation field. Assuming that sufficient vitamin D3 (1000 international units) can be produced within the human body in one minute for a completely uncovered body in vertical posture in summer at midlatitudes (e.g. Rome, June 21, noon, UV index of 10), we calculate the exposure times needed in other situations or seasons to gain enough vitamin D3 . Our calculations show that the UV index is not a good indicator for the exposure which depends on the orientation of the body (e.g. vertical (standing) or horizontal (lying down) posture). Without clothing the exposure is dominated by diffuse sky radiation and it is nearly irrelevant how the body in vertical posture is oriented toward the sun. At the winter solstice (December 21, noon, cloudy) at least in central Europe sufficient vitamin D3 cannot be obtained with realistic clothing, even if the exposure were extended to all daylight hours. PMID:23517086

Seckmeyer, Gunther; Schrempf, Michael; Wieczorek, Anna; Riechelmann, Stefan; Graw, Kathrin; Seckmeyer, Stefan; Zankl, Maria

2013-05-27

277

Measurements of label free protein concentration and conformational changes using a microfluidic UV-LED method.  

PubMed

This paper presents a microchip-based system for measuring concentrations and dynamic conformational changes in proteins without any use of extrinsic fluorescent labeling. The microchannel flow of protein molecules was integrated with an ultraviolet light-emitting diode (UV-LED, lambda ex = 295 nm) and a photodetector (lambda em = 330 nm). The intrinsic fluorescence shift, arising from selectively exciting aromatic amino acid tryptophan (Trp), was monitored to quantify refolding pathways by dynamically varying the concentration of the chemical denaturant, urea. Short diffusion distances in the microchannel result in rapid equilibrium between protein and titrating solutions. Dilutions on the chip were tightly regulated using pressure controls, rather than syringe-based flow, as verified with extensive on-chip tracer dye controls. The concentrations of proteins were first measured using the UV-LED microfluidic platform, and the data showed detection limits down to 72, 128, and 250 nM for tryptophan, bovine serum albumin (BSA), and bovine carbonic anhydrase (BCA), respectively. To validate the protein assay method, folding transition experiments were performed using a well-characterized protein, BSA. The microchip protein refolding transitions using intrinsic fluorescence were well-correlated with conventional fluorometer experiments. The microfluidic platform facilitates refolding studies to identify rapidly the optimal folding strategy for a protein using small quantities of material. The technique offers a real alternative to bulky microfluidic systems consisting of large and expensive laser-based designs. PMID:17994758

Lee, Jinkee; Tripathi, Anubhav

2007-11-10

278

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

279

Inhibitory effect of unheated and heated d-glucose, d-fructose and l-cysteine solutions and Maillard reaction product model systems on polyphenoloxidase from apple. I. Enzymatic browning and enzyme activity inhibition using spectrophotometric and polarographic methods  

Microsoft Academic Search

To demonstrate whether caramelization products (CP) and Maillard reaction products (MRP) could inhibit enzymatic browning and\\/or inactivate apple polyphenoloxidase (PPO), l-cysteine, d-glucose, d-fructose aqueous solutions and equimolar mixtures (1 M) of hexose\\/cysteine were each tested on purified enzyme activity, using both spectrophotometric and polarographic methods. Inhibition was evaluated as a function of temperature (80–110 °C), time (0–48 h) of heating and

Catherine Billaud; Emeline Roux; Sophie Brun-Mérimee; Christelle Maraschin; Jacques Nicolas

2003-01-01

280

Selective and sensitive extraction spectrophotometric method for the determination of vanadium (V) as a mixed ligand complex with N -phenyl benzohydroxamic acid and 4-(2-pyridylazo)resorcinol in non-aqueous media  

Microsoft Academic Search

A selective, sensitive and direct method for the spectrophotometric determination of vanadium in steels is developed in which vanadium is extracted withN-phenyl benzohydroxamic acid (PBHA) into chloroform from 5M hydrochloric acid medium followed by colour development by addition of 4-(2-pyridylazo)resorcinol (PAR) inN,N-dimethyl formamide (DMF). The vanadium(V)-PBHA-PAR mixed ligand complex shows maximum absorbance at 560 nm with a molar absorptivity 3.6

Yerramilli Anjaneyulu; Manda R. P. Reddy; Patti V. S. Kumar; Chandra S. Kavipurapu; Bevara V. Rao

1990-01-01

281

Spectrophotometric Determination of Uranium in Nuclear Waste.  

National Technical Information Service (NTIS)

A spectrophotometric method for determining uranium in nuclear waste was developed using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (bromo-PADAP). By extracting the color into Aliquat-336 it was possible to accurately measure U at the 1 mu g level. No ...

W. I. Winters

1976-01-01

282

Separation and spectrophotometric determination of elements  

Microsoft Academic Search

This book is a useful text intended as a reference for the laboratory that is either involved in spectrophotometric analysis or requires separations prior to analysis by any method. It attempts to cover a diverse series of topics in fewer than 700 pages. Part I of the book covers general topics such as separation schemes (solvent extraction, precipitation, volatility, ion

Marczenko

1986-01-01

283

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

2011-09-27

284

Development and validation of spectrophotometric methods for simultaneous estimation of citicoline and piracetam in tablet dosage form  

PubMed Central

Context: Citicoline (CN) and piracetam (PM) combination in tablet formulation is newly introduced in market. It is necessary to develop suitable quality control methods for rapid and accurate determination of these drugs. Aim: The study aimed to develop the methods for simultaneous determination of CN and PM in combined dosage form. Materials and Methods: The first method was developed by formation and solving simultaneous equations using 280.3 and 264.1 nm as two analytical wavelengths. Second method was absorbance ratio in which wavelengths selected were 256.6 nm as its absorptive point and 280.3 nm as ?max of CN. According to International Conference on Harmonization (ICH) norm, the parameters – linearity, precision, and accuracy were studied. The methods were validated statistically and by recovery studies. Results: Both the drugs obeyed Beer-Lambert's law at the selected wavelengths in concentration range of 5-13 ?g/ml for CN and 10-22 ?g/ml for PM. The percentage of CN and PM in marketed tablet formulation was found to be 99.006 ± 0.173 and 99.257 ± 0.613, respectively; by simultaneous equation method. For Q-Absorption ratio method the percentage of CN and PM was found to be 99.078 ± 0.158 and 99.708 ± 0.838, respectively. Conclusions: The proposed methods were simple, reproducible, precise and robust. The methods can be successfully applied for routine analysis of tablets.

Sivadas, Akhila; Sathi, Aiswarya; Sathi, Kavya; Rahate, Kalpana Pravin

2013-01-01

285

Second derivative spectrophotometric method for simultaneous determination of cobalt, nickel and iron using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol.  

PubMed

A simple, sensitive and rapid derivative spectrophotometric method using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) has been developed for simultaneous determination of Co(II), Ni(II) and Fe(II) which have very similar chemical behavior and appear together in many real samples. The complexes of all these metal ions with 5-Br-PADAP were formed immediately at pH 7.0 ammonium acetate buffered solution and were stable for at least 24h. Second derivative spectra were selected for evaluation, because working wavelength determination was more precise and spectral overlap was less than in the ordinary and first derivative spectra. Three wavelengths at which the complexes exhibit extremum (2)D values for Co(II), Ni(II) and Fe(II) were selected as analytical wavelengths, i.e., 640, 600 and 740nm, respectively. Calibration curves drawn with zero-to-peak values at mentioned wavelengths were linear between 80 and 2000ngml(-1) for each metal ion. Concentrations of Co(II) and Ni(II) were calculated from the total (2)D values and the sum of the linear equations for these three cations at 640 and 600nm, after Fe(II) assay by making use of the (2)D value at 740nm. Limits of detection (LOD) for Co(II), Ni(II) and Fe(II) were 2.7, 13.9 and 3.0ngml(-1), respectively. The method has been applied to tool steel and heater resistance wire samples successfully. PMID:18969387

Sözgen, Kevser; Tütem, Esma

2004-04-19

286

Determination and resolution of non-UV–visible absorptive component during a kinetic process with modified soft modeling methods  

Microsoft Academic Search

Soft modeling (SM) methods can be used to resolve spectroscopic data from complicated reaction processes with unknown kinetics, with the exception of data containing a component for which there is no spectroscopic information available, such as an intermediate that does not absorb in the UV–visible region. In this work, modified SM methods were developed to resolve these undetectable components. Based

Qinghua Zhang; Xinwei Feng; Dejun Zhang; Yi Zhao; Zhongliang Zhu

2011-01-01

287

New RP?HPLC Method with UV?Detection for the Determination of Carvedilol in Human Serum  

Microsoft Academic Search

Carvedilol has been used as an antihypertensive drug and also possesses antioxidant and antiproliferative effects. A simple and sensitive analytical method for carvedilol in human serum by using high performance liquid chromatography (HPLC) was developed. The method employs a liquid?liquid extraction for isolation and sample concentration followed by reversed phase liquid chromatography (RPLC) analysis using ultraviolet (UV) detection at 238 nm.

Ramesh Gannu; Vamshi Vishnu Yamsani; Yamsani Madhusudan Rao

2007-01-01

288

Surface Uv Flux Estimation From Gome In Antarctica Using Different Ozone Column Retrieval Methods  

Microsoft Academic Search

Surface UV flux estimation from Global Ozone Monitoring Experiment (GOME) measurements especially requires knowledge of solar elevation, cloud condition, and total column amount of ozone. In particular over snow and ice covered areas like Antarctica, the detection of clouds and the estimation of their effects on UV radiance from reflectivity measurements in ultraviolet\\/visible spectral range is uncertain. Cur- rent operational

M. Coldewey-Egbers; M. Weber; M. Buchwitz; J. P. Burrows

2002-01-01

289

TLC-UV densitometric and GC-MSD methods for simultaneous quantification of morphine and codeine in poppy capsules  

Microsoft Academic Search

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

Daniela-Saveta Popa; R Oprean; Elena Curea; N Preda

1998-01-01

290

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

291

Determination of total content of phenolic compounds and their antioxidant activity in vegetables--evaluation of spectrophotometric methods.  

PubMed

This research studies in detail the contents of phenolic compounds determined by the Folin-Ciocalteu reagent and the antioxidant activities determined by the TEAC (Trolox equivalent antioxidant capacity), DPPH (using diphenyl-p-picrylhydrazyl radical), and FRAP (ferric reducing antioxidant power) methods, and their correlations for used standards with these methods (catechine, gallic acid, caffeic acid, ferulic acid, Trolox, ascorbic acid, and ferrous sulfate) and extracts from several species of commonly consumed vegetables were studied in detail. The comparison of absolute values of absorption coefficients for used standards and for individual methods allows one to choose optimal common standards for methods to be compared. The procedures applied for the same sets of the extracts using identical calibration procedures and common standards allowed better comparison of the results obtained by the TEAC, DPPH, and FRAP methods. The values of content of phenolic substances and total antioxidant activity of the sets of samples correlate very well for all used methods. The very high values of antioxidant activity were found in intensely colored vegetables (red cabbage, red onion, etc.), and the values were very low in watery vegetables such as potato, marrow, and cucumber. PMID:16448157

Stratil, Pavel; Klejdus, Borivoj; Kubán, Vlastimil

2006-02-01

292

Quantitative methods for structural characterization of proteins based on deep UV resonance Raman spectroscopy.  

PubMed

Here we report on novel quantitative approaches for protein structural characterization using deep UV resonance Raman (DUVRR) spectroscopy. Specifically, we propose a new method combining hydrogen-deuterium (HD) exchange and Bayesian source separation for extracting the DUVRR signatures of various structural elements of aggregated proteins including the cross-beta core and unordered parts of amyloid fibrils. The proposed method is demonstrated using the set of DUVRR spectra of hen egg white lysozyme acquired at various stages of HD exchange. Prior information about the concentration matrix and the spectral features of the individual components was incorporated into the Bayesian equation to eliminate the ill-conditioning of the problem caused by 100% correlation of the concentration profiles of protonated and deuterated species. Secondary structure fractions obtained by partial least squares (PLS) and least squares support vector machines (LS-SVMs) were used as the initial guess for the Bayessian source separation. Advantages of the PLS and LS-SVMs methods over the classical least squares calibration (CLSC) are discussed and illustrated using the DUVRR data of the prion protein in its native and aggregated forms. PMID:20580825

Shashilov, Victor A; Sikirzhytski, Vitali; Popova, Ludmila A; Lednev, Igor K

2010-05-24

293

Quantitative HPLC-UV method for the determination of firocoxib from horse and dog plasma.  

PubMed

A sensitive reversed-phase HPLC-UV method was developed for the determination of firocoxib, a novel and highly selective COX-2 inhibitor, in plasma. A 1.0 mL dog or horse plasma sample is mixed with water and passed through a hydrophobic-lipophilic copolymer solid-phase extraction column to isolate firocoxib. Quantitation is based on an external standard curve. The method has a validated limit of quantitation of 25 ng/mL and a limit of detection of 10 ng/mL. The validated upper limit of quantitation was 2500 ng/mL for horses and 10,000 ng/mL for dogs. The average recoveries ranged from 88-93% for horse plasma and 96-103% for dog plasma. The coefficient of variation in all cases was less than 10%. This method is suitable for the analysis of clinical samples from pharmacokinetic and bioequivalence studies and drug monitoring. PMID:17537684

Kvaternick, Valerie; Malinski, Thomas; Wortmann, Jill; Fischer, James

2007-05-10

294

Comparison of Spectrophotometric and Visual Readings of NCCLS Method and Evaluation of a Colorimetric Method Based on Reduction of a Soluble Tetrazolium Salt, 2,3Bis {2Methoxy4Nitro5-[(Sulfenylamino) Carbonyl]-2H- Tetrazolium-Hydroxide}, for Antifungal Susceptibility Testing of Aspergillus Species  

Microsoft Academic Search

The susceptibilities of 25 clinical isolates of various Aspergillus species (Aspergillus fumigatus, A. flavus, A. terreus, A. ustus, and A. nidulans) to itraconazole (ITC) and amphotericin B (AMB) were determined using the standard proposed by NCCLS for antifungal susceptibility testing of filamentous fungi, a modification of this method using spectrophotometric readings, and a colorimetric method using the tetrazolium salt 2,3-bis

JOSEPH MELETIADIS; JOHAN W. MOUTON; JACQUES F. G. M. MEIS; BIANCA A. BOUMAN; PETER J. DONNELLY; PAUL E. VERWEIJ

2001-01-01

295

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...

296

[The experience with spectrophotometric method for determination of teeth colour changes in the process of tooth whitening by different systems].  

PubMed

The use of spectrophotometer VITA Easyshade is described as an objective method of definition of color of a teeth alongside with a standard scale VITA. Results of assessment of efficiency, safety, a comparative estimation of domestic bleaching Aquafresh and LumaArch systems are given. PMID:17310941

Porkhun, T V; Iakoviuk, I A

2006-01-01

297

A rapid spectrophotometric method for the determination of trace level lead using 1,5-diphenylthiocarbazone in aqueous micellar solutions.  

PubMed

A very simple, ultra-sensitive and fairly selective direct spectrophotmetric method is presented for the rapid determination of lead(II) at ultra-trace level using 1,5-diphenylthiocarbazone (dithizone) in micellar media. The presence of the micellar system avoids the previous steps of solvent extraction and reduces the cost and toxicity while enhancing the sensitivity, selectivity and the molar absorptivity. The molar absorptivities of the lead-dithizone complex formed in the presence of the cationic cetyltrimethylammonium bromide (CTAB) surfactants are almost ten times the value observed in the standard method, resulting in an increase in the sensitivity of the method. The reaction is instantaneous and the absorbance remains stable for over 24 h. The average molar absorption coefficient was found to be 3.99 x 10(5) L mol(-1) cm(-1) and Sandell's sensitivity was 30 ng cm(-2) of Pb. Linear calibration graphs were obtained for 0.06-60 mg L(-1) of Pb(II); the stoichiometric composition of the chelate is 1:2 (Pb:dithizone). The interference from over 50 cations, anions and complexing agents has been studied at 1 mg L(-1) of Pb(II). The method was successfully used in the determination of lead in several standard reference materials (alloys and steels), environmental water samples (potable and polluted), biological samples (human blood and urine), soil samples and solutions containing both lead(II) and lead(IV) and complex synthetic mixtures. The method has high precision and accuracy (sigma = +/-0.01 for 0.5 mg L(-1)). PMID:17297232

Khan, Humaira; Ahmed, M Jamaluddin; Bhanger, M Iqbal

2007-02-01

298

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

2012-06-04

299

Low-level luminescence as a method of detecting the UV influence on biological systems  

NASA Astrophysics Data System (ADS)

It is well known that low-level luminescence is correlated to many physiological and biological parameters, e.g. cell cycle, temperature, oxidation- and UV-stress. We report some new approaches on low-level luminescence measurements and UV influence on different biological systems. One example concerns yeast cultures, which show an increasing intensity of luminescence after UV-treatment with a maximum after 1.5 h. Investigations on normal human fibroblasts and keratinocytes display different longtime kinetics: The former show no changes of the luminescence in time, the latter an increase that reaches the maximum after 9 h. The time-dependent spectral measurement on xeroderma pigmentosum after UV-treatment displays a time-shift of the action-spectra shifting the maximum from 400 nm to 420 nm in 12 h. Some results on neutrophils reveals spectral UV influence on respiratory burst and the cellular repair system. The results on human skin display spectral changes of low-level luminescence after UV-treatment. These results provide a useful tool of analyzing UV influence on human skin.

Mei, Wei-Ping; Popp, Fritz A.

1995-02-01

300

Spectrophotometric determination of clozapine in pharmaceuticals  

Microsoft Academic Search

New Spectrophotometric methods for the assay of clozapine (CZP) in pure and dosage forms are described. Method A is based on the oxidative coupling reaction of CZP with 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) in the presence of ceric ammonium sulphate to form a coloured species (?max 570 nm). Method B is also based on the oxidative coupling reaction of CZP withP-,N,N-dimethylpheny-lenediamine

Chilukuri S. P. Sastry; Thuta Vijaya Rekha; Atreyapurapu Satyanarayana

1998-01-01

301

Spectrophotometric determination of some aromatic amines  

Microsoft Academic Search

A method for spectrophotometric determination of four aromatic amines is described. The method is based on the reaction between the amine and the colorless Fe(III)-ferrozine complex. The amine reduces iron from Fe(III) to Fe(II) which forms a violet colored complex with ferrozine. The method is suitable for to the determination of 1,4-phenylenediamine, 2,4-diaminotoluene, 8-aminoquinoline and 2-amino-3-hydroxypyridine. The effect of different

Nidal A Zatar; Ali Z Abu-Zuhri; Asma A Abu-Shaweesh

1998-01-01

302

The chromatomembrane method used for sample preparations in the spectrophotometric determination of zinc and copper in pharmaceuticals  

Microsoft Academic Search

The chromatomembrane cell (CMC) was used to extract zinc and copper and to preconcentrate them for their separation from pharmaceutical preparations. The method performance was evaluated at the determination of the enrichment factor, the linearity of response, the reproducibility, the accuracy and the sensitivity. In practice a five-fold enrichment has been enough provided that sample sizes of 0.825ml were introduced.

Ganden Supriyanto; Jürgen Simon

2005-01-01

303

Spectrophotometric and spectrofluorimetric investigation of different equilibria of a recently synthesized Schiff base with the aid of chemometric methods  

Microsoft Academic Search

In this study ground and excited states acidic dissociation constants of a recently synthesized Schiff base was obtained in a DMF:water mixture of 30:70 (v\\/v) using absorption and fluorescent spectra of the Schiff base in different pH values with the aid of chemometric methods. In addition, the fluorescent of the two kinds of tautomers of this Schiff base was investigated

Abbas Afkhami; Hasan Keypour; Farzad Khajavi; Majid Rezaeivala

2011-01-01

304

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).

Soomro, Rubina; Ahmed, M. Jamaluddin; Memon, Najma; Khan, Humaira

2008-01-01

305

[Quantitative analysis of protein concentration by absorption peak integration method of UV spectroscopy--taking alkaline phosphatase as an example].  

PubMed

Adsorption of alkaline phosphatase (APase) on minerals (goethite, montmorillonite) and sediments from Taihu Lake was studied. However, the concentration of alkaline phosphatase in the supernatant cannot be analyzed by the adsorption at 280 nm due to that the UV spectroscopy was changed. Quantitative analysis of alkaline phosphatase in the supernatant by the absorption peak (252-305 nm) integration method of UV spectroscopy was developed. This method determined the concentrations of alkaline phosphatase well. Compared to the results of Bradford, the absorption peak integration method can determine the concentrations of supernatant fast, conveniently, and accurately. This method can also be applied to other protein solution analysis and similar experiments. The drawbacks of traditional single wavelength method (280nm) were overcome to some extent based on the method of absorption peak integration. PMID:24059187

Zhu, Yuan-Rong; Wu, Feng-Chang; Lin, Ying

2013-07-01

306

Spectrophotometric Estimation of Nimesulide and its Formulations  

Microsoft Academic Search

Four simple and sensitive visible spectrophotometric methods (A–D) have been described for the assay of nimesulide (NMD)\\u000a either in pure form or in pharmaceutical formulations. Methods A and B are based on the oxidative coupling between the reduced\\u000a product of NMD (RNMD) and p-N,N-dimethyl phenylenediamine dihydrochloride (DMPD) in presence of chloramine – T (CAT) or 3-methyl-2-benzothiazolinone\\u000a hydrazone hydrochloride (MBTH) in

Chilukuri S. R. Lakshmi; Manda N. Reddy

1999-01-01

307

Observation of nanoparticle formation process by two-dimensional laser-induced fluorescence, UV Rayleigh scattering, and re-decomposition laser-induced fluorescence methods  

Microsoft Academic Search

We have investigated the formation process of nanoparticles in the laser ablation plume by different laser imaging spectroscopy techniques, such as Two-Dimensional laser induced fluorescence (2D-LIF), UV Rayleigh scattering (UV- RS), and Re-Decomposition LIF (ReD-LIF). Clusters, which are hardly observed by the UV-RS method due to their small size, are observed by the ReD-LIF method. The dynamics and formation processes

Junichi Muramoto; Takahiro Inmaru; Yoshiki Nakata; Tatsuo Okada; Mitsuo Maeda

2000-01-01

308

Spectrophotometric Studies on Intact Muscle  

PubMed Central

The concentrations of the components of the respiratory chain were determined in a variety of intact skeletal muscles by a method of spectrophotometric observation of the transmitted light. In the case of the toad sartorius, these measurements were checked against isolated mitochondrial suspensions prepared from toad skeletal muscles. The relative concentrations of the respiratory components were found to be in reasonable agreement with those of various mitochondrial preparations of mammalian tissues and of the ones from toad skeletal muscle. The rather low cytochrome b and pyridine nucleotide levels in the anoxic minus oxygenated difference spectra were shown to be caused to a certain degree by a partial reduction during the resting steady state. Upon treatment with a strong, reducing agent or after long anoxia some absorption bands appeared with maxima at 591, 562 to 564, and 432 to 434 mµ both in the intact and in the mitochondrial fractions of muscle tissue; they do not appear to be associated with the respiratory chain.

Jobsis, Frans F.

1963-01-01

309

Multicomponent spectrophotometric assay of riboflavine and photoproducts.  

PubMed

A multicomponent spectrophotometric method has been developed for the simultaneous determination of riboflavine, formylmethylflavine and degradation products in photolysed solutions. It is based on partial separation of the photoproducts by chloroform extraction at pH 2.0 in a potassium chloride-hydrochloric acid solution and subsequent determination, in the aqueous phase, of riboflavine and formylmethylflavine at 445 and 385 nm. The chloroform extract containing lumichrome and lumiflavine is evaporated to dryness, the residue dissolved in acetate buffer (pH 4.5) and the products determined at 356 and 445 nm. The reproducibility of the method, based on the analysis of synthetic mixtures, is within +/- 5%. Absorption corrections for minor products and interfering substances have been proposed. Chromatographic, spectrophotometric and distribution coefficient data for riboflavine and photoproducts are reported. The method is specific, rapid and convenient for photodegradation studies of riboflavine and formylmethylflavine. PMID:2094420

Ahmad, I; Rapson, H D

1990-01-01

310

Spectrophotometric determination of protein concentration.  

PubMed

This unit describes spectrophotometric and colorimetric methods for measuring the concentration of a sample protein in solution. Absorbance measured at 280 nm (A(280)) is used to calculate protein concentration by comparison with a standard curve or published absorptivity values for that protein (a(280)). Alternatively, absorbance measured at 205 nm (A(205)) is used to calculate the protein concentration. The A(280) and A(205) methods can be used to quantify total protein in crude lysates and purified or partially purified protein. A spectrofluorometer or a filter fluorometer can be used to measure the intrinsic fluorescence emission of a sample solution; this value is compared with the emissions from standard solutions to determine the sample concentration. The fluorescence emission method is used to quantify purified protein. This simple method is useful for dilute protein samples and can be completed in a short amount of time. There are two colorimetric methods: the Bradford colorimetric method, based upon binding of the dye Coomassie brilliant blue to the protein of interest, and the Lowry method, which measures colorimetric reaction of tyrosyl residues in the protein sample. PMID:20976674

Simonian, Michael H

2004-09-01

311

Spectrophotometric determination of protein concentration.  

PubMed

This unit describes spectrophotometric and colorimetric methods for measuring the concentration of a sample protein in solution. Absorbance measured at 280 nm (A(280)) is used to calculate protein concentration by comparison with a standard curve or published absorptivity values for that protein (a(280)). Alternatively, absorbance measured at 205 nm (A(205)) is used to calculate the protein concentration. The A(280) and A(205) methods can be used to quantify total protein in crude lysates and purified or partially purified protein. A spectrofluorometer or a filter fluorometer can be used to measure the intrinsic fluorescence emission of a sample solution; this value is compared with the emissions from standard solutions to determine the sample concentration. The fluorescence emission method is used to quantify purified protein. This simple method is useful for dilute protein samples and can be completed in a short amount of time. There are two colorimetric methods: the Bradford colorimetric method, based upon binding of the dye Coomassie brilliant blue to the protein of interest, and the Lowry method, which measures colorimetric reaction of tyrosyl residues in the protein sample. PMID:18228395

Simonian, Michael H

2002-08-01

312

Method for fabrication of paper-based microfluidic devices by alkylsilane self-assembling and UV/O3-patterning.  

PubMed

This work presents a novel and facile method for fabricating paper-based microfluidic devices by means of coupling of hydrophobic silane to paper fibers followed by deep UV-lithography. After filter paper being simply immersed in an octadecyltrichlorosilane (OTS) solution in n-hexane for 5 min, the hydrophilic paper became highly hydrophobic (water contact angle of about 125°) due to the hydrophobic OTS molecules were coupled to paper's cellulose fibers. The hydrophobized paper was then exposed to deep UV-lights through a quartz mask that had the pattern of the to-be-prepared channel network. Thus, the UV-exposed regions turned highly hydrophilic whereas the masked regions remained highly hydrophobic, generating hydrophilic channels, reservoirs and reaction zones that were well-defined by the hydrophobic regions. The resolution for hydrophilic channels was 233 ± 30 ?m and that for between-channel hydrophobic barrier was 137 ± 21 ?m. Contact angle measurement, X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance Fourier transform-infrared (ATR-FT-IR) spectroscopy were employed to characterize the surface chemistry of the OTS-coated and UV/O(3)-treated paper, and the related mechanism was discussed. Colorimetric assays of nitrite are demonstrated with the developed paper-based microfluidic devices. PMID:23244032

He, Qiaohong; Ma, Cuicui; Hu, Xianqiao; Chen, Hengwu

2013-01-07

313

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

314

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.  

PubMed

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. PMID:21145780

Shyla, B; Mahadevaiah; Nagendrappa, G

2010-11-23

315

Development of a highly sensitive and selective method for extractive spectrophotometric determination of aluminum(III) from environmental matrices, synthetic mixtures, and alloys using orthohydroxypropiophenoneisonicotinoylhydrazone  

Microsoft Academic Search

Orthohydroxypropiophenoneisonicotinoylhydrazone (OHPINH) is proposed as a new sensitive reagent for the spectrophotometric\\u000a determination of aluminum(III). OHPINH formed a greenish-yellow colored complex with aluminum(III) in buffer solutions of\\u000a pH 1 to 3. The color in pH 2 was stable for more than 48 h. The complex solution has given maximum absorbance at 390 nm when\\u000a the reagent was chosen as blank and the absorbance of

C. Ramachandraiah; J. Rajesh Kumar; S. Adinarayana Reddy; Jin-Young Lee; A. Varada Reddy

2010-01-01

316

DEVELOPMENT AND VALIDATION OF HPLC-UV METHOD FOR THE DETERMINATION OF CLOPIDOGREL IN PHARMACEUTICAL DOSAGE FORM AND HUMAN PLASMA  

Microsoft Academic Search

A simple, rapid, and sensitive high performance liquid chromatographic method with UV detection has been developed for the quantification of clopidogrel in human plasma and pharmaceutical dosage form using diclofenac sodium as an internal standard and validated according to standard guidelines. The separation of clopidogrel and diclofenac sodium was achieved using Hypersil BDS RP18 (250 × 4.6 mm, 5 µm) at a column oven

Muhammad. K. Javed; Zafar Iqbal; Abbas Khan; Abad Khan; Yasar Shah; Lateef Ahmad

2011-01-01

317

Wave scattering with the UV multilevel partitioning method: 1. Two-dimensional problem of perfect electric conductor surface scattering  

Microsoft Academic Search

A UV method with multilevel partitioning (UVMLP) is developed to solve electromagnetic problem. In this paper we demonstrate the technique to treat electromagnetic problem for large surface in a two-dimensional (2-D) problem. Using the multilevel partitioning (MLP), the decomposition preprocessing, and the matrix vector multiplication require CPU of O(N logN) per iteration with a smaller constant factor for matrix column

Leung Tsang; Dong Chen; Peng Xu; Qin Li; Vikram Jandhyala

2004-01-01

318

A new method of chlorophenols decomposition based on UV-irradiation by XeBr-excilamp and their subsequent biodegradation  

NASA Astrophysics Data System (ADS)

The combined decomposition method of chlorophenols (CP) is offered. The method is based on photolysis of CP through XeBr-excilamp UV irradiation at 283 nm in a flow photoreactor with subsequent treatment of photolysis products by microorganism-destructor B. cereus isolated from an aeration pond of Baikal pulp-and-paper mill. At initial concentration of CP of 20 mg/l the polluted solutions can be utilized directly by means of biological treatment using B. cereus under aerobic conditions. However, if the initial CP concentration is higher than 20 mg/l, the polluted solutions are low biodegradable. It is shown, that the combined treatment is most effective method in this case. At initial CP concentration of 50 mg/l and higher it is suggested to use the deep preliminary UV-treatment with the purpose of removal 80-90 % of initial CP. It is revealed, that 4-CP is relatively persistent compound for B. cereus, easily decomposed by UV-radiation of XeBr-excilamp. As a result of subsequent biological treatment during 10 days the utilization of basic CP photoproducts is obtained. Experimentally, the preliminary UV-processing time was essentially less than that found earlier by E. Tamer, Z. Hamid, Aly A. (Chemosphere, 2006), where the half-life periods of initial CP were from 2.2 to 54 hours at the same value of initial concentration of CP. Correspondingly, the total CP decomposition process was accompanied by high power inputs. It is suggested to use mentioned above method for effective CP decomposition at high concentration values.

Sosnin, E. A.; Matafonova, G. G.; Batoev, V. B.; Christofi, N.

2008-02-01

319

Novel sputtering method for Pd-Al2O3 UV transparent conductive coatings  

Microsoft Academic Search

Transparent conductive layers like indium tin oxide (ITO) or zinc oxide, that are commonly used as signal electrodes of vidicon television tubes, have an absorption edge in the visible range (350-400 nm) and therefore are not transparent in the ultra-violet (UV). We have developed the Pd-Al2O3 thin film structure which is appropriate as a signal electrode for the vidicon operating

A. Axelevitch; G. Golan; E. Rabinovitch; R. Margolin

2000-01-01

320

Validation of HPLC method for the simultaneous and quantitative determination of 12 UV-filters in cosmetics.  

PubMed

The aim of the study was the validation of a high-performance liquid chromatography (HPLC) method for the simultaneous and quantitative determination of twelve commonly used organic UV-filters (phenylbenzimidazole sulfonic acid, benzophenone-3, isoamyl p-methoxycinnamate, diethylamino hydroxybenzoyl hexyl benzoate, octocrylene, ethylhexyl methoxycinnamate, ethylhexyl salicylate, butyl methoxydibenzoylmethane, diethylhexyl butamido triazone, ethylhexyl triazone, methylene bis-benzotriazolyl tetramethylbutylphenol and bis-ethylhexyloxyphenol methoxyphenyl triazine) contained in suncare products. The separation and quantitative determination was performed in <30 min, using a Symmetry Shield(R) C18 (5 microm) column from Waters and a mobile phase (gradient mode) consisting of ethanol and acidified water. UV measurements were carried out at multi-wavelengths, according to the absorption of the analytes. PMID:20412202

Nyeborg, M; Pissavini, M; Lemasson, Y; Doucet, O

2010-02-01

321

Determination of meloxicam in human plasma using a HPLC method with UV detection and its application to a pharmacokinetic study.  

PubMed

A simple and sensitive high performance liquid chromatography method using UV detection (HPLC-UV) for the determination of meloxicam in human plasma was developed and validated. After extraction with diethyl ether, the chromatographic separation of meloxicam was carried out using a reverse phase Sunfire C18 column (150 mm x 4.6mm, 5 microm) with a mobile phase of acetonitrile-20mM potassium hydrogen phosphate (40:60, v/v, pH 3.5) and UV detection at a wavelength of 355 nm. The flow rate of mobile phase was 1.2 ml/min and the retention time of meloxicam and internal standard, piroxicam, was found to be 11.6 and 6.3 min, respectively. The calibration curve was linear within the concentration range, 10-2400 ng/ml (r2>0.9999). The lower limit of quantification was 10 ng/ml. This method improved the sensitivity for the quantification of meloxicam in plasma using a HPLC-UV. The mean accuracy was 98-114%. The coefficient of variation (precision) in the intra- and inter-day validation was 1.6-4.3 and 2.4-7.3%, respectively. The pharmacokinetics of meloxicam was evaluated after administering an oral dose of 15 mg to 11 healthy Korean subjects. The AUCinf, Cmax, tmax and t1/2 were 42.4+/-13.2 microg h/ml, 1445.7+/-305.5 ng/ml, 4.1+/-0.3h and 22.0+/-4.9h, respectively. PMID:17921074

Bae, Jung-Woo; Kim, Mi-Jeong; Jang, Choon-Gon; Lee, Seok-Yong

2007-09-14

322

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

323

Correlation of physicochemical changes in UV-exposed low density polyethylene films containing various UV stabilisers  

Microsoft Academic Search

Melt blown biaxially orientated, unstabilised and stabilised low density polyethylene (LDPE) films with various thicknesses were exposed in two accelerated artificial weathering devices with xenon arc (Xenotest) and fluorescent tube UV-B (QUV) sources under controlled temperature and humidity. The structural changes during combined photo- and thermal degradation have been studied using tensile tensiometric, IR spectrophotometric, and thermal analytical (DSC) techniques.

Mingguang Liu; A. Richard Horrocks; Michael E. Hall

1995-01-01

324

New Methods for Precision Radio Imaging: Field of View Control Using Convolution Functions in the u,v Plane  

NASA Astrophysics Data System (ADS)

Future radio telescope arrays, such as the Square Kilometer Array (SKA), will implement large numbers of small diameter dishes configured over large areas. This has the advantage of a naturally large field of view (FOV), and increased image fidelity and dynamic range. However, a major problem for these large arrays is varying instrumental response to radio sources across the FOV, as well as significant responses to sources outside the intended FOV. These effects can degrade image quality and sensitivity at the primary location of interest. One approach to this problem is to apply a convolution function to the uncalibrated visibility data in the time/frequency plane on a baseline-by-baseline basis, corresponding to a convolution function of uniform size and shape in the (u,v) plane. This provides precise, dynamic control over the FOV in the image plane in an internally consistent manner throughout the (u,v) data set. The effect is to reduce the sidelobe confusion contributions from secondary sources, as well as constituting intelligent time and frequency averaging as a means of reducing data volumes. The effectiveness of this method was tested on observational data using the MERLIN array in the United Kingdom. Using an updated version of the MIT Array Performance Simulator (MAPS), a simulated data set modeling the actual data set was generated for comparison. The performance of the convolution method on an actual data set is compared against the results on the simulated data set. The robustness of the method is also investigated by simulating large portions of lost or corrupted data. The results show that the use of convolution functions on uncalibrated (u,v) data is a promising method for limiting instrumental response to sources outside a user-defined FOV. This project was supported through an NSF/REU grant at MIT Haystack Observatory.

Foight, Dillon; Fish, V.; Lonsdale, C.

2009-01-01

325

Spectrophotometric Estimation of Olmesartan Medoxomil and Hydrochlorothiazide in Tablet  

PubMed Central

A simultaneous determination of olmesartan medoxomil and hydrochlorothiazide by absorption ratio spectrophotometric method has been developed in combined tablet dosage form. The method is based on measurements of absorbance at isoabsoptive point. The Beer's law obeys in the range of 10–30 ?g/ml for both olmesartan medoxomil and hydrochlorothiazide respectively. The proposed method was validated by performing recovery study and statistically.

Rote, A. R.; Bari, P. D.

2010-01-01

326

Development and Validation of an RP–LC–UV Method for the Determination of Ondansetron: Application to Pharmaceutical Dosage Forms  

Microsoft Academic Search

A new, simple, rapid, sensitive and specific isocratic RP–LC–UV method was developed and validated for the determination of\\u000a ondansetron in pharmaceutical dosage forms of orally disintegrating tablets, oral solution and injection. The LC separation\\u000a was achieved on a Hypersil C4 column (250 × 4.6 mm, 5 ?m) using a mobile phase of 50 mM potassium dihydrogen phosphate anhydrous\\u000a adjusted to pH 3.5 with orthophosphoric acid

Ravi Sheshala; Yusrida Darwis; Nurzalina Khan

2009-01-01

327

Indirect UV detection as a non-selective detection method in the qualitative and quantitative analysis of heparin fragments by high-performance capillary electrophoresis.  

PubMed

The application of capillary electrophoresis (CE) in combination with indirect UV detection for the qualitative and quantitative analysis of synthetic low-molecular-mass heparin fragments, at low pH, is described. It is demonstrated that, in contrast to direct UV detection, with indirect UV detection the signal obtained for various synthetic heparin pentasaccharides is nearly independent of their molecular structure. Moreover, the sensitivity of indirect UV detection is at least one order of magnitude higher than that of direct UV detection. CE-indirect UV detection for the qualitative and quantitative analysis of low-molecular-mass glycosaminoglycans was achieved by using 5 mM 5-sulphosalisylic acid, pH 3 or 5 mM 1,2,4-tricarboxybenzoic acid, pH 3.5 as electrophoresis buffer and chromophore. The technique is exemplified by the analysis of three pharmaceutical preparations of synthetic heparin pentasaccharides. The method employing indirect UV detection was validated with respect to repeatability, limit of detection, limit of quantitation, linearity, accuracy and ruggedness. In the indirect detection mode, the limit of detection for synthetic pentasaccharides is below 5 fmol, whereas the limit of quantitation is about 25 fmol. The method shows excellent repeatability and is linear in the femtomole-picomole range. Finally, it is demonstrated that the method is suitable for the analysis of various types of glycosaminoglycans. PMID:7921190

Damm, J B; Overklift, G T

1994-08-26

328

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

329

Dissolution study of nanocrystal powders of a poorly soluble drug by UV imaging and channel flow methods.  

PubMed

Application of drug nanocrystals provides advantageous options for the pharmaceutical formulation development of poorly soluble drugs. The objective of this study was to investigate the dissolution behavior improving effects of differently sized nanocrystals of a poorly soluble model drug, indomethacin. Nanocrystal suspensions were prepared using a top-down wet milling technique with three stabilizers: poloxamer F68, poloxamer F127 and polysorbate 80. The dissolution of the differently sized indomethacin nanocrystals were investigated using a channel flow dissolution method and by UV imaging. Unmilled bulk indomethacin and physical mixtures were used as references. According to both the dissolution methods, the dissolution properties of indomethacin were improved by the particle size reduction. UV imaging was used for the first time as a dissolution testing method for fast dissolving nanoscale material. The technique provided new information about the concentration of the dissolved drug next to the sample surface; with the smallest nanocrystals (580nm) the indomethacin concentration next to the particle surface exceeded five-fold the thermodynamic saturated indomethacin solution concentration. Thus the solubility improvement itself, not only the increased surface area for dissolution, may have an important role in the higher dissolution rates of nanocrystal formulations. Poloxamer F68 was the most optimal stabilizer in the preparation of the indomethacin nanocrystal suspensions and in the solubility and dissolution enhancement as well. PMID:23999036

Sarnes, Annika; Ostergaard, Jesper; Jensen, Sabrine Smedegaard; Aaltonen, Jaakko; Rantanen, Jukka; Hirvonen, Jouni; Peltonen, Leena

2013-08-30

330

UV Radiation  

MedlinePLUS

... you see, infrared radiation that you feel as heat, and ultraviolet (UV) radiation that you can’t see or feel. UV radiation has a shorter wavelength and higher energy than visible light. It affects human health both ...

331

A continuous visible spectrophotometric assay for aspartate transcarbamylase.  

PubMed

A continuous spectrophotometric method for assaying ATCase activity has been devised that couples the production of inorganic phosphate from the ATCase-catalyzed reaction to the phosphorolysis reaction catalyzed by purine nucleoside phosphorylase, using a chromophoric nucleotide analogue, methylthioguanosine (MESG). This latter reaction results in a change in extinction coefficient of 11,000 M-1 cm-1 at 360 nm, providing a means for continuous assay of ATCase activity by spectrophotometry in the visible light region. This delta epsilon 360 is sufficiently large to allow continuous determination of reaction rates with micromolar levels of carbamyl-phosphate, a feature not offered by other currently used assay methods. Other currently available ATCase assay methods typically include fixed-time incubations involving [14C]Asp that require multiple chromatographic separations, colorimetry requiring long incubations with corrosive chemicals in the dark, or relatively insensitive continuous approaches involving a pH stat or far uv spectrophotometry. This facile, inexpensive MESG-coupled assay can be routinely applied to studies of ATCase altered by feedback modifiers or by site-specific mutations. Saturation curves for Asp and CP determined by other methods at pH 7 and 8 have been reproduced by the MESG/PNP-coupled approach. The kinetic binding of CP was demonstrated to be non-cooperative at low [Asp], i.e., under conditions at which ATCase was primarily in the T state. Cooperative binding of CP observed under conditions of saturating [Asp] (i.e., with ATCase in the R state) appears to reflect binding of Asp rather than CP.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8074305

Wedler, F C; Ley, B W; Moyer, M L

1994-05-01

332

Spectrophotometric determination of nitrite and nitrate using phosphomolybdenum blue complex  

Microsoft Academic Search

A method for spectrophotometric determination of nitrite and nitrate is described. This method is based on the reduction of phosphomolybdic acid to phosphomolybdenum blue complex by sodium sulfide. The obtained phosphomolybdenum blue complex is oxidized by the addition of nitrite and this causes a reduction in intensity of the blue color. The absolute decrease in the absorbance of the blue

Nidal A. Zatar; Maher A. Abu-Eid; Abdullah F. Eid

1999-01-01

333

Investigation of winds in Venus mesosphere by digital method using UV images from VMC aboard Venus Express.  

NASA Astrophysics Data System (ADS)

Investigation of winds at the top cloud layer is important for understanding the global circulation of the Venus atmosphere. The Venus Monitoring Camera (VMC) aboard Venus Express has acquired a huge number of UV (365 nm) images. UV images of top cloud layer are customary to obtain the wind velocity due to their high contrast. Visual estimation of wind velocities is a labor intensive procedure. Authors have developed a digital method to estimate velocities of shifts of cloud details. The method is based on analysis of correlations between two UV images acquired at different moments. The method takes into account the change of a correlation function due to latitudinal peculiarities of cloud morphology and eliminates image regions which are far from the sub-spacecraft point. The digital method provides with good vector coverage of the Venus day side (9-16 local time) from the equator to high latitudes. The best agreement between the digital and visual methods is observed at low latitudes (below 35S). The discrepancy at higher latitudes is related to complicated cloud morphology, namely domination of streaks, which increases errors in the zonal wind speed. The method is productive for long-scale circulation at the top cloud layer. Sizes of regions for correlation were chosen empirically as a trade-off of sensitivity against noise immunity and varies from 10x7.5 ° to 20x10 ° depending on grid step. 580 orbits covering ten Venus years have been processed by using the digital method. The database of shift vectors counts about 400000 records. The mean wind speed at low latitudes is about 100 m/s. Wind vector fields were obtained for every orbit. The zonal wind speed in the equatorial region exhibits short-period (about 4.8 days) and long-period variations (long-term trend). Vector field averaged by all orbits show deviations of the main stream up to 5 degrees poleward in the early afternoon (12.5-14.5h) at 45-55S. The mean absolute value of the wind speed increases from 59.38 m/s at 10-12h to 76.46 m/s at 12.5-14.5h at the same latitude interval.

Patsaeva, Marina; Khatuntsev, Igor; Ignatiev, Nikolai

2013-04-01

334

Spectrophotometric multicomponent determination of sunset yellow, tartrazine and allura red in soft drink powder by double divisor-ratio spectra derivative, inverse least-squares and principal component regression methods.  

PubMed

Double divisor-ratio spectra derivative (graphical method), classical least-squares and principal component regression (two numerical methods) methods were developed for the spectrophotometric multicomponent analysis of soft drink powders and synthetic mixtures containing three colorants without any chemical separation. The graphical method is based on the use of derivative signals of the ratio spectra using double divisor. In this method, the linear determination ranges were 2-8 mug ml(-1) sunset yellow, 4-18 mug ml(-1) tartrazine and 2-8 mug ml(-1) allura red in 0.1 M HCl. In the numerical methods, a training set was randomly prepared by using 18 samples containing between 0 and 8 mug ml(-1) of sunset yellow, 0-18 mug ml(-1) of tartrazine and 0-8 mug ml(-1) of allura red. The chemometric calibrations were calculated by using the prepared training set and its absorbances at seven points (from 375.0 to 550.0 nm) in the spectral region 325-584 nm. The proposed methods were validated by using synthetic ternary mixtures and applied to the simultaneous determination of three colorants in soft drink powders. The obtained results were statistically compared with each other. PMID:18968786

Dinç, Erdal; Baydan, Emine; Kanbur, Murat; Onur, Feyyaz

2002-09-12

335

Development and validation of a non-aqueous reversed-phase high-performance liquid chromatographic method for the determination of four chemical UV filters in suncare formulations  

Microsoft Academic Search

A non-aqueous reversed-phase high performance liquid chromatographic method (RP–HPLC) with UV detection at 313nm was developed and validated for simultaneous determination of methylene bis-benzotriazolyl tetramethylphenol (Tinosorb M) along with three other chemical UV filters, octocrylene (Eusolex OCR), octyl methoxycinnamate (Eusolex 2292) and octyl salicylate (Eusolex OS) in suncare products. An isocratic elution was performed on a Hypersil BDS RP-C18 column

C. G Smyrniotakis; Helen A Archontaki

2004-01-01

336

Spectrophotometric Determination of HMX in PBX 9404. Period Covered: April--June 1975.  

National Technical Information Service (NTIS)

An infrared spectrophotometric method was developed for determining HMX (cyclotetramethylenetetranitramine) in PBX 9404 (a plastic-bonded explosive). In this method a sample of explosive containing about 0.450 g HMX is dissolved in 100 ml of dimethylsulfo...

C. S. MacDougall K. K. Bellamy

1975-01-01

337

Spectrophotometric observations of Comet Halley  

NASA Astrophysics Data System (ADS)

Spectrophotometric observations of comet Halley in the wavelength range (3600 - 7000) Å during the period October 15, 1985 and April 9, 1986 were made. The observed fluxes of O(1D), CN(388 nm) and C2(516 nm) are analysed in the framework of Haser's model and production rates of these cometary species are determined.

Defreitaspacheco, J. A.; Landaberry, S. J. C.; Singh, P. D.

1987-09-01

338

A simple and sensitive spectrophotometric method for the determination of trace amounts of nitrite in environmental and biological samples using 4-amino-5-hydroxynaphthalene-2,7-disulphonic acid monosodium salt  

NASA Astrophysics Data System (ADS)

A very simple, sensitive, fairly selective and rapid spectrophotometric method for the determination of trace amounts of nitrite has been described. This method is based on the diazotized intramolecular coupling of electrophilic diazonium cation with the phenolic group of 4-amino-5-hydroxynaphthalene-2,7-disulphonic acid monosodium salt (AHNDMS) in a phosphate buffer solution of pH 7.5. The cyclic product has a purple color with maximum absorbance at 560 nm and is stable for 6 h. Optimum reaction conditions and other important analytical parameters for the maximum color development were established. Beer's law was found to obey for nitrite in the concentration range of 0.1-1.6 ?g ml -1 with molar absorptivity of 2.6 × 10 4 l mol -1 cm -1 and Sandell's sensitivity of 0.0075 ?g ml -1. The effect of interfering ions on the determination is described. The recommended method was applied for the determination of nitrite in different water, soil and human saliva samples. The performance of the recommended method was evaluated in terms of Student's t-test and variance ratio F-test, which indicated the significance of proposed method over the reference method.

Nagaraja, Padmarajaiah; Al-Tayar, Naef Ghllab S.; Shivakumar, Anantharaman; Shrestha, Ashwine K.; Gowda, Avinash K.

2010-05-01

339

Spectrophotometric analysis of raloxifene hydrochloride in pure and pharmaceutical formulations.  

PubMed

Two simple and sensitive spectrophotometric methods (A and B) for the determination of raloxifene hydrochloride in bulk samples and pharmaceutical formulations are described. Method A is based on the oxidation of the drug with ferric chloride and coupling with potassium ferric cyanide. Method B is based on reduction of the drug with Fehling's reagent. Bluish green color formed in method A absorbs at 735 nm and brown color produced in method B absorbs at 430 nm. PMID:15497756

Dharuman, J; Ravichandran, V; Thirumoorthy, N; Dharamsi, A

2004-09-01

340

Spectrophotometric determination of leukocytes in urine.  

PubMed

A spectrophotometric method based on myeloperoxidase activity for the determination of leukocytes in urine is described. Red cells that may be found in urine samples were lysed by an ammonium chloride method. Leukocytes were then sedimented by centrifugation and lysed using Triton X-100 (Sigma Chemicals Co., St. Louis, MO). Myeloperoxidase-catalyzed oxidation of o-dianisidine was carried out at 37 degrees C, pH 7. The reaction was stopped with the addition of 2 M H2SO4, and a stable form of oxidized o-dianisidine in acidic solution was obtained. Solid particles that may be found in urine samples were removed by centrifugation to avoid turbidity, and absorbance values of the supernatants were recorded at 400 nm. An Average number of leukocytes were noted per number of fields by microscopic examination and were related with the absorbance values of the supernatants at 400 nm. Pearson correlation (r) between our presented spectrophotometric analysis results and visual microscopic analysis was 0.877. Roche Combur 10-test M strips (Roche, Mannheim, Germany) and Multistix 10 SG Bayer test strips (Bayer Diagnostics, UK) were 0.645 and 0.648, respectively (P < 0.0001). PMID:15202119

Imren-Eryilmaz, Eda; Kuzu-Karsilayan, Huriye; Ogan, Ayse

2004-01-01

341

Determination of citalopram in tablets by capillary zone electrophoresis and by direct and derivative UV-spectrophotometry.  

PubMed

Three rapid, simple and accurate analytical methods for the determination of citalopram in tablets were developed. The capillary zone electrophoresis (CZE) method was carried out using fused silica capillary with 67 mM phosphate buffer pH 7.0 as the background electrolyte, 30 kV of separation voltage and UV detection at 239 nm. The direct spectrophotometric method was performed by measuring the absorbance at the wavelength of 239 nm and derivative spectrophotometric assay was carried out by measuring the value of the second derivative of the spectrum at 210 nm. The linearity range for CZE method was 5-50 microg/mL and for both spectrophotometric methods was 2-12 microg/mL. The recovery in CZE was between 98.6 and 102.4%, in the direct spectrophotometry between 95.0 and 98.0% and in derivative spectrophotometry between 97.6 and 103.3%. The RSD values were between 1.36 and 2.30%, 1.80 and 2.70%, 1.52 and 2.68%, respectively. PMID:16459480

Skibi?ski, Robert; Misztal, Genowefa

342

Redox spectrophotometric method involving electrolytically generated manganese(III) sulphate with diphenylamine for the determination of ascorbic acid present in the samples of various fruits, commercial juices and sprouted food grains.  

PubMed

A spectrophotometric method was developed for ascorbic acid present in various fruits, commercial fruit juices and sprouted food grains. The method involves the oxidation of ascorbic acid with excess manganese(III) following reduction of unreacted manganese(III) with diphenylamine or barium diphenylamine sulphonate forming a product ?(max) 570 nm the system 1 or 540 nm the system 2 and decrease in the colour intensity is proportional to the concentration of vitamin C with quantification range 0.3-3.0 ?g ml(-1). The molar absorptivity and Sandell's sensitivity values of the system 1 and the system 2 were 1.829 × 10(4) and 1.813 × 10(4)mol(-1)cm(-1) and 0.0096 and 0.0097 ?g cm(-2) respectively. The stoichiometry was 4:1 between manganese(III) and diphenylamine. The ascorbic acid contents of the same samples were determined separately following the procedures of the developed method as well as the reference method and the results were comparable. PMID:23411340

Shyla, B; Nagendrappa, G

2012-11-24

343

Blends of Nylon66 with Chemically Modified ABS (mABS) Using a Novel Method of UV Irradiation  

Microsoft Academic Search

Blends of Nylon-66\\/ABS were prepared in various proportions. ABS was chemically modified using ethylene glycol, ethylene diamine and acrylamide. Butadiene region of ABS acted as site for modification reactions, irradiated by UV using UV initiator in UV reactor. m-ABS were characterized using FTIR confirming chemical functionalization. m-ABS blended with Nylon-66 and results compared with original ABS\\/N-66 blends. Physical, mechanical, chemical,

Vikram R. Singh; Neetha John

2011-01-01

344

Spectrophotometric and colorimetric determination of protein concentration.  

PubMed

This unit describes spectrophotometric and colorimetric methods for measuring the concentration of a sample protein in solution. Absorbance measurement at 280 nm is used to calculate protein concentration by comparison with a standard curve or published absorptivity values for that protein. An alternate protocol uses absorbance at 205 nm to calculate the protein concentration. Both methods can be used to quantitate total protein in crude lysates and purified or partially purified protein. Use of a spectrofluorometer or a filter fluorometer to measure the intrinsic fluorescence emission of a sample solution is also described. The measurement is compared with the emissions from standard solutions to determine the concentration of purified protein. The Bradford colorimetric method, based upon binding of the dye Coomassie brilliant blue to an unknown protein, is also presented, as is the Lowry method, which measures colorimetric reaction of tyrosyl residues in an unknown. PMID:18265371

Simonian, Michael H; Smith, John A

2006-11-01

345

Spectrophotometric Estimation of Azithromycin in Tablets  

PubMed Central

The present manuscript describes a simple, sensitive, accurate, precise and economical visible spectrophotometric method for the estimation of azithromycin from tablet formulation. The method is based on the reduction of potassium permanganate in alkaline medium with azithromycin. The measurement of decrease in absorbance of potassium permanganate at 547 nm was done, as it decolourises upon reduction by azithromycin. The method was used to determine between 2 and 20 ?g/ml of azithromycin in the final measured solution. There is no interference from the ingredients commonly found in azithromycin tablets with this method. The results for the determination of azithromycin in tablets were in good agreement with the labelled quantities and related analytical parameters are calculated.

Jayanna, B. K.; Nagendrappa, G.; Arunkumar; Gowda, N.

2012-01-01

346

Selective and sensitive spectrophotometric method for the determination of trace amounts of zirconium in environmental and biological samples using 4-chloro-N-(2,6-dimethylphenyl)-2-hydroxy-5-sulfamoylbenzamide  

NASA Astrophysics Data System (ADS)

A simple, selective and sensitive spectrophotometric method for the determination of trace amounts of Zr(IV) in aqueous samples was performed, based on complexation reaction between Zr(IV) and 4-chloro-N-(2,6-dimethylphenyl)-2-hydroxy-5-sulfamoylbenzamide (xipamide). The important analytical parameters and their effects on the reported system were investigated. Zr(IV) react with xipamide in the ratio 1:1 in the pH range 8 to form a complex with an absorption maximum 333 nm. The apparent stability constant (log ?n) and the free energy change (?G?) of formation of the complex was calculated using the results of mole ratio and continuous variation methods. Beer's law was obeyed in the concentration range 0.2-3.6 ?g/mL. For more accurate analysis, Ringbom optimum concentration range was found from 0.3 to 3.5 ?g/mL. The molar absorptivity, Sandell sensitivity, detection and quantification limits were also calculated. Taking a constant concentration of Zr(IV) and determining its concentration in the presence of large number of foreign ions tested the effect of foreign ions. The practical applicability of the elaborated method was examined using for determination of mentioned ion in water samples, biological, plant leaves and soil samples where excellent agreements between reported and obtained results were achieved. The relative standard deviation (n = 6) were 0.195%. The precision and accuracy of the results were comparable via F and t test at the 95% confidence level.

Al-Kady, Ahmed S.

2012-11-01

347

Simultaneous ultraviolet spectrophotometric determination of nitrate and nitrite in water  

SciTech Connect

A rapid and accurate method for the direct simultaneous determination of nitrate and nitrite is proposed. The method is applied to the determination of nitrate and nitrite in rainwater and wastewater without preliminary separation. The determinations are performed by a CPA matrix method with ultraviolet spectrophotometric detection. The results obtained are in agreement with those obtained by conventional methods for the determination of nitrate and nitrite.

Dong Huiru; Zhang Qing (Liaoyang Petrochemical College (China)); Jiang Meiyu (Liao Hua Oil Refinery, Liaoyang (China))

1991-02-01

348

UV LED Space Qualification  

NASA Astrophysics Data System (ADS)

Electric charges induced by cosmic rays tend to accumulate on the free floating proof mass at the core of a drag-free satellite. The Lorentz force will affect stationarity of the proof mass. Generation of photoelectrons via ultraviolet (UV) light is an effective method of charge management. Previous missions have relied on mercury lamps as a UV light source. We have proposed the use of UV LEDs as a source for UV light generation, because they have significantly lower mass and power requirements. Since 2005, we have conducted systematic UV LED power and spectral lifetime tests. The UV LED has now been operated more than 16,668 hours (as of submission of this abstract) without significant power decay. At the 10,000 hour mark, the UV LED spectral shift was measured to be approximately 1 nm towards shorter wavelengths. To fully simulate the space environment, we have initiated another UV LED lifetime test in 1E-7 torr vacuum chamber starting in January 2008. Thus far the UV LED output has been stable without noticeable degradation. We have conducted a large dose radiation test using an accelerator source for 59.0 64.8 MeV proton generation. For proton flux from 10E10 to 2E12 protons per square centimeter, there was no significant power drop and spectral shift for UV LED light output, This level of radiation test exceeded 100 years of radiation dose at deep space LISA orbits. The combination of the successful tests in power lifetime, spectral stability, and radiation hardness have proven that UV LED should be the primary choice for the charge management system for LISA and other high precision space flights.

Buchman, Saps; Sun, K.; Leindecker, N.; Higuchi, S.; Byer, R.; Goebel, J.

2009-01-01

349

Validation of an HPLC-UV method for the determination of ceftriaxone sodium residues on stainless steel surface of pharmaceutical manufacturing equipments  

Microsoft Academic Search

In pharmaceutical industry, an important step consists in the removal of possible drug residues from the involved equipments and areas. The cleaning procedures must be validated and methods to determine trace amounts of drugs have, therefore, to be considered with special attention. An HPLC-UV method for the determination of ceftriaxone sodium residues on stainless steel surface was developed and validated

Magda A. Akl; Mona A. Ahmed; Ahmed Ramadan

2011-01-01

350

The Gaia Spectrophotometric Standard Stars  

NASA Astrophysics Data System (ADS)

The paper describes the spectrophotometric instrument of Gaia ESA's mission and the principles of the internal and absolute calibrations of the measurements. Special emphasis is made on the ongoing observational survey aimed at building a grid of about 200 spectrophotometric standard stars, with an internal precision of 1% and tied to Vega within a few percent, for the absolute flux calibration of Gaia photometry. Until now, more than 400 observing nights were devoted to the project, distributed in several observatories (CAHA in Almería, TNG in La Palma, NTT in La Silla, San Pedro Mártir in México, Loiano in Italy, and many partial nights with robotic REM in La Silla) and for both spectroscopic and photometric campaigns (Pancino et al. 2012, MNRAS, 426, 1767). Additional observations are still needed for finalising the absolute photometric calibrations and for continuing the monitoring of variability (short and long term) in order to discard non optimal candidates.

Jordi, C.; Carrasco, J. M.; Pancino, E.; Altavilla, G.; Marinoni, S.; Cocozza, G.; Figueras, F.; Voss, H.; Galleti, S.; Ragaini, S.; Schuster, W.; Fabricius, C.; Monguió, M.; Masana, E.; Bellazzini, M.; Cacciari, C.; Bragaglia, A.; Weiler, M.; Bragaglia, A.

2013-05-01

351

ZnO coaxial nanorod Homojunction UV light-emitting diodes prepared by aqueous solution method.  

PubMed

The fabrication of a p-shell/n-core coaxial nanorod ZnO homojunction light-emitting diode by inexpensive solution method is demonstrated. The p-type conductivity of the ZnO shell arises from the incorporation of potassium while the n-type conductivity of the core is due to unintentional doping. PMID:22334368

Nguyen, Xuan Sang; Tay, Chuan Beng; Fitzgerald, Eugene A; Chua, Soo Jin

2012-02-15

352

A Novel Method for Monitoring the Transesterification Reaction of Oil in Biodiesel Production by Estimation of Glycerol  

Microsoft Academic Search

A quantitative method is reported for the estimation of glycerol during transesterification of oil to form biodiesel. The\\u000a reagent used to derivatize glycerol was 9,9-dimethoxyfluorene. Glycerol is estimated by both UV–visible spectrophotometric\\u000a and high performance liquid chromatography methods. Using the former method, detection limits of 0.05% w\\/w of glycerol in\\u000a biodiesel was established. Validation of the developed method was done

Sabbasani Rajasekhara Reddy; Devamani Titu; Anju Chadha

2010-01-01

353

Simultaneous derivative spectrophotometric analysis of doxylamine succinate, pyridoxine hydrochloride and folic Acid in combined dosage forms.  

PubMed

Two UV spectrophotometric methods have been developed, based on first derivative spectrophotometry for simultaneous estimation of doxylamine succinate, pyridoxine hydrochloride, and folic acid in tablet formulations. In method I, the concentrations of these drugs were determined by using linear regression equation. Method II is also based on first derivative spectrophotometry however simultaneous equations (Vierdot's method) were derived on derivative spectra. The first derivative amplitudes at 270.0, 332.8 and 309.2 nm were utilized for simultaneous estimation of these drugs respectively by both methods. In both the methods, linearity was obtained in the concentration range 2.5-50 mug/ml, 1-40 mug/ml and 1-30 mug/ml for doxylamine succinate, pyridoxine hydrochloride, and folic acid respectively. The developed methods show best results in terms of linearity, accuracy, precision, LOD, LOQ and ruggedness for standard laboratory mixtures of pure drugs and marketed formulations. The common excipients and additives did not interfere in their determinations. PMID:20046784

Pathak, A; Rajput, S J

354

Simultaneous Derivative Spectrophotometric Analysis of Doxylamine Succinate, Pyridoxine Hydrochloride and Folic Acid in Combined Dosage Forms  

PubMed Central

Two UV spectrophotometric methods have been developed, based on first derivative spectrophotometry for simultaneous estimation of doxylamine succinate, pyridoxine hydrochloride, and folic acid in tablet formulations. In method I, the concentrations of these drugs were determined by using linear regression equation. Method II is also based on first derivative spectrophotometry however simultaneous equations (Vierdot's method) were derived on derivative spectra. The first derivative amplitudes at 270.0, 332.8 and 309.2 nm were utilized for simultaneous estimation of these drugs respectively by both methods. In both the methods, linearity was obtained in the concentration range 2.5-50 ?g/ml, 1-40 ?g/ml and 1-30 ?g/ml for doxylamine succinate, pyridoxine hydrochloride, and folic acid respectively. The developed methods show best results in terms of linearity, accuracy, precision, LOD, LOQ and ruggedness for standard laboratory mixtures of pure drugs and marketed formulations. The common excipients and additives did not interfere in their determinations.

Pathak, A.; Rajput, S. J.

2008-01-01

355

A Computer Program to Process Spectrophotometric Analytical Data Associated with Curvilinear Absorbance/Concentration Relationships.  

National Technical Information Service (NTIS)

A computer program designed to provide a simple and accurate method for evaluating spectrophotometric assay data accommodates both linear and nonlinear standard curves. The program requires manual entry by keyboard of absorbance and concentration values f...

J. J. Knudsen E. L. Mcgown

1981-01-01

356

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

357

Development of a reliable analytical method for extraction spectrophotometric determination of ruthenium(III) from catalyst and fissium alloy using o-methylphenyl thiourea as a chromogenic chelating ligand  

NASA Astrophysics Data System (ADS)

A simple and selective method is developed for the extraction spectrophotometric determination of ruthenium(III) using o-methylphenyl thiourea (OMPT) as a chromogenic chelating ligand. The basis of the proposed method is ruthenium(III)-OMPT complex formation in aqueous hydrochloric acid media (3.0 mol L-1) after 5.0 min heating on a boiling water bath and the complex formed is extracted into chloroform. The absorbance of green colored ruthenium(III)-OMPT complex is measured at 590 nm against the reagent blank. Beer's law was obeyed up to 42.5 ?g mL-1 of ruthenium(III) and the optimum concentration range is 7.56-39.81 ?g mL-1 of ruthenium(III) as evaluated by Ringbom's plot. Molar absorptivity and Sandell's sensitivity of ruthenium(III)-OMPT complex in chloroform are 2.34 × 103 L mol-1 cm-1 and 0.043 ?g cm-2 respectively. The composition of ruthenium(III):OMPT complex (1:2) was established from slope ratio method, mole ratio method and Job's continuous variation method. Complex was stable for more than 48 h. The interfering effect of various foreign ions was studied and suitable masking agents are used wherever necessary to enhance the selectivity of the method. Proposed method is successfully applied for determination of ruthenium(III) from binary and ternary synthetic mixtures, synthetic mixtures corresponding to fissium alloy and ruthenium catalyst. Repetition of the method was checked by finding relative standard deviation (R.S.D) for 10 determinations which was 0.23%. A scheme for sequential separation of palladium(II), ruthenium(III), rhodium(III) and platinum(IV) has been developed.

Kuchekar, Shashikant R.; Shelar, Yogesh S.; Aher, Haribhau R.; Han, Sung H.

2013-04-01

358

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.

Mowafy, Hammam A.; Alanazi, Fars K.; El Maghraby, Gamal M.

2011-01-01

359

A validated method for the determination of traces of UV filters in fish using LC-MS/MS.  

PubMed

An analytical method for the determination of UV filter substances in fish tissue has been developed and validated using benzophenone-3, 3-(4-methylbenzylidene)-camphor, 2-ethylhexyl-2-cyano-3,3-diphenyl-2-propenoate and 2-ethylhexyl 3-(methoxyphenyl)-2-propenoate as target analytes. The fish fillets were homogenised and extracted by Soxhlet extraction. The extracts were run through a clean-up process including gel permeation chromatography followed by solid-phase extraction. Quantification of the compounds was performed using liquid chromatography with tandem mass spectrometric detection. Blank fish as well as spiked blank fish were analysed to validate the analytical method. The analytical method developed has the multiple advantages of enabling separation, simultaneous identification and quantification of each of the four selected compounds in a single run. Contamination of blank samples and abnormally high concentrations in spiked samples were avoided by taking extensive precautions during the fish preparation procedure. The method was validated in accordance with internationally accepted criteria, such as specificity, accuracy and repeatability. The combination of LC with tandem mass spectrometry ensures a high level of specificity. The accuracy of the method was reported as the mean recovery rate for the analytes in the sample matrix. Mean recoveries were in the range 86-108%. The precision is expressed as the relative standard deviation, and in all but one of the cases was 20% or below. The accuracy of the method allows residue analyses to be performed on biological matrices at ng/g levels. The determined limit of quantification for each analyte was 8 ng/g fish. For all spiking levels > or =8 ng/g, relative standard deviations were < or = 20%. PMID:17072605

Meinerling, Maria; Daniels, Marion

2006-10-03

360

Spectrophotometric and HPTLC-densitometric determination of lisinopril and hydrochlorothiazide in binary mixtures  

Microsoft Academic Search

Different spectrophotometric and HPTLC-densitometric methods are presented for the simultaneous determination of lisinopril and hydrochlorothiazide in pharmaceutical tablets. The spectrophotometric methods include third derivative (3D) ultraviolet spectrophotometry with zero crossing measurement at 217.4 and 233.4 nm, second derivative of the ratio spectra with measurement at 214.3 and 228.0 nm; both classical least squares and principal component regression were applied to

Alaa El-Gindy; Ahmed Ashour; Laila Abdel-Fattah; Marwan M Shabana

2001-01-01

361

Flow injection spectrophotometric determination of ultra trace amounts of oxalic acid  

Microsoft Academic Search

A new simple, sensitive and rapid catalytic-spectrophotometric method for the determination of oxalic acid has been described\\u000a based on its catalytic effect on the redox reaction between dichromate and Brilliant cresyl blue in acidic media by means\\u000a of a flow injection analysis method. The color change of Brilliant cresyl blue due to its oxidation was monitored spectrophotometrically\\u000a at 625 nm.

Ali A. Ensafi; A. Kazemzadeh

2000-01-01

362

Spectrophotometric Determination of Hydrazine  

Microsoft Academic Search

A simple sensitive and selective method is described for the determination of trace amounts of hydrazine. The method is based on the reduction of nitrate to nitrite. Hydrazine in ammoniacal condition is used as reducing agent with copper(II) as catalyst. The nitrite prepared is determined based on the diazo coupling reaction between p?nitroaniline and N?(1?naphthyl)ethylenediammine dihydrochloride(NEDA). The method obeys Beer's

Mary George; K. S. Nagaraja; N. Balasubramanian

2007-01-01

363

Spectrophotometric determination of ofloxacin in pharmaceuticals by redox reaction  

Microsoft Academic Search

Two simple spectrophotometric methods have been developed to analyze ofloxacin (OFX) in pharmaceuticals. The methods are based on the oxidation of OFX by a measured excess of cerium(IV) sulfate in H2SO4 medium. This was followed by the determination of the unreacted oxidant by reacting it with either p-toluidine ( p-TD) and measuring the absorbance at 525 nm (method A) or

P. J. Ramesh; K. Basavaiah; N. Rajendraprasad; O. Zenita Devi; K. B. Vinay

2011-01-01

364

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

365

Validated RP-HPLC method for determination of permethrin in bulk and topical preparations using UV-vis detector.  

PubMed

An isocratic reversed-phase high-performance liquid chromatographic method for the estimation of permethrin in raw materials and pharmaceutical topical preparations has been devised and validated. The chromatographic analysis was performed on a 5 ?m particle C-18 Nucleosil (Macherey-Nagel, Germany) column (250 × 4.6 mm). Mobile phase consisted of methanol and 0.025 mM Phosphoric acid (85:15 v/v) at a flow rate of 1.5 mL/min. UV detection was performed at 272 nm and peaks were identified with retention times as compared with standards. The limit of detection was 1.782 ?g/mL, while limit of quantitation was 48.0 ?g/mL. The calibration was linear in a concentration range of 48.0-5000 ?g/mL with correlation coefficient of 0.999978. Regression equation was absorbance =2833.23 × concentration(?g/mL) + 19.1045 with variance of the response variable, S(yx)(2), calculated to be 1.75328 (six degrees of freedom). The method was validated as per ICH guidelines and USP requirements and found advantageous for the routine analysis of the drug in pharmaceutical formulations and in pharmaceutical investigations involving permethrin. PMID:21439119

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

2011-04-01

366

Adsorption of basic dyes from single and binary component systems onto bentonite: simultaneous analysis of Basic Red 46 and Basic Yellow 28 by first order derivative spectrophotometric analysis method.  

PubMed

The present study deals with the simultaneous analysis and adsorption of Basic Yellow 28 and Basic Red 46 dyes in binary mixture onto bentonite. First order derivative spectrophotometric method was used for simultaneous analysis of BY28 and BR46 in binary mixtures. The adsorption experiments were carried out in a batch system. The mono- and multi-component Langmuir and Freundlich isotherm models were applied to experimental data and the isotherm constants were calculated for BY28 and BR46 dyes. The monolayer coverage capacities of bentonite for BY28 and BR46 dyes in single solution system were found as 256.4 mg/g and 333.3mg/g, respectively. It was observed that the equilibrium uptake amounts of BY28 and BR46 dyes in binary mixture onto bentonite decreased considerably with increasing concentrations of the other dye resulting in their antagonistic effect. The adsorption equilibrium data fitted more adequately to mono-component Langmuir isotherm model than mono-component Freundlich isotherm model, while the extended Freundlich isotherm model adequately predicted the multi-component adsorption equilibrium data at moderate ranges of concentration. Thermodynamic parameters showed that adsorption of BR46 and BY28 was endothermic and spontaneous in nature. PMID:18289779

Turabik, Meral

2008-01-19

367

RP-HPLC and Spectrophotometric Estimation of Ambroxol Hydrochloride and Cetirizine Hydrochloride in Combined Dosage Form  

PubMed Central

Rapid, precise, accurate, specific and sensitive reverse phase liquid chromatographic and absorbance ratio spectrophotometric methods have been developed for the simultaneous analysis of ambroxol hydrochloride and cetirizine hydrochloride in their tablet formulation. The chromatographic methods were standardized using a HIQ SIL-C18 column (250×4.6 mm i.d., 10 ?m particle size) with UV detection at 229 nm and mobile phase consisting of methanol-acetonitrile-water (40:40:20, v/v/v). Ambroxol hydrochloride and cetirizine hydrochloride have absorbance maxima at 243 nm and 229 nm, respectively. The isoabsorptive wavelength for both the drugs was 236 nm. For absorbance ratio method developed, wavelengths selected were 243 nm and 236 nm. The proposed methods were successfully applied to the determination of ambroxol hydrochloride and cetirizine hydrochloride in tablets, with high percentage of recovery, good accuracy and acceptable precision. Different analytical performance parameters such as linearity, precision, accuracy, limit of detection, limit of quantitation and robustness were determined according to International Conference on Harmonization ICH Q2B guidelines. Results of analysis of the developed method were compared by performing ANOVA.

Bhatia, Neela M.; Ganbavale, S. K.; Bhatia, M. S.; More, H. N.; Kokil, S. U.

2008-01-01

368

Spectrophotometric determination of certain antidepressants in pharmaceutical preparations.  

PubMed

Simple and reproducible spectrophotometric methods have been developed for determination of sertraline, fluoxetine, and venlafaxine in pharmaceutical preparations. The methods are based on the reactions between the studied drug substances and ion-pair agents (bromothymol blue, bromocresol green, or bromophenol blue) to produce yellow-colored ion-pair complexes in acidic buffers. After extracting in chloroform, the ion-pair complexes are spectrophotometrically determined at the optimum wavelength. Optimizations of the reaction conditions were carried out. Beer's law was obeyed within the concentration range from 1 to 15 microg/mL. The molar absorptivity, Sandell sensitivity, and detection and quantification limits were also determined. The developed methods were applied successfully for the determination of these drugs in some available commercial preparations. The results were compared statistically with those obtained from reported high-performance liquid chromatography methods. PMID:16915831

Onal, Arma?an; Kepekci, S Evrim; Cetin, S Müge; Ertürk, Sidika

369

Extractive spectrophotometric determination of TRODAT-1 hydrochloride in lyophilized kit.  

PubMed

A simple, sensitive, and accurate spectrophotometric method has been developed for the assay of TRODAT-1 hydrochloride in lyophilized kit. The method is based on the formation of ion-pair association complex of TRODAT-1 with bromothymol blue (BTB) in disodium hydrogen phosphate/citric acid buffer of pH 4.0. The colored product was extracted with chloroform, and measured spectrophotometrically at 414 nm. Beer's law was obeyed in the range of 5-25 microg/ml with molar absorptivity of 2.75 x 10(4) l/mol/cm. Optimization of experimental conditions was described for the method. The proposed method has been successfully applied for the analysis of TRODAT-1 hydrochloride in lyophilized kit. No interference with pharmaceutical excipients was observed. PMID:18819514

Li, X M; Chen, Z P; Wang, S P; Tang, J; Liu, C Y; Zou, M F

2008-09-01

370

Screening of conditions controlling spectrophotometric sequential injection analysis  

PubMed Central

Background Despite its potential benefits over univariate, chemometrics is rarely utilized for optimizing sequential injection analysis (SIA) methods. Specifically, in previous vis-spectrophotometric SIA methods, chemometrically optimized conditions were confined within flow rate and reagent concentrations while other conditions were ignored. Results The current manuscript reports, for the first time, a comprehensive screening of conditions controlling vis-spectrophotometric SIA. A new diclofenac assay method was adopted. The method was based on oxidizing diclofenac by permanganate (a major reagent) with sulfuric acid (a minor reagent). The reaction produced a spectrophotometrically detectable diclofenac form. The 26 full-factorial design was utilized to study the effect of volumes of reagents and sample, in addition to flow rate and concentrations of reagents. The main effects and all interaction order effects on method performance, i.e. namely sensitivity, rapidity and reagent consumption, were determined. The method was validated and applied to pharmaceutical formulations (tablets, injection and gel). Conclusions Despite 64 experiments those conducted in the current study were cumbersome, the results obtained would reduce effort and time when developing similar SIA methods in the future. It is recommended to critically optimize effective and interacting conditions using other such optimization tools as fractional-factorial design, response surface and simplex, rather than full-factorial design that used at an initial optimization stage. In vis-spectrophotometric SIA methods those involve developing reactions with two reagents (major and minor), conditions affecting method performance are in the following order: sample volume > flow rate ? major reagent concentration >> major reagent volume ? minor reagent concentration >> minor reagent volume.

2011-01-01

371

Studies of curcumin and curcuminoids. XXXVI. The stoichiometry and complexation constants of cyclodextrin complexes as determined by the phase-solubility method and UV–Vis titration  

Microsoft Academic Search

Cyclodextrin (CD) complex stoichiometry and complexation constant with two symmetric curcuminoids and two unsymmetric curcuminoid-like\\u000a compounds were investigated and compared by two independent methods, the phase-solubility method and ultraviolet-visible absorption\\u000a spectroscopy (UV–Vis) titration. Two different methods were applied in an effort to increase the apparent intrinsic solubility\\u000a of the compounds and make the investigation of stoichiometry and complexation constants possible.

Ravinder Singh; Hanne Hjorth Tønnesen; Stine Byskov Vogensen; Thorsteinn Loftsson; Már Másson

2010-01-01

372

Preclinical Monitoring of Drug Association in Experimental Chemotherapy of Chagas' Disease by a New HPLC-UV Method  

PubMed Central

A combination of drugs in experimental chemotherapy of Chagas' disease may increase the effectiveness of treatment. To evaluate the possible mechanisms that influence the improvement of therapy, we investigated the pharmacokinetic interaction between benznidazole and itraconazole in a murine model treated orally with single doses of 5 mg of each compound separately or together. Blood samples from treated mice were collected at different intervals for 48 h, and a high-performance liquid chromatography (HPLC)-UV method was used to quantify both drugs in the plasma. A decrease of 1.5-fold in the maximum drug concentration in the plasma (Cmax) and an increase of 2.66-fold in the volume of distribution (V) and 7.5-fold in the elimination half-life (t1/2?) of benznidazole when coadministered with itraconazole were observed. The parameters area under the curve (AUC0-t), area under the curve extrapolated to infinity (AUC0-?), time to maximum concentration of drug in serum (Tmax), and clearance (CL) for benznidazole were not significantly different in this therapeutic regime. None of the evaluated parameters for ITC demonstrated a significant difference between isolated and associated administration. These results suggest that the main effect of this interaction leads to accumulation of benznidazole in the biological system. This effect may contribute to the improved therapeutic efficacy of this combination of drugs, in addition to synergism of the different mechanisms of action of benznidazole and itraconazole against Trypanosoma cruzi in vivo.

Moreira da Silva, Rodrigo; Oliveira, Liliam Teixeira; Silva Barcellos, Neila Marcia; de Souza, Jacqueline

2012-01-01

373

Preclinical monitoring of drug association in experimental chemotherapy of Chagas' disease by a new HPLC-UV method.  

PubMed

A combination of drugs in experimental chemotherapy of Chagas' disease may increase the effectiveness of treatment. To evaluate the possible mechanisms that influence the improvement of therapy, we investigated the pharmacokinetic interaction between benznidazole and itraconazole in a murine model treated orally with single doses of 5 mg of each compound separately or together. Blood samples from treated mice were collected at different intervals for 48 h, and a high-performance liquid chromatography (HPLC)-UV method was used to quantify both drugs in the plasma. A decrease of 1.5-fold in the maximum drug concentration in the plasma (C(max)) and an increase of 2.66-fold in the volume of distribution (V) and 7.5-fold in the elimination half-life (t(1/2?)) of benznidazole when coadministered with itraconazole were observed. The parameters area under the curve (AUC(0-t)), area under the curve extrapolated to infinity (AUC(0-?)), time to maximum concentration of drug in serum (T(max)), and clearance (CL) for benznidazole were not significantly different in this therapeutic regime. None of the evaluated parameters for ITC demonstrated a significant difference between isolated and associated administration. These results suggest that the main effect of this interaction leads to accumulation of benznidazole in the biological system. This effect may contribute to the improved therapeutic efficacy of this combination of drugs, in addition to synergism of the different mechanisms of action of benznidazole and itraconazole against Trypanosoma cruzi in vivo. PMID:22450981

Moreira da Silva, Rodrigo; Oliveira, Líliam Teixeira; Silva Barcellos, Neila Márcia; de Souza, Jacqueline; de Lana, Marta

2012-03-26

374

Spectrophotometric assay of ethamsylate using a tetrazolium salt  

Microsoft Academic Search

A spectrophotometric assay method for ethamsylate in prepared medicinal formulations and biological fluids was developed.\\u000a The method is based on the reduction of p-nitrotetrazolium chloride by ethamsylate in n-propanol in the presence of sodium hydroxide followed by measurement of the optical density of the resulting colored solution\\u000a at ?max = 490 nm. The detection limit was 0.32 ?g\\/100 ml. The

O. A. Tarkhanova; S. A. Vasyuk

2010-01-01

375

Selective spectrophotometric determination of p-aminophenol and acetaminophen  

Microsoft Academic Search

A specific spectrophotometric method was developed for the determination of p-aminophenol and acetaminophen. The method is based on the reaction of p-aminophenol at ambient temperature with sodium sulphide in presence of an oxidant to produce a methylene blue-like dye. Different oxidizing agents were tried, e.g. Ce(IV) and Fe(III). The colour developed within 10 min and remained stable for at least

Fardous A. Mohamed; Mohamed A. AbdAllah; Soad M. Shammat

1997-01-01

376

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

377

Spectrophotometric phosphate determination in urine by ligand exchange extraction  

Microsoft Academic Search

A new spectrophotometric method for the determination of phosphate in urine is proposed, based on the ligand exchange extraction produced by phosphate solution at pH 7.5 when it is shaken with a solution of Fe(III) indole-2-carboxylate iniso-amyl alcohol. The organic layer decoloration is measured at 400 nm and the phosphate indirectly determined. The sensitivity of the method is 1.07 ×

Elisa Lozano-Chaves; Maria-Purificación Hernández-Artiga; Antonio Muñoz-Leyva

1994-01-01

378

A rapid High Performance Liquid Chromatographic (HPLC) method for the simultaneous determination of seven UV filters found in sunscreen and cosmetics.  

PubMed

A rapid High Performance Liquid Chromatographic (HPLC) method was developed for the simultaneous determination of seven Ultra Violet (UV) filters most commonly found in cosmetics and sunscreen. The object of the method development was to provide a reliable rapid method, that would simultaneously separate a combination of the UV Filters, most commonly found in cosmetics and sunscreen products, utilizing a minimum of environmentally friendly solvents. The compounds separated were: benzophenone 3 (BZ3), methylbenzildene camphor (MBC), octyl dimethyl PABA (ODP), octocrylene (OCR), octyl methoxycinnamate (OMC), butyl - methoxydibenzoylmethane (BDM) and octyl salicylate (OS). An adjusted mobile phase consisting of ethanol and 1% acetic acid, combined with a Thermo Hypersil C(18) BDS 3 micron column resulted in a method, which allowed the analysis of the seven compounds in seven minutes. The proposed method was validated utilising the International Congress on Harmonisation (ICH) and the Food and Drug Administration (FDA) guidelines. All parameters examined were found to be well within the stated guidelines. PMID:20807259

Wharton, M; Geary, M; O'Connor, N; Murphy, B

2010-08-30

379

Spectrophotometric and electrical studies of charge-transfer complexes of sodium flucloxacillin with ?-acceptors  

Microsoft Academic Search

The present study is interested to develop a simple, rapid and accurate spectrophotometric method for determination of sodium flucloxacillin (fluc) in pure form and pharmaceutical formulations. The charge-transfer (CT) interactions between sodium flucloxacillin as electron donor and chloranilic acid (CLA), dichloroquinone 4-chloroimide (DCQ), 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and 7,7,8,8 tetracyano-p-quinodimethane (TCNQ), as ?-electron acceptors have been investigated spectrophotometrically. Different variables affecting the

Moamen S. Refat; Akram M. El-Didamony

2006-01-01

380

Selective and sensitive spectrophotometric method for the determination of trace amounts of zirconium in environmental and biological samples using 4-chloro-N-(2,6-dimethylphenyl)-2-hydroxy-5-sulfamoylbenzamide.  

PubMed

A simple, selective and sensitive spectrophotometric method for the determination of trace amounts of Zr(IV) in aqueous samples was performed, based on complexation reaction between Zr(IV) and 4-chloro-N-(2,6-dimethylphenyl)-2-hydroxy-5-sulfamoylbenzamide (xipamide). The important analytical parameters and their effects on the reported system were investigated. Zr(IV) react with xipamide in the ratio 1:1 in the pH range 8 to form a complex with an absorption maximum 333 nm. The apparent stability constant (log?(n)) and the free energy change (?G) of formation of the complex was calculated using the results of mole ratio and continuous variation methods. Beer's law was obeyed in the concentration range 0.2-3.6 ?g/mL. For more accurate analysis, Ringbom optimum concentration range was found from 0.3 to 3.5 ?g/mL. The molar absorptivity, Sandell sensitivity, detection and quantification limits were also calculated. Taking a constant concentration of Zr(IV) and determining its concentration in the presence of large number of foreign ions tested the effect of foreign ions. The practical applicability of the elaborated method was examined using for determination of mentioned ion in water samples, biological, plant leaves and soil samples where excellent agreements between reported and obtained results were achieved. The relative standard deviation (n=6) were 0.195%. The precision and accuracy of the results were comparable via F and t test at the 95% confidence level. PMID:22771563

Al-Kady, Ahmed S

2012-06-17

381

Uv Throughput  

NASA Astrophysics Data System (ADS)

GRW+70d5824 is observed shortly before and after a DECON through all the UV filters in each chip and through F160BW crossed with F130LP, F185LP, and F165LP (where applicable) to determine the wavelength dependence of the throughput across the bandpass (hence color terms). Based on no particular cycle 4 program, this program is designed to better characterize the spectral response curve in the UV, and the spectral shape introduced by the contamination. Overall discrepencies between the updated synthetic photometric products and the results of this test should be 1-2% rms. This does not mean that the UV throughput will be known to this accuracy primarily because of uncertainties in the flux calibration of the standard used (5%) uncertainties in the UV flatfields (maybe 3% near the chip center), and time dependent contamination corrections (3% error), and uncertainties in the CTE correction (2%). The derived UV absolute photometry accuracy at the center of the chips should therefore be about 10%. After pipeline processing, each image will be reduced by aperture photometry. The throughput curves and their normalizations can be updated by trial and error. Expected to run 8/95. NOTE: crossed filters exposures should be observed in ALL chips after decontamination, but just in WF3 before decontamination.

Casertano, Stefano

1995-07-01

382

Automated determination of amisulpride by liquid chromatography with column switching and spectrophotometric detection.  

PubMed

A fully automated chromatographic method including on-line blood serum or plasma clean-up, isocratic high-performance liquid chromatography (HPLC) and spectrophotometric detection was developed for quantitative analysis of the new antipsychotic drug amisulpride. After injection of serum or plasma onto the HPLC system and clean-up on a pre-column (10x4.0 mm I.D.) filled with Silica CN 20 micrometer (pore size 10 nm) by an eluent consisting of 8% acetonitrile in deionized water, the chromatographic separation was performed on Lichrospher CN (5 micrometer; 250x4.6 mm I.D.) by an eluent consisting of 50% acetonitrile and 50% aqueous potassium phosphate buffer (0.008 M, pH 6.4). The UV detector was set at 254 nm. The limit of quantification was about 10 microgram/l. The method revealed linearity between 10 and 600 microgram/l (correlation coefficients R(2)>0.9996). The inter-assay reproducibility (coefficient of variation) of quality control samples was between 2.8 and 11.3%. Inaccuracy was between -0.6 and +9.1%. The performance of daily calibration standards revealed an imprecision always below 15% and maximum inaccuracy of 7.7%. The method can be applied to therapeutic drug monitoring as well as pharmacokinetic studies of amisulpride. PMID:12505788

Sachse, Julia; Härtter, Sebastian; Weigmann, Harald; Hiemke, Christoph

2003-02-01

383

Simple and rapid high-performance liquid chromatographic method for determination of celecoxib in plasma using UV detection: Application in pharmacokinetic studies  

Microsoft Academic Search

A rapid, sensitive and reproducible HPLC method was developed and validated for the analysis of celecoxib in human plasma. The analysis was carried out on a monolithic silica column using UV detection at 254nm. The assay enables the measurement of celecoxib for therapeutic drug monitoring with a minimum quantification limit of 10ngml?1. The method involves simple, one-step extraction procedure, and

A. Zarghi; A. Shafaati; S. M. Foroutan; A. Khoddam

2006-01-01

384

Neutron activation analysis as a tool for checking the reliability of spectrophotometric methods for the determination of molybdenum and tungsten in biological materials  

Microsoft Academic Search

A new method for the simultaneous determination of molybdenum and tungsten in biological materials by neutron activation analysis has been developed. It involves a single step radiochemical separation of both elements by extraction chromatography using -benzoinoxime supported on Bio-Beads SM 2. Good accuracy and precision of the method was demonstrated analyzing Bowen's Kale and IAEA's H-8 \\/Horse Kidney\\/ reference materials.

B. Danko; R. ?obinski; R. Dybczy?ski

1989-01-01

385

Stability-indicating derivative spectrophotometry method for the determination of biapenem in the presence of its degradation products  

Microsoft Academic Search

A first-derivative UV spectrophotometric method, with or without the subtraction technique, was developed for the determination\\u000a of biapenem in pharmaceutical dosage form in the presence of its degradation products. The method was based on the measurement\\u000a of first-derivative amplitudes at zero crossing point (? = 312 nm) and the peak-to-zero technique and validated with regard\\u000a to linearity, limits of detection

Judyta Cielecka-Piontek; Aran Lunzer; Anna Jeli?ska

2011-01-01

386

Spectrophotometric determination of pefloxacin mesylate in pharmaceuticals.  

PubMed

A spectrophotometric method is described for assay of pefloxacin mesylate (PFM) in bulk drug and in tablets. The method is based on back extraction of the bromophenol blue dye at pH 5.2 from the dye-drug ion pair followed by measurement of the dye absorbance at 590 nm. The working conditions of the method were investigated and optimized. Beer's law plot showed a good correlation in the concentration range of 0.15-1.25 microg mL(-1). Sensitivity indices such as molar absorptivity, limits of detection and quantification are reported. Intra-day and inter-day precision, and accuracy of the methods were established according to the ICH guidelines, and the er values were in the range of -1.7 to 1.8% with RSD values ranging from 1.0 to 1.1%. The method was successfully applied to the assay of PFM in tablet preparations with recoveries varying from 97.5 to 101.9%, with standard deviation in the range of 0.6 to 1.9. The results were statistically compared with those of the reference method by applying Student's t-test and F-test. Accuracy evaluated by means of the spike recovery method, range from 97.0 to 106.0%, with precision better than 3%. PMID:17507318

Basavaiah, Kanakapura; Prameela, Hullikal Chandrashekar; Somashekar, Bankavadi Chikkaswamy

2007-06-01

387

Spectrophotometric Determination of Cobalt with Di2-Pyridyl Ketone Benzoylhydrazone  

Microsoft Academic Search

A method for the spectrophotometric determination of cobalt (II) by complexation with di-2-pyridyl ketone benzoylhydrazone (DPKBH) in 50% (v\\/v) ethanolic solution is described. Cobalt (II) forms a 1:2 complex with DPKBH. The complex has maximum absorbance at 370 nm. Beer's law is obeyed over the range 0.1 – 2.8 ?g.ml. The effect of pH, effect of excess reagent, stability of

Nidal A. Zatar; Mohammed A. Al-Nuri; Maher Abu-Eid; Mohammed Hannoun; All Z. Abu-Zuhri; Shukri Khalaf; Mustafa Khamis

1991-01-01

388

Spectrophotometric Estimation of Carbaryl Residue in Some Home Garden Vegetables  

Microsoft Academic Search

Residues of carbaryl (1-Naphthyl N-methly carbamate) were determined in the fruit and foliage of seven home garden vegetables by a spectrophotometric method. Residues at harvest averaged the following levels; cabbage (head, 0.0 ppm), cucumber (foliage 0.0 ppm; fruit, 0.05 ppm), garden bush beans (fruit, 0.0 ppm), Okra (foliage, 0.0 ppm; fruit, 0.01 ppm), pepper (foliage, 2.72 ppm; fruit, 0.9 ppm),

Nand K. Narain; V. E. Melchor; C. C. Lewis; R. D. Irwin; M. A. Latheef

1978-01-01

389

Derivative spectrophotometric and fluorimetric methods for determination of rofecoxib in tablets and in human plasma in presence of its photo-degradation product.  

PubMed

Rofecoxib (I) has been determined in the presence of its photo-degradation product (II) using first derivative spectrophotometry ((1)D) and first derivative of the ratio spectra ((1)DD) by measuring the amplitude at 316.3 and 284 nm for (1)D and (1)DD, respectively. (I) can be determined in the presence of up to 70% and 80% of (II) by the (1)D and (1)DD, respectively. The linearity range of both the methods was the same (5.8-26.2 microg ml(-1)) with mean percentage recovery of 100.08 +/- 0.84 and 100.06 +/- 1.06 for (1)D and (1)DD, respectively. (1)D method was used to study kinetics of (I) photo-degradation that was found to follow a first-order reaction. The t(1/2) was 20.2 min while K (reaction rate constant) was 0.0336 mol min(-1). Both methods were applied to the analysis of (I) in bulk powder and in pharmaceutical formulations. Also a spectrofluorimetric method is described to determine (I) at very low concentrations (25-540 ng ml(-1)) where (I) is converted to its photo-degradate (II), which possesses a native fluorescence that could be measured. The proposed method was applied for the analysis of tablets containing rofecoxib as well as to rofecoxib-spiked human plasma. PMID:14871506

Shehata, Mostafa A; Hassan, Nagiba Y; Fayed, Ahmad S; El-Zeany, Badr A

2004-02-01

390

First and second derivative synchronous fluorescence and spectrophotometric spectroscopy for the simultaneous determination of fexofenadine hydrochloride in presence of its degradation products. Application to stability studies.  

PubMed

Two rapid, simple, sensitive, selective and economic derivative spectrophotometric (first [D1] and second [D2]) and synchronous spectrofluorimetric (FDSFS and SDSFS) methods have been developed for the analysis of fexofenadine hydrochloride (FXD) in the presence of its different degradation products. Derivative spectrophotometry (D1) was used to measure FXD at 223 nm in the presence of its alkaline or acidic degradation products, and at 211 nm in the presence of its oxidative degradation product. Derivative spectrophotometry (D2) was used to determine FXD at 217 nm in the presence of its alkaline or acidic degradation products, and at 215 nm in the presence of its oxidative degradation product; the UV degradation product was measured at 211 nm. Synchronous spectrofluorimetry (FDSFS) was used to measure FXD in the presence of its alkaline or acidic degradation products at 406 nm, and at 367 nm in the presence of its oxidative or UV degradation products. Synchronous spectrofluorimetry (SDSFS) was applied to determine the drug at 225 nm in the presence of its alkaline, acidic, oxidative or UV degradation products. The proposed methods were successfully applied for the determination of the studied compound in its commercial tablets. The results obtained were in good agreement with those obtained by the comparison method. PMID:24062038

El-Din, Mohie Khaled Sharaf; Ibrahim, Fawzia Ahmed; Eid, Manal Ibrahim; Wahba, Mary Elias Kamel

2011-06-01

391

Ion-pair spectrophotometric estimation of gemifloxacin  

PubMed Central

Introduction: The main objective was to develop and validate a simple, accurate, precise, and sensitive ion-pair spectrophotometric extraction method for the assay of gemifloxacin mesylate (GFX) in pure, tablets and spiked human urine. Materials and Methods: The method is based upon the reaction of gemifloxacin with methyl orange, forming a yellow-colored complex in acidic medium, which is extracted in chloroform and analyzed. The extracted complexes showed absorbance maxima (?max) found to be at 427 nm. Results: Beer's law was obeyed for a wide concentration range, i.e., 10–80 ?g/ mL as the extracted species seemed well defined and stable. The surface or an interphase adsorption phenomenon was not a problem. Optimization of the reaction was carried out with factors such as buffer strength, stability of complex, and molar ratio of drug: Dye and extraction time. The proposed method was validated as per the ICH guidelines. The recovery studies confirmed the accuracy and precision of the method. Conclusion: The above-mentioned method was a rapid tool for routine analysis of GFX in the bulk and pharmaceutical dosage forms.

Sahu, Satyabrata; Patro, Saroj Kumar; Narayan, Una Laxmi; Garnaik, Bamakanta

2012-01-01

392

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

393

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

394

HPLC-Methode zur Bestimmung von vitamin C in Milch, Molke und Molkegetränken  

Microsoft Academic Search

Summary A method is described for the estimation ofl-ascorbic acid andl-dehydroascorbic acid in milk, whey, and whey drinks by paired-ion reversed-phase HPLC using a C18-column.l-ascorbic acid is detected UV-spectrophotometrically at 248 nm,l-dehydroascorbic acid is determined spectrofluorometrically with excitation at 350 nm and emission at 430 nm, after derivatisation into a quinoxaline fluorophor.

Wolfgang Kneifel; Regina Sommer

1985-01-01

395

Characteristics and Performance of the Sunna High Dose Dosemeter Using Green Photoluminescence and UV Absorption Readout Methods  

SciTech Connect

Growth in the use of ionizing radiation for medical sterilization and the potential for wide-scale international food irradiation have created the need for robust, mass-producible, inexpensive, and highly accurate radiation dosemeters. The Sunna dosemeter, lithium fluoride injection-moulded in a polyethylene matrix, can be read out using either green photoluminescence or ultraviolet (UV) absorption.

Miller, Steven D.; Murphy, Mark K.; Tinker, Mike R.; Kovacs, Andres; Mclaughlin, William

2002-01-01

396

Application of Box-Wilson experimental design method for the photodegradation of bakery's yeast industry with UV/H2O2 and UV/H2O2/Fe(II) process.  

PubMed

Decolorization and mineralization of bakery's yeast industry effluent by photochemical advanced oxidation processes (AOPs) utilizing UV with hydrogen peroxide and Photo-Fenton, were investigated in a laboratory scale photo-reactor equipped with a 16 W low-pressure mercury vapor lamp. The Box-Wilson experimental design method was employed to evaluate the effects of major process variables (e.g. pH, oxidant dose, and irradiation time) on the decolorization efficiency. Response function coefficients were determined by regression analysis of the experimental data and prediction results agreed with the experimental results. The optimum hydrogen peroxide concentration and irradiation time were found to be 5 mM and 50 min at pH 3, respectively, for UV/H2O2 process. In the Photo-Fenton process application, maximum decolorization efficiency (96.4%) was obtained at the optimum reaction conditions that were 100 mM H2O2 and 1 mM Fe(II) doses at pH 3, and 10 min of irradiation time. PMID:16162392

Catalkaya, Ebru C; Sengül, Füsun

2005-09-12

397

Development of a method for the determination of UV filters in water samples using stir bar sorptive extraction and thermal desorption-gas chromatography-mass spectrometry.  

PubMed

Stir bar sorptive extraction (SBSE) in combination with thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) was applied for the determination of 9 UV filters in water samples. The stir bar coated with polydimethylsiloxane (PDMS) was added to 20 mL of water sample at pH 2 (10% MeOH) and stirred at 1000 rpm for 180 min. Then, the stir bar was subjected to TD-GC-MS. The desorption conditions (desorption temperature and desorption time) and SBSE parameters (ionic strength, pH, presence of organic solvent and time) were optimised using a full factorial design and a Box-Behnken design, respectively. The method shows good linearity (correlation coefficients >0.994) and reproducibility (RSD<16%). The extraction efficiencies were above 63% for all the compounds. Detection limits were between 0.2 and 63 ng/L. The developed method offers the ability to detect several UV filters at ultra-low concentration levels with only 20 mL of sample volume. The effectiveness of the method was tested by analysing real samples such as lake water, river water and treated wastewater. The application of the method allowed reporting the levels of UV filters in environmental water samples. PMID:18096171

Rodil, Rosario; Moeder, Monika

2007-12-04

398

Kinetic spectrophotometric determination of Fe(II) in the presence of Fe(III) by H-point standard addition method in mixed micellar medium  

NASA Astrophysics Data System (ADS)

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 Triton X-100 micellar medium. Fe(II) can be determined in the range 0.25-2.5 ?g ml -1 with satisfactory accuracy and precision in the presence of excess Fe(III) and other metal ions that rapidly form complexes with MTB under working condition. The proposed method was successfully applied to the simultaneous determination of Fe(II) and Fe(III) or selective determination of Fe(II) in the presence of Fe(III) in spiked real environmental and synthetic samples with complex composition.

Hasani, Masoumeh; Rezaei, Alireza; Abdollahi, Hamid

2007-11-01

399

In-situ spectrophotometric probe  

DOEpatents

A spectrophotometric probe for in situ absorption spectra measurements comprising a first optical fiber carrying light from a remote light source, a second optical fiber carrying light to a remote spectrophotometer, the proximal ends of the first and second optical fibers parallel and coterminal, a planoconvex lens to collimate light from the first optical fiber, a reflecting grid positioned a short distance from the lens to reflect the collimated light back to the lens for focussing on the second optical fiber. The lens is positioned with the convex side toward the optical fibers. A substrate for absorbing analyte or an analyte and reagent mixture may be positioned between the lens and the reflecting grid.

Prather, William S. (2419 Dickey Rd., Augusta, GA 30906)

1992-01-01

400

Development and Validation of Analytical Method for Fluconazole and Fluconazole Related Compounds (A, B, and C) in Capsule Formulations by HPLC with UV Detection  

Microsoft Academic Search

A simple and stability-indicating liquid chromatographic method was developed and validated for the analysis of Fluconazole and its related compound (A, B, and C) in capsule formulations. Liquid chromatography with a UV detector at a wavelength of 260 nm using a reversed-phase C18 column was employed in this study. Isocratic elution was employed using a mixture of methanol and water

F. Al-Rimawi

2009-01-01

401

Spectrophotometric determination of zirconium with xylenol orange  

SciTech Connect

High purity hydride forming metal films are used as hydrogen isotope occluders and function as electrodes in neutron generator tubes. This use of zirconium occluder films requires reliable analytical methods for routine determination of the zirconium film weight in a production environment. In this study, a spectrophotometric method was evaluated for the determination of zirconium films. The method is based upon the formation of a highly colored zirconium complex with xylenol orange in a dilute perchloric acid medium. Dilute hydrofluoric acid is used in this procedure to selectively dissolve the zirconium film off the substrate. A perchloric acid fuming step is used to remove hydrofluoric acid from the solution. The zirconium solutions are depolymerized before complex formation by heating in 2 N perchloric acid. The zirconium complex exhibits a maximum absorbance in 0.2 to 0.3 M perchloric acid at a wavelength of 531 nanometers. Beer's law is obeyed for zirconium concentrations through 2.1 parts per million. Molybdenum, at concentrations equal to zirconium, does not interfere with the xylenol orange method.

Antepenko, R.J.

1982-05-14

402

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.

403

Effect of UV irradiation on detection of cocaine hydrochloride and crack vapors by IMIS and API-MS methods.  

PubMed

Detection of drug vapors and volatile products of their decomposition is an important, and sometimes the only way to determine the presence of illegal drug traces at the surface of mail items, documents, hands and banknotes. This paper gives the results of experimental studies on the effect of UV irradiation on the sensitivity of a vapor phase detection of cocaine of different origin by a technology of ion mobility increment spectrometry (IMIS). It is shown that the influence of UV irradiation on the surface of cocaine hydrochloride and crack increases the amplitude of IMIS signals by about eight times. We analyzed ions emerged by photolysis of tested cocaine samples using mass-spectrometry with atmospheric pressure ionization (API-MS). The assumption is made about structural formula of volatile products of photolysis of crack and cocaine hydrochloride. By the results of API-MS and IMIS studies on photolysis of cocaine samples it is assumed that compound C(10)H(15)NO(3) with a molecular weight of 197 amu and ecgonidine methyl ester with a molecular weight of 181 amu are responsible for the increase of an amplitude of IMIS signals upon UV irradiation of samples of crack and cocaine hydrochloride. PMID:19203621

Kolomiets, Yuri N; Pervukhin, Viktor V

2008-12-11

404

Aqueous-Phase Synthesis of Silver Nanodiscs and Nanorods in Methyl Cellulose Matrix: Photophysical Study and Simulation of UV-Vis Extinction Spectra Using DDA Method  

PubMed Central

We present a very simple and effective way for the synthesis of tunable coloured silver sols having different morphologies. The procedure is based on the seed-mediated growth approach where methyl cellulose (MC) has been used as soft-template in the growth solution. Nanostructures of varying morphologies as well as colour of the silver sols are controlled by altering the concentration of citrate in the growth solution. Similar to the polymers in the solution, citrate ions also dynamically adsorbed on the growing silver nanoparticles and promote one (1-D) and two-dimensional (2-D) growth of nanoparticles. Silver nanostructures are characterized using UV–vis and HR-TEM spectroscopic study. Simulation of the UV–vis extinction spectra of our synthesized silver nanostructures has been carried out using discrete dipole approximation (DDA) method.

2010-01-01

405

Photometric Method for the Quantification of Chlorophylls and Their Derivatives in Complex Mixtures: Fitting with Gauss-Peak Spectra  

Microsoft Academic Search

Accurate quantification of pigments in mixtures is essential in all cases in which separation of pigments by chromatography is impracticable for one reason or another. An example is the analysis of in vivo formation of heavy metal-substituted chlorophylls in heavy metal-stressed plants. We describe here a novel, accurate UV\\/VIS spectrophotometric method for the quantification of individual chlorophyll derivatives in complex

Hendrik Küpper; Martin Spiller; Frithjof C. Kupper

2000-01-01

406

[Spectrophotometric and gas chromatographic analysis of trichloroacetic acid in urine].  

PubMed

Some chlorinated hydrocarbon solvents--1,1,1-trichloroethane, trichloroethylene and perchloroethylene--have a common biotransformation product, trichloroacetic acid, which can be used as their biological exposure index. The spectrophotometric and gas chromatographic methods for the determination of trichloroacetic acid were studied and used as well as in its determination in the urine of workers exposed to 1,1,1-trichloroethane. Both methods showed good precision and no statistically significant difference was found although the gas chromatographic method presented a lower detection limit. PMID:9110472

Pedrozo, M de F; Siqueira, M E

1996-06-01

407

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

408

Systematic mutagenesis method for enhanced production of bacitracin by Bacillus licheniformis Mutant Strain UV-MN-HN-6.  

PubMed

The purpose of the current study was intended to obtain the enhanced production of bacitracin by Bacillus licheniformis through random mutagenesis and optimization of various parameters. Several isolates of Bacillus licheniformis were isolated from local habitat and isolate designated as GP-35 produced maximum bacitracin production (14±0.72 IU ml(-1)). Bacitracin production of Bacillus licheniformis GP-35 was increased to 23±0.69 IU ml(-1) after treatment with ultraviolet (UV) radiations. Similarly, treatment of vegetative cells of GP-35 with chemicals like N-methyl N'-nitro N-nitroso guanidine (MNNG) and Nitrous acid (HNO2) increased the bacitracin production to a level of 31±1.35 IU ml(-1) and 27±0.89 IU ml(-1)respectively. Treatment of isolate GP-35 with combined effect of UV and chemical treatment yield significantly higher titers of bacitracin with maximum bacitracin production of 41.6±0.92 IU ml(-1). Production of bacitracin was further enhanced (59.1±1.35 IU ml(-1)) by optimization of different parameters like phosphate sources, organic acids as well as temperature and pH. An increase of 4.22 fold in the production of bacitracin after mutagenesis and optimization of various parameters was achieved in comparison to wild type. Mutant strain was highly stable and produced consistent yield of bacitracin even after 15 generations. On the basis of kinetic variables, notably Yp/s (IU/g substrate), Yp/x (IU/g cells), Yx/s(g/g), Yp/s, mutant strain B. licheniformis UV-MN-HN-6 was found to be a hyperproducer of bacitracin. PMID:24031806

Aftab, Muhammad Nauman; Ikram-Ul-Haq; Baig, Shahjahan

2012-06-01

409

Systematic mutagenesis method for enhanced production of bacitracin by Bacillus licheniformis Mutant Strain UV-MN-HN-6  

PubMed Central

The purpose of the current study was intended to obtain the enhanced production of bacitracin by Bacillus licheniformis through random mutagenesis and optimization of various parameters. Several isolates of Bacillus licheniformis were isolated from local habitat and isolate designated as GP-35 produced maximum bacitracin production (14±0.72 IU ml-1). Bacitracin production of Bacillus licheniformis GP-35 was increased to 23±0.69 IU ml-1 after treatment with ultraviolet (UV) radiations. Similarly, treatment of vegetative cells of GP-35 with chemicals like N-methyl N’-nitro N-nitroso guanidine (MNNG) and Nitrous acid (HNO2) increased the bacitracin production to a level of 31±1.35 IU ml-1 and 27±0.89 IU ml-1respectively. Treatment of isolate GP-35 with combined effect of UV and chemical treatment yield significantly higher titers of bacitracin with maximum bacitracin production of 41.6±0.92 IU ml-1. Production of bacitracin was further enhanced (59.1±1.35 IU ml-1) by optimization of different parameters like phosphate sources, organic acids as well as temperature and pH. An increase of 4.22 fold in the production of bacitracin after mutagenesis and optimization of various parameters was achieved in comparison to wild type. Mutant strain was highly stable and produced consistent yield of bacitracin even after 15 generations. On the basis of kinetic variables, notably Yp/s (IU/g substrate), Yp/x (IU/g cells), Yx/s(g/g), Yp/s, mutant strain B. licheniformis UV-MN-HN-6 was found to be a hyperproducer of bacitracin.

Aftab, Muhammad Nauman; Ikram-ul-Haq; Baig, Shahjahan

2012-01-01

410

Response surface method for the optimisation of micropollutant removal in municipal wastewater treatment plant effluent with the UV/H2O2 advanced oxidation process.  

PubMed

Experiments with the ultraviolet (UV)/H2O2 advanced oxidation process (AOP) were conducted to investigate the abatement of micropollutants in wastewater treatment plant effluent. The fluence and the starting concentration of H2O2 in a bench-scale batch reactor were varied according to response surface method (RSM) to examine their influence on the treatment efficiency. It was shown that the investigated AOP is very effective for the abatement of micropollutants with conversion rates typically higher than 90%. Empirical relationships between fluence, H2O2 dosage and the resulting concentration of micropollutants were established by RSM. By this means it was shown that X-ray-contrast media had been degraded only by UV light. Nevertheless, most substances were degraded by the combination of UV irradiation and H2O2. Based on RSM an optimisation of multiple responses was conducted to find the minimal fluence and H2O2 dosage that are needed to reach an efficient abatement of micropollutants. PMID:23656952

Schulze-Hennings, U; Pinnekamp, J

2013-01-01

411

Spectrophotometric determination of phosphorus acid  

SciTech Connect

A number of procedures have been proposed to determine phosphorus acid and its salts, the phosphites, in the presence of hypophosphorus acid and its salts, the hypophosphites. Among these procedures, iodometric back-titration has produced the most reliable results. In this paper, the authors propose an improved iodometric determination of phosphorus acid that enables the sensitivity to be increased by at least two orders of magnitude. The essence of this improvement is that excess iodine that did not react with phosphite ion is determined not volumetrically but spectrophotometrically. To eliminate the effect of iodine ion that is liberated when iodine reacts with phosphite ion on the optical density of the solution, a 200-fold excess of potassium iodide is added before the photometric measurement. The working iodine solution is prepared by diluting 10 m of 0.025 N iodine titrant and 50 ml of phosphate buffer, pH 6.7-7.2, to 1 liter with distilled water in a coulometric flask. To construct the calibration curve, 5, 10, 15, 20, and 25 ml, respectively of working iodine solution, and 10 ml of 2% aqueous potassium iodide are placed into five 100-ml volumetric flasks, and the solutions are made up to volume with water. After 10 min the photometric measurements are carried out at 380 nm using curvets and the reference solution is obtained by diluting 10 ml of 2% aqueous potassium iodide to 100 ml with distilled water.

Domin, A.V.; Domina, N.G.; Zakharov, Yu.A.; Shechkov, G.T.

1987-03-01

412

Variable path length spectrophotometric probe  

DOEpatents

This invention consists of a compact, variable pathlength, fiber optic probe for spectrophotometric measurements of fluids in situ . The probe comprises a probe body with a shaft having a polished end penetrating one side of the probe, a pair of optic fibers, parallel and coterminous, entering the probe opposite the reflecting shaft, and a collimating lens to direct light from one of the fibers to the reflecting surface of the shaft and to direct the reflected light to the second optic fiber. The probe body has an inlet and an outlet port to allow the liquid to enter the probe body and pass between the lens and the reflecting surface of the shaft. A linear stepper motor is connected to the shaft to cause the shaft to advance toward or away from the lens in increments so that absorption measurements can be made at each of the incremental steps. The shaft is sealed to the probe body by a bellows seal to allow freedom of movement of the shaft and yet avoid leakage from the interior of the probe.

O`Rourke, P.E.; McCarty, J.E.; Haggard, R.A.

1991-12-31

413

Variable path length spectrophotometric probe  

DOEpatents

This invention consists of a compact, variable pathlength, fiber optic probe for spectrophotometric measurements of fluids in situ . The probe comprises a probe body with a shaft having a polished end penetrating one side of the probe, a pair of optic fibers, parallel and coterminous, entering the probe opposite the reflecting shaft, and a collimating lens to direct light from one of the fibers to the reflecting surface of the shaft and to direct the reflected light to the second optic fiber. The probe body has an inlet and an outlet port to allow the liquid to enter the probe body and pass between the lens and the reflecting surface of the shaft. A linear stepper motor is connected to the shaft to cause the shaft to advance toward or away from the lens in increments so that absorption measurements can be made at each of the incremental steps. The shaft is sealed to the probe body by a bellows seal to allow freedom of movement of the shaft and yet avoid leakage from the interior of the probe.

O' Rourke, P.E.; McCarty, J.E.; Haggard, R.A.

1991-01-01

414

Spectrophotometric determination of carbamazepine and mosapride citrate in pure and pharmaceutical preparations  

Microsoft Academic Search

Simple, rapid and sensitive spectrophotometric methods were developed for the determination of carbamazepine and mosapride citrate drugs in pure and pharmaceutical dosage forms. These methods are based on ion pair and charge transfer complexation reactions. The first method is based on the reaction of the carbamazepine drug with Mo(V)–thiocyanate in hydrochloric acid medium followed by an extraction of the coloured

Eman Y. Z. Frag; M. A. Zayed; M. M. Omar; Sally E. A. Elashery; Gehad G. Mohamed

415

An ultraviolet spectrophotometric assay for aspartate transcarbamylase.  

PubMed

A procedure for determining the activity of aspartate transcarbamylase, based upon the greater ultraviolet absorbancy of the products of the reaction catalyzed compared to the reactants, was devised. Extinction coefficients were determined at 205, 210, and 215 nm for the compounds carbamoyl aspartate, acetyl aspartate, and aspartate. These values formed the quantitative basis for a spectrophotometric assay in which an enzymatic reaction is monitored at one of these wavelengths. Use of this procedure was illustrated in four kinetic experiments with the allosteric aspartate transcarbamylase from Escherichia coli, and the nonallosteric catalytic subunit of this enzyme: aspartate saturation curve, arsenate saturation curve (reverse reaction), allosteric activation by a transition-state analog employing acetyl phosphate as substrate, and carbamoyl phosphate progress curve (substrate depletion in the presence of excess cosubstrate). Owing to changes in absorbance on the order of 1000 liter mol-1 cm-1 concomitant with the reaction, the sensitivity of the method is comparable to that of many procedures already in the literature. PMID:6359955

Foote, J

1983-10-15

416

Spectrophotometric determination of channel black in small arms propellants.  

PubMed

A spectrophotometric method is proposed for the determination of Channel Black in small arms propellants. The Channel Black is separated from the nitrocellulose and other organic compounds by dissolution of the propellant in morpholine and filtration through a sintered porcelain crucible containing an asbestos mat. The Channel Black is then dissolved by treating the mat and crucible with boiling nitric acid for 3 hr, the solution is filtered, and the yellow colour is measured. The colour is due to polycarboxylic acids with cyclic nuclei. The range of the method is from 0 to 0.5% of Channel Black. PMID:18960138

Galan, M; Norwitz, G

1967-05-01

417

Simultaneous spectrophotometric estimation of imipramine hydrochloride and chlordiazepoxide in tablets.  

PubMed

A binary mixture of imipramine HCl and chlordiazepoxide was determined by three different spectrophotometric methods. The first method involved determination of imipramine HCl and chlordiazepoxide using the simultaneous equations and the second method involved absorbance ratio method. Imipramine has absorbance maxima at 251 nm, chlordiazepoxide has absorbance maxima at 264.5 nm and isoabsorptive point is at 220 nm in methanol. Linearity was obtained in the concentration ranges of 1-25 and 1-10 mug/ml for Imipramine HCL and Chlordiazepoxide, respectively. The third method involved determination of these two drugs using the first-derivative spectrophotometric technique at 219 and 231.5 nm over the concentration ranges of 1-20 and 2-24 mug/ml with mean accuracies 99.46+/-0.78 and 101.43+/-1.20%, respectively. These methods were successively applied to pharmaceutical formulations because no interferences from the tablet excipients were found. The suitability of these methods for the quantitative determination of the compounds was proved by validation. PMID:20502561

Patel, Sejal; Patel, N J; Patel, S A

2009-07-01

418

Simultaneous Spectrophotometric Estimation of Imipramine Hydrochloride and Chlordiazepoxide in Tablets  

PubMed Central

A binary mixture of imipramine HCl and chlordiazepoxide was determined by three different spectrophotometric methods. The first method involved determination of imipramine HCl and chlordiazepoxide using the simultaneous equations and the second method involved absorbance ratio method. Imipramine has absorbance maxima at 251 nm, chlordiazepoxide has absorbance maxima at 264.5 nm and isoabsorptive point is at 220 nm in methanol. Linearity was obtained in the concentration ranges of 1-25 and 1-10 ?g/ml for Imipramine HCL and Chlordiazepoxide, respectively. The third method involved determination of these two drugs using the first-derivative spectrophotometric technique at 219 and 231.5 nm over the concentration ranges of 1-20 and 2-24 ?g/ml with mean accuracies 99.46±0.78 and 101.43±1.20%, respectively. These methods were successively applied to pharmaceutical formulations because no interferences from the tablet excipients were found. The suitability of these methods for the quantitative determination of the compounds was proved by validation.

Patel, Sejal; Patel, N. J.; Patel, S. A.

2009-01-01

419

Kinetic Spectrophotometric Determination of Fluvastatin in Pharmaceutical Preparations  

PubMed Central

Simple, accurate and reliable kinetic spectrophotometric method for the determination of fluvastatin sodium (FVS) in pure form and pharmaceutical formulations has been described. The method is based on the formation of colored product between FVS and 4-chloro-7-nitrobenzofurazan (NBD-Cl) in acetone medium at 55 ± 2ºC. The reaction is followed spectrophotometrically by measuring the increase in absorbance at 462 nm as a function of time. The rate data and fixed time methods were adopted for constructing the calibration curves. The linearity ranges were found to be 15.0–50.0 and 10.0–90.0 ?g mL?1 for rate data and fixed time methods, respectively. The limit of detection for rate data and fixed time methods is 0.017 and 0.134 ?g mL?1, respectively. The proposed methods have been successfully applied to the determination of fluvastatin sodium in pharmaceutical dosage forms with no interference from the excipients. Statistical comparison of the results shows that there is no significant difference between the proposed and official methods.

Ashour, Safwan; Bahbouh, Mahmoud; Khateeb, Mouhammed

2010-01-01

420

Structural study of polymer hydrogel contact lenses by means of positron annihilation lifetime spectroscopy and UV-vis-NIR methods.  

PubMed

A study has been conducted in order to determine presence of free volume gaps in the structure of structure of polymer hydrogel contact lenses made in phosphoryl choline technology and of the degree of defect of its structure. The study was made by means of positron annihilation lifetime spectroscopy. As a result of the conducted measurements, curves were obtained, which described numbers of counts of the acts of annihilation in the time function. The conducted studies revealed existence of three components ?(1), ?(2) and ?(3). The ?(3) component is attributed to the pick-off annihilation of o-Ps orthopositronium trapping by free volume gaps and provides information about geometrical parameters of the volumes. At the same time, the UV-vis-NIR spectrometry examination was conducted on the same samples in the spectral range 200-1,000 nm. PMID:23695358

Filipecki, J; Kocela, A; Korzekwa, P; Miedzinski, R; Filipecka, K; Golis, E; Korzekwa, W

2013-05-22

421

Preparation of superhydrophobic and UV blocking cotton fabric via sol–gel method and self-assembly  

NASA Astrophysics Data System (ADS)

Superhydrophobic surface has been successfully prepared on cotton substrates with inexpensive and ordinary raw materials, Al(NO3)3 and sodium stearate (C17H35COONa). Such surfaces were obtained first by dip-coating the nano-Al sol, then the surface of the Al coating was modified with sodium stearate, to gain a thin film through self-assembly. Th