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1

A validated UV spectrophotometric method for determination of duloxetine hydrochloride.  

PubMed

A simple, sensitive and accurate UV spectrophotometric method was developed for the assay of duloxetine hydrochloride in raw material and capsules. Validation of the method yielded good results concerning range, linearity, precision and accuracy. The absorbance was measured at 290 nm for duloxetine capsule solution. The linearity range was found to be 5-50 microg/mL for the drug. It was found that the excipients in the commercial formulation did not interfere with the methods. PMID:17663186

Kamila, M M; Mondal, N; Ghosh, L K

2007-06-01

2

Analysis of glimepiride by using derivative UV spectrophotometric method.  

PubMed

Glimepiride (Amaryl), which is a new oral antidiabetic drug in the sulfonylurea class, was analysed by using second order derivative UV spectrophotometry. The quantification of glimepiride in dimethylformamide was performed in the wavelength range of 245-290 nm at N = 6, ?lambda = 21. The second order derivative spectra was calculated using peak to peak (lambdaDMF = 263.3-268.2 nm), peak to zero (lambdaDMF = 268.2 nm) and tangent (lambdaDMF = 263.3-271.8 nm) method for calibration curves, the linearity range of 1.00-500.00 microg ml(-1) by using the second order derivative UV spectrophotometric method. The developed method was applied to directly and easily to the analysis of the pharmaceutical tablet preparations. R.S.D. were found to be 4.18% (Amaryl tablet; 1 mg) and 2.21% (Amaryl tablet; 2 mg). The method was completely validated and proven to be rugged. The limit of quantitation and the limit of detection were found as 1.00 and 0.4 microg ml(-1), respectively. This validated derivative UV spectrophotometric method is potentially useful for a routine laboratory because of its simplicity, rapidity, sensitivity, precision and accuracy. PMID:11199230

Altinöz, S; Tekeli, D

2001-01-01

3

Simultaneous Estimation of Esomeprazole and Domperidone by UV Spectrophotometric Method  

PubMed Central

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

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

2008-01-01

4

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

PubMed Central

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

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

2014-01-01

5

Rutin in buckwheat herbs grown at different UV-B radiation levels: comparison of two UV spectrophotometric and an HPLC method.  

PubMed

Rutin is an antioxidant with many interesting pharmacological effects. It can also be found in buckwheat (Fagopyrum esculentum Moench). UV radiation stimulates the activity of enzymes of the phenylpropanoid pathway and there is some evidence that it influences the rutin content in plants. The aim of the present research was (1) to examine the influence of different levels of UV-B radiation on rutin content and (2) to compare the results obtained by three analytical methods. The plants were grown under three UV-B levels: reduced, ambient and enhanced, simulating 17% ozone depletion. Analyses were performed by HPLC and two spectrophotometric methods. In one, the absorbancies were measured at 420 nm with and without the addition of AlCl(3). In another method the concentration was calculated from absorbancies at 352.5 nm and 366.5 nm according to the Official Methods of Analysis of AOAC International. The highest amounts of rutin were found in flowers, followed by leaves and stems. A comparison of the different treatments revealed that the highest amounts of rutin were in plants grown under ambient radiation, followed by the plants cultivated under enhanced UV-B and then under reduced UV-B radiation. Treatments caused more effect on leaves than on flowers. Leaves developed under ambient light conditions contained 97% more rutin than leaves grown under reduced UV-B radiation. In flowers, the contents differed by 19% only. The results obtained using the three methods showed a good correlation, but the absolute differences were surprisingly high. The AOAC and the AlCl(3) methods gave, on average, 140% and 30% higher results than HPLC, respectively. PMID:12147730

Kreft, Samo; Strukelj, Borut; Gaberscik, Alenka; Kreft, Ivan

2002-08-01

6

Novel UV-spectrophotometric method for quantitative estimation of furazolidone using mixed hydrotropic agent.  

PubMed

A novel, eco friendly, accurate, sensitive, economic and safe spectrophotometric method was developed by application of mixed hydrotropy using 2 M sodium acetate, 8 M urea, 2 M niacinamide and 2 M sodium benzoate solution (25:25:25:25% V/V) as hydrotropic agent, for the solubalizing of poorly water-soluble Furazolidone (FZ) (solubility:- 3.64e-01 mg/mL in water). There were more than 32 times enhancements in the solubility of FZ were found in mixed hydrotropic solution as compared to solubilities in distilled water. FZ shows maximum absorbance at 360 nm where sodium acetate, urea, niacinamide, sodium benzoate and other tablets excipients did not show any absorbance above 300 nm, and thus no interference in the estimation was seen. FZ was obeyed Beers law in the concentration range of 10 to 50 ?g/ml (r(2)=0.9992) in mixed hydrotropic solvent with mean recovery ranging from 97.32% to 98.9%. Proposed method is new, simple, economic, safe, rapid, accurate and reproducible and was validated according to ICH guidelines and values of accuracy, precision and other statistical analysis were found to be in good accordance with the prescribed values. PMID:23261742

Jain, Nilesh; Jain, Ruchi; Jain, Deepak Kumar; Maheshwari, Rajesh Kumar; Jain, Surendra

2013-01-01

7

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

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

8

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

PubMed

New, simple and cost effective UV-spectrophotometric methods were developed for the estimation of gatifloxacin in bulk and pharmaceutical formulations. Gatifloxacin was estimated at 286 nm in 100 mM phosphate buffer (pH 7.4) and 292 nm in 100 mM hydrochloric acid (pH 1.2). Linearity range was found to be 1-18 mug ml(-1) (regression equation: absorbance=0.0684 x Concentration in microg ml(-1) + 0.0050; r2 = 0.9998) in the phosphate buffer (pH 7.4) and 1-14 microg ml(-1) (regression equation: absorbance = 0.0864 x Concentration in microg ml(-1) + 0.0027; r2 = 0.9999) in hydrochloric acid medium (pH 1.2). The apparent molar absorptivity was found to be 2.62 x 10(4) l mol(-1) cm(-1) in the phosphate buffer and 3.25 x 10(4) l mol(-1) cm(-1) in hydrochloric acid media. In both the proposed methods sandell's sensitivity was found to be about 0.01 microg cm(-2)/0.001A. These methods were tested and validated for various parameters according to ICH guidelines and USP. The quantitation limits were found to be 0.312 and 0.3 microg ml(-1) in the phosphate buffer and hydrochloric acid medium, respectively. The proposed methods were successfully applied for the determination of gatifloxacin in pharmaceutical formulations (tablets, injection and ophthalmic solution). The results demonstrated that the procedure is accurate, precise and reproducible (relative standard deviation <2%), while being simple, cheap and less time consuming and can be suitably applied for the estimation of gatifloxacin in different dosage forms and dissolution studies. PMID:16226753

Venugopal, K; Saha, Ranendra N

2005-01-01

9

Development and Validation of UV-Visible Spectrophotometric Method for Simultaneous Determination of Eperisone and Paracetamol in Solid Dosage Form  

PubMed Central

Purpose: Eperisone Hydrochloride (EPE) is a potent new generation antispasmodic drug which is used in the treatment of moderate to severe pain in combination with Paracetamol (PAR). Both drugs are available in tablet dosage form in combination with a dose of 50 mg for EPE and 325 mg PAR respectively. Methods: The method is based upon Q-absorption ratio method for the simultaneous determination of the EPE and PAR. Absorption ratio method is used for the ratio of the absorption at two selected wavelength one of which is the iso-absorptive point and other being the ?max of one of the two components. EPE and PAR shows their iso-absorptive point at 260 nm in methanol, the second wavelength used is 249 nm which is the ?max of PAR in methanol. Results: The linearity was obtained in the concentration range of 5-25 ?g/mL for EPE and 2-10 ?g/mL for PAR. The proposed method was effectively applied to tablet dosage form for estimation of both drugs. The accuracy and reproducibility results are close to 100% with 2% RSD. Results of the analysis were validated statistically and found to be satisfactory. The results of proposed method have been validated as per ICH guidelines. Conclusion: A simple, precise and economical spectrophotometric method has been developed for the estimation of EPE and PAR in pharmaceutical formulation.

Khanage, Shantaram Gajanan; Mohite, Popat Baban; Jadhav, Sandeep

2013-01-01

10

Development and Validation of UV-Visible Spectrophotometric Method for Simultaneous Determination of Eperisone and Paracetamol in Solid Dosage Form.  

PubMed

Purpose: Eperisone Hydrochloride (EPE) is a potent new generation antispasmodic drug which is used in the treatment of moderate to severe pain in combination with Paracetamol (PAR). Both drugs are available in tablet dosage form in combination with a dose of 50 mg for EPE and 325 mg PAR respectively. Methods: The method is based upon Q-absorption ratio method for the simultaneous determination of the EPE and PAR. Absorption ratio method is used for the ratio of the absorption at two selected wavelength one of which is the iso-absorptive point and other being the ?max of one of the two components. EPE and PAR shows their iso-absorptive point at 260 nm in methanol, the second wavelength used is 249 nm which is the ?max of PAR in methanol. Results: The linearity was obtained in the concentration range of 5-25 ?g/mL for EPE and 2-10 ?g/mL for PAR. The proposed method was effectively applied to tablet dosage form for estimation of both drugs. The accuracy and reproducibility results are close to 100% with 2% RSD. Results of the analysis were validated statistically and found to be satisfactory. The results of proposed method have been validated as per ICH guidelines. Conclusion: A simple, precise and economical spectrophotometric method has been developed for the estimation of EPE and PAR in pharmaceutical formulation. PMID:24312876

Khanage, Shantaram Gajanan; Mohite, Popat Baban; Jadhav, Sandeep

2013-01-01

11

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

PubMed

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

Datta, Kakali; Mukherjee, Asok K

2005-11-01

12

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

NASA Astrophysics Data System (ADS)

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

Datta, Kakali; Mukherjee, Asok K.

2005-11-01

13

Chemometrics-Assisted UV Spectrophotometric and RP-HPLC Methods for the Simultaneous Determination of Tolperisone Hydrochloride and Diclofenac Sodium in their Combined Pharmaceutical Formulation  

PubMed Central

Chemometrics-assisted UV spectrophotometric and RP-HPLC methods are presented for the simultaneous determination of tolperisone hydrochloride (TOL) and diclofenac sodium (DIC) from their combined pharmaceutical dosage form. Chemometric methods are based on principal component regression and partial least-square regression models. Two sets of standard mixtures, calibration sets, and validation sets were prepared. Both models were optimized to quantify each drug in the mixture using the information included in the UV absorption spectra of the appropriate solution in the range 241–290 nm with the intervals ? = 1 nm at 50 wavelengths. The optimized models were successfully applied to the simultaneous determination of these drugs in synthetic mixture and pharmaceutical formulation. In addition, an HPLC method was developed using a reversed-phase C18 column at ambient temperature with a mobile phase consisting of methanol:acetonitrile:water (60:30:10 v/v/v), pH-adjusted to 3.0, with UV detection at 275 nm. The methods were validated in terms of linearity, accuracy, precision, sensitivity, specificity, and robustness in the range of 3–30 ?g/mL for TOL and 1–10 ?g/mL for DIC. The robustness of the HPLC method was tested using an experimental design approach. The developed HPLC method, and the PCR and PLS models were used to determine the amount of TOL and DIC in tablets. The data obtained from the PCR and PLS models were not significantly different from those obtained from the HPLC method at 95% confidence limit.

Gohel, Nikunj Rameshbhai; Patel, Bhavin Kiritbhai; Parmar, Vijaykumar Kunvarji

2013-01-01

14

Second-Order Derivative UV Spectrophotometric Method for the Determination of Fesoterodine and Comparison with LC, CE and LC-MS/MS in Commercial Extended-Release Tablets.  

PubMed

The present work describes a second-order derivative UV spectrophotometric method for determination of a potent antimuscarinic drug, fesoterodine, in extended-release tablets. The method was developed and satisfactory validated according to ICH guideline with respect to specificity, linearity, precision, accuracy, and robustness. The response was linear in the concentration range of 2-24 µg mL-1 (r2 = 0.9999, n = 7) at wavelength 228 nm, which was the zero crossing point of excipient solutions. The detection and quantitation limits were 0.38 and 1.27 µg mL-1, respectively. Precision and accuracy data evaluated by relative standard deviation were lower than 2%. The method proved to be robust by a Plackett-Burman design evaluation. It is simple, it has low cost, and it has low use of polluting reagents. Therefore, the proposed method was successfully applied for the quantitative analysis of fesoterodine in commercial tablets, and the results were compared to validated methods by liquid chromatography, capillary electrophoresis and liquid chromatography-tandem mass spectrometry showing non-significant difference (P > 0.05). PMID:24061183

Sangoi, Maximiliano S; Todeschini, Vítor; Steppe, Martin

2012-03-01

15

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

Microsoft Academic Search

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

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

1999-01-01

16

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

PubMed Central

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

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

2012-01-01

17

Visible spectrophotometric method for amiodarone.  

PubMed

Amiodarone is an antiarrhythmic agent used for various types of tachyarrhythmia, both ventricular and supraventricular (atrial) arrhythmia. A spectrophotometric method for the assay of amiodarone was established. Based on the reduction of potassium ferricyanide in hydrochloric acid medium to potassium ferrocyanide forming a blue colored complex ferric ferrocyanide with Fe (III) ions. The compound was most stable in a mixture of ethylic alcohol and water (2:1, v/v) and it had an absorption maximum at 725 nm. The data were according to the Lambert-Beer Law in the concentration range of 0.5-5.0 microg/sample: correlation and coefficient R = 0.99977, R2 = 0.999541, slope of the line 0.12775, intercept 0.042077. The detection limit (DL) was 0.1032 microg/sample and the quantification limit (QL) 0.344 microg/ sample. PMID:23077917

Bosînceanu, Andreea; Popa, Gra?iela; Tântaru, Gladiola; Popovici, Iuliana

2012-01-01

18

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

PubMed

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

Stanisz, Beata; Regulska, Katarzyna; Kolasa, Kinga

2011-01-01

19

UV-spectrophotometric determination of glycyrrhizic acid in Glycyrrhiza glabra  

Microsoft Academic Search

Summary  A 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 µg\\/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

20

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

Microsoft Academic Search

Three methods are presented for the simultaneous determination of lamivudine and zidovudine. The first method depends on first derivative UV spectrophotometry, with zero-crossing and peak-to-base measurement. The first derivative amplitudes at 265.6 and 271.6nm were selected for the assay of lamivudine and zidovudine, respectively. The second method depends on first derivative of the ratio-spectra by measurements of the amplitudes at

Bengi Uslu; Sibel A Özkan

2002-01-01

21

Visible spectrophotometric and first-derivative UV spectrophotometric determination of rifampicin and isoniazid in pharmaceutical preparations  

Microsoft Academic Search

Two methods are described for the determination of rifampicin and isoniazid in mixtures by visible spectrophotometry and first-derivative ultraviolet spectrophotometry. The absorbance at 475 nm in buffer solution pH 7.4 was employed to determine rifampicin after applying the three-point correction technique between 420 and 520 nm, while the amplitude of the first-derivative spectrophotometric spectrum at 257 nm in HCl 0.012

S. A Benetton; E. R. M Kedor-Hackmann; M. I. R. M Santoro; V. M Borges

1998-01-01

22

Simultaneous UV Spectrophotometric Estimation of Ambroxol Hydrochloride and Levocetirizine Dihydrochloride  

PubMed Central

A novel, simple, sensitive and rapid spectrophotometric method has been developed for simultaneous estimation of ambroxol hydrochloride and levocetirizine dihydrochloride. The method involved solving simultaneous equations based on measurement of absorbance at two wavelengths 242 nm and 231 nm, the ? max of ambroxol hydrochloride and levocetirizine dihydrochloride, respectively. Beer's law was obeyed in the concentration range 10–50 ?g/ml and 8–24 ?g/ml for ambroxol hydrochloride and levocetirizine dihydrochloride respectively. Results of the method were validated statistically and by recovery studies.

Prabhu, S. Lakshmana; Shirwaikar, A. A.; Shirwaikar, Annie; Kumar, C. Dinesh; Kumar, G. Aravind

2008-01-01

23

Simultaneous UV Spectrophotometric Estimation of Ambroxol Hydrochloride and Levocetirizine Dihydrochloride.  

PubMed

A novel, simple, sensitive and rapid spectrophotometric method has been developed for simultaneous estimation of ambroxol hydrochloride and levocetirizine dihydrochloride. The method involved solving simultaneous equations based on measurement of absorbance at two wavelengths 242 nm and 231 nm, the gamma max of ambroxol hydrochloride and levocetirizine dihydrochloride, respectively. Beer's law was obeyed in the concentration range 10-50 mug/ml and 8-24 mug/ml for ambroxol hydrochloride and levocetirizine dihydrochloride respectively. Results of the method were validated statistically and by recovery studies. PMID:20046721

Prabhu, S Lakshmana; Shirwaikar, A A; Shirwaikar, Annie; Kumar, C Dinesh; Kumar, G Aravind

2008-01-01

24

Determination of total chromium in tannery waste water by inductively coupled plasma-atomic emission spectrometry, flame atomic absorption spectrometry and UV-visible spectrophotometric methods.  

PubMed

The determination of total chromium in different streams of tannery effluents were carried out by the digestion of samples in a HNO(3)/H(2)SO(4) mixture followed by KMnO(4) oxidation, which resulted in the complete conversion of Cr(III) to Cr(VI). The Cr(VI) (Cr(2)O(7)(2-)) species present in these samples were estimated by inductively coupled plasma-atomic emission spectrometry (ICP-AES), flame atomic absorption spectrometry (FAAS) and UV-visible spectrophotometry (1,5-diphenyl carbazide method). The results obtained from these methods were critically evaluated. UV-visible spectrophotometry was found to be better suited for this analysis when compared with the other two methods. Since these solutions contain relatively high concentrations of chromium (200-2400 mg/l), the need for preconcentration did not arise. The higher values obtained in the case of ICP-AES and FAAS methods can be attributed to the matrix effect arising out of high concentration of mineral acids and electrolytes. In addition, the values obtained in the latter methods (ICP-AES and FAAS) are comparable with each other, indicating that the interferences influence the results almost equally in both techniques. The statistical treatment of data indicates that the differences between the methods are within the acceptable range. PMID:18967736

Balasubramanian, S; Pugalenthi, V

1999-10-01

25

Development and Validation of a UV Spectrophotometric Method for the Simultaneous Estimation of Eprosartan Mesylate and Hydrochlorothiazide in Bulk and Formulations.  

PubMed

A simple, efficient, precise and accurate absorbance ratio method have been developed for the estimation of eprosartan mesylate and hydrochlorothiazide in pure and in fixed dose combination. In this method, UV spectra of eprosartan mesylate and hydrochlorothiazide were overlayed which involves the formation of Q-absorbance equation at 249.1 nm (isobestic point) and 274.5 nm, the max of hydrochlorothiazide. Both the drugs obeyed Beers law in the concentration range of 6-36 ?g/ml and 1-10 ?g/ml for eprosartan mesylate and hydrochlorothiazide, respectively. The accuracy of the method was determined by recovery studies and was found to be in the range of 102.29-103.10% and 99.52-101.60% for eprosartan mesylate and hydrochlorothiazide, respectively. The method was validated as per ICH guidelines and statistically. The method showed good reproducibility and recovery with % RSD less than 2. The method was found to be simple, economic, accurate and reproducible and can be used for routine analysis of eprosartan mesylate and hydrochlorothiazide in pure and in fixed dose combinations. PMID:22923871

Anandakumar, K; Santhi, D Vijaya; Jothieswari, D; Subathrai, R; Vetrichelvan, T

2011-09-01

26

Development and Validation of a UV Spectrophotometric Method for the Simultaneous Estimation of Eprosartan Mesylate and Hydrochlorothiazide in Bulk and Formulations  

PubMed Central

A simple, efficient, precise and accurate absorbance ratio method have been developed for the estimation of eprosartan mesylate and hydrochlorothiazide in pure and in fixed dose combination. In this method, UV spectra of eprosartan mesylate and hydrochlorothiazide were overlayed which involves the formation of Q-absorbance equation at 249.1 nm (isobestic point) and 274.5 nm, the max of hydrochlorothiazide. Both the drugs obeyed Beers law in the concentration range of 6-36 ?g/ml and 1-10 ?g/ml for eprosartan mesylate and hydrochlorothiazide, respectively. The accuracy of the method was determined by recovery studies and was found to be in the range of 102.29-103.10% and 99.52-101.60% for eprosartan mesylate and hydrochlorothiazide, respectively. The method was validated as per ICH guidelines and statistically. The method showed good reproducibility and recovery with % RSD less than 2. The method was found to be simple, economic, accurate and reproducible and can be used for routine analysis of eprosartan mesylate and hydrochlorothiazide in pure and in fixed dose combinations.

Anandakumar, K.; Santhi, D. Vijaya; Jothieswari, D.; Subathrai, R.; Vetrichelvan, T.

2011-01-01

27

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; Minh Thi Nguyen, Hue

2014-01-01

28

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

PubMed Central

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

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

2014-01-01

29

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

Microsoft Academic Search

Simple conducting polymer–polyaniline-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 Grzegrzó?ka; Agata Michalska; Krzysztof Maksymiuk

2010-01-01

30

Comparative Study of RP-HPLC and UV Spectrophotometric Techniques for the Simultaneous Determination of Amoxicillin and Cloxacillin in Capsules  

PubMed Central

Reversed-phase HPLC and UV spectrophotometric techniques using water as solvent have been developed and validated for the simultaneous determination of amoxicillin and cloxacillin in capsules. For both techniques, the linearity range of 60.073x2013;140.0 µg/mL was studied. The spectrophotometric data show that non-derivative techniques, such as absorbance ratio and compensation, and ratio spectra first-order derivative could be successfully used for the co-assay of amoxicillin and cloxacillin. Based on the statistical comparison of spectrophotometric and chromatographic data, the interchangeability between HPLC and UV spectrophotometric techniques has been suggested for the routine analysis.

Giang, Do T; Hoang, Vu D

2010-01-01

31

UV Bright-Star Spectrophotometric Supplement (Macau-Hercot+ 1978)  

NASA Astrophysics Data System (ADS)

This catalogue is a supplement of the Ultraviolet Bright Star Spectrophotometric Catalogue (=III/39A). It contains observations carried out by the S2/68 Ultraviolet Sky Survey Telescope (UVSST) aboard the ESRO satellite TD-1. The data presented in this supplement were obtained during the second and third observation periods, which lasted from 19 February 1973 to 30 September 1973 and from 16 February to 6 May 1974. The S2/68 experiment has been described by Boksenberg et al. (=1973MNRAS.163..291B) Owing to the optical scanning mode, most of the stars observed during the first observational period, the spectra of which are included in the "Ultraviolet Bright-Star Spectrophotometric Catalogue", were seen again by the telescope. This supplement, however, has been limited to the spectra of stars that were not observed during the first period. The data reduction and selection criteria are identical to those underlying the main Catalogue and hence the data presented in the Supplement are directly comparable with those in the main Catalogue. The Supplement contains data for 435 stars. For a statistical summary of the observed stars, see the tables I and II in the published version of the Supplement. The spectrum scanning itself was achieved by the movement of a star image across the wide entrance slot of the spectrophotometer, which caused the corresponding spectrum image to pass over the three exit slits in the direction of dispersion. The motion of the primary image during each detector integration interval (0.148 s) was equivalent to 19.4 A, depending on the channel. The wavelength range covered was 1350 - 2550 A. The passband of the photometer channel, defined by a glass transmission filter and the photocathode tube response, was centered at 2740 A and had a full width at half height of 310 A. (1 data file).

Macau-Hercot, D.; Jamar, C.; Monfils, A.; Thompson, L.; Houziaux, L.; Wilson, R.

1995-10-01

32

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

PubMed

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

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

2008-09-01

33

Simple Spectrophotometric Methods for Standardizing Ayurvedic Formulation  

PubMed Central

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

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

2012-01-01

34

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

35

Sensitive Spectrophotometric Method for Determining Methadone in Biologic Specimens.  

National Technical Information Service (NTIS)

The extensive use of methadone for the treatment of opiate addiction increases significantly the need for quantitative determination of methadone in urine and tissues. Existing spectrophotometric methods are limited in sensitivity by the low molar absorpt...

H. E. Hamilton J. E. Wallace J. T. Payte K. Blum

1972-01-01

36

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

PubMed

A simple, sensitive, cost-effective and reproducible UV-spectrophotometric method has been developed and validated for the estimation of disodium edetate in topical gel formulations. Solution of disodium edetate reacts with ferric chloride to form complex in 0.1 N HCl giving ?max at 270 nm. Beer's law was obeyed in the concentration range of 5-50 ?g/mL (r (2)= 0.9997). The limit of detection and limit of quantitation were found to be 1.190 and 3.608 ?g/mL, respectively. The results show that the procedure is accurate, precise, and reproducible (relative standard deviation < 1%), while being simple and less time consuming. The study concluded that the UV-spectrophotometric method could be used for the quantification of disodium edetate in pure form as well as in pharmaceutical formulations. PMID:23781446

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

2011-04-01

37

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

38

Kinetic spectrophotometric methods for determination of trimetazidine dihydrochloride  

Microsoft Academic Search

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

Ibrahim A. Darwish

2005-01-01

39

Four spectrophotometric methods for determination of nitrofurazone in pharmaceutical formulations  

Microsoft Academic Search

Four simple and sensitive visible spectrophotometric methods (A-D) for the determination of nitrofurazone in bulk samples and pharmaceutical formulations are described. They are based on the formation of colored species by treating either its reduction product with 3-methylbenzothiazolin-2-one hydrazone in the presence of ferric chloride (method A: ?max 600 nm) or its hydrolysis product with thiobarbituric acid (method B: ?max

Bhetanabhotla S. Sastry; Jangala V. Rao; Tippanu Thirupathi Rao; Chilukuri S. P. Sastry

1992-01-01

40

Pyrocatechol Violet in spectrophotometric and novel optical methods  

NASA Astrophysics Data System (ADS)

The published data on chemical and analytical characteristics and the use of binary and ternary Pyrocatechol Violet complexes in spectrophotometric and novel optical methods of analysis are generalised. New promising trends are considered including studies of chromaticity characteristics of complexes of this reagent with various metal ions formed in the presence of cationic surfactants on the surface of anion-exchange resins or neutral sorbents aimed at increasing the sensitivity of determinations and developing new, more efficient test scales and optical sensors.

Ivanov, Vadim M.; Kochelayeva, Galina A.

2006-03-01

41

Determination of berkelium by the method of spectrophotometric titration  

Microsoft Academic Search

The method that the authors propose consists of the following: berkelium is oxidized electrochemically, spectrophotometric titration of berkelium(IV) by a solution of the reducing agent is performed, and the amount of berkelium(IV) is determined according to the volume of the titrant, and considering the degree of oxidation of berkelium(III) to berkelium(IV), the total berkelium content in the sample is also

L. M. Frolova; V. M. Vityutnev; V. M. Vasilev

1987-01-01

42

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

PubMed

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

Singh, D K; Verma, Rohan

2007-10-01

43

Visible spectrophotometric method for the determination of aripiprazole in tablets.  

PubMed

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

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

2011-01-01

44

Visible Spectrophotometric Method for the Determination of Aripiprazole in Tablets  

PubMed Central

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

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

2011-01-01

45

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

PubMed Central

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

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

2011-01-01

46

Simple and sensitive spectrophotometric methods for determination of amantadine hydrochloride  

NASA Astrophysics Data System (ADS)

Three simple and sensitive spectrophotometric methods (A-C) for determination of amantadine hydro-chloride have been developed and validated. The first method (A) is based on the oxidation of the drug by ammonium molybdate. The second method (B) was based on the charge-transfer complexation reaction between the amantadine base as an electron donor and iodine as a ?-acceptor. The third method (C) is based on the reaction of N-alkylvinylamine formed from the interaction of the free amino group in amantadine molecule and acetalde-hyde with chloranil to give colored vinylamino-substituted benzoquinone. The colored products of these reactions were measured at their corresponding maximum absorption peaks. Different variables affecting the reactions were carefully studied and optimized. Under the optimum conditions, linear relationships with good correlation coefficients 0.9993-0.9998 were found between the reading and the corresponding concentration of the drug in the range 2-90 µg·ml-1. The limits of detection ranged from 0.16 to 1.91 µg·ml-1. The precision of the methods was satisfactory: the values of relative standard deviation did not exceed 1.63%. The proposed methods were successfully applied to the analysis of amantadine HCl in its capsules with good accuracy and precision; the label claim percentages ranged from 99.8 to 100.5 ± (0.52-1.22) %. The results obtained by the proposed spectrophotometric methods were comparable with those obtained by the official method.

Darwish, I. A.; Khedr, A. S.; Askal, H. F.; Mahmoud, R. M.

2006-11-01

47

Spectrophotometric and spectrofluorimetric methods for determination of Racecadotril.  

PubMed

Two accurate and sensitive spectrophotometric and spectrofluorimetric methods were developed for determination of Racecadotril. In the first method reduction of Fe3+ into Fe2+ in presence of o-phenanthroline by Racecadotril to form a stable orange-red ferroin chelate [Fe-(Phen)3]2+ was the basis for its determination. The absorbance at 510 nm was measured and linear correlation was obtained in the concentration range of 2.5-25 µg mL(-1). In the second method the native fluorescence of Racecadotril in acetonitrile solvent at ?=319 nm when excitation was at 252 nm is used for its determination. Linear correlation was obtained in the concentration range of 50 to 500 ng mL(-1). The proposed methods were applied for determination of Racecadotril in bulk powder with mean accuracy of 100.39±1.239 for the spectrophotometric method and 100.09±1.042 for the spectrofluorimetric method. The proposed methods were successfully applied for determination of Racecadotril in its pharmaceutical dosage form. PMID:21190913

Ali, Nouruddin Wageih; Elghobashy, Mohammed Refaat; Mahmoud, Mohammed Gamal; Mohammed, Mohammed Abdelkawy

2011-01-01

48

A spectrophotometric method for the determination of hydroperoxides in liposomes  

NASA Astrophysics Data System (ADS)

A modification of the Asakawa-Matsushita iodometric assay method for the determination of the content of lipid hydroperoxides was developed which permits the simultaneous processing of many samples of high lipid content. The method has the advantages of simplicity as well as good reproducibility, so it is not necessary to process standards with each determination. Our technique exceeds the sensitivity attained with other spectrophotometric determinations reported in the literature. The method requires the total elimination of water from the samples, and this was accomplished using an azeotropic mixture of ethanol:water of 96:4. The results obtained with liposomes indicate that the method is applicable to biological material limited to small volume samples, ranging 5-50 ?l. We want to emphasize that this method permits the study of the peroxidation process as function of time.

Cimato, A.; Facorro, G.; Aguirre, F.; Hager, A.; De Paoli, T.; Ihlo, J.; Farach, H. A.; Poole, C. P., Jr.

1998-10-01

49

Spectrophotometric method for determination parts per million levels of cyclohexylamine in water.  

PubMed

UV-vis spectrophotometric method for the analysis of cyclohexylamine (CHA) in aqueous medium in the range of 0.3-20 ppm was developed by coupling CHA with sodium 1,2-naphthaquinone-4-sulphonate (NQS). At 470 nm a calibration slope of 0.028 OD ppm(-1) was observed. Minimum detection limit was 0.3 ppm with standard deviation of 0.1 ppm. Reagent concentration and solution pH for the analysis are optimised by studying its effect on absorbance at 470 nm. The method was applied to analyse CHA for evaluating the performance of ion exchange resin used in condensate purification plant (CPP) of power station where, CHA is used as all volatile treatment (AVT) reagent to inhibit steam generator (SG) corrosion. Structure of the adduct formed by coupling CHA with NQS is elucidated using NMR ((1)H and (13)C) and IR spectra, CHN analysis and mole ratio variation method. PMID:18967343

Kumbhar, A G; Narasimhan, S V; Mathur, P K

1998-10-01

50

A Novel Spectrophotometric Method for the Determination Oxacillin Sodium  

PubMed Central

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

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

2009-01-01

51

Extractive Spectrophotometric Method for the Determination of Tropicamide  

PubMed Central

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

Shoaibi, ZA; Gouda, AA

2012-01-01

52

Simultaneous UV-spectrophotometric determination of CS 2 and COS using the piperidine, pyrrolidine, ethylenediamine or morpholine reagent  

Microsoft Academic Search

The success of a spectrophotometric method for the determination of dithiocarbamate or tetramethylthiuram disulphide (thiram) fungicide residues based on the quantification of the evolved CS2 after an acid hydrolysis of the fungicide depends on the sensitivity and selectivity of the CS2 absorbing reagent. In the present study piperidine, pyrrolidine, ethylenediamine and morpholine and their corresponding optimum reaction conditions with CS2

Wolfgang Schwack; Steven Nyanzi

1993-01-01

53

Spectrophotometric estimation of tamsulosin hydrochloride by acid-dye method  

PubMed Central

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

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

2011-01-01

54

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

55

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

56

A spectrophotometric readout method for free radical dosimetry  

NASA Astrophysics Data System (ADS)

An accurate and inexpensive spectrophotometric readout method is given for free radical dosimetry. The stable free radicals in irradiated alanine/glutamine powder, when dissolved in a solution containing ferrous ammonium sulphate and xylenol orange in 0.05 N H 2SO 4(FX), oxidize ferrous ions and the xylenol orange forms a complex with ferric ions produced in the solution. The absorbance of the complex is measured at 525 nm for alanine and at 540 nm for glutamine. The influence of various parameters, such as size of the container, weight of the powder dissolved, xylenol orange concentration, purity of distilled water, postirradiation stability and dose-rate dependence on the response of the dosimetric technique, has been investigated. It was found that the dosimetric response is independent of dose-rate. Alanine does not show any significant postirradiation fading. Irradiated glutamine powder is stable for about a month, the fading is less than 2% up to three months later, and it increases to only about 5% over a period of six months. The reproducibility of the method is better than ±2%, and it offers an alternative to ESR and lyoluminescence techniques for free radical dosimetry. A dose of 0.01 to 4 kGy can be measured with an alanine dosimeter and 0.1 to 100 kGy with a glutamine dosimeter. Empirical relationships between absorbance and dose are given.

Gupta, B. L.; Bhat, R. M.; Narayan, G. R.; Nilekani, S. R.

57

Determination of berkelium by the method of spectrophotometric titration  

SciTech Connect

The method that the authors propose consists of the following: berkelium is oxidized electrochemically, spectrophotometric titration of berkelium(IV) by a solution of the reducing agent is performed, and the amount of berkelium(IV) is determined according to the volume of the titrant, and considering the degree of oxidation of berkelium(III) to berkelium(IV), the total berkelium content in the sample is also determined. In this case the necessity for preliminary determination of the molar extinction coefficient of berkelium(IV) under the experimental conditions falls away. Moreover, the radiometric method of determining the berkelium content is not used. Successful titration requires selection of a reagent which, on the one hand, would rapidly reduce berkelium(VI), but on the other hand, neither itself nor the reaction products would interfere with the measurement of the optical density of berkelium(IV). As is well known, berkelium(IV) is quantitatively and rapidly reduced by hydrogen peroxide (10, 11), hydroxylamine (11), and nitrous acid (9). After preliminary experiments, they selected hydrogen peroxide and sodium nitrite as the titrants.

Frolova, L.M.; Vityutnev, V.M.; Vasil'ev, V.M.

1987-01-01

58

Analysis of Lactulose Preparations by Spectrophotometric and High Performance Liquid Chromatographic Methods  

Microsoft Academic Search

Spectrophotometric methods of analy- sis were applied to sugar mixtures pro- duced during isomerization of lactose to lactulose. A combination of four estab- lished spectrophotometric methods was used to quantitate galactose, tagatose, lactose, and lactulose, the four major sugars present. In addition, a method originally developed for determining lactose with methylamine at 65°C and pH 12.7 was suitable for combined

F. W. Parrish; K. Hicks; L. Doner

1980-01-01

59

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

60

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

61

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

62

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 Ĺ 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 Ĺ and 1600 Ĺ) 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 Ĺ. 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 Ĺ. 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 Ĺ chromospheric line is a good indicator of Ellerman bombs and can bring new information about these phenomena.

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

2007-10-01

63

Langley method of calibrating UV filter radiometers  

Microsoft Academic Search

The Langley method of calibrating UV multifilter shadow band radiometers (UV-MFRSR) is explored in this paper. This method has several advantages over the traditional standard lamp calibrations: the Sun is a free, universally available, and very constant source, and nearly continual automated field calibrations can be made. Although 20 or so Langley events are required for an accurate calibration, the

James Slusser; James Gibson; David Bigelow; Donald Kolinski; Patrick Disterhoft; Kathleen Lantz; Arthur Beaubien

2000-01-01

64

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

PubMed

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

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

2012-10-01

65

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

PubMed

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

Yoshida, M; Watabiki, T; Ishida, N

1989-12-01

66

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

NASA Astrophysics Data System (ADS)

A sensitive, simple and rapid spectrophotometric method was developed for the determination of diphenhydramine in pharmaceutical preparation. The method was based on the charge-transfer complex of the drug, as n-electron donor, with 2,3-dichloro-5,6-dicyano- p-benzoquinone (DDQ), as ?-acceptor. The formation of this complex was also confirmed by UV-vis, FTIR and 1H NMR spectra techniques and thermal analysis. The proposed method was validated according to the ICH guidelines with respect to linearity, limit of detection, limit of quantification, accuracy, precision, recovery and robustness. The linearity range for concentrations of diphenhydramine was found to be 12.5-150 ?g/mL with acceptable correlation coefficients. The detection and quantification limits were found to be 2.09 and 6.27 ?g/mL, respectively. The proposed and references methods were applied to the determination of drug in syrup. This preparation were also analyzed with an reference method and statistical comparison by t- and F-tests revealed that there was no significant difference between the results of the two methods with respect to mean values and standard deviations at the 95% confidence level.

Ulu, Sevgi Tatar; Elmali, Fikriye Tuncel

2010-09-01

67

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

PubMed

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

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

2012-03-01

68

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

PubMed Central

Ultraviolet (UV), first derivative, second derivative, and AUC-spectrophotometric methods for the determination of letrozole in pharmaceutical formulations have been developed. For UV-spectrophotometry, the standard solutions were measured at 240.0 nm. The linearity ranges were found to be 0.25–20.0 ?gml–1 in methanol and the regression equation was A=1.20×10–1C+2.22×10–2(r2=0.9994). For the first derivative spectrophotometry, the response (dA/d?) of standard solutions was measured at 224.0 nm. The calibration curve was constructed by plotting dA/d? values against concentrations 0.25–20.0 ?gml–1, of letrozole. The regression equation of the linear calibration graph was calculated as D1=3.89×10–3C+1.85×10–4(r2=0.9987). For the second derivative spectrophotometry, the response (d2A/d?2) of standard solutions was measured at 241.0 nm. The calibration curve was constructed by plotting d2A/d?2 values against concentrations 0.5–20.0 ?gml–1 of letrozole standards in methanol. The regression equation of the linear calibration graph was calculated as D2=-1.59×10–3C-4.66×10–4(r2=0.9985). The AUC-spectrophotometric method was based on the calculation of Area under Curve (AUC), for analysis of letrozole in the wavelength range of 235.0–245.0 nm. The calibration curve was constructed by plotting AUC values against concentrations 0.25–20.0 ?gml–1, of letrozole. The regression equation of the linear calibration graph was calculated as AUC=1.132C+0.2153 (r2=0.9994). The methods were validated by following the analytical performance parameters suggested by the International Conference on Harmonization (ICH). All validation parameters were within the acceptable range. The developed methods were successfully applied to estimate the amount of letrozole in pharmaceutical formulations.

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

2010-01-01

69

A spectrophotometric method for the determination of 5-phosphoribosyl-1-pyrophosphate.  

PubMed

A new, sensitive, specific and simple spectrophotometric method for the determination of 5-phosphoribosyl-l-pyrophosphate (PRPP) is presented. PRPP is reacted with excess hypoxanthine in the presence of hypoxanthine-guanine phosphoribosyltransferase. At the end of the reaction, PRPP concentration is measured from the extent of conversion of hypoxanthine to inositate. The concentration of the purine base is determined spectrophotometrically in the presence of xanthine oxidase. PMID:477861

Salerno, C; Giacomello, A; Messina, E

1979-08-15

70

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

Microsoft Academic Search

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

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

1952-01-01

71

A new spectrophotometric method for the rapid assessment of deep frying oil quality  

Microsoft Academic Search

A new and quick spectrophotometric method was developed to assess deep-frying oil quality. The scanned spectrophotometric\\u000a curves of the frying oil samples from 350 and 650 nm wavelength changed systematically with the duration of deep frying. The\\u000a absorbances of the frying oil samples, especially those measured at 490 nm, increased significantly during frying and were\\u000a significantly correlated to frying time

Xin-Qing Xu

2000-01-01

72

Development and validation of RP-HPLC and ultraviolet spectrophotometric methods of analysis for the quantitative estimation of antiretroviral drugs in pharmaceutical dosage forms.  

PubMed

A high-performance liquid chromatographic and an UV spectrophotometric method were developed and validated for the quantitative determination of three antiretroviral drugs viz. Lamivudine, Stavudine and Nevirapine that constitute one of the first line regimens in antiretroviral therapy. The different analytical performance parameters such as linearity, precision, accuracy, specificity, limit of detection (LOD) and limit of quantification (LOQ) were determined according to International Conference on Harmonization ICH Q2B guidelines. Chromatography was carried out by isocratic technique on a reversed-phase C-18 SYMMETRY column with mobile phase based and optimized depending on the polarity of the molecules. The UV spectrophotometric determinations were performed at 270, 265 and 313 nm for Lamivudine, Stavudine and Nevirapine, respectively. The linearity of the calibration curves for each analyte in the desired concentration range is good (r(2)>0.999) by both the HPLC and UV methods. Both the methods were accurate and precise with recoveries in the range of 97 and 103% for all the three drugs and relative standard deviation (R.S.D.) <5%. Moreover, the accuracy and precision obtained with HPLC correlated well with the UV method which implied that UV spectroscopy can be a cheap, reliable and less time consuming alternative for chromatographic analysis. The proposed methods are highly sensitive, precise and accurate and hence were successfully applied for the reliable quantification of API content in the commercial formulations of Lamivudine, Stavudine and Nevirapine. PMID:16330261

Sarkar, Mahua; Khandavilli, Sateesh; Panchagnula, Ramesh

2006-01-18

73

Spectrophotometric analysis of molecular transport in gels  

Microsoft Academic Search

An automated spectrophotometric method has been developed for analyzing molecular transport out from and into gels. A Beckman DU7500 diode-array UV-visible spectrophotometer with gel scanner was modified to accept and longitudinally scan a quartz diffusion cell, 0.3×10×40 mm. Molecules of interest are identified and concentrations quantitated via analysis of spectrophotometric absorbance peaks relative to background absorbance of the gel. Thus,

Erik N. Dunmire; Audra M. Plenys; David F. Katz

1999-01-01

74

Spectrophotometric and spectrofluorimetric methods for the determination of tranexamic acid in pharmaceutical formulation.  

PubMed

Two simple and sensitive spectrophotometric and fluorimetric methods for the determination of tranexamic acid in tablets are developed. The methods are based on condensation the primary amino group of tranexamic acid with acetyl acetone and formaldehyde producing a yellow coloured product, which is measured spectrophotometrically at 335 nm or fluorimetrically at 480 nm the colour was stable for at least 1 h. Beer's law was valid within a concentration rang of 0.05-2.0 microg ml-1 spectrophotometrically and 0.05-0.25 microg ml-1 fluorimetrically. All the variables were studied to optimize the reaction conditions. No interference was observed in the presence of common pharmaceutical excipints. The validity of both methods was tested by analyzing tranexamic acid in its pharmaceutical preparations. Good recoveries were obtained and the results were comparable with those obtained by standard method. PMID:17329872

El-Aroud, Khalifa Abulghasem; Abushoffa, Adel Mohamed; Abdellatef, Hisham Ezzat

2007-03-01

75

Spectrophotometric Methods for Quantifying Pigmentation in Human Hair—Influence of MC1R Genotype and Environment  

Microsoft Academic Search

Eumelanin (brown ? black melanin) and pheomelanin (red ? yellow melanin) in human hair can be quantified using chemical methods or approximated using spectrophotometric methods. Chemical methods consume greater resources, making them less attractive for epidemiological studies. This investigation sought to identify the spectrophotometric measures that best explain the light-dark continuum of hair color and the measure that is best

Sri N. Shekar; David L. Duffy; Tony Frudakis; Grant W. Montgomery; Michael R. James; Richard A. Sturm; Nicholas G. Martin

2008-01-01

76

Synergistic enhancement effect of room temperature ionic liquids for cloud point extraction combined with UV-vis spectrophotometric determination nickel in environmental samples  

NASA Astrophysics Data System (ADS)

A new method based on enhancement effect of room temperature ionic liquids for cloud point extraction trace amounts of nickel combined with UV-vis spectrophotometric determination was developed. Room temperature ionic liquids (RTILs) and diethyldithiocarbamate (DDTC) were used enhancement reagent and chelating reagent, respectively. The addition of room temperature ionic liquids leads to 3.0 times improvement in the determination of nickel. The nonionic surfactant Triton X-100 was used as the extractant. When the temperature of the system was higher than the cloud point of Triton X-100, Ni-DTC complex was extracted into Triton X-100 and separation of the analyte from the matrix was achieved. Some parameters that influenced cloud point extraction and subsequent determination were evaluated in detail, such as the concentrations of RTILs, DDTC and Triton X-100; pH of sample solution, as well as interferences. Under optimized conditions, an enrichment factor of 72 could be obtained, and the detection limit (LOD) for Ni was 0.5 ng mL-1. Relative standard deviations for five replicate determinations of the standard solution containing 50 ng mL-1 Ni was 3.9%. The proposed method was successfully applied to the determination of nickel in certified reference materials with satisfactory results.

Zeng, Chujie; Xu, Xili; Zhou, Neng; Lin, Yao

77

Synergistic enhancement effect of room temperature ionic liquids for cloud point extraction combined with UV-vis spectrophotometric determination nickel in environmental samples.  

PubMed

A new method based on enhancement effect of room temperature ionic liquids for cloud point extraction trace amounts of nickel combined with UV-vis spectrophotometric determination was developed. Room temperature ionic liquids (RTILs) and diethyldithiocarbamate (DDTC) were used enhancement reagent and chelating reagent, respectively. The addition of room temperature ionic liquids leads to 3.0 times improvement in the determination of nickel. The nonionic surfactant Triton X-100 was used as the extractant. When the temperature of the system was higher than the cloud point of Triton X-100, Ni-DTC complex was extracted into Triton X-100 and separation of the analyte from the matrix was achieved. Some parameters that influenced cloud point extraction and subsequent determination were evaluated in detail, such as the concentrations of RTILs, DDTC and Triton X-100; pH of sample solution, as well as interferences. Under optimized conditions, an enrichment factor of 72 could be obtained, and the detection limit (LOD) for Ni was 0.5ng mL(-1). Relative standard deviations for five replicate determinations of the standard solution containing 50ng mL(-1) Ni was 3.9%. The proposed method was successfully applied to the determination of nickel in certified reference materials with satisfactory results. PMID:22503873

Zeng, Chujie; Xu, Xili; Zhou, Neng; Lin, Yao

2012-08-01

78

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

79

An Improved Spectrophotometric Method To Study the Transport, Attachment, and Breakthrough of Bacteria through Porous Media  

PubMed Central

This study reports an improved spectrophotometric method for studying bacterial (Pseudomonas fluorescens UPER-1) transport and attachment in saturated porous media (silica sand). While studying the effect of ionic strength by the traditional packed-column spectrophotometric method, we encountered an artifact. The absorbance of a well-stirred bacterial suspension was found to decrease with time in the presence of high concentrations of sodium and potassium phosphate salts (?10?2 M) as the cells continued to age in a resting stage. Our results show that collision efficiency and a bed ripening index will be in error by as much as 20% if breakthrough is measured by the traditional spectrophotometric technique. We present an improved experimental technique that will minimize the artifact and should substantially advance the understanding of bacteria transport in porous media.

Deshpande, P. A.; Shonnard, D. R.

2000-01-01

80

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

81

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

82

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

83

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

PubMed

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

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

2014-05-21

84

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

85

New Spectrophotometric Method for Determination of Dissolved Proteins in Low Concentration Range.  

National Technical Information Service (NTIS)

The objective of this research was to introduce a new spectrophotometric method for determination of dissolved proteins in the 10-2500 mg/l range using carbonate-tartrate reagent phosphomolybdic-phosphotungstic reagent, and copper sulfate. The new analyti...

L. K. Wang A. E. Thayer

1983-01-01

86

Measurement of peroxisomal enzyme activities in the liver of brown trout (Salmo trutta), using spectrophotometric methods  

Microsoft Academic Search

BACKGROUND: This study was aimed primarily at testing in the liver of brown trout (Salmo trutta) spectrophotometric methods previously used to measure the activities of catalase and hydrogen peroxide producing oxidases in mammals. To evaluate the influence of temperature on the activities of those peroxisomal enzymes was the second objective. A third goal of this work was the study of

Maria Joăo Rocha; Eduardo Rocha; Albina D Resende; Alexandre Lobo-da-Cunha

2003-01-01

87

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

88

Development and Validation of Spectrophotometric Methods for the Estimation of Mesalamine in Tablet Dosage Forms  

PubMed Central

Three simple and sensitive visible spectrophotometric methods (A, B, and C) have been developed for the quantitative estimation of mesalamine in bulk drug and pharmaceutical dosage forms. Methods were based on the formation of colored chromogens, which were measured at 552 nm, 440 nm, and 494 nm, respectively. The results obtained with the proposed methods were found to be unsatisfactory with the labeled amounts when the tablet dosage forms were analyzed.

Patel, KM; Patel, CN; Panigrahi, B; Parikh, AS; Patel, HN

2010-01-01

89

AAS and spectrophotometric methods for the determination metoprolol tartrate in tablets  

NASA Astrophysics Data System (ADS)

Sensitive and specific atomic adsorption spectroscopy (AAS) and spectrophotometric methods have been developed for the determination of beta adrenergic blocking drug, metoprolol tartrate.The method is based on the formation of Cu(II) dithiocarbamate complex by derivatization of the secondary amino group of metoprolol with CS 2 and CuCl 2 in the presence of ammonia.The copper-bis(dithiocarbamate) complex was extracted into chloroform and the concentration of metoprolol tartrate was determined directly by spectrophotometric and indirectly by AAS measurement of copper.The two methods developed were applied to the assay of metoprolol tartrate in commercial tablet formulations.The methods were compared statistically with each other and with the high performance liquid chromatography (HPLC) method of USPXXII using t- and F-tests.

Alpdo?an, Güzin; Sungur, Sidika

1999-11-01

90

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

Microsoft Academic Search

High-performance liquid chromatography (HPLC) and multivariate spectrophotometric methods are described for the simultaneous determination of ambroxol hydrochloride (AM) and doxycycline (DX) in combined pharmaceutical capsules. The chromatographic separation was achieved on reversed-phase C18 analytical column with a mobile phase consisting of a mixture of 20mM potassium dihydrogen phosphate, pH 6–acetonitrile in ratio of (1:1, v\\/v) and UV detection at 245nm.

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

2008-01-01

91

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

92

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

PubMed

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 degrees 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 microg ml(-1) for tramadol, dothiepin and 5-25 microg ml(-1) for acebutolol. Using the spectrofluorimetric method linearity ranged from 0.25 to 1.25 microg ml(-1) for tramadol, dothiepin and 1-5 microg 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. PMID:16716651

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

2006-12-01

93

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

94

Trace determination and chemical speciation of selenium in environmental water samples using catalytic kinetic spectrophotometric method  

Microsoft Academic Search

A catalytic kinetic method is described for the determination of Se(IV), Se(VI) and total inorganic selenium in water based on the catalytic effect of Se(IV) on the reduction of bromate by hydrazine dihydrochloride in acidic media. The generated bromine decolorized methyl orange (MO) and the reaction was monitored spectrophotometrically at 507nm as a function of time. The initial rate and

Vimlesh Chand; Surendra Prasad

2009-01-01

95

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

Microsoft Academic Search

A sensitive spectrophotometric method based on the evolution of CS2 and colour development by leuco crystal violet is described for the determination of dithiocarbamate fungicides, e.g. thiram, ziram and zineb. Dithiocarbamate fungicides release CS2 on acid hydrolysis. This CS2 is absorbed in ethanolic sodium hydroxide and forms xanthate. The xanthate formed is subsequently treated with potassium iodate and N-chlorosuccinimide, during

Ritu Kesari; V. K. Gupta

1998-01-01

96

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.

Önal, Arma?an; Sagirli, Olcay

2009-02-01

97

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

PubMed

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

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

2008-08-01

98

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

NASA Astrophysics Data System (ADS)

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

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

2008-08-01

99

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

100

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

101

Spectrophotometric Analysis of Boron in Steels Using the Diantrimide Method.  

National Technical Information Service (NTIS)

The trials carried out by the Analytical Laboratory of Acos Finos Piratini, in order to choose a rapid and precise method for the boron determination on carbon and stainless steel are presented. Three photometric methods were experimented: The first one, ...

R. A. Villanova E. S. Silveira N. B. Bonatto

1980-01-01

102

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

2012-01-01

103

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

PubMed Central

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

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

2012-01-01

104

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.

105

Extractive spectrophotometric method for the determination of atmospheric nitrogen dioxide  

NASA Astrophysics Data System (ADS)

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

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

106

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

107

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 µg/ml with correlation coefficient 0.9999. The method was found to be precise, accurate, specific, and validated as per ICH guidelines and can be used for determination of Escitalopram Oxalate in tablet formulations. PMID:21264107

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

2010-10-01

108

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

PubMed Central

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

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

2010-01-01

109

Determination of niobium in rocks by an isotope dilution spectrophotometric method  

USGS Publications Warehouse

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

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

1970-01-01

110

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

111

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

PubMed

One titrimetric and two spectrophotometric methods are described for the determination of ketotifen fumarate (KTF) in bulk drug and in tablets using cerium(IV) as the oxidimetric agent. In titrimetry (method A), the drug was treated with a measured excess of cerium(IV) in H2SO4 medium and after a standing time of 10 min, the surplus oxidant was determined by back titration with iron(II). The spectrophotometric procedures involve addition of a known excess of cerium(IV) to KTF in acid medium followed by the determination of unreacted oxidant by reacting with either p-dimethyl amino benzaldehyde and measuring the resulting colour at 460?nm (method B) or o-dianisidine and subsequent measurement of the absorbance of coloured product at 470?nm (method C). Titrimetric assay is based on a 1?:?2 reaction stoichiometry between KTF and cerium(IV) and the method is applicable over 2-18?mg range. In spectrophotometry, regression analysis of Beer's law plots showed a good correlation in 0.4-8.0 and 0.4-10.0?g?mL(-1) KTF ranges for method B and method C, respectively, and the corresponding molar absorptivity coefficients are calculated to be 4.0 × 10(4) and 3.7 × 10(4)?L?mol(-1)?cm(-1). PMID:24324496

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

2013-01-01

112

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

PubMed Central

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

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

2013-01-01

113

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

PubMed

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

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

2008-09-15

114

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.

2011-01-01

115

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

PubMed

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

Khalifa, M E; Hafez, M A

1998-11-01

116

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

PubMed

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. PMID:24887506

Fayez, Yasmin Mohammed

2014-11-11

117

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

NASA Astrophysics Data System (ADS)

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

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

2010-02-01

118

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

PubMed Central

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

2012-01-01

119

Orthogonal signal correction-partial least squares method for simultaneous spectrophotometric determination of cypermethrin and tetramethrin  

NASA Astrophysics Data System (ADS)

The simultaneous determination of cypermethrin and tetramethrin mixtures by using spectrophotometric method is a difficult problem in analytical chemistry, due to spectral interferences. By multivariate calibration methods, such as partial least squares (PLS) regression, it is possible to obtain a model adjusted to the concentration values of the mixtures used in the calibration range. Orthogonal signal correction (OSC) is a preprocessing technique used for removing the information unrelated to the target variables based on constrained principal component analysis. OSC is a suitable preprocessing method for partial least squares calibration of mixtures without loss of prediction capacity using spectrophotometric method. In this study, the calibration model is based on absorption spectra in the 200-350 nm range for 25 different mixtures of cypermethrin and tetramethrin. Calibration matrices were containing 0.1-12.9 and 0.1-13.8 ?g mL -1 for cypermethrin and tetramethrin, respectively. The RMSEP for cypermethrin and tetramethrin with OSC and without OSC were 0.0884, 0.0614 and 0.2915, 0.2309, respectively. This procedure allows the simultaneous determination of cypermethrin and tetramethrin in synthetic and real samples good reliability of the determination was proved.

Niazi, Ali; Goodarzi, Mohammad

2008-04-01

120

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

PubMed Central

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

Abdellaziz, Lobna M.; Hosny, Mervat M.

2011-01-01

121

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

122

Analysis of some antifungal drugs by spectrophotometric and spectrofluorimetric methods in different pharmaceutical dosage forms.  

PubMed

Simple spectrophotometric and spectrofluorimetric methods are suggested for the determination of antifungal drugs; clotrimazole, econazole nitrate, ketoconazole, miconazole and tolnaftate. Spectrophotometric one depends on the interaction between imidazole antifungal drugs as n-electron donor with the pi acceptor 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) in methanol or with p-chloranilic acid (p-CA) in acetonitrile. The produced chromogens obey Beer's law at lambda(max) 460, and 520 nm in the concentration range 22.5-200 and 7.9-280 microg ml(-1) for DDQ, and p-CA, respectively. Spectrofluorimetric method is based on the measurement of the native fluorescence of ketoconazole at 375 nm with excitation at 288 nm and or the induced fluorescence after alkaline hydrolysis of tolnaftate with 5 M NaOH solution at 420 nm with excitation at 344 nm. Fluorescence intensity versus concentration is linear for ketoconazole at 49.7-800 ng ml(-1) while for tolnaftate, it is in the range of 20.4-400 ng ml(-1). The proposed methods were applied successfully for the determination of all the studied drugs in their pharmaceutical formulations. PMID:10719920

Khashaba, P Y; El-Shabouri, S R; Emara, K M; Mohamed, A M

2000-03-01

123

Room temperature solution studies of complexation between o-chloranil and a series of anilines by spectrophotometric method.  

PubMed

Electron donor-acceptor (EDA) complex formation between o-chloranil and a series of anilines has been studied in CCl4 medium. In all the cases, EDA complexes are formed instantaneously on mixing the donor and acceptor solutions. N,N-dimethylaniline and N,N-dimethyl-p-toluidine form stable EDA complexes with o-chloranil while the other complexes decay slowly into secondary products. The kinetics of all these reactions has been studied by UV-VIS absorption spectrophotometric method and the rate constants of the reactions and formation constants of the EDA complexes have been determined. The charge transfer (CT) transition energies of the complexes are found to change systematically with change in the number and position of the methyl groups in the donor molecules (methylanilines). From an analysis of this variation, the electron affinity of o-chloranil has been found to be 2.54 eV. A perturbational inductive effect Hückel parameter hMe has been found from this trend and the value obtained (-0.27) is very close to that (-0.3) obtained by Lepley (J. Am. Chem. Soc., 86 (1964) 2545) from a study of tetracyano ethylene (TCNE)-methylbenzene complexes. PMID:11767835

Bhattacharya, S; Banerjee, M; Mukherjee, A K

2001-10-01

124

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

125

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

126

New spectrophotometric method for the determination of some drugs with iodine and wool fast blue BL.  

PubMed

A simple, sensitive and selective method is proposed for the spectrophotometric determination of drugs, viz. ampicillin, penicillin V, amoxycillin, cloxacillin, cefadroxil, ceftezoxime, griseofulvin, streptomycin, nicoumalone and acebutolol HCl, based on their reactivity with iodine. The method involves the addition of excess iodine of known concentration to the drug in the presence of NaOH and the unreacted iodine is determined by the measurement of the decrease in the absorbance of the dye wool fast blue BL (lambda(max)=540 nm) which was found to be the most suitable of several dyes tested. This method was applied for the determination of drug contents in pharmaceutical formulations and enabled the determination of the drugs in microgram quantities (0.8-9.6 mug ml(-1)). No interferences were observed from excipients and the validity of the method was tested against reference methods. PMID:18967115

Sastry, C S; Rao, S G; Y Naidu, P; Srinivas, K R

1998-04-01

127

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

PubMed

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 (PLS-1) and principal component regression (PCR) applied to UV absorption spectra of the two mixtures. In addition HPLC method was developed using a RP 18 column at ambient temperature with mobile phase consisting of acetonitrile-0.05 M potassium dihydrogen phosphate, pH 4.3 (60:40, v/v), with UV detection at 243 nm for mixture 1, and mobile phase consisting of acetonitrile-0.05 M potassium dihydrogen phosphate, pH 3 (50:50, v/v), with UV detection at 245 nm for mixture 2. The methods were validated in terms of accuracy, specificity, precision and linearity in the range of 20-60 microg ml(-1) for GU, 1-3 microg ml(-1) for SL, 20-80 microg ml(-1) for AC, 0.2-1.8 microgml(-1) for PP and 1-5 microg ml(-1) for BX and MP. The proposed methods were successfully applied for the determination of the two multicomponent combinations in laboratory prepared mixtures and commercial syrups. PMID:17046190

El-Gindy, Alaa; Emara, Samy; Shaaban, Heba

2007-02-19

128

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

Microsoft Academic Search

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

129

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

SciTech Connect

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

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

1986-05-01

130

Derivative spectrophotometric method for simultaneous determination of clindamycin phosphate and tretinoin in pharmaceutical dosage forms  

PubMed Central

A derivative spectrophotometric method was proposed for the simultaneous determination of clindamycin and tretinoin in pharmaceutical dosage forms. The measurement was achieved using the first and second derivative signals of clindamycin at (1D) 251 nm and (2D) 239 nm and tretinoin at (1D) 364 nm and (2D) 387 nm. The proposed method showed excellent linearity at both first and second derivative order in the range of 60–1200 and 1.25–25 ?g/ml for clindamycin phosphate and tretinoin respectively. The within-day and between-day precision and accuracy was in acceptable range (CV<3.81%, error<3.20%). Good agreement between the found and added concentrations indicates successful application of the proposed method for simultaneous determination of clindamycin and tretinoin in synthetic mixtures and pharmaceutical dosage form.

2013-01-01

131

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

132

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

133

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

PubMed

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

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

2011-10-15

134

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

NASA Astrophysics Data System (ADS)

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

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

2011-10-01

135

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

136

Spectrophotometric Methods for the Determination of Cefprozil in Bulk and Dosage Form  

PubMed Central

Two simple spectrophotometric methods were developed for the determination of cefprozil in pure bulk and in tablets forms. The first is a colorimetric method based on the coupling of cefprozil, after being hydrolyzed by sodium hydroxide (0.1N), with ascorbic acid as a chromogen (method A). It has been established that cefprozil reacts with ascorbic acid to form a 1:1 water soluble colored product with maximum absorbance (?max) at 408 nm and molar absorptivity of 7.2 × 103L mol?1 cm?1. The second method (Method B) utilizes a direct reaction between cefprozil and sodium hydroxide (1N). A colored product with ?max at 486 nm and molar absorptivity of 7.4 × 103 L mol?1 cm?1 is formed after heating cefprozil with sodium hydroxide (1N). The absorbance-concentration plot was rectilinear over the range 5–25 µg/ml in both methods with correlation coefficient values not less than 0.999. The detection limits (L.O.D.) were 0.96 µg/ml and 0.93 µg/ml for method A and method B respectively. The methods were validated using the USP liquid chromatography method for cefprozil assay. The results obtained by the USP liquid chromatography method for the tablets dosage form were statistically compared with those of the developed methods and evaluated at 95% confidence limits.

Gadkariem, Elrasheed A.; Mutasim, Mohammed M.; Ibrahim, Kamal E. E.; El-Obeid, Humeida A.

2009-01-01

137

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 10–60 ?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.

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

2011-01-01

138

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

PubMed

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

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

2013-01-01

139

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

PubMed

Accurate, selective and sensitive spectrophotometric methods have been developed and validated for simultaneous determination of Cinnarizine and Domperidone, a binary mixture with overlapping spectra, without preliminary separation. These methods include area under the curve (AUC) and dual wavelength spectrophotometry. For the AUC method, the area under curve of mixture solutions in the wavelength ranges 241-258 nm and 280-292 nm were selected for determination of Cinnarizine and Domperidone and by applying Cramer's rule, concentration of each drug was obtained. In dual wavelength method, two wavelengths were selected for each drug in a way so that the difference in absorbance is zero for another drug. Domperidone shows equal absorbance at 240.2 nm and 273.2 nm, where the differences in absorbance were measured for the determination of Cinnarizine. Similarly, differences in absorbance at 230.8 nm and 259.2 nm were measured for determination of Domperidone. The proposed methods were applied for determination of Cinnarizine and Domperidone over the concentration ranges of 2-20 and 2-22 ?g mL(-1), respectively. The suggested methods were validated as per USP guidelines and the results revealed that they are reliable, reproducible and precise for routine use with short analysis time. The results obtained by the proposed methods were statistically compared to the reported method, and there was no significant difference between them regarding both accuracy and precision. PMID:23735208

Abdelrahman, Maha M

2013-09-01

140

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

PubMed

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

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

2014-03-01

141

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

NASA Astrophysics Data System (ADS)

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

Lotfy, Hayam Mahmoud; Abdel-Monem Hagazy, Maha

2012-10-01

142

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

PubMed

Three simple, specific, accurate and precise spectrophotometric methods manipulating ratio spectra are developed for simultaneous determination of omeprazole (OM), tinidazole (TN) and clarithromycin (CL) in tablets. Method A, is an extended ratio subtraction one (EXRSM). Method B is a ratio difference spectrophotometric one (RDSM), while method C is mean centering of ratio spectra (MCR). The calibration curves are linear over the concentration range of 1-20 ?g/mL, 10-60 ?g/mL and 0.25-1.0 mg/mL for OM, TN and CL, respectively. The specificity of the developed methods is investigated by analyzing laboratory prepared mixtures of the three drugs and their combined dosage form. Standard deviation values are less than 1.5 in the assay of raw materials and tablets. The three methods are validated as per ICH guidelines and accuracy, precision, repeatability and robustness are found to be within the acceptable limits. PMID:22683662

Lotfy, Hayam Mahmoud; Abdel-Monem Hagazy, Maha

2012-10-01

143

A novel spectrophotometric method for batch and flow injection determination of sulfite in beverages.  

PubMed

A novel spectrophotometric assay method for batch and flow injection determination of sulfite in beverages is described. The method involves a reaction with diaquacobyrinic acid heptamethyl ester (diaquacobester, DACbs) in acetate buffer of pH 3 to form a highly stable sulfite cobester complex (SO3Cbs). In the absence of sulfite, the reagent displays three absorption maxima at 349, 409 and 525 nm. Addition of sulfite is associated with the development of a new absorption band at 313 nm, an increase in the intensity of the band at 425 nm and a decrease in the absorbance of the bands at 349 and 525 nm. Variations of the absorptions at 313, 349, 425 and 525 nm are linearly proportional to sulfite concentrations over the range of 0.05-25 microg ml(-1)with a detection limit of 0.01-0.2 microg ml(-1). Negligible interferences are caused by most common ions. Validation of the method according to the quality assurance standards shows suitability for quality control assessment of sulfite in complex matrices without prior treatment. The method has the advantages of high selectivity, good sensitivity, fast reaction, high stability of the reagent and reaction product and absorbance measurements at four different wavelengths in the same run. The method is successfully applied to determine the sulfite contents of some beverages. The results compare fairly well with data obtained using the standard method. PMID:17723404

Hassan, Saad S M; Hamza, Mohamed S A; Mohamed, Ayman H K

2006-06-16

144

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

145

A sensitive spectrophotometric method for the determination of desloratadine in tablets.  

PubMed

A simple, rapid, and sensitive visible spectrophotometric method was developed, for the first time, for analysis of desloratadine (DE) in tablets. The method is based on the deep-blue colored TCNQ*- radical anion formed by interaction of the drug (n-donor) with 7,7,8,8-tetracyanoquinodimethane (TCNQ, pi-acceptor) in acetonitrile at ambient temperature. Optimum conditions for the reaction were investigated, absorbances were read at 843 nm, and the linearity range for concentrations of DE was found to be 1.5-13 microg/mL. The reaction product remains stable up to 8 h when kept at room temperature in the dark. The developed method was validated and successfully applied to the determination of DE in tablets. The tablets were also analyzed with a column liquid chromatography method reported in literature. The results from both methods were statistically compared by t- and F-tests. No significant difference was found for the means and standard deviations at 95% confidence level. Accuracy was examined through recovery studies. Being very simple and reliable, the method can be recommended for routine quality control analysis of DE in tablets. PMID:17474507

Ca?lar, Sena; Oztunç, Aysel

2007-01-01

146

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

PubMed

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

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

2004-08-01

147

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

PubMed

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

Moustafa, H; Fayez, Y

2014-12-10

148

Determination of rapid chlorination rate constants by a stopped-flow spectrophotometric competition kinetics method.  

PubMed

Free chlorine is extensively used for water and wastewater disinfection nowadays. However, it still remains a big challenge to determine the rate constants of rapid chlorination reactions although competition kinetics and stopped-flow spectrophotometric (SFS) methods have been employed individually to investigate fast reaction kinetics. In this work, we proposed an SFS competition kinetics method to determine the rapid chlorination rate constants by using a common colorimetric reagent, N,N-diethyl-p-phenylenediamine (DPD), as a reference probe. A kinetic equation was first derived to estimate the reaction rate constant of DPD towards chlorine under a given pH and temperature condition. Then, on that basis, an SFS competition kinetics method was proposed to determine directly the chlorination rate constants of several representative compounds including tetracycline, ammonia, and four ?-amino acids. Although Cl2O is more reactive than HOCl, its contribution to the overall chlorination kinetics of the test compounds could be neglected in this study. Finally, the developed method was validated through comparing the experimentally measured chlorination rate constants of the selected compounds with those obtained or calculated from literature and analyzing with Taft's correlation as well. This study demonstrates that the SFS competition kinetics method can measure the chlorination rate constants of a test compound rapidly and accurately. PMID:24602867

Song, Dean; Liu, Huijuan; Qiang, Zhimin; Qu, Jiuhui

2014-05-15

149

Rapid spectrophotometric method (aqueous and extractive) for the determination of titanium in silicate rocks.  

PubMed

A sensitive and highly selective aqueous as well as extractive spectrophotometric method has been developed for the determination of titanium(IV) using 2,3-dihydroxynaphthalene (H(2)ND) as a chromogenic agent. The reagent (H(2)ND) forms a 1:3 (TiOH(3+):ligand) complex at pH 4-9. The molar absorptivity and Sandell's sensitivity are 3.2 x 10(4) l . mol(-1)mol . cm(-1) and 0.001 microg/cm(2), respectively at lambda(max) 375 nm. The method has been found highly selective for Ti(IV) determination in rock samples. Solvent extraction of Ti(IV) in ethylacetate greatly improves the detection limit of the method. The method has been successfully applied to diverse silicate rock samples and results obtained are favourably comparable with those obtained from the tiron method. The reagent (H(2)ND) used in the present investigation is a much better variant than tiron for titanium(IV) determination in silicate rock samples in terms of sensitivity, selectivity, operational simplicity and economy. PMID:18966077

Tarafder, P K; Durani, S; Saran, R; Ramanaiah, G V

1994-08-01

150

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

151

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

PubMed

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

Gouda, Ayman A; Malah, Zakia Al

2013-03-15

152

Novel Spectrophotometric Method for the Determination of Pindolol in Pharmaceutical Samples  

NASA Astrophysics Data System (ADS)

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

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

2011-10-01

153

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

PubMed

An automated sequential injection (SI) spectrophotometric system has been developed for evaluation of tyramine oxidase (TOD) inhibitory activity. The method is based on the inhibition of TOD that catalyzes the oxidation of tyramine substrate to produce aldehyde and hydrogen peroxide (H2O2). The produced H2O2 reacts with vanillic acid and 4-aminoantipyrine (4-AA) in the presence of peroxidase (POD) to form a quinoneimine dye, the absorbance of which is measured of absorbance at wavelength of 490nm. The decrease of the quinoneimine dye is related to an increase of TOD inhibitory activity. Under the optimum conditions: 1.0mM tyramine, 8UmL(-1) TOD, 1.0mM vanillic acid, 1.0mM 4-AA and delay time of 10s, some flavonoid compounds were examined for the TOD inhibitory activity expressed as IC50 value. It was found that flavonols (quercetin and myricetin) and flavans (epicatechin gallate (ECG) and epigallocatechin (EGC)) showed higher TOD inhibitory activity than flavones and flavanones. The results of IC50 values obtained from the proposed method and a batch-wise method were not significantly different from each other. Moreover, the SI system enabled automation of the analysis, leading to more convenient, more sensitive and faster analysis than the batch-wise method. A precise timing of the system also improves precision and accuracy of the assay, especially when the measurement of absorbance at non-steady state condition is involved. PMID:24720993

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

2014-05-01

154

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

155

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

156

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

PubMed Central

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

2013-01-01

157

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

158

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

NASA Astrophysics Data System (ADS)

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

Chansuvarn, Woravith; Panich, Sirirat; Imyim, Apichat

2013-09-01

159

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

PubMed

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

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

2011-03-01

160

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

161

Spectrophotometric Methods for the Determination of Sitagliptin and Vildagliptin in Bulk and Dosage Forms  

PubMed Central

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

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

2011-01-01

162

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

163

Analysis of residual solvents in ampicillin powder by headspace spectrophotometric method.  

PubMed

In this study a headspace spectrophotometric method is proposed for analysis of dichloromethane and isobutyl methyl keton (IBMK) residues in the ampicillin powder. Ampicillin is dissolved in 1 M NaOH in the vessel of an arsenic analyzer unit of an atomic absorption spectrophotometer. After 3-min stirring, the headspace has flowed by air into the flow-through cell and its absorbance is read at 196 nm, as emitted by a selenium hollow cathode lamp. The absorbance of the headspace is read in two cases (in the presence and absence of MnO4- ion). In the former case, the absorbance is only related to dichloromethane; in the latter, it is related to both solvents. By this method both solvents are determined in the ampicillin samples. The obtained results are compared with gas chromatography (GC) data. These results have good agreement. The proposed method is very rapid, selective and repeatable. Other solvents present, such as isopropyl alcohol, ethylacetate and triethylamine, are not interfering. PMID:11874121

Farajzadeh, Mirali; Mardani, Alireza

2002-02-01

164

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

PubMed

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 affecting the behaviour of the system such as pH, concentration of dPKBH, buffer solution and ethanol, order of addition of the reagents and stability of the complex, were evaluated. The molar absorptivity (epsilon) was 3.92x10(4) L mol(-1) cm(-1), and Beer's law was obeyed up to 3 mg L(-1) of copper. The relative standard deviation was 0.46% (n=11) for a sample containing 1 mg L(-1) Cu(II). The limit of detection was 2.5 micro g L(-1) and was therefore more sensitive than the direct methods reported previously. Finally, the method was successfully validated by analysing several real samples with different matrices, such as tap water, natural water or copper alloys, with an average relative error of 2.46%. PMID:12194048

Pinto, Juan J; Moreno, Carlos; García-Vargas, Manuel

2002-04-01

165

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

PubMed

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

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

2005-01-01

166

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

PubMed

Understanding the role played by chemical additives such as NaCl salt, acid and Cetylpyridinium Chloride (CPC) surfactant on the interaction between dye and polyelectrolyte contributes to optimization of processes using polyelectrolytes in the removal of dye from aqueous solution. Herein we focus in the interaction between Safranin T, a cationic dye, with two anionic polyelectrolytes, poly(ammonium acrylate) and poly(acrylic acid) using spectrophotometric method and conductivity measurement. In aqueous solution, each of anionic polyelectrolytes forms a complex with the dye and induces a metachromasy indicated by the blue shift of the absorbance of the dye. The stoichiometry of complexes evaluated by the molar ratio method are 1:1 for Safranin T poly(ammonium acrylate) and 2:1 in the case of Safranin T poly(acrylic acid). The effect of additives on the stability of complexes has been studied by varying concentrations of the salt and the surfactant and pH of the solution. The thermodynamic parameters of interaction ?G, ?H and ?S at different temperatures were evaluated to determine the stability constant of the complexes. PMID:24830630

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

2014-10-15

167

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

PubMed

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

Chwatko, Grazyna

2013-01-01

168

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

169

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

PubMed

A highly sensitive visible spectrophotometric method has been developed to determine ethamsylate in this paper, which is based on using Cu(II) as spectroscopic probe reagent. The study indicates that in the presence of SCN(-) and KNO(3), Cu(II) is reduced to Cu(I) by ethamsylate at pH 5.0, and the in situ formed Cu(I) reacts with SCN(-) to form into the white emulsion CuSCN that could be stayed upon the surface of water. According to the amount of residual Cu(II), the amount of ethamsylate can be indirectly determined. Under the optimal conditions, Beer's law is applicable in the range of 0.2-9.0 microg/mL (7.60x10(-7)-3.42x10(-5)mol/L) for aqueous standard solution of ethamsylate with linear correlation coefficient of 0.9998. The detection limit and relative standard deviation are 0.12 microg/mL and 1.5%, respectively. And the molar absorption coefficient of the indirect determination of ethamsylate is 1.0x10(5)L/mol cm. The method is successfully applied to determine ethamsylate in pharmaceutical preparations and biological samples. PMID:20060358

Zhang, Meiyun; Zhang, Yan; Li, Quanmin

2010-03-01

170

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

NASA Astrophysics Data System (ADS)

A highly sensitive visible spectrophotometric method has been developed to determine ethamsylate in this paper, which is based on using Cu(II) as spectroscopic probe reagent. The study indicates that in the presence of SCN - and KNO 3, Cu(II) is reduced to Cu(I) by ethamsylate at pH 5.0, and the in situ formed Cu(I) reacts with SCN - to form into the white emulsion CuSCN that could be stayed upon the surface of water. According to the amount of residual Cu(II), the amount of ethamsylate can be indirectly determined. Under the optimal conditions, Beer's law is applicable in the range of 0.2-9.0 ?g/mL (7.60 × 10 -7-3.42 × 10 -5 mol/L) for aqueous standard solution of ethamsylate with linear correlation coefficient of 0.9998. The detection limit and relative standard deviation are 0.12 ?g/mL and 1.5%, respectively. And the molar absorption coefficient of the indirect determination of ethamsylate is 1.0 × 10 5 L/mol cm. The method is successfully applied to determine ethamsylate in pharmaceutical preparations and biological samples.

Zhang, Meiyun; Zhang, Yan; Li, Quanmin

2010-03-01

171

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

172

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

PubMed

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

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

2007-01-01

173

Studies on Tinospora cordifolia monosugars and correlation analysis of uronic acids by spectrophotometric methods and GLC.  

PubMed

Cold water-soluble (CWSP) and hot water soluble polysaccharides (HWSP) from Tinospora cordifolia stems were isolated and purified in 2.99% and 1.99% yield respectively. Complete hydrolysis followed by paper chromatography and GLC analysis indicated the presence of L-rhamnose, L-arabinose, D-xylose, D-mannose, D-galactose and D-glucose in molar ratio of 0.857, 1.106, 0.727, 0.526, 0.708 and 95.763 in CWSP and 0.697, 0.777, 2.048, 0.777, 0.292 and 95.408 in HWSP. The uronic acid content in the polysaccharide has been studied extensively using assorted approaches. It was quantitatively estimated by GLC analysis and spectrophotometric methods using carbazole, m-hydroxydiphenyl and 3,5-dimethylphenol as colorimetric reagents. GLC analyses indicated galacturonic acid content of 3.06% and 5.16% in CWSP and HWSP respectively. Estimation of uronic acid using 3,5-dimethylphenol corroborated the above analysis. The study resulted in composition of constituent monosugars of CWSP and HWSP and co-relation analysis of uronic acid content, leading to an unambiguous structural analysis. PMID:24274509

Kumar, Vineet; Nagar, Shipra

2014-01-01

174

Linear optical methods for temporal characterization of femtosecond UV pulses  

NASA Astrophysics Data System (ADS)

The realization of a first-order interferometric autocorrelator in a nearly collinear geometry is reported as an alternative method to measure the minimum pulse duration of femtosecond deep-UV laser pulses. The Fourier limited duration of 257-nm femtosecond pulses is measured with high accuracy, and compared to what obtained by spectrally measuring the bandwidth of the pulses. The agreement between the two methods is excellent, thus indicating the interferometric autocorrelator as a useful tool to extract the chirp of femtosecond UV pulses when used together with a second-order autocorrelator to measure the actual pulse duration.

Valadan, Mohammadhassan; D'Ambrosio, Davide; Gesuele, Felice; Velotta, Raffaele; Altucci, Carlo

2014-05-01

175

Chromium speciation in environmental samples using a solid phase spectrophotometric method.  

PubMed

A solid phase extraction technique is proposed for preconcentration and speciation of chromium in natural waters using spectrophotometric analysis. The procedure is based on sorption of chromium(III) as 4-(2-benzothiazolylazo)2,2'-biphenyldiol complex on dextran-type anion-exchange gel (Sephadex DEAE A-25). After reduction of Cr(VI) by 0.5 ml of 96% concentrated H(2)SO(4) and ethanol, the system was applied to the total chromium. The concentration of Cr(VI) was calculated as the difference between the total Cr and the Cr(III) content. The influences of some analytical parameters such as: pH of the aqueous solution, amounts of 4-(2-benzothiazolylazo)2,2'-biphenyldiol (BTABD), and sample volumes were investigated. The absorbance of the gel, at 628 and 750 nm, packed in a 1.0 mm cell, is measured directly. The molar absorptivities were found to be 2.11×10(7) and 3.90×10(7) L mol(-1)cm(-1) for 500 and 1000 ml, respectively. Calibration is linear over the range 0.05-1.45 ?g L(-1) with RSD of <1.85% (n=8.0). Using 35 mg exchanger, the detection and quantification limits were 13 and 44 ng L(-1) for 500 ml sample, whereas for 1000 ml sample were 8.0 and 27 ng L(-1), respectively. Increasing the sample volume can enhance the sensitivity. No considerable interferences have been observed from other investigated anions and cations on the chromium speciation. The proposed method was applied to the speciation of chromium in natural waters and total chromium preconcentration in microwave digested tobacco, coffee, tea, and soil samples. The results were simultaneously compared with those obtained using an ET AAS method, whereby the validity of the method has been tested. PMID:22766579

Amin, Alaa S; Kassem, Mohammed A

2012-10-01

176

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

NASA Astrophysics Data System (ADS)

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

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

177

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

PubMed

A selective and simple kinetic spectrophotometric has been developed, for the first time, for the determination of gatifloxacin (GAT) in its dosage forms. The method was based on the formation of a colored N-vinyl chlorobenzoquinone derivative of GAT by its reaction with 2,3,5,6-tetrachloro-1,4-benzoquinone in presence of acetaldehyde. The formation of the colored product was monitored spectrophotometrically by measuring the absorbances at 655 nm. The factors affecting the reaction were studied and optimized. The stoichiometry of the reaction was determined, and the reaction pathway was postulated. Under the optimized conditions, the initial rate and fixed time (at 5 min) methods were utilized for constructing the calibration graphs. The graphs were linear in the concentration ranges of 2-100 and 10-140 microg ml(-1) with limits of detection of 0.84 and 3.5 microg ml(-1) for the initial rate and fixed time methods, respectively. The analytical performance of both methods was fully validated, and the results were satisfactory. The proposed methods were successfully applied to the determination of GAT in its commercial dosage forms. The label claim percentages were 99.7-100.5 and 98.2-99.5% for the initial rate and fixed time methods, respectively. Statistical comparison of the results with those of the reference method showed excellent agreement and proved that there was no significant difference in the accuracy and precision between the reference and the proposed methods. The proposed methods are superior to all the previously reported spectrophotometric methods in terms of the procedure simplicity and assay selectivity. PMID:19939728

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

2010-01-01

178

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

PubMed Central

Methods for the detection and estimation of diphosgene and triphosgene are described. These compounds are widely used phosgene precursors which produce an intensely colored purple pentamethine oxonol dye when reacted with 1,3-dimethylbarbituric acid (DBA) and pyridine (or a pyridine derivative). Two quantitative methods are described, based on either UV absorbance or fluorescence of the oxonol dye. Detection limits are ~ 4 µmol/L by UV and <0.4 µmol/L by fluorescence. The third method is a test strip for the simple and rapid detection and semi-quantitative estimation of diphosgene and triphosgene, using a filter paper embedded with dimethylbarbituric acid and poly(4-vinylpyridine). Addition of a test solution to the paper causes a color change from white to light blue at low concentrations and to pink at higher concentrations of triphosgene. The test strip is useful for quick on-site detection of triphosgene and diphosgene in reaction mixtures. The test strip is easy to perform and provides clear signal readouts indicative of the presence of phosgene precursors. The utility of this method was demonstrated by the qualitative determination of residual triphosgene during the production of poly(Bisphenol A carbonate).

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

2009-01-01

179

A new spectrophotometric method for the determination of dithianon in commercial formulations and its residues in foodstuffs.  

PubMed

A new, simple, and rapid spectrophotometric method for the microdetermination of dithianon, on the basis of its reaction with a dithiocarbamate, is described. The red color, which develops instantaneously when mixing the fungicide with the reagent in acetonitrile, is stable for at least 1 h and is measured at 520 nm. Beer's law is applicable up to 12 micrograms/mL dithianon concentration. The method has been successfully adapted to the analysis of the fungicide in commercial formulations and its residues on grains and apple (fruit and leaves). A photometric titration method for formulation analysis of the fungicide has also been developed. PMID:10589480

Verma, B C; Thakur, H K; Singh, J; Sharma, D K

1999-01-01

180

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

NASA Astrophysics Data System (ADS)

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

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

2007-11-01

181

A selective spectrophotometric method for determination of quercetin in the presence of other flavonoids.  

PubMed

A simple, rapid and highly selective method for determination of quercetin in the presence of other flavonoids was developed. The method is based on the oxidation reaction of quercetin in neutral aqueous solution with N-bromosuccinimide (NBS) in the presence of phenol to give a violet chromogen measurable at 510 nm. Beer's law was valid within a concentration range of 2.5-30 mug/ml with a good correlation coefficient (r = 0.9990). All variables were studied to optimize the reaction conditions. The method is highly selective for quercetin. Other investigated flavonoids do not interfere. Mixtures of flavonoids were also analysed through native UV measurements of absorbance readings at 370 nm and then at 510 mn after adopting the proposed procedure. The method could also be utilized for the quantitative determination of quercetin in some plant extracts. Moreover, the proposed procedure could be considered as a good tool to follow the hydrolysis of quercetin glycosides. PMID:18965372

Askal, H F; Saleh, G A; Backheet, E Y

1992-03-01

182

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

PubMed

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

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

2012-01-01

183

Comparison of methods of enumerating coliforms after UV disinfection.  

PubMed Central

In view of the differences that have been found between the most-probable-number and membrane filtration methods for the recovery of coliforms from chlorinated samples, the survival of total and fecal coliforms in UV-irradiated effluent samples, as tested by the most-probable-number and standard single-step membrane filtration methods, was compared. There were no significant differences in the survival of total and fecal coliforms, as tested by the two methods. In a separate set of experiments comparing total and fecal coliform survival, as tested by the most-probable-number method, only a very small but statistically significant difference of 0.1 log survival units was found. For UV-disinfected wastewater effluents, standard one-step membrane filtration procedures are comparable to standard most-probable-number procedures.

Qualls, R G; Chang, J C; Ossoff, S F; Johnson, J D

1984-01-01

184

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

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

185

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

PubMed Central

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

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

2011-01-01

186

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 1–10 ?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 0.3–8 ?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.

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

2010-01-01

187

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

PubMed

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

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

2013-12-15

188

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

PubMed

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

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

2011-01-01

189

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

PubMed

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

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

2011-03-15

190

Nucleic Acid (DNA, RNA) Quantification and RNA/DNA Ratio Determination in Marine Sediments: Comparison of Spectrophotometric, Fluorometric, and HighPerformance Liquid Chromatography Methods and Estimation of Detrital DNA  

PubMed Central

In this study, we compared three methods for extraction and quantification of RNA and DNA from marine sediments: (i) a spectrophotometric method using the diphenylamine assay; (ii) a fluorometric method utilizing selective fluorochromes (thiazole orange for total nucleic acids and Hoechst 33258 for DNA); and (iii) a high-pressure liquid chromatography (HPLC) method which uses a specific column to separate RNA and DNA and UV absorption of the nucleic acids for quantification. Sediment samples were collected in the oligotrophic Cretan Sea (eastern Mediterranean, from 40 to 1,540 m in depth) and compared to the distribution and composition of the benthic microbial assemblages (i.e., bacteria and microprotozoa). DNA concentrations measured spectrophotometrically and by HPLC were not significantly different, while fluorometric yields were significantly lower. Such differences appear mainly due to fact that the stain-DNA complex is strongly dependent on the DNA composition and structure. RNA concentrations determined by the three methods displayed some differences; fluorometric and spectrophotometric methods obtain RNA concentration by difference and therefore may be biased by DNA estimates. By contrast, the HPLC method provides independent assessments of RNA and DNA concentrations. We tentatively estimated the contribution of the detrital DNA to the total DNA pools in two ways. The two calculations provided quite similar results indicating that the majority of the DNA pool in the deep-sea sediments was detrital. Microbial RNA generally accounted for almost the entire sedimentary RNA pools below 100-m depth. RNA concentrations were found to decrease along the Cretan shelf and slope. The RNA/DNA ratio calculated by using fluorometric DNA concentrations was significantly correlated with values of sediment community oxygen consumption only below 100-m depth (dominated by the microbial biomass). These data suggest that the RNA/DNA ratio, based on fluorometric estimates of DNA, can be used as an indicator of benthic metabolic activity, but only when metazoan contribution to the microbial DNA is negligible.

Dell'Anno, A.; Fabiano, M.; Duineveld, G. C. A.; Kok, A.; Danovaro, R.

1998-01-01

191

Generalized net analyte signal standard addition as a novel method for simultaneous determination: application in spectrophotometric determination of some pesticides.  

PubMed

Simultaneous spectrophotometric determination of three neonicotinoid insecticides (acetamiprid, imidacloprid, and thiamethoxam) by a novel method named generalized net analyte signal standard addition method (GNASSAM) in some binary and ternary synthetic mixtures was investigated. For this purpose, standard addition was performed using a single standard solution consisting of a mixture of standards of all analytes. Savings in time and amount of used materials are some of the advantages of this method. All determinations showed appropriate applicability of this method with less than 5% error. This method may be applied for linearly dependent data in the presence of known interferents. The GNASSAM combines the advantages of both the generalized standard addition method and net analyte signal; therefore, it may be a proper alternative for some other multivariate methods. PMID:24672886

Asadpour-Zeynali, Karim; Saeb, Elhameh; Vallipour, Javad; Bamorowat, Mehdi

2014-01-01

192

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

193

Validation of a modified spectrophotometric method for the determination of nitrate in dry milk using 2-sec-butylphenol.  

PubMed

A rapid, simple and direct visible spectrophotometric method, based on the quantitative nitration of 2-sec-butylphenol in concentrated sulfuric acid, is described for the determination of nitrate in milk. The nitration product was extracted into toluene and the yellow nitrophenoxide compound formed in alkaline aqueous solution was determined at 418 nm. Carrez reagents were used for protein precipitation. Interference from lactose, chloride and nitrite ions and the effect of reagent concentration was controlled. The calibration graph was linear over the range 0.5-5 micrograms ml-1 NO3-; y = -0.0019 + 0.0681 x; r = 0.9997. The limits of detection and quantification were found to be 0.18 and 0.5 microgram ml-1 NO3-, respectively. The accuracy of the method did not depend on nitrate content in spiked milk. The mean recovery of the spiked milk was found to be 99.81% with the confidence limits of 0.67%, a relative standard deviation (RSDr) of 1.79% for repeatability and an RSDR value of 1.90% for reproducibility. Adequate agreement was found between results obtained by the nitration method and those of the French official reduction spectrophotometric reference method (AFNor). For the Indonesian dry (powdered) milk sample studied the nitrate levels were in the range 10.7-29.5 mg kg-1 NO3-. PMID:7492033

Bintoro, V P; Cantin-Esnault, D; Alary, J

1995-11-01

194

Spectrophotometric information from the DIVA satellite  

NASA Astrophysics Data System (ADS)

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

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

2003-01-01

195

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

196

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

PubMed

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

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

2005-01-01

197

Speciation and analysis of arsenic(III) and arsenic(V) by electrochemical hydride generation spectrophotometric method.  

PubMed

A simple method was developed for speciation and spectrophotometric determination of inorganic As(III) and As(V) using an electrochemical hydride generation technique. For speciation of As(III) and As(V), a graphite rod was used as cathode to reduce As(III) to AsH(3), the rod was then replaced with a tin-lead alloy wire for reducing As(V) to AsH(3). The spectrophotometric determination was based on the reaction of AsH(3) with silver diethyldithiocarbamate to give an absorbing complex at 510 nm. Under the optimized conditions, the calibration curves were linear over the ranges of 0.1-5 microg ml(-1) for As(III) and 0.5-4.0 microg ml(-1) for As(V). The concentration detection limits of 0.02 and 0.06 microg ml(-1) were achieved for As(III) and As(V), respectively. The relative standard deviations for five replicate speciation and determination of 3.0 microg ml(-1) As(III) and As(V) were 0.8 and 7.2%, respectively. The accuracy and recovery of the method were evaluated by analyzing tap water spiked with As(III) and As(V). PMID:20065596

Arbab-Zavar, Mohammad Hossein; Chamsaz, Mahmoud; Heidari, Tahereh

2010-01-01

198

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

199

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

200

Development and Validation of a Stability-indicating UV Spectroscopic Method for Candesartan in Bulk and Formulations.  

PubMed

A simple, specific, accurate and stability-indicating UV- Spectrophotometric method was developed for the estimation of candesartan cilexitil, using a Shimadzu, model 1700 spectrophotometer and a mobile phase composed of methanol: water in the ratio of 9:1 at wave length (?(max)) 254 nm. Linearity was established for candesartan in the range of 10-90 ?g/ml. The percentage recovery of was found to be in the range of 99.76-100.79%. The drug was subjected to acid, alkali and neutral hydrolysis, oxidation, dry heat, UV light and photolytic degradation. Validation experiments performed to demonstrate system suitability, specificity, precision, linearity, accuracy, interday assay, intraday assay, robustness, ruggedness, LOD, and LOQ. While estimating the commercial formulation there was no interference of excipients and other additives. Hence this method can be used for routine determination of candesartan cilexetil in bulk and their pharmaceutical dosage forms. The proposed method for stability study shows that there was appreciable degradation found in stress condition of candesartan. PMID:23112408

Pradhan, K K; Mishra, U S; Pattnaik, S; Panda, C K; Sahu, K C

2011-11-01

201

Development and Validation of a Stability-indicating UV Spectroscopic Method for Candesartan in Bulk and Formulations  

PubMed Central

A simple, specific, accurate and stability-indicating UV- Spectrophotometric method was developed for the estimation of candesartan cilexitil, using a Shimadzu, model 1700 spectrophotometer and a mobile phase composed of methanol: water in the ratio of 9:1 at wave length (?max) 254 nm. Linearity was established for candesartan in the range of 10-90 ?g/ml. The percentage recovery of was found to be in the range of 99.76-100.79%. The drug was subjected to acid, alkali and neutral hydrolysis, oxidation, dry heat, UV light and photolytic degradation. Validation experiments performed to demonstrate system suitability, specificity, precision, linearity, accuracy, interday assay, intraday assay, robustness, ruggedness, LOD, and LOQ. While estimating the commercial formulation there was no interference of excipients and other additives. Hence this method can be used for routine determination of candesartan cilexetil in bulk and their pharmaceutical dosage forms. The proposed method for stability study shows that there was appreciable degradation found in stress condition of candesartan.

Pradhan, K. K.; Mishra, U. S.; Pattnaik, S.; Panda, C. K.; Sahu, K. C.

2011-01-01

202

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

PubMed

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

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

2012-09-01

203

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

204

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

PubMed

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

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

2012-01-01

205

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

PubMed Central

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

2012-01-01

206

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

NASA Technical Reports Server (NTRS)

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

Dupraw, W. A.

1972-01-01

207

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

208

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

209

Validated spectrophotometric quantification of aripiprazole in pharmaceutical formulations by using multivariate technique.  

PubMed

Purpose: An accurate and precise UV spectrophotometric method with multivariate calibration technique for the determination of aripiprazole in pharmaceutical formulations has been described. Methods: This technique is based on the use of the linear regression equations by using the relationship between concentration and absorbance at five different wavelengths. The aripiprazole shows absorption maxima at 255 nm and obeyed Beer's law in the range of 5-30 µg/mL. Results: The results were treated statistically and were found highly accurate, precise and reproducible. This statistical approach gives optimum results for the eliminating fluctuations coming from instrumental or experimental conditions. Conclusion: It was concluded that the proposed method is simple, easy to apply, economical and could be used as an alternative to the existing spectrophotometric and non-spectrophotometric methods for the routine analysis of aripiprazole in pharmaceutical formulations. PMID:24312881

Sandeep, Kandikonda; Induri, Madhusudhanareddy; Sudhakar, Muvvala

2013-01-01

210

Validated Spectrophotometric Quantification of Aripiprazole in Pharmaceutical Formulations by Using Multivariate Technique  

PubMed Central

Purpose: An accurate and precise UV spectrophotometric method with multivariate calibration technique for the determination of aripiprazole in pharmaceutical formulations has been described. Methods: This technique is based on the use of the linear regression equations by using the relationship between concentration and absorbance at five different wavelengths. The aripiprazole shows absorption maxima at 255 nm and obeyed Beer’s law in the range of 5-30 µg/mL. Results: The results were treated statistically and were found highly accurate, precise and reproducible. This statistical approach gives optimum results for the eliminating fluctuations coming from instrumental or experimental conditions. Conclusion: It was concluded that the proposed method is simple, easy to apply, economical and could be used as an alternative to the existing spectrophotometric and non-spectrophotometric methods for the routine analysis of aripiprazole in pharmaceutical formulations.

Sandeep, Kandikonda; Induri, Madhusudhanareddy; Sudhakar, Muvvala

2013-01-01

211

UV treatment of fishmeal: a method to remove dioxins?  

PubMed

This study evaluates the use of UV on contaminated fishmeal and photodegradation of dioxins. Fishmeal samples were placed under UVA or UVB light for 2, 5, and 10 days. Subsequently, analysis of amino acid content, lipid oxidation marker, ethoxyquin content, dioxin, and polychlorinated biphenyl (PCB) profiling was carried out. Exposure of fishmeal for 5 days to UVB light resulted in the degradation of approximately 70% of the dioxin content, while UVA had little effect, only resulting in the degradation of 10% of the dioxin content. UVB did not affect the protein and amino acid content of fishmeal; however, lipid oxidation was triggered. Addition of ethoxyquin prevented oxidation but simultaneously slowed dioxin breakdown. Increasing UVB intensity resulted in a more efficient dioxin degradation of 90%. Exposure of fishmeal to UVB also resulted in an increase in PCBs. UVB light is shown to photodegrade dioxin in fishmeal, indicating the needs to further investigation of methods for application at industrial scale. PMID:16131115

Baron, Caroline P; Břrresen, Torger; Jacobsen, Charlotte

2005-09-01

212

Selective Spectrophotometric and Spectrofluorometric Methods for the Determination of Amantadine Hydrochloride in Capsules and Plasma via Derivatization with 1,2-Naphthoquinone-4-sulphonate  

PubMed Central

New selective and sensitive spectrophotometric and spectrofluorometric methods have been developed and validated for the determination of amantadine hydrochloride (AMD) in capsules and plasma. The methods were based on the condensation of AMD with 1,2-naphthoquinone-4-sulphonate (NQS) in an alkaline medium to form an orange-colored product. The spectrophotometric method involved the measurement of the colored product at 460 ?nm. The spectrofluorometric method involved the reduction of the product with potassium borohydride, and the subsequent measurement of the formed fluorescent reduced AMD-NQS product at 382 ?nm after excitation at 293 ?nm. The variables that affected the reaction were carefully studied and optimized. Under the optimum conditions, linear relationships with good correlation coefficients (0.9972–0.9974) and low LOD (1.39 and 0.013??g?mL?1) were obtained in the ranges of 5–80 and 0.05–10? ?g?mL?1 for the spectrophotometric and spectrofluorometric methods, respectively. The precisions of the methods were satisfactory; RSD ?2.04%. Both methods were successfully applied to the determination of AMD in capsules. As its higher sensitivity, the spectrofluorometric method was applied to the determination of AMD in plasma; the recovery was 96.3–101.2 ± 0.57–4.2%. The results obtained by the proposed methods were comparable with those obtained by the official method

Mahmoud, Ashraf M.; Khalil, Nasr Y.; Darwish, Ibrahim A.; Aboul-Fadl, Tarek

2009-01-01

213

Development and validation of a spectrophotometric method for the determination of macrolide antibiotics by using 2,4-dinitrophenylhydrazine.  

PubMed

A simple, novel, sensitive, and specific spectrophotometric method was developed and validated for the determination of azithromycin (AZ), clarithromycin (CLA), and roxithromycin (ROX) in bulk powders and their dosage forms. The proposed method was based on the interaction of any of the cited drugs with 2,4-dinitrophenylhydrazine in the presence of an acid catalyst, followed by treatment with a methanolic solution of potassium hydroxide; an intensely colored chromogen was formed that was measured in dimethylformamide, as the diluting solvent, at 542-545, 523-526, and 539-542 nm for AZ, CLA, and ROX, respectively. All variables affecting the development of the measured chromogens were studied and optimized. Beer's law was obeyed in the concentration ranges of 5-40, 5-35, and 5-35 microg/mL for AZ, CLA, and ROX, respectively, with good correlation coefficients (0.9991-0.9999). The limits of detection for this method ranged from 0.77 to 1.47 microg/mL, and the relative standard deviations were 1.24-1.8%. The proposed method was applied successfully to the determination of the 3 drugs in pure bulk form, tablets, and suspensions without interference from commonly encountered additives. The results compared favorably with those of a previously reported method. The mechanism of the reaction was also studied. PMID:17474506

Abdelmageed, Osama H

2007-01-01

214

[Quantitation of UV-absorbing admixtures in preparations of D-nucleosides, nucleoside-5'-mono and triphosphates].  

PubMed

The paper describes a method for measuring UV-absorbing admixtures in preparations of D-nucleosides, nucleoside-5'-mono- and triphosphates by chromatographic separation on Silufol UV-254 plates and elution of the separated compounds by means of a modified descending chromatography followed by spectrophotometric measurement of optic density. PMID:7335625

Gorokhov, A F; Pupkova, V I

1981-01-01

215

Photolytic decolorization of Rose Bengal by UV\\/H 2O 2 and data optimization using response surface method  

Microsoft Academic Search

Rose Bengal (C.I. name is Acid Red 94) was irradiated with UV light in the presence of hydrogen peroxide. The photoinduced decolorization of the dye was monitored spectrophotometrically. The apparent rate of decolorization was calculated from the observed absorption data and was found to be pseudo first order. A systematic study of the effect of dye concentration and H2O2 concentration

M. A. Rauf; N. Marzouki; Bahadir K. Körbahti

2008-01-01

216

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

PubMed Central

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

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

2010-01-01

217

Spectrophotometric method for the determination of verapamil hydrochloride in pharmaceutical formulations using N-bromosuccinimide as oxidant.  

PubMed

A rapid, simple and sensitive validated visible spectrophotometric method has been described for the assay of verapamil hydrochloride either in pure form or in pharmaceutical formulations. The method involves the oxidation of the verapamil hydrochloride with N-bromosuccinimide in perchloric acid medium at room temperature, leading to the formation of a yellow colored product, which absorbs maximally at 415 nm. Under the optimized experimental conditions, the color is stable up to 45 min and Beer's law is obeyed in the concentration range of 10.0-200.0 microg ml(-1) with molar absorptivity and Sandell's sensitivity of 2.55 x 10(3) l mol(-1) cm(-1) and 0.192 microg cm(-2) per 0.001 absorbance unit, respectively. The method has been successfully applied to the determination of the drug in commercial dosage forms. Statistical comparison of the results with those of a reference method by means of point and interval hypothesis shows excellent agreement and indicates no significant difference in accuracy and precision. Results of analyses were optimized and validated statistically and through recovery studies. The experimental true bias of all samples is smaller than +/-2%. PMID:15231428

Rahman, Nafisur; Hejaz Azmi, Syed Najmul

2004-07-01

218

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

PubMed

New, simple and rapid spectrophotometric method has been developed and validated for the assay of two macrolide drugs, azithromycin (AZT) and erythromycin (ERY) in pure and pharmaceutical formulations. The proposed method was based on the reaction of AZT and ERY with sodium 1,2-naphthoquinone-4-sulphonate (NQS) in alkaline medium at 25 °C to form an orange-colored product of maximum absorption peak at 452 nm. All variables were studied to optimize the reaction conditions and the reaction mechanism was postulated. Beer's law was obeyed in the concentration range 1.5-33.0 and 0.92-8.0 ?g mL(-1) with limit of detection values of 0.026 and 0.063 ?g mL(-1) for AZT and ERY, respectively. The calculated molar absorptivity values are 4.3 × 10(4) and 12.3 × 10(4) L mol(-1) cm(-1) for AZT and ERY, respectively. The proposed methods were successfully applied to the determination of AZT and ERY in formulations and the results tallied well with the label claim. The results were statistically compared with those of an official method by applying the Student's t-test and F-test. No interference was observed from the concomitant substances normally added to preparations. PMID:23041925

Ashour, Safwan; Bayram, Roula

2012-12-01

219

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

NASA Astrophysics Data System (ADS)

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

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

2011-10-01

220

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

PubMed

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

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

2013-05-01

221

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

PubMed Central

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

2013-01-01

222

A simple and high sensitive spectrophotometric method for ultra trace determination of ruthenium with its catalytic effect on the oxidation of pyronin B by periodate  

Microsoft Academic Search

A new simple, selective, high sensitive and rapid method has been developed for spectrophotometric determination of ultra trace amounts of ruthenium based on its catalytic effect on the oxidation of pyronin B by periodate at ?max=555nm. The described method is able to quantitize ruthenium in the range of 0.1–100ngml?1 (r=0.9973), with a detection limit (S\\/N=3) of 0.036ngml?1. Under optimum conditions,

Behzad Rezaei; Najmeh Majidi

2007-01-01

223

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

224

Simultaneous spectrophotometric determination of Hg2+, Pb2+, and Cu2+ by Zn(dmit) using the multivariate calibration method.  

PubMed

This work investigates the applicability of the anionic complex [NBu4]2[Zn(1,3-dithiol-2-tione-4,5-dithiolate)2] on the simultaneous spectrophotometric determination of transition metals. Principal Component Regression was used in the data analysis. This method was used to determine Hg2+, Cu2+ and Pb2+ in water solution, at t = 0, 20 and 60 min of reaction. The root mean square errors (rms) for Hg2+, Cu2+, Pb2+ were 1.92 x 10(-7), 1.89 x 10(-7) and 9.35 x 10(-8) for t = 0 min, 1.79 x 10(-7), 2.1 x 10(-7) and 2.22 x 10(-7) for t = 20 min and 1.22 x 10(-7), 1.31 x 10(-7) and 1.10 x 10(-7) for t = 60 min, respectively. Results showed the viability of the method in determining concentrations of metallic ions in aqueous medium with high spectral overlap. It is an efficient alternative method for exploring the kinetic behavior of multicomponents systems of interest in physicochemical research. PMID:15913146

Barreto, Wagner J; Barreto, Sônia R G; Ruiz, Leila D; Ishikawa, Dilson N; Scarmínio, Ieda S

2005-05-01

225

Use of lignin extracted from different plant sources as standards in the spectrophotometric acetyl bromide lignin method.  

PubMed

A nongravimetric acetyl bromide lignin (ABL) method was evaluated to quantify lignin concentration in a variety of plant materials. The traditional approach to lignin quantification required extraction of lignin with acidic dioxane and its isolation from each plant sample to construct a standard curve via spectrophotometric analysis. Lignin concentration was then measured in pre-extracted plant cell walls. However, this presented a methodological complexity because extraction and isolation procedures are lengthy and tedious, particularly if there are many samples involved. This work was targeted to simplify lignin quantification. Our hypothesis was that any lignin, regardless of its botanical origin, could be used to construct a standard curve for the purpose of determining lignin concentration in a variety of plants. To test our hypothesis, lignins were isolated from a range of diverse plants and, along with three commercial lignins, standard curves were built and compared among them. Slopes and intercepts derived from these standard curves were close enough to allow utilization of a mean extinction coefficient in the regression equation to estimate lignin concentration in any plant, independent of its botanical origin. Lignin quantification by use of a common regression equation obviates the steps of lignin extraction, isolation, and standard curve construction, which substantially expedites the ABL method. Acetyl bromide lignin method is a fast, convenient analytical procedure that may routinely be used to quantify lignin. PMID:21375240

Fukushima, Romualdo S; Kerley, Monty S

2011-04-27

226

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

PubMed

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?gmL(-1) aspirin, 0.8-30?gmL(-1) atorvastatin and 0.5-30?gmL(-1) clopedogrel. In the quotient method, 0.8-40?gmL(-1) aspirin, 0.8-30?gmL(-1) atorvastatin and 1.0-30?gmL(-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?gmL(-1) aspirin, 0.8-30?gmL(-1) atorvastatin and 2.0-30?gmL(-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. PMID:24691365

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

2014-07-15

227

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

228

Accelerated UV Test Methods for Encapsulants of Photovoltaic Modules: Preprint  

SciTech Connect

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

Kempe, M. D.

2008-05-01

229

UV-C radiation based methods for aqueous metoprolol elimination.  

PubMed

The endocrine disruptor metoprolol has been oxidised in aqueous solution by means of the systems UV-C, UV-C/H(2)O(2), UV-C/percarbonate, UV-C/monopersulfate, UV-C/TiO(2), UV-C/H(2)O(2)/TiO(2) and photo-Fenton. From simple photolysis experiments the quantum yield of metoprolol has been calculated (roughly 5x10(-3) mol Einstein(-1) at circumneutral pH). Addition of free radicals promoters significantly enhanced the metoprolol depletion rate. Mineralization degree was negligible when no promoter was added, while low values were achieved in the presence of either inorganic peroxides or titanium dioxide. The combination of radiation, hydrogen peroxide and TiO(2) increased the mineralization level up to values in the proximity of 45-50% under the best conditions investigated. The photo-Fenton process was the best system in terms of total oxidation (mineralization degree 70%) when optimum conditions were applied. PMID:20347220

Rivas, F J; Gimeno, O; Borralho, T; Carbajo, M

2010-07-15

230

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

PubMed

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

Pohanka, Miroslav; Drtinova, Lucie

2013-03-15

231

Spectrophotometric enzymatic cycling method using l-glutamate dehydrogenase and d-phenylglycine aminotransferase for determination of l-glutamate in foods  

Microsoft Academic Search

This report describes a new spectrophotometric method capable of determining low levels of l-glutamate. The assay is based on substrate cycling between l-glutamate dehydrogenase (GlDH) and the novel enzyme d-phenylglycine aminotransferase (d-PhgAT). In this system, GlDH converts l-glutamate to 2-oxoglutarate with concomitant reduction of NAD+ to NADH. The 2-oxoglutarate is recycled to l-glutamate in a transamination reaction catalyzed by d-PhgAT

Wanida Khampha; Vithaya Meevootisom; Suthep Wiyakrutta

2004-01-01

232

pH and buffering capacity problems involved in the determination of ammonia in saline water using the indophenol blue spectrophotometric method  

Microsoft Academic Search

Magnesium ions in brackish water or sea water complex with the citrate reagent (CIT) and thus interfere with the indophenol blue spectrophotometric method for ammonia measurement by altering the final pH of the color solution. The complex system, possibly Mg(CIT)?+OH??Mg(OH)(CIT)2?, shows buffer characteristics and can be identified by acid–base titration. A maximum capacity of ca. 40?eqpH?1ml?1 was found at pH

Su-Cheng Pai; Yung-Jin Tsau; Tai-I Yang

2001-01-01

233

A kinetic spectrophotometric method for the determination of ternary mixtures of reducing sugars with the aid of artificial neural networks and multivariate calibration  

Microsoft Academic Search

A differential spectrophotometric method has been developed for the simultaneous quantitative determination of glucose (GLU), fructose (FRU) and lactose (LAC) in food samples. It relies on the different kinetic rates of the analytes in their oxidative reaction with potassium ferricyanide (K3Fe(CN)6) as the oxidant. The reaction data were recorded at the analytical wavelength (420nm) of the K3Fe(CN)6 spectrum. Since the

Yongnian Ni; Chunfang Huang; Serge Kokot

2003-01-01

234

Spectrophotometric FIA methods for determination of hydrogen peroxide: application to evaluation of scavenging capacity.  

PubMed

The determination of hydrogen peroxide (H(2)O(2)) and the evaluation of scavenging capacity against this species were performed using five colorimetric reactions, which were adapted to flow injection analysis. The reactions chosen were based on the oxidation of iodide (I(-) method), on the formation of titanium-peroxide complex (TiP method), on the formation of titanium-xylenol orange-peroxide complex (TiXoP method), on the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB method) and on the co-oxidation of phenol-4-sulfonic acid and 4-aminoantipyrine (PSA/4-AAP method). The operational conditions were studied in order to improve the sensitivity of each method. Concerning to the method sensitivity, the ranking order was TMB method>I(-) method>TiXoP method approximately PSA/4-AAP method>TiP method. All methods showed an excellent repeatability (RSD<2%) and, except for I(-) method, relative deviations from the reference method were <1.9%. The FIA manifolds were adapted to perform the determination of scavenging capacity against H(2)O(2) and glutathione (GSH) was applied as model compound. TiP and TiXoP methods were not suitable as no inhibition or an increase of analytical signal was attained. PSA/4-AAP method was chosen for further application to dietary phenolics and pharmaceutical compounds, providing IC(50) values for those compounds that are fast reacting antioxidants. PMID:19615527

Ribeiro, Joana P N; Segundo, Marcela A; Reis, Salette; Lima, José L F C

2009-09-15

235

A nonlinear correlation method using multiphoton ionization for the measurement of uv ultrashort pulses  

Microsoft Academic Search

A new nonlinear correlation method which makes it possible to measure the duration of uv ultrashort pulses has been proposed. In this method the multiphoton ionization of gases is used as a nonlinear process and the ion current caused by the process is detected. We have also experimentally demonstrated its usefulness in the uv region by observing the second- and

N. Morita; T. Yajima

1982-01-01

236

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

PubMed

Second derivative ultra-violet spectrophotometric methods are described for the measurement of nitrate and total nitrogen in freshwaters using flow analysis techniques. A simple flow system consisting of a peristaltic pump and a single-reflection flow-through cell was used for the measurement of nitrate. Quantification of total nitrogen using alkaline peroxodisulfate photo-digestion was achieved by incorporating an ultra-violet photo-reactor, a hollow-fibre filter and a debubbler into the flow system. The nitrate system featured a limit of detection of 0.04 mg N L(-1), 0.4%RSD (1 mg N L(-1) as nitrate, n=10), a coefficient of determination (R(2)) of 0.9995 over the calibration range 0.0-2.0 mg N L(-1), and a data acquisition time of 1.5s per spectrum. The total nitrogen system featured a limit of detection of 0.05 mg N L(-1), 1%RSD (1 mg N L(-1) as ammonium chloride, n=10), a coefficient of determination of 0.9989 over the calibration range 0.0-2.0 mg N L(-1), and a throughput of 5 sample h(-1) measured in triplicate. Digestions of five model nitrogen compounds returned recoveries of >88%. Determinations carried out using the developed systems show a high degree of agreement with data obtained using reference methods. These methods require no colorimetric reagents and eliminate the requirement for a toxic cadmium reduction column. The overlap of chloride and nitrate spectra in seawater is not eliminated entirely by the use of second derivative spectrophotometry, and consequently the methods are restricted to the analysis of freshwaters. PMID:21907028

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

2011-10-17

237

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

238

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

239

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

240

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

PubMed

Three simple and sensitive methods for the assay of Nifurtimox (NIF) which is an active antitrypanocide were developed. These methods are based on the formation of coloured species by treating either its reduction product with 3-methyl-2-benzothiazolinone hydrazone (MBTH) in the presence of ferric chloride (method A) or its hydrolysis product with 2-thiobarbituric acid (TBA) (method B) or by oxidizing it with excess N-bromosuccinamide (NBS) and determining the consumed NBS using p-N-methylaminophenol sulphate (metol)-isonicotinic acid hydrazide (INH) (method C). All variables have been optimized and the reaction mechanisms presented. Regression analysis of Beer's plot showed good correlation in the concentration range of 2.5-10, 2.5-30 and 1.25-7.5 microg/ml for methods A, B and C, respectively. No interference was observed from the additives and the validity of the methods was tested by analysing the tablets. Recoveries were 99.2-100.9%. PMID:18966156

Sastry, C S; Rao, K R; Krishna, D M; Sastry, B S; Prasad, D S

1994-11-01

241

Atomic absorption spectrophotometric methods for the determination of phosphorous and silicon in steel  

SciTech Connect

Several methods for the determination of phosphorus in steel by graphite furnace atomic absorption spectrophotometry (GFAA) have been put forth in the literature. The most promising of these procedures are evaluated and optimized parameters for this analysis are given. The methods evaluated are those involving zirconium carbide furnace tubes, chemical matrix modification with La, the use of the method of additions and calibration via NBS standards. Similarly, an overview of flame AA (FAA) methods for Si determination is given. An overall procedure is described which allows the GFAA determination of phosphorus (0.010 - 0.100%), with matrix modification using lanthanum and FAA determination of silicon (0.1 - 1%) and metal constituents in steel from a single sample dissolution using NBS steels as calibration standards.

McCarthy, J.P.; Nunn, E.B.; Kinard, C.

1983-01-01

242

Nanofiltration membrane prepared from cardo polyetherketone ultrafiltration membrane by UV-induced grafting method  

Microsoft Academic Search

Hydrophilic nanofiltration membranes were prepared by graft polymerization of hydrophilic monomers onto the surface of ultrafiltration membranes made from cardo polyetherketone (PEK-C). The method consists of a UV irradiation in the presence of acrylic for an in situ graft polymerization of polyacrylic acid (PAA) on the surface of the UF membranes. The effect of UV intensity, irradiation time and monomer

Changquan Qiua; Fan Xu; Quang Trong Nguyenb; Zhenghua Ping

243

Determination of antioxidant capacities of vegetable oils by ferric-ion spectrophotometric methods.  

PubMed

Two ferric-ion-based total antioxidant capacity methods: 1,10-phenanthroline (Phen) and ferric reducing antioxidant power (FRAP) were used for determination of antioxidant capacities (AC) of the acetonic and methanolic extracts of vegetable oils. The obtained mean Phen and FRAP values for acetonic extracts of olive oils, rapeseed, rice and four sunflower oils (39.3-336.5 and 39.5-339.6 micromol Fe/100g) were higher than for methanolic extracts (22.8-307.3 and 23.5-300.1 micromol Fe/100g). However, antioxidant capacities of methanolic extracts of corn oil, blended oils and two sunflower oils with garden green flowers (56.5-312.9 and 53.9-306.5 micromol Fe/100g for Phen and FRAP methods, respectively) were higher than for acetonic extracts of these oils (54.2-249.2 and 52.9-244.7 micromol Fe/100g for Phen and FRAP methods, respectively). There is a linear and significant correlation between these two analytical methods (r=0.9989 and 0.9986 for acetonic and methanolic extracts). Also, total phenolic compounds (TPC) in the studied oils correlated with their antioxidant capacities determined by Phen and FRAP methods (r=0.9012, 0.7818 and 0.8947, 0.7830 for acetonic and methanolic extracts, respectively). The comparable precision (R.S.D.=0.8-4.6%, 0.9-4.9% and 0.7-4.0%, 0.6-4.0% for acetonic and methanolic extracts, respectively) and sensitivity (epsilon=1.27 x 10(4), 1.11 x 10(4) and 2.62 x 10(4)dm(3)mol(-1)cm(-1)) for the proposed Phen and the modified FRAP methods, demonstrate the benefit of the Phen method in the routine analysis of antioxidant capacities of vegetable oils. PMID:18656676

Szyd?owska-Czerniak, Aleksandra; Dianoczki, Csilla; Recseg, Katalin; Karlovits, György; Sz?yk, Edward

2008-08-15

244

Simple and rapid spectrophotometric method for determination of adrenaline and isoprenaline.  

PubMed

A simple, rapid, and specific method for determination of adrenaline bitartrate and isoprenaline sulfate was developed. The method is based on the oxidation reaction in aqueous solution of either adrenaline bitartrate or isoprenaline sulfate in the presence of silver oxide to give a red aminochrome measurable at 490 nm. The color is stable for 2 h. Beer's law is valid within a concentration range of 5-80 micrograms/mL for each drug. All variables were studied to optimize the reaction conditions. The method is specific for catecholamine drugs having a secondary amine in the side chain. Other catecholamines such as orciprenaline and noradrenaline do not interfere, and no interference was observed in the presence of common pharmaceutical adjuvants. Interference due to sodium metabisulfite and sodium chloride was circumvented. The validity of the method was tested by analyzing adrenaline injections and isoprenaline tablets. Good recoveries were obtained for these preparations. The results were comparable to those obtained by official procedures. The proposed method is also recommended as a stability indicating assay for oxidative degradation of both drugs. PMID:3417596

el-Shabouri, S R; Hussein, S A; Abdel-Alim, A A

1988-01-01

245

Image-based detection of oligonucleotides--a low cost alternative to spectrophotometric or fluorometric methods.  

PubMed

Herein, we report a sensitive and low cost image-based (photocolorimetric) method for the detection of oligonucleotides on an activated polypropylene microtest plate (APP?TP). The assay was developed on the APP?TP by covalently immobilising 20-mer amino-modified oligonucleotides. Biotin-tagged complementary target sequences were then hybridised with the immobilised oligonucleotides. Colour was developed by streptavidin-HRP conjugate and the image of the coloured assay solution was taken by a desktop scanner and analysed using colour saturation. The developed method was analysed for its detection limit, accuracy, sensitivity and interference. The linearity range was found to be 1.7-170 ng mL(-1) while the lower limit of detection and limit of quantification were 1.7 and 5.6 ng mL(-1) respectively. The method showed comparable sensitivity to fluorometric methods, and was found to be correlated to fluorescence (R(2) = 0.8081, p-value < 0.0001) and absorbance (R(2) = 0.9394, p-value < 0.0001)-based quantification. It discriminates mismatched base sequences from perfectly matched sequences efficiently. Validation of the method was carried out by detecting por A DNA of Neisseria meningitidis in bacterial meningitis samples. The por A-specific probe having a 6-carbon spacer at its 5'-NH2 terminus was immobilised covalently to the APP?TP and hybridised with different samples of biotinylated single-stranded por A DNA. PMID:24653995

Ahirwar, Rajesh; Tanwar, Swati; Parween, Shahila; Kumar, Ashok; Nahar, Pradip

2014-05-01

246

New spectrophotometric methods for determination of captopril bulk drug and tablets.  

PubMed

Three simple, rapid and sensitive methods for the assay of captopril which is an effective alternative to digitalis were developed. These methods are based on the oxidation reaction in aqueous solution of captopril with either ferric chloride or iodine. The indirect quantitation of the product was carried out at 523, 351 and 620 nm for ferro-bipyridyl, residual iodine and residual iodine-starch complex, respectively. All variables were studied to optimize the reaction conditions. Regression analysis of Beer's plot showed good correlation in a general concentration range of 0.25-25 mug captopril/ml. No interference was observed from hydrochlorothiazide diuretic which was recently introduced in combination with captopril or other common pharmaceutical adjuvants. The validity of the methods was tested by analysing capoten and capozide tablets. Recoveries were 99.1-102.8%. PMID:18965276

Askal, H F

1991-10-01

247

An assessment of a simple spectrophotometric method for the determination of dissolved organic carbon in freshwaters  

Microsoft Academic Search

The ability of absorbance at 330 nm to predict dissolved organic carbon (DOC) concentration was tested on samples of throughfall, stem?flow, soil water, and stream water from the Maimai and Larry River catchments, Westland, New Zealand. Predictive ability for the combined samples was poor, but improved when the samples were split into groups of origin. For stream samples, the method

T. R. Moore

1987-01-01

248

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

NASA Astrophysics Data System (ADS)

A new analytical method using Back-Propagation (BP) artificial neural networks and spectrophotometry for simultaneous determination of calcium and magnesium in tap water, the Yellow River water and seawater is established. By condition experiment, the optimum analytical conditions for calcium, magnesium and Arsenazo (III) color reactions are obtained. Levenberg-Marquart (L-M) algorithm is used for calculation in BP neural network. The topological structure of three-layer BP ANN network architecture is chosen as 11-10-2 (nodes). The initial value of gradient coefficient ? is fixed at 0.001 and the increase factor and reduction factor of ? take the default values of the system. The data are processed by computers with our own programs written in MATLAB 7.0. The relative standard deviations of the calculated results for calcium and magnesium are 2.31% and 2.14%, respectively. The results of standard addition method show that the recoveries of calcium and magnesium are 103.6% and 100.8% in the tap water, 103.2% and 96.6% in the Yellow River water (Lijin district of Shandong Province), and 98.8%-103.3% and 98.43%-103.4% in seawater from Jiaozhou Bay of Qingdao. It is found that 14 common cations and anions do not interfere with the determination of calcium and magnesium under the optimum experimental conditions. The comparative experiments do not show any obvious difference between the results obtained by this new method and those obtained by the classical complexometric titration method in seawater medium. This method exhibits good reproducibility and high accuracy in the determination of calcium and magnesium and can be used for the simultaneous determination of Ca2+ and Mg2+ in tap water and natural water.

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

2010-09-01

249

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

SciTech Connect

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

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

1986-06-01

250

Simultaneous spectrophotometric determination of four metals by two kinds of partial least squares methods  

Microsoft Academic Search

Simultaneous determination of Ni(II), Cd(II), Cu(II) and Zn(II) was studied by two methods, kernel partial least squares (KPLS) and wavelet packet transform partial least squares (WPTPLS), with xylenol orange and cetyltrimethyl ammonium bromide as reagents in the medium pH=9.22 borax-hydrochloric acid buffer solution. Two programs, PKPLS and PWPTPLS, were designed to perform the calculations. Data reduction was performed using kernel

Ling Gao; Shouxin Ren

2005-01-01

251

Determination of antioxidant capacities of vegetable oils by ferric-ion spectrophotometric methods  

Microsoft Academic Search

Two ferric-ion-based total antioxidant capacity methods: 1,10-phenanthroline (Phen) and ferric reducing antioxidant power (FRAP) were used for determination of antioxidant capacities (AC) of the acetonic and methanolic extracts of vegetable oils. The obtained mean Phen and FRAP values for acetonic extracts of olive oils, rapeseed, rice and four sunflower oils (39.3–336.5 and 39.5–339.6?mol Fe\\/100g) were higher than for methanolic extracts

Aleksandra Szyd?owska-Czerniak; Csilla Dianoczki; Katalin Recseg; György Karlovits; Edward Sz?yk

2008-01-01

252

Quality Assessment of Heated Cooking Oil, Agab, Using a Simple Newly-Developed Spectrophotometric Method  

Microsoft Academic Search

Deep fat frying is one of the most widely used cooking practices but heat treatment produces many degradation products, some\\u000a of which may cause health hazards. A simple, rapid, and inexpensive method for assessment of the quality of cooking oil used\\u000a for frying was developed using a spectrophotometer. Potato slices were heated in Agab oil (soybean\\/sunflower:1\\/l volume) at\\u000a 180 ± 5 °C for

Said Fatouh Hamed; Ghada Ahmed abo El-Wafa; Ahmed El-Ghorab; Takayuki Shibamoto

253

Derivative spectrophotometric method for estimation of antiretroviral drugs in fixed dose combinations.  

PubMed

Purpose: Lamivudine is cytosine and zidovudine is cytidine and is used as an antiretroviral agents. Both drugs are available in tablet dosage forms with a dose of 150 mg for LAM and 300 mg ZID respectively. Method: The method employed is based on first order derivative spectroscopy. Wavelengths 279 nm and 300 nm were selected for the estimation of the Lamovudine and Zidovudine respectively by taking the first order derivative spectra. The conc. of both drugs was determined by proposed method. The results of analysis have been validated statistically and by recovery studies as per ICH guidelines. Result: Both the drugs obey Beer's law in the concentration range 10-50 ?g mL-1,for LAM and ZID; with regression 0.9998 and 0.9999, intercept - 0.0677 and - 0.0043 and slope 0.0457 and 0.0391 for LAM and ZID, respectively.The accuracy and reproducibility results are close to 100% with 2% RSD. Conclusion: A simple, accurate, precise, sensitive and economical procedures for simultaneous estimation of Lamovudine and Zidovudine in tablet dosage form have been developed. PMID:24312779

P B, Mohite; R B, Pandhare; S G, Khanage

2012-01-01

254

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

255

Spectrophotometric Determination of Uranium Using Quercetin.  

National Technical Information Service (NTIS)

A spectrophotometric method for quantitative determination of uranium, using a flavone (quercetin) as complexing agent, is described. The method is based on the reaction between uranyl ion and alcoholic solution of quercetin with a complex formation of in...

A. R. Barros

1972-01-01

256

Comparison of visual and spectrophotometric methods of MIC endpoint determinations by using broth microdilution methods to test five antifungal agents, including the new triazole D0870.  

PubMed Central

A study to compare three different methods for reading MIC endpoints tested by the broth microdilution modification of the National Committee for Clinical Laboratory Standards (Villanova, Pa.) reference method was conducted. MICs of amphotericin B, flucytosine, fluconazole, itraconazole, and a new triazole, D0870, were determined for five reference yeast strains and 100 clinical isolates of Candida spp. MICs were read visually according to National Committee for Clinical Laboratory Standards guidelines from microdilution trays that had been (VS) and had not been (V) shaken. MICs were also determined spectrophotometrically (SP) at 492 nm. SP endpoints were determined as the concentrations resulting in a > or = 50% inhibition of growth (flucytosine and azoles) and a > or = 90% inhibition of growth (amphotericin B) relative to control growth. The five reference strains were tested nine times each against all five antifungal agents, and the MIC results for each reading method were compared with a 3-log2 dilution reference range determined by the macrodilution (M27-P) method. Overall, 84 to 100% of the MICs determined by V, 93 to 100% of those determined by VS, and 89 to 100% of those determined by SP fell within the 3-log2 dilution reference range for each reference strain and antifungal agent. Reproducibility was 99% for V and SP and 98% for VS. Agreement among the three methods of reading ranged from 97 to 99%. Excellent agreement among reading methods was also observed for all antifungal agents when tested against 100 clinical isolates.(ABSTRACT TRUNCATED AT 250 WORDS)

Pfaller, M A; Messer, S A; Coffmann, S

1995-01-01

257

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

PubMed

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

Chen, Jing; Chen, Jianhua; Zhou, Changlin

2008-01-01

258

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).

Turak, Fatma; Dinc, Mithat; Dulger, Oznur; Ozgur, Mahmure Ustun

2014-01-01

259

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

260

[Application of the chromatographic-spectrophotometric method for the analytical control of l-ascorbic acid in pharmaceutical and plant material].  

PubMed

The conditions of chromatographic separation allowing the isolation of L-ascorbic acid from its products of decomposition and other accompanying substances in the determined pharmaceutic preparation and plant materials were established. The isolated L-ascorbic acid was signed by the extractive--spectrophotometric method using coupled redox-complexation reactions with iron(III), 1, 10 phenantroline and bromophenol blue system. The analytical procedure allowing the evaluation of durability of vitamin C in multivitamin "Vitaral" preparate was described. The procedure was used also for the evaluation of the loss of L-ascorbic acid in the parsley and lovage in the process of drying and storage. PMID:10846938

Hachu?a, U; Zawisza, B; Winkler, W

2000-01-01

261

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

262

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

263

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

PubMed Central

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

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

2012-01-01

264

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; Borrás, Carlos; Mostany, Jorge; Scharifker, Benjamin R

2010-02-01

265

Removal of organic matter from a variety of water matrices by UV photolysis and UV/H2O2 method.  

PubMed

A re-circulated flow-through photoreactor was used to evaluate the ultraviolet (UV) photolysis and UV/H(2)O(2) oxidation process in the purification of three different water matrices. Chemically coagulated and electrocoagulated surface water, groundwater contaminated with creosote wood preservative and 1,2-dichloroethane (DCE) containing washing water from the plant manufacturing tailor-made ion-exchange resins were used as sample waters. The organic constituents of creosote consist mainly of harmful polycyclic aromatic hydrocarbons (PAH) whereas 1,2-DCE is a toxic volatile organic compound (VOC). Besides analyzing the specific target compounds, total organic carbon (TOC) analysis and measurement of change in UV absorbance at 254 nm (UV(254)) were performed. Initial TOC, UV(254) and pH varied significantly among treated waters. Initial H(2)O(2) concentrations 0-200 mg/l were used. The UV/H(2)O(2) treatment was efficient in removing the hazardous target pollutants (PAHs and 1,2-DCE) and natural organic matter (NOM). In addition, high removal efficiency for TOC was achieved for coagulated waters and groundwater. Also, the efficiency of direct photolysis in UV(254) removal was significant except in the treatment of 1,2-DCE containing washing water. Overall, UV(254) and TOC removal rates were high, except in case of washing water, and the target pollutants were efficiently decomposed with the UV/H(2)O(2) method. PMID:20381240

Vilhunen, Sari; Vilve, Miia; Vepsäläinen, Mikko; Sillanpää, Mika

2010-07-15

266

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

PubMed

Different spectrophotometric and HPTLC-densitometric methods are presented for the simultaneous determination of lisinopril and hydrochlorothiazide in pharmaceutical tablets. The spectrophotometric methods include third derivative (3D) ultraviolet spectrophotometry with zero crossing measurement at 217.4 and 233.4 nm, second derivative of the ratio spectra with measurement at 214.3 and 228.0 nm; both classical least squares and principal component regression were applied to the UV absorption and first derivative spectra of the mixture. The HPTLC method was based on separation of both drugs followed by densitometric measurements of their spots at 210 and 275 nm for lisinopril and hydrochlorothiazide, respectively. The separation was carried out on Merck HPTLC aluminum plates of silica gel 60 F254, using chloroform-ethylacetate-acetic acid (10:3:2 by vol.) as mobile phase. The linear and second order polynomial were used for the regression equation of lisinopril and hydrochlorothiazide, respectively. PMID:11377075

El-Gindy, A; Ashour, A; Abdel-Fattah, L; Shabana, M M

2001-07-01

267

Simplified spectrophotometric method using methylene blue for determining anionic surfactants: applications to the study of primary biodegradation in aerobic screening tests.  

PubMed

In the present work, we propose a simplified spectrophotometric method for determining anionic surfactants, based on the formation of the ionic pair anionic surfactant-methylene blue (AS-MB). This method, in relation to the conventional analytic procedure, considerably reduces not only the quantity of chloroform used in extracting the ionic pair formed, but also the time and the quantity of sample necessary to perform the assay, eliminating the filtration stage. The method has been simplified by displacing the transfer equilibrium of the ionic pair AS-MB towards the organic phase, augmenting the volumetric relationship of chloroform/sample. The method proposed has been applied in the study of primary biodegradation kinetics of linear alkylbenzenesulfonate (LAS). PMID:16616296

Jurado, E; Fernández-Serrano, M; Núńez-Olea, J; Luzón, G; Lechuga, M

2006-10-01

268

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

PubMed

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

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

2014-09-15

269

Spectrophotometric determination of hydrazine.  

PubMed

Hydrazine is determined spectrophotometrically by forming the derivative 2,4-dinitrophenylhydrazine from 2,4-dinitrochlorobenzene. The formed dinitro derivative undergoes condensation reaction to form the hydrazone with p-dimethylaminobenzaldehyde (p-DAB). The resulting yellow colored product is stable in acidic medium and has a maximum absorption at 458 nm. The colour system obeys Beer's law in the range 0-7 microg of hydrazine in an overall volume of 25 mL. The molar absorptivity is calculated to be 8.1 x 10(4) L mol(-1)cm(-1) with a correlation coefficient of 0.998. The relative standard deviation is 1.7% (n=10) at 6 microg of hydrazine. Interferences due to foreign ions have been studied and the method has been applied for the determination of hydrazine in boiler feed water. PMID:18371842

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

2008-03-15

270

Solidphase ultraviolet absorbance spectrophotometric multisensor for the simultaneous determination of butylated hydroxytoluene and co-existing antioxidants  

Microsoft Academic Search

Continuous flow injection and UV spectrophotometric detection have been proposed for simultaneous determination of the two binary mixtures, butylated hydroxytoluene (BHT)\\/n-propyl gallate (n-PG) and butylated hydroxytoluene (BHT)\\/butylated hydroxyanisole (BHA), in food and cosmetics samples. The method is based on the different residence times of each antioxidant when the flow cell is packed to a height of 25mm with silica C18

L. F. Capitán-Vallvey; M. C. Valencia; E. Arana Nicolás

2004-01-01

271

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

PubMed

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

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

2014-07-15

272

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

273

Pyrocatechol violet in pharmaceutical analysis. Part I. A spectrophotometric method for the determination of some beta-lactam antibiotics in pure and in pharmaceutical dosage forms.  

PubMed

A fairly sensitive, simple and rapid spectrophotometric method for the determination of some beta-lactam antibiotics, namely ampicillin (Amp), amoxycillin (Amox), 6-aminopenicillanic acid (6APA), cloxacillin (Clox), dicloxacillin (Diclox) and flucloxacillin sodium (Fluclox) in bulk samples and in pharmaceutical dosage forms is described. The proposed method involves the use of pyrocatechol violet as a chromogenic reagent. These drugs produce a reddish brown coloured ion pair with absorption maximum at 604, 641, 645, 604, 649 and 641 nm for Amp, Amox, 6APA, Clox, Diclox and Flucolx, respectively. The colours produced obey Beer's law and are suitable for the quantitative determination of the named compounds. The optimization of different experimental conditions is described. The molar ratio of the ion pairs was established and a proposal for the reaction pathway is given. The procedure described was applied successfully to determine the examined drugs in dosage forms and the results obtained were comparable to those obtained with the official methods. PMID:11409329

Amin, A S

2001-03-01

274

Application of a UV–vis detection-HPLC method for a rapid determination of lycopene and ?-carotene in vegetables  

Microsoft Academic Search

The purpose of this paper is to optimize an HPLC method for the determination of lycopene and ?-carotene in vegetables and compare it with a spectrophotometric standard method. Among the different conditions studied the most suitable ones for our samples were: extraction with hexane\\/acetone\\/ethanol (50:25:25 v\\/v\\/v), evaporation of the hexane layer, dissolution of the dry extract in THF\\/ACN\\/methanol (15:30:55 v\\/v\\/v)

A. I. Olives Barba; M. Cámara Hurtado; M. C. Sánchez Mata; V. Fernández Ruiz; M. López Sáenz de Tejada

2006-01-01

275

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

276

Determination of the relative contribution of quercetin and its glucosides to the antioxidant capacity of onion by cyclic voltammetry and spectrophotometric methods.  

PubMed

This paper describes the use of cyclic voltammetry (CV), spectrophotometric methods [Trolox equivalent antioxidant capacity (TEAC), peroxyl radical trapping capacity (PRTC), DPPH radical scavenging activity (RSA), and Folin-Ciocalteu reagent (FCR) reducing capacity], and photochemiluminescence (PCL) for the measurement of the antioxidant capacity of onion var. Sochaczewska and var. Szalotka. The antioxidant and reducing activity of the dominant onion flavonoids quercetin (Q), quercetin-3- O-beta-glucoside (Q3G), quercetin-4'- O-beta-glucoside (Q4'G), and quercetin-3,4'-di- O-beta-glucoside (Q3,4'G) were determined by spectrophotometric (TEAC and PRTC) and CV methods, respectively. The contribution of quercetin and its glucosides to the antioxidant capacity of onion was calculated in consequence of the qualitative and quantitative analysis of onion flavonoids by high-performance liquid chromatography-ultraviolet-mass spectrometry. The dominant forms of quercetin in the onion var. Sochaczewska and Szalotka included Q4'G (61 and 54%), Q3,4'G (37 and 44%), Q3G (1.4 and 1.1%), and free quercetin (1.1 and 0.7%), respectively. The CV experiment showed the highest reducing activity of Q while Q3G, Q4'G, and Q3,4'G exhibited about 68, 51, and 30% of the reducing power noted for Q. The order of the reducing activity of onion flavonoids was confirmed by their free radical scavenging activity and evaluated by TEAC and PRTC assays as follows: Q > Q3G > Q4'G > Q3,4'G. The Q4'G and Q3,4'G showed poor antioxidant activity under both applied spectrophotometric assays but still exhibited reducing activity based on CV experiments. The reducing capacity of onions determined by CV method was twice higher than the antioxidant capacity formed by water-soluble compounds (ACW) evaluated by PCL, and it was about 50% higher than PRTC and DPPH RSA results and the converted FCR reducing capacity. In contrast, the reducing capacity of onions determined by the CV method was 3-fold and about four times lower when compared to the antioxidant capacity evaluated by the TEAC method and that formed by lipid-soluble compounds (ACL) provided by PCL, respectively. The highest antioxidant capacity of onion was found under cumulative consideration of PCL (ACW + ACL) and TEAC assays. The relative contribution of Q and its glucosides to the antioxidant capacity of onions showed a low contribution of Q, Q3G, and Q3,4'G derived from CV, TEAC, and PRTC assays while the highest contribution to the antioxidant capacity of onions was provided by Q4'G. PMID:18454541

Zielinska, Danuta; Wiczkowski, Wieslaw; Piskula, Mariusz Konrad

2008-05-28

277

The development of spectrophotometric and electroanalytical methods for ascorbic acid and acetaminophen and their applications in the analysis of effervescent dosage forms.  

PubMed

The electroanalytical study of ascorbic acid, acetaminophen and of several mixtures of these compounds in different ratios has been made by using a carbon paste electrode (CPE-graphite:solid paraffin 2:1) as working electrode and an Ag/AgCl reference electrode. The potential curves were recorded using different concentrations of ascorbic acid and acetaminophen by measuring samples between 10 and 50 microl. The oxidation reactions were studied in a potential range from -0.1 to +1.3 V with different sweep rates, at different current sensitivities, in stationary working conditions and stirring before each replicate. The oxidation of ascorbic acid occurs at +0.31 +/- 0.02 V and the oxidation of acetaminophen at +0.60 +/- 0.05 V; meanwhile, the current has a linear variation for the following concentration ranges: 10(-3)-10(-2) M for the ascorbic acid and 3 x 10(-6)-7.5 x 10(-3) M for acetaminophen (r2 = 0.999 for both ascorbic acid and acetaminophen). The mixtures of ascorbic acid and acetaminophen were made as follows: 1:1, 1:2, 1:3, 2:1, and 3:1. The studies revealed the alteration of the voltammograms processed according to the validation methodology. The best potential variation range for different current sensitivities, the influence of the sweep rate, of the solvent volume and of the pH were studied. The mutual interferences of the compounds in the mixtures and the electroactive compounds in the pharmaceutical dosage forms, especially effervescent ones, also made the object of the research. The same mixtures were studied using the direct spectrophotometric method that revealed a lot of spectral interferences. In order to solve this problem, an appropriate separation or an indirect spectrophotometric method (the apparent content curves method) were used. The spectrophotometric and voltammetric methods developed were used to determine ascorbic acid and acetaminophen in different dosage forms (vials, tablets, suppositories and effervescent dosage forms). The results were compared with those obtained by other techniques. PMID:10898157

S?ndulescu, R; Mirel, S; Oprean, R

2000-08-01

278

Spectrophotometric Determination of Steroid Oximes  

Microsoft Academic Search

A spectrophotometric procedure for the determination of steroid oximes is described utilizing 11?-hydroxy-iia-methyl-5?-pregnane -3, 20 -dione dioxime (I) and iia-hydroxy-progesterone dioxime (II) as models. The method is based on (a) acid hydrolysis to release hydroxylamine, (b) oxidation of hydroxylamine to nitrous acid with iodine, (c) diazotization of sulfanilic acid with the nitrous acid, (d) coupling of the diazonium compound with

Arlington A. Forist; Ray W. Judy

1974-01-01

279

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  

Microsoft Academic Search

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 840nm in the phosphate concentration range,

B. Shyla; Mahadevaiah; G. Nagendrappa

2011-01-01

280

Experimental Study of Fault Arc Protection Based on UV Pulse Method in High Voltage Switchgear  

NASA Astrophysics Data System (ADS)

Based on the relationship between electrical equipment discharge and ultraviolet radiation, this paper proposed the use of UV pulse method to detect switchgear arcing faults. Switchgear protection system based on this new technique detects arcing faults by analyzing the ultraviolet produced by electric arc. This technique was implemented and tested in laboratory, and the performance of the protection module was verified: it is capable of calculating the number of UV pulses quickly and precisely, which indicates the intensity of fault arc, and therefore it can be applied to arcing faults protection system for detecting faults.

Wang, Jingang; Xu, Cheng; Sun, Jiaxiang

2014-06-01

281

Determination of pKa of felodipine using UV-Visible spectroscopy  

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

282

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

PubMed

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

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

2013-11-01

283

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

PubMed Central

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

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

2014-01-01

284

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

PubMed

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

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

2014-01-01

285

Simultaneous determination of Allura Red and Ponceau 4R in drinks with the use of four derivative spectrophotometric methods and comparison with high-performance liquid chromatography.  

PubMed

Four simple, rapid, sensitive, and accurate spectrophotometric methods were developed for the simultaneous determination of Allura Red (AR) and Ponceau 4R (P) without previous chemical separation. The first method, derivative spectrophotometry, depends on first derivative spectrophotometry with zero-crossing and peak-to-base measurement. The second method, derivative ratio spectrophotometry, uses the first derivative of the ratio spectra. The ratio spectra are obtained by dividing the absorption spectra of a binary mixture by that of one of the components. The third method, differential derivative spectrophotometry, is based on the measurement of the difference absorptivities derivatized in the first order of a sample extract in 0.1 M NaOH relative to that of an equimolar solution in 0.1 M HCl. The fourth method, based on the compensation technique, is presented for the derivative spectrophotometric determination of binary mixtures with overlapping spectra by using ratios of the derivative maximum or minimum; the exact compensation of either component in the mixture can be achieved, followed by its determination. All the proposed methods were successfully applied to the determination of the colorants in their laboratory mixtures and granulated drinks without any interference by the ingredients. AR and P showed good linearity, with regression coefficients of 0.9994-0.9999. The LOD and LOQ values ranged from 0.059 to 0.102 and 0.198 to 0.341 microg/mL, respectively. The intraday and interday precision tests produced good RSD values (<1.37%); recoveries ranged from 98.75 to 100.37% for all four methods. The common ingredients and additives did not interfere in the AR and P determination. The results of the proposed methods were statistically compared with the results of an HPLC method given in the literature (Nordic Committee on Food Analysis; NMKL 130) at the 95% confidence level by Student's test and the variance ratio F-test. No statistically significant difference was found among these methods. PMID:24645518

Turak, Fatma; Ozgur, Mahmure Ustun

2013-01-01

286

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

PubMed

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. PMID:24934969

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

2014-12-10

287

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

288

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

PubMed

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

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

2011-12-15

289

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

290

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 Inęs G S; Estela, José Manuel; Segundo, Marcela A; Cerdŕ, Víctor

2011-06-15

291

Novel spectrophotometric method for the quantitation of urinary xanthurenic acid and its application in identifying individuals with hyperhomocysteinemia associated with Vitamin B? deficiency.  

PubMed

A novel spectrophotometric method for the quantification of urinary xanthurenic acid (XA) is described. The direct acid ferric reduction (DAFR) procedure was used to quantify XA after it was purified by a solid-phase extraction column. The linearity of proposed method extends from 2.5 to 100.0?mg/L. The method is precise, yielding day-to-day CVs for two pooled controls of 3.5% and 4.6%, respectively. Correlation studies with an established HPLC method and a fluorometric procedure showed correlation coefficients of 0.98 and 0.98, respectively. Interference from various urinary metabolites was insignificant. In a small-scale screening of elderly conducted at Penghu county in Taiwan (n = 80), we were able to identify a group of twenty individuals having hyperhomocysteinemia (>15? ? mole/L). Three of them were found to be positive for XA as analyzed by the proposed method, which correlated excellently with the results of the activation coefficient method for RBC's AST/B? functional test. These data confirm the usefulness of the proposed method for identifying urinary XA as an indicator of vitamin B? deficiency-associated hyperhomocysteinemic condition. PMID:24151616

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

2013-01-01

292

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

293

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

PubMed Central

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

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

2013-01-01

294

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

PubMed

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. PMID:23807049

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

2013-10-01

295

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

PubMed

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

296

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.

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

2013-01-01

297

Extractive Spectrophotometric Determination of Ambrisentan  

PubMed Central

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

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

2013-01-01

298

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

299

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

300

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

PubMed

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

Liu, Xiangxuan; Liang, Jiantao; Wang, Xuanjun

2011-05-01

301

Sustained prediction ability of net analyte preprocessing methods using reduced calibration sets. Theoretical and experimental study involving the spectrophotometric analysis of multicomponent mixtures.  

PubMed

A newly developed multivariate method involving net analyte preprocessing (NAP) was tested using central composite calibration designs of progressively decreasing size regarding the multivariate simultaneous spectrophotometric determination of three active components (phenylephrine, diphenhydramine and naphazoline) and one excipient (methylparaben) in nasal solutions. Its performance was evaluated and compared with that of partial least-squares (PLS-1). Minimisation of the calibration predicted error sum of squares (PRESS) as a function of a moving spectral window helped to select appropriate working spectral ranges for both methods. The comparison of NAP and PLS results was carried out using two tests: (1) the elliptical joint confidence region for the slope and intercept of a predicted versus actual concentrations plot for a large validation set of samples and (2) the D-optimality criterion concerning the information content of the calibration data matrix. Extensive simulations and experimental validation showed that, unlike PLS, the NAP method is able to furnish highly satisfactory results when the calibration set is reduced from a full four-component central composite to a fractional central composite, as expected from the modelling requirements of net analyte based methods. PMID:11478644

Goicoechea, H C; Olivieri, A C

2001-07-01

302

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

Microsoft Academic Search

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

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

1998-01-01

303

Theoretical study of UV spectra of diazaphenanthrenesulfonamides calculated by AM1 and DFT B3-LYP methods  

NASA Astrophysics Data System (ADS)

Two diazaphenanthrenesulfonamides have been synthesized. For calculation of experimental and theoretical UV values of these compounds the AM1 CI method has been used; their geometry optimisation was made with AM1 CI and DFT B-3 LYP methods.

Dondela, Barbara; Chrzastek, Lidia

2007-08-01

304

Theoretical study of UV spectra of diazaphenanthrenesulfonamides calculated by AM1 and DFT B3-LYP methods  

Microsoft Academic Search

Two diazaphenanthrenesulfonamides have been synthesized. For calculation of experimental and theoretical UV values of these compounds the AM1 CI method has been used; their geometry optimisation was made with AM1 CI and DFT B-3 LYP methods.

Barbara Dondela; Lidia Chrzastek

2007-01-01

305

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

PubMed Central

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

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

2007-01-01

306

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

SciTech Connect

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

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

1998-12-01

307

Development of a dispersive liquid-liquid microextraction method for spectrophotometric determination of barbituric acid in pharmaceutical formulation and biological samples.  

PubMed

In this paper, a novel and simple method for the determination of trace amounts of barbituric acid in water and biological samples was developed by using dispersive liquid-liquid microextraction (DLLME) techniques combined with spectrophotometric analysis. The procedure is based on color reaction of barbituric acid with p-dimethylaminobenzaldehyde and extraction of the color product using the DLLME technique. Some important parameters such as reaction conditions and the type and volume of extraction and dispersive solvents as well as the extraction time were investigated and optimized in detail. Under the optimum conditions, the calibration graphs were linear over the range of 5.0 to 200 ng ml(-1) with limit of detection of 2.0 ng ml(-1). Relative standard deviation for five replicate determinations of barbituric acid at 50 ng ml(-1) concentration level was calculated to be 1.64%. Average recoveries for spiked samples were determined to be between 94% and 105%. The proposed method was applied for the determination of barbituric acid in pharmaceutical formulation and biological samples. PMID:21303651

Zarei, Ali Reza; Gholamian, Forouzan

2011-05-15

308

Spectrophotometric method for the determination of sorbic acid in various food samples with iron(III) and 2-thiobarbituric acid as reagents.  

PubMed

A simple, rapid and accurate spectrophotometric method has been developed for the determination of sorbic acid in various food samples based on the oxidation of sorbic acid by iron(III) at 100 degrees C to malonaldehyde, which then reacts with 2-thiobarbituric acid to form a reddish brown product. The optimum experimental conditions for colour development have been assessed. Absorbance measurements were made at 529 nm in the presence of 0.4% m/V citric acid. The calibration graph was linear for 0-6 micrograms ml-1 of sorbic acid with a slope of 0.131 A micrograms-1 ml. The recoveries of sorbic acid at concentrations of 164-557 micrograms ml-1 ranged from 96 to 103%. The relative standard deviations of ten replicate determinations of sorbic acid in a synthetic cream soda sample spiked with 573 micrograms ml-1 of sorbic acid and in an onion juice sample containing 82 micrograms ml-1 of sorbic acid were 1.6 and 1.9%, respectively. Interferences from several common food additives can be minimised by extracting sorbic acid with diethyl ether and then back-extracting the acid with sodium hydrogen carbonate. The method has been applied successfully to the determination of sorbic acid in a wide range of food samples including beverages, cake, cake mate, garlic bread sprinkle, onion juice, oyster flavoured sauce and grenadine syrup. PMID:2712320

Lau, O W; Luk, S F; Lam, R K

1989-02-01

309

Simplest method for creating micropatterned nanostructures on PDMS with UV light.  

PubMed

The fabrication of micropatterned structures on PDMS is a critical step in soft lithography, microfluidics, and many other PDMS-based applications. To substitute traditional mold-casting methods, we develop a simple method to create micropatterned nanostructures on PDMS in one step. After exposing a flat PDMS surface to a UV pen lamp through a photomask (such as a TEM grid), micropatterned nanostructures can be formed readily on the PDMS surface. We also demonstrate that fabricated PDMS can be used for the microcontact printing of protein immunoglobulin (IgG) on solid surfaces. This method is probably the simplest method of creating micropatterned nanostructures on PDMS reported so far because it does not need casting, surface coating, or chemical reagents. Only a UV pen lamp and a photomask are required, and this method can be performed under ambient conditions without vacuum. We expect that this method will greatly benefit researchers who use PDMS regularly in various applications such as soft lithography and microfluidics. PMID:21981448

Xue, Chang-Ying; Zhang, Wei; Choo, Wan Hui Stella; Yang, Kun-Lin

2011-11-15

310

An improved UHPLC-UV method for separation and quantification of carotenoids in vegetable crops.  

PubMed

Carotenoid identification and quantitation is critical for the development of improved nutrition plant varieties. Industrial analysis of carotenoids is typically carried out on multiple crops with potentially thousands of samples per crop, placing critical needs on speed and broad utility of the analytical methods. Current chromatographic methods for carotenoid analysis have had limited industrial application due to their low throughput, requiring up to 60min for complete separation of all compounds. We have developed an improved UHPLC-UV method that resolves all major carotenoids found in broccoli (Brassica oleracea L. var. italica), carrot (Daucus carota), corn (Zea mays), and tomato (Solanum lycopersicum). The chromatographic method is completed in 13.5min allowing for the resolution of the 11 carotenoids of interest, including the structural isomers lutein/zeaxanthin and ?-/?-carotene. Additional minor carotenoids have also been separated and identified with this method, demonstrating the utility of this method across major commercial food crops. PMID:25038701

Maurer, Megan M; Mein, Jonathan R; Chaudhuri, Swapan K; Constant, Howard L

2014-12-15

311

Minor polar compounds in extra virgin olive oil: correlation between HPLC-DAD-MS and the Folin-Ciocalteu spectrophotometric method.  

PubMed

Minor polar compounds of 88 extra virgin olive oils were analyzed by HPLC-DAD-MS (high-performance liquid chromatography-diode array detector-mass spectrometry) and by the Folin-Ciocalteu (FC) spectrophotometric method, to validate and evaluate, for olive oils, the linear association between FC and HPLC data. The Pearson correlation coefficients were calculated between HPLC and FC results. The highest, positive R were related with deacetoxyoleuropein aglycone (R = 0.93) and oleuropein aglycone (R = 0.93) as single compounds and with the sum of orthodiphenols (R = 0.94) and the sum of all compounds (R = 0.95), showing that both estimations of total phenols content are reliably correlated, regardless for the absolute contents and are independent of the relative composition of the phenolic fraction. On the other hand the HPLC quantifications of apigenin and lignans showed no significant correlation with FC. These results, supported also by principal component analysis, may suggest caution about the interpretation of FC results to compare olive oils with very different phenolic profiles. PMID:24405086

Alessandri, Stefano; Ieri, Francesca; Romani, Annalisa

2014-01-29

312

A simple spectrophotometric method for the determination of cobalt in industrial, environmental, biological and soil samples using bis(salicylaldehyde)orthophenylenediamine.  

PubMed

Bis(salicylaldehyde)orthophenylenediamine (BSOPD) has been proposed as new analytical reagent for the direct non-extractive spectrophotometric determination of cobalt. It reacts with cobalt in slightly acidic (0.0002-0.001 M H(2)SO(4)) 50% 1,4-dioxanic medium to form a red-orange chelate with a molar ratio 1:1. The reaction is instantaneous and the maximum absorbance was obtained at 458 nm and remains constant for over 24h. The average molar absorption coefficient and Sandell's sensitivity were found to be 1.109 x 10(4)l mol(-1)cm(-1) and 20 ng cm(-2) of Co(II), respectively. Linear calibration graph was obtained for 0.1-15 mg l(-1) of Co(II) with a correlation coefficient value of 0.995 for Co-BSOPD complex. Large excess of 44 cations, anions and complexing agents do not interfere in the determination. The method was successfully used in the determination of cobalt(II) from synthetic mixture and certified reference materials for the purpose of validating the method and the results of analyses were found to be excellent agreement with those of actual values. This developed method was also used for determination of cobalt in some environmental waters (potable and polluted), biological (blood and urine) and soil samples and solution containing both cobalt(II) and cobalt(III). The results of the proposed method for biological samples were comparable with AAS and were found to be in good agreement. The method has high precision and accuracy (s=+/-0.01 for 0.5 mg l(-1)). PMID:17215023

Ahmed, M Jamaluddin; Uddin, M Nasir

2007-05-01

313

Determination of ambroxol hydrochloride in tablets using flow-injection UV spectrophotometry and HPLC  

Microsoft Academic Search

A flow-injection UV spectrophotometric method was developed for the determination of ambroxol hydrochloride in tablets. The\\u000a quantitative determination of ambroxol was performed at 245 nm using distilled water as the carrier solvent. In this study,\\u000a the flow rate, loop volume, and the number of injections per hour were 15 mL\\/min, 193 ?L, and 100, respectively. The analytical\\u000a signal of ambroxol

E. Satana; H. Basan; N. G. Go?er

2008-01-01

314

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

NASA Astrophysics Data System (ADS)

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

Zhou, Zhengwei; Jiang, Jia Qian

2012-07-01

315

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

PubMed Central

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

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

2013-01-01

316

Catalasic activity in fish liver: improvement of the UV to visible analytic method.  

PubMed

Antioxidative defenses and more especially catalasic activity (CAT) are studied in a large range of scientific research thematics. In environmental sciences, the problematic of oxidative stress is of great interest as pollutants can induce perturbations of redox homeostasis. Consequently, changes in antioxidative defenses levels in fish tissues and particularly in liver are used as potential biomarkers of pollution. In most studies, the CAT was assayed by following during 5 min the consumption of H2O2 in cytosolic buffered extracts at 240 nm (UV-method). This study proposed a development of this method in the visible, using permanganate and a 525-nm detection, which was more accurate, sensitive, and rapid. Moreover, the hepatic CAT of six different fish species [a cyclidae (Nimbochromis linni), 3 cyprinidae (Brachydanio rerio, Rutilus rutilus, Cyprinus carpio), an anguillidae (Anguilla anguilla), and a percidae (Perca fluviatilus)] was evaluated with the two protocols (UV- and KMnO4-method). The results but also the thermal optimum of the reaction and the interest of CAT as biomarker in ecotoxicology were discussed. PMID:23224832

Paris-Palacios, Séverine; Delahaut, Laurence; Carreras, Alexis; Thomas, Marielle; Biagianti-Risbourg, Sylvie

2013-08-01

317

?-Cyclodextrin cross-linked polymer as solid-phase extraction material coupled with the spectrophotometric method for the analysis of serum albumin  

NASA Astrophysics Data System (ADS)

The ?-cyclodextrin cross-linked polymer (?-CDCP) was synthesized and used as solid-phase extraction material to preconcentrate/analysis bovine serum albumin (BSA) coupled with UV-vis spectroscopy. The method based on the complex (BSA-phenylfluorone (PF)) adsorbed on ?-CDCP. Adsorption kinetics and various factors of the formation procedure of BSA-PF and its retention on ?-CDCP were investigated. The linear range and detection limit (DL) was 20.0-200.0 and 0.03 mg/L, respectively. Moreover, the ?-CDCP could be used repeatedly. The proposed method has been applied to analysis serum albumin with satisfactory results.

Wu, Min; Zhu, Xiashi

2010-12-01

318

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

PubMed Central

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

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

2013-01-01

319

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

PubMed

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

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

2010-01-01

320

Chromospheric Mass Motions during a Flare on Uv Ceti,  

National Technical Information Service (NTIS)

Simultaneous optical and IUE observations of a flare on UV Ceti in 1980 are reported. The IUE spectra show only slight increase of C IV line emission. The optical spectrophotometric observations show, from Balmer line profiles, turbulent broadening in qui...

K. J. H. Phillips G. E. Bromage P. L. Dufton F. P. Keenan A. E. Kingston

1988-01-01

321

New kinetic-spectrophotometric method for monitoring the concentration of iodine in river and city water samples.  

PubMed

A new kinetic method has been developed for the determination of iodine in water samples. The method is based on the catalytic effect of I(-) with the oxidation of Indigo Carmine (IC) by KBrO(3) in the sulfuric acid medium. The optimum conditions obtained are 0.16 M sulfuric acid, 1 × 10(-3) M of IC, 1 × 10(-2) M KBrO(3), reaction temperature of 35°C, and reaction time of 80 s at 612 nm. Under the optimized conditions, the method allowed the quantification of I(-) in a range of 12-375 ng/mL with a detection limit of 0.46 ng/mL. The method was applied to the determination of iodine in river and city water samples with the satisfactorily results. PMID:22392614

Farmany, A; Khosravi, A; Abbasi, S; Cheraghi, J; Hushmandfar, R; Sobhanardakani, S; Noorizadeh, H; Mortazavi, S S

2013-01-01

322

Determination of phenolic composition and antioxidant capacity of native red wines by high performance liquid chromatography and spectrophotometric methods  

Microsoft Academic Search

A reversed-phase high performance chromatographic method for simultaneous determination of 14 phenolic compounds in native red wines was developed in this study. The identified compounds contained gallic acid, (+)-catechin, 3,4-dihydroxybenzoic acid, chlorogenic acid, (?)-epicatechin, 4-hydroxybenzoic acid, syringic acid, caffeic acid, p-coumaric acid, rutin, resveratrol, myricetin, quercetin and kaempferol. The method includes liquid–liquid extraction of acidic pH with ethylacetate. The analysis

Esra Porgal?; Ebru Büyüktuncel

323

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

Microsoft Academic Search

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

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

2001-01-01

324

UV-vis absorption spectroscopy and multivariate analysis as a method to discriminate tequila  

NASA Astrophysics Data System (ADS)

Based on the UV-vis absorption spectra of commercially bottled tequilas, and with the aid of multivariate analysis, it is proved that different brands of white tequila can be identified from such spectra, and that 100% agave and mixed tequilas can be discriminated as well. Our study was done with 60 tequilas, 58 of them purchased at liquor stores in various Mexican cities, and two directly acquired from a distillery. All the tequilas were of the "white" type, that is, no aged spirits were considered. For the purposes of discrimination and quality control of tequilas, the spectroscopic method that we present here offers an attractive alternative to the traditional methods, like gas chromatography, which is expensive and time-consuming.

Barbosa-García, O.; Ramos-Ortíz, G.; Maldonado, J. L.; Pichardo-Molina, J. L.; Meneses-Nava, M. A.; Landgrave, J. E. A.; Cervantes-Martínez, J.

2007-01-01

325

UV-vis absorption spectroscopy and multivariate analysis as a method to discriminate tequila.  

PubMed

Based on the UV-vis absorption spectra of commercially bottled tequilas, and with the aid of multivariate analysis, it is proved that different brands of white tequila can be identified from such spectra, and that 100% agave and mixed tequilas can be discriminated as well. Our study was done with 60 tequilas, 58 of them purchased at liquor stores in various Mexican cities, and two directly acquired from a distillery. All the tequilas were of the "white" type, that is, no aged spirits were considered. For the purposes of discrimination and quality control of tequilas, the spectroscopic method that we present here offers an attractive alternative to the traditional methods, like gas chromatography, which is expensive and time-consuming. PMID:16829165

Barbosa-García, O; Ramos-Ortíz, G; Maldonado, J L; Pichardo-Molina, J L; Meneses-Nava, M A; Landgrave, J E A; Cervantes-Martínez, J

2007-01-01

326

A novel method for preparing epoxy-containing microcapsules via UV irradiation-induced interfacial copolymerization in emulsions  

Microsoft Academic Search

A novel method for producing epoxy resin-containing microcapsules via UV-initiated radical copolymerization in an epoxy emulsion was developed. Epoxydiacrylates and a polymerizable emulsifier were employed as the wall-formers, which tended to accumulate at the exterior layer of epoxy colloids during the emulsification process. Upon exposure to UV light, the shell phase consisting of the wall-formers was rapidly cured into solid

Ding Shu Xiao; Min Zhi Rong; Ming Qiu Zhang

2007-01-01

327

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

PubMed

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

Lee, Jinkee; Tripathi, Anubhav

2007-01-01

328

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

PubMed

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

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

2013-01-01

329

A method for optimizing the cosine response of solar UV diffusers  

NASA Astrophysics Data System (ADS)

Instruments measuring global solar ultraviolet (UV) irradiance at the surface of the Earth need to collect radiation from the entire hemisphere. Entrance optics with angular response as close as possible to the ideal cosine response are necessary to perform these measurements accurately. Typically, the cosine response is obtained using a transmitting diffuser. We have developed an efficient method based on a Monte Carlo algorithm to simulate radiation transport in the solar UV diffuser assembly. The algorithm takes into account propagation, absorption, and scattering of the radiation inside the diffuser material. The effects of the inner sidewalls of the diffuser housing, the shadow ring, and the protective weather dome are also accounted for. The software implementation of the algorithm is highly optimized: a simulation of 109 photons takes approximately 10 to 15 min to complete on a typical high-end PC. The results of the simulations agree well with the measured angular responses, indicating that the algorithm can be used to guide the diffuser design process. Cost savings can be obtained when simulations are carried out before diffuser fabrication as compared to a purely trial-and-error-based diffuser optimization. The algorithm was used to optimize two types of detectors, one with a planar diffuser and the other with a spherically shaped diffuser. The integrated cosine errors—which indicate the relative measurement error caused by the nonideal angular response under isotropic sky radiance—of these two detectors were calculated to be f2=1.4% and 0.66%, respectively.

Pulli, Tomi; Kärhä, Petri; Ikonen, Erkki

2013-07-01

330

Determination of eprosartan mesylate and hydrochlorothiazide in tablets by derivative spectrophotometric and high-performance liquid chromatographic methods.  

PubMed

Two new simple and selective assay methods have been presented for the analysis of eprosartan mesylate (EPR) and hydrochlorothiazide (HCT) in pharmaceutical formulations. The first method is based on first-derivative ultraviolet spectrophotometry with zero-crossing measurements at 246 and 279 nm for EPR and HCT, respectively. The assay was linear over the concentration ranges 3.0-14.0 µg/mL for EPR and 1.0-12.0 µg/mL for HCT. The quantification limits for EPR and HCT were found to be 1.148 and 0.581 µg/mL, respectively, while the detection limits were 0.344 µg/mL for EPR and 0.175 µg/mL for HCT. The second method involved isocratic reversed-phase liquid chromatography using a mobile phase composed of acetonitrile-10 mM phosphoric acid (pH 2.5) (40:60, v/v). Olmesartan was used as internal standard and the substances were detected at 272 nm. The linearity ranges were found to be 0.5-30 and 0.3-15.0 µg/mL for EPR and HCT, respectively. The limits of detection were found to be 0.121 µg/mL for EPR and 0.045 µg/mL for HCT. The limits of quantification were found to be 0.405 and 0.148 µg/mL for EPR and HCT, respectively. The proposed methods were successfully applied to the determination of commercially available tablets with a high percentage of recovery and good accuracy and precision. PMID:22576732

Hacio?lu, Fatma; Onal, Arma?an

2012-09-01

331

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

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 x 10(4) L mol(-1) cm(-1) and 2.5 x 10(5) L mol(-1) cm(-1) in aqueous and micellar media, respectively. The reaction is instantaneous and the maximum absorbance was obtained after 10 min at 490 nm and remains constant for over 24 h at room temperature. The linear calibration graphs were obtained for 0.1-30 mg L(-1) and 0.01-30 mg L(-1) of gold(III) in aqueous and surfactant media, respectively. The interference from over 50 cations, anions and complexing agents has been studied at 1 mg L(-1) of Au(III); most metal ions can be tolerated in considerable amounts in aqueous micellar solutions. The Sandell's sensitivity, the limit of detection and relative standard deviation (n = 9) were found to be 5 ng cm(-2), 1 ng mL(-1) and 2%, respectively in aqueous micellar solutions. Its sensitivity and selectivity are remarkably higher than that of other reagents in the literature. The proposed method was successfully used in the determination of gold in several standard reference materials (alloys and steels), environmental water samples (potable and polluted), and biological samples (blood and urine), geological, soil and complex synthetic mixtures. The results obtained agree well with those samples analyzed by atomic absorption spectrophotometry (AAS). PMID:19609392

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

2008-01-01

332

A Simple and Selective Spectrophotometric Method for the Determination of Trace Gold in Real, Environmental, Biological, Geological and Soil Samples Using Bis (Salicylaldehyde) Orthophenylenediamine  

PubMed Central

A simple high sensitive, selective, and rapid spectrophotometric method for the determination of trace gold based on the rapid reaction of gold(III) with bis(salicylaldehyde)orthophenylenediamine (BSOPD) in aqueous and micellar media has been developed. BSOPD reacts with gold(III) in slightly acidic solution to form a 1:1 brownish-yellow complex, which has an maximum absorption peak at 490 nm in both aqueous and micellar media. The most remarkable point of this method is that the molar absorptivities of the gold-BSOPD complex form in the presence of the nonionic TritonX-100 surfactant are almost a 10 times higher than the value observed in the aqueous solution, resulting in an increase in the sensitivity and selectivity of the method. The apparent molar absorptivities were found to be 2.3 × 104 L mol?1 cm?1 and 2.5 × 105 L mol?1 cm?1 in aqueous and micellar media, respectively. The reaction is instantaneous and the maximum absorbance was obtained after 10 min at 490 nm and remains constant for over 24 h at room temperature. The linear calibration graphs were obtained for 0.1–30 mg L?1 and 0.01–30 mg L?1 of gold(III) in aqueous and surfactant media, respectively. The interference from over 50 cations, anions and complexing agents has been studied at 1 mg L?1 of Au(III); most metal ions can be tolerated in considerable amounts in aqueous micellar solutions. The Sandell’s sensitivity, the limit of detection and relative standard deviation (n = 9) were found to be 5 ng cm?2, 1 ng mL?1 and 2%, respectively in aqueous micellar solutions. Its sensitivity and selectivity are remarkably higher than that of other reagents in the literature. The proposed method was successfully used in the determination of gold in several standard reference materials (alloys and steels), environmental water samples (potable and polluted), and biological samples (blood and urine), geological, soil and complex synthetic mixtures. The results obtained agree well with those samples analyzed by atomic absorption spectrophotometry (AAS).

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

2008-01-01

333

Simple Reversed-Phase HPLC Method with Spectrophotometric Detection for Measuring Acetaminophen-Protein Adducts in Rat Liver Samples  

PubMed Central

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.

Acharya, Miteshkumar; Lau-Cam, Cesar A.

2012-01-01

334

Quantitation of serrapeptase in formulations by UV method in the microplate format.  

PubMed

Serrapeptase is an anti-inflammatory, proteolytic enzyme isolated from the microorganism, Serratia sp. HY-6. Very few methods are available for the quantification of serrapeptase. The activity of the enzyme is determined by an ELISA assay, colorimetric method using casein as substrate or by HPLC method. These methods are lengthy, time consuming and require a number of reagents and solvents. Therefore an attempt was made to develop a simple alternative method for regular estimation of drug in formulations. Serrapeptase enzyme was estimated in formulations by using microplate readers which uses the principle of vertical photometry. Further this method was validated and the robustness of this method was checked by estimating the drug in various formulations including liposomes and marketed tablet formulations. A linear relationship between drug concentration and absorbance was observed between 1-4 microg/ml at 230 nm (R(2)=0.9911). The percentage recovery values of the drug in serrapeptase liposomes were found to lie within the standard limit (97-98%) which confirms the method is accurate and free from any positive or negative interference of the excipient. The low value of standard deviation obtained confirms the precision of the method. (+/-0.020 - +/-0.044). The drug content values in marketed tablets values obtained matched the label claim. The proposed microplate UV-method for determination of serrapeptase in formulations is novel, simple, inexpensive, fast, specific and robust. Thus this method could be a better alternative for regular estimation of drug in the various marketed formulations of serrapeptase. PMID:18855600

Sandhya, K V; Devi, S Gayathri; Mathew, Sam T

2008-10-01

335

Spectral absorbance of benthic cladoceran carapaces as a new method for inferring past UV exposure of aquatic biota  

NASA Astrophysics Data System (ADS)

We developed a method for measuring fossil cladoceran (Branchiopoda) carapace absorbance to infer past ultraviolet radiation (UV) exposure in lakes. This was done under the presumptions that cladocerans synthesize photoprotective compounds, of which melanin is the main UV-absorbing pigment, to their exoskeletons and melanin is preserved in sedimentary cladoceran remains. We extracted large-sized cladoceran (benthic Alona spp.) carapaces from subsections of sediment cores from two environmentally divergent lakes; a humic boreal forest lake in eastern Finland (past 1500 years) and a clear-water mountain lake in the Austrian Alps (past 300 years). We measured the absorbance of extracted carapaces with a spectrophotometer under visible light and UV wavelengths using an adapter, which was designed to hold the microfossils. When compared to the spectrum of synthetic melanin, the shapes of absorbance spectra at the 700-280 nm range suggested that the fossil carapaces contained melanin. The carapace absorbance under UV throughout the sediment cores was significantly higher in the clear-water alpine lake than in the humic boreal lake reflecting differences in the general underwater UV and optical environments between the sites. In addition, carapace absorbance was significantly higher during the Little Ice Age (LIA) than during pre- or post-LIA periods in both lakes. In the alpine lake, this was most likely a response to increased underwater UV induced by reduced primary production and more transparent water column during the cold summers of LIA, whereas reduced input of carbon compounds from the catchment through elongated permafrost and ice-cover periods likely induced higher water transparency in the boreal lake during this cold climate phase. We conclude that fossil melanin provides a good estimation of past underwater UV exposure in lakes with large cladoceran carapaces preserved in sediments and that the method introduced here is easy and cost- and time-efficient technique to be widely used in paleoaquatic UV inferences.

Nevalainen, Liisa; Rautio, Milla

2014-01-01

336

Review of UV spectroscopic, chromatographic, and electrophoretic methods for the cholinesterase reactivating antidote pralidoxime (2-PAM).  

PubMed

Pralidoxime (2-PAM) belongs to the class of monopyridinium oximes with reactivating potency on cholinesterases inhibited by phosphylating organophosphorus compounds (OPC), for example, pesticides and nerve agents. 2-PAM represents an established antidote for the therapy of anticholinesterase poisoning since the late 1950s. Quite high therapeutic concentrations in human plasma (about 13?µg/ml) lead to concentrations in urine being about 100 times higher allowing the use of less sensitive analytical techniques that were used especially in the early years after 2-PAM was introduced. In this time (mid-1950s until the end of the 1970s) 2-PAM was most often analyzed by either paper chromatography or simple UV spectroscopic techniques omitting any sample separation step. These methods were displaced completely after the establishment of column liquid chromatography in the early 1980s. Since then, diverse techniques including cation exchange, size-exclusion, reversed-phase, and ligand-exchange chromatography have been introduced. Today, the most popular method for 2-PAM quantification is ion pair chromatography often combined with UV detection representing more than 50% of all column chromatographic procedures published. Furthermore, electrophoretic approaches by paper and capillary zone electrophoresis have been successfully used but are seldom applied. This review provides a commentary and exhaustive summary of analytical techniques applied to detect 2-PAM in pharmaceutical formulations and biological samples to characterize stability and pharmacokinetics as well as decomposition and biotransformation products. Separation techniques as well as diverse detectors are discussed in appropriate detail allowing comparison of individual preferences and limitations. In addition, novel data on mass spectrometric fragmentation of 2-PAM are provided. PMID:21953823

John, Harald; Blum, Marc-Michael

2012-01-01

337

Spectrophotometric titration of zirconium in siliceous materials.  

PubMed

An accurate and selective complexometric titration procedure based upon a spectrophotometrically detected end-point has been developed for the determination of zirconium in glasses, glass-ceramics and refractories. A p-bromomandelic acid separation step for zirconium imparts excellent selectivity to the procedure. The method is particularly important for the 1-5% concentration range where a simple, accurate and selective method for the determination of zirconium has been lacking. PMID:18962344

Sugawara, K F; Su, Y S; Strzegowski, W R

338

A vacuum ultraviolet spectrophotometric system  

NASA Technical Reports Server (NTRS)

The development of a vacuum ultraviolet spectrophotometric system for measuring transmittance and reflectance at variable angles is presented. Using various detectors and sources, the spectrophotometric system has been used for wavelengths from 80 nm to 300 nm with optical components up to 80 mm in diameter. The capability exists to make measurements through the visible range.

Spann, James F.; Keffer, Charles E.; Zukic, Muamer

1993-01-01

339

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

PubMed Central

Sulfasalazine (SSZ) was subjected to degradation under the conditions of hydrolysis (acid, alkali, and water), oxidation (30% H2O2), dry heat, and photolysis (UV-VIS light) in accordance with the ICH guidelines. An RP-HPLC method was developed to study the degradation behavior. No degradation was noted under any condition except alkaline hydrolysis where SSZ was degraded to a single minor product. SSZ was optimally resolved from this product on an XTerra® RP18 column with a mobile phase composed of methanol and an ammonium acetate buffer (10 mM, pH 7.0) (48:52, v/v) delivered at a rate of 0.8 mL/min in an isocratic mode. The method was validated and found to be linear (r2=0.99945), precise (%RSD <2), robust, and accurate (94–102%) in the concentration range of 0.5–50 ?g/mL of SSZ. The PDA analysis of the degraded sample revealed the SSZ peak purity to be 998.99 and the drug peak eluted with a resolution factor of >2 from the nearest resolving peak, indicating the method to be selectively stability-indicating for the drug analysis. The method was applied successfully for the stability testing of the commercially available SSZ tablets that were under varied ICH-prescribed conditions. An explanation for the unusual stability of the drug when exposed to acidic hydrolysis, despite the presence of the sulfonamide linkage, is also discussed.

Saini, Balraj; Bansal, Gulshan

2014-01-01

340

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

341

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

342

On-line spectrophotometric method for monitoring weak residual absorption of CaMoO{sub 4} single crystals near the intrinsic luminescence peak  

SciTech Connect

The optical and spectral characteristics of isotopically enriched Czochralski-grown {sup 40}Ca{sup 100}MoO{sub 4} single crystals have been investigated. This material is promising for detecting double neutrinoless {beta} decay. The possibility and the technique of spectrophotometric monitoring of weak residual absorption near the intrinsic luminescence peak of this scintillation material, which is designed for developing new-generation detectors of elementary particles, are considered.

Buzanov, O. A., E-mail: fedorov-metrology@yandex.ru [OAO Fomos-Materials (Russian Federation); Kanevskii, V. M. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)] [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Kornoukhov, V. N. [OAO Fomos-Materials (Russian Federation)] [OAO Fomos-Materials (Russian Federation); Nabatov, B. V.; Nabatov, V. V.; Fedorov, V. A. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)] [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

2013-11-15

343

On-line spectrophotometric method for monitoring weak residual absorption of CaMoO4 single crystals near the intrinsic luminescence peak  

NASA Astrophysics Data System (ADS)

The optical and spectral characteristics of isotopically enriched Czochralski-grown 40Ca100MoO4 single crystals have been investigated. This material is promising for detecting double neutrinoless ? decay. The possibility and the technique of spectrophotometric monitoring of weak residual absorption near the intrinsic luminescence peak of this scintillation material, which is designed for developing new-generation detectors of elementary particles, are considered.

Buzanov, O. A.; Kanevskii, V. M.; Kornoukhov, V. N.; Nabatov, B. V.; Nabatov, V. V.; Fedorov, V. A.

2013-11-01

344

High throughput UV method for the estimation of thermodynamic solubility and the determination of the solubility in biorelevant media  

Microsoft Academic Search

The growing interest for high quality solubility data in the early stages of drug discovery suggested a detailed optimization of experimental conditions for a 96-well HTS UV method in order to obtain solubility values close to thermodynamic solubility measured by shake-flask method. Results have shown that solubility data obtained by the HTS approach were highly dependent on shaking intensity and

Bruno Bard; Sophie Martel; Pierre-Alain Carrupt

2008-01-01

345

A simple sample preparation with HPLC–UV method for estimation of tiropramide from plasma: Application to bioequivalence study  

Microsoft Academic Search

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 C18 column using mixture of water and acetonitrile as mobile phase with UV detection set at 230nm. The retention time of internal

Khan Imran; Loya Punnamchand; Saraf Madhusudan Natvarlal

2007-01-01

346

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

347

A simple and rapid spectrophotometric method for determination of ultra trace amounts of thallium(III) with 4-(4'-N,N-dimethylaminophenyl) urazole as a new reagent.  

PubMed

A simple and selective spectrophotometric method is proposed for the determination of ultra trace amounts of Tl(III). The reported method is based on the oxidation of 4-(4'-N,N-dimethylaminophenyl)urazole (DAPU) to the corresponding triazolinedione (TAD) by Tl(III) at pH 4.0. The reaction was monitored spectrophotometrically by measuring the increasing color of TAD compound at 514 nm by the fixed-time method. At a given time of 2.0 min at 30 degrees C, the working range of calibration was 5.0 x 10(-8) - 2.0 x 10(-5) M Tl(III) and detection limit of 5.0 x 10(-8) M was obtained. The influences of pH, reagent concentration, ionic strength and temperature were studied. The effect of diverse ions on the determination of Tl(III) by the proposed method was also investigated. Thallium in real samples was determined by this method, with satisfactory results. PMID:16398353

Rezaei, Behzad; Mallakpour, Shadpour; Khalili, Honieh; Rafiee, Zahra

2005-01-01

348

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

PubMed

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

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

2007-07-01

349

New Methods for UV Treatment of Milk For Improved Food Safety And Product Quality  

Microsoft Academic Search

A novel Ultraviolet (UV) system was shown to be capable of reliably achieving in excess of a 3 log10 reduction in bacteria measured as standard plate, psychrotrophic, coliform and thermoduric counts. Sensory analysis indicated that excessive or improper treatment may affect milk flavor so that care must be taken in the way that UV treatment is applied. Possible applications include

D. J. Reinemann; P. Gouws; T. Cilliers; K. Houck; J. R. Bishop

350

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

Microsoft Academic Search

Thin-layer chromatographic (TLC)-UV densitometric and gas-chromatographic-mass spectrometric detection (GC-MSD) methods were developed for simultaneous quantification of morphine and codeine in poppy capsules (Papaver somniferum). Morphine and codeine were isolated by extraction with chloroform: isopropanol (3:1, v\\/v) at pH=8.5 and by solid-phase extraction on Snap-Cap cartridges at pH=8.5. The TLC-UV densitometric quantification was performed by external standard method on silica gel

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

1998-01-01

351

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

PubMed

Thin-layer chromatographic (TLC)-UV densitometric and gas-chromatographic-mass spectrometric detection (GC-MSD) methods were developed for simultaneous quantification of morphine and codeine in poppy capsules (Papaver somniferum). Morphine and codeine were isolated by extraction with chloroform: isopropanol (3:1, v/v) at pH = 8.5 and by solid-phase extraction on Snap-Cap cartridges at pH = 8.5. The TLC-UV densitometric quantification was performed by external standard method on silica gel plates using ethyl acetate: toluene: methanol: ammonia (68:17:10:5, v/v) as developing solvent and UV detection at 275 nm. For the GC-MSD analysis, the drugs were derivatized with acetic anhydride: pyridine (1:1, v/v) and separated on a 30 m HP5 capillary column. The quantification was performed using nalorphine as internal standard. PMID:9919965

Popa, D S; Oprean, R; Curea, E; Preda, N

1998-12-01

352

Spectrophotometric Determination of Protein in Milk1  

Microsoft Academic Search

SUMMARY The spectrophotometric method of Haugaard and Danun (1) for estimating the protein content of skimmilk at wavelength 277 mt~ was modified for raw and pasteurized milk, sterile concentrate, and cream as follows: Add 0.5 ml of butylamine to 0.5 ml of milk, heat to 65 C for 5 rain, add 25 ml of a mixture of 0.3% each of

S. Nakai; H. K. Wilson; E. O. Herreid

1964-01-01

353

Quality assurance of solar spectral UV-measurements: methods and use of the SHICrivm software tool  

NASA Astrophysics Data System (ADS)

Ground-based UV-irradiance measurements are crucial for determining the long-term changes and trends in biologically and/or photo-chemically relevant solar UV-radiation reaching the Earth's surface. Such changes in UV-radiation levels have probably occurred and/or are expected due to ozone depletion and climate change. In order to analyse UV-irradiation levels in relation to atmospheric parameters and to facilitate an assessment of the European UV-climate a European database (EUVDatabase) has been set up within the EDUCE-project (EC-contract EVK2-CT-1999-00028). High quality UV-data-sets from across the continent are assessable from the EUVDatabase (http://uv.fmi.fi/uvdb/). An accurate analysis of the UV-climate and long term changes therein requires quality assurance of the spectral data. The SHICrivm software tool (http://www.rivm.nl/shicrivm) is developed to analyse several quality aspects of measured UV-spectra. The SHICrivm tool is applied to over one million spectra from the EUVDatabase and detects for each measured spectrum: the accuracy of the wavelength calibration from 290 up to 500 nm, the lowest detectable irradiance level, the occurrence of non-natural spikes in spectra, deviations in spectral shape, and identifies possible irradiance scale errors in the UV-range. In addition the SHIC-package can be used to correct wavelength scale errors and non-natural spectral spikes. A deconvolution and convolution algorithm is included to improve the comparibility of spectra obtained with different instruments, and to allow a fully comparable analysis of biologically weighted UV-dose for instruments with various spectral characteristics. Within the context of the EDUCE-project data from over 20 UV-monitoring stations are retrieved from the database and a quality assessment is performed using the SHIC-tool. The quality parameters are presented by means of a simple scheme of coloured quality flags. Spectra that meet the WMO-criteria for spectral measurements are reported as GREEN. The majority of spectral data meet these high quality criteria, however sub sets of the data are identified which do not meet the lowest quality criteria. The overall quality is discussed from the perspective of a potential user and the implications regarding the determination of the rate of change of the annual UV ground flux.

Williams, J. E.; den Outer, P. N.; Slaper, H.

2003-04-01

354

A validated spectrophotometric and liquid chromatography method for determination and purity evaluation of 4-methoxy-2-[2-hydroxy-3(4-phenyl-1-piperazinyl)]propyl-2,3-dihydro-6-methyl-1,3-dioxo-1H-pyrrolo[3,4-c]pyridine.  

PubMed

A spectrophotometric analysis of the UV-spectrum of 4-methoxy-2-[2-hydroxy-3(4-phenyl-1-piperazinyl)]propyl-2,3-dihydro-6-methyl-1,3-dioxo-1H-pyrrolo[3,4-c]pyridine (I) in 0.01 M HCl was performed by determining the values of specific absorption coefficients at the following analytical wavelengths: 224, 285 and 348 nm. The separation by means of TLC of compound I and of its five decomposition products was also studied. Silica gel coated plates (60 F(254)) were used and the mobile phase was consisted of butanol-acetic acid (1.05 kg/l)-water (80:12:30, v/v/v). The HPLC method (LiChrosorb(R) 100 RP-18 column 250 x 4.0 mm I.D., dp=5 microm; mobile phase: acetonitrile-0.01 M phosphate buffer (H(3)PO(4)+KH(2)PO(4); pH 3) (50:50, v/v-phase A) or (30:70, v/v-phase B) was validated by determination of the following parameters: selectivity, precision, linearity, stability of the analite and LOD as well as LOQ. Kinetic studies of the decomposition process of I in both acidic and alkaline environments indicate instability of the imide group. PMID:12818690

Muszalska, Izabela; Sadowska, Helena; Szkatula, Dominika

2003-07-01

355

Determination of total chromium in tannery waste water by inductively coupled plasma-atomic emission spectrometry, flame atomic absorption spectrometry and UV–visible spectrophotometric methods  

Microsoft Academic Search

The determination of total chromium in different streams of tannery effluents were carried out by the digestion of samples in a HNO3\\/H2SO4 mixture followed by KMnO4 oxidation, which resulted in the complete conversion of Cr(III) to Cr(VI). The Cr(VI) (Cr2O72?) species present in these samples were estimated by inductively coupled plasma-atomic emission spectrometry (ICP-AES), flame atomic absorption spectrometry (FAAS) and

S. Balasubramanian; V. Pugalenthi

1999-01-01

356

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

357

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

358

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

359

Screening method for identification of adulterate and fake tequilas by using UV–VIS spectroscopy and chemometrics  

Microsoft Academic Search

Based on UV–VIS spectroscopy and chemometric techniques, a screening method is presented with which the studied brands of white and rested tequila can be differentiated among them and on the other hand, adulterate and fake tequilas can be distinguished from the corresponding genuine brands. Eighty bottles of tequila (39 white type and 41 rested type) were studied and purchased at

Ulises Contreras; O. Barbosa-García; J. L. Pichardo-Molina; G. Ramos-Ortíz; J. L. Maldonado; M. A. Meneses-Nava; N. E. Ornelas-Soto; P. L. López-de-Alba

2010-01-01

360

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 25°C 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 99.0–100.0 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.

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

2011-01-01

361

Indirect spectrophotometric determination of reducing sugars and ascorbic acid using phenolphthalin as reagent  

Microsoft Academic Search

Summary An indirect spectrophotometric method has been developed for the determination of reducing sugars and ascorbic acid. A known excess of ferricyanide is allowed to react with the reductant, and the surplus ferricyanide is determined spectrophotometrically with phenolphthalin. The method is simple and reproducible, with an error of less than 2%.

Salah Shahine; Rafaa Mahmoud

1980-01-01

362

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

PubMed Central

An ultra-fast liquid chromatographic method and two UV spectroscopic methods were developed for the determination of cephalexin monohydrate in pharmaceutical dosage forms. Isocratic separation was performed on an Enable C18G column (250 mm × 4.6 mm i.d., 5 ?m) using methanol:0.01 M TBAHS (50:50, v/v) as the mobile phase at a flow rate of 1.0 ml/min. The PDA detection wavelength was set at 254 nm. The UV spectroscopic method was performed at 261 nm and at 256–266 nm for the AUC method using a phosphate buffer (pH=5.5). The linearity was observed over a concentration range of 1.0–120 ?g/ml for UFLC and both of the UV spectroscopic methods (correlation coefficient=0.999). The developed methods were validated according to ICH guidelines. The relative standard deviation values for the intraday and interday precision studies were < 2%, and the accuracy was > 99% for all of the three methods. The developed methods were used successfully for the determination of cephalexin in dry syrup formulation.

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

2013-01-01

363

Coumarins in horse chestnut flowers: isolation and quantification by UPLC method.  

PubMed

The coumarins: scopoletin, esculetin and fraxetin were isolated from the flowers of horse chestnut (Aesculus hippocastanum L., Hippocastanaceae) and identified by spectrophotometric methods (UV, 1H, 13C NMR, ESI-MS). Their content, determined using the Ultra Performance Liquid Chromatography (UPLC), was 0.41, 0.13 and 0.05%, respectively. PMID:23757942

Dudek-Makuch, Marlena; Mat?awska, Irena

2013-01-01

364

The winds of O-stars. I - An analysis of the UV line profiles with the SEI method  

NASA Technical Reports Server (NTRS)

The theoretical UV P Cygni profiles of the UV resonance lines for C IV, N V, Si IV, C III, and N IV of 26 O-type stars and one B star were calculated using the SEI method described by Lamers et al. (1987), taking into account the effects of turbulence in the wind, limb darkening, photospheric lines, and interstellar Ly alpha. The results were compared with profiles observed with the IUE satellite. The profile fits were found to be very accurate, showing significant improvement over previously obtained fits with the Sobolev (1958) method. The SEI method and the line fitting analysis are described and the results are presented in terms of the column densities and distributions of absorbing atoms, and the velocity laws.

Groenewegen, M. A. T.; Lamers, H. J. G. L. M.

1989-01-01

365

The winds of O-stars. I - an analysis of the UV line profiles with the SEI method  

NASA Astrophysics Data System (ADS)

The theoretical UV P Cygni profiles of the UV resonance lines for C IV, N V, Si IV, C III, and N IV of 26 O-type stars and one B star were calculated using the SEI method described by Lamers et al. (1987), taking into account the effects of turbulence in the wind, limb darkening, photospheric lines, and interstellar Ly alpha. The results were compared with profiles observed with the IUE satellite. The profile fits were found to be very accurate, showing significant improvement over previously obtained fits with the Sobolev (1958) method. The SEI method and the line fitting analysis are described and the results are presented in terms of the column densities and distributions of absorbing atoms, and the velocity laws.

Groenewegen, M. A. T.; Lamers, H. J. G. L. M.

1989-09-01

366

Two Methods for Retrieving UV Index for All Cloud Conditions from Sky Imager Products or Total SW Radiation Measurements.  

PubMed

Cloud effects on UV Index (UVI) and total solar radiation (TR) as a function of cloud cover and sunny conditions (from sky images) as well as of solar zenith angle (SZA) are assessed. These analyses are undertaken for a southern-hemisphere mid-latitude site where a 10-years dataset is available. It is confirmed that clouds reduce TR more than UV, in particular for obscured Sun conditions, low cloud fraction (<60%) and large SZA (>60°). Similarly, local short-time enhancement effects are stronger for TR than for UV, mainly for visible Sun conditions, large cloud fraction and large SZA. Two methods to estimate UVI are developed: (1) from sky imaging cloud cover and sunny conditions, and (2) from TR measurements. Both methods may be used in practical applications, although Method 2 shows overall the best performance, as TR allows considering cloud optical properties. The mean absolute (relative) differences of Method 2 estimations with respect to measured values are 0.17 UVI units (6.7%, for 1 min data) and 0.79 Standard Erythemal Dose (SED) units (3.9%, for daily integrations). Method 1 shows less accurate results but it is still suitable to estimate UVI: mean absolute differences are 0.37 UVI units (15%) and 1.6 SED (8.0%). PMID:24645969

Badosa, Jordi; Calbó, Josep; Mckenzie, Richard; Liley, Ben; González, Josep-Abel; Forgan, Bruce; Long, Charles N

2014-07-01

367

Spectrophotometric Estimation of Olmesartan Medoxomil and Hydrochlorothiazide in Tablet  

PubMed Central

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

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

2010-01-01

368

UV–vis absorption spectroscopy and multivariate analysis as a method to discriminate tequila  

Microsoft Academic Search

Based on the UV–vis absorption spectra of commercially bottled tequilas, and with the aid of multivariate analysis, it is proved that different brands of white tequila can be identified from such spectra, and that 100% agave and mixed tequilas can be discriminated as well. Our study was done with 60 tequilas, 58 of them purchased at liquor stores in various

O. Barbosagarcia; G. Ramosortiz; J. L. Maldonado; J. L. Pichardo-Molina; M. A. Meneses-Nava; J. E. A. Landgrave; J. Cervantesmartinez

2007-01-01

369

A HPLC method to evaluate the influence of photostabilizers on cosmetic formulations containing UV-filters and vitamins A and E  

Microsoft Academic Search

This paper reports a simple and reliable HPLC method to evaluate the influence of two currently available photostabilizers on cosmetic formulations containing combined UV-filters and vitamins A and E. Vitamins and UV-filters, widely encountered in products of daily use have to be routinely evaluated since photoinstability can lead to reductions in their efficacy and safety. UV-irradiated formulation samples were submitted

Lorena Rigo Gaspar; Patricia Maria Berardo Gonçalves Maia Campos

2010-01-01

370

A partition experimental evidence of molecular complex formation of some quinones with sodium dodecyl sulphate anion in aqueous phase by spectrophotometric method  

NASA Astrophysics Data System (ADS)

In an experiment involving partition of four different quinones between their saturated solutions in CCl 4 and aqueous solution of sodium dodecyl sulphate (SDS), done spectrophotometrically, it was observed that below the critical micellisation concentration (c.m.c.) of SDS, the solubility of each quinone in aqueous phase increased linearly with [SDS], just above c.m.c. it dropped sharply and then again increased, becoming nearly constant at very high [SDS]. The absorption ?max of each quinone (excepting o-chloranil) in aqueous SDS showed a red shift relative to that in CCl 4 and the red-shifted ?max is independent of [SDS]. These observations were rationalised by considering complexation and phase equilibria.

Ray, Asim K.; Saha, Avijit; Mukherjee, Asok K.

2005-01-01

371

[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 ISO 15189 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 ISO 15189 and the accreditation technical guide in Human Health SH-GTA-04. PMID:24113450

Harlé, Alexandre; Lion, Maëva; Husson, Marie; Dubois, Cindy; Merlin, Jean-Louis

2013-01-01

372

Spectrophotometric estimation of cobalt with ninhydrin  

PubMed Central

A violet coloured complex was developed when cobalt metal reacts with ninhydrin at pH 8.2, using sodium acetate buffer solution. Absorbance of the complex was measured at 395 nm. Various factors, such as volume of the ligand used, solution pH, stability of the complex with time and interference of other metals, which effect the complex formation have been studied in detail. Present developed method can be used for the spectrophotometric estimation of cobalt with ninhydrin complex. The method is simple, selective and cheap for the determination of cobalt in very less time.

Mahmood, Karamat; Wattoo, Feroza Hamid; Wattoo, Muhammad Hamid Sarwar; Imran, Muhammad; Asad, Muhammad Javaid; Tirmizi, Syed Ahmed; Wadood, Abdul

2012-01-01

373

FTIR and UV\\/vis as methods for evaluation of oxidative degradation of model paper: DFT approach for carbonyl vibrations  

Microsoft Academic Search

The oxidative route of cellulose degradation during artificial ageing of paper in humid air (RH 59%, 90°C) has been followed by FTIR and UV\\/vis spectroscopic methods providing a vibrational pattern of carbonyl groups and electronic transitions of chromophores, respectively. Conjugated ketonic groups with vibrational modes around 1610cm?1 were correlated to the chromophores emerging in the range between 230 and 440nm

T. ?ojewski; P. Mi?kowiec; M. Missori; A. Luba?ska; L. M. Proniewicz; J. ?ojewska

2010-01-01

374

Comparison of LC detection methods in the investigation of non-UV detectable organic impurities in a drug substance  

Microsoft Academic Search

HPLC Analysis with different detection methods was shown to be essential in the separation and identification of unknown organic impurities in a drug substance. The impurities were found to exhibit very weak or no response to standard ultraviolet (UV) absorption detection. LC-MS, LC-NMR, indirect, refractive index and evaporative light-scattering detection were used to quantify and identify the impurities in this

S. D. McCrossen; D. K. Bryant; B. R. Cook; J. J. Richards

1998-01-01

375

Comparison of Visual and Spectrophotometric Methods of Broth Microdilution MIC End Point Determination and Evaluation of a Sterol Quantitation Method for In Vitro Susceptibility Testing of Fluconazole and Itraconazole against Trailing and Nontrailing Candida Isolates  

PubMed Central

Visual determination of MIC end points for azole antifungal agents can be complicated by the trailing growth phenomenon. To determine the incidence of trailing growth, we performed testing of in vitro susceptibility to fluconazole and itraconazole using the National Committee for Clinical Laboratory Standards broth microdilution M27-A reference procedure and 944 bloodstream isolates of seven Candida spp., obtained through active population-based surveillance between 1998 and 2000. Of 429 C. albicans isolates, 78 (18.2%) showed trailing growth at 48 h in tests with fluconazole, and 70 (16.3%) showed trailing in tests with itraconazole. Of 118 C. tropicalis isolates, 70 (59.3%) showed trailing growth in tests with fluconazole, and 35 (29.7%) showed trailing in tests with itraconazole. Trailing growth was not observed with any of the other five Candida spp. tested (C. dubliniensis, C. glabrata, C. krusei, C. lusitaniae, and C. parapsilosis). To confirm whether or not isolates that showed trailing growth in fluconazole and/or itraconazole were resistant in vitro to these agents, all isolates that showed trailing growth were retested by the sterol quantitation method, which measures cellular ergosterol content rather than growth inhibition after exposure to azoles. By this method, none of the trailing isolates was resistant in vitro to fluconazole or itraconazole. For both agents, a 24-h visual end point or a spectrophotometric end point of 50% reduction in growth relative to the growth control after 24 or 48 h of incubation correlated most closely with the result of sterol quantitation. Our results indicate that MIC results determined by either of these end point rules may be more predictive of in vivo outcome for isolates that give unclear visual end points at 48 h due to trailing growth.

Arthington-Skaggs, Beth A.; Lee-Yang, Wendy; Ciblak, Meral A.; Frade, Joao P.; Brandt, Mary E.; Hajjeh, Rana A.; Harrison, Lee H.; Sofair, Andre N.; Warnock, and David W.

2002-01-01

376

Study of Degradation Profile and Development of Stability Indicating Methods for Cefixime Trihydrate  

PubMed Central

The degradation behavior of cefixime trihydrate was investigated under different stress conditions of acidic hydrolysis, alkaline hydrolysis and oxidation using spectrophotometry. Stability indicating spectrophotometric methods were developed that could separate the drug from its degradation products formed under these stress conditions. The UV spectral characteristics of the drug and degraded products were quite different and zero and first order derivative ultraviolet spectrophotometric methods were used to study the extent of degradation. Cefixime trihydrate was found to degrade extensively under experimental conditions. The methods were validated by establishing the linearity, inter and intraday precision, accuracy, selectivity and specificity.

Gandhi, S. P.; Rajput, S. J.

2009-01-01

377

Study of degradation profile and development of stability indicating methods for cefixime trihydrate.  

PubMed

The degradation behavior of cefixime trihydrate was investigated under different stress conditions of acidic hydrolysis, alkaline hydrolysis and oxidation using spectrophotometry. Stability indicating spectrophotometric methods were developed that could separate the drug from its degradation products formed under these stress conditions. The UV spectral characteristics of the drug and degraded products were quite different and zero and first order derivative ultraviolet spectrophotometric methods were used to study the extent of degradation. Cefixime trihydrate was found to degrade extensively under experimental conditions. The methods were validated by establishing the linearity, inter and intraday precision, accuracy, selectivity and specificity. PMID:20502552

Gandhi, S P; Rajput, S J

2009-07-01

378

Highly sensitive catalytic spectrophotometric determination of ruthenium  

NASA Astrophysics Data System (ADS)

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 526 nm. 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 (? At) versus added Ru(III) amounts in the range of 0.101-2.526 ng ml -1 is plotted. Under the optimum conditions, the sensitivity of the proposed method, i.e. the limit of detection corresponding to 5 min is 0.08 ng ml -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.

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

2008-01-01

379

APPARATUS AND METHOD FOR TREATING POLLUTANTS IN A GAS USING HYDROGEN PEROXIDE AND UV LIGHT  

NASA Technical Reports Server (NTRS)

An apparatus for treating pollutants in a gas may include a source of hydrogen peroxide, and a treatment injector for creating and injecting dissociated hydrogen peroxide into the flow of gas. The treatment injector may further include an injector housing having an inlet, an outlet, and a hollow interior extending there between. The inlet may be connected in fluid communication with the source of hydrogen peroxide so that hydrogen peroxide flows through the hollow interior and toward the outlet. At least one ultraviolet (UV) lamp may be positioned within the hollow interior of the injector housing. The at least one UV lamp may dissociate the hydrogen peroxide flowing through the tube. The dissociated hydrogen peroxide may be injected into the flow of gas from the outlet for treating pollutants, such as nitrogen oxides.

Cooper, Charles David (Inventor); Clauseu, christian Anthony (Inventor)

2005-01-01

380

Apparatus and method for treating pollutants in a gas using hydrogen peroxide and UV light  

NASA Technical Reports Server (NTRS)

An apparatus for treating pollutants in a gas may include a source of hydrogen peroxide, and a treatment injector for creating and injecting dissociated hydrogen peroxide into the flow of gas. The treatment injector may further include an injector housing having an inlet, an outlet, and a hollow interior extending therebetween. The inlet may be connected in fluid communication with the source of hydrogen peroxide so that hydrogen peroxide flows through the hollow interior and toward the outlet. At least one ultraviolet (UV) lamp may be positioned within the hollow interior of the injector housing. The at least one UV lamp may dissociate the hydrogen peroxide flowing through the tube. The dissociated hydrogen peroxide may be injected into the flow of gas from the outlet for treating pollutants, such as nitrogen oxides.

Cooper, Charles David (Inventor); Clausen, Christian Anthony (Inventor)

2005-01-01

381

Spectrophotometric Determination of Adefovir Dipivoxil in bulk and Pharmaceutical Formulation  

Microsoft Academic Search

Two selective and sensitive spectrophotometric methods have been developed for the estimation of adefovir dipivoxil in bulk and pharmaceutical preparations. Adefovir dipivoxil was subjected to acid hydrolysis and the hydrolysed product used for the estimation. The methods are based on the reaction with 3-methyl-2-benzothiazolinone hydrazone in the presence of ferric chloride, to form a colored species with absorption maxima at

ZAHEER AHMED; Y. N. MANOHARA; K. P. CHANNABASAWARAJ; MANISH MAJUMDAR

382

Combined cloud point-solid phase extraction by dispersion of TiO2 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 0.5-90.0µgL(-1) of Zn(2+) (r=0.9996). An enrichment factor of 80 was achieved and the limit of detection for Zn(2+) was 0.33µgL(-1). The relative standard deviation (RSD) for eight replicate measurements of 10µgL(-1) and 60µgL(-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

383

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

PubMed Central

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

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

2010-01-01

384

Sensitive determination of phenylarsenic compounds based on a dual preconcentration method with capillary electrophoresis/UV detection.  

PubMed

A novel method based on off-line hollow fiber based liquid liquid liquid microextraction (HF-LLLME) combined with on-column anion selective exhaustive injection (ASEI)-capillary electrophoresis/ultraviolet (CE/UV) detection was proposed for the speciation of five phenylarsenic compounds including phenylarsonic acid (PAA), 4-aminophenylarsonic acid (4-APAA), 4-hydroxyphenylarsonic acid (4-HPAA), 4-nitrophenylarsonic acid (4-NPAA) and 3-nitro-4-hydroxyphenylarsonic acid (NHPAA) in this paper. In HF-LLLME, the target analytes were extracted from 5 mL aqueous samples (donor solution pH 2.15) through a thin phase of tributyl phosphate (TBP) inside the pores of a polypropylene hollow fiber and finally into an 18 ?L 0.8 mmol/L Tris acceptor solution inside the lumen of the hollow fiber. Following HF-LLLME, the acceptor solutions were directly analyzed by ASEI-CE/UV. For ASEI, a large plug of water (91% length of total capillary) was introduced into the separation capillary before sample injection in order to prolong the sample injection time, and thus enhance the stacking efficiency. Under the optimized ASEI conditions, up to 236-fold of enrichment factor (EF) was obtained for the ASEI-CE/UV determination of target phenylarsenic compounds. By combining HF-LLLME with ASEI-CE/UV, EFs ranging from 155 to 1780-fold were achieved and the limits of detection (LODs) (at a signal-to-noise ratio of 3) were in the range of 0.68-6.90 ?g/L for five phenylarsenic compounds; the relative standard deviations (RSDs) of corrected peak area were 5.6-11.8%. The proposed HF-LLLME-ASEI-CE/UV method was applied for the determination of five target phenylarsenic compounds in pig feed from a local pig farm, and storage pig litter, soil in agricultural field and lake water collected near this pig farm, the recoveries for the spiked samples were in the range of 85.7-104.5%, 66.7-96.2%, 28.9-46.9% and 86.9-107.8% for pig feed, pig litter, soil and lake water, respectively. PMID:21683369

Li, Pingjing; Hu, Bin

2011-07-22

385

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

386

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

387

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

PubMed

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

Shyla, B; Nagendrappa, G

2013-06-01

388

Spectrophotometric estimation of azithromycin in tablets.  

PubMed

The present manuscript describes a simple, sensitive, accurate, precise and economical visible spectrophotometric method for the estimation of azithromycin from tablet formulation. The method is based on the reduction of potassium permanganate in alkaline medium with azithromycin. The measurement of decrease in absorbance of potassium permanganate at 547 nm was done, as it decolourises upon reduction by azithromycin. The method was used to determine between 2 and 20 ?g/ml of azithromycin in the final measured solution. There is no interference from the ingredients commonly found in azithromycin tablets with this method. The results for the determination of azithromycin in tablets were in good agreement with the labelled quantities and related analytical parameters are calculated. PMID:23626394

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

2012-07-01

389

Spectrophotometric Estimation of Azithromycin in Tablets  

PubMed Central

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

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

2012-01-01

390

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

PubMed Central

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

Singh, Jaswant; Singh, Rudra P.

2014-01-01

391

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

392

Spectrophotometric and high performance liquid chromatographic determination of cetirizine dihydrochloride in pharmaceutical tablets.  

PubMed

Derivative spectrophotometric, colorimetric and high performance liquid chromatographic methods, for the determination of the antihistaminic cetirizine dihydrochloride in tablet form were described. Spectrophotometrically, cetirizine was determined by the measurement of its first (1D) and second (2D) derivative amplitudes at 239 (peak) and 243-233 nm (peak-to-trough), respectively. The aqueous solutions obeyed Beer's law in the concentration ranges of 1.2-10.0 and 0.8-10.0 micrograms ml-1 for 1D and 2D measurements, respectively. The colorimetric procedure was based on measuring the absorbency of the coloured chromogen resulted from the reaction between cetirizine sodium salt in polar solvent (DMF) and chloranil at 556 nm. The relation with concentrations was linear over 120-250 micrograms ml-1. Optimization of the reaction conditions was studied. At the same time, investigation of the complex formed was made with respect to its composition and the associated constant. A simple liquid chromatographic assay has been developed for the determination of cetirizine dihydrochloride in the presence of one of its synthesis precursor (hydroxyzine hydrochloride). A Bondapak-C18 column was used with a mobile phase consisting of acetonitrile/0.01 M ammonium dihydrogen phosphate (32:68, v/v) containing 0.1% w/v tetrabutyl ammonium hydrogen sulphate adjusted to pH 3 with phosphoric acid at a flow rate of 2 ml min-1. With salicylic acid as internal standard, quantitation was achieved with UV detection at 230 nm based on the peak height ratios. Beer's law was obeyed in a concentration range of 3-35 micrograms ml-1 and the regression line equation was derived with a correlation coefficient of 0.9999. The validity of the methods was further confirmed using the standard addition method. The proposed procedures were successfully applied to the determination of cetirizine in bulk and tablet form, with high percentage of recovery, good accuracy and precision. PMID:9656155

el Walily, A F; Korany, M A; el Gindy, A; Bedair, M F

1998-07-01

393

A Spectrophotometric Study of the Permanganate-Oxalate Reaction: An Analytical Laboratory Experiment  

ERIC Educational Resources Information Center

The spectrophotometric method assists in the study of potassium permanganate-oxalate reaction. Basic analytical techniques and rules are implemented in the experiment, which can also include the examination of other compounds oxidized by permanganate.

Kalbus, Gene E.; Lieu, Van T.; Kalbus, Lee H.

2004-01-01

394

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.  

PubMed

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 (3.0molL(-1)) after 5.0min 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 590nm against the reagent blank. Beer's law was obeyed up to 42.5?gmL(-1) of ruthenium(III) and the optimum concentration range is 7.56-39.81?gmL(-1) of ruthenium(III) as evaluated by Ringbom's plot. Molar absorptivity and Sandell's sensitivity of ruthenium(III)-OMPT complex in chloroform are 2.34×10(3)Lmol(-1) cm(-1) and 0.043?gcm(-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 48h. 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. PMID:23353761

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

2013-04-01

395

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

396

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

397

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 0.170±0.029?molL(-1). PMID:24858263

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

2014-06-15

398

Near UV-near IR Fourier transform spectrometer using the beam-folding position-tracking method based on retroreflectors  

NASA Astrophysics Data System (ADS)

A near UV-near IR Fourier transform spectrometer based on a beam-folding position-tracking method realized by using retroreflectors is reported. The use of retroreflectors maintains all beams in the beam-fold arrangement in parallel with the incident beams. The beam-folding interferometer used for position tracking is arranged to have optical path symmetry with the measurement interferometer in the zero path difference position of the measurement interferometer, and the vertex of the movable retroreflector in the measurement interferometer is arranged very close to the midpoint of the vertices of two movable retroreflectors in the position-tracking interferometer. These measures keep the equivalent optical axis of the position-tracking interferometer well in line with that of the measurement interferometer even with translational misalignments. Therefore, the change in the optical path difference of the position-tracking interferometer is always synchronous to that of the measurement interferometer during the scanning process. That is, the position-tracking error can be suppressed to very small values during a scan. We have demonstrated a UV-near IR Fourier transform spectrometer with a standard quality ball-bearing translation stage achieving a resolution close to the theoretical resolution of ~0.28 cm-1 at the He-Ne laser wavelength when the scan distance reaches the travel distance of over 2 cm. This was achieved without the need for elaborate optics, sophisticated detecting electronics, and high-precision servomotion control.

Wang, Xuzhu; Chan, Robert K. Y.; Cheng, Amelia S. K.

2008-12-01

399

Near UV-near IR Fourier transform spectrometer using the beam-folding position-tracking method based on retroreflectors.  

PubMed

A near UV-near IR Fourier transform spectrometer based on a beam-folding position-tracking method realized by using retroreflectors is reported. The use of retroreflectors maintains all beams in the beam-fold arrangement in parallel with the incident beams. The beam-folding interferometer used for position tracking is arranged to have optical path s