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1

Determination of adamantane derivatives in pharmaceutical formulations by using spectrophotometric UV-Vis method.  

PubMed

A simple and sensitive extractive spectrophotometric method have been developed and validated for determination of amantadine hydrochloride (AM), memantine hydrochloride (MM) and rimantadine hydrochloride (RM) in pure and pharmaceutical formulations. The method is based on the reaction of these active compounds with bromophenol blue (BB) in acetate buffer (0.1 M) pH 3.5 to form an orange-colored products which have absorption maxima at 408 nm. The procedure of complexation was optimized with regard to such factors as concentrations of BB, pH of medium, a kind of extracting solvents and a number of extractions. Under the optimum conditions, linear relationships A408 = f(c) with good correlation coefficients (?0.996) and low limit of detection were obtained in the ranges of 50.0-220.0 gmL(-1), 20.0-150.0 gmL(-1) or 10.0-110.0 gmL(-1) for AM, MM and RM, respectively, for the spectrophotometric methods. The proposed method could be applied to the determination of AM, MM and RM in dosage forms. The recovery was 95.3-101.9%. The method was linear, precise and accurate. PMID:22568696

Sobczak, Agnieszka; Muszalska, Izabela; Rohowska, Paulina; Inerowicz, Tomasz; Dotka, Hubert; Jeli?ska, Anna

2013-05-01

2

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

3

UVvis spectrophotometric method for the quantitation of all the components of Italian general denaturant and its application to check the conformity of alcohol samples  

Microsoft Academic Search

A simple, fast and relatively inexpensive spectrophotometric method for the identification and the quantification of the individual components of the Italian general denaturant in alcohol samples is proposed.In particular, it is shown that bitrex (a quaternary ammonium salt), whose UV spectrum is completely masked by those of the other denaturant components, can be identified using its reaction with disulphine blue

Remo Bucci; Fabrizio Balestrieri; Andrea D. Magr; Antonio L. Magr; Federico Marini

2006-01-01

4

New, simple, and validated UV-spectrophotometric method for the estimation of some beta blockers in bulk and formulations  

Microsoft Academic Search

A sensitive, extraction, derivatization, evaporation and complexation-free, direct spectrophotometric method is developed\\u000a for the determination of some anthypertensive drugs such as acebutolol hydrochloride (ACH), atenolol (ATE), and propranolol hydrochloride (PRH) in bulk and pharmaceutical formulations. The optimum conditions for the analysis of aqua solutions of drugs are established.\\u000a The method permits the determination of ACH, ATE, and PRH over a

Ay?egl Glc

2008-01-01

5

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

PubMed Central

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

Muralidharan, Selvadurai; Meyyanathan, Subramania Nainar

2011-01-01

6

Multivariate calibrations in UV spectrophotometric analysis.  

PubMed

Calibration allows the user to relate instrumental measurements to the sample of interest. Multivariate calibration allows for the analysis of several measurements from several samples or specimens. The method contributes to the two steps procedure where step one involves the calibration of data and second step involves the prediction that are made or based on the calibration. In calibration, indirect measurements are made from samples where the amount of the analyte has been predetermined, usually by an independent assay or technique. These measurements, along with the predetermined analyte levels, comprise a group known as the calibration set. This set is used to develop a model that relates the amount of sample to the measurements by the instrument. In some cases, the construction of the model is simple due to a certain relationship, such as Beer's Law in the application of UV spectroscopy. Unlike spectroscopy, other cases can be much more complex, and it is in these cases where construction of the model is time-consuming step. Once the model is constructed, it can predict analyte levels based on measurements of new samples. It can be used to separate samples from interferences without the need of highly selective measurements for the analyte. Calibration techniques (used in the calibration step) differ in determining coefficient values for the preceding or similar equations. PMID:17416574

Arayne, M Saeed; Sultana, Najma; Bahadur, Saima Sher

2007-04-01

7

UV-spectrophotometric determination of glycyrrhizic acid in Glycyrrhiza glabra  

Microsoft Academic Search

SummaryA spectrophotometric method for determining glycyrrhizic acid in a thick licorice extract, dry licorice powder, and licorice\\u000a roots after its chromatographic separation from the accompanying substances in a thin layer of sorbent has been proposed.\\u000a The limit of detection of glycyrrhizic acid is 8 g\\/ml. The concentration of glycyrrhizic acid in the thick extracts is ?15.49%,\\u000a in the dry powder

M. R. Yakubova; G. L. Genkina; T. T. Shakirov

1977-01-01

8

Spectrophotometric method for analysis of metformin hydrochloride.  

PubMed

A simple and sensitive spectrophotometric method has been developed and validated for the estimation of metformin hydrochloride in bulk and in tablet formulation. The primary amino group of metformin hydrochloride reacts with ninhydrin in alkaline medium to form a violet colour chromogen, which is determined spectrophotometrically at 570 nm. It obeyed Beer's law in the range of 8-18 mug/ml. Percentage recovery of the drug for the proposed method ranged from 97-100% indicating no interference of the tablet excipients. The proposed method was found to be accurate and precise for routine estimation of metformin hydrochloride in bulk and from tablet dosage forms. PMID:20177473

Mubeen, G; Noor, Khalikha

2009-01-01

9

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

PubMed

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

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

2014-01-01

10

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

PubMed Central

The application of first-order derivative and wavelet transforms to UV spectra and ratio spectra was proposed for the simultaneous determination of ibuprofen and paracetamol in their combined tablets. A new hybrid approach on the combined use of first-order derivative and wavelet transforms to spectra was also discussed. In this application, DWT (sym6 and haar), CWT (mexh), and FWT were optimized to give the highest spectral recoveries. Calibration graphs in the linear concentration ranges of ibuprofen (1232?mg/L) and paracetamol (2040?mg/L) were obtained by measuring the amplitudes of the transformed signals. Our proposed spectrophotometric methods were statistically compared to HPLC in terms of precision and accuracy. PMID:24949492

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

2014-01-01

11

Dual potentiometric and UV\\/Vis spectrophotometric disposable sensors with dispersion cast polyaniline  

Microsoft Academic Search

Simple conducting polymerpolyaniline-based sensors\\/biosensors, working either in potentiometric or UV\\/Vis spectrophotometric\\u000a mode, are proposed. Disposable sensors were produced by coating polyaniline layers, cast from aqueous dispersion of the polymer\\u000a nanoparticles, on a transparent plastic polyacetate foil. In the potentiometric mode, polyaniline layers are sensitive to\\u000a a number of metal cations, while in UV\\/Vis mode, changes of absorbance were recorded only

Pawe? Malinowski; Iwona Grzegrz?ka; Agata Michalska; Krzysztof Maksymiuk

2010-01-01

12

Determination of some antioxidants by derivative spectrophotometric method and high-performance liquid chromatography  

Microsoft Academic Search

The UV-derivative spectrophotometric method was used for assaying butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and propyl gallate (PG) in pure state and in laboratory mixtures. Ir; this paper the results are presented using zero-crdssing technique. In this way, thc interference of two components mixed together has been eliminated. That is the greatest advantage of derivative spectroscopy compared with the classical

D. Ivanovic; E. Guernet-nivaud; M. Guernet

1990-01-01

13

Development and validation of column high-performance liquid chromatographic and ultraviolet spectrophotometric methods for citalopram in tablets.  

PubMed

Column high-performance liquid chromatographic (LC) and UV spectrophotometric methods for the quantitative determination of citalopram, a potent and selective serotonin reuptake inhibitor, in tablets were developed. The parameters linearity, precision, accuracy, specificity, robustness, limit of detection, and limit of quantitation were studied according to International Conference on Harmonization guidelines. Chromatography was carried out by the reversed-phase technique on an ACE C18 column with a mobile phase composed of 0.30% triethylamine solution-acetonitrile (55 + 45, v/v) adjusted to pH 6.6 with 10% ortho-phosphoric acid at a flow rate of 1.0 mL/min and 25 degrees C. The UV spectrophotometric method was performed at 239 nm. The linearity of the LC method was in the range of 10.00-70.00 microg/mL, and 2.50-17.50 microg/mL for the UV spectrophotometric method. The interday and intraday assay precision was < 1.5% (relative standard deviation) for the LC and UV spectrophotometric methods. The recoveries were in the range 100.70-101.35% for the LC method and 98.48-98.65% for the UV spectrophotometric method. Statistical analysis by Student's t-test showed no significant difference between the results obtained by the 2 methods. The proposed methods are highly sensitive, precise, and accurate and can be used for the reliable quantitation of citalopram in tablets. PMID:18376585

Menegola, Jlia; Steppe, Martin; Schapoval, Elfrides E S

2008-01-01

14

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.d250 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. PMID:20582208

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

2010-01-01

15

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

16

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

PubMed Central

A simple, sensitive, cost-effective and reproducible UV-spectrophotometric method has been developed and validated for the estimation of disodium edetate in topical gel formulations. Solution of disodium edetate reacts with ferric chloride to form complex in 0.1 N HCl giving ?max at 270 nm. Beer's law was obeyed in the concentration range of 550 ?g/mL (r2= 0.9997). The limit of detection and limit of quantitation were found to be 1.190 and 3.608 ?g/mL, respectively. The results show that the procedure is accurate, precise, and reproducible (relative standard deviation < 1%), while being simple and less time consuming. The study concluded that the UV-spectrophotometric method could be used for the quantification of disodium edetate in pure form as well as in pharmaceutical formulations. PMID:23781446

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

2011-01-01

17

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

PubMed

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

Abdelaleem, Eglal Adelhamid; Abdelwahab, Nada Sayed

2013-01-01

18

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. PMID:23781491

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

2012-01-01

19

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

PubMed

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

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

2014-01-01

20

Spectrophotometric determination of aqueous cyanide using a revised phenolphthalin method.  

PubMed

This paper focuses on a revision of the phenolphthalin method for cyanide analysis, with the intent of producing a robust and sensitive spectrophotometric method. Limitations of the phenolphthalin chemistry were overcome by the addition of EDTA to the reagent. The revised reagent was found to have suitably fast kinetics, a linear dynamic range of 0.01-3.0 ppm cyanide, and a detection limit of 5 ppb. The method was tested for interferences and applied to the determination of cyanide in environmental waters. PMID:17397664

Cacace, David; Ashbaugh, Heidi; Kouri, Naomi; Bledsoe, Sara; Lancaster, Sean; Chalk, Stuart

2007-04-18

21

Validated spectrophotometric and spectrofluorimetric methods for determination of chloroaluminum phthalocyanine in nanocarriers.  

PubMed

UV-VIS-Spectrophotometric and spectrofluorimetric methods have been developed and validated allowing the quantification of chloroaluminum phthalocyanine (CIAIPc) in nanocarriers. In order to validate the methods, the linearity, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy, and selectivity were examined according to USP 30 and ICH guidelines. Linearities range were found between 0.50-3.00 microg x mL(-1) (Y = 0.3829 X [CIAIPc, microg x mL(-1)] + 0.0126; r = 0.9992) for spectrophotometry, and 0.05-1.00 microg x mL(-1) (Y = 2.24 x 10(6) X [CIAIPc, microg x mL(-1)] + 9.74 x 10(4); r = 0.9978) for spectrofluorimetry. In addition, ANOVA and Lack-of-fit tests demonstrated that the regression equations were statistically significant (p<0.05), and the resulting linear model is fully adequate for both analytical methods. The LOD values were 0.09 and 0.01 microg x mL(-1), while the LOQ were 0.27 and 0.04 microg x mL(-1) for spectrophotometric and spectrofluorimetric methods, respectively. Repeatability and intermediate precision for proposed methods showed relative standard deviation (RSD) between 0.58% to 4.80%. The percent recovery ranged from 98.9% to 102.7% for spectrophotometric analyses and from 94.2% to 101.2% for spectrofluorimetry. No interferences from common excipients were detected and both methods were considered specific. Therefore, the methods are accurate, precise, specific, and reproducible and hence can be applied for quantification of CIAIPc in nanoemulsions (NE) and nanocapsules (NC). PMID:20187572

Siqueira-Moura, M P; Primo, F L; Peti, A P F; Tedesco, A C

2010-01-01

22

Spectrophotometric methods for the determination of Ibuprofen in tablets.  

PubMed

Ibuprofen in film coated tablets of different strengths has been determined using different spectrophotometric methods. These are: (i) the compensation method, (ii) a two wavelengths method, (iii) second-order and (iv) fourth-order derivative methods, and (v) a curve fitting method based upon computing the quadratic coefficient of the orthogonal polynomials expansion of its benzenoid absorption characteristics. All results were compared with the HPLC method of the B.P. 2003 using paired comparison. Developed methods have been validated and applied to different tablet formulations. Mean differences from the B.P. method were found to be -0.10, -0.30, -0.10, -0.16, -0.34%, respectively. In view of the relatively low specific absorbance of ibuprofen in the ultraviolet region [A (1%, 1 cm) =18.5 at 264 nm] its accurate and precise determination in different tablet formulations is challenging due to the presence of interferences from excipients. PMID:16380350

Wahbi, Abdel Aziz; Hassan, Ekram; Hamdy, Dalia; Khamis, Essam; Barary, Magda

2005-10-01

23

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

24

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 1.016 ?g ml1 with correlation coefficient (n=6) ?0.9991. The molar absorpitivity, Sandell sensitivity, detection, and quantification limits were also calculated. The composition of the ion pairs was found 1:1 by Job's method. The proposed methods have been applied successfully for the analysis of TPC in pure and in its eye drops. PMID:22523460

Shoaibi, ZA; Gouda, AA

2012-01-01

25

Validated spectrophotometric methods for determination of some oral hypoglycemic drugs.  

PubMed

Four accurate, precise, rapid, reproducible, and simple spectrophotometric methods were validated for determination of repaglinide (RPG), pioglitazone hydrochloride (PGL) and rosiglitazone maleate (RGL). The first two methods were based on the formation of a charge-transfer purple-colored complex of chloranilic acid with RPG and RGL with a molar absorptivity 1.23 103 and 8.67 102 lmol-1cm-1 and a Sandell's sensitivity of 0.367 and 0.412 ?gcm-2, respectively, and an ion-pair yellow-colored complex of bromophenol blue with RPG, PGL and RGL with molar absorptivity 8.86 103, 6.95 103, and 7.06 103 lmol-1cm-1, respectively, and a Sandell's sensitivity of 0.051 ?gcm-2 for all ion-pair complexes. The influence of different parameters on color formation was studied to determine optimum conditions for the visible spectrophotometric methods. The other spectrophotometric methods were adopted for demtermination of the studied drugs in the presence of their acid-, alkaline- and oxidative-degradates by computing derivative and pH-induced difference spectrophotometry, as stability-indicating techniques. All the proposed methods were validated according to the International Conference on Harmonization guidelines and successfully applied for determination of the studied drugs in pure form and in pharmaceutical preparations with good extraction recovery ranges between 98.7-101.4%, 98.2-101.3%, and 99.9-101.4% for RPG, PGL, and RGL, respectively. Results of relative standard deviations did not exceed 1.6%, indicating that the proposed methods having good repeatability and reproducibility. All the obtained results were statistically compared to the official method used for RPG analysis and the manufacturers methods used for PGL and RGL analysis, respectively, where no significant differences were found. PMID:22466095

Farouk, M; Abdel-Satar, O; Abdel-Aziz, O; Shaaban, M

2011-02-01

26

[Spectrophotometric method for the determination of water in organic solvents].  

PubMed

In the presence of a small amount of water, the chloranilic acid was disassociated. The absorption peak was bathochromic-shifted and the absorption intensity dramatically enhanced. Based on this fact, a spectrophotometric method was developed for determining water in many kinds of organic solvents. The mechanism and conditions for the determination were studied thoroughly. The water in alcohol samples (white wine, food alcohol and reagent alcohol) was detected with satisfactory results. The method was simple, sensitive and of good reproducibility. The linear range was phi(H2O) 0.02%-10% in alcohol. The method was also used for the determination of water in other organic solvents such as methanol, 2-propanol, acetone, butanone, acetonitrile and tetrahydrofuran, and the calibration curves were obtained, respectively. PMID:15768994

Li, Gui-zhi; Liu, Yong-ming

2004-01-01

27

Sensitive spectrophotometric method for trace amounts of uranium.  

PubMed

A sensitive spectrophotometric method for the determination of uranium with Pyrogallol Red (PGR) and cetyltrimethylammonium bromide (CTAB) is described. The sensitivity of the colour reaction between uranium and Pyrogallol Red is greatly increased in the presence of cetyltrimethylammonium bromide. The blue ternary complex (lambda(max)580 nm) has composition 1:2:4 [U(VI):PGR:CTAB] at pH 5.6. Beer's law is obeyed over the range 19.0-0.24 ppm of uranium and the molar absorptivity is 3.3 x 10(4) l.mole(-1).cm(-1) at 620 nm. A tentative structure for the ternary complex is suggested. A simple method is suggested for evaluation of stability constants of such ternary complexes. PMID:18962595

Prakash, O; Kumar, S; Mushran, S P

1979-12-01

28

Spectrophotometric estimation of tamsulosin hydrochloride by acid-dye method.  

PubMed

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

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

2011-01-01

29

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

30

Building up a database of spectro-photometric standard stars from the UV to the near-IR: a status report!  

E-print Network

Building up a database of spectro-photometric standard stars from the UV to the near-IR: a status. Currently no such set of standard stars covering the near-IR is available. Our strategy is to extend the useful range of existing well-established optical flux standards into the near-IR by means of integral

Liske, Jochen

31

Simultaneous spectrophotometric determination of atrazine and cyanazine by chemometric methods  

NASA Astrophysics Data System (ADS)

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

Zhang, Guowen; Pan, Junhui

2011-01-01

32

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

33

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

PubMed

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

Rastegarzadeh, Saadat; Pourreza, Nahid; Larki, Arash

2013-10-01

34

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 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 and 1600 ) 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 . 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 . 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 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.; Lpez Ariste, A.; Wang, S.

2007-10-01

35

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

2007-01-01

36

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

PubMed

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

Youssef, Nadia F

2003-01-01

37

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 4400ngmL?1

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

2008-01-01

38

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

PubMed

New, simple, specific, accurate, precise and reproducible spectrophotometric methods have been developed and subsequently validated for determination of vildagliptin (VLG) and metformin (MET) in binary mixture. Zero order spectrophotometric method was the first method used for determination of MET in the range of 2-12 ?g mL(-1) by measuring the absorbance at 237.6 nm. The second method was derivative spectrophotometric technique; utilized for determination of MET at 247.4 nm, in the range of 1-12 ?g mL(-1). Derivative ratio spectrophotometric method was the third technique; used for determination of VLG in the range of 4-24 ?g mL(-1) at 265.8 nm. Fourth and fifth methods adopted for determination of VLG in the range of 4-24 ?g mL(-1); were ratio subtraction and mean centering spectrophotometric methods, respectively. All the results were statistically compared with the reported methods, using one-way analysis of variance (ANOVA). The developed methods were satisfactorily applied to analysis of the investigated drugs and proved to be specific and accurate for quality control of them in pharmaceutical dosage forms. PMID:24548810

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

2014-05-01

39

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

NASA Astrophysics Data System (ADS)

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

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

40

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

41

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 g/ml (r=0.9991) for losratan pottassium, 2 - 12 g/ml (r = 0.9995) for atenolol and 2 - 14 g/ml (r = 0.9993) for hydrochlorothiazide. The results of the method were validated statistically and by recovery studies. PMID:21180476

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

2010-01-01

42

Five different spectrophotometric methods for determination of Amprolium hydrochloride and Ethopabate binary mixture.  

PubMed

Five simple, specific, accurate and precise UV-spectrophotometric methods are adopted for the simultaneous determination of Amprolium hydrochloride (AMP) and Ethopabate (ETH), a binary mixture with overlapping spectra, without preliminary separation. The first method is first derivative of the ratio spectra ((1)DD) for determination of AMP and ETH at 234.7nm and 306.8nm respectively with mean percentage recoveries 99.760.907 and 100.290.842 respectively. The second method is the mean centering of the ratio spectra for determination of AMP and ETH at 238.8nm and 313nm respectively with mean percentage recoveries 100.261.018 and 99.941.286 respectively. The third method is based on dual wavelength selection for determination of AMP and ETH at 235.3nm & 308nm and 244nm & 268.4nm respectively with mean percentage recoveries 99.301.097 and 100.031.065 respectively. The fourth method is ratio difference method for determination of AMP and ETH at 239nm & 310nm and 239nm & 313nm respectively with mean percentage recoveries 99.270.892 and 100.401.814 respectively. The fifth one is area under the curve (AUC) method where the areas between 235.6-243nm and 268.3-275nm are selected for determination of AMP and ETH with mean percentage recoveries 100.351.031 and 100.390.956 respectively. These methods are tested by analyzing synthetic mixtures of the two drugs and they are applied to their pharmaceutical veterinary preparation. Methods are validated according to the ICH guidelines and accuracy, precision and repeatability are found to be within the acceptable limit. PMID:25523045

Hussein, Lobna A; Magdy, N; Abbas, Mahmoud M

2015-03-01

43

New Sensitive Kinetic Spectrophotometric Methods for Determination of Omeprazole in Dosage Forms  

PubMed Central

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 1H-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 0.103.00 and 0.5025.00??g?mL?1 with the lowest LOD of 0.03 and 0.14??g?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 98.91100.32% 0.941.84, and was found to be comparable with that of reference method. PMID:20140076

Mahmoud, Ashraf M.

2009-01-01

44

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

45

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

46

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

NASA Astrophysics Data System (ADS)

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

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

2007-10-01

47

Validated spectrophotometric and fluorimetric methods for analysis of clozapine in tablets and urine.  

PubMed

Five spectrophotometric methods and one fluorimetric method have been developed and validated for the analysis of clozapine. The spectrophotometric methods were based on the charge-transfer complexation reaction between clozapine as electron donor and each of iodine as sigma-acceptor or 7,7,8,8-tetracyanoquinondimethane (TCNQ), 2,3-dichloro-5,6-dicyano-1,4-benzo-quinone (DDQ), tetracyanoethane (TCNE), and p-chloranilic acid (pCA) as pi-acceptors. The obtained complexes were measured spectrophotometrically at 365, 843, 460, 414, and 520 nm for iodine, TCNQ, DDQ, TCNE, and pCA, respectively. The fluorimetric method was based on the oxidation of clozapine in the presence of perchloric acid by cerium (IV), and subsequent measuring the fluorescence of the produced cerium (III) fluorimetrically at lambda(excitation) 260 and lambda(emission) 355 nm. Under the optimum assay conditions, Beer's law was obeyed at concentrations ranged from 4-200 microg mL(-1) for the spectrophotometric methods and from 24-250 ng mL(-1) for the fluorimetric method. The limits of detection for the spectrophotometric methods were 1.12, 1.76, 2.22, 0.95, and 13.26 microg mL(-1) for iodine, TCNQ, DDQ, TCNE, and pCA, respectively. The limit of detection for the fluorimetric method was 6.69 ng mL(-1). The proposed methods were successfully applied to the analysis of clozapine in tablets with good recoveries. The fluorimetric method could also be applied to the analysis of clozapine in spiked urine samples. The molar ratios and the reaction mechanisms were investigated. PMID:16477942

Darwish, Ibrahim; Abdel-Wadood, Hanaa; Abdel-Latif, Niveen

2005-05-01

48

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

NASA Astrophysics Data System (ADS)

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

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

49

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

PubMed

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

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

2015-04-01

50

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

PubMed

A new spectrophotometric method for the determination of trace amounts of bisphenol A based on a diazotization-coupling reaction was developed. In acidic solution, clenbuterol was first diazotized with sodium nitrite, then coupled with bisphenol A to from an azo-compound [I] in NH3-NH4Cl buffer, which shows a maximum absorption at 410 nm. The effects of the amount of sodium nitrite, diazo reaction time, the amount of clenbuterol, coupling reaction time and coupling reaction temperature have been examined. Under the optional conditions, the determination of the linear range of bisphenol A is 0.24-8.4 ?g/mL, correlation coefficient is 0.9905 and detection limit of this method is 0.15 ?g/mL. The spectrophotometric method is simple, rapid, high sensitivity with better accuracy. High performance liquid chromatography (HPLC) technique combined with this new spectrophotometric method has been also developed for the measurement of bisphenol A. The analysis was achieved on a C18 column using water and methanol as a mobile phase and the detection was done spectrophotometrically at 410 nm. These reported methods were applied to the determination of bisphenol A in hot water in contact with commercially available table-water bottle samples. PMID:24309176

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

2014-03-25

51

Simultaneous spectrofluorimetric and spectrophotometric determination of melatonin and pyridoxine in pharmaceutical preparations by multivariate calibration methods.  

PubMed

Partial least-squares (PLS) calibration and principal component regression (PCR) methods were utilized for the simultaneous spectrofluorimetric and spectrophotometric determination of pyridoxine (PY) and melatonin (MT). Since emission and adsorption spectra of these drugs overlap, PY and MT cannot be directly determined by fluorimetric nor by spectrophotometric methods. Full-spectrum multivariate calibration PLS and PCR methods were developed for both fluorimetry and spectrophotometry. The conditions were optimized for fluorimetric as well as for spectrophotometric determination of both drugs. The simultaneous determination of PY and MT was carried out in mixtures by recording the emission fluorescence spectrum between 324 and 500 nm (lambda(ex) 285 nm) for fluorimetry, and by recording the absorption spectrum between 250 and 350 nm for spectrophotometry (lambda(max(PY)) 310 nm, lambda(max(MT)) 278 nm). The experimental calibration matrixes were designed orthogonally. At the optimum conditions, dynamic ranges were 0.04-1.3 and 0.1-4 microg ml(-1) for fluorimetry and 1-22 and 1-24 microg ml(-1) for spectrophotometry for MT and PY, respectively. The calibration concentrations were prepared in the dynamic ranges. The parameters of the chemometrics procedure for the simultaneous determination of MT and PY were optimized, and the proposed methods were validated with prediction set. Finally the procedures were successfully applied to simultaneous spectrofluorimetric and spectrophotometric determination of PY and MT in synthetic mixtures and in a pharmaceutical formulation. PMID:15885688

Sorouraddin, Mohammad-Hussein; Rashidi, Mohammad-Reza; Ghorbani-Kalhor, Ebrahim; Asadpour-Zeynali, Karim

2005-05-01

52

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

NASA Astrophysics Data System (ADS)

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

Purcell, Dale Kevin

53

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

54

Comparison of three new spectrophotometric methods for simultaneous determination of aspirin and salicylic acid in tablets without separation of pharmaceutical excipients.  

PubMed

Simultaneous analysis of aspirin (ASA) and salicylic acid (SA) in pharmaceutical tablet preparations was performed by two multicomponent UV-spectrophotometric methods utilizing principal component regression and classical least square algorithm. Additionally, an assay procedure based on second-derivative spectroscopy was developed. The analysis was performed in turbid solutions without separation of interfering excipients. The range, as determined by the second-derivative methods, was 0.2 to 103.2 micrograms/mL for ASA and 0.07 to 44.5 micrograms/mL for SA. Sensitivity for determination of SA was 0.004% of ASA content for the second-derivative method and 0.2% of ASA content for both multicomponent methods. The methods were applied to laboratory mixtures and commercial tablet formulations containing ASA and SA. The advantage of the second-derivative method in determining small amounts of SA in commercial tablet preparations is shown in comparison with a conventional HPLC method. All UV-spectrophotometric methods are rapid, accurate, and reproducible. PMID:8071834

Glombitza, B W; Schmidt, P C

1994-05-01

55

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

Microsoft Academic Search

A new kinetic spectrophotometric method has been developed for the determination of iron (III). The method is based on the\\u000a 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\\u000a under room temperature

Hongwei Ji; Jian Xu; Huizhen Xin; Xiaoman Yang

2008-01-01

56

Rapid, sensitive, iron-based spectrophotometric methods for determination of peroxide values of food lipids.  

PubMed

The official International Dairy Federation method for determination of the peroxide value of anhydrous milk fat was extended to poultry, meat, fish, and vegetable oils. The ferrous oxidation-xylenol orange method for determination of peroxide values of liposomes and lipoproteins was modified to make it simpler and more rapid. These 2 spectrophotometric methods were used successfully to determine the peroxide values of beef, chicken, butter, fish, and vegetable products. The results in most cases were consistent with those obtained by using the AOAC Official Method. The spectrophotometric methods have an assay time of less than 10 min, require < or = 0.3 g fat, and are capable of determining peroxide values as low as 0.1 mequiv/kg of sample. PMID:8199478

Shantha, N C; Decker, E A

1994-01-01

57

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. PMID:23781481

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

2012-01-01

58

Optimized and validated spectrophotometric method for the determination of uranium(VI) via complexation with meloxicam.  

PubMed

An optimized and validated spectrophotometric method has been developed for the determination of uranyl ion in the presence of other metal ions. The method is based on the chelation of uranyl ion with meloxicam via beta-diketone moiety to produce a yellow colored complex, which absorbs maximally at 398 nm. Beer's law is obeyed in the concentration range of 5-60 microg/mL with apparent molar absorptivity and Sandell's sensitivity of 5.02 x 10(4)L/mol/cm and 0.1 microg/cm2/0.001 absorbance unit, respectively. The method has been successfully applied for the determination of uranyl ion in synthetic mixture and soil samples. Results of analysis were statistically compared with those obtained by Currah's spectrophotometric method showing acceptable recovery and precision. PMID:18164125

Lutfullah; Alam, Mohd Noor; Rahman, Nafisur; Azmi, Syed Najmul Hejaz

2008-06-30

59

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

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

60

A Continuous Spectrophotometric Method for Determining the Monophenolase and Diphenolase Activities of Apple Polyphenol Oxidase  

Microsoft Academic Search

A continuous spectrophotometric method for the determination of the monophenolase and diphenolase activities of apple polyphenol oxidase is described. The method is based on the coupling reaction between 3-methyl-2-benzothiazolinone hydrazone (MBTH) and the quinone product of the oxidation of p-hydroxyphenyl propionic acid and 3,4-dihydroxyphenyl propionic acid in the presence of polyphenol oxidase. The ?max and the molar absorptivity (?) for

J. C. Espin; M. Morales; R. Varon; J. Tudela; F. Garciacanovas

1995-01-01

61

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

Microsoft Academic Search

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

S. M. Al-Ghannam

2006-01-01

62

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

Microsoft Academic Search

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

Lata Cherian; V. K. Gupta

1991-01-01

63

Spectrophotometric Method for the Rapid Determination of Microgram Amounts of Ethionamide  

Microsoft Academic Search

Spectrophotometric Method for the Rapid Determination of Microgram Amounts of EthionamideA simple and sensitive method for the determination of microgram amounts of ethionamide is described. Ethionamide is converted to corresponding 2-ethyl-?-pyridyl thiohydroxamic acid which gives a purple violet colour (?max 510 nm) with ferric chloride in acidic medium. This forms the basis for the quantitative determination of ethionamide in its

A. K. Shah; Y. K. Agrawal; S. K. Banerjee

1981-01-01

64

SIMULTANEOUS DETERMINATION OF ACTIVE INGREDIENTS IN BINARY MIXTURES CONTAINING CAFFEINE USING LIQUID CHROMATOGRAPHIC AND SPECTROPHOTOMETRIC METHODS  

Microsoft Academic Search

Two new spectrophotometric methods are described for the simultaneous determination of caf- feine, aspirin and propyphenazone in binary mixtures containing caffeine without prior separation procedure. In the first method, ratio spectra derivative spectrophotometry, the signals were measured at 254.3 nm for caffeine and at 220.0 nm for aspirin in caffeine - aspirin mixture and at 215.6 nm for caffeine and

Erdal Din; Filiz Yurtsever; Feyyaz Onur

65

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

66

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

67

Two smart spectrophotometric methods for the simultaneous estimation of Simvastatin and Ezetimibe in combined dosage form  

NASA Astrophysics Data System (ADS)

Two simple, accurate, precise, sensitive and economic spectrophotometric methods were developed for the simultaneous determination of Simvastatin and Ezetimibe in fixed dose combination products without prior separation. The first method depends on a new chemometrics-assisted ratio spectra derivative method using moving window polynomial least square fitting method (Savitzky-Golay filters). The second method is based on a simple modification for the ratio subtraction method. The suggested methods were validated according to USP guidelines and can be applied for routine quality control testing.

Magdy, Nancy; Ayad, Miriam F.

2015-02-01

68

A simple and very sensitive spectrophotometric method for the direct determination of copper ions  

Microsoft Academic Search

A sensitive spectrophotometric method for the direct determination of copper in aqueous samples without a preconcentration step has been developed. It is based on the formation of a yellow complex with the chromogenic reagent di-2-pyridyl ketone benzoylhydrazone (dPKBH) in an alkaline medium. The complex stoichiometry was 1:2 (Cu:dPKBH) and presents maximum absorbance at 370 nm. The influence of chemical variables

Juan J. Pinto; Carlos Moreno; Manuel Garca-Vargas

2002-01-01

69

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

PubMed

Two new, sensitive and selective spectrofluorimetric and spectrophotometric methods have been developed for the determination of the gamma-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 determination of pregabalin in capsules were developed for the first time. The relation between the absorbance at 460 nm and the concentration is rectilinear over the range 0.5-7.0 microg mL(-1). The reaction product was also measured spectrofluorimetrically at 558 nm after excitation at 460 nm. The fluorescence intensity was directly proportional to the concentration over the range 40-400 ng mL(-1). The method was applied successfully to the determination of this drug in pharmaceutical dosage form. The mean recovery for the commercial capsules was 99.93% and 99.96% for spectrophotometric and spectrofluorimetric study, respectively. The suggested procedures could be used for the determination of PGB in pure and capsules being sensitive, simple and selective. PMID:18922737

Onal, Arma?an; Sagirli, Olcay

2009-02-01

70

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

NASA Astrophysics Data System (ADS)

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 determination of pregabalin in capsules were developed for the first time. The relation between the absorbance at 460 nm and the concentration is rectilinear over the range 0.5-7.0 ?g mL -1. The reaction product was also measured spectrofluorimetrically at 558 nm after excitation at 460 nm. The fluorescence intensity was directly proportional to the concentration over the range 40-400 ng mL -1. The method was applied successfully to the determination of this drug in pharmaceutical dosage form. The mean recovery for the commercial capsules was 99.93% and 99.96% for spectrophotometric and spectrofluorimetric study, respectively. The suggested procedures could be used for the determination of PGB in pure and capsules being sensitive, simple and selective.

nal, Arma?an; Sagirli, Olcay

2009-02-01

71

Novel two wavelength spectrophotometric methods for simultaneous determination of binary mixtures with severely overlapping spectra.  

PubMed

This work presents the application of different spectrophotometric techniques based on two wavelengths for the determination of severely overlapped spectral components in a binary mixture without prior separation. Four novel spectrophotometric methods were developed namely: induced dual wavelength method (IDW), dual wavelength resolution technique (DWRT), advanced amplitude modulation method (AAM) and induced amplitude modulation method (IAM). The results of the novel methods were compared to that of three well-established methods which were: dual wavelength method (DW), Vierordt's method (VD) and bivariate method (BV). The developed methods were applied for the analysis of the binary mixture of hydrocortisone acetate (HCA) and fusidic acid (FSA) formulated as topical cream accompanied by the determination of methyl paraben and propyl paraben present as preservatives. The specificity of the novel methods was investigated by analyzing laboratory prepared mixtures and the combined dosage form. The methods were validated as per ICH guidelines where accuracy, repeatability, inter-day precision and robustness were found to be within the acceptable limits. The results obtained from the proposed methods were statistically compared with official ones where no significant difference was observed. No difference was observed between the obtained results when compared to the reported HPLC method, which proved that the developed methods could be alternative to HPLC techniques in quality control laboratories. PMID:25467671

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

2014-10-31

72

Novel two wavelength spectrophotometric methods for simultaneous determination of binary mixtures with severely overlapping spectra  

NASA Astrophysics Data System (ADS)

This work presents the application of different spectrophotometric techniques based on two wavelengths for the determination of severely overlapped spectral components in a binary mixture without prior separation. Four novel spectrophotometric methods were developed namely: induced dual wavelength method (IDW), dual wavelength resolution technique (DWRT), advanced amplitude modulation method (AAM) and induced amplitude modulation method (IAM). The results of the novel methods were compared to that of three well-established methods which were: dual wavelength method (DW), Vierordt's method (VD) and bivariate method (BV). The developed methods were applied for the analysis of the binary mixture of hydrocortisone acetate (HCA) and fusidic acid (FSA) formulated as topical cream accompanied by the determination of methyl paraben and propyl paraben present as preservatives. The specificity of the novel methods was investigated by analyzing laboratory prepared mixtures and the combined dosage form. The methods were validated as per ICH guidelines where accuracy, repeatability, inter-day precision and robustness were found to be within the acceptable limits. The results obtained from the proposed methods were statistically compared with official ones where no significant difference was observed. No difference was observed between the obtained results when compared to the reported HPLC method, which proved that the developed methods could be alternative to HPLC techniques in quality control laboratories.

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

2015-02-01

73

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

PubMed

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

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

2013-11-01

74

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

PubMed Central

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

2012-01-01

75

Spectrophotometric determination of ziram (dithiocarbamate fungicide) by thiocyanate and rhodamine 6G method.  

PubMed

A sensitive spectrophotometric method has been developed for the determination of ziram in water, vegetables and grains. The method is based on the dissociation of dithiocarbamate complex of zinc with thiocyanate and rhodamine 6G at pH 4 to form a pink coloured complex that is stabilized by gelatin. The method is simple and Beer's law is obeyed over the concentration range of 0.05-1 ppm of ziram. The method is free from interference of similar dithiocarbamate fungicides containing Mn(2+) and Fe(3+) ions. PMID:18966197

Mathew, L; Rao, T P; Iyer, C S; Damodaran, A D

1995-01-01

76

Simultaneous determination of a binary mixture of pantoprazole sodium and itopride hydrochloride by four spectrophotometric methods  

NASA Astrophysics Data System (ADS)

Four simple, sensitive, accurate and precise spectrophotometric methods were developed for the simultaneous determination of a binary mixture containing Pantoprazole Sodium Sesquihydrate (PAN) and Itopride Hydrochloride (ITH). Method (A) is the derivative ratio method (1DD), method (B) is the mean centering of ratio spectra method (MCR), method (C) is the ratio difference method (RD) and method (D) is the isoabsorptive point coupled with third derivative method (3D). Linear correlation was obtained in range 8-44 ?g/mL for PAN by the four proposed methods, 8-40 ?g/mL for ITH by methods A, B and C and 10-40 ?g/mL for ITH by method D. The suggested methods were validated according to ICH guidelines. The obtained results were statistically compared with those obtained by the official and a reported method for PAN and ITH, respectively, showing no significant difference with respect to accuracy and precision.

Ramadan, Nesrin K.; El-Ragehy, Nariman A.; Ragab, Mona T.; El-Zeany, Badr A.

2015-02-01

77

Simultaneous determination of a binary mixture of pantoprazole sodium and itopride hydrochloride by four spectrophotometric methods.  

PubMed

Four simple, sensitive, accurate and precise spectrophotometric methods were developed for the simultaneous determination of a binary mixture containing Pantoprazole Sodium Sesquihydrate (PAN) and Itopride Hydrochloride (ITH). Method (A) is the derivative ratio method ((1)DD), method (B) is the mean centering of ratio spectra method (MCR), method (C) is the ratio difference method (RD) and method (D) is the isoabsorptive point coupled with third derivative method ((3)D). Linear correlation was obtained in range 8-44?g/mL for PAN by the four proposed methods, 8-40?g/mL for ITH by methods A, B and C and 10-40?g/mL for ITH by method D. The suggested methods were validated according to ICH guidelines. The obtained results were statistically compared with those obtained by the official and a reported method for PAN and ITH, respectively, showing no significant difference with respect to accuracy and precision. PMID:25238185

Ramadan, Nesrin K; El-Ragehy, Nariman A; Ragab, Mona T; El-Zeany, Badr A

2015-02-25

78

Evaluation of sealing ability of MM-MTA, Endosequence, and biodentine as furcation repair materials: UV spectrophotometric analysis  

PubMed Central

Aim: To evaluate the sealing ability of MICRO-MEGA Mineral Trioxide Aggregate, Endosequence, Biodentine as furcation repair materials using a dye extraction leakage method. Materials and Methods: Forty mandibular molars were randomly divided according to the material used for perforation repair. Group I- (left unsealed) control, Group II-MICRO-MEGA Mineral Trioxide Aggregate, Group III - Endosequence, Group IV - Biodentine. All samples were subjected to orthograde and retrograde methylene blue dye challenge followed by dye extraction with 65% nitric acid. Samples were then analyzed using Ultra violet (UV) Visible Spectrophotometer. Results: Biodentine showed highest dye absorbance, whereas Endosequence showed lowest dye absorbance when compared with other repair materials. Conclusion: Within the limitations of this study, it was observed that Endosequence showed better sealing ability when compared with other root repair materials. PMID:25125846

Jeevani, Eppala; Jayaprakash, Thumu; Bolla, Nagesh; Vemuri, Sayesh; Sunil, Chukka Ram; Kalluru, Rama S

2014-01-01

79

Quantitative determination of zopiclone and its impurity by four different spectrophotometric methods  

NASA Astrophysics Data System (ADS)

Four simple, sensitive and selective spectrophotometric methods are presented for determination of Zopiclone (ZPC) and its impurity, one of its degradation products, namely; 2-amino-5-chloropyridine (ACP). Method A is a dual wavelength spectrophotometry; where two wavelengths (252 and 301 nm for ZPC, and 238 and 261 nm for ACP) were selected for each component in such a way that difference in absorbance is zero for the second one. Method B is isoabsorptive ratio method by combining the isoabsorptive point (259.8 nm) in the ratio spectrum using ACP as a divisor and the ratio difference for a single step determination of both components. Method C is third derivative (D3) spectrophotometric method which allows determination of both ZPC at 283.6 nm and ACP at 251.6 nm without interference of each other. Method D is based on measuring the peak amplitude of the first derivative of the ratio spectra (DD1) at 263.2 nm for ZPC and 252 nm for ACP. The suggested methods were validated according to ICH guidelines and can be applied for routine analysis in quality control laboratories. Statistical analysis of the results obtained from the proposed methods and those obtained from the reported method has been carried out revealing high accuracy and good precision.

Abdelrahman, Maha M.; Naguib, Ibrahim A.; El Ghobashy, Mohamed R.; Ali, Nesma A.

2015-02-01

80

Quantitative determination of zopiclone and its impurity by four different spectrophotometric methods.  

PubMed

Four simple, sensitive and selective spectrophotometric methods are presented for determination of Zopiclone (ZPC) and its impurity, one of its degradation products, namely; 2-amino-5-chloropyridine (ACP). Method A is a dual wavelength spectrophotometry; where two wavelengths (252 and 301nm for ZPC, and 238 and 261nm for ACP) were selected for each component in such a way that difference in absorbance is zero for the second one. Method B is isoabsorptive ratio method by combining the isoabsorptive point (259.8nm) in the ratio spectrum using ACP as a divisor and the ratio difference for a single step determination of both components. Method C is third derivative (D(3)) spectrophotometric method which allows determination of both ZPC at 283.6nm and ACP at 251.6nm without interference of each other. Method D is based on measuring the peak amplitude of the first derivative of the ratio spectra (DD(1)) at 263.2nm for ZPC and 252nm for ACP. The suggested methods were validated according to ICH guidelines and can be applied for routine analysis in quality control laboratories. Statistical analysis of the results obtained from the proposed methods and those obtained from the reported method has been carried out revealing high accuracy and good precision. PMID:25244295

Abdelrahman, Maha M; Naguib, Ibrahim A; El Ghobashy, Mohamed R; Ali, Nesma A

2015-02-25

81

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

PubMed

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

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

2014-05-01

82

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

NASA Astrophysics Data System (ADS)

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

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

83

Spectrophotometric and spectrofluorimetric methods for the determination of ramipril in its pure and dosage form  

NASA Astrophysics Data System (ADS)

This paper describes three sensitive spectrophotometric and spectrofluorimetric methods for determination of ramipril in its pure form and pharmaceutical tablets. The first method is based on the oxidation of the drug with 1-chlorobenzotriazole reagent (CBT) in strong alkaline medium followed by measuring the absorbance at 350 nm. The method obeys Beer's law over concentration range 15-50 ?g ml -1. For the second and third, both are non-extractive methods based on the formation of ternary complex between copper (II), eosin and ramipril in the presence of methylcellulose as surfactant. Spectrophotometrically, under the optimum condition, the ternary complex showed an absorption maximum at 543 nm. The method obeys Beer's law over concentration range of 20-80 ?g ml -1. A fluorescence quenching method for the determination of ramipril by forming this ternary complex was also investigated for the propose of enhance the sensitivity of the determination. The methods are simple, sensitive, and accurate. The results obtained are reproducible with a coefficient of variation less than 2%. The proposed have been successfully applied to the assay of ramipril in tablets. The results compare favorably with official method.

Abdellatef, Hisham E.

2007-03-01

84

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 g/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. PMID:21264107

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

2010-01-01

85

Zero order spectrophotometric method for estimation of escitalopram oxalate in tablet formulations.  

PubMed

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 g/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. PMID:21264107

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

2010-10-01

86

Spectrophotometric method for exploring 3-methyl-2-butene-1-thiol (MBT) formation in lager.  

PubMed

The disappearance of riboflavin absorbance at 445 nm from beers or model beers on light exposure is directly linked to light-struck character formation. The addition of (+)-catechin, (-)-epicatechin, tryptophol, or ascorbic acid was able to reduce, but not stop, absorbance loss or light-struck character formation in either model beer or mainstream lager that was exposed to light. When isohumulone was present in model beer, the inhibitory effect of (+)-catechin, (-)-epicatechin, or tryptophol decreased with increasing isohumulone. The spectrophotometric method used in this study is a simple and effective method for determining light-struck susceptibility. PMID:16910696

Pozdrik, Richard; Roddick, Felicity A; Rogers, Peter J; Nguyen, Thang

2006-08-23

87

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

PubMed Central

One titrimetric and two spectrophotometric methods are described for the determination of ketotifen fumarate (KTF) in bulk drug and in tablets using cerium(IV) as the oxidimetric agent. In titrimetry (method A), the drug was treated with a measured excess of cerium(IV) in H2SO4 medium and after a standing time of 10 min, the surplus oxidant was determined by back titration with iron(II). The spectrophotometric procedures involve addition of a known excess of cerium(IV) to KTF in acid medium followed by the determination of unreacted oxidant by reacting with either p-dimethyl amino benzaldehyde and measuring the resulting colour at 460?nm (method B) or o-dianisidine and subsequent measurement of the absorbance of coloured product at 470?nm (method C). Titrimetric assay is based on a 1?:?2 reaction stoichiometry between KTF and cerium(IV) and the method is applicable over 218?mg range. In spectrophotometry, regression analysis of Beer's law plots showed a good correlation in 0.48.0 and 0.410.0?g?mL?1 KTF ranges for method B and method C, respectively, and the corresponding molar absorptivity coefficients are calculated to be 4.0 104 and 3.7 104?L?mol?1?cm?1. PMID:24324496

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

2013-01-01

88

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, Mickal; Lpez-Giraldo, Luis J; Lecomte, Jrme; Bara, Bruno; Cambon, Emmanuelle; Tchobo, Paul Fidle; Barouh, Nathalie; Villeneuve, Pierre

2008-09-15

89

A novel method for spectrophotometric determination of pregabalin in pure form and in capsules  

PubMed Central

Background Pregabalin, a ?-amino-n-butyric acid derivative, is an antiepileptic drug not yet official in any pharmacopeia and development of analytical procedures for this drug in bulk/formulation forms is a necessity. We herein, report a new, simple, extraction free, cost effective, sensitive and reproducible spectrophotometric method for the determination of the pregabalin. Results Pregabalin, as a primary amine was reacted with ninhydrin in phosphate buffer pH 7.4 to form blue violet colored chromogen which could be measured spectrophotometrically at ?max 402.6 nm. The method was validated with respect to linearity, accuracy, precision and robustness. The method showed linearity in a wide concentration range of 50-1000 ?g mL-1 with good correlation coefficient (0.992). The limits of assays detection was found to be 6.0 ?g mL-1 and quantitation limit was 20.0 ?g mL-1. The suggested method was applied to the determination of the drug in capsules. No interference could be observed from the additives in the capsules. The percentage recovery was found to be 100.43 1.24. Conclusion The developed method was successfully validated and applied to the determination of pregabalin in bulk and pharmaceutical formulations without any interference from common excipients. Hence, this method can be potentially useful for routine laboratory analysis of pregabalin. PMID:21982305

2011-01-01

90

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

NASA Astrophysics Data System (ADS)

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

Fayez, Yasmin Mohammed

2014-11-01

91

Optimized and validated spectrophotometric methods for the determination of enalapril maleate in commercial dosage forms.  

PubMed

Four simple, rapid and sensitive spectrophotometric methods have been proposed for the determination of enalapril maleate in pharmaceutical formulations. The first method is based on the reaction of carboxylic acid group of enalapril maleate with a mixture of potassium iodate (KIO(3)) and iodide (KI) to form yellow colored product in aqueous medium at 25 +/- 1 degrees C. The reaction is followed spectrophotometrically by measuring the absorbance at 352 nm. The second, third and fourth methods are based on the charge transfer complexation reaction of the drug with p-chloranilic acid (pCA) in 1, 4-dioxan-methanol medium, 2, 3-dichloro 5, 6-dicyano 1, 4-benzoquinone (DDQ) in acetonitrile-1,4 dioxane medium and iodine in acetonitrile-dichloromethane medium. Under optimized experimental conditions, Beer's law is obeyed in the concentration ranges of 2.5-50, 20-560, 5-75 and 10-200 microg mL(-1), respectively. All the methods have been applied to the determination of enalapril maleate in pharmaceutical dosage forms. Results of analysis are validated statistically. PMID:19609388

Rahman, Nafisur; Haque, Sk Manirul

2008-01-01

92

Optimized and Validated Spectrophotometric Methods for the Determination of Enalapril Maleate in Commercial Dosage Forms  

PubMed Central

Four simple, rapid and sensitive spectrophotometric methods have been proposed for the determination of enalapril maleate in pharmaceutical formulations. The first method is based on the reaction of carboxylic acid group of enalapril maleate with a mixture of potassium iodate (KIO3) and iodide (KI) to form yellow colored product in aqueous medium at 25 1C. The reaction is followed spectrophotometrically by measuring the absorbance at 352 nm. The second, third and fourth methods are based on the charge transfer complexation reaction of the drug with p-chloranilic acid (pCA) in 1, 4-dioxan-methanol medium, 2, 3-dichloro 5, 6-dicyano 1, 4-benzoquinone (DDQ) in acetonitrile-1,4 dioxane medium and iodine in acetonitrile-dichloromethane medium. Under optimized experimental conditions, Beers law is obeyed in the concentration ranges of 2.550, 20560, 575 and 10200 ?g mL?1, respectively. All the methods have been applied to the determination of enalapril maleate in pharmaceutical dosage forms. Results of analysis are validated statistically. PMID:19609388

Rahman, Nafisur; Haque, Sk Manirul

2008-01-01

93

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 orangered 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 (0.86, 0.84) for methods A and B, (1696, 1696 and 1672) for procedures 13 in method C. The limits of detection and quantitation were calculated, the precision of the methods were satisfactory; the values of relative standard deviations did not exceed 2%. The proposed methods were successfully applied to determine the drug in its pharmaceutical formulations without interference from the common excipients. The results obtained by the proposed methods were comparable with those obtained by the reference method. PMID:22219661

Abdellaziz, Lobna M.; Hosny, Mervat M.

2011-01-01

94

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

PubMed

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

Islam, K M S; Schweigert, F J

2015-04-01

95

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

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. PMID:23675288

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

2013-03-01

96

A new spectrophotometric method for quantification of potassium solubilized by bacterial cultures.  

PubMed

A new spectrophotometric method was developed for the quantification of potassium in the culture broth supernatant of K-solubilizing bacteria. The standard curve of potassium with the new method, which is based on the measurement of cobalt, showed a regression coefficient (R2) of 0.998. The quantification values of potassium obtained with flame photometric method and the newly developed method showed a significant correlation (r) of 0.978. The new method depends on the precipitation of sodium cobaltinitrite with solubilized potassium in liquid medium as potassium sodium cobaltinitrite, which develops bluish green colour by the addition of conc. HCl. The intensity of developed colour can be recorded at 623 nm. This method involves less number of steps, is easy and time saving, and can be used for the reliable estimation of available potassium in culture broth supernatant of K-solubilizing bacteria. PMID:24669669

Rajawat, Mahendra Vikram Singh; Singh, Surender; Saxena, Anil Kumar

2014-03-01

97

In Situ Spectrophotometric Determination of pH under Geologic CO2 Sequestration Conditions: Method Development and Application  

SciTech Connect

Injecting massive amounts of CO2 into deep geologic formations will cause a range of coupled thermal, hydrodynamic, mechanical, and chemical changes. A significant perturbation in water-saturated formations is the pH drop in the reservoir fluids due to CO2 dissolution. Knowing the pH under geological CO2 sequestration conditions is important for a better understanding of the short- and long-term risks associated with geological CO2 sequestration and will help in the design of sustainable sequestration projects. Most previous studies on CO2-rock-brine interactions have utilized thermodynamic modeling to estimate the pH. In this work, a spectrophotometric method was developed to determine the in-situ pH in CO2-H2O-NaCl systems in the presence and absence of reservoir rock by observing the spectra of a pH indicator, bromophenol blue, with a UV-visible spectrophotometer. Effects of temperature, pressure, and ionic strength on the pH measurement were evaluated. Measured pH values in CO2-H2O-NaCl systems were compared with several thermodynamic models. Results indicate that bromophenol blue can be used to accurately determine the pH of brine in contact with supercritical CO2 under geologic CO2 sequestration conditions.

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

2013-02-25

98

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

99

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. PMID:20376230

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

2009-01-01

100

Spectrophotometric method for simultaneous estimation of escitalopram oxalate and clonazepam in tablet dosage form.  

PubMed

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 mug/ml and 5-50 mug/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. PMID:20376230

Kakde, R B; Satone, D D

2009-11-01

101

Evaluation of spectrophotometric and fluorometric methods for alkaline phosphatase activity determination in ewe's milk.  

PubMed

The alkaline phosphatase (ALP) activity test has been used since 1935 to assess the effectiveness of pasteurization. Different analytical methods exist for detecting ALP in milk. Unfortunately, there is little information about ALP activity in ewe's milk. The aim of this study was to assess and compare the official European method (spectrophotometric method) and the Fluorophos method (fluorometric method) regarding their use in ewe's milk. Bulk ewe's milk samples were taken from a flock and from three different dairies. A portion of the original sample was pasteurized at 63 degrees C for 30 min in a circulating bath; another portion was heated to and kept at 95 degrees C for about 2 min, and 0.1% (vol/vol) of raw milk was added. The samples obtained were analyzed in duplicate using the spectrophotometric and fluorometric methods. The relation between ALP activity determined by the two methods was characterized by the following equation: Y = 1.34 + 0.0039X (where Y = ALP in microg of phenol per ml of milk and X = ALP in mU/liter; R2 = 91.5%). Precision parameters (repeatability [r], standard deviation of repeatability [s(r)], and relative standard deviation of repeatability [RSDr]) for both methods were calculated. The values of RSDr for the Fluorophos method were 4.30 for pasteurized milk and 2.96 for 0.1% raw milk, close to the value indicated by Rocco in whole cow's milk (RSDr = 4.4). The repeatability for the official method (r = 2.16) was close to that indicated for whole cow's milk (r = 2). PMID:10983802

Scintu, M F; Daga, E; Ledda, A

2000-09-01

102

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

PubMed

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

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

2007-09-01

103

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

PubMed

A simple multivariate calibration method for analysis of two types of hypotensive mixture is described. The mixtures are composed of chlorthalidone with atenolol or chlorthalidone with both amiloride hydrochloride and atenolol. The components of the mixtures result in substantial spectral overlap-between 87.5 and 91.0%. Resolution of the mixtures under investigation has been accomplished mainly by using CLS and PCR methods. The components in each mixture have been simultaneously determined in three commercial dosage forms with high accuracy and without interference from commonly encountered excipients and additives. Good recoveries were obtained with both synthetic mixtures and commercial tablets. The results obtained were compared with those from pharmacopeial methods and found to be in good agreement. The results obtained from CLS and PCR were also compared with those obtained from a 1D spectrophotometric method. PMID:15928945

Mohamed, Abd El-Maaboud I; Salem, Hesham

2005-06-01

104

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; Gonalves, Teresa; Borges, Olga

2013-06-01

105

Evaluation of spectrophotometric methods for screening of green rooibos (Aspalathus linearis) and green honeybush (Cyclopia genistoides) extracts for high levels of Bio-active compounds.  

PubMed

The potential of UV spectrophotometry and an aluminium chloride (AlCl(3)) colorimetric method to determine the dihydrochalcone (DHC) and mangiferin contents of green rooibos and honeybush (C. genistoides) extracts, respectively, was investigated. The DHC content of rooibos water extracts, determined using UV spectroscopy, correlated with the sum of the aspalathin and nothofagin contents as quantified using HPLC (r = 0.98). A correlation coefficient of 0.91 was obtained when correlating the mangiferin content of C. genistoides methanol extracts, determined by the AlCl(3) colorimetric method, with the results obtained by HPLC. Using the linear equations from the correlations it was possible to predict the DHC and mangiferin contents of extracts from the respective spectrophotometric measurements to a reasonable accuracy as an alternative to HPLC. The total polyphenol (TP) content of rooibos water extracts can also be determined using UV spectrophotometry and aspalathin as a standard (r = 0.99) as an alternative to the Folin-Ciocalteau method. The TP content of rooibos extracts correlated (r = 0.99) with its total antioxidant activity (TAA) as determined with the ABTS radical cation scavenging assay, but the TP content of C. genistoides water extracts is not a good indication of their TAA (r = 0.27). The aspalathin content of rooibos extracts correlated with their TAA (r = 0.96), but the mangiferin content of honeybush water extracts only gave a moderate correlation with their TAA (r = 0.75). PMID:17893845

Joubert, Elizabeth; Manley, Marena; Botha, Mariza

2008-01-01

106

Spectrophotometric determination of loperamide hydrochloride by acid-dye and charge-transfer complexation methods in the presence of its degradation products  

Microsoft Academic Search

Two simple, sensitive and accurate spectrophotometric methods for the determination of loperamide hydrochloride (lop. HCl) are described. The first method is based on the formation of ion-pair association complex (1:1) with bromothymol blue (BTB), bromophenol blue (BPB) and naphthol blue black B (NBB). The coloured products are extracted into chloroform, and measured spectrophotometrically at 414 (BTB), 415 (BPB) and 627

Z. A. El Sherif; A. O. Mohamed; M. I. Walash; F. M. Tarras

2000-01-01

107

Extractive spectrophotometric methods for determination of diltiazem HCl in pharmaceutical formulations using bromothymol blue, bromophenol blue and bromocresol green  

Microsoft Academic Search

Three simple and sensitive extractive spectrophotometric methods have been described for the assay of diltiazem hydrochloride either in pure form or in pharmaceutical formulations. The developed methods involve formation of coloured chloroform extractable ion-pair complexes of the drug with bromothymol blue (BTB), bromophenol blue (BPB) and bromocresol green (BCG) in acidic medium. The extracted complexes showed absorbance maxima at 415

Nafisur Rahman; Syed Najmul Hejaz-Azmi

2000-01-01

108

Simple, sensitive, selective and validated spectrophotometric methods for the estimation of a biomarker trigonelline from polyherbal gels  

NASA Astrophysics Data System (ADS)

Simple, accurate, reproducible, selective, sensitive and cost effective UV-spectrophotometric methods were developed and validated for the estimation of trigonelline in bulk and pharmaceutical formulations. Trigonelline was estimated at 265 nm in deionised water and at 264 nm in phosphate buffer (pH 4.5). Beer's law was obeyed in the concentration ranges of 1-20 ?g mL -1 ( r2 = 0.9999) in deionised water and 1-24 ?g mL -1 ( r2 = 0.9999) in the phosphate buffer medium. The apparent molar absorptivity and Sandell's sensitivity coefficient were found to be 4.04 10 3 L mol -1 cm -1 and 0.0422 ?g cm -2/0.001A in deionised water; and 3.05 10 3 L mol -1 cm -1 and 0.0567 ?g cm -2/0.001A in phosphate buffer media, respectively. These methods were tested and validated for various parameters according to ICH guidelines. The detection and quantitation limits were found to be 0.12 and 0.37 ?g mL -1 in deionised water and 0.13 and 0.40 ?g mL -1 in phosphate buffer medium, respectively. The proposed methods were successfully applied for the determination of trigonelline in pharmaceutical formulations (vaginal tablets and bioadhesive vaginal gels). The results demonstrated that the procedure is accurate, precise, specific and reproducible (percent relative standard deviation <2%), while being simple and less time consuming and hence can be suitably applied for the estimation of trigonelline in different dosage forms and dissolution studies.

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

2007-11-01

109

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

Microsoft Academic Search

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

Aldo Viarengo; Enrica Ponzano; Francesco Dondero; Rita Fabbri

1997-01-01

110

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

111

Spectrophotometric methods for simultaneous estimation of rabeprazole sodium and aceclofenac from the combined capsule dosage form  

PubMed Central

Introduction: The present work aimed to develop and validate spectrophotometric methods for simultaneous estimation of rabeprazole sodium and aceclofenac in a pure and capsule dosage form. Materials and Methods: Method 1 is based on solving a simultaneous equation. Absorbances of rabeprazole sodium and aceclofenac were measured at their respective absorbance maximas (?max) of 283 and 276 nm. Method 2 is the Q-analysis or absorption ratio method. Absorbances were measured at 256 nm (isosbestic point) and 276 nm (?max of aceclofenac). Methods are validated according to ICH guidelines. Results: A linearity range for rabeprazole sodium and aceclofenac is 1060 ?g/ml at respective selected wavelengths. The coefficient of correlation for rabeprazole at 283 nm and for aceclofenac at 276 nm is 0.9981 and 0.9997, respectively. A percentage estimation of rabeprazole sodium and aceclofenac from the capsule dosage form by method 1 is 100.22 and 99.96 and by method 2 is 99.99 and 100.05, respectively, with a standard deviation less than 2. Conclusion: The proposed methods are simple, rapid, and validated and can be used successfully for routine simultaneous estimation of rabeprazole sodium and aceclofenac in a pure and capsule dosage form. PMID:23781455

Sawant, Ramesh L.; Hadawale, Sanket D.; Dhikale, Ganesh K.; Bansode, Charusheela A.; Tajane, Pravin S.

2011-01-01

112

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 Qanalysis method (absorbance ratio), which involves the formation of Qabsorbance 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. PMID:20502567

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

2009-01-01

113

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

PubMed Central

Aim and Background: Three simple, accurate and sensitive spectrophotometric methods for the determination of finasteride in pure, dosage and biological forms, and in the presence of its oxidative degradates were developed. Materials and Methods: These methods are indirect, involve the addition of excess oxidant potassium permanganate for method A; cerric sulfate [Ce(SO4)2] for methods B; and N-bromosuccinimide (NBS) for method C of known concentration in acid medium to finasteride, and the determination of the unreacted oxidant by measurement of the decrease in absorbance of methylene blue for method A, chromotrope 2R for method B, and amaranth for method C at a suitable maximum wavelength, ?max: 663, 528, and 520 nm, for the three methods, respectively. The reaction conditions for each method were optimized. Results: Regression analysis of the Beer plots showed good correlation in the concentration ranges of 0.123.84 ?g mL1 for method A, and 0.123.28 ?g mL1 for method B and 0.14 3.56 ?g mL1 for method C. The apparent molar absorptivity, Sandell sensitivity, detection and quantification limits were evaluated. The stoichiometric ratio between the finasteride and the oxidant was estimated. The validity of the proposed methods was tested by analyzing dosage forms and biological samples containing finasteride with relative standard deviation ? 0.95. Conclusion: The proposed methods could successfully determine the studied drug with varying excess of its oxidative degradation products, with recovery between 99.0 and 101.4, 99.2 and 101.6, and 99.6 and 101.0% for methods A, B, and C, respectively. PMID:23781478

Amin, Alaa S.; Kassem, Mohammed A.

2012-01-01

114

Validated spectrophotometric methods for simultaneous determination of troxerutin and carbazochrome in dosage form.  

PubMed

Four simple, accurate, sensitive and precise spectrophotometric methods were developed and validated for simultaneous determination of Troxerutin (TXN) and Carbazochrome (CZM) in their bulk powders, laboratory prepared mixtures and pharmaceutical dosage forms. Method A is first derivative spectrophotometry (D(1)) where TXN and CZM were determined at 294 and 483.5nm, respectively. Method B is first derivative of ratio spectra (DD(1)) where the peak amplitude at 248 for TXN and 439nm for CZM were used for their determination. Method C is ratio subtraction (RS); in which TXN was determined at its ?max (352nm) in the presence of CZM which was determined by D(1) at 483.5nm. While, method D is mean centering of the ratio spectra (MCR) in which the mean centered values at 300nm and 340.0nm were used for the two drugs in a respective order. The two compounds were simultaneously determined in the concentration ranges of 5.00-50.00?gmL(-1) and 0.5-10.0?gmL(-1) for TXN and CZM, respectively. The methods were validated according to the ICH guidelines and the results were statistically compared to the manufacturer's method. PMID:25561299

Khattab, Fatma I; Ramadan, Nesrin K; Hegazy, Maha A; Al-Ghobashy, Medhat A; Ghoniem, Nermine S

2015-03-15

115

Development and validation of spectrophotometric, TLC and HPLC methods for the determination of lamotrigine in presence of its impurity.  

PubMed

Three reliable, rapid and selective methods have been developed and validated for the determination of lamotrigine in the presence of its impurity, 2,3-dichlorobenzoic acid. The first method is spectrophotometric method using p-chloranilic acid forming a colored product with lambda(max) 519+/-2 nm. All variables affecting the reaction have been investigated and the conditions were optimized. Beer's law was obeyed over a concentration range of 10-200 microg ml(-1) with mean accuracy 100.13+/-0.44%. The molar ratio of the formed ion-association complex is found to be 1 : 1 as deduced by Job's method. The conditional stability constant (K(f)), standard free energy (DeltaG), molar absorptivity(epsilon), and sensitivity index were evaluated. The second method is based on TLC separation of the cited drug (Rf=0.75+/-0.01) from its impurity (Rf=0.23+/-0.01) followed by densitometric measurement of the intact drug spots at 275 nm. The separation was carried on silica gel plates using ethyl acetate : methanol : ammonia 35% (17 : 2 : 1 v/v/v) as a mobile phase. The linearity range was 0.5-10 microg/spot with mean accuracy 99.99+/-1.33%. The third method is accurate and sensitive stability-indicating HPLC method based on separation of lamotrigine from its impurity on a reversed phase C(18) column, using a mobile phase of acetonitrile : methanol : 0.01 M potassium orthophosphate (pH 6.7+/-0.1) (30 : 20 : 50 v/v/v) at ambient temperature 25+/-5 degrees C and UV detection at 275 nm in an overall analysis time of about 6 min., based on peak area. The injection repeatability, intraday and interday repeatability were calculated. The procedure provided a linear response over the concentration range 1-12 microg ml(-1) with mean accuracy of 99.50+/-1.30%. The proposed methods were successfully applied for the determination of lamotrigine in bulk powder, in dosage form and in presence of its impurity. The results obtained were analyzed by ANOVA to assess that no significant difference between each of the three methods and the reported one. The validation was performed according to USP guidelines. PMID:17409544

Youssef, Nadia Fayek; Taha, Elham Anwer

2007-04-01

116

Kinetic spectrophotometric method for trace determination of thiocyanate based on its inhibitory effect  

NASA Astrophysics Data System (ADS)

A kinetic spectrophotometric method for the determination of thiocyanate, based on its inhibitory effect on silver(I) catalyzed substitution of cyanide ion, by phenylhydrazine in hexacyanoferrate(II) is described. Thiocyanate ions form strong complexes with silver(I) catalyst which is used as the basis for its determination at trace level. The progress of reaction was monitored, spectrophotometrically, at 488 nm ( ?max of [Fe(CN) 5PhNHNH 2] 3-, complex) under the optimum reaction conditions at: 2.5 10 -3 M [Fe(CN) 6] 4-, 1.0 10 -3 M [PhNHNH 2], 8.0 10 -7 M [Ag +], pH 2.8 0.02, ionic strength ( ?) 0.02 M (KNO 3) and temperature 30 0.1 C. A linear relationship obtained between absorbance (measured at 488 nm at different times) and inhibitor concentration, under specified conditions, has been used for the determination of [thiocyanate] in the range of 0.8-8.0 10 -8 M with a detection limit of 2 10 -9 M. The standard deviation and percentage error have been calculated and reported with each datum. A most plausible mechanistic scheme has been proposed for the reaction. The values of equilibrium constants for complex formation between catalyst-inhibitor ( KCI), catalyst-substrate ( Ks) and Michaelis-Menten constant ( Km) have been computed from the kinetic data. The influence of possible interference by major cations and anions on the determination of thiocyanate and their limits has been investigated.

Naik, Radhey M.; Kumar, Basant; Asthana, Abhas

2010-03-01

117

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

PubMed

Three simple, specific and accurate spectrophotometric methods manipulating ratio spectra were developed and validated for simultaneous determination of Rabeprazole sodium (RB) and Domperidone (DP) in their binary mixture without prior separation. Method A, is constant center spectrophotometric method (CC). Method B is a ratio difference spectrophotometric one (RD), while method C is a combined ratio isoabsorptive point-ratio difference method (RIRD). Linear correlations were obtained in range of 4-44?g/mL for both Rabeprazole sodium and Domperidone. The mean percentage recoveries of RB were 99.690.504 for method A, 99.830.483 for (B) and 100.310.499 for (C), respectively, and that of DP were 99.520.474 for method A, 100.120.505 for (B) and 100.160.498 for (C), respectively. Specificity was investigated by analysis of laboratory prepared mixtures containing the cited drugs and their combined tablet dosage form. The obtained results were statistically compared with those obtained by the reported methods, showing no significant difference with respect to accuracy and precision. The three methods were validated as per ICH guidelines and can be applied for routine analysis in quality control laboratories. PMID:24998682

Moustafa, H; Fayez, Y

2014-12-10

118

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

NASA Astrophysics Data System (ADS)

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

Moustafa, H.; Fayez, Y.

2014-12-01

119

Sensitive indirect spectrophotometric method for determination of h2-receptor antagonists in pharmaceutical formulations.  

PubMed

A simple, accurate and sensitive spectrophotometric method has been developed and validated for determination of H2-receptor antagonists: cimetidine, famotidine, nizatidine, and ranitidine hydrochloride. The method was based on the oxidation of these drugs with cerium (IV) in presence of perchloric acid and subsequent measurement of the excess Ce (IV) by its reaction with p-dimethylaminocinnamaldehyde to give a red colored product (?max at 464 nm). The decrease in the absorption intensity (?A) of the colored product, due to the presence of the drug was correlated with its concentration in the sample solution. Different variables affecting the reaction were carefully studied and optimized. Under the optimum conditions, linear relationships with good correlation coefficients (0.9985-0.9994) were found between ?A values and the concentrations of the drugs in a concentration range of 1-16 g ml(-1). The assay limits of detection and quantitation were 0.12-0.44 and 0.37-1.33 g ml(-1), respectively. The method was validated, in terms of accuracy, precision, ruggedness, and robustness; the results were satisfactory. The proposed method was successfully applied to the analysis of the investigated drugs in their pure and pharmaceutical dosage forms (recovery was 98.8-102.5 0.79-1.72%) without interference from the common excipients. The results obtained by the proposed method were comparable with those obtained by the official methods. PMID:23675034

Darwish, Ibrahim A; Hussein, Samiha A; Mahmoud, Ashraf M; Hassan, Ahmed I

2007-06-01

120

Spectrophotometric analysis of some guanidino drugs by acid-dye and charge-transfer complexation methods.  

PubMed

Two spectrophotometric methods are described for the determination of guanethidine sulphate (I), guanfacine hydrochloride (II), guanoclor sulphate (III), guanoxan sulphate (IV) and debrisoquine sulphate (V). The first method involves ion-pair formation of the selected compounds (I-V) with bromocresol purple at pH 3.8. The yellow ion pair is extracted with chloroform and the absorbance is measured at about 415 nm. The second method is based on the reaction of the basic guanidino compounds (I, III-V) with iodine in chloroform to give molecular charge-transfer complexes with maximum absorbance at 292 and 345 nm. Beer's law was obeyed for both methods and the relative standard deviations were found to be less than 2%. The apparent molar absorptivities were found to be 2.1 x 10(4) to 6.9 x 10(4) l mol-1 cm-1 using bromocresol purple and 0.7 x 10(4) to 2.4 x 10(4) l mol-1 cm-1 using iodine. The investigated drugs were assayed in tablets. The mean percentage recoveries were found to be 99.8-100.8% by the acid-dye method and around 100.4% by the charge-transfer complexation method. PMID:8257728

Wahbi, A A; Bedair, M M; Galal, S M; Gazy, A A

1993-08-01

121

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

PubMed

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

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

2006-10-01

122

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

123

Spectrophotometric Estimation of Raltegravir Potassium in Tablets  

PubMed Central

Ultra violet spectrophotometric estimation of the raltegravir potassium, an integrase inhibitor antiretroviral agent was estimated by Ultra violet absorption maxima method at ?max of 328 nm and UV area under curve method in the wave length range of 323-333 nm. The Beer's law obeyed in the concentration range of 3-55 ?g/ml and correlation coefficients were found to be more than 0.996 for both methods. The results of the analysis were 100.580.99 and 99.690.59 by absorption maxima and area under curve method respectively. Both the methods were validated as per ICH guidelines.

Kore, P. P.; Gamepatil, M. M.; Nimje, H. M.; Baheti, K. G.

2014-01-01

124

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

PubMed

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

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

2014-05-01

125

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 absorbanceconcentration 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. PMID:23675082

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

2008-01-01

126

Development of surfactant assisted spectrophotometric method for determination of selenium in waste water samples.  

PubMed

A new, simple and highly selective method for spectrophotometric determination of selenium in waste water samples is described. Selenium(IV) oxidizes I(-) ions into I(2) which subsequently reacts with excess of I(-) ion in the acidic media to give tri-iodide ions (I(3)(-)), and it further reacts with cetylpyridinium cation (CP(+)) to give a violet colored species. The value of molar absorptivity of the ion-associate species in terms of selenium is 1.80 x 10(4) L mol(-1)cm(-1) at lambda(max) 510 nm. The detection limit of the method is 10 ng mL(-1) Se. The calibration curve is linear over 50-1000 ng mL(-1) Se with slope, intercept and co-relation coefficient of 0.23, -4.0 x 10(-4) and +0.99, respectively. None of the tested diverse ions interfered in the present method. The method has been tested for the determination of selenium in waste water samples. PMID:18541371

Agrawal, Kavita; Patel, Khageshwar Singh; Shrivas, Kamlesh

2009-01-30

127

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

PubMed

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

Xia, Zhenzhen; Ni, Yongnian; Kokot, Serge

2013-12-15

128

Determination of vanadium in groundwater samples with an improved kinetic spectrophotometric method.  

PubMed

A kinetic catalytic method has been developed for the determination of vanadium based on its catalytic effect on the redox reaction of azorubin S and bromate in the presence of a sulphuric and nitric acid mixture. The reaction is monitored spectrophotometrically by measuring the decrease in absorbance of the reaction mixture at 515 nm. The fixed-time method was used for 0.5-5 min. Optimization of the reaction conditions regarding concentrations of acids, dye, oxidant, masking agent, etc. was investigated. The rate of decrease in absorbance of azorubin S was proportional to the concentration of vanadium in the range of 2.0-1.05 x 10(3) ng mL(-1). 3Sb/m was 0.0129 ng mL(-1) and 10 Sb/m was 0.0432 ng mL(-1). The catalytic method based on the oxidation reaction of azorubin S and bromate shows a good selectivity for vanadium over a wide variety of interference cations and anions. The proposed method was successfully applied to the determination of vanadium in groundwater samples and spiked-water samples. PMID:24701912

Ba?da, Esra

2014-01-01

129

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

130

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

PubMed

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

Al-Ghannam, S M

2006-01-23

131

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

PubMed

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

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

2014-09-01

132

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

133

A simple flow injection spectrophotometric determination method for iron(III) based on O -acetylsalicylhydroxamic acid complexation  

Microsoft Academic Search

A simple and rapid flow-injection spectrophotometric method for the determination of iron(III) and total iron is proposed.\\u000a The method is based on the reaction between iron(III) and O-acetylsalicylhydroxamic acid (AcSHA) in a 2 % methanol solution resulting in an intense violet complex with strong absorption\\u000a at 475 nm. Optimum conditions for the determination of iron(III) and the interfering ions were

Muberra Andac; Adem Asan; Ibrahim Isildak

2009-01-01

134

A differential kinetic spectrophotometric method for determination of three sulphanilamide artificial sweeteners with the aid of chemometrics  

Microsoft Academic Search

A simple and sensitive spectrophotometric method for the simultaneous determination of acesulfame-K, sodium cyclamate and saccharin sodium sweeteners in foodstuff samples has been researched and developed. This analytical method relies on the different kinetic rates of the analytes in their oxidative reaction with KMnO4 to produce the green manganate product in an alkaline solution. As the kinetic rates of acesulfame-K,

Yongnian Ni; Weiqiang Xiao; Serge Kokot

2009-01-01

135

Determination of manganese in some medicinal plants and their infusions by a catalytic spectrophotometric method.  

PubMed

The catalytic effect of manganese (II) on the oxidation of the azo dye 3-Methyl-6-(2-hydroxyethoxy)-2-[2-methoxy-4-N (N, N diethylamino) phenylazo] benzothiazolium methylsulphate, with potassium periodate in the presence of 1,10-phenanthroline in weakly acidic media was studied. The reaction was followed spectrophotometrically by measuring the decrease in the absorbance of the dye at 560 nm. Under the optimum conditions (4 x 10(-5) mol dm(-3) azo dye, 4 x 10(-4) mol dm(-3) potassium periodate, 1 x 10(-4) mol dm(-3) 1,10-phenanthroline, 0.1 mol dm(-3) buffer--pH 3.0, 70 degrees C, 8 min) manganese (II) in the range 0.1-5 ng cm(-3) could be determined by the fixed-time method with a detection limit of 0.035 ng cm(-3). The developed method is highly sensitive, selective, and simple. The method was applied successfully to the determination of total manganese in some medicinal plants and to analyse their infusions for trace amounts of total manganese and free manganese (II) ions without separation. PMID:15626243

Mutaftchiev, Konstantin

2004-11-01

136

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

PubMed Central

In this study, a new reaction system for quantitative determination of ascorbic acid was introduced. The developed method is based on inhibitory effect of ascorbic acid on the Orange G-bromate system. The change in absorbance was followed spectrophotometrically at 478 nm. The dependence of sensitivity on the reaction variables including reagents concentration, temperature and time was investigated. Under optimum experimental conditions, calibration curve was linear over the range 0.7 33.5 ?g mL-1 of ascorbic acid including two linear segments and the relative standard deviations (n = 6) for 5.0 and 20.0 ?g mL1 of ascorbic acid were 1.08 and 1.02%, respectively. The limit of detection was 0.21 ?g mL?1 of ascorbic acid. The effect of diverse species was also investigated. The developed method was successfully applied for the determination of ascorbic acid in pharmaceutical samples. The results were in a good agreement with those of reference method. PMID:25237333

Shishehbore, Masoud Reza; Aghamiri, Zahra

2014-01-01

137

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

PubMed

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

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

2006-01-01

138

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

139

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; Kepeki, S Evrim; Oztun, Aysel

2005-01-01

140

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

NASA Astrophysics Data System (ADS)

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

Aydo?mu?, Zeynep

2008-06-01

141

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

PubMed

Three sensitive, selective, accurate spectrophotometric and spectrofluorimetric methods have been developed for the determination of ropinirole hydrochloride in tablets. The first method was based on measuring the absorbance of drug solution in methanol at 250 nm. The Beer's law was obeyed in the concentration range 2.5-24 microg ml(-1). The second method was based on the charge transfer reaction of drug, as n-electron donor with 7,7,8,8-tetracyanoquinodimethane (TCNQ), as pi-acceptor in acetonitrile to give radical anions that are measured at 842 nm. The Beer's law was obeyed in the concentration range 0.6-8 microg ml(-1). The third method was based on derivatization reaction with 4-chloro-7-nitrobenzofurazan (NBD-Cl) in borate buffer of pH 8.5 followed by measuring the fluorescence intensity at 525 nm with excitation at 464 nm in chloroform. Beer's law was obeyed in the concentration range 0.01-1.3 microg ml(-1). The derivatization reaction product of drug with NBD-Cl was characterized by IR, 1H NMR and mass spectroscopy. The developed methods were validated. The following analytical parameters were investigated: the molar absorptivity (epsilon), limit of detection (LOD, microg ml(-1)) and limit of quantitation (LOQ, microg ml(-1)), precision, accuracy, recovery, and Sandell's sensitivity. Selectivity was validated by subjecting stock solution of ropinirole to acidic, basic, oxidative, and thermal degradation. No interference was observed from common excipients present in formulations. The proposed methods were successfully applied for determination of drug in tablets. The results of these proposed methods were compared with each other statistically. PMID:17719838

Aydo?mu?, Zeynep

2008-06-01

142

Estimation of phytotoxic aluminum in soil solution using three spectrophotometric methods  

SciTech Connect

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 virgatum L. cv. Cave-in-Rock) in limed and unlimed treatments of 10 acidic subsoil horizons. Across all 10 soils the amount of Al reacting with 8-hydroxyquinoline was generally the lowest, and that reacting with ferron the highest, although overlap among methods did occur. Manganese interference in several of the soil solutions limited the utility of the ferron method. The amounts of Al reacting with 8-hydroxyquinoline and aluminon were significantly related (P < 0.05) to root and shoot growth limitations exhibited by subterranean clover and switch-grass. Activities of Al/sup 3 +/ (a/sub Al/sup 3 +//) calculated from the GEOCHEM program using the Al reacting with 8-hydroxyquinoline and aluminon as the Al inputs were generally the best predictors of root and shoot growth.

Wright, R.J.; Wright, S.F.

1987-09-01

143

A sensitive spectrophotometric method for the determination of dithiocarbamate fungicide and its application in environmental samples.  

PubMed

A sensitive spectrophotometric method based on the evolution of CS(2) and colour development by leuco crystal violet is described for the determination of dithiocarbamate fungicides, e.g. thiram, ziram and zineb. Dithiocarbamate fungicides release CS(2) on acid hydrolysis. This CS(2) is absorbed in ethanolic sodium hydroxide and forms xanthate. The xanthate formed is subsequently treated with potassium iodate and N-chlorosuccinimide, during which free iodine is liberated. Crystal violet dye was formed through selective oxidation of leuco crystal violet by liberated iodine, which has an absorbance maxima at 595 nm. The colour systems obey Beer's law in the range of 0.02-0.20, 0.02-0.24 and 0.04-0.32 ppm for thiram, ziram and zineb respectively. The molar absorptivity of the colour system were found to be 9.6x10(5), 1.1x10(6) and 6.8x10(5)+/-100 l mol(-1) cm(-1) for thiram, ziram and zineb respectively. The method has been successfully applied to the determination of these dithiocarbamate fungicides in various environmental samples. PMID:18967100

Kesari, R; Gupta, V K

1998-04-01

144

A selective spectrophotometric method for determination of rosoxacin antibiotic using sodium nitroprusside as a chromogenic reagent.  

PubMed

A selective spectrophotometric method for the determination of rosoxacin (ROS), a 4-quinolone antimicrobial agent, has been developed and validated. The method was based on the reaction of ROS with alkaline sodium nitroprusside (SNP) reagent at room temperature forming a red colored chromogen measured at 455 nm. The conditions affecting the reaction (SNP concentration, pH, color-developing time, temperature, diluting solvent and chromogen stability time) were optimized. Under the optimum conditions, good linear relationship (r=0.9987) was obtained between the absorbance and the concentration of ROS in the range of 20-50 microg ml(-1). The assay limits of detection and quantitation were 2.5 and 8.4 microg ml(-1), respectively. The method was successfully applied to the analysis of bulk drug and laboratory-prepared tablets; the mean percentage recoveries were 100.1+/-0.33 and 101.24+/-1.28%, respectively. The results were compared favourably with those obtained by the reported method; no significant difference in the accuracy and precision as revealed by the accepted values of t- and F-tests, respectively. The robustness and ruggedness of the method was checked and satisfactory results were obtained. The proposed method was found to be highly selective for ROS among the fluoroquinolone antibiotics. The reaction mechanism was proposed and it proceeded in two steps; the formation of nitroferrocyanide by the action of sodium hydroxide alkalinity on SNP and the subsequent formation of the colored nitrosyl-ROS derivative by the attack at position 6 of ROS. PMID:17804284

Askal, Hassan F; Refaat, Ibrahim H; Darwish, Ibrahim A; Marzouq, Mostafa A

2008-04-01

145

a New Simultaneous Spectrophotometric Method for Determination of Iron(ii) and Iron(iii) in Natural Waters  

Microsoft Academic Search

A new analytical method employing di-2-pyridyl ketone salicyloylhydrazone (DPKSH) as a colorimetric chelating agent for simultaneous spectrophotometric determination of iron(II) and iron(III) in natural waters has been developed. Both of the complex ions show an absorbance maximum at 375 nm, with 4.21 10 and 1.26 10 l mol cm as the molar absorptivities, respectively, for Fe(II)

Madalena C. da Cunha Areias; Lcia Helena S. vila-Terra; Ivanise Gaubeur; Maria Encarnacin V. Surez-Iha

2001-01-01

146

[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; Gom?ka, Ewa; Zyss, Tomasz; Zieba, Andrzej; Florek, Ewa; Piekoszewski, Wojciech

2012-01-01

147

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

2010-01-01

148

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

PubMed Central

The present study describes a simple and highly selective method for separation, preconcentration and spectrophotometric determination of extremely low concentrations of lead. It is based on flotation of a complex of Pb2+ ions and Alizarin yellow between aqueous and n-hexane interface at pH = 6. The proposed procedure is also applied for determination of lead in both tap water and prepared sea water samples. Beers Law was obeyed over the concentration range of 3.86 108 To 8.20 107 molL?1 (8170 ngmL?1) with an apparent molar absorptivity of 1.33 106 molL?1 cm?1 for a 100 mL aliquot of the water sample. The detection limit (n = 10) was 8.7 109 molL?1 (1.0 ngmL?1) and the Relative standard deviation (R.S.D), (n = 10) for 7.2 107 molL?1 (150 ngmL?1) of Pb (II) was 4.36%. A notable advantage of the method is that the determination of Pb (II) is free from the interference of almost all cations and ions found in the environment and waste water samples. The determination of Pb (II) in tap and synthetic seawater samples was also carried out by the present method. The results were satisfactorily comparable so that the applicability of the proposed method was confirmed to the real samples.

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

2011-01-01

149

A novel spectrophotometric method for batch and flow injection determination of cyanide in electroplating wastewater.  

PubMed

A sensitive and highly selective spectrophotometric method is described for the determination of cyanide. It is based on a reaction of cyanide with aquacyanocobyrinic acid heptamethyl ester (ACCbs) reagent (orange color) at pH 9.5 to give dicyanocobester (DCCbs) (violet color). The increase of the absorption bands of the reaction product at 368 and 580nm and the decrease of the reagent band at 353nm are linearly proportional to the cyanide concentration. The method is used in static mode for determining cyanide over the concentration range 0.04-1.20mugml(-1) with a detection limit of 0.02mugml(-1) and for hydrodynamic analysis of 0.4-5.2mugml(-1) cyanide. Application for batch and flow injection monitoring of cyanide in electroplating wastewater samples gives results agree within+/-1.2% with those obtained by the standard potentiometry using the cyanide ion selective electrode. The method is practically free from interferences by PO(4)(3-), NO(3)(-), NO(2)(-), SO(4)(2-), F(-), Cl(-), Br(-), I(-), S(2-) and SCN(-) ions and gives results with average recoveries of 97.6-99.2%. Advantages offered by using ACCbs as a chromogen for cyanide assay are: (i) high selectivity and sensitivity of the coordination site of the reagent towards cyanide ion; (ii) fast reaction, since legation takes place at the axial position of the reagent; (iii) good solubility and stability of the reagent in aqueous solutions over a wide pH range; (iv) high stability of the reagent (ACCbs) and the colored complex product (DCCbs) and (v) possible absorbance measurements at three different wavelengths. PMID:19071417

Hassan, Saad S M; Hamza, Mohamed S A; Kelany, Ali E

2007-02-28

150

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

151

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 mol/L by UV and <0.4 mol/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). PMID:19782219

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

2009-01-01

152

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

PubMed

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

Finete, Virgnia de Lourdes Mendes; Gouva, Marcos Martins; Marques, Flvia Ferreira de Carvalho; Netto, Annibal Duarte Pereira

2013-12-15

153

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

PubMed

New, accurate, sensitive and reliable kinetic spectrophotometric method for the assay of moxifloxacin hydrochloride (MOXF) in pure form and pharmaceutical formulations has been developed. The method involves the oxidative coupling reaction of MOXF with 3-methyl-2-benzothiazolinone hydrazone hydrochloride monohydrate (MBTH) in the presence of Ce(IV) in an acidic medium to form colored product with lambda max at 623 and 660nm. The reaction is followed spectrophotometrically by measuring the increase in absorbance at 623nm as a function of time. The initial rate and fixed time methods were adopted for constructing the calibration curves. The linearity range was found to be 1.89-40.0?gmL(-1) for initial rate and fixed time methods. The limit of detection for initial rate and fixed time methods is 0.644 and 0.043?gmL(-1), respectively. Molar absorptivity for the method was found to be 0.8910(4)Lmol(-1)cm(-1). Statistical treatment of the experimental results indicates that the methods are precise and accurate. The proposed method has been applied successfully for the estimation of moxifloxacin hydrochloride in tablet dosage form with no interference from the excipients. The results are compared with the official method. PMID:25596545

Ashour, Safwan; Bayram, Roula

2015-04-01

154

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

PubMed Central

Simple, accurate and precise spectroflourometric and spectrophotometric methods have been developed and validated for the determination of sitagliptin phosphate monohydrate (STG) and metformin HCL (MET). Zero order, first derivative, ratio derivative spectrophotometric methods and flourometric methods have been developed. The zero order spectrophotometric method was used for the determination of STG in the range of 50-300 ?g mL-1. The first derivative spectrophotometric method was used for the determination of MET in the range of 212 ?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 212 ?g mL-1. The flourometric method was used for the determination of STG in the range of 0.25-110 ?g mL-1. The proposed methods used to determine each drug in binary mixture with metformin and ternary mixture with metformin and sitagliptin alkaline degradation product that is obtained after alkaline hydrolysis of sitagliptin. The results were statistically compared using one-way analysis of variance (ANOVA). The methods developed were satisfactorily applied to the analysis of the pharmaceutical formulations and proved to be specific and accurate for the quality control of the cited drugs in pharmaceutical dosage forms. PMID:23675222

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

2011-01-01

155

Spectrophotometric and Spectrofluorimetric Methods for the Determination of Dothiepin Hydrochloride in its Pure and Dosage Forms using Eosin  

PubMed Central

Spectrophotometric and spectrofluorimetric methods were developed for the determination of dothiepin hydrochloride (DOP) in different dosage forms. The spectrophotometric method (Method I) is based on formation of a binary complex with eosin at 540 nm in acetate buffer of pH3.7. The absorbance-concentration plot is rectilinear over the range 110 ?g/mL with LOD of 0.18 ?g/mL and LOQ of 0.54 ?g/mL. The spectroflurimetric method (Method II) is based on the quantitative quenching effect of Dothiepin on the native fluorescence of eosin at the same pH. The quenching of the fluorescence of eosin was measured at 543 nm after excitation at 304 nm. The fluorescence-concentration plot is rectilinear over the range 0.38 ?g/ mL with LOD of 0.11 ?g/mL and LOQ of 0.34 ?g/mL. The proposed methods were successfully applied to the analysis of commercial tablets and capsules containing the drug. Statistical comparison of the results with those of the reference method revealed good agreement and proved that there were no significant differences in the accuracy and precision between the two methods respectively. PMID:23675210

Walash, M. I.; Belal, F.; El-Enany, N.; Elmansi, H.

2010-01-01

156

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 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 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

157

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

PubMed

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

Misiuk, Wies?awa

2005-01-01

158

A Spectrophotometric Method for Determining the Oxidative Deamination of Methylamine by the Amine Oxidases  

Microsoft Academic Search

Previously published studies on the oxidative deamination of methylamine by the amine oxidases have determined the formation of radioactively labeled formaldehyde from [14C]methylamine. The present work describes a coupled spectrophotometric assay, using formaldehyde dehydrogenase, for the continuous determination of the oxidative deamination of methylamine by semicarbazide-sensitive amine oxidase (SSAO) and its potential use for determining methylamine concentrations in plasma. In

Jos M. Lizcano; Mercedes Unzeta; Keith F. Tipton

2000-01-01

159

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

160

Stability-indicating spectrophotometric and spectrofluorimetric methods for determination of alfuzosin hydrochloride in the presence of its degradation products.  

PubMed

Validated stability-indicating spectrophotometric and spectrofluorimetric assays (SIAMs) were developed for the determination of alfuzosin hydrochloride (ALF) in the presence of its oxidative, acid, and alkaline degradation products. Three spectrophotometric methods were suggested for the determination of ALF in the presence of its oxidative degradation product; these included the use of zero order (0D), first order (1D), and third order (3D) spectra. The absorbance was measured at 330.8 nm for (0D) method, while the amplitude of first derivative (1D) method and that of third derivative (3D) method were measured at 354.0 and 241.2 nm, respectively. The linearity ranges were 1.0-40.0 microg/ml for (0D) and (1D) methods, and 1.0-10.0 microg/ml for (3D) method. Two spectrofluorimetric methods were developed, one for determination of ALF in the presence of its oxidative degradation product and the other for its determination in the presence of its acid or alkaline degradation products. The first method was based on measuring the native fluorescence of ALF in deionized water using lamda(excitation) 325.0 nm and lamda(emission) 390.0 nm. The linearity range was 50.0-750.0 ng/ml. This method was also used to determine ALF in human plasma with the aid of a suggested solid phase extraction method. The second method was used for determination of ALF via its acid degradation product. The method was based on the reaction of fluorescamine with the primary aliphatic amine group produced on the degradation product moiety. The reaction product was determined spectrofluorimetrically using lamda(excitation) 380.0 nm and lamda(emission) 465.0 nm. The linearity range was 100.0-900.0 ng/ml. All methods were validated according to the International Conference on Harmonization (ICH) guidelines, and applied to bulk powder and pharmaceutical formulations. PMID:18065098

Fayed, A S; Shehata, M A; Hassan, N Y; Weshahy, S A

2007-11-01

161

Simple, sensitive and selective spectrophotometric methods for the determination of atenolol in pharmaceuticals through charge transfer complex formation reaction.  

PubMed

Three rapid, selective and sensitive spectrophotometric methods have been proposed for the quantitative determination of atenolol (ATN) in pure form as well as in its pharmaceutical formulation. The methods are based on charge transfer complexation reaction of ATN as n-electron donor with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), 2,4-dinitrophenol (DNP) and 2,4,6-trinitrophenol (picric acid; PA) as pi-acceptors to give highly colored radical anion species. The colored products were quantified spectrophotometrically at 590 nm with DDQ (method A) and at 420 nm with both DNP (method B) and PA (method C). Under the optimized experimental conditions, Beer's law is obeyed over the concentration ranges of 3-48, 2-24 and 1.5-18 ?g/mL ATN for method A, method B and method C, respectively. The molar absorptivity, Sandell sensitivity, limits of detection and quantification are also reported. The effects of reaction medium, reaction time and reagent concentration on the sensitivity and stability of the complexes formed have been examined. The proposed methods were successfully applied to the determination of ATN in pure form and commercial tablets with good accuracy and precision. Statistical comparison of the results was performed using Student's t-test and F-ratio at 95% confidence level and the results showed no significant difference between the reference and proposed methods with regard to accuracy and precision. Further, the accuracy and reliability of the methods were confirmed by recovery studies via standard addition technique. PMID:22568035

Prashanth, Kudige Nagaraju; Basavaiah, Kanakapura

2012-01-01

162

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

163

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

PubMed

Three sensitive, selective, and precise stability indicating methods for the determination of the X-ray contrast agent, diatrizoate sodium (DTA), in the presence of its acidic degradation product (highly cytotoxic 3,5 diamino metabolite) and in pharmaceutical formulation were developed and validated. The first method is a first derivative (D1) spectrophotometric one, which allows the determination of DTA in the presence of its degradate at 231.2nm (corresponding to zero crossing of the degradate) over a concentration range of 2-24?g/mL with mean percentage recovery 99.950.97%. The second method is the first derivative of the ratio spectra (DD1) by measuring the peak amplitude at 227nm over the same concentration range as D1 spectrophotometric method, with mean percentage recovery 99.991.15%. The third method is a TLC-densitometric one, where DTA was separated from its degradate on silica gel plates using chloroform:methanol:ammonium hydroxide (20:10:2 by volume) as a developing system. This method depends on quantitative densitometric evaluation of thin layer chromatogram of DTA at 238nm over a concentration range of 4-20?g/spot, with mean percentage recovery 99.880.89%. The selectivity of the proposed methods was tested using laboratory-prepared mixtures. The proposed methods have been successfully applied to the analysis of DTA in pharmaceutical dosage forms without interference from other dosage form additives. The results were statistically compared with the official US pharmacopeial method. No significant difference for either accuracy or precision was observed. PMID:25456658

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

2015-02-01

164

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

165

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

166

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

2013-05-15

167

Development and validation of chemometrics-assisted spectrophotometric and liquid chromatographic methods for the simultaneous determination of two multicomponent mixtures containing bronchodilator drugs  

Microsoft Academic Search

Three methods are developed for the determination of two multicomponent mixtures containing guaiphenesine (GU) with salbutamol sulfate (SL), methylparaben (MP) and propylparaben (PP) [mixture 1]; and acephylline piperazine (AC) with bromhexine hydrochloride (BX), methylparaben (MP) and propylparaben (PP) [mixture 2]. The resolution of the two multicomponent mixtures has been accomplished by using numerical spectrophotometric methods such as partial least squares

Alaa El-Gindy; Samy Emara; Heba Shaaban

2007-01-01

168

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

Microsoft Academic Search

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

Nafisur Rahman; Nadeem Ahmad Khan; Syed Najmul Hejaz Azmi

2004-01-01

169

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. PMID:22305461

2012-01-01

170

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

NASA Astrophysics Data System (ADS)

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

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

171

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

PubMed

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

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

2014-05-21

172

A spectrophotometric method for determining the oxidative deamination of methylamine by the amine oxidases.  

PubMed

Previously published studies on the oxidative deamination of methylamine by the amine oxidases have determined the formation of radioactively labeled formaldehyde from [(14)C]methylamine. The present work describes a coupled spectrophotometric assay, using formaldehyde dehydrogenase, for the continuous determination of the oxidative deamination of methylamine by semicarbazide-sensitive amine oxidase (SSAO) and its potential use for determining methylamine concentrations in plasma. In this assay, the formaldehyde produced by methylamine deamination is further oxidized to formate, with the reduction of NAD(+), by formaldehyde dehydrogenase. The NADH generated is monitored continuously at 340 nm. Interference from the presence of a rotenone-insensitive NADH oxidase activity in crude tissue homogenates and microsomal fractions can be minimized by pretreating samples with Triton X-100 or substituting NAD(+) by APAD(+) in the coupled assay. This relatively inexpensive and reproducible assay procedure avoids the use of radioactively labeled material. PMID:11038276

Lizcano, J M; Unzeta, M; Tipton, K F

2000-11-01

173

Spectrophotometric measurement of calcium carbonate saturation states in seawater.  

PubMed

Measurements of ocean pH and carbonate ion concentrations in the North Pacific and Arctic Oceans were used to determine calcium carbonate saturation states (?(CaCO(3))) from spectrophotometric methods alone. Total carbonate ion concentrations, [CO(3)(2-)](T), were for the first time at sea directly measured using Pb(II) UV absorbance spectra. The basis of the method is given by the following: [formula see text] where (CO(3))?(1) is the PbCO(3)(0) formation constant, e(i) are molar absorptivity ratios, and R = (250)A/(234)A (ratio of absorbances measured at 250 and 234 nm). On the basis of shipboard and laboratory Pb(II) data and complementary carbon-system measurements, the experimental parameters were determined to be (25 C) the following: [formula see text]. The resulting mean difference between the shipboard spectrophotometric and conventional determinations of [CO(3)(2-)](T) was 2.03 ?mol kg(-1). The shipboard analytical precision of the Pb(II) method was ?1.71 ?mol kg(-1) (2.28%). Spectrophotometric [CO(3)(2-)](T) and pH(T) were then combined to calculate ?(CaCO(3)). For the case of aragonite, 95% of the spectrophotometric aragonite saturation states (?(Aspec)) were within 0.06 of the conventionally calculated values (?(Acalc)) when 0.5 ? ?(A) ? 2.0. When ?(A) > 2.0, 95% of the ?(Aspec) values were within 0.18 of ?(Acalc). Our shipboard experience indicates that spectrophotometric determinations of [CO(3)(2-)](T) and ?(CaCO(3)) are straightforward, fast, and precise. The method yields high-quality measurements of two important, rapidly changing aspects of ocean chemistry and offers capabilities suitable for long-term automated in situ monitoring. PMID:23198742

Easley, Regina A; Patsavas, Mark C; Byrne, Robert H; Liu, Xuewu; Feely, Richard A; Mathis, Jeremy T

2013-02-01

174

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

PubMed

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

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

2008-01-01

175

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

PubMed

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

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

2011-12-01

176

Simple Spectrophotometric Method for Determination of Paroxetine in Tablets Using 1,2-Naphthoquinone-4-Sulphonate as a Chromogenic Reagent  

PubMed Central

Simple and rapid spectrophotometric method has been developed and validated for the determination of paroxetine (PRX) in tablets. The proposed method was based on nucleophilic substitution reaction of PRX with 1,2-naphthoquinone-4-sulphonate (NQS) in an alkaline medium to form an orange-colored product of maximum absorption peak (?max) at 488 nm. The stoichiometry and kinetics of the reaction were studied, and the reaction mechanism was postulated. Under the optimized reaction conditions, Beer's law correlating the absorbance (A) with PRX concentration (C) was obeyed in the range of 18 ?g mL?1. The regression equation for the calibration data was: A = 0.0031 + 0.1609 C, with good correlation coefficients (0.9992). The molar absorptivity (?) was 5.9 105 L mol?1 1 cm?1. The limits of detection and quantitation were 0.3 and 0.8 ?g mL?1, respectively. The precision of the method was satisfactory; the values of relative standard deviations did not exceed 2%. The proposed method was successfully applied to the determination of PRX in its pharmaceutical tablets with good accuracy and precisions; the label claim percentage was 97.17 1.06 %. The results obtained by the proposed method were comparable with those obtained by the official method. PMID:20107559

Darwish, Ibrahim A.; Abdine, Heba H.; Amer, Sawsan M.; Al-Rayes, Lama I.

2009-01-01

177

Simultaneous Assay of Atenolol and Nifedipine by UV Derivative Spectrophotometry and Gaschromatography  

Microsoft Academic Search

A rapid, simple, and accurate UV derivative method for the simultaneous determination of atenolol and nifedipine in dosage forms was developed. A new gaschromatographic procedure was also defined to convalide the spectrophotometric procedure as an alternative method. Statistical analysis of the results on data from laboratory solutions confirms a good accuracy and precision of both the methods.

M. Veronico; G. Ragno; C. Vetuschi

1995-01-01

178

A spectrophotometric method to measure enzymatic activity in reactions that generate inorganic pyrophosphate.  

PubMed

This paper describes a spectrophotometric assay that can measure the inorganic pyrophosphate produced from various enzymatic reactions. This is a coupled assay in which the addition of inorganic pyrophosphatase initially cleaves the pyrophosphate into two molecules of phosphate. The phosphate is then detected by the conversion of 2-amino-6-mercapto-7-methylpurine ribonucleoside to 2-amino-6-mercapto-7-methylpurine by purine nucleoside phosphorylase [M.R. Webb (1992) Proc. Natl. Acad. Sci. USA 89, 4884-4887]. The reaction is monitored by measuring the increase in absorbance at 360 nm. The generation of two molecules of phosphate from each molecule of pyrophosphate increases the sensitivity of the assay, which has a linear range from about 1 to 75 nmol pyrophosphate in a 1-ml reaction volume. To demonstrate the general usefulness of this assay, we show that the inorganic pyrophosphate generated by reactions involving acetyl-CoA synthetase and luciferase can be readily detected and that continuous as well as end-point assays can be performed. PMID:8954523

Upson, R H; Haugland, R P; Malekzadeh, M N; Haugland, R P

1996-12-01

179

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

PubMed

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

Bennedsen, Lars Rnn; Sgaard, Erik Gydesen; Muff, Jens

2014-11-01

180

Development of sensitive spectrofluorimetric and spectrophotometric methods for the determination of duloxetine in capsule and spiked human plasma.  

PubMed

A new, sensitive and selective spectrofluorimetric method has been developed for the determination of duloxetine (DLX) in capsule and spiked human plasma. DLX, as a secondary amine compound, reacts with 7-chloro-4-nitrobenzofurazon (NBD-Cl), a highly sensitive fluorogenic and chromogenic reagent used in many investigations. The method is based on the reaction between the drug and NBD-Cl in borate buffer at pH?8.5 to yield a highly fluorescent derivative that is measured at 523?nm after excitation at 478?nm. The fluorescence intensity was directly proportional to the concentration over the range 50-250?ng/mL. The reaction product was also measured spectrophotometrically. The relation between the absorbance at 478?nm and the concentration is rectilinear over the range 1.0-12.0?g/mL. The methods were successfully applied for the determination of this drug in pharmaceutical dosage form. The spectrofluorimetric method was also successfully applied to the determination of duloxetine in spiked human plasma. The suggested procedures could be used for the determination of DLX in pure form, capsules and human plasma being sensitive, simple and selective. Copyright 2014 John Wiley & Sons, Ltd. PMID:24619645

Sagirli, Olcay; Toker, S?d?ka Erturk; Onal, Arma?an

2014-12-01

181

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

182

A kinetic spectrophotometric method for simultaneous determination of phenol and its three derivatives with the aid of artificial neural network.  

PubMed

A novel kinetic spectrophotometric method was developed for determination of pyrocatechol, resorcin, hydroquinone and phenol based on their inhibitory effect on the oxidation of Rhodamine B (RhB) in acid medium at pH=3.0. A linear relationship was observed between the inhibitory effect and the concentrations of the compounds. The absorbance associated with the kinetic reactions was monitored at the maximum wavelength of 557nm. The effects of different parameters such as pH, concentration of RhB and KBrO(3), and temperature of the reaction were investigated and optimum conditions were established. The linear ranges were 0.22-3.30, 0.108-0.828, 0.36-3.96 and 1.52-19.76?g mL(-1) for pyrocatechol, resorcin, hydroquinone and phenol, respectively, and their corresponding detection limits were 0.15, 0.044, 0.16 and 0.60?g mL(-1). The measured data were processed by several chemometrics methods, such as principal component regression (PCR), partial least squares (PLS) and artificial neural network (ANN), and a set of synthetic mixtures of these compounds was used to verify the established models. It was found that the prediction ability of PLS, PCR and RBF-ANN was similar, however, the RBF-ANN model did perform somewhat better than the other methods. The proposed method was also applied satisfactorily for the simultaneous determination of pyrocatechol, resorcin, hydroquinone and phenol in real water samples. PMID:21719195

Ni, Yongnian; Xia, Zhenzhen; Kokot, Serge

2011-08-30

183

Extractive spectrophotometric method for determination of metribuzin herbicide and application of factorial design in optimization of various factors.  

PubMed

A simple extractive spectrophotometric method has been described for the determination of metribuzin herbicide. Metribuzin was reacted with copper and a stable complex in the presence of ammonia (0.2M) at pH 10.5 was formed. The resulting yellow coloured complex was extracted in chloroform and showed absorption maxima at 340 nm. Beer's law was obeyed in the range of 0.8-25 microg mL(-1) with molar absorptivity of 5.67 x 10(3)L mol(-1)cm(-1). The composition of the complex was studied by Job's method of continuous variation and the results indicated that the mole ratio of metribuzin:Cu(2+) is 2:1. The optimum reaction conditions for complexation and other analytical parameters were evaluated. A two-level factorial design was also used to determine the effect of different parameters and their interaction on metribuzin:Cu(2+) complex formed. The method was successfully applied for the determination of metribuzin in commercial formulations and real samples. PMID:18930595

Shah, Jasmin; Jan, M Rasul; Ara, Behisht; Mohammad, Mian

2009-05-30

184

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

PubMed

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

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

2013-01-01

185

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

186

Development and application of a shipboard method for spectrophotometric determination of trace dissolved manganese in estuarine and coastal waters  

NASA Astrophysics Data System (ADS)

A shipboard method for the determination of trace dissolved manganese in estuarine and coastal waters was developed using a technique of reverse flow injection analysis, which adopted a 1-m liquid waveguide capillary cell and spectrophotometric detection of manganese derivation with 1-(2-pyridylazo)-2-naphthol (PAN). The design of dual-sample-carrier speeded up the sample throughput and eliminated the Schlieren effect. The salinity of estuarine and coastal waters caused a huge increase in the blank absorption value at the maximum absorption wavelength; therefore, a less sensitive detection wavelength was selected to achieve a low blank value while the method sensitivity was not significantly decreased. Method parameters were optimized. The salinity effect from estuarine and coastal waters was carefully investigated, and interference from iron was evaluated. The proposed method had high sensitivity with a detection limit of 3.0 nmol L-1 and a wide linear range of 10-1500 nmol L-1 for dissolved manganese in seawater (S=35). The analytical results of five water samples with different salinities obtained using the proposed method showed good agreement with those using a reference ICP-MS method. The sample throughput of the proposed method was 120 h-1, which was capable of obtaining high spatial and temporal resolution data in shipboard analysis. The proposed method had the advantages of convenient application in estuarine and coastal waters with different salinities, low detection limit, as well as high sample throughput. The proposed method was successfully applied to a 24 h on-line analysis and a shipboard underway analysis of dissolved manganese in the Jiulongjiang Estuary.

Feng, Sichao; Huang, Yongming; Yuan, Dongxing; Zhu, Yong; Zhou, Tingjin

2015-01-01

187

Spectrophotometric determination of ascorbic acid by the modified CUPRAC method with extractive separation of flavonoids-La(III) complexes.  

PubMed

The proposed method for ascorbic acid: AA (Vitamin C) determination is based on the oxidation of AA to dehydroascorbic acid with the CUPRAC reagent of total antioxidant capacity assay, i.e., Cu(II)-neocuproine (Nc), in ammonium acetate-containing medium at pH 7, where the absorbance of the formed bis(Nc)-copper(I) chelate is measured at 450 nm. The flavonoids (essentially flavones and flavonols) normally interfering with the CUPRAC procedure were separated with preliminary extraction as their La(III) chelates into ethylacetate (EtAc). The Cu(I)-Nc chelate responsible for color development was formed immediately with AA oxidation. Beer's law was obeyed between 8.0 x 10(-6) and 8.0 x 10(-5) M concentration range, with the equation of the linear calibration curve: A(450 nm)=1.60 x 10(4)C (mol dm(-3))-0.0596. The relative standard deviation (R.S.D.) in the analysis of N=45 synthetic mixtures containing 1.25 x 10(-2) mM AA with flavonoids was 5.3%. The Cu(II)-Nc reagent is a lower redox-potential and therefore more selective oxidant than the Fe(III)-1,10-phenanthroline reagent conventionally used for the same assay. This feature makes the proposed method superior for real samples such as fruit juices containing weak reductants such as citrate, oxalate and tartarate that may otherwise produce positive errors in the Fe(III)-phen method when equilibrium is achieved. The developed method was applied to some commercial fruit juices and pharmaceutical preparations containing Vitamin C+bioflavonoids. The findings of the developed method for fruit juices and pharmaceuticals were statistically alike with those of HPLC. The proposed spectrophotometric method was practical, low-cost, rapid, and could reliably assay AA in the presence of flavonoids without enzymatic procedures open to interferences by enzyme inhibitors. PMID:17386797

Ozyrek, Mustafa; Gl, Kubilay; Bekta?o?lu, Burcu; Apak, Re?at

2007-04-01

188

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

189

Spectrophotometric probe  

SciTech Connect

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

190

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

Microsoft Academic Search

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

Theiaa N. Al-Sabha; Andrei A. Bunaciu; Hassan Y. Aboul-Enein

2011-01-01

191

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

192

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

2007-07-01

193

Spectrophotometric method of determining the transmission of solar energy in salt gradient solar ponds. Final Report  

Microsoft Academic Search

In order to predict the thermal efficiency of a solar pond it is necessary to know total average solar energy reaching the storage layer. One method for determining this energy for water containing dissolved colored species is based upon spectral transmission measurements using a laboratory spectrophotometer. This method is examined and some of the theoretical ground work needed to discuss

Giulianelli

1984-01-01

194

The spectrophotometric method of determining the transmission of solar energy in salt gradient solar ponds  

Microsoft Academic Search

In order to predict the thermal efficiency of a solar pond it is necessary to know total average solar energy reaching the storage layer. One method for determining this energy for water containing dissolved colored species is based upon spectral transmission measurements using a laboratory spectrophotometer. This method is examined and some of the theoretical ground work needed to discuss

J. Giulianelli

1984-01-01

195

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

PubMed

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

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

1997-07-01

196

New Spectrophotometric Method for Simultaneous determination of Metoprolol Tartarate and Hydrochlorthiazide in Tablets  

PubMed Central

The present work describes a two-wavelength method for simultaneous determination of metoprolol and hydrochlorthiazide in fixed dose combination tablet. The wavelengths selected for method were 257.8 nm, 282.9 nm and 315.0 nm. The absorbance difference at first two wavelengths was used for determination of metoprolol and the latter was used for determination of hydrochlorthiazide. The recovery value for the drugs from the tablet matrix was found to be 100.55% (metoprolol) and 99.97% (comparison with standard) and 98.09% (E1%, 1cm) for hydrochlorthiazide. The method has an advantage that hydrochlorthiazide can be estimated in combination, as there is no interference of metoprolol at 315.0 nm. The method was evaluated statistically for its accuracy and precision. PMID:20046783

Gupta, K. R.; Tajne, M. R.; Wadodkar, S. G.

2008-01-01

197

Ultraviolet spectrophotometric method for determination of cholinesterase activity with acetylcholine as a substrate.  

PubMed

An enzymatic method for the determination of serum cholinesterase (ChE) activity is described. The method is based on the liberation of acetate from acetylcholine as a substrate by ChE and the conversion of the acetate to acetylphosphate and ADP in the presence of ATP by acetate kinase. The produced ADP is coupled with pyruvate kinase and lactate dehydrogenase in the presence of phosphoenolpyruvate and NADH. The amount of NADH consumed is determined by absorbance at 340 nm. The reaction proceeds stoichiometrically, and the dilution curve is linear up to 3300 U/liter. The results obtained by this method show a good correlation with those obtained by the usual methods. PMID:4093350

Tomita, K; Kamei, S; Shiraishi, T; Hashimoto, Y; Yamanaka, M

1985-01-01

198

A Rapid, Simple Spectrophotometric Method for Simultaneous Detection of Nitrate and Nitrite  

Microsoft Academic Search

Numerous methods are available for measurement of nitrate (NO?3). However, these assays can either be time consuming or require specialized equipment (e.g., nitrate reductase, chemiluminescent detector). We have developed a method for simultaneous evaluation of nitrate and nitrite concentrations in a microtiter plate format. The principle of this assay is reduction of nitrate by vanadium(III) combined with detection by the

Katrina M. Miranda; Michael G. Espey; David A. Wink

2001-01-01

199

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

Microsoft Academic Search

A simple multivariate calibration method for analysis of two types of hypotensive mixture is described. The mixtures are composed of chlorthalidone with atenolol or chlorthalidone with both amiloride hydrochloride and atenolol. The components of the mixtures result in substantial spectral overlapbetween 87.5 and 91.0%. Resolution of the mixtures under investigation has been accomplished mainly by using CLS and PCR methods.

Abd El-Maaboud I. Mohamed; Hesham Salem

2005-01-01

200

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, pH4.4). Quantitation was achieved

Alaa El-Gindy; Samy Emara; Ahmed Mostafa

2005-01-01

201

Spectrophotometric methods for the determination of anti-emetic drugs in bulk and in pharmaceutical preparations.  

PubMed

Four rapid, simple, reproducible and sensitive methods (A-D) for assaying domperidone (I) and metoclopramide (II) in a bulk sample and in dosage forms were investigated. The first and second methods, A and B, are based on the oxidation of I and/or II by Fe3+ in the presence of o-phenanthroline (o-phen) or bipyridyl (bipy). The formation of tris-complex upon reactions with Fe3+-o-phen and/or Fe3+-bipy mixture in an acetate buffer solution of the optimum pH-values was demonstrated. Methods C and D involve the addition of excess Ce4+ and the determination of unreacted oxidant by a decrease of the red color of chromotrope 2R (C2R) at a suitable lambda(max) of 528 nm for method C, or a decrease in the orange pink color of Rhodamine 6G (Rh6G) at a suitable lambda(max) value of 525 nm for method D. A regression analysis of Beer-Lambert plots showed a good correlation in the concentration range of 0.2-5.8 microg ml(-1). The apparent molar absorptivity, Sandell sensitivity, detection and quantification limits were calculated. For a more accurate analysis, the Ringbom optimum concentration ranges are 0.35-5.6 microg ml(-1). The developed methods were successfully applied to the determination of domperidone and metoclopramide in bulk and pharmaceutical preparations without any interference from common excipients. PMID:12769377

Amin, Alaa S; Ragab, Gamal H

2003-05-01

202

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

PubMed Central

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

Turak, Fatma; Din, Mithat; Dlger, znur; zgr, Mahmure Ustun

2014-01-01

203

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  

Microsoft Academic Search

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

Erdal Din; Emine Baydan; Murat Kanbur; Feyyaz Onur

2002-01-01

204

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

PubMed

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 of solutions obtained from electrolysis of substituted phenols on antimony-doped tin oxide (SnO(2)--Sb) showed that an electron acceptor substituting group favored the aromatic ring opening reaction, preventing formation of intermediate quinone during oxidation. PMID:19922974

Vargas, Ronald; Borrs, Carlos; Mostany, Jorge; Scharifker, Benjamin R

2010-02-01

205

Kinetic spectrophotometric method for the determination of ranitidine and nizatidine in pharmaceuticals.  

PubMed

An accurate and simple kinetic method is described for the determination of ranitidine and nizatidine in pure form and in pharmaceuticals. The method is based on the reaction of the compounds with 7-chloro-4-nitrobenz-2-oxa-1,3-diazole in pH 7.4 borate buffer at 60 degrees C for a fixed time of 25 min for both compounds. The absorbance of the reaction product is measured at 495 nm for ranitidine and nizatidine. Calibration graphs were linear over the concentration range of 2-20 microg/mL, with limits of detection of 0.13 (3.7 x 10(-7) M) and 0.25 microg/mL (7.5 x 10(-7) M) for ranitidine and nizatidine, respectively. The proposed method was applied successfully to the determination of ranitidine in tablets and ampoules with average recoveries of 100.26+/-0.69 and 100.29+/-0.59%, respectively, and to the determination of nizatidine in capsules with an average recovery of 104.26+/-0.44%. The results obtained are in good agreement with those obtained by the other methods used for comparison. A proposal of the reaction pathway is also presented. PMID:12477194

Walash, Mohamed I; Belal, Fathalla; Ibrahim, Fawzia; Hefnawy, Mohamed; Eid, Manai

2002-01-01

206

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

E-print Network

method had been lacking until this work. The reductive capacity of nanoparticles was defined as the mass of iron reduced from Fe3 to Fe2 by unit mass of nanoparticles, in an aqueous solution that initially contained ferric ions. To measure the reductive...

Hwang, Wonjoong

2011-10-21

207

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

NASA Astrophysics Data System (ADS)

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

Yang, Li

2014-09-01

208

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

PubMed

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

Hosseini, Mohammad Saeid; Asadi, Mohammad

2009-06-01

209

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

NASA Technical Reports Server (NTRS)

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

Giulianelli, J.

1984-01-01

210

Experimental Study of Closed System in the Chlorine Dioxide-Iodide-Sulfuric Acid Reaction by UV-Vis Spectrophotometric Method  

PubMed Central

The mole ratio r(r = [I?]0/[ClO2]0) has great influence on ClO2-I?-H2SO4 closed reaction system. By changing the initiate concentration of potassium iodide, the curve of absorbance along with the reaction time was obtained at 350?nm and 297?nm for triiodide ion, and 460?nm for iodine. The changing point of the absorbance curve's shape locates at r = 6.00. For the reaction of ClO2-I? in the absence of H2SO4, the curve of absorbance along with the reaction time can be obtained at 350?nm for triiodide ion, 460?nm for iodine. The mole ratio r is equal to 1.00 is the changing point of the curve's shape no matter at which wavelength to determine the reaction. For the reaction of ClO2-I?-H+ in different pH buffer solution, the curve of absorbance along with the reaction time was recorded at 460?nm for iodine. When r is greater than 1.00, the transition point of the curve's shape locates at pH 2.0, which is also the point of producing chlorite or chloride for chlorine dioxide at different pH. When r is less than 1.00, the transition point locates at pH 7.0. PMID:21808646

Li, Na; Shi, Laishun; Wang, Xiaomei; Guo, Fang; Yan, Chunying

2011-01-01

211

Spectrofluorimetric and spectrophotometric stability-indicating methods for determination of some oxicams using 7-chloro-4-nitrobenz-2-oxa-1,3-diazole (NBD-Cl).  

PubMed

Two sensitive and selective spectrofluorimetric and spectrophotometric stability-indicating methods have been developed for the determination of some non-steroidal anti-inflammatory oxicam derivatives namely lornoxicam (Lx), tenoxicam (Tx) and meloxicam (Mx) after their complete alkaline hydrolysis. The methods are based on derivatization of alkaline hydrolytic products with 7-chloro-4-nitrobenz-2-oxa-1,3-diazole (NBD-Cl). The products showed an absorption maximum at 460 nm for the three studied drugs and fluorescence emission peak at 535 nm in methanol. The color was stable for at least 48 h. The optimum conditions of the reaction were investigated and it was found that the reaction proceeds quantitatively at pH 8, after heating in a boiling water bath for 30 min. The methods were found to be linear in the ranges of 1-10 microg ml(-1) for Lx and Tx and 0.5-4.0 microg ml(-1) for Mx for spectrophotometric method, while 0.05-1.0 microg ml(-1) for Lx and Tx and 0.025-0.4 microg ml(-1) for Mx for the spectrofluorimetric method. The validity of the methods was assessed according to USP guidelines. Statistical analysis of the results revealed high accuracy and good precision. The suggested procedures could be used for the determination of the above mentioned drugs in pure and dosage forms as well as in the presence of their degradation products. PMID:16651760

Taha, Elham Anwer; Salama, Nahla Nour; Fattah, Laila El-Sayed Abdel

2006-05-01

212

Spectrophotometric and TLC-densitometric methods for the simultaneous determination of Ezetimibe and Atorvastatin calcium  

PubMed Central

Three sensitive methods were developed for simultaneous determination of Ezetimibe (EZB) and Atorvastatin calcium (ATVC) in binary mixtures. First derivative (D1) spectrophotometry was employed for simultaneous determination of EZB (223.8nm) and ATVC (233.0nm) with a mean percentage recovery of 100.231.62 and 99.580.84, respectively. Linearity ranges were 10.0030.00?gmL?1 and 10.0035.00?gmL?1, respectively. Isosbestic point (IS) spectrophotometry, in conjunction with second derivative (D2) spectrophotometry was employed for analysis of the same mixture. Total concentration was determined at IS, 224.6nm and 238.6nm over a concentration range of 10.0035.00?gmL?1 and 5.0030.00?gmL?1, respectively. ATVC concentration was determined using D2 at 313.0nm (10.0035.00?gmL?1) with a mean recovery percentage of 99.721.36, while EZB was determined mathematically at 224.6nm (99.751.43) and 238.6nm (99.800.95). TLC-densitometry was employed for the determination of the same mixture; 0.100.60?gband?1 for both drugs. Separation was carried out on silica gel plates using diethyl etherethyl acetate (7:3v/v). EZB and ATVC were resolved with Rf values of 0.78 and 0.13. Determination was carried out at 254.0nm with a mean percentage recovery of 99.771.30 and 99.860.97, respectively. Methods were validated according to ICH guidelines and successfully applied for analysis of bulk powder and pharmaceutical formulations. Results were statistically compared to a reported method and no significant difference was noticed regarding accuracy and precision.

Baghdady, Yehia Z.; Al-Ghobashy, Medhat A.; Abdel-Aleem, Abdel-Aziz E.; Weshahy, Soheir A.

2012-01-01

213

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

E-print Network

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

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

2013-01-01

214

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

PubMed

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

Mohamed, Heba M

2014-10-28

215

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

NASA Astrophysics Data System (ADS)

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

Mohamed, Heba M.

2015-02-01

216

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

217

Simultaneous spectrophotometric determination of Sn(II) and Sn(IV) by mean centering of ratio kinetic profiles and partial least squares methods.  

PubMed

Two spectrophotometric methods are described for the simultaneous determination of binary mixtures of Sn(II) and Sn(IV) in water samples and fruit juice samples, without prior separation steps, using the mean centering of ratio kinetic profiles and partial least squares (PLS) methods. The methods are based on the difference in the rate of the reactions of Sn(II) and Sn(IV) with pyrocatechol violet at pH 4.0. The methods allow rapid and accurate determination of Sn(II) and Sn(IV). The analytical characteristics of the methods for the simultaneous determination of binary mixtures of Sn(II) and Sn(IV) were calculated. The results showed that the methods were capable to simultaneous determination of 0.1-1.80 mg L(-1) each of cations. The proposed methods were successfully applied to the simultaneous determination of Sn(II) and Sn(IV)in an orange juice sample. PMID:19071842

Madrakian, Tayyebeh; Afkhami, Abbas; Moein, Roshanak; Bahram, Morteza

2007-07-31

218

Evaluation of a direct spectrophotometric method for the rapid determination of ascorbate and dehydroascorbate in blood using ascorbate oxidase.  

PubMed

The application of a technique for the direct spectrophotometric determination of ascorbate and dehydroascorbate in blood samples is described. The reliability of the test system and various disturbing factors are assessed. It is concluded that the technique possesses a high specificity and that interferences by various biochemicals and metabolic intermediates are low. The lowest ascorbate concentration detectable in plasma by this assay is estimated to be about 1 mumol/l. PMID:3790252

Wunderling, M; Paul, H H; Lohmann, W

1986-10-01

219

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

2012-01-01

220

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 0.0551.373??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 0.1183.534??g?mL?1 range with a detection limit of 0.04??g?mL?1 and molar absorptivity, ? of 2.3 104?L mol?1 cm?1. Highly sensitive and selective first-, second- and third-order derivative methods are described for the determination of iron and cobalt. A simultaneous second-order derivative spectrophotometric method is proposed for the determination of these metals. All the proposed methods are successfully employed in the analysis of various biological, water, and alloy samples for the determination of iron and cobalt content. PMID:22505925

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

2012-01-01

221

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

Microsoft Academic Search

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

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

2000-01-01

222

Novel oxidation reaction of prochlorperazine with bromate in the presence of synergistic activators and its application to trace determination by flow injection/spectrophotometric method.  

PubMed

A simple and fast flow injection spectrophotometric method for the determination of bromate in water samples was developed. The detection system is based on the oxidation of prochlorperazine (PCP) with bromate in strongly acidic medium. Large amounts of chloride and bromide was found, for the first time, to act as an activator, and to enhance the sensitivity for bromate detection. The oxidation product of PCP gives pink color, which can be used to monitor the reaction spectrophotometrically at 525 nm. Under the optimal conditions, the method is selective; only nitrite, chlorite and hypochlorite can interfere with the determination of bromate. The elimination of these three ions is discussed. The calibration graph for bromate determination was linear in the range of 10-130 microg L(-1) with a detection limit of 2.3 microg L(-1). The repeatability was satisfactory, with the relative standard deviation of 1.1% (25 microg L(-1), n=10). The sample throughput was 44 h(-1). The proposed method was found to be highly reliable for screening drinking waters containing bromate, which is above or below legislation limit of 10 microg L(-1). PMID:17723757

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

2006-10-27

223

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

PubMed

Simple, rapid and accurate high performance liquid chromatographic (HPLC) and spectrophotometric methods are described for determination of antihistaminic acrivastine in capsules. The first method (method A) is based on accurate, sensitive and stability indicating chromatographic separation method. Chromolith Performance RP-18e column, a relatively new packing material consisting of monolithic rods of highly porous silica, was used as stationary phase applying isocratic binary mobile phase of ACN and 25 mM NaH2PO4 pH 4.0 in the ratio of 22.5:77.5 at flow rate of 5.0 mL/min and 40C. A diode array detector was used at 254 nm for detection. The elution time of acrivastine was found to be 2.0800.032. The second and third methods (methods B and C) are based on the oxidation of acrivastine with excess N-bromosuccinimide (NBS) and determination of the unconsumed NBS with, metol-sulphanilic acid (?max: 520 nm) or amaranth dye (?max: 530 nm). The reacted oxidant corresponds to the drug content. Beer's law is obeyed over the concentration range 1.563-50, 2.0-20 and 1.0-10 ?g mL(-1) for methods A, B and C, respectively. The limits of detection and quantitation were 0.40, 0.292 and 0.113 ?g mL(-1) and 0.782, 0.973 and 0.376 ?g mL(-1) for methods A, B and C, respectively. The HPLC method was validated for system suitability, linearity, precision, limits of detection and quantitation, specificity, stability and robustness. Stability tests were done through exposure of the analyte solution for four different stress conditions and the results indicate no interference of degradants with HPLC-method. The proposed methods was favorably applied for determination of acrivastine in capsules formulation. Statistical comparison of the obtained results from the analysis of the studied drug to those of the reported method using t- and F-tests showed no significant difference between them. PMID:24813276

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

2014-09-15

224

Simultaneous determination of metformin hydrochloride and pioglitazone hydrochloride in binary mixture and in their ternary mixture with pioglitazone acid degradate using spectrophotometric and chemometric methods.  

PubMed

In this work two well known oral hypoglycemic drugs that are administered in combination for patients with type-II diabetes were simultaneously determined. Several spectrophotometric methods were developed and validated for the determination of metformin hydrochloride (MET), pioglitazone hydrochloride (PIO) and pioglitazone acid degradate (PIO Deg). Derivative, ratio derivative, isosbestic and chemometric-assisted spectrophotometric methods were developed. The first derivative (D(1)) method was used for the determination of MET in the range of 5-30 microg x mL(-1) and PIO in the range of 10-90 microg x mL(-1) by measuring the peak amplitude at 247 nm and 280 nm, respectively. The concentration of PIO was calculated directly at 268 nm. The first derivative of ratio spectra (DD(1)) method used the peak amplitudes at 238 nm and 248.6 nm for the determination of MET in the range of 5-30 microg x mL(-1). In the isosbestic point method (ISO), the total mixture concentration was calculated by measuring the absorbance at 254.6 nm. Classical least squares (CLS), principal component regression (PCR) and partial least squares (PLS-2) were used for the quantitative determination of MET, PIO and PIO Deg. The methods developed have the advantage of simultaneous determination of the cited components without any pre-treatment. Resolution and quantitative determination of PIO degradate with a minimum concentration of 3 microg x mL(-1) in drug samples was done. The proposed methods were successfully used to determine each drug and the acid degradate in a laboratory-prepared mixture and pharmaceutical preparations. The results were statistically compared using one-way analysis of variance (ANOVA). The methods developed were satisfactorily applied to the analysis of the two drugs in pharmaceutical formulations. PMID:20355212

Hegazy, Maha A; El-Ghobashy, Mohamed R; Yehia, Ali M; Mostafa, Azza A

2009-07-01

225

A method for precomputing effective absorption coefficients from satellite measurements of backscattered UV radiation  

NASA Astrophysics Data System (ADS)

This paper presents a method for computing the effective absorption coefficients for ozone and Rayleigh scattering from satellite measurements of backscattered UV solar radiation. Values of the effective absorption coefficients for ozone and Rayleigh scattering were calculated for polar-zone summer, moderate-zone winter, moderate-zone summer, and the tropics for 12 different wavelength channels. Using these coefficients, the calculations of solar UV radiation (backscattered by the terrestrial atmosphere within the ozone absorption band and measured with SBUV/TOMS instruments) are reduced to calculations of the intensity of monochromatic radiation.

Ishov, A. G.; Kozina, T. V.

1990-10-01

226

A simple spectrophotometric method for the determination of cadmium in industrial, environmental, biological and soil samples using 5,7-dibromo-8-hydroxyquinoline.  

PubMed

A very simple, ultra-sensitive and highly selective non-extractive spectrophotometric method for the determination of trace amount of cadmium using 5,7-dibromo-8-hydroxyquinoline (DBHQ) has been developed. DBHQ reacts in a slightly acidic solution with cadmium to give a deep greenish-yellow chelate, which has an absorption maximum at 396 nm. The average molar absorption co-efficient and Sandell's sensitivity were found to be 5.3 x 10(3) L mol(-1) cm(-2) and 20 ng cm(-2) of Cd, respectively. Linear calibration graphs were obtained for 0.1-30 microg mL(-1) of Cd. A large excess of over 50 cations, anions and some common complexing agents do not interfere with the determination. The method was successfully used in the determination of cadmium in several Standard Reference Materials as well as in some environmental waters, biological and soil samples. PMID:15228125

Ahmed, M Jamaluddin; Chowdhury, M Tauhidul Islam

2004-06-01

227

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

NASA Astrophysics Data System (ADS)

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

Niazi, Ali; Khorshidi, Neda; Ghaemmaghami, Pegah

2015-01-01

228

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

PubMed

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

Niazi, Ali; Khorshidi, Neda; Ghaemmaghami, Pegah

2015-01-25

229

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

PubMed Central

The recently approved angiotensin II receptor blocker, azilsartan medoxomil (AZL), was determined spectrophotometrically and spectrofluorimetrically in its combination with chlorthalidone (CLT) in their combined dosage form. The UV-spectrophotometric technique depends on simultaneous measurement of the first derivative spectra for AZL and CLT at 286 and 257 nm, respectively, in methanol. The spectrofluorimetric technique depends on measurement of the fourth derivative of the synchronous spectra intensities of AZL in presence of CLT at 298 nm in methanol. The effects of different solvents on spectrophotometric and spectrofluorimetric responses were studied. For, the spectrofluorimetric study, the effect of pH and micelle-assisted fluorescence enhancement were also studied. Linearity, accuracy, and precision were found to be satisfactory over the concentration ranges of 850 ?g mL?1 and 220 ?g mL?1 for AZL and CLT, respectively, in the spectrophotometric method as well as 0.010.08 ?g mL?1 for AZL in the spectrofluorimetric method. The methods were successfully applied for the determination of the studied drugs in their co-formulated tablets. The developed methods are inexpensive and simple for the quality control and routine analysis of the cited drugs in bulk and in pharmaceuticals. PMID:24855334

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

2014-01-01

230

A new method for rapid determination of carbohydrate and total carbon concentrations using UV spectrophotometry.  

PubMed

A new UV spectrophotometry based method for determining the concentration and carbon content of carbohydrate solution was developed. This method depends on the inherent UV absorption potential of hydrolysis byproducts of carbohydrates formed by reaction with concentrated sulfuric acid (furfural derivatives). The proposed method is a major improvement over the widely used Phenol-Sulfuric Acid method developed by DuBois, Gilles, Hamilton, Rebers, and Smith (1956). In the old method, furfural is allowed to develop color by reaction with phenol and its concentration is detected by visible light absorption. Here we present a method that eliminates the coloration step and avoids the health and environmental hazards associated with phenol use. In addition, avoidance of this step was shown to improve measurement accuracy while significantly reducing waiting time prior to light absorption reading. The carbohydrates for which concentrations and carbon content can be reliably estimated with this new rapid Sulfuric Acid-UV technique include: monosaccharides, disaccharides and polysaccharides with very high molecular weight. PMID:23911443

Albalasmeh, Ammar A; Berhe, Asmeret Asefaw; Ghezzehei, Teamrat A

2013-09-12

231

Simultaneous Determination of 6-Mercaptopurine and its Oxidative Metabolites in Synthetic Solutions and Human Plasma using Spectrophotometric Multivariate Calibration Methods  

PubMed Central

Introduction 6-Mercaptopurine (6MP) is an important chemotherapeutic drug in the conventional treatment of childhood acute lymphoblastic leukemia (ALL). It is catabolized to 6-thiouric acid (6TUA) through 8-hydroxo-6-mercaptopurine (8OH6MP) or 6-thioxanthine (6TX) intermediates. Methods High-performance liquid chromatography (HPLC) is usually used to determine the contents of therapeutic drugs, metabolites and other important biomedical analytes in biological samples. In the present study, the multivariate calibration methods, partial least squares (PLS-1) and principle component regression (PCR) have been developed and validated for the simultaneous determination of 6MP and its oxidative metabolites (6TUA, 8OH6MP and 6TX) without analyte separation in spiked human plasma. Mixtures of 6MP, 8-8OH6MP, 6TX and 6TUA have been resolved by PLS-1 and PCR to their UV spectra. Results Recoveries (%) obtained for 6MP, 8-8OH6MP, 6TX and 6TUA were 94.5-97.5, 96.6-103.3, 95.1-96.9 and 93.4-95.8, respectively, using PLS-1 and 96.7-101.3, 96.2-98.8, 95.8-103.3 and 94.3-106.1, respectively, using PCR. The NAS (Net analyte signal) concept was used to calculate multivariate analytical figures of merit such as limit of detection (LOD), selectivity and sensitivity. The limit of detections for 6MP, 8-8OH6MP, 6TX and 6TUA were calculated to be 0.734, 0.439, 0.797 and 0.482 ?mol L-1, respectively, using PLS and 0.724, 0.418, 0783 and 0.535 ?mol L-1, respectively, using PCR. HPLC was also applied as a validation method for simultaneous determination of these thiopurines in the synthetic solutions and human plasma. Conclusion Combination of spectroscopic techniques and chemometric methods (PLS and PCR) has provided a simple but powerful method for simultaneous analysis of multicomponent mixtures PMID:23678408

Sorouraddin, Mohammad-Hossein; Khani, Mohammad-Yaser; Amini, Kaveh; Naseri, Abdolhossein; Asgari, Davoud; Rashidi, Mohammad-Reza

2011-01-01

232

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

233

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

234

Determination of p-aminosalicylic acid and m-aminophenol by derivative UV-spectrophotometry.  

PubMed

A direct method for the simultaneous determination of p-aminosalicylic acid (PAS) and its major decomposition product, m-aminophenol (MAP), is described. The analysis is based on the use of derivative UV-spectrophotometry and is a rapid procedure which gives accurate and precise results. A simple purity test which utilizes the third derivative spectrum is also reported and compared with the USP XX spectrophotometric method for the estimation of MAP in PAS formulations. PMID:16867404

Vetuschi, C; Ragno, G; Mazzeo, P

1988-01-01

235

Development and application of a novel UV method for the analysis of ascorbic acid  

Microsoft Academic Search

A UV method for the analysis of ascorbic acid with methanol as solvent to prepare a sample has been developed and applied. The effect of copper(II) concentrations on the oxidation of ascorbic acid in aqueous solution has been studied in detail, and the regularities of ascorbic acid oxidation in methanol, USP phosphate buffer (pH 2.50) and de-ionized water have been

Wenming Zeng; Frank Martinuzzi; Alexander MacGregor

2005-01-01

236

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

237

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

238

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

239

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

PubMed

A flow-injection indirect spectrophotometric method for the determination of ascorbic acid (AA) in pharmaceutical preparations is proposed. The method is based on the reduction of iron(III) to iron(II) by the AA, and by the subsequent reaction of the produced iron(II) with 2,4,6-tripyridyl-s-triazine (TPTZ) in buffered medium (pH=3.6) to form a coloured complex (?(max)=593nm). The three-line manifold with one reaction coil was used. The linear range of the method is from 0.08 to 10?M of ascorbic acid, with the detection limit 24nM of AA. The proposed method is simple, rapid (sampling rate of 180 samples per hour), sensitive and reproducible (RSD 0.8%, n=100). The proposed method is very selective, because only the reducing substances with standard (formal) potentials lower than 0.6V would have the thermodynamic predisposition to interfere in the proposed method. Tested reducing substances (thiol compounds) did not give serious errors when present at the same concentrations as the ascorbic acid. The proposed method can be applied for the determination of AA in pharmaceutical preparations, down to picomolar quantity. PMID:22817946

Kukoc-Modun, Lea; Biocic, Maja; Radi?, Njegomir

2012-07-15

240

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

PubMed

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

Al Okab, Riyad Ahmed

2013-02-15

241

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

PubMed Central

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

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

2013-01-01

242

Spectrophotometric and reversed-phase high-performance liquid chromatographic methods for simultaneous determination of escitalopram oxalate and clonazepam in combined tablet dosage form.  

PubMed

Simple, accurate, precise, and sensitive ultraviolet spectrophotometric and reversed-phase high-performance liquid chromatographic (RP-HPLC) methods for simultaneous estimation of escitalopram oxalate (ESC) and clonazepam (CLO) in combined tablet dosage form have been developed and validated. The spectroscopic method employs an absorbance correction method using 238.6 and 308 nm as 2 wavelengths for estimation with methanol and water as solvents. Beer's law is obeyed in the concentration range of 10.0-50.0 and 0.5-3.0 micro/mL for ESC and CLO, respectively. The RP-HPLC method uses a Jasco HPLC system with HiQ SiL C18 column (250 x 4.6 mm id) acetonitrile-0.005 M tetrabutylammonium hydrogen sulfate (55 + 45, v/v) as the mobile phase, and satranidazole as an internal standard. The detection was carried out using an ultraviolet detector set at 287 nm. For the HPLC method, Beer's law is obeyed in the concentration range of 10.0-60.0 and 0.5-3.0 microg/mL for ESC and CLO, respectively. Both methods have been successfully applied for the analysis of the drugs in a pharmaceutical formulation. Results of analysis were validated statistically and by recovery studies. PMID:18376583

Gandhi, Santosh Vilashchand; Dhavale, Nilesh Dnyandev; Jadhav, Vijay Yeshawantrao; Sabnis, Shweta Sadanand

2008-01-01

243

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 Ins G S; Estela, Jos Manuel; Segundo, Marcela A; Cerd, Vctor

2011-06-15

244

SPECTROPHOTOMETRIC DETERMINATION OF URANIUM IN ORES WITH 8QUINOLINOL  

Microsoft Academic Search

A method for the sensitive and rapid spectrophotometric determination of ; uranium in ores using 8-quinolinol was developed. Uranium is separated by ; extraction with tributylphosphate-kerosene from nitric acid solution. After the ; back-extraction of uranium with ammonium carbonate solution, uranium is ; determined spectrophotometrically with 8-quinolinol. When 1 gram of sample is ; taken, as little as 0.005% of

K. Motojima; H. Yoshida; T. Imahashi

1962-01-01

245

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

PubMed

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

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

2013-01-01

246

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 415nm. The carrier solution used was 1??10(-5)M 2', 3, 4', 5, 7-pentahydroxyflavone in 0.1M HAc/Ac(-) buffer solution at pH4.5. Parameters that affect simultaneously the determination of iron (II) and interfering ions were tested. The relative standard deviation for the determination of 50?gL(-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?gL(-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

2013-03-01

247

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

PubMed

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

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

2014-07-10

248

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

PubMed Central

A simple and new simultaneous fourth derivative spectrophotometric method is proposed for the analysis of a two-component system containing cobalt(II) and nickel(II) without separation using 2-hydroxy-3-methoxy benzaldehyde thiosemicarbazone (HMBATSC) as a chromophoric reagent. The reagent reacts with cobalt(II) and nickel(II) at pH 6.0, forming soluble brown and yellow colored species, respectively. Cobalt(II) and nickel(II) present in themixture are simultaneously determined without solving the simultaneous equations bymeasuring the fourth derivative amplitudes at 468.5 nm and 474.5 nm, respectively. The derivative amplitudes obey Beer's law at 468.5 nm and 474.5 nm for Co(II) and Ni(II) in the range 0.0593.299 ?g mL?1 and 0.0583.285 ?g mL?1 respectively. A large number of foreign ions do not interfere in the present method. The present simultaneous method is used for the determination of micro amounts of cobalt in biological samples, nickel in plant samples, and in some alloy steels and soil sample. PMID:17671609

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

2007-01-01

249

Intensity calibration of a vacuum UV spectrometer by using the line ratio method  

NASA Astrophysics Data System (ADS)

The line ratio method is employed to determine the relative efficiency of a vacuum UV spectrometer in the wavelength region from 38 to 118 nm. The measured line ratio (N II, 74.4/85.8 nm) disagrees with the theoretical values determined by Kelly (1964), Luken and Sinanoglu (1976), and Beck and Nicolaides (1977). The line ratio (O II, 71.9/79.7 nm is in good agreement with experimental data by Feldmann et al. (1981), Morrison et al. (1989), and Ryan et al. (1989), and with most of the calculations.

Bastert, Axel; Bukow, Hans H.; von Buttlar, Haro

1992-11-01

250

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

PubMed

Orthohydroxypropiophenoneisonicotinoylhydrazone (OHPINH) is proposed as a new sensitive reagent for the spectrophotometric determination of aluminum(III). OHPINH formed a greenish-yellow colored complex with aluminum(III) in buffer solutions of 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 the reagent was chosen as blank and the absorbance of the reagent at this wavelength is negligible; the molar absorptivity and Sandell's sensitivity being 0.6371x10(4) L mol(-1) cm(-1) and 4.234x10(-3) microg cm(-2), respectively. The system obeys Beer's law in the range of 0.5-3.5 microg mL(-1) with excellent linearity in terms of the correlation coefficient value of 0.999. Most of the common metal ions generally found associated with aluminum(III) do not interfere. The repeatability of the method was checked by finding the relative standard deviation. The developed method has been successfully employed for the determination of aluminum(III) environmental matrices like medicinal and leafy samples, alloys, and synthetic mixtures. PMID:19058020

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

2010-01-01

251

A sensitive spectrophotometric method for the determination of H2-receptor antagonists by means of N-bromosuccinimide and p-aminophenol.  

PubMed

A simple, accurate and sensitive spectrophotometric method for determination of H2-receptor antagonists: cimetidine (CIM), famotidine (FAM), nizatidine (NIZ), and ranitidine hydrochloride (RAN) has been fully developed and validated. The method was based on the reaction of these drugs with NBS and subsequent measurement of the excess N-bromosuccinimide by its reaction with p-aminophenol to give a violet colored product (lambda max at 552 nm). Decrease in the absorption intensity (Delta A) of the colored product, due to the presence of the drug, was correlated with its concentration in the sample solution. Different variables affecting the reaction were carefully studied and optimized. Under optimal conditions, linear relationships with good correlation coefficients (0.9988-0.9998) were found between Delta A values and the corresponding concentrations of the drugs in a concentration range of 8-30, 6-22, 6-25, and 4-20 microg mL(-1) for CIM, FAM, NIZ, and RAN, respectively. Limits of detection were 1.22, 1.01, 1.08, and 0.74 microg mL(-1) for CIM, FAM, NIZ, and RAN, respectively. The method was validated in terms of accuracy, precision, ruggedness, and robustness; the results were satisfactory. The proposed method was successfully applied to the analysis of the above mentioned drugs in bulk substance and in pharmaceutical dosage forms; percent recoveries ranged from 98.5 +/- 0.9 to 102.4 +/- 0.8% without interference from the common excipients. The results obtained by the proposed method were comparable with those obtained by the official methods. PMID:18337210

Darwish, Ibrahim A; Hussein, Samiha A; Mahmoud, Ashraf M; Hassan, Ahmed I

2008-03-01

252

Development and validation of spectrophotometric and HPTLC methods for simultaneous determination of rosiglitazone maleate and metformin hydrochloride in the presence of interfering matrix excipients.  

PubMed

Two simple methods have been developed and validated for the simultaneous determination of rosiglitazone maleate (ROS) and metformin hydrochloride (MET) in synthetic mixtures and coated tablets in a ratio of 1:250 (ROS:MET). The first method was a spectrophotometric one. The minor component, ROS was determined by measuring the values of absorbance at ?max 312?nm and the D1 amplitudes at 331?nm where MET shows no absorption contribution. However, absorbance interferences from tablet excipients were successfully corrected by D1 at 331?nm zero-crossing technique. Study of spectral interference from tablet excipients was included in the text. Standard curves for Amax and D1 methods were in the concentration range 20.0-80.0??g?mL(-1). The major component, MET was determined both in binary mixtures and tablets by measuring its Amax at 236?nm. Extensive dilution eliminated any absorption contribution from the coexisting ROS or tablet matrix. Standard curves showed linearity in the concentration range 4.0-12.8??g?mL(-1). The second method was based on high performance thin layer chromatography (HPTLC) separation of the two drugs followed by densitometric measurements of their spots at 230?nm. The separation was carried out on Merck HPTLC aluminium sheets of silica gel 60 F254 using methanol:water:NH4Cl 1% w/v (5:4:1 v/v/v) as the mobile phase. Linear calibration graphs of peak area values were obtained versus concentrations in the range of 0.4-2.0??g?band(-1) and 20.0-100.0??g?band(-1) for ROS and MET, respectively. According to International Conference on Harmonisation (ICH) guidelines, different validation parameters were verified for the two methods and presented. PMID:23829222

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

2014-09-01

253

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; L, Hai-Bing; Zheng, Wan-Guo; Zu, Xiao-Tao

2012-06-01

254

THE SPECTROPHOTOMETRIC DETERMINATION OF URANIUM WITH DIBENZOYLMETHANE  

Microsoft Academic Search

Description is given of a simple direct spectrophotometric determination ; of uranium with dibenzoylmethane in combination with tributyl phosphate, which is ; selected as the extractant of uranium because of its popularity. The procedure ; was applied to the determination of U in U ores and in monazite. One advantage ; of the method is that change in acidity does

Yoshimi Umezaki

1963-01-01

255

Reliability-targeted HPLC-UV method validation--a protocol enrichment perspective.  

PubMed

Method validation is important in analytical chemistry to obtain the reliability of an analytical method. Guidelines provided by the regulatory bodies can be used as a general framework to assess the validity of a method. Since these guidelines do not focus on the reliability of analytical results exclusively, this study was aimed to combine a few recently evolved strategies that may render analytical method validation more reliable and trustworthy. In this research, the analytical error function was determined by appropriate polynomial regression statistics that determine the range of analyte concentration that may lead to more accurate measurements by producing the least possible total error in the assay and can be regarded as a reliable weighting method. The reliability of the analytical results over a particular concentration range has been proposed by a Bayesian probability study. In order to ensure the applicability of this approach, it was applied for the validation of an HPLC-UV assay method dedicated to the quantification of cefepime and tazobactam in human plasma. A comparison between the newer approach and the usual method validation revealed that the application of analytical error function and Bayesian analysis at the end of the validation process can produce significant improvements in the analytical results. PMID:24302678

Dharuman, Joghee Gowder; Vasudevan, Mahalingam

2014-02-01

256

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

PubMed Central

The determination of sodium cromoglicate (SCG) and fluorometholone (FLU) in ophthalmic solution was developed by simple, sensitive and precise methods. Three spectrophotometric methods were applied: absorptivity factor (a-Factor method), absorption factor (AFM) and mean centering of ratio spectra (MCR). The linearity ranges of SCG were found to be (2.535?g/mL) for (a-Factor method) and (MCR); while for (AFM), it was found to be (7.550?g/mL). The linearity ranges of FLU were found to be (416?g/mL) for (a-Factor method) and (AFM); while for (MCR), it was found to be (216?g/mL). The mean percentage recoveries/RSD for SCG were found to be 100.31/0.90, 100.23/0.57 and 100.43/1.21; while for FLU, they were found to be 100.11/0.56, 99.97/0.35 and 99.94/0.88 using (a-Factor method), (AFM) and (MCR), respectively. A TLC-spectrodensitometric method was developed by separation of SCG and FLU on silica gel 60 F254 using chloroform:methanol:toluene:triethylamine in the ratio of (5:2:4:1v/v/v/v) as developing system, followed by spectrodensitometric measurement of the bands at 241nm. The linearity ranges and the mean percentage recoveries/RSD were found to be (0.44.4?g/band), 100.24/1.44 and (0.21.6?g/band), 99.95/1.50 for SCG and FLU, respectively. A comparative study was conducted between the proposed methods to discuss the advantage of each method. The suggested methods were validated in compliance with the ICH guidelines and were successfully applied for the determination of SCG and FLU in their laboratory prepared mixtures and commercial ophthalmic solution in the presence of benzalkonium chloride as a preservative. These methods could be an alternative to different HPLC techniques in quality control laboratories lacking the required facilities for those expensive techniques. PMID:24227962

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

2013-01-01

257

Antioxidant components of Viburnum opulus L. determined by on-line HPLC-UV-ABTS radical scavenging and LC-UV-ESI-MS methods.  

PubMed

Antioxidant activity of the juice and seed and skin extracts prepared with methanol, acetonitrile, and water of Viburnum opulus L. grown in Eastern Black Sea Region were studied with an on-line HPLC-ABTS method and off-line antioxidant methods, among which a linear positive correlation was observed. The fruit extracts were analysed with the HPLC-UV method optimised with 14 standard phenolics. Identification of the phenolic components in the juice was made using an HPLC-UV-ESI-MS method. Nineteen phenolic compounds in juice were identified by comparing the retention times and mass spectra with those of the standards and the phenolics reported in the literature. The major peaks in the juice belonged to coumaroyl-quinic acid, chlorogenic acid, procyanidin B2, and procyanidin trimer. Quite different antioxidant composition profiles were obtained from the extracts with the solvents of different polarities. The antioxidant activities of the seed extracts were higher than those of the skin extracts in general. PMID:25577058

Karaelik, Aya Akta?; Kk, Murat; ?skefiyeli, Zeynep; Aydemir, Sezgin; De Smet, Seppe; Miserez, Bram; Sandra, Patrick

2015-05-15

258

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

259

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. PMID:24082696

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

2013-01-01

260

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?g/ml) lead to concentrations in urine being about 100 times higher allowing the use of less sensitive analytical techniques that were used especially in the early years after 2-PAM was introduced. In this time (mid-1950s until the end of the 1970s) 2-PAM was most often analyzed by either paper chromatography or simple UV spectroscopic techniques omitting any sample separation step. These methods were displaced completely after the establishment of column liquid chromatography in the early 1980s. Since then, diverse techniques including cation exchange, size-exclusion, reversed-phase, and ligand-exchange chromatography have been introduced. Today, the most popular method for 2-PAM quantification is ion pair chromatography often combined with UV detection representing more than 50% of all column chromatographic procedures published. Furthermore, electrophoretic approaches by paper and capillary zone electrophoresis have been successfully used but are seldom applied. This review provides a commentary and exhaustive summary of analytical techniques applied to detect 2-PAM in pharmaceutical formulations and biological samples to characterize stability and pharmacokinetics as well as decomposition and biotransformation products. Separation techniques as well as diverse detectors are discussed in appropriate detail allowing comparison of individual preferences and limitations. In addition, novel data on mass spectrometric fragmentation of 2-PAM are provided. PMID:21953823

John, Harald; Blum, Marc-Michael

2012-01-01

261

Titrimetric, spectrophotometric and kinetic methods for the as- say of atenolol using bromate-bromide and methyl orange  

Microsoft Academic Search

Three new methods have been developed for the determination of atenolol in bulk drug and in tablet formulation. The methods are based on the oxidation-bromina- tion reaction of the drug by bromine, generated in situ by the action of acid on ab ro- mate-bromide mixture. In the titrimetric method, the drug is treated with a known ex- cess of bromate-bromide

KANAKAPURA BASAVAIAH; UMAKANTHAPPA CHANDRASHEKAR

262

Degradation Study on Sulfasalazine and a Validated HPLC-UV Method for its Stability Testing.  

PubMed

Sulfasalazine (SSZ) was subjected to degradation under the conditions of hydrolysis (acid, alkali, and water), oxidation (30% H2O2), dry heat, and photolysis (UV-VIS light) in accordance with the ICH guidelines. An RP-HPLC method was developed to study the degradation behavior. No degradation was noted under any condition except alkaline hydrolysis where SSZ was degraded to a single minor product. SSZ was optimally resolved from this product on an XTerra() RP18 column with a mobile phase composed of methanol and an ammonium acetate buffer (10 mM, pH 7.0) (48:52, v/v) delivered at a rate of 0.8 mL/min in an isocratic mode. The method was validated and found to be linear (r(2)=0.99945), precise (%RSD <2), robust, and accurate (94-102%) in the concentration range of 0.5-50 ?g/mL of SSZ. The PDA analysis of the degraded sample revealed the SSZ peak purity to be 998.99 and the drug peak eluted with a resolution factor of >2 from the nearest resolving peak, indicating the method to be selectively stability-indicating for the drug analysis. The method was applied successfully for the stability testing of the commercially available SSZ tablets that were under varied ICH-prescribed conditions. An explanation for the unusual stability of the drug when exposed to acidic hydrolysis, despite the presence of the sulfonamide linkage, is also discussed. PMID:24959403

Saini, Balraj; Bansal, Gulshan

2014-06-01

263

Degradation Study on Sulfasalazine and a Validated HPLC-UV Method for its Stability Testing  

PubMed Central

Sulfasalazine (SSZ) was subjected to degradation under the conditions of hydrolysis (acid, alkali, and water), oxidation (30% H2O2), dry heat, and photolysis (UV-VIS light) in accordance with the ICH guidelines. An RP-HPLC method was developed to study the degradation behavior. No degradation was noted under any condition except alkaline hydrolysis where SSZ was degraded to a single minor product. SSZ was optimally resolved from this product on an XTerra RP18 column with a mobile phase composed of methanol and an ammonium acetate buffer (10 mM, pH 7.0) (48:52, v/v) delivered at a rate of 0.8 mL/min in an isocratic mode. The method was validated and found to be linear (r2=0.99945), precise (%RSD <2), robust, and accurate (94102%) in the concentration range of 0.550 ?g/mL of SSZ. The PDA analysis of the degraded sample revealed the SSZ peak purity to be 998.99 and the drug peak eluted with a resolution factor of >2 from the nearest resolving peak, indicating the method to be selectively stability-indicating for the drug analysis. The method was applied successfully for the stability testing of the commercially available SSZ tablets that were under varied ICH-prescribed conditions. An explanation for the unusual stability of the drug when exposed to acidic hydrolysis, despite the presence of the sulfonamide linkage, is also discussed. PMID:24959403

Saini, Balraj; Bansal, Gulshan

2014-01-01

264

Quantification of potential impurities by a stability indicating UVHPLC method in niacinamide active pharmaceutical ingredient  

Microsoft Academic Search

A sensitive, stability indicating reverse phase UVHPLC method has been developed for the quantitative determination of potential impurities of niacinamide active pharmaceutical ingredient. Efficient chromatographic separation was achieved on C18 stationary phase in isocratic mode using simple mobile phase. Forced degradation study confirmed that the newly developed method was specific and selective to the degradation products. Major degradation of the

Saji Thomas; Amber Bharati; Kalsang Tharpa; Ashutosh Agarwal

265

UV-visible spectroscopy as an alternative to liquid chromatography for determination of everolimus in surfactant-containing dissolution media: a useful approach based on solid-phase extraction.  

PubMed

High-throughput 96-well solid phase extraction (SPE) plate with C-18 reversed phase sorbent followed by UV-visible (UV-Vis) microplate reader was applied to the analysis of hydrophobic drugs in surfactant-containing dissolution media, which are often used to evaluate the in-vitro drug release of drug eluting stents (DES). Everolimus and dissolution medium containing Triton X-405 were selected as representatives, and the appropriate SPE conditions (adsorption, washing and elution) were investigated to obtain a practical and reliable sample clean-up. It was shown that the developed SPE procedure was capable of removing interfering components (Triton X-405 and its impurities), allowing for an accurate automated spectrophotometric analysis to be performed. The proposed UV-Vis spectrophotometric method yielded equivalent results compared to a classical LC analysis method. Linear regression analysis indicated that both methods have the ability to obtain test results that are directly proportional to the concentration of analyte in the sample within the selected range of 1.0-10 ?g/ml for everolimus, with a coefficient of correlation (r(2)) value of >0.998 and standard deviation of the residuals (Syx) of <2%. The individual recoveries of everolimus ranged from 97 to 104% for the UV-Vis spectrophotometric method and from 98 to 102 for the HPLC method, respectively. The 95% CI of the mean recovery for the UV-Vis spectrophotometric method was 99-102% and for the HPLC method was 99-101%. No statistical difference was found between the mean recoveries of the methods (p=0.42). Hence the methods are free from interference due to Triton and other chemicals present in the dissolution medium. The variation in the amount of everolimus estimated by UV-Vis spectrophotometric and HPLC methods was ?3.5%, and the drug release profiles obtained by both methods were found to be equivalent by evaluation with two-one-sided t-test (two-tailed, p=0.62; mean of differences, 0.17; 95% CI, 0.62-0.96) and similarity factor f2 (f2 value, 87). The excellent conformity of the results makes UV-Vis spectrophotometer an ideal tool for analyzing the drugs in the media containing surfactants, after SPE. The 96-well SPE plates in combination with UV-Vis microplate reader provide a high throughput method for the determination of in-vitro drug release profile of DES. Switching from HPLC to UV-Vis spectrophotometer microplate reader assay reduces the solvent consumption and labor required for the sample analyses. This directly impacts the profitability of the laboratory. PMID:22726455

Kamberi, Marika; Tran, Thu-Ngoc

2012-11-01

266

STUDIES ON THE DETERMINATION OF TRACE OF ELEMENTS IN IRON AND STEELS. VI. SPECTROPHOTOMETRIC DETERMINATION OF BERYLLIUM IN IRON AND STEEL USING ACETYL ACETONATE EXTRACTION METHOD  

Microsoft Academic Search

The extraction of beryllium-- acetylacetone complex with chloroform and ; the spectrophotometric determination of beryllium was applied for the iron and ; steel analysis. 0.25 g of sample is decomposed in 10 ml of perchloric acid, and ; when chromium content exceeds 3% most of it is evaporated as chromyl chloride. ; The solution is diluted exactly to 250 ml

S. Maekawa; Y. Yoneyama

1961-01-01

267

Spectrophotometric method for the determination of vanadium in uranium rich hydrogeochemical samples using pyridyl azo resorcinol (PAR).  

PubMed

A simple and precise method has been developed for the determination of traces of vanadium(V), using 4-(2 pyridyl azo) resorcinol, in natural water samples, containing very high concentrations of uranium. CDTA-pyrophosphate buffer has been used for masking interferants, including uranium which otherwise interferes above 125 ppb. The reaction of vanadium with PAR in the presence of buffer requires a waiting period of 45 min. The Sandell sensitivity of the method is 0.003 microg/ml, at 545 nm at an optimum pH of 6.5 +/- 0.2. The precision of the method is +/- 15% at the 100 ppb level of vanadium(V). The method has been successfully applied to a number of natural water samples during hydrogeochemical exploration. PMID:18965663

Chakrapani, G; Murty, D S; Balaji, B K; Rangaswamy, R

1993-04-01

268

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

Microsoft Academic Search

SummaryThe 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

269

UPLC-UV method for determination of risedronate in human urine.  

PubMed

This study was designed to develop a sensitive and rapid method for the quantitation of risedronate in human urine using ultra-performance liquid chromatography with ultra-violet detector (UPLC-UV) and to compare bioavailability parameter of 5, 35 and 150 mg risedronate. The mobile phase consisted of sodium phosphate buffer, 1 mM etidronate-acetonitrile (95:5, v/v), pH 9.0, and was pumped at a ?ow rate of 0.3 mL/min. Detection of risedronate in human urine by the UPLC-UV was accurate and precise from 20 ng/mL to 5 ?g/mL (a correlation coefficient of 0.99) with 97.16% in mean recovery. The intra-day accuracy was 89.17-110.43% with precision of 0.04-3.16% and the inter-day accuracy was 89.23-110.19% with precision of 1.63-9.72%. Aet (accumulated excretion amount) of risedronate in the urine after 5, 35 and 150 mg administration was 35.08, 246.67 and 1.413.85 ?g within 36 h and Umax (maximal excretion rate) was 12.11, 77.7 and 374.24 ?g/h, respectively. The assessed dose proportionality of Umax and Aet with three single doses of risedronate was found in an approximately linear manner. These results indicate that the developed simple, rapid and robust assay enables the complete processing of large samples for pharmacokinetic studies of risedronate in biological fluid. PMID:23851998

Seo, Young Hwan; Chung, Yoon Hee; Lim, Cheol-Hee; Jeong, Ji Hoon

2014-08-01

270

Differential spectrophotometric determination of mixed uranium(VI) and thorium(IV) by the stop-flow method  

SciTech Connect

From a study of the kinetics of the reaction between Th(IV) and U(VI) and Arsenazo III a method, based on the time-selection principle, has been developed for the differential deterential determination of these ions in a mixture in the ratio of 5:1.

Pogonin, V.I.; Likhonin, E.A.; Savvin, S.B.; Chibisov, A.K.

1986-10-20

271

[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

272

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...

273

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 0.130 mg L?1 and 0.0130 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 Sandells sensitivity, the limit of detection and relative standard deviation (n = 9) were found to be 5 ng cm?2, 1 ng mL?1 and 2%, respectively in aqueous micellar solutions. Its sensitivity and selectivity are remarkably higher than that of other reagents in the literature. The proposed method was successfully used in the determination of gold in several standard reference materials (alloys and steels), environmental water samples (potable and polluted), and biological samples (blood and urine), geological, soil and complex synthetic mixtures. The results obtained agree well with those samples analyzed by atomic absorption spectrophotometry (AAS). PMID:19609392

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

2008-01-01

274

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

NASA Astrophysics Data System (ADS)

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 reaction were studied and optimized. Under the optimum conditions, linear relationships with good correlation coefficients (0.9979-0.9995) were found between the absorbance and the concentration of the drug in the range 16-880 ?g ml -1. The proposed methods were applied successfully to the determination of the examined drug either in pure or pharmaceutical dosage forms with good accuracy and precision. The formation of the CT-complexes and the sites of interaction were confirmed by elemental analysis CHN, UV-vis, IR, 1H NMR and mass spectra techniques. Based on Job's method of continuous variation plots, the obtained results indicate the formation of 1:1 charge-transfer complexes with the general formula [(fluc)(acceptor)]. Statistical analysis of the obtained results showed no significant difference between the proposed method and official method.

Refat, Moamen S.; El-Didamony, Akram M.

2006-11-01

275

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

PubMed

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 pi-electron acceptors have been investigated spectrophotometrically. Different variables affecting the reaction were studied and optimized. Under the optimum conditions, linear relationships with good correlation coefficients (0.9979-0.9995) were found between the absorbance and the concentration of the drug in the range 16-880 microg ml(-1). The proposed methods were applied successfully to the determination of the examined drug either in pure or pharmaceutical dosage forms with good accuracy and precision. The formation of the CT-complexes and the sites of interaction were confirmed by elemental analysis CHN, UV-vis, IR, (1)H NMR and mass spectra techniques. Based on Job's method of continuous variation plots, the obtained results indicate the formation of 1:1 charge-transfer complexes with the general formula [(fluc)(acceptor)]. Statistical analysis of the obtained results showed no significant difference between the proposed method and official method. PMID:16527531

Refat, Moamen S; El-Didamony, Akram M

2006-11-01

276

Validated stability-indicating HPLC-UV method for simultaneous determination of glipizide and four impurities.  

PubMed

A selective stability-indicating HPLC-UV method for simultaneous determination of glipizide and four impurities (DPs I-IV) formed under hydrolytic conditions was developed and validated. The drug and impurities were resolved on an XTerra C18 column (250 x 4.5 mm id) in a single gradient run using buffer (0.005 M KH2PO4; pH 3.0)-methanol (60 + 40, v/v; mobile phase A) and (20 + 80, v/v; mobile phase B) at a flow rate of 0.5 mL/min with 230 nm detection wavelength. The method was linear across concentration ranges of 0.2-100, 0.1-100, 0.5-100, 0.2-100, and 0.1-50 microg/mL for glipizide and DPs I-IV, respectively. The RSD for intraday and interday precision for the drug and impurities was < 1 and < 1.2%, respectively. Satisfactory recoveries (96.58-99.97%) of each of the three concentrations selected across the linearity range of each analyte were obtained, proving the method was sufficiently accurate. The LOD was 0.07, 0.05, 0.16, 0.08, and 0.05 microg/mL and the LOQ was 0.20, 0.14, 0.50, 0.23, and 0.14 microg/mL for the drug and DPs I-IV, respectively. Each peak was resolved with resolution of > 2 from the nearest peak. Insignificant changes in retention time (< 4%) and calculated amount (< 1.65%) of drug and each impurity upon small but deliberate changes in various chromatographic parameters were observed, suggesting the method was robust. The method was applied successfully to stability testing of glipizide tablets. PMID:21563686

Gupta, Sakshi; Bansal, Gulshan

2011-01-01

277

Extraction and spectrophotometric determination of uranium in phosphate fertilizers  

Microsoft Academic Search

An extraction and spectrophotometric method for determination of trace amounts of uranium in phosphate fertilizers is described. It is based on the extraction of uranium with trioctylphosphine oxide in benzene and the spectrophotometric determination of uranium with Arsenazo III in buffer-alcoholic medium. The maximum absorbance occurs at 655 nm with a molar absorptivity of 1.2104 lmol1cm1. Beer's law is obeyed

N. Vu?i?; Z. Ili?

1989-01-01

278

Simple reversed-phase HPLC method with spectrophotometric detection for measuring acetaminophen-protein adducts in rat liver samples.  

PubMed

A simple reversed-phase HPLC method for measuring hepatic levels of acetaminophen- (APAP-) protein adduct following an overdose of APAP was developed. An aliquot of liver homogenate in phosphate-buffered saline pH 7.4 (PBS) was placed on a Nanosep centrifugal device, which was centrifuged to obtain a protein residue. This residue was incubated with a solution of p-aminobenzoic acid (PABA), the internal standard, and bacterial protease in PBS, transferred to a Nanosep centrifugal device, and centrifuged. A 100??L portion of the filtrate was analyzed on a YMC-Pack ODS-AMQ C18 column, using 100?mM potassium dihydrogen phosphate-methanol-acetic acid (100?:?0.6?:?0.1) as the mobile phase, a flow rate of 1?mL/min, and photometric detection at 254?nm. PABA and APAP-cystein-S-yl (APAP-Cys) eluted at ~14.7?min and 22.7?min, respectively. Method linearity, based on on-column concentrations of APAP-Cys, was observed over the range 0.078-40??g. Recoveries of APAP-Cys from spiked blank liver homogenates ranged from ~83% to 91%. Limits of detection and of quantification of APAP-Cys, based on column concentrations, were 0.06??g and 0.14??g, respectively. RSD values for interday and intraday analyses of a blank liver homogenate spiked with APAP-Cyst at three levels were, in all cases, ?1.0% and <1.5%, respectively. The proposed method was found appropriate for comparing the antidotal properties of N-acetylcysteine and taurine in a rat model of APAP poisoning. PMID:22619591

Acharya, Miteshkumar; Lau-Cam, Cesar A

2012-01-01

279

Micellar HPLC and derivative spectrophotometric methods for the simultaneous determination of fluconazole and tinidazole in pharmaceuticals and biological fluids.  

PubMed

Micellar high-performance liquid chromatography (HPLC) and first-derivative ultraviolet spectrophotometry were used to simultaneously determine fluconazole (FLZ) and tinidazole (TNZ) in combined pharmaceutical dosage forms. The derivative procedure is based on the linear relationship between the drug concentration and the first derivative amplitudes at 220 and 288 nm for FLZ and TNZ, respectively. The calibration graphs were linear in the range of 1.5-9.0 g/mL for FLZ and 10.0-60.0 g/mL for TNZ. Furthermore, an HPLC procedure with ultraviolet detection at 210 nm was developed. For the HPLC procedure, good chromatographic separation was achieved using an ODS C18 column (250 4.6 mm i.d.). The mobile phase containing 0.15M sodium dodecyl sulphate, 0.3% triethylamine and 12% n-propanol in 0.02M orthophosphoric acid at pH 5.5 was pumped at a flow rate of 1 mL/min. Indapamide was used as an internal standard. The method showed good linearity over the concentration ranges of 1.5-30.0 and 10.0-200.0 g/mL, with limits of detection of 0.36 and 2.70 g/mL and limits of quantification of 1.1 and 8.2 g/mL for FLZ and TNZ, respectively. The suggested methods were successfully applied for the simultaneous analysis of the drugs in their laboratory prepared mixture, co-formulated tablet and single dosage forms. Moreover the second method was also extended to the determination of the drugs in biological fluids. PMID:23568958

Belal, F; Sharaf El-Din, M K; Eid, M I; El-Gamal, R M

2014-04-01

280

Determination of dithiocarbamate fungicide residues in food by a spectrophotometric method using a vertical disulfide reaction system.  

PubMed

Dithiocarbamates are a class of fungicides extensively used in many crops worldwide. The current residue definition of dithiocarbamates in food for compliance with maximum residue limits, at national and international levels, is total residues arising from the use of any or each dithiocarbamate fungicide, determined as CS(2). The analytical method most frequently used to analyze dithiocarbamate residues in food for monitoring purposes was proposed more than 30 years ago. In this method, total dithiocarbamates are decomposed to CS(2), which is purified and reacted with a cupric reagent. The yellow complex formed is quantified by spectrophotometry. In this paper, a new reaction system for the purification and complexation of CS(2) is proposed. The new system is less fragile than the traditional design, is easier to assemble, and allows for a higher sample throughput, in addition to being of low cost. Recovery of added mancozeb, thiram, or ziram (0.15-8.0 mg/kg) in rice, beans, apple, banana, orange, papaya, tomato, cucumber, and potato ranged from 82 to 120%, with relative standard deviations from 0 to 10% (n = 3 or 5). Analysis of apple, tomato, and papaya samples with field-incurred dithiocarbamate residues showed comparable results using both the traditional and the new reaction systems. PMID:11599982

Caldas, E D; Conceio, M H; Miranda, M C; de Souza, L C; Lima, J F

2001-10-01

281

The variety of UV-induced pyrimidine dimeric photoproducts in DNA as shown by chromatographic quantification methods.  

PubMed

Induction of DNA damage is one of the major consequences of exposure to solar UV radiation in living organisms. UV-induced DNA photoproducts are mostly pyrimidine dimers, including cyclobutane pyrimidine dimers, pyrimidine (6-4) pyrimidone photoproducts and Dewar valence isomers. In the last few decades, a large number of methods have been developed for the quantification of these pyrimidine dimers. The present review emphasizes the contribution of chromatographic techniques to our better understanding of the basic DNA photochemistry and the better description of damage in cells. PMID:23572060

Douki, Thierry

2013-08-01

282

Simple and Selective Spectrophotometric Method for the Determination of Iron (III) and Total Iron Content, Based on the Reaction of Fe(III) with 1,2-Dihydroxy-3,4-Diketocyclo-Butene (Squaric Acid)  

Microsoft Academic Search

.?Squaric acid (1,2-dihydroxy-3,4-diketo-cyclobutene) is used in a specific reaction with Fe(III) for the spectrophotometric\\u000a determination of Fe(III) and total iron content. The optimization of the experimental parameters leads to the establishment\\u000a of a simple, fast and accurate analytical method. The analytical procedure includes mixing ammonium squarate (40?mM), prepared\\u000a in a phthalate buffer solution of pH 2.7, with the sample and

Constantine D. Stalikas; Alexandros Ch. Pappas; Miltiades I. Karayannis; Panayotis G. Veltsistas

2003-01-01

283

Determination of Cephalexin Monohydrate in Pharmaceutical Dosage Form by Stability-Indicating RP-UFLC and UV Spectroscopic Methods  

PubMed Central

An ultra-fast liquid chromatographic method and two UV spectroscopic methods were developed for the determination of cephalexin monohydrate in pharmaceutical dosage forms. Isocratic separation was performed on an Enable C18G column (250 mm 4.6 mm i.d., 5 ?m) using methanol:0.01 M TBAHS (50:50, v/v) as the mobile phase at a flow rate of 1.0 ml/min. The PDA detection wavelength was set at 254 nm. The UV spectroscopic method was performed at 261 nm and at 256266 nm for the AUC method using a phosphate buffer (pH=5.5). The linearity was observed over a concentration range of 1.0120 ?g/ml for UFLC and both of the UV spectroscopic methods (correlation coefficient=0.999). The developed methods were validated according to ICH guidelines. The relative standard deviation values for the intraday and interday precision studies were < 2%, and the accuracy was > 99% for all of the three methods. The developed methods were used successfully for the determination of cephalexin in dry syrup formulation. PMID:24482771

Panda, Sagar Suman; Ravi Kumar, Bera V. V.; Dash, Rabisankar; Mohanta, Ganeswar

2013-01-01

284

Determination of sotolon content in South African white wines by two novel HPLC-UV and UPLC-MS methods.  

PubMed

Sotolon has been reported to play an important role in the atypical ageing and aroma character of many wines. A number of analytical techniques for sotolon analysis in wine have been reported, but these often require extensive sample preparation. In this work we report a HPLC-UV method and a novel UPLC-MS method to determine sotolon concentrations in white wines with little sample preparation applied for the first time for the evaluation of sotolon levels in South African wines. The validation showed that the instrumental methods had good accuracy, repeatability and linearity, but the UPLC-MS method proved more sensitive. For both methods, quantification limits were lower than the sotolon odour threshold in wine (10?g/L), 0.86?g/L and 0.013?g/L, for HPLC-UV and UPLC-MS methods, respectively. Sotolon levels in 65 South African white wines were often found to be lower than the reported odour threshold, with the highest concentration being 9.11?g/L. However, for low levels (<1?g/L), unknown interferences in certain wines led to sotolon not being quantified with the HPLC-UV method, which made the UPLC-MS method more suitable. PMID:25236214

Gabrielli, Mario; Buica, Astrid; Fracassetti, Daniela; Stander, Marietjie; Tirelli, Antonio; du Toit, Wessel J

2015-02-15

285

A simple and rapid high-performance liquid chromatographic method for determining tobramycin in pharmaceutical formulations by direct UV detection  

PubMed Central

Background: Tobramycin, an aminoglycoside antibiotic, is a polar pharmaceutical compound which lacks a UV absorbing chromophore. Due to the absence of a UV absorbing chromophore and high polar nature of this antibiotic, the analysis of such compounds becomes a major challenge. Objective: To overcome these problems, a novel method for the determination aminoglycoside tobramycin was developed and validated based on reversed-phase high-performance liquid chromatography (RP-HPLC) with UV detector. Materials and Methods: An isocratic mobile phase consists of buffer 0.05 M diammonium hydrogen phosphate, pH adjusted to 10.0 using tetramethyl ammonium hydroxide. Chromatography was carried out at 25C on a Purosphere RP-8e, 250 mm 4.6 mm, 5mm. The detection was carried out using variable wavelength UV-Vis detector set at 210 nm. The compounds were eluted isocratically at a steady flow rate of 1.0 mL/min. Result and Discussion: Tobramycin retention time was about 9.0 min with an asymmetry factor of 1.4. A logarithmic calibration curve was obtained from 0.47 to 0.71 mg/mL (r > 0.9998). Within-day %RSD was 0.29 (n = 6, 0.60 mg/mL) and between-day %RSD was 0.54 Specificity/ selectivity experiments revealed the absence of interference from excipients, recovery from spiked samples was between 99.0100.0 percent. Conclusions: A HPLC method based on UV detection has been developed and validated for determination of tobramycin from ophthalmic solution. The method is simple, rapid, specific, accurate (error 0.80%), precise (RSD <2.0%) and linear (r2=0.9998). The described method is suitable for routine analysis and quality control of ophthalmic solution containing tobramycin. PMID:23781441

Ruckmani, K.; Shaikh, Saleem Z.; Khalil, Pavne; Muneera, M. S.

2011-01-01

286

Spectrophotometric determination of uranium in nuclear waste  

Microsoft Academic Search

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 significant interferences were observed from 34 interfering ions when a tri-n-octylphosphine oxide (TOPO) pre-extraction of U was used. The effect of pH, color development time, bromo-PADAP concentration,

Winters

1976-01-01

287

Calmagite as a spectrophotometric reagent for aluminium.  

PubMed

Calmagite is proposed as a sensitive spectrophotometric reagent for aluminium, (570mmu) = 42000. After aqueous phase reaction at pH 8.6, the metal-reagent complex is extracted into chloroform by formation of an ion-association complex with a quaternary ammonium salt. The method is free from interference by common anions, and cationic interferences may be eliminated by the use of cyanide and EDTA as masking agents. PMID:18960299

Woodward, C; Freiser, H

1968-03-01

288

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

289

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

2011-01-01

290

Spectrophotometric Quantitation of Metformin in Bulk Drug and Pharmaceutical Formulations using Multivariate Technique.  

PubMed

A sensitive and accurate UV spectrophotometric method with multivariate calibration technique for the determination of metformin hydrochloride in bulk drug and different pharmaceutical formulations has been described. This technique is based on the use of the linear regression equations by using relationship between concentration and absorbance at five different wavelength. The results were treated statistically and were found highly accurate, precise and reproducible. The method is accurate, precise (% recovery 102.50+/-0.063, CV

Arayne, M S; Sultana, Najma; Zuberi, M H; Siddiqui, F A

2009-05-01

291

UV-Visible Spectroscopic Method and Models for Assessment and Monitoring of Harmful Algal Blooms  

NASA Technical Reports Server (NTRS)

The development of an enhanced predictive and early warning capability for the occurrence and impact of harmful algal blooms (HABs) would be of great benefit to coastal communities. A critical issue for early detection and monitoring of HABs is the need to detect harmful algal species within a mixed-species phytoplankton assemblage. Possession of UV-absorbing compounds called mycosporine-like amino acids (MAAs) may be one factor that allows HAB species to out-compete their phytoplankton neighbors. Possession of MAAs, which we believe can be inferred from strong UV-absorption signals in phytoplankton absorption coefficients, can be used as a flag for potential HAB outbreak. The goal of this project was to develop a solar simulating UV-visible incubator to grow HAB dinoflagellates, to begin MAA analysis of samples collected on global cruises, and to carry out initial experiments on HAB dinoflagellate species in pure culture. Our scientific objectives are to quantify MAA production and spectral induction mechanisms in HAB species, to characterize spectral absorption of MAAs, and to define the ecological benefit of MAAs (i.e. photoprotection). Data collected on cruises to the global oceans will be used to parameterize phytoplankton absorption in the UV region, and this parameterization could be incorporated into existing models of seawater optical properties in the UV spectral region. Data collected in this project were used for graduate fellowship applications by Elizabeth Frame. She has been awarded an EPA STAR fellowship to continue the work initiated by this project.

Mitchell, B. Greg

2000-01-01

292

Stepwise injection spectrophotometric determination of epinephrine.  

PubMed

Simple, rapid and fully automated methods for the manual and automated spectrophotometric determination of epinephrine have been developed by using schemes of stepwise injection (SWIA) and sequential injection analysis (SIA) implemented in the same manifold. The determination is based on the formation of reduced form of 18-molybdodiphosphate heteropoly anion by its reaction with epinephrine. Using of the reaction vessel in the general SWIA configuration instead of a holding and reaction coil in the SIA manifold provides several essential advantages, including higher sensitivity and lower reagent consumption. The linear dependence of the analytical signal on the epinephrine concentration was preserved over the range of 1.5-30, 3.0-30, and 1.5-25?molL(-1) by using of SWIA, SIA and spectrophotometric analysis, respectively. The relative standard deviation for the SWIA determination of 10?molL(-1) epinephrine was 1.8% (n=10). PMID:22817929

Bulatov, Andrey V; Petrova, Anastasiia V; Vishnikin, Andriy B; Moskvin, Aleksey L; Moskvin, Leonid N

2012-07-15

293

A Reverse Phase HPLC-UV and HPTLC Methods for Determination of Plumbagin in Plumbago indica and Plumbago zeylanica  

PubMed Central

A reverse phase HPLC method with UV detection has been developed and validated in order to quantify plumbagin, the bioactive marker of the roots of P. indica and P. zeylanica. A quantitative HPTLC method was also developed using hexane: ethyl acetate (8:2) as the mobile phase. The plumbagin content in the roots were determined using both the methods. P. indica was found to contain significantly higher amount of plumbagin than P. zeylanica. The HPLC and HPTLC methods described here are simple, rapid, accurate and sensitive. PMID:21369461

Unnikrishnan, K. P.; Raja, S. Sudhakar; Balachandran, Indira

2008-01-01

294

Validated spectrophotometric methods for the determination of amiodarone hydrochloride in commercial dosage forms using p-chloranilic acid and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone.  

PubMed

Two simple, sensitive and economical spectrophotometric methods have been developed for the determination of amiodarone hydrochloride in pure form and commercial dosage form. These methods (A and B) are based on the reaction of amiodarone base as n-electron donor with p-chloranilic acid and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as pi-acceptors to give highly colored complex species which absorb maximally at 535 and 570 nm, respectively. Beer's law is obeyed in the concentration ranges 10.0 - 360.0 and 2.0 - 65.0 microg ml(-1) for methods A and B, respectively. Application of the proposed methods to commercial pharmaceutical tablets are presented. PMID:15352517

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

2004-08-01

295

Characteristics and performance of the Sunna high dose dosemeter using green photoluminescence and UV absorption readout methods.  

PubMed

Growth in the use of ionising radiation for medical sterilisation 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. The Sunna dosemeter can be mass-produced inexpensively with high precision. Both the photoluminescent and the UV absorption reader are simple and inexpensive. Both methods of analysis display negligible humidity effects, minimal dose rate dependence, acceptable post-irradiation effects, and permit measurements with a precision of nearly 1% 1sigma. The UV method shows negligible irradiation temperature effects from -30 degrees C to +60 degrees C. The photoluminescence method shows negligible irradiation temperature effects above room temperature for sterilisation dose levels and above. The dosimetry characteristics of these two readout methods are presented along with performance data in commercial sterilisation facilities. PMID:12382704

Miller, S D; Murphy, M K; Tinker, M R; Kovacs, A; McLaughlin, W

2002-01-01

296

UHPLC-UV method for the determination of flavonoids in dietary supplements and for evaluation of their antioxidant activities.  

PubMed

A simple and rapid ultra-high performance liquid chromatographic (UHPLC) method coupled with an ultraviolet detector (UV) has been developed and validated for the separation and determination of 14 major flavonoids (()-catechin, (-)-epicatechin, glycitin, (-)-epicatechin gallate, rutin, quercitrin, hesperidine, neohesperidine, daidzein, glycitein, quercetin, genistein, hesperetin, and biochanin A) in herbal dietary supplements. The flavonoids have been separated on a Chromolith Fast Gradient Monolithic RP-18e column utilizing a mobile phase composed of 0.05% trifluoroacetic acid in water and acetonitrile in gradient elution mode. Under these conditions, flavonoids were separated in a 5 min run. The selectivity of the developed UHPLC-UV method was confirmed by comparison with ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) analysis. The validation parameters such as linearity, sensitivity, precision, and accuracy were found to be highly satisfactory. The optimized method was applied to determination of flavonoids in different dietary supplements. Additionally, the developed HPLC-UV method combined with 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) assay was used in the evaluation of antioxidant activity of the selected flavonoids. PMID:25459947

Magiera, Sylwia; Baranowska, Irena; Lautenszleger, Anna

2015-01-01

297

An environmentally friendly (green) reversed-phase liquid chromatography method for UV filters determination in cosmetics  

Microsoft Academic Search

A green procedure based on reversed-phase liquid chromatography with gradient elution using environmentally friendly solvents, has been developed to determine 18 UV filters, which are most used in Europe nowadays as sunscreen in cosmetics. Samples were weighed and dissolved in ethanol. Two aliquots were taken from the initial sample solution to prepare two solutions, so analytes could be determined chromatographically

A. Salvador; A. Chisvert

2005-01-01

298

Spectrophotometric determination of benzene in ethanol.  

PubMed

A rapid, simple spectrophotometric method for the detection and determination of benzene in ethanol is described. Thus, using 1 cm cuvettes and applying the first and/or the second derivative methods, benzene can be determined in ethanol over the concentration range of 5-25 p.p.m. with a CV% less than 1% and with a detection limit of 2 p.p.m. This is considered to be an improvement over the method currently given in the British Pharmacopoeia. PMID:1856248

Barary, M H; Sabry, S M; Wahbi, A A

1991-04-01

299

Postharvest induction modeling method using UV irradiation pulses for obtaining resveratrol-enriched table grapes: a new "functional" fruit?  

PubMed

A modeling method for the induction of resveratrol synthesis by UV irradiation pulses in Napoleon table grapes is proposed. The method is based on the combination of four main parameters: irradiation power (IW), irradiation time (IT), irradiation distance (ID), and number of elapsed days to achieve the highest resveratrol accumulation (D(m)). Maximum resveratrol content (11-fold higher than untreated grapes) was achieved using the combination: IW = 510 W, IT = 30 s, ID = 40 cm, and D(m) = 3 days. Sensory characteristics and main features of irradiated grapes (color, weight, firmness, flavor, size, ripening index and vitamin C content) remained unaltered after 1 week of storage. UV induction signal migrated to the hidden side of the grape skin with a delay of 3 days as compared to the directly irradiated side. Phenolic compounds were not detected in Napoleon grape flesh. Resveratrol content per standard serving (200 g) of irradiated grape was about 3 mg, an amount more than 10-fold higher than that of untreated Napoleon grapes. This means that a serving of irradiated grape (unpeeled) could supply the resveratrol content equivalent to 3 glasses of a red wine with high resveratrol content ( approximately 1 mg/glass). Therefore, controlled UV irradiation pulses are useful as a simple postharvest treatment (and alternative to genetic engineering) to obtain possible "functional" grapes (with enhanced health-promoting properties) as a dietary source of high resveratrol content. PMID:11600065

Cantos, E; Espn, J C; Toms-Barbern, F A

2001-10-01

300

Simple HPLC-UV method for the quantification of metformin in human plasma with one step protein precipitation.  

PubMed

This study presents the optimization of a simple HPLC-UV method for the determination of metformin in human plasma. Ion pair separation followed by UV detection was performed on deproteinized human plasma samples. The separation was carried out on a Discovery Reversed Phase C-18 column (250נ4.6mm, 5?m) with UV detection at 233nm. The mobile phase contained 34% acetonitrile and 66% aqueous phase. Aqueous phase contained 10mM KH2PO4 and 10mM sodium lauryl sulfate. Aqueous phase pH was adjusted to 5.2. The mobile phase was run isocratically. The flow rate of the mobile phase was maintained at 1.3ml/min. The linearity of the calibration curve was obtained in the concentration range of 0.125-2.5?g/ml and coefficient of determination (R (2)) was found to be 0.9951. The lowest limit of quantification and detection was 125 and 62ng/ml respectively. No endogenous substances were found to interfere with the peaks of drug and internal standard. The intra-day and inter-day coefficient of variations was 6.97% or less for all the selected concentrations. The relative errors at all the studied concentrations were 5.60% or less. This method is time efficient and samples are easy to prepare with minimum dilution. So, it can be applied for monitoring metformin in human plasma. PMID:25473337

Chhetri, Himal Paudel; Thapa, Panna; Van Schepdael, Ann

2014-11-01

301

Simple HPLC-UV method for the quantification of metformin in human plasma with one step protein precipitation  

PubMed Central

This study presents the optimization of a simple HPLC-UV method for the determination of metformin in human plasma. Ion pair separation followed by UV detection was performed on deproteinized human plasma samples. The separation was carried out on a Discovery Reversed Phase C-18 column (250נ4.6mm, 5?m) with UV detection at 233nm. The mobile phase contained 34% acetonitrile and 66% aqueous phase. Aqueous phase contained 10mM KH2PO4 and 10mM sodium lauryl sulfate. Aqueous phase pH was adjusted to 5.2. The mobile phase was run isocratically. The flow rate of the mobile phase was maintained at 1.3ml/min. The linearity of the calibration curve was obtained in the concentration range of 0.1252.5?g/ml and coefficient of determination (R2) was found to be 0.9951. The lowest limit of quantification and detection was 125 and 62ng/ml respectively. No endogenous substances were found to interfere with the peaks of drug and internal standard. The intra-day and inter-day coefficient of variations was 6.97% or less for all the selected concentrations. The relative errors at all the studied concentrations were 5.60% or less. This method is time efficient and samples are easy to prepare with minimum dilution. So, it can be applied for monitoring metformin in human plasma. PMID:25473337

Chhetri, Himal Paudel; Thapa, Panna; Van Schepdael, Ann

2013-01-01

302

Green synthesis of silver/montmorillonite/chitosan bionanocomposites using the UV irradiation method and evaluation of antibacterial activity  

PubMed Central

In this study, silver nanoparticles (Ag-NPs) were synthesized using a green physical synthetic route into the lamellar space of montmorillonite (MMT)/chitosan (Cts) utilizing the ultraviolet (UV) irradiation reduction method in the absence of any reducing agent or heat treatment. Cts, MMT, and AgNO3 were used as the natural polymeric stabilizer, solid support, and silver precursor, respectively. The properties of Ag/MMT/Cts bionanocomposites (BNCs) were studied as the function of UV irradiation times. UV irradiation disintegrated the Ag-NPs into smaller sizes until a relatively stable size and size distribution were achieved. Meanwhile, the crystalline structure and d-spacing of the MMT interlayer, average size and size distribution, surface morphology, elemental signal peaks, functional groups, and surface plasmon resonance of Ag/MMT/Cts BNCs were determined by powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray fluorescence, Fourier transform infrared, and UV-visible spectroscopy. The antibacterial activity of Ag-NPs in MMT/Cts was investigated against Gram-positive bacteria, ie, Staphylococcus aureus and methicillin-resistant S. aureus and Gram-negative bacteria (ie, Escherichia coli) by the disk diffusion method on MullerHinton Agar at different sizes of Ag-NPs. All of the synthesized Ag/MMT/Cts BNCs were found to have high antibacterial activity. These results show that Ag/MMT/Cts BNCs can be useful in different biologic research and biomedical applications, such as surgical devices and drug delivery vehicles. PMID:21116328

Shameli, Kamyar; Ahmad, Mansor Bin; Yunus, Wan Md Zin Wan; Rustaiyan, Abdolhossein; Ibrahim, Nor Azowa; Zargar, Mohsen; Abdollahi, Yadollah

2010-01-01

303

UV-vis spectra as an alternative to the Lowry method for quantify hair damage induced by surfactants.  

PubMed

It is well known that long term use of shampoo causes damage to human hair. Although the Lowry method has been widely used to quantify hair damage, it is unsuitable to determine this in the presence of some surfactants and there is no other method proposed in literature. In this work, a different method is used to investigate and compare the hair damage induced by four types of surfactants (including three commercial-grade surfactants) and water. Hair samples were immersed in aqueous solution of surfactants under conditions that resemble a shower (38C, constant shaking). These solutions become colored with time of contact with hair and its UV-vis spectra were recorded. For comparison, the amount of extracted proteins from hair by sodium dodecyl sulfate (SDS) and by water were estimated by the Lowry method. Additionally, non-pigmented vs. pigmented hair and also sepia melanin were used to understand the washing solution color and their spectra. The results presented herein show that hair degradation is mostly caused by the extraction of proteins, cuticle fragments and melanin granules from hair fiber. It was found that the intensity of solution color varies with the charge density of the surfactants. Furthermore, the intensity of solution color can be correlated to the amount of proteins quantified by the Lowry method as well as to the degree of hair damage. UV-vis spectrum of hair washing solutions is a simple and straightforward method to quantify and compare hair damages induced by different commercial surfactants. PMID:25277290

Pires-Oliveira, Rafael; Joekes, Ins

2014-11-01

304

ANALYTICAL METHOD FOR 1METHYL4-AMINO-PIPERAZINE IN AN ACTIVE PHARMACEUTICAL INGREDIENT USING CHEMICAL DERIVATIZATION AND HPLC-UV  

Microsoft Academic Search

A method to form a UV-active derivative of 1-methyl-4-amino-piperazine (AMP) was developed. The method was based on the reaction of AMP with benzaldehyde, forming a stable derivative, which was UV-active. The method was used to analyze samples of an active pharmaceutical ingredient (API) for trace amounts of AMP. The derivatization approach allowed detection of AMP at low levels, using readily

Jyoti Patel; Eric Loeser; Rudy Kircher; Hanumantha Rao Marrepalli; Steven Fazio; Donald Drinkwater; Patrick Drumm

2010-01-01

305

[Method validation according to ISO 15189 and SH GTA 04: application for the extraction of DNA and its quantitative evaluation by a spectrophotometric assay].  

PubMed

According to the French legislation on medical biology (January 16th, 2010), all biological laboratories must be accredited according to ISO15189 for at least 50% of their activities before the end of 2016. The extraction of DNA from a sample of interest, whether solid or liquid is one of the critical steps in molecular biology and specifically in somatic or constitutional genetic. The extracted DNA must meet a number of criteria such quality and also be in sufficient concentration to allow molecular biology assays such as the detection of somatic mutations. This paper describes the validation of the extraction and purification of DNA using chromatographic column extraction and quantitative determination by spectrophotometric assay, according to ISO15189 and the accreditation technical guide in Human Health SH-GTA-04. PMID:24113450

Harl, Alexandre; Lion, Mava; Husson, Marie; Dubois, Cindy; Merlin, Jean-Louis

2013-01-01

306

Spectrophotometric evaluation of postmortem lividity.  

PubMed

Under low ambient temperatures normally bluish postmortem lividity adopts a bright red or pink colour due to resaturation of haemoglobin with O2. The most important differential diagnosis in the presence of pink hypostasis is carbon monoxide poisoning. To answer the question if objective measuring methods allow differentiation of hypostasis with regard to cold exposition or carbon monoxide poisoning, spectrophotometric measurements were performed and the colorimetric measures as well as the spectral reflectance curves of the postmortem lividity were determined. The colorimetric measures CIE-L*a*b* showed similar values for all bright red livores mortis; differentiation between CO intoxication and cold exposition was not possible. Reflectance curves of pink hypostasis after cold storage showed the typical pattern of O2-rich blood with reflectance minima at wavelengths 541 nm and 576 nm and a reflectance maximum at 560 nm. Pink hypostasis because of carbon monoxide poisoning showed a shift of the reflectance maximum toward 555 nm and a flattened curve in all cases with COHb concentrations exceeding 52%, whereas these changes were not regularly observed with lower COHb levels. PMID:10077859

Bohnert, M; Weinmann, W; Pollak, S

1999-01-11

307

SPECTROPHOTOMETRIC DETERMINATION OF URANIUM IN ORGANIC-SOLVENT SOLUTIONS  

Microsoft Academic Search

The ammonium thioglycolate method of Davenport and Thomason is used in ; the spectrophotometric determination of uranium in aqueous solutions. The ; results of application of this method to the determination of uranium in various ; organic solvents, and in tri-n-butyl phosphate, diluted with various organic ; solvents, is presented. (J.R.D.);

Z. I. Dizdar; I. D. Obrenovic

1958-01-01

308

THE SPECTROPHOTOMETRIC DETERMINATION OF URANIUM WITH XYLENOL ORANGE  

Microsoft Academic Search

A new spectrophotometric method for determining trace amounts of uranium ; was developed. This method is based on the coloration of xylenol orange with ; uranium(IV) formed by the reduction of uranium(VI) in the presence of ascorbic ; acid. The effects of the pH value, reagent, and boiling time were thoroughly ; investigated, and experimental conditions which make possible the

Makoto Otomo

1963-01-01

309

Determination of total phenols in tea infusions, tomato and apple juice by terbium sensitized fluorescence method as an alternative approach to the FolinCiocalteu spectrophotometric method  

Microsoft Academic Search

A fast screening of total phenols in tea infusions, tomato and apple juice samples using terbium sensitized fluorescence is described. The proposed method is based on the fluorescence sensitization of terbium (Tb3+) by complexation with flavonols (quercein as a reference standard) (at pH 7.0), which fluoresces intensely with an emission maximum at 545nm when excited at 310nm. Quercetin and terbium

Masoomeh Shaghaghi; Jamshid L. Manzoori; Abolghasem Jouyban

2008-01-01

310

Highly sensitive catalytic spectrophotometric determination of ruthenium.  

PubMed

A new and highly sensitive catalytic kinetic method (CKM) for the determination of ruthenium(III) has been established based on its catalytic effect on the oxidation of l-phenylalanine (l-Pheala) by KMnO(4) in highly alkaline medium. The reaction has been followed spectrophotometrically by measuring the decrease in the absorbance at 526nm. The proposed CKM is based on the fixed time procedure under optimum reaction conditions. It relies on the linear relationship where the change in the absorbance (DeltaA(t)) versus added Ru(III) amounts in the range of 0.101-2.526ngml(-1) is plotted. Under the optimum conditions, the sensitivity of the proposed method, i.e. the limit of detection corresponding to 5min is 0.08ngml(-1), and decreases with increased time of analysis. The method is featured with good accuracy and reproducibility for ruthenium(III) determination. The ruthenium(III) has also been determined in presence of several interfering and non-interfering cations, anions and polyaminocarboxylates. No foreign ions interfered in the determination ruthenium(III) up to 20-fold higher concentration of foreign ions. In addition to standard solutions analysis, this method was successfully applied for the quantitative determination of ruthenium(III) in drinking water samples. The method is highly sensitive, selective and very stable. A review of recently published catalytic spectrophotometric methods for the determination of ruthenium(III) has also been presented for comparison. PMID:17574906

Naik, Radhey M; Srivastava, Abhishek; Prasad, Surendra

2008-01-01

311

An HPLC-UV method for the simultaneous quantification of vemurafenib and erlotinib in plasma from cancer patients.  

PubMed

Vemurafenib and erlotinib are two oral kinase inhibitors approved for the treatment of metastatic melanoma and advanced non-small cell lung cancer, respectively. In contrast with erlotinib, the single published method for analysis of vemurafenib in human plasma is based on mass spectrometry. The purpose of the present study was to develop an HPLC-UV method to simultaneously quantify these two drugs in plasma. Following liquid-liquid extraction, vemurafenib, erlotinib and sorafenib (internal standard) were separated isocratically on a C8 Xterra() MS using a mobile phase of glycine buffer (pH 9.0, 100mM)/acetonitrile (45:55, v/v). Samples were eluted at a flow rate of 0.9mL/min throughout the 12-min run. Dual UV wavelength mode was used, with vemurafenib and sorafenib monitored at 249nm, and erlotinib at 331nm. The calibration was linear in the range 1.25-100mg/L and 50-4000?g/L for vemurafenib and erlotinib, respectively. Inter- and intra-day precision was less than 6.7% and 6.6% for vemurafenib and erlotinib, respectively. This analytical method was successfully applied to assess the steady state plasma exposure of these drugs in cancer patients. This accurate method can be used in routine clinical practice to monitor vemurafenib or erlotinib concentrations in plasma from cancer patients. PMID:23602929

Zhen, Yi; Thomas-Schoemann, Audrey; Sakji, Lilia; Boudou-Rouquette, Pascaline; Dupin, Nicolas; Mortier, Laurent; Vidal, Michel; Goldwasser, Francois; Blanchet, Benoit

2013-06-01

312

Combined cloud point-solid phase extraction by dispersion of TiO? nanoparticles in micellar media followed by semi-microvolume UV-vis spectrophotometric detection of zinc.  

PubMed

A new approach is presented in this paper by using dispersed TiO2 nanoparticles (TiO2-NPs) in a combined cloud point and solid phase extraction for the efficient preconcentration and determination of Zn(2+) in various samples. In this method Zn(2+) ions are adsorbed on TiO2-NPs and transferred into surfactant rich phase. Subsequently the Zn(2+) ions are desorbed from TiO2-NPs by a dithizone solution via forming a color complex which could be detected colorimetrically. The influence of chemical variables such as pH of the sample solution, electrolyte, amount of TiO2-NPs, type and volume of the eluent on the extraction system was studied. The calibration graph was linear in the range of 0.5-90.0 g L(-1) of Zn(2+) (r=0.9996). An enrichment factor of 80 was achieved and the limit of detection for Zn(2+) was 0.33 g L(-1). The relative standard deviation (RSD) for eight replicate measurements of 10 g L(-1) and 60 g L(-1) of Zn(2+) was 1.8% and 1.5% respectively. The proposed method was successfully applied to the quantitative determination of Zn(2+) in tap water, powder milk and Zinc sulfate tablet with satisfactory results. PMID:25059144

Pourreza, Nahid; Naghdi, Tina

2014-10-01

313

Characteristics of photoconductive UV photodetector based on ZnO nanorods grown on polyethylene naphthalate substrate by chemical bath deposition method  

NASA Astrophysics Data System (ADS)

Vertically aligned ZnO nanorods were synthesized on a polyethylene naphthalate (PEN) substrate using a chemical bath deposition method at a low temperature. The structural and optical investigations revealed the high quality of the fabricated ZnO nanorods on flexible substrate. A metal-semiconductor-metal UV photodetector based on ZnO nanorods was fabricated on the PEN substrate. The optoelectronic characteristics of fabricated UV photodetector were studied in the dark and under 325 nm UV light illumination at -3 V and 3 V bias voltages. The responsivity and photosensitivity of the ZnO nanorod UV photodetector were 2.856 A/W and 1175% at 3 V bias voltage, respectively. Moreover, the response and the recovery times measured during the turn-on and turnoff of UV illumination were 1.2 s and 1.8 s, respectively.

Shabannia, R.; Hassan, H. Abu

2014-07-01

314

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 (580 nm) 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; stergaard, Jesper; Jensen, Sabrine Smedegaard; Aaltonen, Jaakko; Rantanen, Jukka; Hirvonen, Jouni; Peltonen, Leena

2013-11-20

315

A Microscale Spectrophotometric Determination of Water Hardness  

NASA Astrophysics Data System (ADS)

A spectrophotometric titration was performed to determine water hardness. The titration incorporated the traditional titration method employing EDTA as the titrant and calmagite as the indicator. The microscale experiment was carried out in a spectrometer cuvette and made use of a Texas Instruments (TI-83) calculator interfaced through a TI Calculator-Based Laboratory system to a Vernier colorimeter as the detector. Monitoring at 635 nm, one of the colorimeter's fixed wavelengths, was well suited for this analysis. Agreement was found with results from traditional titrations.

Gordon, James S.

2001-08-01

316

Effects of UV assistance on the properties of al-doped ZnO thin films deposited by sol-gel method  

NASA Astrophysics Data System (ADS)

We report here the preparation of aluminum doped zinc oxide transparent conductive thin films by a UV-assisted sol-gel method. It was found that UV irradiation creates ozone, which promotes the conductivity and transparency of the films. Boro-silicate glasses are used as substrates; an PGME is used as a solvent; after spin-coating, the films are dried and radiated with UV and then heated to 400C for decarburization and 500C for annealing under air. The surface morphologies of the prepared films are observed by FE-SEM and AFM. It was found that the films irradiated with UV-C are smoother and denser. An XRD analysis shows that the films have a typical wurtzite crystalline structure with a c-axis orientation normal to the surface. The electric resistance values measured with a four-point probe show that the films irradiated with UV have better conductivity (at approximately 3.4 10-3?-cm) than the films that did not undergo UV irradiation. An analysis by visible light spectrometry indicates that the AZO films irradiated with UV are more transparent than the films without UV-irradiation.

Tseng, Yung-Kuan; Pai, Feng-Ming; Chen, Yan-Cheng; Wu, Chao-Hsien

2013-11-01

317

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

318

Adverse Effects of UV-B Radiation on Plants Growing at Schirmacher Oasis, East Antarctica.  

PubMed

This study aimed to assess the impacts of ultraviolet-B (UV-B) radiation over a 28-day period on the levels of pigments of Umbilicaria aprina and Bryum argenteum growing in field. The depletion of stratospheric ozone is most prominent over Antarctica, which receives more UV-B radiation than most other parts of the planet. Although UV-B radiation adversely affects all flora, Antarctic plants are better equipped to survive the damaging effects of UV-B owing to defenses provided by UV-B absorbing compounds and other screening pigments. The UV-B radiations and daily average ozone values were measured by sun photometer and the photosynthetic pigments were analyzed by the standard spectrophotometric methods of exposed and unexposed selected plants. The daily average atmospheric ozone values were recorded from 5 January to 2 February 2008. The maximum daily average for ozone (310.7 Dobson Units (DU)) was recorded on 10 January 2008. On that day, average UV-B spectral irradiances were 0.016, 0.071, and 0.186 W m(-2) at wavelengths of 305, 312, and 320 nm, respectively. The minimum daily average ozone value (278.6 DU) was recorded on 31 January 2008. On that day, average UV-B spectral irradiances were 0.018, 0.085, and 0.210 W m(-2) at wavelengths of 305, 312, and 320 nm, respectively. Our results concludes that following prolonged UV-B exposure, total chlorophyll levels decreased gradually in both species, whereas levels of UV-B absorbing compounds, phenolics, and carotenoids gradually increased. PMID:24748743

Singh, Jaswant; Singh, Rudra P

2014-01-01

319

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

320

Novel spectrophotometric determination of flumethasone pivalate and clioquinol in their binary mixture and pharmaceutical formulation  

NASA Astrophysics Data System (ADS)

This work is concerned with development and validation of three simple, specific, accurate and precise spectrophotometric methods for determination of flumethasone pivalate (FP) and clioquinol (CL) in their binary mixture and ear drops. Method A is a ratio subtraction spectrophotometric one (RSM). Method B is a ratio difference spectrophotometric one (RDSM), while method C is a mean center spectrophotometric one (MCR). The calibration curves are linear over the concentration range of 3-45 ?g/mL for FP, and 2-25 ?g/mL for CL. The specificity of the developed methods was assessed by analyzing different laboratory prepared mixtures of the FP and CL. The three methods were validated as per ICH guidelines; accuracy, precision and repeatability are found to be within the acceptable limits.

Abdel-Aleem, Eglal A.; Hegazy, Maha A.; Sayed, Nour W.; Abdelkawy, M.; Abdelfatah, Rehab M.

2015-02-01

321

Spectrophotometric determination of uranium(VI) with 3-thianaphthenoyltrifluoroacetone  

Microsoft Academic Search

Summary Two visible spectrophotometric methods are described for the determination of uranium(VI) with 3-thianaphthenoyltrifluoroacetone at aph of 6.0. The effect due toph, time, solvents, reagent concentration and diverse ions are reported. Beer's law is obeyed in both cases and the molar extinction coefficients at 408 and 446 nm are 1.7104 and 2.3103 respectively.

J. R. Johnston; W. J. Holland; J. Gerard

1971-01-01

322

Estimation of scattering error in spectrophotometric measurements of light absorption  

E-print Network

Estimation of scattering error in spectrophotometric measurements of light absorption by aquatic scattering error in measurements of light absorption by aquatic particles with a typical laboratory double function of particles. We applied this method to absorption mea- surements made on marine phytoplankton

Stramski, Dariusz

323

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

324

Development of a non-thermal accelerated pulsed UV photolysis assisted digestion method for fresh and dried food samples  

NASA Astrophysics Data System (ADS)

A simple, fast digestion procedure for fresh and dried foods, using high-power pulsed UV photolysis in the presence of hydrogen peroxide, is being developed. The homogenized food samples were mixed with H 2O 2 or with a mixture of H 2O 2 and HNO 3, and irradiated for short times with a 248-nm UV excimer laser. After centrifugation, a clear, colorless solution was obtained and aliquots were deposited on Teflon filters for XRF and/or PIXE analyses. Standard reference materials (NIST Peach Leaves; Typical Diet) were also analyzed to compare recoveries and detection limits. Improvements in detection limits were observed, but a few trace elements (<1 ppm) were not reproducibly detected (Fe, Sr). This method proved to be practical for the accelerated digestion of food samples and preparing analytes in short-time intervals. In combination with PIXE and XRF, it allows high-sensitivity multi-elemental analyses for screening the nutritional elements and for food safety purposes regarding the potential presence of toxic elements. Further development to optimize and validate this procedure for a broader range of analytes is in progress.

Sols, C.; Lagunas-Solar, M. C.; Perley, B. P.; Pia, C.; Aguilar, L. F.; Flocchini, R. G.

2002-04-01

325

Determination of homocysteine thiolactone in urine by field amplified sample injection and sweeping MEKC method with UV detection.  

PubMed

Homocysteine thiolactone (Hcy-thiolactone), an intramolecular thioester, easily acylates free-amino groups in proteins, which impairs or alters the protein's biological function. Here, we describe new capillary electrophoresis assay for the determination of Hcy-thiolactone in human urine based on a field amplified sample injection and sweeping MEKC with UV detection. The two steps procedure relies on sample liquid-liquid extraction followed by CE separation and UV detection at 240nm. The Hcy-thiolactone standard added to the urine before the extraction step shows that the response of the detector is linear within the range studied, from 0.1 to 1?molL(-1) urine. The intra- and interday precision and recovery were 3.2-14.4% (average 5.1% and 9.3%) and 92.5-112.6% (average 99.8% and 99.1%), respectively. The lower limit of quantification was 0.09nmol Hcy-thiolactone in 1mL of urine. The proposed method was applied for the analysis of 15 urine samples donated by apparently healthy volunteers. The average concentration of the analyte was 0.1700.029?molL(-1). PMID:24858263

Furmaniak, Paulina; Kubalczyk, Pawe?; G?owacki, Rafa?

2014-06-15

326

Direct spectrophotometric measurement of angiotensin I-converting enzyme inhibitory activity for screening bioactive peptides  

Microsoft Academic Search

A direct, extraction-free spectrophotometric assay was developed for determination of angiotensin I-converting enzyme activity (ACE) in the presence of ACE inhibitors using hippuryl-l-histidyl-l-leucine (HHL) as the ACE-specific substrate. This method relies on previously published spectrophotometric determination of hippuric acid (HA) content in the urine, the method of which was based on the specific colorimetric reaction of HA with benzene sulfonyl

Guan-Hong Li; Huan Liu; Yong-Hui Shi; Guo-Wei Le

2005-01-01

327

Spectrophotometric determination of 6-aminopenicillanic acid using bromophenol blue and bromothymol blue  

Microsoft Academic Search

Two simple, selective and sensitive spectrophotometric methods are described for the determination of 6-aminopenicillanic acid (6-APA). The methods are based on the reaction of 6-APA with either bromophenol blue (BPB) or bromothymol blue (BTB), to give orange-red and green species, respectively. The coloured products are quantified spectrophotometrically at 625 and 616 nm for BPB and BTB, respectively. The optimization of

Alaa S. Amin; Yousry M. Issa

1995-01-01

328

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

329

Comparative study of methods for measuring window film UV and luminous transmittance  

NASA Astrophysics Data System (ADS)

This work presents a comparison of window film ultraviolet transmission calculated according ISO 13837 methods A and B and window film luminous transmission calculated for illuminates A and D65. The results show a difference from 350% to 800% in ultraviolet transmission between ISO 13837 methods A and B for the evaluated window films. On the other hand, the difference in luminous transmission results for the evaluated window films is less than 1%.

Caly, Jos P.; Ferreira, Antonio F. G., Jr.

2015-01-01

330

Validation of HPLC-UV method for determination of minor glycosides contained in Stevia rebaudiana Bertoni leaves.  

PubMed

Leaves of Stevia rebaudiana contain glycosides with sweetness and biological activity. However besides the major glycosides, there are other glycosides within extracts that may contribute to its activity, and therefore it is important to quantify them. In this work, an isocratic HPLC method was validated for determination of dulcoside A, steviolbioside, rebaudioside C and rebaudioside B. An HPLC method was performed using a C18 column (250??4.6?mm, particle size 5?m) and a UV detector set at 210?nm. The mobile phase consisted of a 32:68 (v/v) mixture of acetonitrile and sodium phosphate buffer (10?mmol/L, pH?2.6), set to a flow rate of 1.0?mL/min. The calculated parameters were: sensitivity, linearity, limit of detection (LOD), limit of quantification (LOQ), accuracy and precision. The calibration curves were linear over the working range 25-150?g/mL, with coefficient of correlation of ?0.99 and coefficient of determination of ?0.98. The LOD was 5.68-8.81?g/mL, while the LOQ was 17.21-26.69?g/mL. The percentage recoveries of fortified samples were 100??10% and precision, relative standard deviation, was <10%. The method validation showed accuracy, linearity and precision; therefore this method can be applied for quantitative analysis of minor steviol glycosides in S. rebaudiana leaves. Copyright 2014 John Wiley & Sons, Ltd. PMID:25296637

Aranda-Gonzlez, Irma; Moguel-Ordoez, Yolanda; Betancur-Ancona, David

2014-10-01

331

Quantitative determination of triperpene saponins and alkenated-phenolics from Labisia pumila using LC-UV/ELSD method and confirmation by LC-ESI-TOF  

Technology Transfer Automated Retrieval System (TEKTRAN)

This study describes the first analytical method for the determination of saponins and alkenated-phenolics from the leaves, leaves/stems and roots of Labisia pumila using a HPLC-UV-ELSD method. The separation was achieved using a reversed phase column, PDA and ELS detection, and a water/acetonitrile...

332

A LC/UV/Vis method for determination of cyanocobalamin in multivitamin dietary supplements with on-line sample clean-up  

Technology Transfer Automated Retrieval System (TEKTRAN)

A HPLC-UV method using a two-column strategy with a switching valve for on-line sample clean-up was developed for the determination of cyanocobalamin (CN-CBL-vitamin B12, in dietary supplements. The method uses two columns, an Agilent Zorbax C8 (150 mm x 4.6 mm, 5 um particle) reversed-phase column...

333

Derivative spectrophotometric determination of nitrate in plant tissue.  

PubMed

A derivative spectrophotometric method was developed to determine NO3(-)-N in plant tissues. The method is based on measurement of the first-derivative spectrum of nitrosalicylic acid in basic solution. The nitrosalicylic acid was obtained by reaction of samples with salicylic acid in concentrated sulfuric acid and was used by Cataldo et al. in nonderivative spectrophotometry. The main strength of this technique is the lack of matrix background interference, typical of plant extracts in traditional spectrophotometric methods. This method is fast, inexpensive, easy-to-apply, and highly selective. The calibration graph was linear in the range of 0.1 and 1.0 mg/L N as NO3(-). Average recovery in real matrixes (lettuce and spinach) was 102.6%; average standard deviation was 3.3. This method has been applied to leaves of 4 types of lettuce. PMID:14979689

Lastra, Olga C

2003-01-01

334

Spectrophotometric Determination of Certain Benzimidazole Proton Pump Inhibitors  

PubMed Central

Spectrophotometric method for the determination of certain proton pump inhibitors belonging to the benzimidazole class of compounds has been developed. The method is based on the reaction of omeprazole, lansoprazole, pantoprazole, rabeprazole and esomeprazole with iron (III) and subsequent reaction with ferricyanide under neutral condition which yields Prussian blue product with maximum absorption at 720730 nm. The commonly encountered excipients and additives that often accompany pharmaceutical preparations did not interfere with the determination. The method was applied for the determination of omeprazole, lansoprazole, pantoprazole, rabeprazole and esomeprazole in pharmaceutical preparations and no difference was found statistically. Thus, the spectrophotometric method can be applied as inexpensive, rapid, easy, accurate and precise method for the routine analysis of the five proton pump inhibitors in pharmaceutical preparations. PMID:20046782

Syed, A. A.; Syeda, Ayesha

2008-01-01

335

DEVELOP NEW TOTAL ORGANIC CARBON/SPECIFIC UV ABSORBANCE METHOD WITH EXPANDED QUALITY CONTROL  

EPA Science Inventory

The purpose of this project is to provide a total organic carbon (TOC)/specific ultraviolet absorbance (SUVA) method that will be used by the Office of Ground Water and Drinking Water (OGWDW) to support monitoring requirements of the Stage 2 Disinfectant/Disinfection By-products ...

336

Water-soluble organic nitrogen in atmospheric aerosol: a comparison of UV and persulfate oxidation methods  

Microsoft Academic Search

Two well established methods that are widely applied in the determination of marine dissolved organic nitrogen (DON) have been investigated in their application to the determination of rainwater DON and the water-soluble organic nitrogen component of atmospheric aerosol. Empirical observation highlighted some difficulties in the analysis of DON in these non-marine matrices, so some practical suggestions for the extension of

S. E Cornell; T. D Jickells

1999-01-01

337

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 Almera, TNG in La Palma, NTT in La Silla, San Pedro Mrtir in Mxico, 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.; Mongui, M.; Masana, E.; Bellazzini, M.; Cacciari, C.; Bragaglia, A.; Weiler, M.; Bragaglia, A.

2013-05-01

338

Determination of Ciprofloxacin in Pharmaceutical Formulations Using HPLC Method with UV Detection.  

PubMed

A simple, specific, accurate and rapid reversed phase high performance liquid chromatographic method was validated for the determination of the content of ciprofloxacin in three pharmaceuticals forms: generic, similar and compounded. The results of the validation showed that the method was highly efficient for quantification of ciprofloxacin in the matrices evaluated. The recovery rates were between 97.4 to 104.3 %, and the relative standard deviations were lower than 5 % for repeatability, and lower than 5.15 % for intermediate precision. The limits of detection, quantification and practical, were 0.11, 0.35 and 1.56 ?g/ml, respectively. All compounded samples were approved with in the quality control; however, one generic and one similar sample presented above allowed level. PMID:25593388

Scherer, R; Pereira, Jessica; Firme, Juliete; Lemos, Mariana; Lemos, Mayara

2014-01-01

339

Determination of Ciprofloxacin in Pharmaceutical Formulations Using HPLC Method with UV Detection  

PubMed Central

A simple, specific, accurate and rapid reversed phase high performance liquid chromatographic method was validated for the determination of the content of ciprofloxacin in three pharmaceuticals forms: generic, similar and compounded. The results of the validation showed that the method was highly efficient for quantification of ciprofloxacin in the matrices evaluated. The recovery rates were between 97.4 to 104.3 %, and the relative standard deviations were lower than 5 % for repeatability, and lower than 5.15 % for intermediate precision. The limits of detection, quantification and practical, were 0.11, 0.35 and 1.56 ?g/ml, respectively. All compounded samples were approved with in the quality control; however, one generic and one similar sample presented above allowed level.

Scherer, R.; Pereira, Jessica; Firme, Juliete; Lemos, Mariana; Lemos, Mayara

2014-01-01

340

Spectrophotometric determination of dimenhydrinate with Reinecke salt.  

PubMed

A convenient spectrophotometric method was developed for the determination of dimenhydrinate in bulk drug and dosage forms and in 1:1 combinations with aspirin, acetaminophen, meprobamate, phenylephrine, and tolbutamide. The method consisted of reacting dimenhydrinate with reinecke salt in an acidic medium at 27 +/- 2 degrees. The purple precipitate was filtered and dissolved in acetone, and the maximum color absorption attained in 15 min was measured at 540 nm. Evidence is provided to establish the optimal experimental parameters. The stoichiometric balance of the precipitate was determined. Reasonably ideal adherence of the color absorption pattern to the Beer-Lambert law permitted microdetermination of dimenhydrinate in pure form, commercial formulations, laboratory-made combinations, and recovery experiments with good accuracy and repeatability. No interference was observed with any of the drugs or tablet adjuvants. PMID:7252821

Kar, A; Aniuha, G I

1981-06-01

341

Rapid Method for the Determination of 5-Hydroxymethylfurfural and Levulinic Acid Using a Double-Wavelength UV Spectroscopy  

PubMed Central

This study reports on a rapid method for the determination of levulinic acid (LA) and 5-hydroxymethylfurfural (HMF) in acid hydrolyze system of glucose based on UV spectroscopy. It was found that HMF and LA have a maximum absorption at the wavelengths of 284?nm and 266?nm, respectively, in a water medium, and the absorptions of HMF and LA at 284?nm and 266?nm follow Beer's law very well. However, it was found that a major spectral interference species will arise in the quantification of HMF and LA; nonetheless, this interference can be eliminated through the absorption treatment of charcoal. Therefore, both HMF and LA can be quantified with a double-wavelength technique. The repeatability of the method had a relative standard deviation of less than 4.47% for HMF and 2.25% for LA; the limit of quantification (LOQ) was 0.017?mmol/L for HMF and 4.68?mmol/L for LA, and the recovery ranged from 88% to 116% for HMF and from 94% to 105% for LA. The present method is simple, rapid, and accurate. It is suitable to use in the research of the preparation of HMF and LA in biorefinery area. PMID:24228006

Xue, Guoxin

2013-01-01

342

Development and validation of RP-HPLC-UV method for the determination ofGlipizide in human plasma.  

PubMed

A simple, sensitive and selective HPLC method with UV detection for determination of Glipizide in human plasma was developed. Liquid-liquid extraction method was used to extract the drug from the plasma samples. Chromatographic separation of Glipizide was achieved using C18 column (ZORBAX ODS 4.6נ150mm). The mobile phase was comprised of 0.01M potassium dihydrogen phosphate and acetonitrile (65:35, v/v) adjusted to pH 4.25 with glacial acetic acid. The analysis was run at a flow rate of 1.5mL/min with an injection volume was 20?L. The detector was operated at 275nm. The calibration curve was linear over a concentration range of 50-1600ng/mL. Intra-day and inter-day precision and accuracy values were below 15%. The limit of quantification was 50ng/mL and the mean recovery was above 98%. Freeze-thaw, short-term, long-term and post-preparative stability studies showed that Glipizide in plasma sample was stable. The method may be successfully applied to analyze the Glipizide concentration in plasma samples for bioavailability and bioequivalence studies. PMID:24023449

Atif, M; Khalid, S H; Onn Kit, G L; Sulaiman, S A S; Asif, M; Chandersekaran, A

2013-03-01

343

Development and validation of RP-HPLC-UV method for the determination ofGlipizide in human plasma  

PubMed Central

A simple, sensitive and selective HPLC method with UV detection for determination of Glipizide in human plasma was developed. Liquidliquid extraction method was used to extract the drug from the plasma samples. Chromatographic separation of Glipizide was achieved using C18 column (ZORBAX ODS 4.6נ150mm). The mobile phase was comprised of 0.01M potassium dihydrogen phosphate and acetonitrile (65:35, v/v) adjusted to pH 4.25 with glacial acetic acid. The analysis was run at a flow rate of 1.5mL/min with an injection volume was 20?L. The detector was operated at 275nm. The calibration curve was linear over a concentration range of 501600ng/mL. Intra-day and inter-day precision and accuracy values were below 15%. The limit of quantification was 50ng/mL and the mean recovery was above 98%. Freeze-thaw, short-term, long-term and post-preparative stability studies showed that Glipizide in plasma sample was stable. The method may be successfully applied to analyze the Glipizide concentration in plasma samples for bioavailability and bioequivalence studies. PMID:24023449

Atif, M.; Khalid, S.H.; Onn Kit, G.L.; Sulaiman, S.A.S.; Asif, M.; Chandersekaran, A.

2013-01-01

344

Screening method for the detection of artificial colours in saffron using derivative UV-Vis spectrometry after precipitation of crocetin.  

PubMed

A screening method for the detection of artificial colours (naphthol yellow, tartrazine, quinoline yellow, Sunset yellow, Allura red, amaranth, azorubine, Ponceau 4R and Red 2G) in saffron is described. The method involves removal of crocins by precipitation of crocetin (pH 0.1, 90 degrees C) before adsorption of the artificial colours on polyamide SPE cartridges (pH 2). After washing with methanol, acetone and methanol, elution was done with a methanol:ammonia solution (95:5 v/v), and detection was performed by derivative spectrometry. Sample pretreatment changes the UV-Vis saffron extract profile in such a way that second derivative spectra can be used to identify the presence of added colours. Erythrosine, which was found to be pH dependent, could not be detected under the above conditions. The lowest detectable amount for each colour was strongly dependent on chemical structure. The recovery of carminic acid was very low possibly due to irreversible retention on the polyamide. This procedure can replace the current ISO TLC method (2003) and be used alternatively or in combination with HPLC procedures adopted in the same standard. PMID:16019836

Zalacain, A; Ordoudi, S A; Blzquez, I; Daz-Plaza, E M; Carmona, M; Tsimidou, M Z; Alonso, G L

2005-07-01

345

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 Mge; Ertrk, Sidika

2006-01-01

346

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

347

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. PMID:21333024

2011-01-01

348

An interlaboratory study on the suitability of a gradient LC-UV method as a compendial method for the determination of erythromycin and its related substances.  

PubMed

A liquid chromatographic (LC) method for the analysis of erythromycin and related substances has been adapted from an isocratic method developed by Chepkwony et al. (2001). The suitability of the method for general application as a compendial (pharmacopoeia) method has been assessed by means of an interlaboratory (collaborative) study. The method involves LC separation on a XTerra C18 column kept at 65 degrees C and UV detection at 210 nm. Five laboratories, located in Europe and the United States (US), participated in the study. Four erythromycin samples were tested. The main components (erythromycin A (EA), erythromycin B (EB), erythromycin C (EC)) and the impurities were determined. The analysis of variance was carried out on the results of the five laboratories to evaluate the between-laboratory consistencies and the laboratory-sample interaction. The estimates for the repeatability and reproducibility of the method, expressed as relative standard deviation (RSD) of the result of the determination of EA, were calculated to be 0.8% and 1.4% respectively. It is concluded that the method examined is a good replacement for the methods currently described in the European Pharmacopoeia (Ph. Eur.) and the United States Pharmacopoeia (USP), especially for its enhanced selectivity. PMID:20381987

Van den Bossche, L; Lodi, A; Schaar, J; Shaakov, S; Zorzan, M; Tranquillini, M E; Overballe-Petersen, C; Hoogmartens, J; Adams, E

2010-09-21

349

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, Hctor C.; Fernndez Band, Beatriz S.

2013-04-01

350

Separation via flotation, spectrophotometric speciation, and determination of vanadium(IV) in wastes of power stations.  

PubMed

1-(2-Hydroxy-4-methoxybenzophenone)-4-phenylthiosemicarbazone (HMBPT) was investigated as a new reagent for the flotation of vanadium(IV). At pH approximately 1.5, vanadium(IV) forms a 1:1 pale-violet complex with HMBPT in aqueous solution. An intense clear violet layer was formed after flotation, by adding an oleic acid (HOL) surfactant. The composition of the float was 1:1 [V(IV)]:[HMBPT]. A highly selective and sensitive spectrophotometric procedure was proposed for the determination of microamounts of V(IV) as its floated complex. The molar absorptivities of the V(IV)-HMBPT and V(IV)-HMBPT-HOL systems were 0.4 x 10(4) and 0.12 x 10(5) L mol(-1) cm(-1) at 560 nm, respectively. The formation constants of the species formed in the presence and absence of HOL were 4.6 x 10(7) and 8.7 x 10(5) L mol(-1), respectively. Beer's law was obeyed up to 1 x 10(-4) mol L(-1) in the aqueous layer as well as in the oleic acid layer. The HMBPT-V(IV) complexes formed in the aqueous solution and scum layer were characterized by elemental analysis, infrared and UV spectrophotometric studies. The mode of chelation between V(IV) and HMBPT is proposed to be due to a reaction between the protonated bidentate HMBPT ligand and V(IV) through the S=C and N=C groups. Interferences from various foreign ions were avoided by adding excess HMBPT and/or Na2S2O3 as a masking agent. The proposed flotation method was successfully applied to the analysis of V(IV) in synthetic mixtures, wastes of power stations, simulated samples and in real ores. The separation mechanism is discussed. PMID:16317901

Akl, Magda Ali; El-Asmy, Ahmed A; Yossef, Wafaa M

2005-11-01

351

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

352

Spectrophotometric determination of zinc bis-ethylenedithiocarbamate (zineb).  

PubMed

A spectrophotometric method has been developed for the determination of zineb by converting it into a molybdenum ethylenedithiocarbamate complex, which is then extracted into isobutyl methyl ketone and measured at 670 nm against a reagent blank. Beer's law is obeyed over the zineb concentration range 2-40 mug/ml in the extract. The method is sensitive and can be used for determination of zineb in the presence of ziram, thiram or ferbam. PMID:18964859

Rao, A L; Verma, N

1989-10-01

353

Quantitative spectrophotometric determination of alkaloids in roots of Vinca herbacea  

Microsoft Academic Search

A new spectrophotometric method has been developed for the quantitative determination of pharmacologically active alkaloids\\u000a (maydine, reserpinine, kopsinine, tabersonine, norfluorocurarine) and their sum in roots of Vinca herbacea Walds. et Kit. The proposed technique is highly reproducible and adequately reflects the content of alkaloids in the roots\\u000a and preparations of Vinca herbacea, which allows this method to be used for

V. Yu. Vachnadze; E. Z. Dzhakeli; I. A. Dadeshidze; L. G. Kintsurashvili

2010-01-01

354

Study of Methods for Producing a Tunable UV Laser for Spectroscopy at 243nm.  

NASA Astrophysics Data System (ADS)

We are beginning an experiment to precisely measure the 1S to 2S interval in atomic tritium. A narrow bandwidth tunable source of several mW at 243nm is required. We seek methods that are less expensive and cumbersome than traditional dye or Ti Sapphire lasers. An all solid state approach has been demonstrated [Zimmermann, Vuletic, Hemmerich and Hansch, Appl. Phys. Lett. 66 p2318, 1995] using a MOPA semiconductor laser with two resonant doubling cavities using KNbO3 and BBO. We study this approach but with possible improvements using PPLN as an alternative to KNbO3 and using CLBO for doubling 486nm as an alternative to BBO. Other IR laser sources are also considered. The current status of our investigations will be presented

Khademian, Ali; Shiner, David

2002-05-01

355

Kinetic Spectrophotometric Determination of Oxalic Acid Based on the Catalytic Oxidation of Bromophenol Blue by Dichromate  

Microsoft Academic Search

.?A sensitive catalytic method is developed for the spectrophotometric determination of oxalic acid. It is based on the catalytic\\u000a action of oxalic acid on a new indicator reaction the oxidation of Bromophenol Blue by dichromate in dilute sulfuric acid\\u000a medium. The reaction rate is monitored spectrophotometrically by measuring the absorbance at 600?nm after quenching the reaction\\u000a with sodium hydroxide.

Xiao-Qin Xu; Zhi-Qi Zhang

2000-01-01

356

Enantioselective HPLC-UV method for determination of eslicarbazepine acetate (BIA 2-093) and its metabolites in human plasma.  

PubMed

Eslicarbazepine acetate (BIA 2-093) is a novel central nervous system drug undergoing clinical phase III trials for epilepsy and phase II trials for bipolar disorder. A simple and reliable chiral reversed-phase HPLC-UV method was developed and validated for the simultaneous determination of eslicarbazepine acetate, oxcarbazepine, S-licarbazepine and R-licarbazepine in human plasma. The analytes and internal standard were extracted from plasma by a solid-phase extraction using Waters Oasis HLB cartridges. Chromatographic separation was achieved by isocratic elution with water-methanol (88:12, v/v), at a flow rate of 0.7 mL/min, on a LichroCART 250-4 ChiraDex (beta-cyclodextrin, 5 microm) column at 30 degrees C. All compounds were detected at 225 nm. Calibration curves were linear over the range 0.4-8 microg/mL for eslicarbazepine acetate and oxcarbazepine, and 0.4-80 microg/mL for each licarbazepine enantiomer. The overall intra- and interday precision and accuracy did not exceed 15%. Mean relative recoveries varied from 94.00 to 102.23% and the limit of quantification of the assay was 0.4 microg/mL for all compounds. This method seems to be a useful tool for clinical research and therapeutic drug monitoring of eslicarbazepine acetate and its metabolites S-licarbazepine, R-licarbazepine and oxcarbazepine. PMID:17594694

Alves, Gilberto; Figueiredo, Isabel; Castel-Branco, Margarida; Loureiro, Ana; Fortuna, Ana; Falco, Amlcar; Caramona, Margarida

2007-11-01

357

A NEW METHOD FOR CLASSIFYING FLARES OF UV Ceti TYPE STARS: DIFFERENCES BETWEEN SLOW AND FAST FLARES  

SciTech Connect

In this study, a new method is presented to classify flares derived from the photoelectric photometry of UV Ceti type stars. This method is based on statistical analyses using an independent samples t-test. The data used in analyses were obtained from four flare stars observed between 2004 and 2007. The total number of flares obtained in the observations of AD Leo, EV Lac, EQ Peg, and V1054 Oph is 321 in the standard Johnson U band. As a result flares can be separated into two types, slow and fast, depending on the ratio of flare decay time to flare rise time. The ratio is below 3.5 for all slow flares, while it is above 3.5 for all fast flares. Also, according to the independent samples t-test, there is a difference of about 157 s between equivalent durations of slow and fast flares. In addition, there are significant differences between amplitudes and rise times of slow and fast flares.

Dal, H. A.; Evren, S., E-mail: ali.dal@ege.edu.t [Department of Astronomy and Space Sciences, University of Ege, Bornova, 35100 Izmir (Turkey)

2010-08-15

358

Kinetic spectrophotometric determination of nizatidine and ranitidine in pharmaceutical preparations.  

PubMed

A new simple and sensitive kinetic spectrophotometric method is described for analysis of nizatidine (I) and ranitidine (II). The method involves the reaction of the drugs with alkaline potassium permanganate, whereby a green color peaking at 610 nm is produced. The reaction is monitored spectrophotometrically by measuring the rate of change of absorbance of the resulting manganate species at 610 nm. Calibration graphs are linear over the concentration range 0.8-4.0 microg/ml and the precision (% RSD 1.80, 1.53 for I and II, respectively) is quite acceptable. The method is satisfactorily applied for direct analysis of pharmaceutical preparations containing I and II. A proposal of the reaction pathway is postulated. PMID:11682208

Hassan, E M; Belal, F

2002-01-01

359

Schrdinger method as N-body double and UV completion of dust  

NASA Astrophysics Data System (ADS)

We investigate large-scale structure formation of collisionless dark matter in the phase space description based on the Vlasov (or collisionless Boltzmann) equation whose nonlinearity is induced solely by gravitational interaction according to the Poisson equation. Determining the time evolution of density and peculiar velocity demands solving the full Vlasov hierarchy for the moments of the phase space distribution function. In the presence of long-range interaction no consistent truncation of the hierarchy is known apart from the pressureless fluid (dust) model, which is incapable of describing virialization due to the occurrence of shell-crossing singularities and the inability to generate vorticity and higher cumulants like velocity dispersion. Our goal is to find a simple ansatz for the phase space distribution function that approximates the full Vlasov distribution function without pathologies in a controlled way and therefore can serve as theoretical N-body double and as a replacement for the dust model. We argue that the coarse-grained Wigner probability distribution obtained from a wave function fulfilling the Schrdinger-Poisson equation (SPE) is the sought-after function. We show that its evolution equation approximates the Vlasov equation and therefore also the dust fluid equations before shell crossing, but cures the shell-crossing singularities and is able to describe regions of multistreaming and virialization. This feature was already employed in cosmological simulations of large-scale structure formation by Widrow and Kaiser (1993). The coarse-grained Wigner ansatz allows us to calculate all higher moments from density and velocity analytically, thereby incorporating nonzero higher cumulants in a self-consistent manner. On this basis we are able to show that the Schrdinger method automatically closes the corresponding hierarchy such that it suffices to solve the SPE in order to directly determine density and velocity and all higher cumulants.

Uhlemann, Cora; Kopp, Michael; Haugg, Thomas

2014-07-01

360

A simple sample preparation with HPLC-UV method for estimation of tiropramide from plasma: application to bioequivalence study.  

PubMed

A simple, rapid and selective method was developed for estimation of tiropramide from human plasma. The method involves extracting the tiropramide with n-hexane using diphenhydramine hydrochloride as internal standard. Chromatographic separation was carried out on a reversed phase C(18) column using mixture of water and acetonitrile as mobile phase with UV detection set at 230 nm. The retention time of internal standard and tiropramide were 5.6+/-0.2 and 8.3+/-0.3 min, respectively. The method was validated and found to be linear in the range of 10-200 ng/ml. The co-efficient of variation for intra-day and inter-day accuracy and precision was less than 12.8%. The mean recovery was found to be 89%. An open, randomized, two-treatment, two period, single dose crossover, bioequivalence study in 12 fasting, healthy, male, volunteers was conducted. After dosing, serial blood samples were collected for the period of 12 h. Various pharmacokinetic parameters including AUC(0-t), AUC(0-infinity), C(max), T(max), T(1/2), and elimination rate constant (K(el)) were determined from plasma concentration of both formulations. Log transformed values were compared by analysis of variance (ANOVA) followed by classical 90% confidence interval for C(max), AUC(0-t) and AUC(0-infinity) and was found to be within the range. These results indicated that the analytical method was linear, precise and accurate. Test and reference formulation were found to be bioequivalent. PMID:17127027

Imran, Khan; Punnamchand, Loya; Natvarlal, Saraf Madhusudan

2007-02-19

361

UV Throughput  

NASA Astrophysics Data System (ADS)

This proposal is designed to perform a check of the UV throughput during Cycle 7 and is loosely based on the Cycle 5 and 6 UV throughput programs {6186, 6936} as well as past Lyman alpha proposals {5778 and 7018}. The Cycle 7 program is designed to verify that the spectral response curve in the UV has not changed appreciably since the Cycle 6 measurements and that the contamination effects remain essentially same. The Lyman alpha observations will provide a check for possible contamination on the pickoff mirror.

Baggett, Sylvia

1997-07-01

362

Quantitative determination of curcuminoids from the Roots of Curcuma longa, Curcuma species and dietary supplements using an UPLC-UV-MS method  

Technology Transfer Automated Retrieval System (TEKTRAN)

A simple, fast UPLC-UV-MS method was developed for the determination of curcuminoids from roots of Curcuma longa L., Curcuma species (C. zedoaria, C. phaecaulis, C. wenyujin and C. kwangsiensis) and dietary supplements claiming to contain C. longa. The total content of curcuminoids (curcumin, desmet...

363

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

2011-04-01

364

A reversed-phase ion-interaction chromatographic method for in-vitro estimation of the percutaneous absorption of water-soluble UV filters.  

PubMed

An analytical method based on ion-interaction chromatography with UV detection for simultaneous in-vitro estimation of the percutaneous absorption of the most used water-soluble UV filters in sunscreen cosmetics is proposed. These UV filters were phenylbenzimidazole sulfonic acid, disodium phenyl dibenzimidazole tetrasulfonate, benzophenone-4, and terephthalylidene dicamphor sulfonic acid. The methodology is based on applying the sunscreen containing the target UV filters to human epidermis in a diffusion cell. Analytes are determined in the receptor solution. To ensure skin integrity, screening of the cells was carried out by analytical determination of a marker. Analytical variables such as percentage ethanol, concentration of ion-pairing agent, pH of the mobile phase, and temperature were studied in order to achieve high resolution of the chromatographic peaks in the lowest possible time of analysis. The conditions selected consisted of a mobile phase composed of 35:65 (v/v) ethanol-ammonium acetate buffer solution (pH 4, containing 50 mmol L(-1) tetra-n-butylammonium bromide). The chromatographic determination was carried out with the analytical column at 50 degrees C. UV detection was carried out at the maximum absorption wavelength for each analyte. The limit of detection (3s(y/x)/b) ranged from 16 to 65 ng mL(-1), depending on the analyte. PMID:18365182

Len, Z; Balaguer, A; Chisvert, A; Salvador, A; Herrez, M; Dez, O

2008-06-01

365

HPLC-UV method for measuring nicotinamide N-methyltransferase activity in biological samples: evidence for substrate inhibition kinetics.  

PubMed

Nicotinamide N-methyltransferase (NNMT, E.C. 2.1.1.1) N-methylates nicotinamide to produce 1-methylnicotinamide. Enhanced NNMT activity is a feature of many types of cancer, and has been linked to processes such as tumour metastasis, resistance to radiotherapy and tumour drug resistance. As such, inhibition of NNMT activity is a promising therapeutic target for cancer therapy. To screen for NNMT inhibitors, there is a need for a standardised, rapid and cost-effective NNMT assay. Here, we describe a cell-free assay coupled with ion-pairing reverse-phase HPLC-UV detection of 1-methylnicotinamide which requires minimal sample manipulation, is linear over 2.5 orders of magnitude with limits of detection and quantification of 0.05 and 0.15nmol 1-methylnicotinamide/100?L injection respectively. The assay was sufficiently sensitive to measure basal hepatic 1-methylnicotinamide concentration and NNMT activity in mouse, rabbit and human liver. 1-Methylnicotinamide concentration and the NNMT kinetic parameters specific activity, Vmax and Km all demonstrated species differences. NNMT also demonstrated substrate inhibition kinetics in all three species, which again was species-specific in term of calculated Ki. This assay demonstrates improved sensitivity over other previously published methods whilst lacking many of their drawbacks such as extensive sample preparation, use of non-physiological substrates and radioisotopic labelling. PMID:23435346

Patel, Misha; Vasaya, Muhammad M; Asker, Daniel; Parsons, Richard B

2013-03-15

366

A method to infer the stellar population that dominated the UV background at the end of reionization  

E-print Network

We present an observational test of the spectrum of the ionizing background at z~5; the test is sufficiently sensitive to determine whether Pop II or Pop III stars are the dominant source of ionizing radiation. The ionizing background at z~5 may reflect the nature of the sources responsible for the final overlap phase of reionization. We find that rest-frame extreme-UV HeI absorption will be detectable in deep spectral observations of some rare z~5 quasars; the ratio of HeI to HI absorption reflects the shape of the ionizing background in the photon energy range between 13.6 and 24.6 eV. Most z~5 quasars have too much HI absorption along their line of sight for HeI absorption to be observed. However, based on current measurements of HI absorber statistics, we use Monte Carlo simulations to demonstrate that the Sloan Digital Sky Survey (SDSS) will discover a sufficient number of z~5 quasars to turn up a quasar suitable for measuring HeI absorption (and we illustrate a selection method to identify that quasar). From simulated observations of a suitable z~5 quasar with a 10-meter telescope, we show that a constraint on the spectral slope of the ionizing background at that redshift can be obtained.

Michael R. Santos; Abraham Loeb

2003-04-07

367

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, Lliam Teixeira; Silva Barcellos, Neila Mrcia; de Souza, Jacqueline; de Lana, Marta

2012-06-01

368

Direct spectrophotometric assay of laccase using diazo derivatives of guaiacol.  

PubMed

Laccase (EC 1.10.3.2) is a widespread cuproenzyme able to oxidize various types of phenols and similar aromatic compounds through a one-electron transfer mechanism. The enzyme has already found its way into the market as a biocatalyst. Because of its ability to be paired by electron mediators, the expectation for employing laccases in versatile processes is very high. There are a few spectrophotometric methods for assaying the laccase activity; however, all of them are based on the formation of product(s) resulting from the enzymatic and inevitable succeeding chemical reactions. Use of diazo derivatives of guaiacol (DdG) was developed as a new spectrophotometric method based on substrate depletion allowing direct assessment of enzyme activity has been introduced. This method allows accurate comprehensive kinetic studies of laccases and provides reliable information about the quality of docking of different substrates or one substrate to the active sites of different laccases. Using this method, the kinetic parameters of various DdG carrying different electron donating and withdrawing substituents were used to assay laccase from Neurospora crassa. 2-Methoxy-4-[(4-phenyl)azo]-phenol (K(m) = 93.5 ?M and V = 1.98 ?M/min) was identified as an appropriate substrate for the accurate and routine spectrophotometric based assay of laccases. PMID:21545148

Moshtaghioun, Seyed Mohammad; Haghbeen, Kamahldin; Sahebghadam, Abbas Lotfi; Legge, Raymond L; Khoshneviszadeh, Rabea; Farhadi, Sahar

2011-06-01

369

Multisyringe flow injection spectrophotometric determination of uranium in water samples  

Microsoft Academic Search

A multisyringe flow injection analysis method for the determination of uranium in water samples was developed. The methodology\\u000a was based on the complexation reaction of uranium with arsenazo (III) at pH 2.0. Uranium concentrations were spectrophotometrically\\u000a detected at 649nm using a light emitting diode. Under the optimized conditions, a linear dynamic range from 0.1 to 4.0?gmL?1, a 3? detection limit

Jorge L. Guzmn Mar; Leticia Lpez Martnez; Pedro L. Lpez de Alba; Nancy Ornelas Soto; Vctor Cerd Martn

2009-01-01

370

SPECTROPHOTOMETRIC DETERMINATION OF URANIUM WITH BENZOHYDROXAMIC ACID IN 1- HEXANOL  

Microsoft Academic Search

A spectrophotometric method for quantitatively determining small amounts ; of uranium is based on extraction with 1-hexanol of the colored product formed ; when the uranyl ion reacts with benzohydroxamic acid (CHCONHOH) at ; pH 6.2. The system obeys Beer's law between 7 x 10⁻⁷ and 2 x 10⁻⁵ ; mole of uranyl ion when extracted into 10 ml. of

C. E. Meloan; Paul Holkeboer; W. W. Brandt

1960-01-01

371

A SPECTROPHOTOMETRIC STUDY OF THE HYDROLYSIS OF PLUTONIUM(IV)  

Microsoft Academic Search

The hydrolysis of Pu(IV) in HO and DO was studied by ; means of spectrophotometric measurements at 3300 A and various acidities. The ; data were solved with the least squares method on an IBM computer (704) for the ; hydrolysis constant K = STAPuOH\\/sup 3+\\/!STAH\\/sup +\\/!\\/STAPu\\/sup 4+\\/!. ; Measurements were made at 15.4 and 25.0 deg C, and they

S. W. Rabideau; R. J. Kline

1960-01-01

372

Spectrophotometric determination of iron(III) dimethyldithiocarbamate (ferbam)  

Microsoft Academic Search

A spectrophotometric method was developed for the determination of ferbam (iron(III) dimethyldithiocarbamate) by converting it into an iron-phenanthroline complex, which was then absorbed on microcystalline naphthalene in the presence of tetraphenylborate, and the absorbance was measured at 515 nm against a reagent blank. The molar absorptivity of the complex was 1.2 104l mol?1cm?1. Ten replicate analyses of a sample

Ashok Kumar Malik; A. L. J. Rao

1997-01-01

373

Spectrophotometric determination of sparfloxacin in pharmaceutical formulations using bromothymol blue  

Microsoft Academic Search

A visible light spectrophotometric method is described for the determination of sparfloxacin in tablets. The procedure is based on the complexation of bromothymol blue 0.5% and sparfloxacin to form a compound of yellow colour with maximum absorption at 385 nm. The LambertBeer law was obeyed in the concentration range of 212 mg\\/l. The present study describes a sensitive and accurate

Hrida R. N Marona; Elfrides E. S Schapoval

2001-01-01

374

UV-sensitive indicators based on bromophenol blue and chloral hydrate dyed poly(vinyl butyral)  

Microsoft Academic Search

UV-sensitive indicators based on dyed poly(vinyl butyral) (PVB) containing acid-sensitive dye (bromophenol blue, BPB) and chloral hydrate have been developed and used successfully to measure the integrated UV irradiance. This flexible film changes colour from blue to green and finally to yellow on exposure to UV irradiation. The radiation-induced change in colour was analysed spectrophotometrically at the absorption band maxima

A. A. Abdel-Fattah; M. El-Kelany; F. Abdel-Rehim; A. A. El Miligy

1997-01-01

375

A method for the analysis of organophosphorus pesticide residues in Mexican axolotl  

Microsoft Academic Search

A method based on matrix solid-phase dispersion (MSPD) was developed for quantitative extraction of three organophosphorus pesticides (OPPs) from the Mexican axolotl, Ambystoma mexicanum. The determination was carried out using high- performance liquid chromatography (HPLC) with diode array spectrophotometric UV detection (DAD). The MSPD extraction with octadecylsilyl (C18) sorbent combined with a silica gel clean-up and acetonitrile elution was optimised

Martha P. Garca De Llasera; Leopoldo Cruz-Reyes; Luz E. Vera-Avila

2009-01-01

376

Spectrophotometric determination of Rauwolfia alkaloids: estimation of reserpine in pharmaceuticals.  

PubMed

A simple, sensitive and economically viable spectrophotometric method for the determination of some Rauwolfia alkaloids (ajmaline, ajmalicine, reserpine and yohimbine-HCl) has been developed. The method involves the oxidation of Rauwolfia alkaloids by iron(III) and subsequent complexation of iron(II) with 1,10-phenanthroline, forming a red-colored complex having the maximum absorbance at 510 nm. The method is applied to the determination of reserpine in tablets of pharmaceutical formulations. The common excipients do not interfere with the proposed method. A statistical comparison of these results with those of a reported method shows good agreement and indicates no significant difference in the precision. PMID:15068309

Singh, Dhruv K; Srivastava, Bhavana; Sahu, Archana

2004-03-01

377

Ambient formic acid in southern California air: A comparison of two methods, Fourier transform infrared spectroscopy and alkaline trap-liquid chromatography with UV detection  

SciTech Connect

Formic acid is an ubiquitous component of urban smog. Sources of formic acid in urban air include direct emissions from vehicles and in situ reaction of ozone with olefins. Ambient levels of formic acid in southern California air were first measured some 15 years ago by Hanst et al. using long-path Fourier transform infrared spectroscopy (FTIR). All subsequent studies of formic acid in the Los Angeles area have involved the use of two methods, either FTIR or collection on alkaline traps followed by gas chromatography, ion chromatography, or liquid chromatography analysis with UV detection, ATLC-UV. The Carbon Species Methods Comparison Study (CSMCS), a multilaboratory air quality study carried out in August 1986 at a southern California smog receptor site, provided an opportunity for direct field comparison of the FTIR and alkaline trap methods. The results of the comparison are presented in this brief report.

Grosjean, D. (DGA, Inc., Ventura, CA (USA)); Tuazon, E.C. (Univ. of California, Riverside (USA)); Fujita, E. (California Air Resources Board, Sacramento (USA))

1990-01-01

378

Spectrophotometric estimation of individual flavone glycosides in three Euphorbia species.  

PubMed

Two spectrophotometric methods (conventional and differential) are carried out for the estimation of flavone glycosides (hyperoside and/or kaempferol-3-beta-glucoside) in Euphorbia paralias L., and Euphorbia helioscopia L. The glycosides are extracted with methanol from the aerial parts of the different Euphorbia species, separated on silica gel chromatoplates, and eluted by refluxing with methanol (80%). The absorbance value (conventional method) and the delta absorbance value (differential method) of the prepared glycosidal solutions are measured. The results of both methods are of conveinent reproducibility. PMID:1161795

Abdel-Salam, N A; El-Sayed, M; Khafagy, S M

1975-06-01

379

New spectrophotometric methods for the determinations of hydrogen sulfide present in the samples of lake water, industrial effluents, tender coconut, sugarcane juice and egg  

NASA Astrophysics Data System (ADS)

The new methods are working on the principle that iron(III) is reduced to iron(II) by hydrogen sulfide, catechol and p-toluidine the system 1/hydrogen sulfide the system 2, in acidic medium followed by the reduced iron forming complex with 1,10-phenanthroline with ?max 510 nm. The other two methods are based on redox reactions between electrolytically generated manganese(III) sulfate taken in excess and hydrogen sulfide followed by the unreacted oxidant oxidizing diphenylamine ?max 570 the system 3/barium diphenylamine sulphonate ?max 540 nm, the system 4. The increase/decrease in the color intensity of the dye products of the systems 1 and 2 or 3 and 4 are proportional to the concentration of hydrogen sulfide with its quantification range 0.035-1.40 ?g ml-1/0.14-1.40 ?g ml-1.

Shyla, B.; Nagendrappa, G.

2012-10-01

380

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

381

Simultaneous multicomponent spectrophotometric monitoring of methyl and propyl parabens using multivariate statistical methods after their preconcentration by robust ionic liquid-based dispersive liquid-liquid microextraction.  

PubMed

A powerful and efficient signal-preprocessing technique that combines local and multiscale properties of the wavelet prism with the global filtering capability of orthogonal signal correction (OSC) is applied for pretreatment of spectroscopic data of parabens as model compounds after their preconcentration by robust ionic liquid-based dispersive liquid-liquid microextraction method (IL-DLLME). In the proposed technique, a mixture of a water-immiscible ionic liquid (as extraction solvent) [Hmim][PF6] and disperser solvent is injected into an aqueous sample solution containing one of the IL's ions, NaPF6, as extraction solvent and common ion source. After preconcentration, the absorbance of the extracted compounds was measured in the wavelength range of 200-700 nm. The wavelet orthogonal signal correction with partial least squares (WOSC-PLS) method was then applied for simultaneous determination of each individual compound. Effective parameters, such as amount of IL, volume of the disperser solvent and amount of NaPF6, were inspected by central composite design to identify the most important parameters and their interactions. The effect of pH on the sensitivity and selectivity was studied according to the net analyte signal (NAS) for each component. Under optimum conditions, enrichment factors of the studied compounds were 75 for methyl paraben (MP) and 71 for propyl paraben (PP). Limits of detection for MP and PP were 4.2 and 4.8 ng mL(-)(1), respectively. The root mean square errors of prediction for MP and PP were 0.1046 and 0.1275 ?g mL(-)(1), respectively. The practical applicability of the developed method was examined using hygienic, cosmetic, pharmaceutical and natural water samples. PMID:24317257

Khani, Rouhollah; Ghasemi, Jahan B; Shemirani, Farzaneh

2014-03-25

382

In-situ spectrophotometric probe  

SciTech Connect

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

383

In-situ spectrophotometric probe  

DOEpatents

A spectrophotometric probe is described 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 co-terminal, 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 focusing 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. 5 figs.

Prather, W.S.

1992-12-15

384

Technique of radiation polymerization in fine art conservation: a potentially new method of restoration and preservation. [Uv and electron beams  

Microsoft Academic Search

The technique of using radiation polymerization for the restoration and preservation of art treasures is considered. The processes discussed include both radiation grafting and rapid cure procedures, particularly reactions initiated by uv and eb. Representative examples where the technique has already been used are treated including typical applications with paintings, tapestries, leather and archival repair. The structure of the monomers

J. L. Garnett; G. Major

1982-01-01

385

Quantification of appetite suppressing steroid glycosides from Hoodia gordonii in dried plant material, purified extracts and food products using HPLC-UV and HPLCMS methods  

Microsoft Academic Search

High-performance liquid chromatography (HPLC)-UV and HPLCMass Spectrometry (MS) methods were developed for the quantitative analysis of the family of Hoodia gordonii steroid glycosides with appetite suppressing properties in dried plant material, in purified and enriched extracts and in various prototype food-products fortified with H. gordonii extracts.For solid materials, e.g. dried plants or for non-fatty foods, extraction of the steroid glycosides

Hans-Gerd Janssen; Chris Swindells; Philip Gunning; Weijun Wang; Christian Grn; Krishna Mahabir; Vinesh J. Maharaj; Peter J. Apps

2008-01-01

386

Simultaneous spectrophotometric determination of Fe(III) and Al(III) using orthogonal signal correction-partial least squares calibration method after solidified floating organic drop microextraction.  

PubMed

A solidified floating organic drop microextraction (SFODME) procedure was developed for the simultaneous extraction and preconcentration of Fe(III) and Al(III) from water samples. The method was based on the formation of cationic complexes between Fe(III) and Al(III) and 3,5,7,2',4'-pentahydroxyflavone (morin) which were extracted into 1-undecanol as ion pairs with perchlorate ions. The absorbance of the extracted complexes was then measured in the wavelength range of 300-450 nm. Finally, the concentration of each metal ion was determined by the use of the orthogonal signal correction-partial least squares (OSC-PLS) calibration method. Several experimental parameters that may be affected on the extraction process such as the type and volume of extraction solvent, pH of the aqueous solution, morin and perchlorate concentration and extraction time were optimized. Under the optimum conditions, Fe(III) and Al(III) were determined in the ranges of 0.83-27.00 ?g L(-1) (R(2)=0.9985) and 1.00-32.00 ?g L(-1) (R(2)=0.9979) of Fe(III) and Al(III), respectively. The relative standard deviations (n=6) at 12.80 ?g L(-1) of Fe(III) and 17.00 ?g L(-)(1) of Al(III) were 3.2% and 3.5%, respectively. An enhancement factors of 102 and 96 were obtained for Fe(III) and Al(III) ions, respectively. The procedure was successfully applied to determination of iron and aluminum in steam and water samples of thermal power plant; and the accuracy was assessed through the recovery experiments and independent analysis by electrothermal atomic absorption spectroscopy (ETAAS). PMID:25168229

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

2015-01-25

387

Simultaneous spectrophotometric determination of Fe(III) and Al(III) using orthogonal signal correction-partial least squares calibration method after solidified floating organic drop microextraction  

NASA Astrophysics Data System (ADS)

A solidified floating organic drop microextraction (SFODME) procedure was developed for the simultaneous extraction and preconcentration of Fe(III) and Al(III) from water samples. The method was based on the formation of cationic complexes between Fe(III) and Al(III) and 3,5,7,2?,4?-pentahydroxyflavone (morin) which were extracted into 1-undecanol as ion pairs with perchlorate ions. The absorbance of the extracted complexes was then measured in the wavelength range of 300-450 nm. Finally, the concentration of each metal ion was determined by the use of the orthogonal signal correction-partial least squares (OSC-PLS) calibration method. Several experimental parameters that may be affected on the extraction process such as the type and volume of extraction solvent, pH of the aqueous solution, morin and perchlorate concentration and extraction time were optimized. Under the optimum conditions, Fe(III) and Al(III) were determined in the ranges of 0.83-27.00 ?g L-1 (R2 = 0.9985) and 1.00-32.00 ?g L-1 (R2 = 0.9979) of Fe(III) and Al(III), respectively. The relative standard deviations (n = 6) at 12.80 ?g L-1 of Fe(III) and 17.00 ?g L-1 of Al(III) were 3.2% and 3.5%, respectively. An enhancement factors of 102 and 96 were obtained for Fe(III) and Al(III) ions, respectively. The procedure was successfully applied to determination of iron and aluminum in steam and water samples of thermal power plant; and the accuracy was assessed through the recovery experiments and independent analysis by electrothermal atomic absorption spectroscopy (ETAAS).

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

2015-01-01

388

Development and validation of a novel derivatization method for the determination of lactate in urine and saliva by liquid chromatography with UV and fluorescence detection.  

PubMed

We developed a novel and straightforward derivatization method for the determination of lactate by reversed phase high-performance liquid chromatography (RP-HPLC) with fluorescence and UV detection in biological matrices as urine and saliva. The derivatization of lactate was achieved employing 9-chloromethyl anthracene (9-CMA) as fluorescence reagent, which has never been previously used to obtain a lactate derivative. Lactate reacts with 9-CMA with high selectivity in a very short time, without requiring extraction procedures from the aqueous solution, and the reaction reaches 70% completion in 30 min. The ester derivative obtained can be easily determined by RP-HPLC with fluorescence detection at 410 nm (? ex=365 nm) and UV detection at 365 nm. The method was also optimized in order to allow for the simultaneous determination of lactate and creatinine for the application to urine samples. The lactate calibration curve was linear in the investigated range 2 10(-4)-3 10(-2)mM and the limit of detection, calculated as three times the standard deviation of the blank divided by the calibration curve slope, was 50 nM for both fluorescence and UV detection. Intra-day and inter-day repeatability were lower than 5% and 6%, respectively. The method proposed was successfully applied to the analysis of urine and saliva samples. PMID:25159410

Pellegrini, Davide; Onor, Massimo; Degano, Ilaria; Bramanti, Emilia

2014-12-01

389

Spectrophotometric assay for horseradish peroxidase activity based on pyrocatechol-aniline coupling hydrogen donor.  

PubMed

The hydrogen donor couples pyrocatechol-aniline and phenol-aminoantipyrine in the presence of hydrogen peroxide were compared as chromogens for horseradish peroxidase (HRP) assay. UV-Visible spectroscopy and high-performance liquid chromatography analysis indicated that during the HRP biocatalytic process, pyrocatechol-aniline was converted to a pink-colored reagent with a lambda(max) of 510 nm, which was used in the assay of HRP activity. Electrochemical studies revealed adequate electron transfer ability for this color reagent to serve as a proper mediator for HRP also. Using pyrocatechol-aniline a higher sensitivity and lower detection limit was obtained relative to those of the phenol-aminoantipyrine couple, which is commonly used for HRP assay. A relative standard deviation of 2.9% was obtained for 20 HRP activity measurements, indicating a satisfactory reproducibility for this method. In addition, kinetic parameters of K(m) (12.5mM) and V(max) (12.2 mM min(-1)mg(-1)) were calculated for pyrocatechol-aniline. Regarding the superiority of pyrocatechol-aniline, this couple is suggested to be a better hydrogen donor for the HRP spectrophotometric assay. PMID:17234148

Molaei Rad, A; Ghourchian, H; Moosavi-Movahedi, A A; Hong, J; Nazari, K

2007-03-01

390

51V(n, beta)52Cr reaction for neutron dosimetry: development and assessment of a spectrophotometric method for determination of Cr in vanadium at sub ppm level.  

PubMed

With a view to monitoring the changes in coloration caused by the nuclear reaction 51V(n, beta)52Cr in solution of vanadyl sulphate and using it for neutron dosimetry, electronic absorption spectra of vanadyl sulphate solutions were investigated at different concentrations of chromate impurity in micromolar range. It was observed that the presence of chromate enhances the absorptivity over a wide wavelength range serving essentially as a colouring agent for vanadium matrix, presumably due to charge transfer process. The absorbance at 380 nm varied linearly over a wide concentration range. The limit of detection of chromate obtained is shown to be adequate for detecting neutron-induced chemical transmutation of vanadium to chromium under standard reactor conditions, when used with long path length cells. It was observed that the absorbance does not change on electron irradiation, suggesting that radiolytic effects due to beta decay, if any, do not interfere in the measurement of neutron-induced changes. In addition to its potential for neutron dosimetry, this is the first report of a simple and direct method of estimation of Cr in vanadium matrix at sub ppm level. PMID:15249026

Sastry, M D; Gustafsson, H; Lund, A; Lund, E

2004-08-01

391

Use of Chromatographic (SPE-HPLC) and Spectrophotometric Methods for Differentiation of Salix Species Through Correlation Analysis and FreeViz Projection.  

PubMed

The major concern of the present article is research into the combination of analytical assessment and multi-correlative data interpretation. For this purpose, a high performance liquid chromatography (HPLC) procedure was developed for the simultaneous quantification of salicin, salicylalcohol derivatives, phenolic acids, flavonoids, and monomeric catechins after solid phase extraction (SPE). On the basis of an established and validated HPLC method, 49 different Salix samples were extracted, purified, and analysed. Furthermore, the quantity of total polyphenols (Folin-Ciocalteau colorimetric reaction) and the antioxidant activity (DPPH radical scavenging activity test) were determined and correlated. This yielded correlation coefficients at P-values less than 0.05 of 0.775, 0.967, 0.932, and 0.989 for Salix fragilis, Salix rubens, Salix purpurea (2006), and Salix purpurea (2007), respectively. Correlation with mean values of each species between total polyphenols content and % DPPH inhibition values occurred at a correlation coefficient (r) of 0.851. Linear correlations of quantified HPLC data with DPPH data and with total polyphenols content could also be found for salicin, gentisic acid, naringin, and salicylic acid. Finally, by combining HPLC data with total polyphenols content and antioxidant capacity through 3-D scatter plots and FreeViz data projection, it was shown that primarily the amount of epicatechin and saligenin beside DPPH values and total polyphenols content enable the classification into plant species and further by year of harvest. PMID:21118078

Kasemsook, S; Stecher, G; Fuchsberger, C; Abel, G; Popp, M; Bonn, G K

2010-11-29

392

Spectrophotometric analysis of aqueous mixtures of some chromium (III) complexes. Thesis  

NASA Technical Reports Server (NTRS)

Several methods of determining the relative concentrations of Cr(H2O)5C1(+2) and Cr(H2O)6(+3) are described. The three methods studied are curved resolving methods, used in evaluating spectrophotometric results, mixture results, used in verifying curve resolving techniques, and chromium analysis.

Stevens, G.

1983-01-01

393

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

NASA Astrophysics Data System (ADS)

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.

Sarkar, Priyanka; Bhui, Dipak Kumar; Bar, Harekrishna; Sahoo, Gobinda Prasad; Samanta, Sadhan; Pyne, Santanu; Misra, Ajay

2010-10-01

394

Determination of metformin hydrochloride and glyburide in an antihyperglycemic binary mixture using high-performance liquid chromatographic-UV and spectrometric methods.  

PubMed

Three methods were developed for simultaneous determination of metformin hydrochloride and glyburide in an antihyperglycemic binary mixture without previous separation. In the first method, a reversed-phase HPLC column with acetonitrile-water (60 + 40, v/v) mobile phase at 0.9 mL/min flow rate was used to separate both compounds, with UV detection at 254 nm. Linearity was obtained in the concentration range of 0.06--0.24 microg/mL for glyburide and 1.5-6.0 microg/mL for metformin hydrochloride. The second method depended on first- and second-derivative UV spectrometry with zero-crossing measurements. The first-derivative amplitude at 261 nm was selected for the assay of glyburide, and the second-derivative amplitude at 235 nm was selected for the assay of metformin hydrochloride. The third method depended on measuring the first derivative of the ratio-spectra at 241 nm for glyburide and 227 nm for metformin hydrochloride. For the second and third methods, Beer's law was obeyed in the range of 10-55 microg/mL for glyburide and 20-200 microg/mL for metformin. The proposed methods were extensively validated and applied for the analysis of some pharmaceutical formulations containing binary mixtures of the mentioned drugs. PMID:20334175

Salem, Hesham

2010-01-01

395

Spectrophotometric determination of uranium in natural waters after preconcentration on TBP-plasticized dibenzoylmethane-loaded polyurethane foams  

Microsoft Academic Search

A method is presented for the spectrophotometric determination of uranium in natural waters after a preconcentration step involving percolation of a suitable aliquot of the water sample whose pH is adjusted to 6.06.5 through a TBP-plasticized dibenzoylmethane-loaded polyurethane foam bed. Uranium on the foam is eluted with 0.6M HCl solution and then determined spectrophotometrically using arsenazo III as a chromogenic

M. Aziz; Sh. G. Beheir; K. Shakir

1993-01-01

396

Comparison of various sensitive and selective spectrophotometric assays of environmental cyanide  

Microsoft Academic Search

A review is presented to show the advantages involved in the use of some new spectrophotometric cyanide (CN) assays, which are highly sensitive and selective, quick and affordable. Among these, the ninhydrin-based assay, the method based on CN reaction with resorcinol, as well as the Berthelot reaction were found to be highly selective. The old Aldridge 1 method, based on

Gabi Drochioiu; Karin Popa; Doina Humelnicu; Manuela Murariu; Ion Sandu; Alexandru Cecal

2008-01-01

397

Spectrophotometric Determination of Certain Phenothiazines and Their Dosage Forms Using Bromophenol Blue  

Microsoft Academic Search

A simple and rapid spectrophotometric method for the determination of seven phenothiazine derivatives has been performed either in pure form or in their dosage forms. The method is based upon the interaction of the drug in dry chloroform with bromophenol blue in the same solvent to produce a stable yellow ion-pair complex which absorbs at 410 nm, with high apparent

M. M. El-kerdawy; M. A. Maustafa; S. M. El-Ashry; D. R. El-Wasf

1993-01-01

398

Spectrophotometric Determination of Copper with 2, 2?-Biquinolyl and Bromophenol Blue  

Microsoft Academic Search

A sensitive and selective method for the determination of copper is described. The copper(l) ?2, 2? -biquinolyl chelate is extracted into 3-methyl-1-butanol, and then the chelate is associated with bromophenol blue. The blue ion-associate is used for the spectrophotometric determination of copper. This method was applied to the determination of copper in nickel-base alloys.

Keiichi Sekine; Hiroshi Onishi

1974-01-01

399

Spectrophotometric determination of amino acids using metol and sodium hypochlorite or chloramine-T  

Microsoft Academic Search

Summary Simple and sensitive spectrophotometric methods for the determination of proline, hydroxyproline, aspartic acid, arginine and histidine, based on the formation of a coloured species with metol and sodium hypochlorite or chloramine-T are described. The effect of other amino acids and the best conditions for forming coloured complexes have been studied. The methods are applicable to the determination of the

M. K. Tummuru; K. Ekambareswara Rao; C. S. P. Sastry

1984-01-01

400

Comparative Study of Three Methods for Affinity Measurements: Capillary Electrophoresis Coupled with UV Detection and Mass Spectrometry, and Direct Infusion Mass Spectrometry  

NASA Astrophysics Data System (ADS)

We present affinity capillary electrophoresis and mass spectrometry (ACE-MS) as a comprehensive separation technique for label-free solution-based affinity analysis. The application of ACE-MS for measuring affinity constants between eight small molecule drugs [ibuprofen, s-flurbiprofen, diclofenac, phenylbutazone, naproxen, folic acid, resveratrol, and 4,4'-(propane-1,3-diyl) dibenzoic acid] and ?-cyclodextrin is described. We couple on-line ACE with MS to combine the separation and kinetic capability of ACE together with the molecular weight and structural elucidation of MS in one system. To understand the full potential of ACE-MS, we compare it with two other methods: Direct infusion mass spectrometry (DIMS) and ACE with UV detection (ACE-UV). After the evaluation, DIMS provides less reliable equilibrium dissociation constants than separation-based ACE-UV and ACE-MS, and cannot be used solely for the study of noncovalent interactions. ACE-MS determines apparent dissociation constants for all reacting small molecules in a mixture, even in cases when drugs overlap with each other during separation. The ability of ACE-MS to interact, separate, and rapidly scan through m/z can facilitate the simultaneous affinity analysis of multiple interacting pairs, potentially leading to the high-throughput screening of drug candidates.

Mironov, Gleb G.; Logie, Jennifer; Okhonin, Victor; Renaud, Justin B.; Mayer, Paul M.; Berezovski, Maxim V.

2012-07-01

401

Excimer UV-assisted rapid thermal annealing of PbLa(Zr ,Ti)O3 thin films by a sol-gel deposition method  

NASA Astrophysics Data System (ADS)

Excimer UV-assisted rapid thermal annealing (UV-RTA) process has been employed to fabricate sol-gel derived ferroelectric Pb0.97La0.03(Zr0.53Ti0.47)O3 (PLZT) thin films on Pt /Ti/SiO2/Si substrates. X-ray diffraction analysis showed that the single phase PLZT thin film can be achieved at a relatively low processing temperature of 580C. The films appeared to have improved dielectric properties with dielectric constant (?) and loss (tan?) values of 3300 and 0.03 at 1kHz, respectively. Comparatively good remnant polarization (Pr) value of 36?Ccm-2 and coercive field (Ec) value of 60kVcm-1 along with a good fatigue resistance up to 1010 switching cycles have been observed. This method of fabrication of the Pb-based material with the aid of UV-RTA at a comparatively lower temperature opens the door for their better employability in the Si integrated circuit technology.

Shannigrahi, S. R.; Lim, X.; Tay, F. E. H.

2007-01-01

402

Variable path length spectrophotometric probe  

DOEpatents

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, Patrick E. (157 Greenwood Dr., Martiney, GA 30907); McCarty, Jerry E. (104 Recreation Dr., Aiken, SC 29803); Haggard, Ricky A. (1144 Thornwood Drive, North Augusta, SC 29891)

1992-01-01

403

Spectrophotometric Calibration System for DECam  

NASA Astrophysics Data System (ADS)

We present a spectrophotometric calibration system that will be implemented as part of the DES DECam project at the Blanco 4 meter at CTIO. Our calibration system uses a 2nm wide tunable source to measure the instrumental response function of the telescope from 300nm up to 1100nm. This calibration will be performed at regular interval during the survey to monitor any change in the transmission function. The system consists of a monochromator based tunable light source that provides illumination on a dome flat that is monitored by calibrated photodiodes and allow us to measure the throughput as a function of wavelength. Our system has an output power of 2 mW, equivalent to a flux of approximately 800 photons/s per pixel on DECam. We also present results from the deployment of a prototype of this system at the Swope and DuPont telescopes at Las Campanas Observatory for the calibration of the photometric equipment used in the Carnegie Supernova Project.

Rheault, Jean-Philippe; DePoy, D.; Marshall, J.; Carona, D.; Cook, K.; Behm, T.; Allen, R.

2011-01-01

404

Simple and universal HPLC-UV method to determine cimetidine, ranitidine, famotidine and nizatidine in urine: application to the analysis of ranitidine and its metabolites in human volunteers.  

PubMed

A validated, simple and universal HPLC-UV method for the determination of cimetidine, famotidine, nizatidine and ranitidine in human urine is presented. This is the first single HPLC method reported for the analysis of all four H(2) antagonists in human biological samples. This method was also utilized for the analysis of ranitidine and its metabolites in human urine. All calibration curves showed good linear regression (r(2)>0.9960) within test ranges. The method showed good precision and accuracy with overall intra- and inter-day variations of 0.2-13.6% and 0.2-12.1%, respectively. Separation of ranitidine and its metabolites using this assay provided significantly improved resolution, precision and accuracy compared to previously reported methods. The assay was successfully applied to a human volunteer study using ranitidine as the model compound. PMID:18006395

Ashiru, Diane A I; Patel, Rajesh; Basit, Abdul W

2007-12-15

405

Spectrophotometric and spectrofluorimetric determination of atomoxetine in pharmaceutical preparations.  

PubMed

Visible spectrophotometric and spectrofluorimetric methods were developed for the determination of atomoxetine in pharmaceutical preparations. The spectrophotometric method was based on a nucleophilic substitution reaction of atomoxetine with 1,2-naphthoquinone-4-sulphonate (NQS) in an alkaline medium to form an orange-colored product. The absorbance-concentration plot is rectilinear over the range 5-40 microg mL(-1). The limits of detection and quantification were calculated to be 0.02 microg mL(-1) and 0.06 microg mL(-1), respectively. The spectrofluorimetric method was based on the derivatization reaction of 4-chloro-7-nitro-2,1,3-benzoxadiazole (NBD-Cl) with atomoxetine to produce a fluorescent derivative. The formed highly fluorescent derivative that was measured at 462 nm after excitation at 533 nm. The fluorescence-concentration plot is rectilinear over the range 10-500 ng mL(-1). The limits of detection and quantification were calculated to be 0.19 ng mL(-1) and 0.57 ng mL(-1). The analytical performance of both methods was fully validated, and the results were satisfactory. The methods have been successfully applied for the determination of the studied drug in capsules and the results obtained ware in good agreement with those obtained by the reference method. PMID:22204127

Ulu, S T

2011-11-01

406

A UV-transparent passive concentrator/spectrum deconvolution method for simultaneous detection of endocrine disrupting chemicals (EDCs) and related contaminants in natural waters.  

PubMed

Suspected endocrine disrupting chemicals (EDCs) have been widely detected in the environment, and are a source of increasing concern. One of the major challenges in assessing the risk associated with EDCs in the environment is that their environmental concentrations are typically extremely low - on the order of ngL(-1) to microgL(-1) - making them difficult to quantify without extensive pre-concentration procedures. Further complicating their detection is the fact that they are present in mixtures, sometimes with tens to hundreds of other compounds (pharmaceuticals, personal care products, detergents, natural organic matter). The objective of the work described here was to develop a method for rapid monitoring and detection of EDCs at trace concentrations in natural waters. The method makes use of a UV-transparent polymer-based concentrator to be used as a passive sampling device. The UV-transparent polymer-based concentrator serves both as a solid phase extraction medium to concentrate EDCs for analysis and exclude many compounds likely to interfere with detection (fines, macromolecules such as organic matter, ionic surfactants), and as an analytical optical cell, allowing rapid EDC quantification without labor-intensive pre-concentration procedures. A full-spectrum deconvolution technique is used to determine EDC concentrations from measured UV absorbance spectra in the polymer. Experiments were conducted to measure partitioning rate behavior and partition coefficients between the selected polymer (a functional polydimethylsiloxane) and water for seven compounds known or suspected of being endocrine disruptors: estrone, progesterone, estradiol, 2,6-di-tert-butyl-1,4-benzoquinone, phenanthrene, triclosan, and 4-nonylphenol. The method was tested for its ability to detect and quantify individual compounds in mixtures containing up to six components. Results show the method to have selectivity suitable for rapid screening applications at many sites where multiple compounds are present. PMID:19539350

Kibbey, Tohren C G; Chen, Lixia; Singhaputtangkul, Natee; Sabatini, David A

2009-08-01

407

Technique of radiation polymerization in fine art conservation: a potentially new method of restoration and preservation. [Uv and electron beams  

SciTech Connect

The technique of using radiation polymerization for the restoration and preservation of art treasures is considered. The processes discussed include both radiation grafting and rapid cure procedures, particularly reactions initiated by uv and eb. Representative examples where the technique has already been used are treated including typical applications with paintings, tapestries, leather and archival repair. The structure of the monomers and oligomers used in both grafting and rapid cure systems is outlined. The experimental conditions where grafting may occur during radiation rapid cure processing are discussed. Possible future developments of the technique are outlined. 1 figure, 8 tables.

Garnett, J.L. (Univ. of New South Wales, Kensington, Australia); Major, G.

1982-01-01

408

Simultaneous determination of 15 phenolic compounds and caffeine in teas and mate using RP-HPLC/UV detection: Method development and optimization of extraction process.  

PubMed

A reversed-phase high performance liquid chromatographic coupled to ultraviolet detection (RP-HPLC/UV) method was developed for simultaneous determination of 15 phenolic compounds and caffeine in TEAS (green tea, oolong tea, black tea and mate). Furthermore, the extraction process of total phenolic contents (TPC) from TEAS were optimized using response surface methodology (RSM) based on a central composite design (CCD) and then applied to extraction of TEAS. The best conditions obtained using the model were as follow: green tea - extraction time of 123min, extraction temperature of 70C and ethanol concentration of 75%, oolong tea - extraction time of 98min, extraction temperature of 70C and ethanol concentration of 69%, black tea - extraction time of 105min, extraction temperature of 71C and ethanol concentration of 63%, and mate - extraction time of 103min, extraction temperature of 71C and ethanol concentration of 61%. Among the extraction methods used in this study, heat-reflux extraction was found to result in the highest values of TPC. The chromatographic peaks of the 16 studied compounds were successfully identified by comparing their retention time and UV spectra with the reference standards. Method validation was performed by means of linearity, sensitivity, selectivity, accuracy and precision. The developed method was found to be simple, specific and reliable and is suited for routine analysis of phenolic compounds and caffeine in TEAS. PMID:25442580

Bae, In Kyung; Ham, Hyeon Mi; Jeong, Min Hee; Kim, Dong Ho; Kim, Ho Jin

2015-04-01

409

Telescope Spectrophotometric and Absolute Flux Calibration, and National Security Applications, Using a Tunable Laser on a Satellite  

E-print Network

We propose a tunable laser-based satellite-mounted spectrophotometric and absolute flux calibration system, to be utilized by ground- and space-based telescopes. As spectrophotometric calibration may play a significant role in the accuracy of photometric redshift measurement, and photometric redshift accuracy is important for measuring dark energy using SNIa, weak gravitational lensing, and baryon oscillations, a method for reducing such uncertainties is needed. We propose to improve spectrophotometric calibration, currently obtained using standard stars, by placing a tunable laser and a wide-angle light source on a satellite by early next decade (perhaps included in the upgrade to the GPS satellite network) to improve absolute flux calibration and relative spectrophotometric calibration across the visible and near-infrared spectrum. As well as fundamental astrophysical applications, the system proposed here potentially has broad utility for defense and national security applications such as ground target illumination and space communication.

Justin Albert; William Burgett; Jason Rhodes

2006-05-19

410

Column comparison and method development for the analysis of short-chain carboxylic acids by zwitterionic hydrophilic interaction liquid chromatography with UV detection.  

PubMed

Short-chain carboxylic acids are relevant in pharmaceutical, food quality control, and biomedical analysis. In this study, 11 acids commonly found in drugs and in food products were selected. Wine was chosen as matrix for testing the method. The test compounds were used for comparing the selectivity of four 150 2.1 mm zwitterionic hydrophilic interaction LC (HILIC) columns (ZIC-HILIC 5 ?m, 200 , and 3.5 ?m, 100 , ZIC-pHILIC 5 ?m, ZIC-cHILIC 3 ?m, 100 ) while varying the conditions to optimize for low UV wavelength detection and achieve high sensitivity. Retention using potassium phosphate and ammonium carbonate as mobile-phase components at pH 6.0, 7.5, and 8.5-8.9 was studied considering recent hypotheses on HILIC mechanism-related with the Hofmeister series effect and ion hydration. An isocratic method with UV detection at 200 nm and mobile phase consisting of 75% acetonitrile and 10 mM potassium phosphate at pH 6.0 applied to a ZIC-cHILIC column was found provisionally optimal and partially validated for the 11 analytes. Satisfactory results (R(2) from 0.9940 to >0.9999), and recoveries from 93-106% for all analytes evidenced the method as suitable for wine analysis. To the best of our knowledge, no previous study has reported on the direct ZIC-HILIC separation and UV detection of the acids considered here in wine. PMID:24124031

Marrubini, Giorgio; Pedrali, Alice; Hemstrm, Petrus; Jonsson, Tobias; Appelblad, Patrik; Massolini, Gabriella

2013-11-01

411

Extraction and spectrophotometric determination of uranium(VI)  

Microsoft Academic Search

A selective method for the solvent extraction and spectrophotometric determination of uranium(VI) is described. Uranium can be extracted into chloroform at pH 6.0 with N-m-chlorophenyl-2-theno-hydroxamic acid (N-m-CPTHA) and determined by spectrophotometry using 1-(2-pyridylazo)-2-naphthol (PAN). The molar absorptivity is 1.50104 1mol1cm1 at 560 nm. The system obeys Beer's law within the range 0.9520.00 ppm of uranium. Alternatively, a back-extraction procedure was

Y. K. Agrawal; V. J. Bhatt

1986-01-01

412

Spectrophotometric determination of ?-adrenergic blocking agents in pharmaceutical formulations  

Microsoft Academic Search

Simple, rapid and sensitive spectrophotometric procedures were developed for the analysis of atenolol, timolol maleate, propranolol hydrochloride, metoprolol tartarate, betaxolol hydrochloride, levobunolol hydrochloride and bisprolol fumarate in pure form as well as in their pharmaceutical formulations. The methods are based on the reaction of these drugs as n-electron donors with the sigma-acceptor iodine, and the pi-acceptors: 7,7,8,8-tetracyanoquinodimethane, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, tetracyanoethylene, 2,3,5,6-tetrabromo-1,4-benzoquinone

Hesham Salem

2002-01-01