Sample records for uv spectrophotometric method

  1. DETERMINATION OF RIZATRIPTAN IN ITS TABLET DOSAGE FORMS BY UV SPECTROPHOTOMETRIC AND SPECTROFLUORIMETRIC METHODS

    Microsoft Academic Search

    S. Altinoz; G. Ucar; E. Y?ld?z

    2002-01-01

    Rizatriptan is a recently-approved selective 5-HT1B\\/1D agonist which is used in the treatment of migraine headaches. Two spectrophotometric and a spectrofluorimetric methods have been developed for the determination of rizatriptan in its tablet forms. Rizatriptan in its aqueous solutions was determined at the wavelength ranges of 200–350 nm by the spectrophotometric and of 200–450 nm by the spectrofluorimetric methods. Rizatriptan showed an

  2. Development and validation of UV spectrophotometric method to study stress degradation behaviour of rizatriptan benzoate.

    PubMed

    Amolkumar, Kempwade; Ashok, Taranalli; Kiran, Jadhav

    2015-01-01

    Rizatriptan benzoate is a 5 HT 1B/1D receptor agonist which is prescribed for the treatment of migraine. In the present study new, simple, specific ultraviolet spectrophotometric method for rizatriptan benzoate was developed and validated. Forced degradation studies were carried out in acidic, alkaline and neutral pH conditions. The absorbance maxima peak was found to be 224 nm and linearity was observed in the concentration range of 0. 5-2. 5 µg . mL-1 with regression coefficient value of 0. 998 8. The method was validated and found to be precise. The percent recovery for rizatriptan benzoate was found to be 98. 576±0. 202. The bulk drug was found to be stable in neutral and acidic pH conditions but got degraded in 1 N NaOH solution. PMID:25993836

  3. A thermo extraction-UV/Vis spectrophotometric method for total iodine quantification in soils and sediments.

    PubMed

    Gilfedder, B S; Althoff, F; Petri, M; Biester, H

    2007-12-01

    Iodine in soils and sediments is a difficult element to analyze due to its volatility in acidic conditions. Traditionally it has been quantified using neutron activation analysis techniques, which, unfortunately, requires access to a nuclear reactor. We present here a simple method for solid-phase iodine analysis by thermo extraction at 1000 degrees C and quantification by UV/Vis photometry. Samples are combusted in an oxygen stream and trapped in Milli-Q water. The extracts are then quantified by an As3+-Ce4+ spectrometric method whereby iodide catalyzes the oxidation of As3+ to As5+ and reduction of Ce4+ to Ce3+. Three standard reference materials were analyzed with excellent recoveries (97-113%) and RSDs (<5%). Moreover, the detection limit was less than 50 ng absolute iodine with a confidence limit of 95%. When applied to carbonate-rich samples from sediment traps deployed in Lake Constance we found very low iodine levels (0.8-2 mg kg(-1)). Despite the low concentrations, the precision of the method was consistently better than 5% RSD. However, the method needed to be slightly modified for organic and iodine-rich sediments (20-30% organic carbon) from a lake in the Black Forest by increasing the oxygen flow rate and decreasing the combustion time. Using the modified method we were able to achieve RSDs lower than 5%. PMID:17924101

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

    PubMed

    Muralidharan, Selvadurai; Meyyanathan, Subramania Nainar

    2011-01-01

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

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

    PubMed Central

    Muralidharan, Selvadurai; Meyyanathan, Subramania Nainar

    2011-01-01

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

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

    PubMed Central

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

    2013-01-01

    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

  7. Development of the UV spectrophotometric method of Olmesartan medoxomil in bulk drug and pharmaceutical formulation and stress degradation studies

    PubMed Central

    Patel, Jaydeep; Kevin, Garala; Patel, Anjali; Raval, Mihir; Sheth, Navin

    2011-01-01

    A simple, sensitive, specific, spectrophotometric method was developed for the detection of Olmesartan medoxomil (OLM) in bulk and pharmaceutical formulations. The optimum conditions for the analysis of the drug were established. OLM was subjected to stress degradation under different conditions recommended by the International Conference on Harmonization (ICH). The samples so generated were used for degradation studies using the developed method. The ?max of the OLM was found to be 257 nm. The method exhibited high sensitivity, with linearity, in the 2 to 20 ?g/ml range. The lower limit of detection and the limit of quantification were found to be 1.012 ?g/ml and 3.036 ?g/ml, respectively. All the calibration curves demonstrated a linear relationship between the absorbance and concentration, with the correlation coefficient higher than 0.99. The regression equation of the curve was Y = 0.0579x + 0.0006. The precision of the method was found to be 40.043 ± 0.067 against the label claim of 40 mg. The percentage recovery was found to be 101.32 ± 0.452. The sample solution was stable for up to two hours. Hence, it could be concluded that the proposed method would be suitable for the analysis of OLM in bulk and pharmaceutical formulations. PMID:23781428

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

    PubMed

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

    2013-12-01

    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. PMID:24482768

  9. 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

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

    2013-01-01

    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. PMID:24482768

  10. Quantitative analysis of chlorpheniramine maleate and phenylephrine hydrochloride in nasal drops by differential-derivative spectrophotometric, zero-crossing first derivative UV spectrophotometric and absorbance ratio methods

    Microsoft Academic Search

    Nevin Erk

    2000-01-01

    Three simple, rapid and accurate methods are described for the simultaneous determination of chlorpheniramine maleate and phenylephrine hydrochloride in two component mixtures. The first method comprised of measurement of difference absorptivities derivatized in first order of a nasal drops in 0.1 N NaOH relative to that of an equimolar solution in methanol at wavelengths of 271.6 and 250.2 nm, respectively.

  11. Quantitative analysis of chlorpheniramine maleate and phenylephrine hydrochloride in nasal drops by differential-derivative spectrophotometric, zero-crossing first derivative UV spectrophotometric and absorbance ratio methods.

    PubMed

    Erk, N

    2000-11-01

    Three simple, rapid and accurate methods are described for the simultaneous determination of chlorpheniramine maleate and phenylephrine hydrochloride in two component mixtures. The first method comprised of measurement of difference absorptivities derivatized in first order of a nasal drops in 0.1 N NaOH relative to that of an equimolar solution in methanol at wavelengths of 271.6 and 250.2 nm, respectively. The second method, zero-crossing derivative spectrophotometry, is based on recording the first derivative curves and determining each component using the zero-crossing technique. Using first derivative spectrophotometry, the amplitudes in the first derivative spectra at 246.5 and 238.6 nm were selected to simultaneously determine chlorpheniramine maleate and phenylephrine hydrochloride in the mixture. The presence of identical zero-crossing points for pure drugs and nasal drop solutions established the non-interference of the excipients in the absorption at these wavelengths. Absorbance ratio method was also developed for a comparison method. The proposed procedures were successfully applied to the determination of chlorpheniramine maleate and phenylephrine hydrochloride in nasal drops, with a high percentage of recovery, good accuracy and precision. PMID:11095304

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

    PubMed

    Deepali, G; Elvis, M

    2010-10-01

    A rapid, simple, accurate, and economical spectrophotometric method has been developed and validated for the assay of the anti-retroviral agent lamivudine in active pharmaceutical ingredients (API) and in its tablet formulation. The analysis is based on the UV absorbance maxima at about 270nm wavelength of lamivudine, using methanol as solvent. A sample of API was dissolved in methanol to produce a solution containing 10 µg/mL of lamivudine. Similarly, a sample of ground tablets were extracted with methanol, centrifuged, and diluted with the same solvent. The absorbance of the sample preparation was measured at 270 nm against the solvent blank, and the assay was determined by comparing with the absorbance of a similarly prepared 10 µg/mL standard solution of lamivudine. The calibration graph was rectilinear from 5 µg/mL to 15 µg/mL for lamivudine with the correlation coefficient being more than 0.999. The relative standard deviation of the replicate determination was about 0.5%. The percent recovery was within the range of 98%-102%, indicating insignificant interference from the other ingredients in the formulation. The method can be applied for the routine QC quantitation of lamivudine in API and tablet formulation. PMID:21264106

  13. FTIR spectrophotometric methods used for antioxidant activity assay IN MEDICINAL PLANTS

    Microsoft Academic Search

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

    2012-01-01

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

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

    PubMed Central

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

    2010-01-01

    Two UV-spectrophotometric and one reverse phase high performance liquid chromatography methods have been developed for the simultaneous estimation of amlodipine besilate, losartan potassium and hydrochlorothiazide in tablet dosage form. The first UV spectrophotometric method was a determination using the simultaneous equation method at 236.5, 254 and 271 nm over the concentration range 5-25, 10-50 and 5-25 ?g/ml for amlodipine besilate, losartan potassium and hydrochlorothiazide, respectively. The second UV method was a determination using the area under curve method at 231.5-241.5, 249-259 and 266-276 nm over the concentration range of 5-25, 5-25 and 10-50 ?g/ml for amlodipine besilate, hydrochlorothiazide and losartan potassium, respectively. In reverse phase high performance liquid chromatography analysis is carried out using 0.025 M phosphate buffer (pH 3.7):acetonitrile (57:43 v/v) as the mobile phase and Kromasil C18 (4.6 mm i.d×250 mm) column as stationery phase with detection wavelength of 232 nm linearity was obtained in the concentration range of 2-14, 20-140 and 5-40 ?g/ml for amlodipine besilate, losartan potassium and hydrochlorothiazide, respectively. Both UV-spectrophotometric and reverse phase high performance liquid chromatography methods were statistically validated and can be used for analysis of combined dose tablet formulation containing amlodipine besilate, losartan potassium and hydrochlorothiazide. PMID:20582208

  15. UV-Vis spectrophotometrical and analytical methodology for the determination of singlet oxygen in new antibacterials drugs.

    PubMed

    Zoltan, Tamara; Vargas, Franklin; Izzo, Carla

    2007-01-01

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

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

    PubMed Central

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

    2011-01-01

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

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

    PubMed

    Abdelaleem, Eglal Adelhamid; Abdelwahab, Nada Sayed

    2013-01-01

    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

  18. UV Spectrophotometric Determination and Validation of Hydroquinone in Liposome

    PubMed Central

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

    2015-01-01

    The method has been developed and validated for the determination of hydroquinone in liposomal formulation. The samples were dissolved in methanol and evaluated in 293 nm. The validation parameters such as linearity, accuracy, precision, specificity, limit of detection (LOD) and limit of quantitation (LOQ) were determined. The calibration curve was linear in 1-50 µg/mL range of hydroquinone analyte with a regression coefficient of 0.9998. This study showed that the liposomal hydroquinone composed of phospholipid (7.8 %), cholesterol (1.5 %), alpha ketopherol (0.17 %) and hydroquinone (0.5 %) did not absorb wavelength of 293 nm if it diluted 500 times by methanol. The concentration of hydroquinone reached 10 µg/mL after 500 times of dilution. Furthermore, various validation parameters as per ICH Q2B guideline were tested and found accordingly. The recovery percentages of liposomal hydroquinone were found 102 ± 0.8, 99 ± 0.2 and 98 ± 0.4 for 80%, 100% and 120% respectively. The relative standard deviation values of inter and intra-day precisions were <%2. LOD and LOQ were 0.24 and 0.72 µg/mL respectively. PMID:25901154

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

    PubMed Central

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

    2012-01-01

    Purpose: To develop and validate specific and accurate UV spectrophotometric method of cefpodoxime proxetil by using different hydrotropic solubilizing agents. Materials and Methods: The present study deals with spectrophotometric analysis of cefpodoxime proxetil by utilizing 4 different hydrotropic agents such as ammonium acetate (6 M), sodium citrate (1.25 M), sodium gycinate (1 M), sodium chloride (1 M), and urea (1 M). Results: From different hydrotropic agents, urea showed best aqueous solubility of cefpodoxime proxetil. The linearity was observed in the concentration range of 10-120 ?g/ml. The method was validated and found to be precise. Accuracy (percent recovery) for cefpodoxime proxetil was found to be 99.82 ± 0.106. Conclusion: Urea as hydrotropic agent showed best aqueous solubility of cefpodoxime proxetil, which can be used as solubilizing agent. The proposed method is new, simple, safe, eco-friendly, economic, accurate, and cost-effective and can be successfully employed in routine analysis. PMID:23781491

  20. Spectrophotometric Methods for Simultaneous Estimation of Nimesulide and Drotaverine

    Microsoft Academic Search

    Sohan S. Chitlange; Soni Ranjana; Sagar B. Wankhede; Amol A. Kulkarni

    Three simple spectrophotometric methods have been developed for simultaneous estimation of nimesulide and drotaverine from tablet dosage form. Method-I involves, formation of Q-absorbance equation at 349 nm (isoabsorptive point) and 298.5 nm ( ?max of nimesulide); Method-II simultaneous equation method involves the measurement of absorbances at two wavelengths 298.5 nm ( ?max of nimesulide) and 245 nm ( ?max of

  1. A new quantitative and low-cost determination method of nitrate in vegetables, based on deconvolution of UV spectra

    Microsoft Academic Search

    Pham Hoai Nam; Benitez Alejandra; Hommet Frédéric; Bombe Didier; Schoefs Olivier; André Pauss

    2008-01-01

    A new UV-spectrophotometric method for the determination of nitrate in vegetables is presented. The method is based on the spectral deconvolution: UV spectrum of a sample is considered as a linear combination of absorption spectra, named reference spectra. The combination of a small number of spectra of reference allows to reconstitute the shape of UV spectrum of an unknown sample.

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

    PubMed

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

    2014-01-01

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

  3. DEVELOPMENT AND VALIDATION OF RP-HPLC AND ULTRAVIOLET SPECTROPHOTOMETRIC METHODS OF ANALYSIS FOR SIMULTANEOUS DETERMINATION OF PARACETAMOL AND LORNOXICAM IN PHARMACEUTICAL DOSAGE FORMS

    Microsoft Academic Search

    M. V. N. Kumar Talluri; Mukesh K. Bairwa; H. H. Theja Dugga; R. Srinivas

    2012-01-01

    A high performance liquid chromatographic and an UV spectrophotometric method were developed and validated for the simultaneous determination of paracetamol and lornoxicam in pharmaceutical formulations. 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) guidelines. HPLC was carried out by

  4. UV spectrophotometry method for the monitoring of galacto-oligosaccharides production

    Microsoft Academic Search

    Luís G. Dias; Ana C. A. Veloso; Daniela M. Correia; Orlando Rocha; Duarte Torres; Isabel Rocha; Lígia R. Rodrigues; António M. Peres

    2009-01-01

    Monitoring the industrial production of galacto-oligosaccharides (GOS) requires a fast and accurate methodology able to quantify, in real time, the substrate level and the product yield. In this work, a simple, fast and inexpensive UV spectrophotometric method, together with partial least squares regression (PLS) and artificial neural networks (ANN), was applied to simultaneously estimate the products (GOS) and the substrate

  5. Spectrophotometric and LC determination of two binary mixtures containing antihistamins

    Microsoft Academic Search

    Alaa El-Gindy; Samy Emara; Ahmed Mostafa

    2004-01-01

    Several methods are developed for the determination of two binary mixtures containing cyclizine hydrochloride with pyridoxine HCl (mixture (mix.) 1); and cinnarizine with piracetam (mix. 2). The resolution of the two binary mixtures has been accomplished by using numerical spectrophotometric methods as partial least squares (PLS-1) and principal component regression applied to UV spectra of the mixture and graphical spectrophotometric

  6. Simultaneous spectrophotometric determination of atrazine and cyanazine by chemometric methods

    NASA Astrophysics Data System (ADS)

    Zhang, Guowen; Pan, Junhui

    2011-01-01

    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.

  7. SPECTROPHOTOMETRIC DETERMINATION OF AMOXICILLIN IN PHARMACEUTICAL FORMULATIONS

    Microsoft Academic Search

    Kemal UNAL; LMurat PALABIYIK; Elif KARACAN; Feyyaz ONUR

    In present study, three new spectrophotometric methods, original UV spectrophotom etry, first and second order derivative UV spectrophotom etry, were developed for the determination of amoxicillin in pharmaceutica l preparations. In original UV spectrophotom etry, absorbances were measured at 247.0 nm in the zero order UV spectra of the solution of amoxicillin in 0.1N NaOH in the range of 220

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

    E-print Network

    Hwang, Wonjoong

    2011-10-21

    In this study, a reproducible spectrophotometric method was established and applied to measure reductive capacity of various nanomaterials. Reductive capacity had been implicated in the toxicity of nanomaterials, but a ...

  9. Modeling systematic errors: polychromatic sources of Beer-Lambert deviations in HPLC/UV and nonchromatographic spectrophotometric assays.

    PubMed

    Galli, C

    2001-07-01

    It is well established that the use of polychromatic radiation in spectrophotometric assays leads to excursions from the Beer-Lambert limit. This Note models the resulting systematic error as a function of assay spectral width, slope of molecular extinction coefficient, and analyte concentration. The theoretical calculations are compared with recent experimental results; a parameter is introduced which can be used to estimate the magnitude of the systematic error in both chromatographic and nonchromatographic spectrophotometric assays. It is important to realize that the polychromatic radiation employed in common laboratory equipment can yield assay errors up to approximately 4%, even at absorption levels generally considered 'safe' (i.e. absorption <1). Thus careful consideration of instrumental spectral width, analyte concentration, and slope of molecular extinction coefficient is required to ensure robust analytical methods. PMID:11377063

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

    NASA Astrophysics Data System (ADS)

    Rastegarzadeh, Saadat; Pourreza, Nahid; Larki, Arash

    2013-10-01

    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.

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

    PubMed

    Rastegarzadeh, Saadat; Pourreza, Nahid; Larki, Arash

    2013-10-01

    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

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

    Microsoft Academic Search

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

    1952-01-01

    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

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

    Microsoft Academic Search

    Xin-Qing Xu

    2000-01-01

    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

  14. Determination of rhodium: Since the origins until today Spectrophotometric methods.

    PubMed

    Ojeda, C Bosch; Rojas, F Sánchez

    2005-07-15

    Anthropogenic emission of platinum group elements (PGEs) from the abrasion of automotive catalytic converters into the environment has significantly increased. Dust emitted from the catalyst is causing pollution problems of these metals in the future. However, the concentration level of these PGEs is still very low in the nature. The choice of which determination method to use depends on the levels of rhodium, the nature of the sample matrix and the availability of the instrument. In recent years, the development of analytical methods for the determination of rhodium has increased. This review reports the developments in UV-vis absorption spectrometry applied to the determination of rhodium. PMID:18970131

  15. Spectrophotometric analysis of molecular transport in gels

    Microsoft Academic Search

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

    1999-01-01

    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,

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    Five simple, specific, accurate and precise UV-spectrophotometric methods are adopted for the simultaneous determination of Amprolium hydrochloride (AMP) and Ethopabate (ETH), a binary mixture with overlapping spectra, without preliminary separation. The first method is first derivative of the ratio spectra (1DD) for determination of AMP and ETH at 234.7 nm and 306.8 nm respectively with mean percentage recoveries 99.76 ± 0.907 and 100.29 ± 0.842 respectively. The second method is the mean centering of the ratio spectra for determination of AMP and ETH at 238.8 nm and 313 nm respectively with mean percentage recoveries 100.26 ± 1.018 and 99.94 ± 1.286 respectively. The third method is based on dual wavelength selection for determination of AMP and ETH at 235.3 nm & 308 nm and 244 nm & 268.4 nm respectively with mean percentage recoveries 99.30 ± 1.097 and 100.03 ± 1.065 respectively. The fourth method is ratio difference method for determination of AMP and ETH at 239 nm & 310 nm and 239 nm & 313 nm respectively with mean percentage recoveries 99.27 ± 0.892 and 100.40 ± 1.814 respectively. The fifth one is area under the curve (AUC) method where the areas between 235.6-243 nm and 268.3-275 nm are selected for determination of AMP and ETH with mean percentage recoveries 100.35 ± 1.031 and 100.39 ± 0.956 respectively. These methods are tested by analyzing synthetic mixtures of the two drugs and they are applied to their pharmaceutical veterinary preparation. Methods are validated according to the ICH guidelines and accuracy, precision and repeatability are found to be within the acceptable limit.

  17. Determination of ethanol in wine by titrimetric and spectrophotometric dichromate methods: collaborative study.

    PubMed

    Pilone, G J

    1985-01-01

    A dichromate-spectrophotometric method for the determination of ethanol in wine was compared in a collaborative, matched pair study with the AOAC dichromate-titrimetric method, 11.008-11.011. Both methods require distillation of the sample into dichromate. The titrimetric method measures ethanol by titrating the excess dichromate with ferrous ammonium sulfate after conversion of ethanol to acetic acid; the spectrophotometric method directly measures the reduced dichromate formed after oxidation. In addition to comparing the 2 methods, the collaborative study also compared the use of 2 types of assemblies for obtaining the ethanol distillate: the Scott-type, which is used in 11.008-11.011, and the electric Kirk-type. Results of the collaborative study indicated that the repeatability and reproducibility of the official titrimetric method were generally far superior to those of the spectrophotometric method; therefore, adoption of the spectrophotometric method is not recommended. Comparison of titrimetric method results obtained using the 2 types of stills indicated that repeatability and reproducibility were somewhat better when Scott apparatus was used, but measurements using Kirk-type compared well in the range of ethanol concentrations found in table and fortified wines. The Kirk-type distillation apparatus has been adopted official first action as an alternative to Scott apparatus in the dichromate oxidation method for ethanol in wine, 11.008-11.011. PMID:3988696

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

    PubMed Central

    Mahmoud, Ashraf M.

    2009-01-01

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

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

    PubMed Central

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

    2000-01-01

    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. PMID:10653748

  20. Selective Differential Spectrophotometric Methods for Determination of Niclosamide and Drotaverine Hydrochloride

    Microsoft Academic Search

    H. G. Daabees

    2000-01-01

    Differential (?A), second derivative (?D) and third derivative (?D) differential ultraviolet spectrophotometric methods have been presented for the quantitation of niclosamide and drotaverine hydrochloride in pure forms and in their pharmaceutical formulations. For niclosamide, the method is based on measuring ?? A, ? ?D, A ?D of niclosamide in alkaline solutions against their neutral ethanolic solutions as blanks. For drotaverine

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

    NASA Astrophysics Data System (ADS)

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

    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.

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

    PubMed

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

    2015-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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.

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

    PubMed

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

    2014-03-25

    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

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

    NASA Astrophysics Data System (ADS)

    Lotfy, Hayam Mahmoud; Hegazy, Maha Abdel Monem

    2013-09-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Purcell, Dale Kevin

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

  7. AAS and spectrophotometric methods for the determination metoprolol tartrate in tablets

    NASA Astrophysics Data System (ADS)

    Alpdo?an, Güzin; Sungur, Sidika

    1999-11-01

    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.

  8. Rapid spectrophotometric method for determining surface free energy of microalgal cells.

    PubMed

    Zhang, Xinru; Jiang, Zeyi; Li, Mengyin; Zhang, Xinxin; Wang, Ge; Chou, Aihui; Chen, Liang; Yan, Hai; Zuo, Yi Y

    2014-09-01

    Microalgae are one of the most promising renewable energy sources with environmental sustainability. The surface free energy of microalgal cells determines their biofouling and bioflocculation behavior and hence plays an important role in microalgae cultivation and harvesting. To date, the surface energetic properties of microalgal cells are still rarely studied. We developed a novel spectrophotometric method for directly determining the surface free energy of microalgal cells. The principles of this method are based on analyzing colloidal stability of microalgae suspensions. We have shown that this method can effectively differentiate the surface free energy of four microalgal strains, i.e., marine Chlorella sp., marine Nannochloris oculata, freshwater autotrophic Chlorella sp., and freshwater heterotrophic Chlorella sp. With advantages of high-throughput and simplicity, this new spectrophotometric method has the potential to evolve into a standard method for measuring the surface free energy of cells and abiotic particles. PMID:25121721

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

    PubMed

    Stanisz, Beata; Regulska, Katarzyna; Ratajczak, Tomasz

    2012-01-01

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

  10. Simultaneous determination of fosinopril and hydrochlorothiazide in pharmaceutical formulations by spectrophotometric methods

    Microsoft Academic Search

    Nevin Erk

    2002-01-01

    Three new spectrophotometric procedures for the simultaneous determination of fosinopril and hydrochlorothiazide are described. The first method, derivative-differential spectrophotometry, comprised of measurement of the difference absorptivities derivatized in the first-order (?D1) of a tablet extract in 0.1 N NaOH relative to that of an equimolar solution in methanol at wavelengths of 227.6 and 276.4 nm, respectively. The second method, depends

  11. A Spectrophotometric Method for Quantitative Determination of Bromine Using Tris(2-carboxyethyl)phosphine

    Microsoft Academic Search

    Joan Han; Troy Story; Grace Han

    1999-01-01

    A simple spectrophotometric method for quantitative determination of bromine is described. The sample containing bromine is first incubated with an excess of tris(2-carboxyethyl)phosphine (TCEP). One molecule of TCEP is rapidly and irreversibly oxidized to TCEPO (TCEP oxide) by one molecule of bromine. The concentration of residual TCEP is then measured as 2-nitro-5-thiobenzoate produced by reaction with 5,5'-dithiobis(2-nitrobenzoic acid). This method

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

    NASA Astrophysics Data System (ADS)

    Magdy, Nancy; Ayad, Miriam F.

    2015-02-01

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

  13. Simultaneous determination of iron and aluminium by differential kinetic spectrophotometric method and chemometrics

    Microsoft Academic Search

    Yongnian Ni; Chunfang Huang; Serge Kokot

    2007-01-01

    A differential kinetic spectrophotometric method was researched and developed for the simultaneous determination of iron and aluminium in food samples. It was based on the direct reaction kinetics and spectrophotometry of these two metal ions with Chrome Azurol S (CAS) in ethylenediamine–hydrochloric acid buffer (pH 6.3). The results were interpreted with the use of chemometrics. The kinetic runs and the

  14. A Continuous Spectrophotometric Method for Measuring the Activity of Serum Alkaline Phosphatase

    Microsoft Academic Search

    George N. Bowers; Robert B. McComb

    A continuous spectrophotometric method for measuring serum alkaline phosphatase activity is described. The effects of temperature, pH, substrate concentration, type and molarity of the buffer, sample size, cofactors, and inhibitors on the enzymatic hydrolysis of p-nitrophenyl phosphate were studied. The optimal conditions for assay of serum alkaline phosphatase at 300 were found to be 0.75 M 2-amino-2- methyl-1-propanol buffer, pH3o0

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

    Microsoft Academic Search

    T. Machate; A. Kettrup

    1998-01-01

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

  16. Novel spectrophotometric method for detection and estimation of butanol in acetone-butanol-ethanol fermenter.

    PubMed

    Maiti, Sampa; Sarma, Saurabh Jyoti; Brar, Satinder Kaur; Bihan, Yann Le; Drogui, Patrick; Buelna, Gerardo; Verma, Mausam; Soccol, Carlos Ricardo

    2015-08-15

    A new, simple, rapid and selective spectrophotometric method has been developed for detection and estimation of butanol in fermentation broth. The red colored compound, produced during reduction of diquat-dibromide-monohydrate with 2-mercaptoethanol in aqueous solution at high pH (>13), becomes purple on phase transfer to butanol and gives distinct absorption at ?520nm. Estimation of butanol in the fermentation broth has been performed by salting out extraction (SOE) using saturated K3PO4 solution at high pH (>13) followed by absorbance measurement using diquat reagent. Compatibility and optimization of diquat reagent concentration for detection and estimation of butanol concentration in the fermentation broth range was verified by central composite design. A standard curve was constructed to estimate butanol in acetone-ethanol-butanol (ABE) mixture under optimized conditions. The spectrophotometric results for butanol estimation, was found to have 87.5% concordance with the data from gas chromatographic analysis. PMID:25966390

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

    PubMed

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

    2015-02-25

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    PubMed

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

    2015-02-25

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

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

    NASA Astrophysics Data System (ADS)

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

    2008-08-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Abdellatef, Hisham E.

    2007-03-01

    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.

  2. Kinetic spectrophotometric method for the determination of ramipril in pharmaceutical formulations.

    PubMed

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

    2005-01-01

    The objective of this research was to develop a kinetic spectrophotometric method for determination of ramipril in pure form and pharmaceutical formulations. The method was based on the reaction of carboxylic acid group of the drug with a mixture of potassium iodate (KIO3) and potassium iodide (KI) in aqueous medium at room temperature. The reaction is followed spectrophotometrically by measuring the increase in absorbance at 352 nm as a function of time. The initial-rate and fixed-time methods were adopted for constructing the calibration curves. Both the calibration curves were linear in the concentration range of 10.0-70.0 microg mL(-1). The detection limits were 0.02 microg mL(-1) and 0.15-microg mL(-1) for initial rate and fixed time methods, respectively. The proposed methods are validated statistically and through recovery studies. The point and interval hypothesis tests have been performed confirming that there is no significant difference between the proposed methods and the reference method. The experimental true bias of all samples is less than +/- 2%. The methods have been successfully applied to the determination of ramipril in tablets and capsules. PMID:16354016

  3. Determination of niobium in rocks by an isotope dilution spectrophotometric method

    USGS Publications Warehouse

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

    1970-01-01

    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.

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

    PubMed Central

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

    2010-01-01

    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

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

    PubMed

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

    2010-10-01

    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

  6. A Spectrophotometric Method for Quantitative Determination of Bromine Using Tris(2-carboxyethyl)phosphine

    NASA Astrophysics Data System (ADS)

    Han, Joan; Story, Troy; Han, Grace

    1999-07-01

    A simple spectrophotometric method for quantitative determination of bromine is described. The sample containing bromine is first incubated with an excess of tris(2-carboxyethyl)phosphine (TCEP). One molecule of TCEP is rapidly and irreversibly oxidized to TCEPO (TCEP oxide) by one molecule of bromine. The concentration of residual TCEP is then measured as 2-nitro-5-thiobenzoate produced by reaction with 5,5'-dithiobis(2-nitrobenzoic acid). This method has a lower detection limit and is more convenient than the standard procedure of bromine assay by reaction with potassium iodide followed by titration of the liberated iodine with thiosulfate.

  7. Simultaneous determination of fosinopril and hydrochlorothiazide in pharmaceutical formulations by spectrophotometric methods.

    PubMed

    Erk, Nevin

    2002-03-01

    Three new spectrophotometric procedures for the simultaneous determination of fosinopril and hydrochlorothiazide are described. The first method, derivative-differential spectrophotometry, comprised of measurement of the difference absorptivities derivatized in the first-order (DeltaD(1)) of a tablet extract in 0.1 N NaOH relative to that of an equimolar solution in methanol at wavelengths of 227.6 and 276.4 nm, respectively. The second method, depends on the application ratio spectra derivative spectrophotometric method to resolve the interferance due to spectral overlapping. The analytical signals were measured at 237.9, 243.8 nm for fosinopril and 262.4, 269.3 and 278.6 nm for hydrochlorothiazide in the binary mixture, in the first derivative of the ratio spectra of the mixture solutions in methanol. Calibration graphs were established for 4.0-50.0 microg ml(-1) fosinopril and 2.0-14.0 microg ml(-1) hydrochlorothiazide in binary mixture. The third method, absorbance ratio method, the determination of fosinopril and hydrochlorothiazide was performed by using the absorbances read at 210.0, 219.5 and 271.7 nm in the zero-order spectra of their mixture. The developed methods were compared with absorbance ratio method. Application of the suggested procedures were successfully applied to the determination of this compound in synthetic mixtures and in pharmaceutical preparations, with high percentage of recovery, good accuracy and precision. PMID:11836054

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

    PubMed Central

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

    2013-01-01

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

  9. Development and Validation of Simultaneous Spectrophotometric Methods for Drotaverine Hydrochloride and Aceclofenac from Tablet Dosage Form

    PubMed Central

    Shah, S. A.; Shah, D. R.; Chauhan, R. S.; Jain, J. R.

    2011-01-01

    Two simple spectrophotometric methods have been developed for simultaneous estimation of drotaverine hydrochloride and aceclofenac from tablet dosage form. Method I is a simultaneous equation method (Vierodt's method), wavelengths selected are 306.5 and 276 nm. Method II is the absorbance ratio method (Q-Analysis), which employs 298.5 nm as ?1 and 276 nm as ?2 (?max of AF) for formation of equations. Both the methods were found to be linear between the range of 8-32 ?g/ml for drotaverine and 10-40 ?g/ml for aceclofenac. The accuracy and precision were determined and found to comply with ICH guidelines. Both the methods showed good reproducibility and recovery with % RSD in the desired range. The methods were found to be rapid, specific, precise and accurate and can be successfully applied for the routine analysis of drotaverine and aceclofenac in their combined tablet dosage form. PMID:22457554

  10. Development and validation of simultaneous spectrophotometric methods for drotaverine hydrochloride and aceclofenac from tablet dosage form.

    PubMed

    Shah, S A; Shah, D R; Chauhan, R S; Jain, J R

    2011-05-01

    Two simple spectrophotometric methods have been developed for simultaneous estimation of drotaverine hydrochloride and aceclofenac from tablet dosage form. Method I is a simultaneous equation method (Vierodt's method), wavelengths selected are 306.5 and 276 nm. Method II is the absorbance ratio method (Q-Analysis), which employs 298.5 nm as ?(1) and 276 nm as ?(2) (?max of AF) for formation of equations. Both the methods were found to be linear between the range of 8-32 ?g/ml for drotaverine and 10-40 ?g/ml for aceclofenac. The accuracy and precision were determined and found to comply with ICH guidelines. Both the methods showed good reproducibility and recovery with % RSD in the desired range. The methods were found to be rapid, specific, precise and accurate and can be successfully applied for the routine analysis of drotaverine and aceclofenac in their combined tablet dosage form. PMID:22457554

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

    PubMed

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

    2008-09-15

    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

  12. Biocatalytic spectrophotometric method to detect paracetamol in water samples.

    PubMed

    Méndez-Albores, Alia; Tarín, Cristina; Rebollar-Pérez, Georgette; Dominguez-Ramirez, Lenin; Torres, Eduardo

    2015-08-24

    A biocatalytic methodology based on the quantification of the laccase inhibition during the oxidation of a standard substrate ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) for the indirect determination of paracetamol in drinking water has been developed. The method displayed a fast response time (20 s), and high selectivity to paracetamol in presence of interfering substances such as naproxen, estradiol, ketoprofen, sulfamethoxazole, and diclofenac. The limit of detection (LOD) and limit of quantification (LOQ) were noticed to be 0.55 µM and 8.3 µM, respectively. By comparing the catalytic constants value KM and kcat for ABTS oxidation in the absence and presence of various concentrations of paracetamol, a competitive-type inhibition was disclosed. On the other hand, the close value between Ki and KM indicates similar binding affinity of the enzyme to ABTS and paracetamol corroborated by docking studies. The methodology was successfully applied to real water samples, presenting an interesting potential for further development of a biosensor to paracetamol detection. PMID:26121020

  13. [Spectra derivative kalman filter method for simultaneous spectrophotometric determination of phenol, 2-chlorophenol and 2,4-dichlorophenol].

    PubMed

    Wang, Qiang; Ma, Pei-sheng; Hu, Kai-tang; Jia, Qing-zhu

    2007-03-01

    A novel and stable spectra derivative Kalman filter UV spectrophotometric method was proposed, and applied to the simultaneous determination of ternary mixture of phenol, 2-chlorophenol and 2,4 dichlorophenol successfully. The reasons for using spectra derivative is that it contains more information including absorbance and its change with wavelength; the obviously different signals can be caught more conveniently at the position of absorbent overlap. The noise from experiment and the errors from transfer model can be solved by Kalman filter. Calibration set with 30 standard solutions (range of 1-10 mg x L(-1)) and 61 wavelengths (260-290 m, 0.5 nm slit width) was used for each sample. The exact value of absorbance derivative was obtained from regressed simulation for the extended 8th order polynomial, and the standard work matrix of derivative spectra Kalman filter was performed from partial least-squares method. The linear discrete Kalman filter was applied to the test. The recovery experiment showed that the derivative spectra Kalman filter simultaneous determination of mixture for phenol, 2-chlorophenol and 2,4 dichlorophenol is not only exact, but also stable. PMID:17554922

  14. Extractive spectrophotometric methods for the assay of sildenafil citrate (Viagra) in pure form and in pharmaceutical formulations

    Microsoft Academic Search

    N. D Dinesh; P Nagaraja; N. M Made Gowda; K. S Rangappa

    2002-01-01

    Two simple and sensitive extractive spectrophotometric methods for the determination of sildenafil citrate (SC) are proposed. The methods are based on the formation of ion-association complexes of sildenafil citrate with bromocresol green (BCG, method A) and with chromoxane cyanine R (CCR, method B) in aqueous acidic buffer. The complex species, extractable to chloroform phase, were quantitatively measured at 415 and

  15. Simple spectrophotometric methods for estimation of aceclofenac from bulk and formulations

    PubMed Central

    Bose, A; Dash, PP; Sahoo, MK

    2010-01-01

    Two simple, precise and accurate visible spectrophotometric methods were developed for the estimation of Aceclofenac in bulk drug and in pharmaceutical formulations. The proposed methods were indirect and based on determination of aceclofenac after its reaction with either (p-dimethylaminocinnamaldehyde or 3-Methyl-2-benzothiazolinone hydrazine hydrochloride and measuring the chromogen at the ?max by 658 and 592, respectively. Beers law obeyed in the concentration range of 1-200 ?g/ml for method A and 1-100 ?g/ml for method B. The accuracy of the methods was determined by recovery studies. The methods showed good reproducibility and recovery with relative standard deviation (in %) less than 2. The methods were found to be simple, economical, accurate and reproducible and can be used for routine analysis of Aceclofenac in bulk drug and in pharmaceutical formulations. PMID:23781418

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

    NASA Astrophysics Data System (ADS)

    Fayez, Yasmin Mohammed

    2014-11-01

    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.

  17. Simple spectrophotometric methods for estimation of aceclofenac from bulk and formulations.

    PubMed

    Bose, A; Dash, Pp; Sahoo, Mk

    2010-10-01

    Two simple, precise and accurate visible spectrophotometric methods were developed for the estimation of Aceclofenac in bulk drug and in pharmaceutical formulations. The proposed methods were indirect and based on determination of aceclofenac after its reaction with either (p-dimethylaminocinnamaldehyde or 3-Methyl-2-benzothiazolinone hydrazine hydrochloride and measuring the chromogen at the ?max by 658 and 592, respectively. Beers law obeyed in the concentration range of 1-200 ?g/ml for method A and 1-100 ?g/ml for method B. The accuracy of the methods was determined by recovery studies. The methods showed good reproducibility and recovery with relative standard deviation (in %) less than 2. The methods were found to be simple, economical, accurate and reproducible and can be used for routine analysis of Aceclofenac in bulk drug and in pharmaceutical formulations. PMID:23781418

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

    PubMed Central

    Rahman, Nafisur; Haque, Sk Manirul

    2008-01-01

    Four simple, rapid and sensitive spectrophotometric methods have been proposed for the determination of enalapril maleate in pharmaceutical formulations. The first method is based on the reaction of carboxylic acid group of enalapril maleate with a mixture of potassium iodate (KIO3) and iodide (KI) to form yellow colored product in aqueous medium at 25 ± 1°C. The reaction is followed spectrophotometrically by measuring the absorbance at 352 nm. The second, third and fourth methods are based on the charge transfer complexation reaction of the drug with p-chloranilic acid (pCA) in 1, 4-dioxan-methanol medium, 2, 3-dichloro 5, 6-dicyano 1, 4-benzoquinone (DDQ) in acetonitrile-1,4 dioxane medium and iodine in acetonitrile-dichloromethane medium. Under optimized experimental conditions, Beer’s law is obeyed in the concentration ranges of 2.5–50, 20–560, 5–75 and 10–200 ?g mL?1, respectively. All the methods have been applied to the determination of enalapril maleate in pharmaceutical dosage forms. Results of analysis are validated statistically. PMID:19609388

  19. Novel spectrophotometric method for selective determination of compounds in ternary mixtures (dual wavelength in ratio spectra).

    PubMed

    Saad, Ahmed S

    2015-08-01

    A simple selective spectrophotometric method for determination of compounds in ternary mixture was developed by combining the resolution power of two well-known methods that are commonly used for binary mixtures; namely ratio difference method and dual wavelength. The new method (dual wavelength in ratio spectra) was successfully applied for the determination of a ternary mixture of betamethasone dipropionate (BM), clotrimazole (CT) and benzyl alcohol (BA) in pure powder form and in their pharmaceutical preparation. The difference in amplitudes (?P) in the ratio spectra at 252.0 and 258.0nm (?P252.0-258.0nm) corresponds to BM, while ?P266.8-255.4nm and ?P254.2-243.5nm corresponds to CT and BA, respectively. The method was validated as per the USP 2005 guidelines. The developed method can be used in quality control laboratories for routine analysis of compounds in ternary mixtures. PMID:25847787

  20. Langley method of calibrating UV filter radiometers

    NASA Astrophysics Data System (ADS)

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

    2000-02-01

    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 radiometer remains in the field during calibration. Difficulties arise as a result of changing ozone optical depth during the Langley event and the breakdown of the Beer-Lambert law over the finite filter band pass since optical depth changes rapidly with wavelength. The Langley calibration of the radiometers depends critically upon the spectral characterization of each channel and on the wavelength and absolute calibration of the extraterrestrial spectrum used. Results of Langley calibrations for two UV-MFRSRs at Mauna Loa, Hawaii were compared to calibrations using two National Institute of Standards and Technology (NIST) traceable lamps. The objectives of this study were to compare Langley calibration factors with those from standard lamps and to compare field-of-view effects. The two radiometers were run simultaneously: one on a Sun tracker and the other in the conventional shadow-band configuration. Both radiometers were calibrated with two secondary 1000 W lamp, and later, the spectral response functions of the channels were measured. The ratio of Langley to lamp calibration factors for the seven channels from 300 nm to 368 nm using the shadow-band configuration ranged from 0.988 to 1.070. The estimated uncertainty in accuracy of the Langley calibrations ranged from ±3.8% at 300 nm to ±2.1% at 368 nm. For all channels calibrated with Central Ultraviolet Calibration Facility (CUCF) lamps the estimated uncertainty was ±2.5% for all channels.

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

    SciTech Connect

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

    2013-02-25

    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.

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

    PubMed Central

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

    2009-01-01

    A simple, accurate and precise spectrophotometric method has been developed for simultaneous estimation of escitalopram oxalate and clonazepam in combined dosage form. Simultaneous equation method is employed for simultaneous determination of escitalopram oxalate and clonazepam from combined dosage forms. In this method, the absorbance was measured at 238 nm for escitalopram oxalate and 273 nm for clonazepam. Linearity was observed in range of 5-100 ?g/ml and 5-50 ?g/ml for escitalopram and clonazepam respectively. Recovery studies confirmed the accuracy of proposed method and results were validated as per ICH guidelines. The method can be used for routine quality control of pharmaceutical formulation containing escitalopram and clonazepam. PMID:20376230

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

    PubMed

    Kakde, R B; Satone, D D

    2009-11-01

    A simple, accurate and precise spectrophotometric method has been developed for simultaneous estimation of escitalopram oxalate and clonazepam in combined dosage form. Simultaneous equation method is employed for simultaneous determination of escitalopram oxalate and clonazepam from combined dosage forms. In this method, the absorbance was measured at 238 nm for escitalopram oxalate and 273 nm for clonazepam. Linearity was observed in range of 5-100 mug/ml and 5-50 mug/ml for escitalopram and clonazepam respectively. Recovery studies confirmed the accuracy of proposed method and results were validated as per ICH guidelines. The method can be used for routine quality control of pharmaceutical formulation containing escitalopram and clonazepam. PMID:20376230

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

    Microsoft Academic Search

    Wies?awa Misiuk

    2005-01-01

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

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

    PubMed

    Rahman, Nafisur; Hoda, Md Nasrul

    2002-06-01

    A new simple, sensitive and reproducible spectrophotometric method for the determination of nifedipine in pure and dosage forms has been proposed. It is based on the reduction of nifedipine with Zn/NNH4Cl, followed by coupling with N-methyl-1,4-benzoquinoneimine--the oxidation product of 4-(methylamino)phenol, to give a chromophore which absorbed maximally at 525 nm. The experimental conditions were optimised and Beer's law was obeyed over the concentration range of 5-175 microg ml(-1). The molar absorptivity, detection limit, recovery and RSD were found to be 1.9 x 10(3) l mol(-1) cm(-1), 1.1 microg ml(-1), 99.7-100.5% and 0.3-0.8%, respectively. The proposed method was compared favourably with the official B.P. method. PMID:12088057

  6. pKa determinations of xanthene derivates in aqueous solutions by multivariate analysis applied to UV-Vis spectrophotometric data.

    PubMed

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

    2011-09-01

    Xanthenes form to an important class of dyes which are widely used. Most of them present three acid-base groups: two phenolic sites and one carboxylic site. Therefore, the pKa determination and the attribution of each group to the corresponding pKa value is a very important feature. Attempts to obtain reliable pKa through the potentiometry titration and the electronic absorption spectrophotometry using the first and second orders derivative failed. Due to the close pKa values allied to strong UV-Vis spectral overlap, multivariate analysis, a powerful chemometric method, is applied in this work. The determination was performed for eosin Y, erythrosin B, and bengal rose B, and also for other synthesized derivatives such as 2-(3,6-dihydroxy-9-acridinyl) benzoic acid, 2,4,5,7-tetranitrofluorescein, eosin methyl ester, and erythrosin methyl ester in water. These last two compounds (esters) permitted to attribute the pKa of the phenolic group, which is not easily recognizable for some investigated dyes. Besides the pKa determination, the chemometry allowed for estimating the electronic spectrum of some prevalent protolytic species and the substituents effects evaluation. PMID:21550841

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

    PubMed

    Joubert, Elizabeth; Manley, Marena; Botha, Mariza

    2008-01-01

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

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

    PubMed Central

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

    2009-01-01

    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. PMID:23675147

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

    PubMed Central

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

    2009-01-01

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

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

    PubMed Central

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

    2011-01-01

    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. PMID:23781455

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

    PubMed

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

    2015-05-01

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

  12. A new second-derivative spectrophotometric method for the determination of permethrin in shampoo.

    PubMed

    Kazemipour, Maryam; Noroozian, Ebrahim; Saber Tehrani, Mohammad; Mahmoudian, Massoud

    2002-11-01

    Permethrin, a highly effective insecticide agent, has been widely used for the pest control in agriculture and the treatment of lice in human. A fast and reliable method for the determination of permethrin was highly desirable to support formulation screening and quality control. A second-derivative UV spectroscopic method was developed for the determination of permethrin in the shampoo dosage form after extraction. The second-derivative spectrum recorded between 250 and 310 nm, and a zero-crossing technique for second-derivative measurement at 279 nm was selected. It is found that the selectivity and sensitivity of the method to be in desirable range. In comparison with the direct UV method, second-derivative UV spectroscopy eliminates the interference from UV absorbing excipients. This method is also fast and economical in comparison with the more time-consuming GC method regularly used for formulation screening and quality control and can be used routinely by any laboratory possessing a spectrophotometer with a derivative accessory. The linear concentration ranges were 0.25-1.5 ppm (D2=0.00042Conc.+0.0018, r=0.9972, n=10). Between day of CV%method for determination in quality control. PMID:12408929

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

    PubMed Central

    Amin, Alaa S.; Kassem, Mohammed A.

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    Four simple, accurate, sensitive and precise spectrophotometric methods were developed and validated for simultaneous determination of Troxerutin (TXN) and Carbazochrome (CZM) in their bulk powders, laboratory prepared mixtures and pharmaceutical dosage forms. Method A is first derivative spectrophotometry (D1) where TXN and CZM were determined at 294 and 483.5 nm, respectively. Method B is first derivative of ratio spectra (DD1) where the peak amplitude at 248 for TXN and 439 nm for CZM were used for their determination. Method C is ratio subtraction (RS); in which TXN was determined at its ?max (352 nm) in the presence of CZM which was determined by D1 at 483.5 nm. While, method D is mean centering of the ratio spectra (MCR) in which the mean centered values at 300 nm and 340.0 nm were used for the two drugs in a respective order. The two compounds were simultaneously determined in the concentration ranges of 5.00-50.00 ?g mL-1 and 0.5-10.0 ?g mL-1 for TXN and CZM, respectively. The methods were validated according to the ICH guidelines and the results were statistically compared to the manufacturer's method.

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

    PubMed

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

    2015-03-15

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

  16. 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)

    Lotfy, Hayam Mahmoud; Abdel-Monem Hagazy, Maha

    2012-10-01

    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.

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

    PubMed

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

    2010-03-01

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

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

    PubMed

    Moustafa, H; Fayez, Y

    2014-12-10

    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

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

    NASA Astrophysics Data System (ADS)

    Moustafa, H.; Fayez, Y.

    2014-12-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

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

    PubMed

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

    2014-05-01

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

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

    PubMed

    Xia, Zhenzhen; Ni, Yongnian; Kokot, Serge

    2013-12-15

    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

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

    NASA Astrophysics Data System (ADS)

    Gouda, Ayman A.; Malah, Zakia Al

    2013-03-01

    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.

  4. Pregabalin and tranexamic Acid evaluation by two simple and sensitive spectrophotometric methods.

    PubMed

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

    2015-01-01

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

  5. Application of chemometric methods to the simultaneous kinetic spectrophotometric determination of iodate and periodate based on consecutive reactions

    Microsoft Academic Search

    Yongnian Ni; Yong Wang

    2007-01-01

    A kinetic spectrophotometric method for the simultaneous determination of iodate and periodate in mixtures was proposed. The method is established on the different kinetic behaviours of the analytes which react with starch–iodide in the presence of sodium chloride in sulfuric acid medium. The kinetic data were collected from 260 to 900 nm every 10 nm, within a time range of 0–180 s at

  6. Comparative study of spectrophotometric methods manipulating ratio spectra: an application on pharmaceutical binary mixture of cinnarizine and dimenhydrinate.

    PubMed

    Lamie, Nesrine T

    2015-04-15

    Four simple, specific, accurate and precise spectrophotometric methods are developed and validated for simultaneous determination of cinnarizine (CIN) and dimenhydrinate (DIM) in a binary mixture with overlapping spectra, without preliminary separation. The first method is dual wavelength spectrophotometry (DW), the second is a ratio difference spectrophotometric one (RD) which measures the difference in amplitudes between 250 and 270 nm of ratio spectrum, the third one is novel constant center spectrophotometric method (CC) and the fourth method is mean centering of ratio spectra (MCR). The calibration curve is linear over the concentration range of 4-20 and 10-45 ?g/ml for CIN and DIM, 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. The validity of results was assessed by applying standard addition technique. The results obtained were found to agree statistically with those obtained by a reported method, showing no significant difference with respect to accuracy and precision. PMID:25677532

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

    PubMed Central

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

    2012-01-01

    Background: Paracetamol and lornoxicam in combined tablet dosage form are available in the market. This combination is used to treat inflammatory diseases of the joints, osteoarthritis and sciatica. Spectrophotometric and high performance liquid chromatography (HPLC) methods have been reported for their simultaneous estimation in tablet dosage form in specific solvent. This paper presents simple, accurate and reproducible spectrophotometric method for simultaneous determination of paracetamol and lornoxicam in tablet dosage form in different dissolution media. The reported method is helpful in determination of paracetamol and lornoxicam during dissolution study. Materials and Methods: Simple, sensitive, accurate and economical spectrophotometric method based on an absorption correction equation was developed for the estimation of paracetamol and lornoxicam simultaneously in tablet dosage form in different dissolution media at different pH. Results: Paracetamol showed absorption maxima at 243 nm in 0.1N HCland phosphate buffer pH 6.8, while lornoxicam showed absorption maxima at 374 nm in 0.1N HCland phosphate buffer pH 6.8. The linearity was obtained in the concentration range of 4-12 ?g/ml for paracetamol and 4-16 ?g/ ml for lornoxicam. Discussion: The concentrations of the drugs were determined by an absorption correction equation method. The results of analysis have been validated statistically by recovery studies. PMID:23781487

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

    PubMed Central

    Shishehbore, Masoud Reza; Aghamiri, Zahra

    2014-01-01

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

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

    SciTech Connect

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

    1993-12-01

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

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

    PubMed Central

    Akhoundi-Khalafi, Ali Mohammad; Shishehbore, Masoud Reza

    2015-01-01

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

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

    Microsoft Academic Search

    Alaa El-Gindy

    2005-01-01

    Three methods are developed for the simultaneous determination of diprophylline (DP), phenobarbitone (PH) and papaverine hydrochloride (PP). The chromatographic method depends on a high performance liquid chromatographic (HPLC) separation on a reversed-phase C18 column with a mobile phase consisting of 0.02 M potassium dihydrogen phosphate, pH 3.5—acetonitrile (55:45 v\\/v). Quantitation was achieved with UV detection at 210 nm based on peak area. The

  12. Estimation of phytotoxic aluminum in soil solution using three spectrophotometric methods

    SciTech Connect

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

    1987-09-01

    In the current investigation three spectrophotometric techniques -8-hydroxyquinoline, aluminon, and ferron- were compared for their ability to estimate phytotoxic Al in soil solution. Soil solution Al reacting with 8-hydroxyquinoline in 15 s, ferron in 30 s, and aluminon in 30 min were related to root and shoot growth of subterranean clover (Trifolium subterraneum L. cv. Mt. Barket) and switchgrass (Panicum virgatum L. cv. Cave-in-Rock) in limed and unlimed treatments of 10 acidic subsoil horizons. Across all 10 soils the amount of Al reacting with 8-hydroxyquinoline was generally the lowest, and that reacting with ferron the highest, although overlap among methods did occur. Manganese interference in several of the soil solutions limited the utility of the ferron method. The amounts of Al reacting with 8-hydroxyquinoline and aluminon were significantly related (P < 0.05) to root and shoot growth limitations exhibited by subterranean clover and switch-grass. Activities of Al/sup 3 +/ (a/sub Al/sup 3 +//) calculated from the GEOCHEM program using the Al reacting with 8-hydroxyquinoline and aluminon as the Al inputs were generally the best predictors of root and shoot growth.

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

    PubMed

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

    2014-10-15

    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

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    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.

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

    PubMed

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

    2003-01-01

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

  16. Simultaneous determination of iron and aluminium by differential kinetic spectrophotometric method and chemometrics.

    PubMed

    Ni, Yongnian; Huang, Chunfang; Kokot, Serge

    2007-09-19

    A differential kinetic spectrophotometric method was researched and developed for the simultaneous determination of iron and aluminium in food samples. It was based on the direct reaction kinetics and spectrophotometry of these two metal ions with Chrome Azurol S (CAS) in ethylenediamine-hydrochloric acid buffer (pH 6.3). The results were interpreted with the use of chemometrics. The kinetic runs and the visible spectra of the complex formation reaction were studied between 540 and 750 nm every 30 s over a total period of 285 s. A set of synthetic metal mixture samples was used to build calibrations models. These were based on the spectral and kinetic two-way data matrices, which were processed separately by the radial basis function-artificial neural network (global RBF-ANN) method. The prediction performance of these models was poorer than that from the combined kinetic-spectral three-way array, which was similarly processed by the same method (% relative prediction error (RPE(T))=5.6). These results demonstrate that improved predictions can be obtained from the data array, which has more information, and that appropriate chemometrics methods can enhance analytical performance of simple techniques such as spectrophotometry. Other chemometrics models were then applied: N-way partial least squares (NPLS), parallel factor analysis (PARAFAC), back propagation-artificial neural network (BP-ANN), single radial basis function-artificial neural network (RBF-ANN), and principal component neural network (PC-RBF-ANN). There was no substantial difference between the methods with the overall %RPE(T) range being 5.0-5.8. These two values corresponded to the NPLS and BP-ANN models, respectively. The proposed method was applied for the determination of iron and aluminium in some commercial food samples with satisfactory results. PMID:17870283

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

    PubMed

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

    2015-04-01

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

  18. UV-Vis spectrophotometric analysis and light irradiance through hot-pressed and hot-pressed-veneered glass ceramics.

    PubMed

    Dias, Myrna Carvalho; Piva, Evandro; de Moraes, Rafael Ratto; Ambrosano, Gláucia Maria Bovi; Sinhoreti, Mário Alexandre Coelho; Correr-Sobrinho, Lourenço

    2008-01-01

    This study evaluated the irradiance of curing units through core and veneered hot-pressed ceramics as well as the transmittance of these materials. Discs of 0.7, 1.4 and 2 mm in thickness of Empress (EMP) and Empress Esthetic (EST), and 0.8 (n=5) and 1.1 mm (n=5) thickness of Empress 2 (E2) were obtained. For E2, two of the 0.8-mm-thick discs were covered with dentin (1.2- and 1.4-mm-thick) and two with dentin + enamel (1.5-mm-thick). The 1.1-mm-thick specimens were submitted to the same veneering procedures. Specimens were evaluated by UV-Vis transmittance analysis and the percentage of transmittance was recorded. Irradiance through each specimen was evaluated with a quartz-tungsten-halogen (QTH), used in continuous or intermittent exposure modes, or a blue light-emitting diode (LED). Data were analyzed by Dunnett's test, ANOVA and Tukey's test at 5% significance level. Exposure through ceramic decreased the irradiance for all ceramics. Irradiance through EST was significantly higher than through EMP. For E2, reduction in irradiance depended on the core and/or veneer thickness. The QTH intermittent mode showed higher irradiance than the continuous mode, and both showed higher irradiance than LED. The ceramic significantly influenced irradiance and transmittance, which were found to decrease with the increase in thickness. PMID:18949290

  19. Simultaneous spectrophotometric determination of phenanthridine, phenanthridinone and phenanthridine N-oxide using multivariate calibration methods

    Microsoft Academic Search

    Mohammad-Hossein Sorouraddin; Kaveh Amini; Abdolhossein Naseri; Mohammad-Reza Rashidi

    2010-01-01

    The multivariate calibration methods, partial least squares (PLS) and principle component regression (PCR) have been used\\u000a to determine phenanthridine, phenanthridinone and phenanthridine N-oxide in spiked human plasma samples. Resolution of binary\\u000a and ternary mixtures of analytes with minimum sample pre-treatment and without analyte separation has been successfully achieved\\u000a analyzing the UV spectral data. The net analyte signal (NAS) concept was

  20. [Spectrophotometric evaluation of hemolysis tests].

    PubMed

    Unger, G; Ellinger, C; Haberer, K

    1984-01-01

    A quantitative spectrophotometric method for measuring the hemolysis degree of PVC-biomaterials by potassium hexacyanoferrate (III) and potassium cyanide is presented. By means of this method the physiological valuation of biomaterials proved more exact as to their contents of hemolytically acting substances. In order to define the maximum permissible degree of hemolysis from biomaterials further studies will be necessary. UV- and IR spectrograms of the 70 degrees C and 121 degrees C extracts from biomaterials indicated the presence of substances not yet identified till now. These substances couldn't be ascribed any specific biological effects. An extraction at 121 degrees C is recommended in order to detect hemolytically acting substances. PMID:6516504

  1. Comparative study of novel versus conventional two-wavelength spectrophotometric methods for analysis of spectrally overlapping binary mixture.

    PubMed

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

    2015-09-01

    Smart spectrophotometric methods have been applied and validated for the simultaneous determination of a binary mixture of chloramphenicol (CPL) and prednisolone acetate (PA) without preliminary separation. Two novel methods have been developed; the first method depends upon advanced absorbance subtraction (AAS), while the other method relies on advanced amplitude modulation (AAM); in addition to the well established dual wavelength (DW), ratio difference (RD) and constant center coupled with spectrum subtraction (CC-SS) methods. Accuracy, precision and linearity ranges of these methods were determined. Moreover, selectivity was assessed by analyzing synthetic mixtures of both drugs. The proposed methods were successfully applied to the assay of drugs in their pharmaceutical formulations. No interference was observed from common additives and the validity of the methods was tested. The obtained results have been statistically compared to that of official spectrophotometric methods to give a conclusion that there is no significant difference between the proposed methods and the official ones with respect to accuracy and precision. PMID:25909908

  2. A clean method for flow injection spectrophotometric determination of cyclamate in table sweeteners

    Microsoft Academic Search

    Fábio R. P. Rocha; Eva Ródenas-Torralba; Ángel Morales-Rubio; Miguel de la Guardia

    2005-01-01

    A flow system based on the multicommutation is proposed for fast and clean determination of cyclamate. The procedure exploits the reaction of cyclamate with nitrite in acidic medium and the spectrophotometric determination of the excess of nitrite by iodometry. The flow system was designed with a set of solenoid micro-pumps to minimize reagent consumption and waste generation. The detection limit

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

    SciTech Connect

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

    1988-07-01

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

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

    PubMed

    Ashour, Safwan; Bayram, Roula

    2015-04-01

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

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

    NASA Astrophysics Data System (ADS)

    Ashour, Safwan; Bayram, Roula

    2015-04-01

    New, accurate, sensitive and reliable kinetic spectrophotometric method for the assay of moxifloxacin hydrochloride (MOXF) in pure form and pharmaceutical formulations has been developed. The method involves the oxidative coupling reaction of MOXF with 3-methyl-2-benzothiazolinone hydrazone hydrochloride monohydrate (MBTH) in the presence of Ce(IV) in an acidic medium to form colored product with lambda max at 623 and 660 nm. The reaction is followed spectrophotometrically by measuring the increase in absorbance at 623 nm as a function of time. The initial rate and fixed time methods were adopted for constructing the calibration curves. The linearity range was found to be 1.89-40.0 ?g mL-1 for initial rate and fixed time methods. The limit of detection for initial rate and fixed time methods is 0.644 and 0.043 ?g mL-1, respectively. Molar absorptivity for the method was found to be 0.89 × 104 L mol-1 cm-1. Statistical treatment of the experimental results indicates that the methods are precise and accurate. The proposed method has been applied successfully for the estimation of moxifloxacin hydrochloride in tablet dosage form with no interference from the excipients. The results are compared with the official method.

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

    PubMed

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

    2009-11-15

    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 approximately 4 micromol/L by UV and <0.4 micromol/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 is easy to perform and provides clear signal readouts indicative of the presence of phosgene precursors. The utility of this method was demonstrated by the qualitative determination of residual triphosgene during the production of poly(bisphenol-A carbonate). PMID:19782219

  7. 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

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

    2011-01-01

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

  8. Extractive spectrophotometric methods for the assay of sildenafil citrate (Viagra) in pure form and in pharmaceutical formulations.

    PubMed

    Dinesh, N D; Nagaraja, P; Made Gowda, N M; Rangappa, K S

    2002-06-10

    Two simple and sensitive extractive spectrophotometric methods for the determination of sildenafil citrate (SC) are proposed. The methods are based on the formation of ion-association complexes of sildenafil citrate with bromocresol green (BCG, method A) and with chromoxane cyanine R (CCR, method B) in aqueous acidic buffer. The complex species, extractable to chloroform phase, were quantitatively measured at 415 and 460 nm for methods A and B, respectively. Beer's law was obeyed in the SC concentration range 1.25-25 mug ml(-1) with a limit of detection 0.16 mug ml(-1) and 1.5-60 mug ml(-1) with a limit of detection 0.18 mug ml(-1), respectively, for methods A and B. The methods have been successfully applied to the analysis of bulk drug and its tablets. No interference was observed from common pharmaceutical adjuvants. PMID:18968678

  9. Spectrophotometric quantitative determination of cilazapril and hydrochlorothiazide in tablets by chemometric methods.

    PubMed

    Dinç, Erdal; Baleanu, Dumitru

    2002-10-15

    Four chemometric methods were applied to simultaneous determination of cilazapril and hydrochlorothiazide in tablets. Classical least-square (CLS), inverse least-square (ILS), principal component regression (PCR) and partial least-squares (PLS) methods do not need any priori graphical treatment of the overlapping spectra of two drugs in a mixture. For all chemometric calibrations a concentration set of the random mixture consisting of the two drugs in 0.1 M HCI and methanol (1:1) was prepared. The absorbance data in the UV-Vis spectra were measured for the 15 wavelength points (from 222 to 276 nm) in the spectral region 210-290 nm considering the intervals of deltalambda = 4 nm. The calibration of the investigated methods involves only absorbance and concentration data matrices. The developed calibrations were tested for the synthetic mixtures consisting of two drugs and using the Maple V software the chemometric calculations were performed. The results of the methods were compared each other as well as with HPLC method and a good agreement was found. PMID:12367697

  10. Simultaneous spectrophotometric determination of the three structural isomers of cresol using multivariate regression methods.

    PubMed

    Moneeb, Marwa Said; Hewala, Ismail Ibrahim; Elmongy, Hatem Abdelfattah; Wahbi, Abdel-Aziz Mohamed

    2015-07-01

    The simultaneous determination of the structural isomers of cresol was carried out using UV spectrophotometry by applying the principle component regression (PCR) and partial least squares (PLS) regression methods. Different concentration levels of cresol isomers were determined in their mixtures by construction of a partial factorial calibration design at four levels. Both multivariate calibration models were constructed using the correlation between the concentration and absorbance data matrices in the spectral region 283-305nm. The methods were validated by analyzing an independent validation set solutions of the same compounds. The methods were found to be accurate and precise as indicated by the mean % recovery (99.96-100.41%) and % relative standard deviation (0.15-0.72%), respectively. The methods were applied to the determination of cresol isomers in a topical veterinary preparation. The methods were proved to be applicable to the determination of the three cresol isomers without prior separation procedures, despite of the extensive spectral overlap of such compounds. PMID:26142523

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

    PubMed

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

    2012-01-01

    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

  12. Spectrophotometric estimation of ethamsylate and mefenamic Acid from a binary mixture by dual wavelength and simultaneous equation methods.

    PubMed

    Goyal, Anju; Singhvi, I

    2008-01-01

    Two simple, accurate, economical and reproducible spectrophotometric methods for simultaneous estimation of two-component drug mixture of ethamsylate and mefenamic acid in combined tablet dosage form have been developed. The first developed method involves formation and solving of simultaneous equation using 287.6 nm and 313.2 nm as two wavelengths. Second developed method is based on two wavelength calculation. Two wavelengths selected for estimation of ethamsylate were 274.4 nm and 301.2 nm while that for mefenamic acid were 304.8 nm and 320.4 nm. Both the developed methods obey Beer's law in the concentration ranges employed for the respective methods. The results of analysis were validated statistically and by recovery studies. PMID:20390094

  13. Spectrophotometric Estimation of Ethamsylate and Mefenamic Acid from a Binary Mixture by Dual Wavelength and Simultaneous Equation Methods

    PubMed Central

    Goyal, Anju; Singhvi, I.

    2008-01-01

    Two simple, accurate, economical and reproducible spectrophotometric methods for simultaneous estimation of two-component drug mixture of ethamsylate and mefenamic acid in combined tablet dosage form have been developed. The first developed method involves formation and solving of simultaneous equation using 287.6 nm and 313.2 nm as two wavelengths. Second developed method is based on two wavelength calculation. Two wavelengths selected for estimation of ethamsylate were 274.4 nm and 301.2 nm while that for mefenamic acid were 304.8 nm and 320.4 nm. Both the developed methods obey Beer's law in the concentration ranges employed for the respective methods. The results of analysis were validated statistically and by recovery studies. PMID:20390094

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

    PubMed

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

    2005-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2008-08-01

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

  16. Derivative spectrophotometric method for simultaneous determination of zofenopril and fluvastatin in mixtures and pharmaceutical dosage forms.

    PubMed

    Stolarczyk, Mariusz; Ma?lanka, Anna; Apola, Anna; Rybak, Wojciech; Krzek, Jan

    2015-09-01

    Fast, accurate and precise method for the determination of zofenopril and fluvastatin was developed using spectrophotometry of the first (D1), second (D2), and third (D3) order derivatives in two-component mixtures and in pharmaceutical preparations. It was shown, that the developed method allows for the determination of the tested components in a direct manner, despite the apparent interference of the absorption spectra in the UV range. For quantitative determinations, "zero-crossing" method was chosen, appropriate wavelengths for zofenopril were: D1 ?=270.85nm, D2 ?=286.38nm, D3 ?=253.90nm. Fluvastatin was determined at wavelengths: D1 ?=339.03nm, D2 ?=252.57nm, D3 ?=258.50nm, respectively. The method was characterized by high sensitivity and accuracy, for zofenopril LOD was in the range of 0.19-0.87?gmL(-1), for fluvastatin 0.51-1.18?gmL(-1), depending on the class of derivative, and for zofenopril and fluvastatin LOQ was 0.57-2.64?gmL(-1) and 1.56-3.57?gmL(-1), respectively. The recovery of individual components was within the range of 100±5%. For zofenopril, the linearity range was estimated between 7.65?gmL(-1) and 22.94?gmL(-1), and for fluvastatin between 5.60?gmL(-1) and 28.00?gmL(-1). PMID:25863461

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

    PubMed

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

    2015-02-01

    Three sensitive, selective, and precise stability indicating methods for the determination of the X-ray contrast agent, diatrizoate sodium (DTA), in the presence of its acidic degradation product (highly cytotoxic 3,5 diamino metabolite) and in pharmaceutical formulation were developed and validated. The first method is a first derivative (D1) spectrophotometric one, which allows the determination of DTA in the presence of its degradate at 231.2 nm (corresponding to zero crossing of the degradate) over a concentration range of 2-24 ?g/mL with mean percentage recovery 99.95±0.97%. The second method is the first derivative of the ratio spectra (DD1) by measuring the peak amplitude at 227 nm over the same concentration range as D1 spectrophotometric method, with mean percentage recovery 99.99±1.15%. The third method is a TLC-densitometric one, where DTA was separated from its degradate on silica gel plates using chloroform:methanol:ammonium hydroxide (20:10:2 by volume) as a developing system. This method depends on quantitative densitometric evaluation of thin layer chromatogram of DTA at 238 nm over a concentration range of 4-20 ?g/spot, with mean percentage recovery 99.88±0.89%. The selectivity of the proposed methods was tested using laboratory-prepared mixtures. The proposed methods have been successfully applied to the analysis of DTA in pharmaceutical dosage forms without interference from other dosage form additives. The results were statistically compared with the official US pharmacopeial method. No significant difference for either accuracy or precision was observed. PMID:25456658

  18. Simultaneous kinetic spectrophotometric determination of periodate and iodate based on their reaction with pyrogallol red in acidic media by chemometrics methods

    Microsoft Academic Search

    J Ghasemi; S Saaidpour; A. A Ensafi

    2004-01-01

    The univariate and multivariate calibration methods were applied for the simultaneous determination of iodate and periodate in water. The method is based on the reaction of periodate and iodate with pyrogallol red in sulfuric acid media. The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of pyrogallol red at 470nm. The calibration curve was linear over the concentration

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

    PubMed

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

    2012-01-01

    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

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

    PubMed Central

    2012-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    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.

  2. Comparison of HTC method and UV/persulphate method to determine colloidal organic carbon in seawater

    NASA Astrophysics Data System (ADS)

    Wang, Jiang-Tao; Zhao, Wei-Hong; Tan, Li-Ju; Zhang, Zheng-Bin

    2000-03-01

    The application of cross-flow ultrafiltration (CFF) techniques to separate colloidal organic carbon (COC) from truly dissolved organic carbon(TDOC) was investigated; COC and TDOC were determined by the high-temperature combustion method(HTC) and UV/persulphate method. It was found that CFF can quantitatively separate COC from seawater. The determination results by the HTC and UV/persulphate method for COC and TDOC showed little difference, which suggested that the oxidation efficiency of the two methods are identical. Colloidal particles have no remarkable influence on the oxidation efficiency of the UV/persulphate method.

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

    NASA Technical Reports Server (NTRS)

    Dupraw, W. A.

    1972-01-01

    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.

  4. In vitro assessment of phagocytosis of bovine collagen by human monocytes/macrophages using a spectrophotometric method.

    PubMed

    Ciapetti, G; Verri, E; Granchi, D; Cenni, E; Gamberini, S; Benetti, D; Mian, M; Pizzoferrato, A

    1996-09-01

    The use of a wound dressing with covering and haemostatic properties significantly improves wound healing. In this study, a lyophilized bovine collagen sponge used for the treatment of wounds and ulcerae has been tested in a cell culture system. Phagocytosis of collagen fragments by human blood monocytes/macrophages has been investigated. For the assessment of collagen ingestion by mononuclear phagocytes, a picrosirius dye specific for collagen molecules has been used. By adapting this histochemical technique to microplate cell culture system, replicate monocyte cultures are assayed. Collagen content is determined by evaluating spectrophotometrically at 540 nm the absorbance of a sirius red/picric acid solution. Using this simple and sensitive method, the phagocytosis of bovine collagen by LPS-stimulated monocytes/macrophages has been ascertained. PMID:8866032

  5. Liquid Chromatographic and Spectrophotometric Determination of Phenazopyridine Hydrochloride, Ampicilline Trihydrate, and Nitrofurantoine in Pharmaceutical Preparations

    Microsoft Academic Search

    ?. M. Palab?y?k; F. Onur

    2004-01-01

    The present work describes two new liquid chromatographic (LC) methods and three new spectrophotometric methods for the simultaneous determination of phenazopyridine hydrochloride (PHEN), ampicilline trihydrate (AMP), and nitrofurantoine (NIT) in their binary combinations. In the LC methods, a Nucleosil C8 column with a mobile phase composed of methanol–acetonitril–water (42:42:16, v\\/v\\/v) with ultraviolet (UV) detection at 260 nm was used for a

  6. Spectrophotometric probe

    DOEpatents

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

    1994-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Ashour, Safwan; Bayram, Roula

    2012-12-01

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

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

    PubMed Central

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

    2010-01-01

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

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

    PubMed

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

    2014-12-01

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

  10. A comparative study of smart spectrophotometric methods for simultaneous determination of a skeletal muscle relaxant and an analgesic in combined dosage form.

    PubMed

    Salem, Hesham; Mohamed, Dalia

    2015-04-01

    Six simple, specific, accurate and precise spectrophotometric methods were developed and validated for the simultaneous determination of the analgesic drug; paracetamol (PARA) and the skeletal muscle relaxant; dantrolene sodium (DANT). Three methods are manipulating ratio spectra namely; ratio difference (RD), ratio subtraction (RS) and mean centering (MC). The other three methods are utilizing the isoabsorptive point either at zero order namely; absorbance ratio (AR) and absorbance subtraction (AS) or at ratio spectrum namely; amplitude modulation (AM). The proposed spectrophotometric procedures do not require any preliminary separation step. The accuracy, precision and linearity ranges of the proposed methods were determined. The selectivity of the developed methods was investigated by analyzing laboratory prepared mixtures of the drugs and their combined dosage form. Standard deviation values are less than 1.5 in the assay of raw materials and capsules. The obtained results were statistically compared with each other and with those of reported spectrophotometric ones. The comparison showed that there is no significant difference between the proposed methods and the reported methods regarding both accuracy and precision. PMID:25594211

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

    PubMed

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

    2013-01-01

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

  12. Novel spectrophotometric method for the determination of aluminum in soda drinks packed in cans and plastic bottles.

    PubMed

    Francisco, Barbara Bruna A; Caldas, Luiz Fernando S; Brum, Daniel M; Cassella, Ricardo J

    2010-09-15

    In the present work, a new spectrophotometric method was developed for the determination of aluminum in soda drinks packed in different materials. Reaction among Al(III), phenylfluorone (PF) and cetylpyridinium chloride (CPC) in slightly alkaline medium was explored for this purpose. The method was optimized regarding to its chemical parameters in order to establish better conditions in terms of sensitivity and selectivity. The results obtained showed that the concentration of CPC presented remarkable influence on the sensitivity and acted as a sensitizer for the studied system. The possible interferences of some metallic cations were evaluated and the cations Cu(II), Mn(II), and Zn(II) presented noticed interference on the Al(III) signal. So, their interference was eliminated by using EDTA with minimum loss of sensitivity. The results obtained in the determination of total aluminum in soda drinks by the developed methodology were not statistically different from those obtained by electrothermal atomic absorption spectrometry. In the optimized conditions the method presented a linear range of 5-100 microg L(-1). The limits of detection and quantification were 0.81 and 2.7 microg L(-1), respectively. The methodology was successfully applied in the determination of aluminum in 10 samples of soda drinks packed in cans and plastic bottles. PMID:20605324

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  14. Accelerated UV test methods and selection criteria for encapsulants of photovoltaic modules

    Microsoft Academic Search

    Michael D. Kempe

    2008-01-01

    Photovoltaic modules are exposed to extremely harsh conditions of heat, humidity, high voltage, mechanical stress, thermal cycling and ultraviolet (UV) radiation. The current qualification tests (e.g. IEC 61215) do not require UV exposure high enough to evaluate a 20+ year lifespan. Methods to quickly test the UV durability of photovoltaic materials are needed. In considering encapsulant materials, the initial performance

  15. Validation and application of high-performance liquid chromatographic and spectrophotometric methods for simultaneous estimation of nebivolol and hydrochlorothiazide: a novel approach to multivariate calibrations by R-Software Environment.

    PubMed

    Gowda, Nagaraj; Panghal, Surender; Vipul, Kalamkar; Rajshree, Mashru

    2009-01-01

    A fast, simple reversed-phase HPLC method and two spectrophotometric methods based on principal component regression and partial least squares calibrations were developed for determination of nebivolol (NEB) and hydrochlorothiazide (HCTZ) in formulations without prior separation or masking. The HPLC assay utilized a Phenomenex-Luna RP-18(2) 250 x 4.6 mm, 5 microm column with acetonitrile--0.03% aqueous formic acid, pH 3.3 (65 + 35, v/v), mobile phase at a flow rate of 1.0 mL/min, and UV detection at 277 nm. The retention times of NEB and HCTZ were 2.133 and 2.877 min, respectively. The total run time was < 4 min. Chemometric calibrations were constructed by using an absorption data matrix corresponding to a concentration data matrix, with measurements in the range of 231-310 nm (Delta lambda = 1 nm) in their zero-order spectra using 16 samples in a training set. The chemometric numerical computations were obtained by using R-Software Environment (Version 2.1.1). The proposed methods were validated for various International Conference on Harmonization regulatory parameters like linearity, range, accuracy, precision, robustness, LOD, LOQ, and HPLC system suitability. Laboratory-prepared mixtures and commercial tablet formulations were successfully analyzed using the developed methods. All results were acceptable and confirmed that the method is suitable for its intended use. PMID:19916373

  16. Spectrophotometric monitoring of nimesulide photodegradation by a combined hard–soft multivariate curve resolution-alternative least square method

    Microsoft Academic Search

    Bahram Hemmateenejad; Katayoun Javidnia; Mehdi Saeidi-Boroujeni

    2008-01-01

    Nimesulide, a Cox-2 inhibitor anti-inflammatory drug, is a light sensitive compound and its biological activity is decreased upon photodegradation. The photodegradation kinetic of nimesulide was investigated spectrophotometrically using multivariate curve resolution analysis to overcome spectral overlapping of reactant and degradation products. The absorbance spectra of the nimesulide methanolic solution, exposed to daily sunlight, were recorded at different times. Three absorbing

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

    Microsoft Academic Search

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

    2001-01-01

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

  18. Spectrophotometric quantitative determination of cilazapril and hydrochlorothiazide in tablets by chemometric methods

    Microsoft Academic Search

    Erdal Dinç; Dumitru Baleanu

    2002-01-01

    Four chemometric methods were applied to simultaneous determination of cilazapril and hydrochlorothiazide in tablets. Classical least-square (CLS), inverse least-square (ILS), principal component regression (PCR) and partial least-squares (PLS) methods do not need any priori graphical treatment of the overlapping spectra of two drugs in a mixture. For all chemometric calibrations a concentration set of the random mixture consisting of the

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

    Microsoft Academic Search

    Alaa El-Gindy; Samy Emara; Ahmed Mostafa

    2005-01-01

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

  20. Molecular absorption spectrophotometric method for the determination of phosphorus in biodiesel

    Microsoft Academic Search

    Eva Lúcia Cardoso Silveira; Lilia Basílio de Caland; Matthieu Tubino

    2011-01-01

    A molecular absorption method is proposed for the determination of phosphorus in biodiesel. The samples are mineralized using an ashing procedure at 550°C followed by dissolution of the residue. The analytical procedure is based on the formation of a blue molybdenum complex. 1-amino-2-naphthol-4-sulfonicacidis used as reducing agent. The method was applied to biodiesel samples prepared from soy, canola and sunflower

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

    PubMed

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

    2015-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  3. Stability-indicating spectrophotometric and densitometric methods for determination of aceclofenac.

    PubMed

    el-Saharty, Y S; Refaat, M; el-Khateeb, S Z

    2002-05-01

    Three methods were developed for the determination of aceclofenac in the presence of its degradation product, diclofenac. In the first method, third-derivative spectrophotometry (D3) is used. The D3 absorbance is measured at 283 nm where its hydrolytic degradation product diclofenac does not interfere. The suggested method shows a linear relationship in the range of 4-24 micrograms mL-1 with mean percentage accuracy of 100.05 +/- 0.88. This method determines the intact drug in the presence of up to 70% degradation product with mean percentage recovery of 100.42 +/- 0.94. The second method depends on ratio-spectra first-derivative (RSD1) spectrophotometry at 252 nm for aceclofenac and at 248 nm for determination of degradation product over concentration ranges of 4-32 micrograms mL-1 for both aceclofenac and diclofenac with mean percentage accuracy of 99.81 +/- 0.84 and 100.19 +/- 0.72 for pure drugs and 100.17 +/- 0.94 and 99.73 +/- 0.74 for laboratory-prepared mixtures, respectively. The third method depends on the quantitative evaluation of thin-layer chromatography of aceclofenac using chloroform:methanol: ammonia (48:11.5:0.5 v/v/v) as a mobile phase. Chromatograms were scanned at 274 and 283 nm for aceclofenac and diclofenac, respectively. The method determined aceclofenac and diclofenac in concentration ranges of 2-10 and 1-9 micrograms spot-1 with mean percentage accuracy of 100.20 +/- 1.03 and 100.14 +/- 0.98 for pure drugs and 99.77 +/- 0.74 and 100.07 +/- 0.78 for laboratory-prepared mixtures, respectively. This method retains its accuracy in the presence of up to 80% degradation product for the studied drug. The suggested procedures were checked using laboratory-prepared mixtures and were successfully applied for the analysis of their pharmaceutical preparation. The validity of the proposed methods was further assessed by applying a standard addition technique. The obtained results agreed statistically with those obtained by the reported method. PMID:12098846

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

    NASA Astrophysics Data System (ADS)

    Gao, Ling; Ren, Shouxin

    2005-10-01

    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 matrices and wavelet packet transform, respectively. In the KPLS method, the size of the kernel matrix is only dependent on the number of samples, thus the method was suitable for the data matrix with many wavelengths and fewer samples. Wavelet packet representations of signals provide a local time-frequency description, thus in the wavelet packet domain, the quality of the noise removal can be improved. In the WPTPLS by optimization, wavelet function and decomposition level were selected as Daubeches 12 and 5, respectively. Experimental results showed both methods to be successful even where there was severe overlap of spectra.

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

    E-print Network

    Hwang, Wonjoong

    2011-10-21

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

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

    Microsoft Academic Search

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

    2008-01-01

    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

  7. Comparison of spectrophotometric and HPLC methods for determination of lipid peroxidation products in rat brain tissues

    Microsoft Academic Search

    M. ?urfinová; M. Brechtlová; B. Líška; Ž. Barošková

    2007-01-01

    Two methods for determination of lipid peroxidation (LPX) products in rat brain homogenates were compared. The thiobarbituric\\u000a acid (TBA) test and HPLC assay for analysis of malondialdehyde (MDA) were applied. Rat brain homogenate dissolved in tris(hydroxymethyl)aminomethane\\u000a hydrochloride (Tris-HCl) was mixed with TBA and H3PO4 and heated at 100°C to form colored complex that was extracted into butanol. No significant differences

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

    PubMed

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

    2014-01-01

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

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

    PubMed Central

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

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

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

    PubMed

    Mohamed, Heba M

    2014-10-28

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

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

    PubMed Central

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

    2012-01-01

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

  13. Spectrophotometric analysis of molecular transport in gels.

    PubMed

    Dunmire, E N; Plenys, A M; Katz, D F

    1999-02-01

    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, 0.3x10x40 mm. Molecules of interest are identified and concentrations quantitated via analysis of spectrophotometric absorbance peaks relative to background absorbance of the gel. Thus, concentration profiles are obtained as functions of both position and time. Test data are fitted to a diffusion model via nonlinear least-squares regression. Precision and accuracy of the method were assessed via analysis of several test molecules and gels: (1) 30 mg/ml nonoxynol-9 (N9), contained in 1% sodium alginate gel cross-linked with 2.5 mM calcium chloride, permeating standardized, reconstituted bovine cervical mucus (BCM); (2) 2.5 mg/ml sodium fluorescein, contained in and permeating 10 mg/ml and 100 mg/ml gelatin gels; and (3) 1.0 mg/ml sodium ganciclovir, contained in and permeating 10 mg/ml sodium hyaluronate gel. Diffusion coefficients for (1) and (3) were 3.8x10-7 and 54.1x10-7 cm2/s, respectively. All measurements of diffusion coefficients, partition coefficients, and solute loads obtained in this study were highly repeatable (most C.V.'s<8%). The mean diffusion coefficient for (2) was within 3% of values predicted from theory for the 100 mg/ml gel; the mean partition coefficient for (3) was within 2% of the expected value. This new technique is simpler than many traditional ones in that it does not require labeling of test molecules nor changes in refractive index of target materials. It is particularly well-suited to situations in which the target material is a gel, because no stirring of the target is necessary. PMID:9971891

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

    Microsoft Academic Search

    Changquan Qiu; Fan Xu; Quang Trong Nguyen; Zhenghua Ping

    2005-01-01

    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

  15. Simultaneous spectrophotometric determination of Fe(III), Al(III) and Cu(II) by partial least-squares calibration method

    NASA Astrophysics Data System (ADS)

    Safavi, A.; Abdollahi, H.; Mirzajani, R.

    2006-01-01

    A spectrophotometric method for simultaneous determination of Fe(III), Al(III) and Cu(II) using Alizarin Red S as a chelating agent was developed. The parameters controlling behavior of the system were investigated and optimum conditions were selected. A partial least-squares multivariate calibration method was used for the analysis of ternary mixtures of Fe(III), Al(III) and Cu(II) over the range of 450-6000, 140-4000 and 450-15000 ng ml -1, respectively. Absorbance data were taken between 400 and 800 nm. Applying this method to simultaneous determination of these metal ions in several synthetic alloy solutions with total relative standard error of less than 5% validated the proposed method.

  16. 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

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

    2014-09-15

    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

  17. Determination of clotiazepam by HPLC with spectrophotometric and amperometric detection

    Microsoft Academic Search

    Isabel Barbero Rodriguez; Jesús Rodriguez Procopio; Lucas Hernandez Hernandez

    1987-01-01

    Summary  Spectrophotometric and amperometric detectors were compared for the determination of clotiazepam by HPLC. Methanol-water (6040) containing 0.01 mol\\/l ammonium acetate and methanol-water (7030) containing 0.01 mol\\/l acetate buffer pH 4 were used as mobile phase in the spectrophotometric and amperometric detection, respectively. The minimum detectability for the spectrophotometric detection was 20 ng injected and the method was applied for the

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

    Microsoft Academic Search

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

    2010-01-01

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

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

    PubMed

    Niazi, Ali; Khorshidi, Neda; Ghaemmaghami, Pegah

    2015-01-25

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

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

    NASA Astrophysics Data System (ADS)

    Niazi, Ali; Khorshidi, Neda; Ghaemmaghami, Pegah

    2015-01-01

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

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

    PubMed Central

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

    2014-01-01

    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

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

    NASA Astrophysics Data System (ADS)

    Yang, Li

    2014-09-01

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

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

    PubMed

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

    2010-07-15

    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

  4. 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)

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

    2014-12-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    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.

  6. 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)

    Al Okab, Riyad Ahmed

    2013-02-01

    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.

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

    PubMed

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

    2008-01-01

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

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

    PubMed Central

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

    2013-01-01

    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

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

    Microsoft Academic Search

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

    2000-01-01

    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

  10. Measurements of continuous spectra of atmospheric absorption coefficients from UV to NIR via optical method

    Microsoft Academic Search

    S. Mogo; V. E. Cachorro; M. Sorribas; A. de Frutos; R. Fernández

    2005-01-01

    In this study we extend from the visible to the UV a traditional method for studying the radiative properties of black carbon. We apply this measuring possibility to a practical study carried out in the Southern Iberian Peninsula during summer 2004. Using an optical technique based on the integrating sphere method, absorption coefficients, sigmaa, were determined in the visible and

  11. Measurements of continuous spectra of atmospheric absorption coefficients from UV to NIR via optical method

    Microsoft Academic Search

    S. Mogo; V. E. Cachorro; M. Sorribas; A. de Frutos; R. Fernández

    2005-01-01

    In this study we extend from the visible to the UV a traditional method for studying the radiative properties of black carbon. We apply this measuring possibility to a practical study carried out in the Southern Iberian Peninsula during summer 2004. Using an optical technique based on the integrating sphere method, absorption coefficients, ?a, were determined in the visible and

  12. Multiwavelength spectrophotometric determination of acid dissociation constants of ionizable drugs

    Microsoft Academic Search

    R. I. Allen; K. J. Box; J. E. A. Comer; C. Peake; K. Y. Tam

    1998-01-01

    A multiwavelength spectrophotometric approach has been developed to determine acid dissociation constants (pKa values) of sparingly soluble drug compounds. UV absorption spectra of the drug solution are acquired using a versatile device based on a fiber optics dip probe, a light source and a photodiode array (PDA) detector while the pH and the ionic strength of the chemical system is

  13. UV protection by clothing: an intercomparison of measurements and methods.

    PubMed

    Gies, H P; Roy, C R; McLennan, A; Diffey, B L; Pailthorpe, M; Driscoll, C; Whillock, M; McKinlay, A F; Grainger, K; Clark, I; Sayre, R M

    1997-09-01

    In an attempt to reduce the incidence of skin cancer, cancer foundations have run educational campaigns which encourage the general population to limit their solar UVR exposures. An important part of these campaigns, in particular in Australia, but also more recently in Europe and the U.S., has been the adoption of protective measures such as sunscreens, hats, sunglasses and clothing. The protective properties of fabrics and clothing against ultraviolet radiation (UVR) have been known for some time, but recently there has been considerable interest in quantifying the degree of protection. This has been generated, in part, by the requirements for occupational protection for outdoor workers as well as the provision of UVR protection for the recreational market. The quantification of UVR protection has been laboratory based using in vitro test methods. Development of a standard test method has become an important part of the testing process, and this paper presents results from an intercomparison involving five independent testing laboratories. Agreement is good, in particular for samples with protection factors below 50. Technical difficulties and sources of errors associated with the measurements are discussed. PMID:9287086

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

    E-print Network

    Dunham, Maitreya

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

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

    NASA Astrophysics Data System (ADS)

    Wang, Jingang; Xu, Cheng; Sun, Jiaxiang

    2014-06-01

    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.

  16. Searching for triatomines. A new method for field search using UV light.

    PubMed

    Catalá, Silvia

    2010-10-01

    Detection of triatomine bugs within a house is essential for the estimation of Chagas disease transmission risk and for evaluating the success of insecticidal control attempts. Small residual populations could represent an important risk but are difficult to detect by time manual sampling. Faecal marks from triatomines are clearly detectable with an ultraviolet (UV) light on most of the materials frequently used in rural buildings. A new method for finding triatomines is proposed here, based on the unexplored property of faeces to fluoresce when exposed to UV light. PMID:20457119

  17. Simultaneous spectrophotometric determination of iron, nickel and cobalt in micellar media by using direct orthogonal signal correction-partial least squares method.

    PubMed

    Zarei, K; Atabati, M; Malekshabani, Z

    2006-01-18

    A very simple and selective spectrophotometric method for simultaneous determination of iron(II), nickel(II) and cobalt(II) based on formation of their complexes with 1-(2-pyridylazo)-2-naphtol (PAN) in micellar media is described. Although the complexes of Fe(II), Ni(II) and Co(II) with reagent show a spectral overlap, they have been simultaneously determined by partial least squares (PLS) with and without preprocessing step using direct orthogonal signal correction (DOSC). The linear range was 0.30-4.50 microg ml(-1) for Co(II), 0.20-3.00 microg ml(-1) for Ni(II) and 0.30-5.00 microg ml(-1) for Fe(II). The results obtained by the PLS and DOSC-PLS were statistically compared. Interference effects of common anions and cations were studied and the proposed method was also applied satisfactorily to the determination of Fe(II), Ni(II) and Co(II) in synthetic samples. PMID:17723355

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    PubMed

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

    2015-04-15

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

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

    PubMed

    Felis, E; Miksch, K

    2015-01-01

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

  1. Development and validation of spectrophotometric and high-performance column liquid chromatographic methods for the simultaneous determination of dienogest and estradiol valerate in pharmaceutical preparations.

    PubMed

    Ca?layan, Mehmet Gökhan; Palabiyik, Ismail Murat; Onur, Feyyaz

    2010-01-01

    Simultaneous determination of dienogest (DIE) and estradiol valerate (EST) in sugar-coated tablets was performed by using HPLC and spectrophotometry. In HPLC, the separation was achieved on an ACE C8 column using the mobile phase acetonitrile-NH4NO3 (0.03 M, pH 5.4; 70 + 30, v/v) at a flow rate of 2 mL/min. The detection wavelength was 280 nm, and cyproterone acetate was selected as an internal standard. The linearity range was 3.0-45.0 microg/mL for DIE and 18.0-100.0 microg/mL for EST. As spectrophotometric methods, two chemometric methods, principal component regression and partial least-squares, were developed. In the chemometric techniques, the concentration data matrix was prepared by using mixtures containing these drugs in methanol-water (3 + 1, v/v). The absorbance data matrix corresponding to the concentration data matrix in these methods was obtained by the measurement of absorbances in their zero-order spectra; then, the calibration was obtained by using the data matrix for the prediction of unknown concentrations of DIE and EST in their binary mixture. Working ranges were found as 2.0-24.0 microg/mL for DIE and 20.0-270.0 microg/mL EST in the methods. These three developed methods were validated and successfully applied to a pharmaceutical preparation, a sugar-coated tablet, and the results were compared with each other. PMID:20629388

  2. A simple spectrophotometric method for the determination of trace levels of molybdenum using N,N'-bis(2-hydroxy-5-bromo-benzyl)1,2 diaminopropane.

    PubMed

    Kara, Derya; Karada?, Cennet

    2015-08-01

    The present work describes a selective, rapid and economical spectrophotometric method for the determination of molybdenum using N,N'-bis(2-hydroxy-5-bromo-benzyl)1,2 diaminopropane. Molybdenum(VI) reacts with N,N'-bis(2-hydroxy-5-bromo-benzyl)1,2 diaminopropane to form a stable 1:1 yellow complex with an absorption maximum at 342nm. The reaction is completed within 10min and the absorbance of the molybdenum complex remains stable for at least 1week at room temperature. The effective molar absorption coefficient at 342nm was 9.6×10(3)Lmol(-1)cm(-1). Under optimal conditions, the complex obeys Beer's law from 0 to 9.9?gmL(-1). The relative standard deviation was 0.08% (for 11 samples, each containing 6?gmL(-1) molybdenum). Under the optimum conditions, the detection limit (3?) was 17.7?gL(-1) for molybdenum without any preconcentration. The precision was determined from 30 results obtained for 4.80?gmL(-1) Mo(VI); the mean value of a molybdenum(VI) was 4.83?gml(-1) with a standard derivation of 0.002?gml(-1) molybdenum(VI). PMID:25835378

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

    PubMed

    Alessandri, Stefano; Ieri, Francesca; Romani, Annalisa

    2014-01-29

    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

  4. A one-step photolithography method for fabrication of a staggered herringbone mixer using inclined UV lithography

    Microsoft Academic Search

    Sunghoon Baek; Simon Song

    2011-01-01

    We present a facile method for fabrication of a staggered herringbone mixer using inclined UV lithography, in which the incident UV angle is not perpendicular to the wafer. With this fabrication method, we were able to fabricate staggered herringbone ridges and microchannels simultaneously. As a result, complicated photolithography processes were reduced to a single step. Herein, we describe the fabrication

  5. Simultaneous spectrophotometric determination of mefenamic acid and paracetamol in a pharmaceutical preparation using ratio spectra derivative spectrophotometry and chemometric methods

    Microsoft Academic Search

    Erdal Dinç; Cem Yücesoy; Feyyaz Onur

    2002-01-01

    Four new methods are described for the simultaneous determination of mefenamic acid (MEF) and paracetamol (PAR) in their combination. In the first method, ratio spectra derivative method, analytical signals were measured at the wavelengths corresponding to either maximums or minimums for both drugs in the first derivative spectra of the ratio spectra obtained by dividing the standard spectrum of one

  6. Polymerization Evaluation by Spectrophotometric Measurements.

    ERIC Educational Resources Information Center

    Dunach, Jaume

    1985-01-01

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

  7. Spectrophotometric methods for the determination of benazepril hydrochloride in its single and multi-component dosage forms.

    PubMed

    El-Yazbi, F A; Abdine, H H; Shaalan, R A

    1999-06-01

    Three sensitive and accurate methods are presented for the determination of benazepril in its dosage forms. The first method uses derivative spectrophotometry to resolve the interference due to formulation matrix. The second method depends on the color formed by the reaction of the drug with bromocresol green (BCG). The third one utilizes the reaction of benazepril, after alkaline hydrolysis, with 3-methylbenzothialozone (MBTH) hydrazone where the produced color is measured at 593 nm. The latter method was extended to develop a stability-indicating method for this drug. Moreover, the derivative method was applied for the determination of benazepril in its combination with hydrochlorothiazide. The proposed methods were applied for the analysis of benazepril in the pure form and in tablets. The coefficient of variation was less than 2%. PMID:10704041

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

    PubMed Central

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

    2013-01-01

    Context: Citicoline (CN) and piracetam (PM) combination in tablet formulation is newly introduced in market. It is necessary to develop suitable quality control methods for rapid and accurate determination of these drugs. Aim: The study aimed to develop the methods for simultaneous determination of CN and PM in combined dosage form. Materials and Methods: The first method was developed by formation and solving simultaneous equations using 280.3 and 264.1 nm as two analytical wavelengths. Second method was absorbance ratio in which wavelengths selected were 256.6 nm as its absorptive point and 280.3 nm as ?max of CN. According to International Conference on Harmonization (ICH) norm, the parameters – linearity, precision, and accuracy were studied. The methods were validated statistically and by recovery studies. Results: Both the drugs obeyed Beer-Lambert's law at the selected wavelengths in concentration range of 5-13 ?g/ml for CN and 10-22 ?g/ml for PM. The percentage of CN and PM in marketed tablet formulation was found to be 99.006 ± 0.173 and 99.257 ± 0.613, respectively; by simultaneous equation method. For Q-Absorption ratio method the percentage of CN and PM was found to be 99.078 ± 0.158 and 99.708 ± 0.838, respectively. Conclusions: The proposed methods were simple, reproducible, precise and robust. The methods can be successfully applied for routine analysis of tablets. PMID:24082696

  9. HPLC-UV method for the quantitation of nevirapine in biological matrices following solid phase extraction

    Microsoft Academic Search

    Joseph W Pav; Lois S Rowland; Deborah J Korpalski

    1999-01-01

    Nevirapine (VIRAMUNE®) is a non-nucleoside reverse transcriptase inhibitor with activity against human immunodeficiency virus type 1 (HIV-1), currently marketed for the treatment of HIV-1 infected adults. A reverse phase HPLC-UV method was optimized and validated for the determination of nevirapine in human plasma, serum, milk and cerebrospinal fluid. The analyte was extracted from 250 ?l of biofluid using a bonded

  10. A SIMPLE HPLC-UV METHOD DEVELOPMENT AND VALIDATION FOR THE QUANTIFICATION OF DEXIBUPROFEN APPLIED IN BIOEQUIVALENCE STUDY

    Microsoft Academic Search

    Punnamchand Loya; Madhusudan N. Saraf

    2012-01-01

    A simple, rapid and sensitive HPLC with UV detection was developed and validated for the determination of dexibuprofen in human plasma. The method involves extracting dexibuprofen with acetonitrile. Chromatographic separation was carried out on a C18 column using mixture of acetonitrile : methanol : potassium dihydrogen phosphate as mobile phase with UV detection at 222 nm. The retention time of dexibuprofen

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

    Microsoft Academic Search

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

    1950-01-01

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

  12. Spectrophotometric determination of labetalol in pharmaceutical preparations and spiked human urine

    Microsoft Academic Search

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

    2003-01-01

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

  13. Number of Nanoparticles per Cell through a Spectrophotometric Method - A key parameter to Assess Nanoparticle-based Cellular Assays

    PubMed Central

    Unciti-Broceta, Juan D.; Cano-Cortés, Victoria; Altea-Manzano, Patricia; Pernagallo, Salvatore; Díaz-Mochón, Juan J.; Sánchez-Martín, Rosario M.

    2015-01-01

    Engineered nanoparticles (eNPs) for biological and biomedical applications are produced from functionalised nanoparticles (NPs) after undergoing multiple handling steps, giving rise to an inevitable loss of NPs. Herein we present a practical method to quantify nanoparticles (NPs) number per volume in an aqueous suspension using standard spectrophotometers and minute amounts of the suspensions (up to 1??L). This method allows, for the first time, to analyse cellular uptake by reporting NPs number added per cell, as opposed to current methods which are related to solid content (w/V) of NPs. In analogy to the parameter used in viral infective assays (multiplicity of infection), we propose to name this novel parameter as multiplicity of nanofection. PMID:25976173

  14. Simultaneous spectrophotometric determination of mefenamic acid and paracetamol in a pharmaceutical preparation using ratio spectra derivative spectrophotometry and chemometric methods.

    PubMed

    Dinç, Erdal; Yücesoy, Cem; Onur, Feyyaz

    2002-06-15

    Four new methods are described for the simultaneous determination of mefenamic acid (MEF) and paracetamol (PAR) in their combination. In the first method, ratio spectra derivative method, analytical signals were measured at the wavelengths corresponding to either maximums or minimums for both drugs in the first derivative spectra of the ratio spectra obtained by dividing the standard spectrum of one of two drugs in 0.1 M NaOH:methanol (1:9). In the chemometric techniques, classical least-squares, inverse least-squares and principal component regression (PCR), the training was randomly prepared by using the different mixture compositions containing two drugs in 0.1 M NaOH:methanol (1:9). The absorbance data was obtained by the measurements at 13 points in the wavelength range 235-355 nm in the absorption spectra. Chemometric calibrations were constructed by the absorbance data and training set for the prediction of the amount of MEF and PAR in samples. In the third chemometric method, PCR, the covariance matrix corresponding to the absorbance data was calculated for the basis vectors and matrix containing the new coordinates. The obtained calibration was used to determine the title drugs in their mixture. Linearity range in all the methods was found to be 2-10 microg/ml of MEF and 4-20 microg/ml of PAR. Mean recoveries were found satisfactory (>99%). The procedures do not require any separation step. These methods were successfully applied to a pharmaceutical formulation, tablet, and the results were compared with each other. PMID:12049974

  15. A vacuum ultraviolet spectrophotometric system

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

    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.

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

    PubMed

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

    2014-12-15

    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 60 min 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 13.5 min 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

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

    PubMed

    Ertürk, Sidika; Cetin, Sevil Müge; Atmaca, Sedef

    2003-10-15

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

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

    Microsoft Academic Search

    Mustafa Özyürek; Kubilay Güçlü; Burcu Bekta?o?lu; Re?at Apak

    2007-01-01

    The proposed method for ascorbic acid: AA (Vitamin C) determination is based on the oxidation of AA to dehydroascorbic acid with the CUPRAC reagent of total antioxidant capacity assay, i.e., Cu(II)-neocuproine (Nc), in ammonium acetate-containing medium at pH 7, where the absorbance of the formed bis(Nc)-copper(I) chelate is measured at 450nm. The flavonoids (essentially flavones and flavonols) normally interfering with

  19. Application of principal component-artificial neural network models for simultaneous determination of phenolic compounds by a kinetic spectrophotometric method.

    PubMed

    Hasani, Masoumeh; Moloudi, Mahsa

    2008-08-30

    A multicomponent analysis method based on principal component analysis-artificial neural network models (PC-ANN) is proposed for the determination of phenolic compounds. The method relies on the oxidative coupling of phenols (phenol, 2 chlorophenol, 3-chlorophenol and 4-chlorophenol) to N,N-diethyl-p-phenylenediamine in the presence of hexacyanoferrate(III). The reaction monitored at analytical wavelength 680 nm of the dye formed. Phenols can be determined individually over the concentration range 0.1-7.0 microg ml(-1). Differences in the kinetic behavior of the four species were exploited by using PC-ANN, to resolve mixtures of phenol. After reducing the number of kinetic data using principal component analysis, an artificial neural network consisting of three layers of nodes was trained by applying a back-propagation learning rule. The optimized ANN allows the simultaneous quantitation of four analytes in mixtures with relative standard errors of prediction in the region of 5% for four species. The results show that PC-ANN is an efficient method for prediction of the four analytes. PMID:18272286

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

    PubMed

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

    2001-10-01

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

  1. Quantification of protein concentration using UV absorbance and Coomassie dyes.

    PubMed

    Noble, James E

    2014-01-01

    The measurement of a solubilized protein concentration in solution is an important assay in biochemistry research and development labs for applications ranging from enzymatic studies to providing data for biopharmaceutical lot release. Spectrophotometric protein quantification assays are methods that use UV and visible spectroscopy to rapidly determine the concentration of protein, relative to a standard, or using an assigned extinction coefficient. Where multiple samples need measurement, and/or the sample volume and concentration is limited, preparations of the Coomassie dye commonly known as the Bradford assay can be used. PMID:24423263

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

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

    PubMed

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

    2013-03-30

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

  4. Determination of protolytic equilibria for methyl 3-azido-6-iodo-2,3,6-trideoxy-?- D- arabino-hexopyranoside by ab initio and spectrophotometric methods

    NASA Astrophysics Data System (ADS)

    D?browska, Aleksandra; Makowski, Mariusz; Jacewicz, Dagmara; Chylewska, Agnieszka; Chmurzy?ski, Lech

    2008-12-01

    UV absorption spectra of methyl 3-azido-6-iodo-2,3,6-trideoxy-?- D- arabino-hexopyranoside were recorded over a wide pH range. On this basis, a relationship between absorbance and pH was plotted, from which deprotonation equilibrium constants of this compound were determined. Further, quantum-mechanical calculations were performed at the ab initio level both in the gas phase by using the Restricted Hartree Fock (RHF), Møller-Plesset (MP2) methods and under consideration of solvation effects within the Polarizable Continuum Model (PCM), which enabled location of preferred protonation and deprotonation centers of this compound. The results provided the basis for discussion of the influence of substituents in the sugar ring on protolytic equilibria occurring in aqueous solutions of 3-azido-2,3-dideoxy sugars.

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

    NASA Astrophysics Data System (ADS)

    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

    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.

  6. The Rigorous Evaluation of Spectrophotometric Data to Obtain an Equilibrium Constant.

    ERIC Educational Resources Information Center

    Long, John R.; Drago, Russell S.

    1982-01-01

    Most students do not know how to determine the equilibrium constant and estimate the error in it from spectrophotometric data that contain experimental errors. This "dry-lab" experiment describes a method that may be used to determine the "best-fit" value of the 1:1 equilibrium constant to spectrophotometric data. (Author/JN)

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

    PubMed Central

    Saini, Balraj; Bansal, Gulshan

    2014-01-01

    Sulfasalazine (SSZ) was subjected to degradation under the conditions of hydrolysis (acid, alkali, and water), oxidation (30% H2O2), dry heat, and photolysis (UV-VIS light) in accordance with the ICH guidelines. An RP-HPLC method was developed to study the degradation behavior. No degradation was noted under any condition except alkaline hydrolysis where SSZ was degraded to a single minor product. SSZ was optimally resolved from this product on an XTerra® RP18 column with a mobile phase composed of methanol and an ammonium acetate buffer (10 mM, pH 7.0) (48:52, v/v) delivered at a rate of 0.8 mL/min in an isocratic mode. The method was validated and found to be linear (r2=0.99945), precise (%RSD <2), robust, and accurate (94–102%) in the concentration range of 0.5–50 ?g/mL of SSZ. The PDA analysis of the degraded sample revealed the SSZ peak purity to be 998.99 and the drug peak eluted with a resolution factor of >2 from the nearest resolving peak, indicating the method to be selectively stability-indicating for the drug analysis. The method was applied successfully for the stability testing of the commercially available SSZ tablets that were under varied ICH-prescribed conditions. An explanation for the unusual stability of the drug when exposed to acidic hydrolysis, despite the presence of the sulfonamide linkage, is also discussed. PMID:24959403

  8. 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

    S. Balasubramanian; V. Pugalenthi

    1999-01-01

    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

  9. 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)

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

    2005-01-01

    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.

  10. [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

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

    2013-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2003-04-01

    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.

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

    PubMed Central

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

    2013-01-01

    An ultra-fast liquid chromatographic method and two UV spectroscopic methods were developed for the determination of cephalexin monohydrate in pharmaceutical dosage forms. Isocratic separation was performed on an Enable C18G column (250 mm × 4.6 mm i.d., 5 ?m) using methanol:0.01 M TBAHS (50:50, v/v) as the mobile phase at a flow rate of 1.0 ml/min. The PDA detection wavelength was set at 254 nm. The UV spectroscopic method was performed at 261 nm and at 256–266 nm for the AUC method using a phosphate buffer (pH=5.5). The linearity was observed over a concentration range of 1.0–120 ?g/ml for UFLC and both of the UV spectroscopic methods (correlation coefficient=0.999). The developed methods were validated according to ICH guidelines. The relative standard deviation values for the intraday and interday precision studies were < 2%, and the accuracy was > 99% for all of the three methods. The developed methods were used successfully for the determination of cephalexin in dry syrup formulation. PMID:24482771

  13. Estimation of scattering error in spectrophotometric measurements of light absorption

    E-print Network

    Stramski, Dariusz

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

  14. Blue CrO5 assay: a novel spectrophotometric method for the evaluation of the antioxidant and oxidant capacity of various biological substances.

    PubMed

    Charalampidis, Pavlos S; Veltsistas, Panos; Karkabounas, Spyros; Evangelou, Angelos

    2009-10-01

    Oxidative stress plays a pivotal role in the ageing process and in the pathogenesis of numerable diseases. The quantification of the phenomenon is of paramount importance. In the present study, we introduce a novel and simple assay, the Blue CrO(5) assay, for the evaluation of the oxidant and antioxidant capacity of various biological samples and known antioxidants. Chromium peroxide (CrO(5)) is produced by ammonium dichromate in an acidic environment in the presence of H(2)O(2). It is a deep blue potent oxidant compound, miscible and relatively stable in polar organic solvents, that can be easily measured by spectrophotometry. Its reduction by known antioxidants, both water- and lipid-soluble (ascorbate and alpha-tocopherol, respectively, in this study), detected spectrophotometrically as a decrease in the absorption and depicted in EPR spectra, can act as a measure of the antioxidant capacity of a certain compound. The assay displays significant sensitivity, stability, linearity, specificity and repeatability. PMID:19527917

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

    SciTech Connect

    Badosa, Jordi; Calbo, J.; McKenzie, R. L.; Liley, Ben; Gonzalez, J. A.; Forgan, B. W.; Long, Charles N.

    2014-07-01

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

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

    NASA Technical Reports Server (NTRS)

    Mitchell, B. Greg

    2000-01-01

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

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

    PubMed Central

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

    2008-01-01

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

  18. Stress degradation studies on Telmisartan and development of a validated method by UV spectrophotometry in bulk and pharmaceutical dosage forms

    PubMed Central

    Patel, Komal; Dhudasia, Komal; Patel, Amit; Dave, Jayant; Patel, Chaganbhai

    2011-01-01

    Aim and Background: To develop and validate a simple, precise, accurate, and stability indicating a UV-method for estimation of Telmisartan (TELM). UV, HPLC, HPTLC, and many more experiments were carried out by taking single drug and also by combining with other drugs. However, Such type of studies was not reported. Materials and Methods: In both methods, TELM has the absorbance maxima at 296 nm. Method A involves method development and validation and Method B involves forced degradation study. In these methods, methanol was used as a solvent. Linearity was observed in the concentration range of 4–16 ?g/ml. Validation experiments were performed to demonstrate system suitability, specificity, precision, linearity, accuracy, robustness, LOD, and LOQ as per International Conference on Harmonization guidelines. Furthermore stability studies of TELM were carried out under acidic, alkali, neutral, oxidation, photolytic, and thermal degradation as per stability indicating assay methods. Results: The results of analysis have been validated, and recovery studies were carried out using a standard addition method by adding specific drug amount (80%, 100%, and 120%) and show recovery studies in the range (99.26–101.26)%. Conclusion: The proposed method can be successfully applied for method development, validation, and stability study of TELM. PMID:23781466

  19. A Simple Sample Preparation with HPLC-UV Method for Estimation of Clomipramine from Plasma

    PubMed Central

    Mostafavi, Sayed Abolfazl; Tahvilian, Reza; Dehghani Poudeh, Masoumeh; Rafeepour, Zeinab

    2010-01-01

    Clomipramine is a tricyclic antidepressant. Different methods for determination of clomipramine hydrochloride in plasma have been described. Most of these procedures favor the use of acidic back-extraction in extraction procedure and HPLC as the analytical technique. In this study, the clomipramine extraction procedure was modified and a direct injection to the column was performed to shorten the time of sample preparation considerably. Furthermore, the method was applied in bioequivalence study of new formulations of clomipramine in comparison with reference tablets. The drug and internal standard were extracted from plasma with heptan : isoamyl alcohol (95:5) and re-extracted with 200 ?L of orthophosphoric acid (0.3% v/v). The organic layer was discharged and analysis was performed on C8 reverse phase ODS2 HPLC column with a mobile phase, acetonitrile : water (75:25) and UV detection set at 215 nm. Additionally, a single dose study was carried out with a two-sequence, crossover block-randomized design for bioequivalence study. Clomipramine tablets (3 × 25 mg) of either formulations (reference or test products) were administered separately in two occasions to 12 fasting healthy male volunteers. Blood samples were taken prior to and at 9 points within 48 h after dose administration. The retention time of internal standard (cisapride), clomipramine, and desmethyl clomipramine were 5.6 ± 0.2, 10.3 ± 0.3, and 9.5 ± 0.3 min, respectively. The standard curve covering the concentration ranges of 2.5-120 ng/mL was linear (r2 = 0.9950 and 0.9979) for clomipramine and desmethyl clomipramine. The co-efficient of variation for intra-day and inter-day accuracy and precision was less than 18.3%. The pharmacokinetic parameters Cmax and Tmax were obtained directly from plasma clomipramine concentrations. Kel was estimated by log-linear regression and AUC was calculated by the linear trapezoidal rule. The pharmacokinetic parameters AUC and Cmax were tested for equivalence after log-transformation of data. The 90% standard confidence intervals of the mean values for the test/reference ratios, AUC, and Cmax were within the acceptable bioequivalence limits of 0.80-1.20. These results indicated that the analytical method was linear and accurate. Test and reference formulations were found to be bioequivalent and therefore interchangeable. PMID:24363733

  20. Searching for triatomines. A new method for field search using UV light

    Microsoft Academic Search

    Silvia Catalá

    2010-01-01

    Detection of triatomine bugs within a house is essential for the estimation of Chagas disease transmission risk and for evaluating the success of insecticidal control attempts. Small residual populations could represent an important risk but are difficult to detect by time manual sampling. Faecal marks from triatomines are clearly detectable with an ultraviolet (UV) light on most of the materials

  1. UV-visible spectroscopy method for screening the chemical stability of potential antioxidants for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Banham, Dustin; Ye, Siyu; Knights, Shanna; Stewart, S. Michael; Wilson, Mahlon; Garzon, Fernando

    2015-05-01

    A novel method based on UV-visible spectroscopy is reported for screening the chemical stability of potential antioxidant additives for proton exchange membrane fuel cells, and the chemical stabilities of three CeOx samples of varying crystallite sizes (6, 13, or 25 nm) are examined. The chemical stabilities predicted by this new screening method are compared to in-situ membrane electrode assembly (MEA) accelerated stress testing, with the results confirming that this rapid and inexpensive method can be used to accurately predict performance impacts of antioxidants.

  2. Separation and spectrophotometric determination of elements

    SciTech Connect

    Marczenko, Z.

    1986-01-01

    The book provides much information on the aqueous chemistry and isolation of the elements and could prove to be a useful resource for sample preparation. The sections on metal isolation methods are particularly interesting. The depth of citation is impressive. Spectrophotometric enthusiasts will enjoy the book. Individuals concerned with the chromatographic separation of elements (a subject totally neglected in the volume) will find an interesting compilation of chemistry that could be useful to them. Atomic spectroscopists may find it useful in deriving preconcentration methods. Chemical analysts will find the book of marginal utility. Anyone using the book will have to supply their own analysis of the quality of most procedures, the details of which require consulting the cited references.

  3. The effect of different propolis harvest methods on its lead contents determined by ET AAS and UV-visS.

    PubMed

    Sales, A; Alvarez, A; Areal, M Rodriguez; Maldonado, L; Marchisio, P; Rodríguez, M; Bedascarrasbure, E

    2006-10-11

    Argentinean propolis is exported to different countries, specially Japan. The market demands propolis quality control according to international standards. The analytical determination of some metals, as lead in food, is very important for their high toxicity even in low concentrations and because of their harmful effects on health. Flavonoids, the main bioactive compounds of propolis, tend to chelate metals as lead, which becomes one of the main polluting agents of propolis. The lead found in propolis may come from the atmosphere or it may be incorporated in the harvest, extraction and processing methods. The aim of this work is to evaluate lead level on Argentinean propolis determined by electrothermal atomic absorption spectrometry (ET AAS) and UV-vis spectrophotometry (UV-visS) methods, as well as the effect of harvest methods on those contents. A randomized test with three different treatments of collection was made to evaluate the effect of harvest methods. These procedures were: separating wedges (traditional), netting plastic meshes and stamping out plastic meshes. By means of the analysis of variance technique for multiple comparisons (ANOVA) it was possible to conclude that there are significant differences between scraped and mesh methods (stamped out and mosquito netting meshes). The results obtained in the present test would allow us to conclude that mesh methods are more advisable than scraped ones in order to obtain innocuous and safe propolis with minor lead contents. A statistical comparison of lead determination by both, ET AAS and UV-visS methods, demonstrated that there is not a significant difference in the results achieved with the two analytical techniques employed. PMID:16787698

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

    PubMed

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

    2008-09-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

    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.

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

    Microsoft Academic Search

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

    2010-01-01

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

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

    PubMed

    Pires-Oliveira, Rafael; Joekes, Inés

    2014-11-01

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

  9. Design for CD correction strategy using a resist shrink method via UV irradiation for defect-free photomask

    NASA Astrophysics Data System (ADS)

    Ryu, Jin Ho; Lee, Dong Wook; Jung, Ho Yong; Kim, Sang Pyo; Han, Oscar

    2007-10-01

    As the specification for photomask becomes tighter, it is strongly demanded for achieving precise CD MTT (critical dimension mean to target) and enhanced defect controllability in photomask fabrication. First of all, it is necessary that reducing the factors of CD MTT error and introducing the reliable method to correct CD error for accurate CD requirement of attenuated PSM (phase shift mask). From this point of view, one of CD correction methods which consist of Cr CD measurement step after resist strip (strip inspection CD: SI CD) and additional corrective Cr dry etch step was developed. Previous SI CD correction process resulted in accurate CD control within the range of CD MTT. However it was not appropriate for defect control due to additional resist processes for selective protection of Cr pattern during CD correction process. In this study, the method for achieving precise CD MTT by correcting CD error without any resist process is investigated. It is not suitable for the CD correction process to control CD MTT precisely that Cr etched resist (etch inspection CD: EI CD) is very vulnerable to E-beam scanning during CD measurement. Otherwise, photoresist after Cr etch selectively shrinks via UV irradiation under ozone (O3) condition, which drives a reduction of CD MTT error as a result of accurate CD measurement (UV-irradiation inspection CD: UI CD). Moreover, it is not necessary any resist process for Cr protection due to UV irradiated resist as enough for a etch barrier. It is a strong advantage of novel CD correction method. This strategy solves the problems such as both CD measurement error on the EI CD correction method and defects originated from resist process on the SI CD correction method at once. For the successful incorporation of UI CD correction method, several items related with CD should be evaluated: accuracy and repeatability of CD measurement under UI CD, control of CD MTT and CD uniformity, additional corrective etch bias for UI CD, independence of corrective Cr etch process from UV irradiated resist, isolated-dense CD difference,.. etc. In this paper, strategy of design for the progressive CD correction method for defect-free photomask and process details will be discussed.

  10. Spectrophotometric determination of etodolac in pure form and pharmaceutical formulations

    Microsoft Academic Search

    Ayman A Gouda; Wafaa S Hassan

    2008-01-01

    BACKGROUND: Etodolac (ETD) is a non-steroidal anti-inflamatory antirheumatic drug. A survey of the literature reveals that there is no method available for the determination of ETD in pure form and pharmaceutical formulations by oxidation-reduction reactions. RESULTS: We describe three simple, sensitive and reproducible spectrophotometric assays (A-C) for the determination of etodolac in pure form and in pharmaceutical formulations. Methods A

  11. New developments for the numerical analysis of spectrophotometric titrations

    Microsoft Academic Search

    Raylene M. Dyson; Porn Jandanklang; Marcel Maeder; Caroline J. Mason; Andrew Whitson

    1999-01-01

    Spectrophotometric titrations are a valuable tool for the investigation of solution equilibria. Data acquisition and recent developments on methods for the analysis of the measurements are discussed in this contribution. Hard-modeling methods are based on non-linear least-squares fitting, and algorithms have been developed which can cope with the large amount of data and parameters of multiwavelength or multivariate measurements. Good

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

    PubMed Central

    Singh, Jaswant; Singh, Rudra P.

    2014-01-01

    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

  13. Application of chrome azurol S for the extractive spectrophotometric determination of fluoxetine and fluvoxamine.

    PubMed

    Starczewska, B; Mielech, K

    2000-08-15

    Chrome azurol S has been tested as a spectrophotometric reagent for the determination of fluoxetine (FXT) and fluvoxamine (FXM). It reacts in aqueous media with FXT and FXM forming coloured, sparingly soluble in water compounds. These compounds can be quantitatively extracted with some organic solvents. This property has been exploited for the development of the extractive spectrophotometric methods for the determination of fluoxetine and fluvoxamine. PMID:10933516

  14. A recursive method to calculate UV-divergent parts at one-loop level in dimensional regularization

    NASA Astrophysics Data System (ADS)

    Feng, Feng

    2012-07-01

    A method is introduced to calculate the UV-divergent parts at one-loop level in dimensional regularization. The method is based on the recursion, and the basic integrals are just the scaleless integrals after the recursive reduction, which involve no other momentum scales except the loop momentum itself. The method can be easily implemented in any symbolic computer language, and a implementation in MATHEMATICA is ready to use. Catalogue identifier: AELY_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AELY_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 26 361 No. of bytes in distributed program, including test data, etc.: 412 084 Distribution format: tar.gz Programming language: Mathematica Computer: Any computer where the Mathematica is running. Operating system: Any capable of running Mathematica. Classification: 11.1 External routines: FeynCalc (http://www.feyncalc.org/), FeynArts (http://www.feynarts.de/) Nature of problem: To get the UV-divergent part of any one-loop expression. Solution method: UVPart is a Mathematica package where the recursive method has been implemented. Running time: In general it is below one second.

  15. [Research on structure and UV curing behaviors of novel cardanol-based unsaturated resins using FTIR spectrum analysis method].

    PubMed

    Li, Shou-Hai; Yang, Xue-Juan; Li, Mei; Huang, Kun; Xia, Jian-Ling

    2013-10-01

    Two dissimilar cardanol-based unsaturated resin monomers were prepared via simple ring-opening and etherification reaction by utilizing the reactivity between phenolic hydroxyl and epoxy group with the aid of cardanol as raw material. The transformations of different groups were characterized using Fourier transform infrared (FTIR) during the synthesis process, the resin monomers' structure was further analyzed using the 1H-nuclear magnetic resonance (1H-NMR) and gel permeation chromatography (GPC), and the UV curing behaviors of resin monomers were studied by means of FTIR method. In addition, the thermal stability of UV cured resin monomers were also tested by thermogravimetric analysis (TGA). The molecular structure analysis demonstrated that these two target products were successfully synthesized. UV curing behaviors analysis showed that the prepared cardanol-based unsaturated resin monomers could reach ultimate curing level within 30 s. TGA results showed that the molecular structure and the content of double bond had critical influence on their thermal stability. The main initial thermal decomposition temperature of these two cured resin monomers was all above 350 degrees C. PMID:24409711

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

    NASA Astrophysics Data System (ADS)

    Shabannia, R.; Hassan, H. Abu

    2014-07-01

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

  17. A reversed-phase HPLC-UV method developed and validated for simultaneous quantification of six alkaloids from Nicotiana spp.

    PubMed

    Moghbel, Nahid; Ryu, BoMi; Steadman, Kathryn J

    2015-08-01

    A reversed-phase HPLC-UV method was developed, optimized, and validated for the separation and quantitation of six target alkaloids from leaves of Nicotiana species (nicotine, nornicotine, anatabine, anabasine, myosmine, and cotinine). A bidentate reversed-phase C18 column was used as stationary phase and an alkaline ammonium formate buffer and acetonitrile as mobile phase. The alkaloids were well separated in a short run time of 13min with mobile phase pH 10.5 and a small gradient of 9-13% acetonitrile, and detected using UV at 260nm. Peak parameters were acceptable for all six closely related alkaloids. The proposed method has enough linearity with correlation coefficient >0.999 within the investigated range for all tested alkaloids. Satisfactory precision was achieved for both intra- and inter-day assay, with RSD less than 2% for all alkaloid standards. Reproducibility was also within the acceptable range of RSD <2%. Limit of detection was 1.6?g/mL for nicotine and below 1?g/mL for all other alkaloids. The limit of quantification was 2.8 and 4.8?g/mL for nornicotine and nicotine respectively, and below 2?g/mL for all other alkaloids. The method was successfully applied for simultaneous analysis of alkaloids in leaves of Nicotiana benthamiana. PMID:26114650

  18. Comparison of multivariate calibration methods to determine simultaneously mebendazole-cambendazole and mebendazole-thiabendazole in pharmaceutical preparations by UV-visible spectrophotometry.

    PubMed

    Andrade, Suely R C; Scarminio, Ieda S; Nery, Marlene M F; de Oliveira, Aline C

    2003-11-24

    Three multivariate calibration methods, Principal Component Regression (PCR), the K-matrix method and Q-mode factor analysis followed by varimax and Imbrie's oblique rotations were applied to the simultaneous spectrophotometric determinations of mebendazole (MBZ)-cambendazole (CBZ) and thiabendazole (TBZ)-mebendazole in commercial samples of Exelmin and Helmiben. The calibration set concentrations were selected to contain a +/-10% variation in the quantity of active ingredients as declared by the manufacturer. The Q-mode factor analysis provides superior results for the two pharmaceutical formulations. The K-matrix method proved to be totally inadequate for these determinations. Almost all Q-mode results have relative errors much smaller than 5% of the active ingredient contents. This investigation shows that PCR and Q-mode factor analysis can be used to determine MBZ-CBZ and TBZ-MBZ in commercial drugs. PMID:14623591

  19. New 1,2,4-triazole-based azo-azomethine dye. Part III: Synthesis, characterization, thermal property, spectrophotometric and computational studies

    NASA Astrophysics Data System (ADS)

    Erfantalab, Malihe; Khanmohammadi, Hamid

    A new 1,2,4-triazole-based azo-azomethine compound, H2L, has been prepared by condensation reaction of 1-(3-formyl-4-hydroxyphenylazo)-4-ethylbenzene with prepared triazole-based diamine. The structure of H2L was characterized by using FT-IR, UV-Vis and 1H NMR spectroscopic methods as well as elemental analysis. Hard model chemometrics method has been used to determine the formation constants of zinc(II), copper(II), nickel(II) and cobalt(II) complexes of H2L in DMSO by UV-Vis spectrophotometric method. Solvatochromic behavior of the dye has been also investigated in some organic solvents with different polarities. Thermal properties of the prepared dye was examined by thermogravimetric analysis. Results indicated that the framework of the dye was stable up to 245 °C. Furthermore,1H chemical shifts and UV-Vis of H2L were studied by the gauge independent atomic orbital (GIAO), continuous set of gauge transformations (CSGT) and time-dependent density functional theory (TD-DFT) methods respectively at the level of density functional theory using B3LYP/6-311+G(d) basis sets in DMSO. The computational data are in reasonably good agreement with the experimental data.

  20. MOF crystal growth: UV resonance Raman investigation of metal-ligand binding in solution and accelerated crystal growth methods.

    PubMed

    Petersen, Thomas D; Balakrishnan, Gurusamy; Weeks, Colin L

    2015-07-01

    Determining the mechanism of metal-organic framework (MOF) crystal growth is important for the development of more efficient and reliable synthetic methods. Resonance Raman spectroscopy has been used for the first time to detect interactions in solution between metal ions and bridging ligands as MOFs form. UV excitation (229 nm) produced strong resonance enhancement of 4,4'-bipyridine (bpy) vibrational bands and showed that soluble Co(2+)-bpy species formed in solution prior to the growth of MOF crystals from bpy and Co(NO3)2. The results of the Raman experiments informed the development of faster methods for synthesizing [Co2(bpy)3(NO3)4]n 2D bilayer and [Co(bpy)(NO3)2(H2O)2]n 1D chain MOFs. PMID:26100962

  1. Simultaneous determination of toltrazuril and its metabolites in chicken and pig skin+fat by UPLC-UV method.

    PubMed

    Zheng, Wenli; Jiang, Zhaoling; Zhang, Lifang; Zhang, Chong; Zhang, Xiao; Fei, Chenzhong; Zhang, Keyu; Wang, Xiaoyang; Wang, Mi; Li, Tao; Xiao, Sui; Wang, Chunmei; Xue, Feiqun

    2014-12-01

    A reliable method for the simultaneous determination of toltrazuril and its main metabolites (toltrazuril sulphone and toltrazuril sulphoxide) in chicken and pig skin+fat was developed and validated. Analytes were extracted from skin+fat with acetonitrile. The crude extracts were subjected to liquid-liquid extraction with n-hexane, and then further cleaned using primary secondary amine and Oasis™ MAX solid phase extraction cartridges. Chromatographic separation by UPLC-UV was performed on a C18+ reversed-phase column with gradient elution. Relative recovery from the spiked samples ranged from 84.8% to 109.1%. Limits of detection and quantification for the analytes were within 25-37.5?gkg(-1) and 50-75?gkg(-1), respectively. The developed method has been successfully applied to the depletion study of toltrazuril drug residues in chicken skin+fat. The recommended withdrawal period with oral administration based on our research is 24.18 days. PMID:25444542

  2. Ultraviolet spectrophotometric determination of tantalum with pyrogallol

    USGS Publications Warehouse

    Dinnin, J.I.

    1953-01-01

    In a search for a more rapid method for the determination of tantalum in rocks and minerals, an intensive study was made of the tantalum-pyrogallol reaction recommended by Platanov and Krivoshlikov, and a better modified spectrophotometric procedure is given. The improved method consists in measuring the absorbancy of the tantalum-pyrogallol complex at 325 m?? in 4N hydrochloric acid and a fixed concentration (0.0175M) of ammonium oxalate. Beer's law is followed for the concentration range up to 40 ?? per ml. Sensitivity in terms of molar absorbancy index is 4775. Most interferences are additive in character and readily correctable. Separations or major corrections are required in the presence of significant amounts of molybdenum, tungsten, antimony, and uranium. The method has been successfully applied to three ores previously analyzed by gravimetric techniques. The method affords greater speed, sensitivity, and reproducibility in the determination of tantalum in rocks and minerals. A more reliable technique for preparing standard solutions of tantalum has been developed.

  3. Spectrophotometric estimation of individual flavone glycosides in three Euphorbia species.

    PubMed

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

    1975-06-01

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

  4. HPLC-UV method for nicotine, strychnine, and aconitine in dairy products.

    PubMed

    Jablonski, Joseph E; Schlesser, Joseph E; Mariappagoudar, Purnima

    2006-10-01

    The toxic nitrogen alkaloids nicotine, strychnine, and aconitine were quantitated in whole milk, skim milk, and cream using solid-phase extraction cleanup and HPLC-UV with dual wavelength detection. Samples were extracted in McIlvaine's buffer with EDTA and then partitioned with aqueous acetonitrile and hexane. The aqueous phase was concentrated and passed through an OASIS HLB column. The column was eluted with methylene chloride/ammonium hydroxide, 1 mL/1 microL, v/v. The eluent was acidified with hydrochloric acid and evaporated. The sample was diluted for HPLC with acetonitrile/phosphate buffer pH 7.4. Chromatography was performed on an Xterra RP-18 column using a gradient of acetonitrile and ammonium bicarbonate buffer at pH 9.8. Nicotine and strychnine were monitored at 260 nm; aconitine was monitored at 232 nm. Calibration curves were generated from external standards in the range 0.2-10 microg/mL using 1/x weighting. Mean recoveries in whole milk spiked between 0.1 and 10 ppm were the following: nicotine 89.2%, strychnine 75.7%, and aconitine 85.1%. Mean recoveries in skim milk spiked between 0.1 and 10 ppm were the following: nicotine 72.1%, strychnine 78.2%, and aconitine 82.9%. Mean recoveries in cream spiked between 0.2 and 20 ppm were the following: nicotine 87.9%, strychnine 76.9%, and aconitine 82.0%. Relative standard deviations of recovery were less than 20% in each case. PMID:17002408

  5. Amperometric enzyme sensor to check the total antioxidant capacity of several mixed berries. Comparison with two other spectrophotometric and fluorimetric methods.

    PubMed

    Tomassetti, Mauro; Serone, Maruschka; Angeloni, Riccardo; Campanella, Luigi; Mazzone, Elisa

    2015-01-01

    The aim of this research was to test the correctness of response of a superoxide dismutase amperometric biosensor used for the purpose of measuring and ranking the total antioxidant capacity of several systematically analysed mixed berries. Several methods are described in the literature for determining antioxidant capacity, each culminating in the construction of an antioxidant capacity scale and each using its own unit of measurement. It was therefore endeavoured to correlate and compare the results obtained using the present amperometric biosensor method with those resulting from two other different methods for determining the total antioxidant capacity selected from among those more frequently cited in the literature. The purpose was to establish a methodological approach consisting in the simultaneous application of different methods that it would be possible to use to obtain an accurate estimation of the total antioxidant capacity of different mixed berries and the food products containing them. Testing was therefore extended to also cover jams, yoghurts and juices containing mixed berries. PMID:25654720

  6. Simultaneous spectrophotometric determination of tartrazine, patent blue V, and indigo carmine in commercial products by partial least squares and principal component regression methods

    Microsoft Academic Search

    J. J. Berzas Nevado; J. Rodr??guez Flores; M. J. Villaseñor Llerena; N. Rodr??guez Fariñas

    1999-01-01

    Two multivariate calibration methods, partial least squares (PLS-1) and principal component regression (PCR) were proposed and successfully applied to the simultaneous determination of three dyes, tartrazine (T) (E-102), patent blue V (P) (E-131), and indigo carmine (I) (E-132) in mixtures by ultraviolet-visible absorption spectrophotometry. Calibration models were evaluated by internal validation (prediction of dyes concentration in its own designed training

  7. An ultraviolet spectrophotometric assay for measuring lipase activity using long-chain triacyglycerols from Aleurites fordii seeds.

    PubMed

    Pencreac'h, Gaëlle; Graille, Jean; Pina, Michel; Verger, Robert

    2002-04-01

    In this study, we designed a specific, continuous, and sensitive UV spectrophotometric lipase assay using natural triacylglycerols (TAGs) from the Aleurites fordii seed oil (tung oil). alpha-Eleostearic acid (9,11,13-cis, trans,trans-octadecatrienoic acid) is the main fatty acid component (it accounts for up to 70%) of the TAGs from tung oil. The conjugated triene present in alpha-eleostearic acid constitutes an intrinsic chromophore, which confers strong UV absorption properties on both the free fatty acid and the TAGs from tung oil. The lipase assay is based on the difference between the apparent molar extinction coefficients of the two types of alpha-eleostearic acid present, that which is esterified into TAGs and that which is released into the reaction medium. This difference is responsible for the variations in the UV absorption spectrum of the reaction medium occurring upon enzymatic TAGs hydrolysis. Using the purified lipase from Thermomyces lanuginosa (TLL) and the detergent sodium taurodeoxycholate (NaTDC, 4 mM), it was established that the most suitable method of measuring lipolysis consisted of monitoring the decrease in the OD at 292 nm, which was linear with time and proportional to the amount of lipase added. In order to be able to estimate the specific activity of TLL, we determined an apparent molar extinction coefficient of alpha-eleostearic acid (epsilon = 13,900 M(-1) cm(-1)) under the assay conditions. Amounts of pure TLL as small as 1 ng can be easily detected in the presence of 4 mM NaTDC. Interestingly, the NaTDC concentration can be decreased as far as 0.05 mM. In comparison with other well-known methods of lipase assay, the detection limit of this new method is 100-fold lower than with the pH-stat method and similar to that of a fluorescent assay recently developed at our laboratory. PMID:11906146

  8. Flow injection spectrophotometric determination of methamidophos using online hydrolysis.

    PubMed

    Jan, Mohammad Rasul; Shah, Jasmin; Bashir, Nadia; Salman, M

    2010-08-01

    A new protocol for the online spectrophotometric determination of methamidophos has been developed. The method is based on online hydrolysis of methamidophos, and the resulting hydrolyzed product is reacted with sodium nitroproside to form a colored complex. The calibration curve is linear over the concentration range of 0.5-20 microgml(-1), with a molar absorptivity of 2.5x10(4) L mol(-1) cm(-1). The method is fast and reproducible with a sample throughput of 90 samples/h. The method is successfully applied to formulations and real samples. PMID:19609695

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  12. Spectrophotometric Determination of some Recently Introduced Antibacterial Drugs Using Ferric Chloride

    Microsoft Academic Search

    S. K. Bhowal; T. K. Das

    1991-01-01

    Simple and selective spectrophotometric methods for the determination of norfloxacin, ciprofloxacin, cinoxacin and nalidixic acid are described. The methods are based on the measurement of the intensity of the orange-red colour produced by the drugs with ferric chloride in dimethylsulphoxide-methanol medium. The methods are highly accurate and have been successfully applied for analysis of bulk drugs and pharmaceutical preparations. The

  13. Quality assessment of the saffron samples using second-order spectrophotometric data assisted by three-way chemometric methods via quantitative analysis of synthetic colorants in adulterated saffron.

    PubMed

    Masoum, Saeed; Gholami, Ali; Hemmesi, Marjan; Abbasi, Saleheh

    2015-09-01

    Saffron is a valuable culinary spice that can be used not only for dyes and cooking, but also for many medical purposes. Due to its high price and restriction of its production, various fraud manners in its production have been growing. Addition of synthetic colorants to saffron is the most common way for adulteration. In this work, chemometric methods are proposed to resolve the three-dimensional absorbance spectra-pH data for simultaneous determination of the two colorants Tartrazin and Sunset yellow, in adulterated saffron. The rank deficiency in the concentration mode impaired the system. Therefore, to extirpate the ambiguity, which results from rank deficiency, three-way variation array V was generated by subtracting the first pH spectrum from each spectrum at each pH. This allows the extraction of extent reaction profile and mixture reaction spectral profiles, as well as the relative concentrations of the analytes. PMID:25919327

  14. Quality assessment of the saffron samples using second-order spectrophotometric data assisted by three-way chemometric methods via quantitative analysis of synthetic colorants in adulterated saffron

    NASA Astrophysics Data System (ADS)

    Masoum, Saeed; Gholami, Ali; Hemmesi, Marjan; Abbasi, Saleheh

    2015-09-01

    Saffron is a valuable culinary spice that can be used not only for dyes and cooking, but also for many medical purposes. Due to its high price and restriction of its production, various fraud manners in its production have been growing. Addition of synthetic colorants to saffron is the most common way for adulteration. In this work, chemometric methods are proposed to resolve the three-dimensional absorbance spectra-pH data for simultaneous determination of the two colorants Tartrazin and Sunset yellow, in adulterated saffron. The rank deficiency in the concentration mode impaired the system. Therefore, to extirpate the ambiguity, which results from rank deficiency, three-way variation array V was generated by subtracting the first pH spectrum from each spectrum at each pH. This allows the extraction of extent reaction profile and mixture reaction spectral profiles, as well as the relative concentrations of the analytes.

  15. A new method for the absolute radiance calibration for UV/vis measurements of scattered sun light

    NASA Astrophysics Data System (ADS)

    Wagner, T.; Beirle, S.; Dörner, S.; Penning de Vries, M.; Remmers, J.; Rozanov, A.; Shaiganfar, R.

    2015-05-01

    Absolute radiometric calibrations are important for measurements of the atmospheric spectral radiance. Such measurements can be used to determine actinic fluxes, the properties of aerosols and clouds and the short wave energy budget. Conventional calibration methods in the laboratory are based on calibrated light sources and reflectors and are expensive, time consuming and subject to relatively large uncertainties. Also, the calibrated instruments might change during transport from the laboratory to the measurement sites. Here we present a new calibration method for UV/vis instruments that measure the spectrally resolved sky radiance, like for example zenith sky Differential Optical Absorption Spectroscopy (DOAS-) instruments or Multi-AXis (MAX-) DOAS instruments. Our method is based on the comparison of the solar zenith angle dependence of the measured zenith sky radiance with radiative transfer simulations. For the application of our method clear sky measurements during periods with almost constant aerosol optical depth are needed. The radiative transfer simulations have to take polarisation into account. We show that the calibration results are almost independent from the knowledge of the aerosol optical properties and surface albedo, which causes a rather small uncertainty of about <7%. For wavelengths below about 330 nm it is essential that the ozone column density during the measurements is constant and known.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

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

    PubMed

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

    2015-01-25

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

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

    Microsoft Academic Search

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

    2009-01-01

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

  20. 51V(n, beta)52Cr reaction for neutron dosimetry: development and assessment of a spectrophotometric method for determination of Cr in vanadium at sub ppm level.

    PubMed

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

    2004-08-01

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

  1. Variable path length spectrophotometric probe

    DOEpatents

    O'Rourke, Patrick E. (157 Greenwood Dr., Martiney, GA 30907); McCarty, Jerry E. (104 Recreation Dr., Aiken, SC 29803); Haggard, Ricky A. (1144 Thornwood Drive, North Augusta, SC 29891)

    1992-01-01

    A compact, variable pathlength, fiber optic probe for spectrophotometric measurements of fluids in situ. The probe comprises a probe body with a shaft having a polished end penetrating one side of the probe, a pair of optic fibers, parallel and coterminous, entering the probe opposite the reflecting shaft, and a collimating lens to direct light from one of the fibers to the reflecting surface of the shaft and to direct the reflected light to the second optic fiber. The probe body has an inlet and an outlet port to allow the liquid to enter the probe body and pass between the lens and the reflecting surface of the shaft. A linear stepper motor is connected to the shaft to cause the shaft to advance toward or away from the lens in increments so that absorption measurements can be made at each of the incremental steps. The shaft is sealed to the probe body by a bellows seal to allow freedom of movement of the shaft and yet avoid leakage from the interior of the probe.

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

    EPA Science Inventory

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

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

    Microsoft Academic Search

    S. E Cornell; T. D Jickells

    1999-01-01

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

  4. Fabrication of a bilayer wire grid polarizer in the near infrared wavelength region by using a UV curing nanoimprinting method

    NASA Astrophysics Data System (ADS)

    Lee, Yong Ho; Peranantham, Pazhanisami; Hwangbo, Chang Kwon; Kim, Seok-Min

    2012-11-01

    In this study, we have designed and fabricated an Al bilayer wire grid polarizer (B-WGP) in the near-infrared wavelength region. A finite difference time domain method was employed to design and analyze the subwavelength B-WGP with a period of 450 nm, a grating height of 150 nm, and a duty cycle of 0.5. The high polarization extinction ratio of 1200 indicates that the B-WGP may be used as a normal incidence polarization beam splitter. A subwavelength polymer pattern was fabricated by using an UV curing nanoimprinting method, and an Al thin film was deposited by using a thermal evaporation method. The experimental results show that the transmittance of the TM-wave of the B-WGP is over 50% at wavelengths in the range 1000 ˜ 2000 nm wavelength while the transmittance of the TE-wave is less than 1%, and that the polarization extinction ratio 250. The discrepancies between the simulated and the experimental results are discussed.

  5. A validated UV-HPLC method for determination of chlorogenic acid in Lepidogrammitis drymoglossoides (Baker) Ching, Polypodiaceae

    PubMed Central

    Wen, Jiagen; Kang, Liqun; Liu, Huan; Xiao, Yiyun; Zhang, Xiuzhen; Chen, Yuxiang

    2012-01-01

    Background: Lepidogrammitis drymoglossoides (Baker) Ching (L. drymoglossoides), a member of the Polypodiaceae family, was used in the treatment of numerous diseases. However, none of the potential ingredients and the quality control methods concerning this plant medicine was pronounced. Objective: To identify chlorogenic acid (CGA) from L. drymoglossoides and develop a high performance liquid chromatography (HPLC) assay of CGA. Materials and Methods: UV, TLC, and HPLC were utilized to identify the phytochemicals of L. drymoglossoides and determine the CGA content, respectively. The HPLC conditions were as following: a Phenomenex Luna C18 (2) (250 × 4.6 mm i.d.; 5 ?m particle size; 100 Å pore size) column; the mobile phase of the mixture of acetonitrile and 0.5% aqueous phosphoric acid (11.5:88.5 v/v); the flow rate of 1.0 mL/min and determination wavelength of 327 nm. Results: The proposed HPLC method has been developed and validated. The calibration curve was y = 28328x + 16610 (R2 = 0.9997). The intra-day and inter-day precision and intermediate precision were validated with the RSD less than 5%. The mean recovery rate of the method ranged from 95% to 104%, with the RSD less than 5%. The LOD and LQD values were 0.049 and 0.132 mg/L, respectively. The content of CGA in L. drymoglossoides approximately reached 0.24% (v/v) by the proposed extraction and determination methods. Conclusion: The assay method was simple, convenient, and accurate to the quantification of CGA and can be used for the quality control of the herb. PMID:22923952

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

    PubMed

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

    2014-01-01

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

  7. Spectrophotometric resolution of ternary mixtures of Dexamethasone, Polymyxin B and Trimethoprim in synthetic and pharmaceutical formulations

    Microsoft Academic Search

    J. M. Lemus Gallego; J. Pérez Arroyo

    2001-01-01

    Four spectrophotometric methods are described and applied to resolve ternary mixtures of the corticosteroid Dexamethasone (DEX), the antibiotic Polymyxin B (PLX) and its encouraging Trimethoprim (TMP). The simultaneous determination of these three compounds was firstly accomplished by a derivative method using the “ratio spectrum-zero crossing derivative” (satisfactory results in synthetic mixtures in different ratios and pharmaceutical formulations for DEX and

  8. Spectrophotometric and chemometric studies on the simultaneous determination of two benzodiazepines in human plasma

    Microsoft Academic Search

    Siavash Riahi; Kowsar Bagherzadeh; Nazila Davarkhah; Mohammad Reza Ganjali; Parviz Norouzi

    2011-01-01

    A numerical simple, accurate and precise method based on spectrophotometric data coupled with multivariate calibration methods, PLS and MLR, combined with GA was developed for the simultaneous determination of two benzodiazepines, Clobazam and Flurazepam. A data set of absorption spectra obtained from a calibration set of mixtures containing the compounds was used to build GA-PLS and GA-MLR models. The models

  9. Sensitive spectrophotometric determination of metoclopramide hydrochloride in dosage forms and spiked human urine using vanillin

    Microsoft Academic Search

    O. Zenita Devi; K. Basavaiah; K. B. Vinay; H. D. Revanasiddappa

    A new spectrophotometric method which is simple, sensitive, selective and rapid is described for the determination of metoclopramide hydrochloride (MCP) in bulk drug and in dosage forms using vanillin as the chromogenic agent. The method is based on the condensation reaction between primary aromatic amine group present in MCP with aromatic aldehyde, vanillin to produce an intense yellow colored product.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  11. Simultaneous determination of the absolute configuration of twelve monosaccharide enantiomers from natural products in a single injection by UPLC-UV/MS method

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In natural product chemistry, it is often crucial to determine sugar composition as well as the absolute configuration of each monosaccharide in glycosides. An ultra-performance liquid chromatography method using both photodiode array (PDA) and mass spectrometry detectors (UPLC-UV/MS) was developed....

  12. UV photoresponse properties of ZnO nanorods arrays deposited with CuSCN by SILAR method

    NASA Astrophysics Data System (ADS)

    Li, Shubin; Xu, Jianping; Shi, Shaobo; Shi, Xin; Wang, Xueliang; Wang, Chang; Zhang, Xuguang; Liu, Zeming; Li, Lan

    2015-01-01

    Ultraviolet (UV) photoresponse properties of ZnO nanorods arrays (NRs) deposited with copper thiocyanate (CuSCN) by different successive ionic layer adsorption and reaction (SILAR) cycles were investigated. Compared to the pristine ZnO NRs, the UV photosensitivity increases from 1.65 to 131.53 through lowering the dark current and the photoresponse speed has been obviously improved. As the number of SILAR cycles reaches 120, self-powered UV photoresponse property with fast response speed was observed, which was attributed to the photovoltaic behavior of ZnO/CuSCN.

  13. Telescope Spectrophotometric and Absolute Flux Calibration, and National Security Applications, Using a Tunable Laser on a Satellite

    E-print Network

    Justin Albert; William Burgett; Jason Rhodes

    2006-05-19

    We propose a tunable laser-based satellite-mounted spectrophotometric and absolute flux calibration system, to be utilized by ground- and space-based telescopes. As spectrophotometric calibration may play a significant role in the accuracy of photometric redshift measurement, and photometric redshift accuracy is important for measuring dark energy using SNIa, weak gravitational lensing, and baryon oscillations, a method for reducing such uncertainties is needed. We propose to improve spectrophotometric calibration, currently obtained using standard stars, by placing a tunable laser and a wide-angle light source on a satellite by early next decade (perhaps included in the upgrade to the GPS satellite network) to improve absolute flux calibration and relative spectrophotometric calibration across the visible and near-infrared spectrum. As well as fundamental astrophysical applications, the system proposed here potentially has broad utility for defense and national security applications such as ground target illumination and space communication.

  14. Spectrophotometric determination of plutonium-239 based on the spectrum of plutonium(III) chloride

    SciTech Connect

    Temer, D.J.; Walker, L.F.

    1994-07-01

    This report describes a spectrophotometric method for determining plutonium-239 (Pu-239) based on the spectrum of Pu(III) chloride. The authors used the sealed-reflux technique for the dissolution of plutonium oxide with hydrochloric acid (HCl) and small amounts of nitric and hydrofluoric acids. To complex the fluoride, they added zirconium, and to reduce plutonium to Pu(III), they added ascorbic acid. They then adjusted the solution to a concentration of 2 M HCl and measured the absorbances at five wavelengths of the Pu(III) chloride spectrum. This spectrophotometric determination can also be applied to samples of plutonium metal dissolved in HCl.

  15. Spectrophotometric Estimation of Ketotifen Fumarate from Tablet Formulations

    PubMed Central

    Singhvi, I.; Sachdeva, D.

    2009-01-01

    Two simple and sensitive visible spectrophotometric methods have been developed for the quantitative estimation of ketotifen fumarate from its tablet formulation. The developed methods are based on formation of chloroform extractable colored complex of with 2-nitroso- napthol-4- sulphonic acid and rhodizonic acid. The extracted complex of drug with 2-nitroso- napthol-4- sulphonic acid (method-I), showed absorbance maxima at 436.5 nm and with rhodizonic acid (method-II), showed absorbance maxima at 489.5 nm. The linearity range for both the developed methods was observed in the concentration range of 50-250 µg/ml of drug. Results of analysis for both the developed methods were validated statistically and by recovery studies. PMID:20177462

  16. Spectrophotometric estimation of ketotifen fumarate from tablet formulations.

    PubMed

    Singhvi, I; Sachdeva, D

    2009-01-01

    Two simple and sensitive visible spectrophotometric methods have been developed for the quantitative estimation of ketotifen fumarate from its tablet formulation. The developed methods are based on formation of chloroform extractable colored complex of with 2-nitroso- napthol-4- sulphonic acid and rhodizonic acid. The extracted complex of drug with 2-nitroso- napthol-4- sulphonic acid (method-I), showed absorbance maxima at 436.5 nm and with rhodizonic acid (method-II), showed absorbance maxima at 489.5 nm. The linearity range for both the developed methods was observed in the concentration range of 50-250 microg/ml of drug. Results of analysis for both the developed methods were validated statistically and by recovery studies. PMID:20177462

  17. New acyclic 1,2,4-triazole-based Schiff base hydrazone: Synthesis, characterization, spectrophotometric and computational studies

    NASA Astrophysics Data System (ADS)

    Khanmohammadi, Hamid; Erfantalab, Malihe; Azimi, Golamhassan

    2013-03-01

    A new 1,2,4-triazole-based Schiff base hydrazone with N, O, S donor set of atoms, H4L, has been prepared by condensation reaction of N,N'-bis(3-formyl-5-methylsalicylidene)ethane-1,2-diamine, H2L, with 4-amino-3-(4-pyridyl)-5-mercapto-1,2,4-triazole. The structure of H4L was characterized by using FT-IR, UV-Vis and 1H NMR spectroscopic methods as well as elemental analysis data. The formation constants of copper(II), cadmium(II), mercury(II) and silver(I) complexes of H4L in DMSO were calculated using a hard model chemometrics method applying the spectrophotometric data. The protonation constants of H4L were also measured in DMSO-water (1:10) mixture. Furthermore, 1H chemical shifts of H4L were studied by the gauge independent atomic orbital (GIAO) and continuous set of gauge transformations (CSGTs) methods at the level of density functional theory using B3LYP/6-311++G* basis sets in gas phase. The computed chemical shifts are in reasonably good agreement with the experimental data.

  18. A comparative study between PCR and PLS in simultaneous spectrophotometric determination of diphenylamine, aniline, and phenol: Effect of wavelength selection.

    PubMed

    Hemmateenejad, Bahram; Akhond, Morteza; Samari, Fayezeh

    2007-07-01

    Partial least squares (PLS) and principal component regression (PCR) have received considerable attention in the chemometrics for multicomponent analysis where superiority of one over another is a challenging problem yet. Considering the effect of wavelength selection, a comparison was made between PCR and PLS methods by application those to simultaneous spectrophotometric determination of diphenylamine (DPA), a compound from the third European Union list of priority pollutants, and its environmentally related products aniline and phenol. The UV absorbance spectra of the methanolic solutions of the analytes were measured in the concentration ranges of 1.0-10.0 microg mL(-1) and then subjected to PCR and PLS. The models refinement procedure and validation was performed by cross-validation. A modified changeable size moving windows strategy, where optimized the intervals between the sensors in a selected windows, was also proposed to select the more informative spectral regions for each of the analytes. It was found that wavelength selection improved the quality of predictions for both regression methods whereas more reliable results were obtained by removing of the highly collinear neighboring wavelengths. The resultant data explained that PLS produced more or less better results when whole spectral data were used but in the case of selected wavelength regions both methods produced similar results and no comments could be given about the superiority of one against another. The major difference was obtaining the higher number of factors for PCR, which is not a significant problem. PMID:17049915

  19. Spectrophotometric Determination of Total Sulfite in White Wine Samples Using Crude Extracts from Flowers

    NASA Astrophysics Data System (ADS)

    Flora Barbosa Soares, Márlon Herbert; Ramos, Luiz Antonio; Tadeu Gomes Cavalheiro, Éder

    2002-09-01

    A didactic spectrophotometric method for determining the sulfite content in white wine samples is proposed. It is based upon a discoloring reaction between flower anthocyanins and the sulfite in basic media. Students' results obtained from iodometric data agreed well with results obtained by the proposed procedure. The use of natural dyes attracted students' interest, enhancing the learning process.

  20. Determination of ibuprofen in combined dosage forms and cream by direct UV spectrophotometry after solid-phase extraction.

    PubMed

    Sunaric, Slavica; Petkovic, Milica; Denic, Marko; Mitic, Snezana; Pavlovic, Aleksandra

    2013-01-01

    Solid-phase extraction method followed by direct UV spectrophotometry at 264 nm was developed and applied for the selective ibuprofen determination in two-component formulation of ibuprofen and pseudoephedrine-HCl, combined powder which contains ibuprofen in the form of salt with L-arginine and 10% ibuprofen cream. Procedures for ibuprofen determination in complex pharmaceutical preparations by direct UV spectrophotometry lack selectivity because of interferences of other active substances and fat components. A limited number of spectrophotometric methods applicable to these samples are based on derivative (first and second-order) UV spectroscopy. Common HPLC procedures are more selective but more expensive and for creams also require some type of extraction because the large amount of oily excipients would clog up the column. The proposed solid-phase extraction method proved to be suitable for analysis of ibuprofen in combined tablets, powders and creams by direct UV spectrophotometry. Also the method provides an effective clean-up of the cream and allows ibuprofen determination by HPLC analysis. For the extraction three different commercial sorbents were tested: anion exchange Oasis MAX, hydrophilic-lipophilic balanced Oasis HLB and reverse-phase Chromabond C18ec. The optimization of the SPE method was first done on standard ibuprofen solutions and then the suitability of the method was checked on solutions of commercial pharmaceutical samples. The method yields good results for all three types of commercial preparations on the anion-exchange Oasis MAX cartridges, with recoveries of 90-100.2%. The interferences in UV analysis were not registered and good precision (RSD < 6%) was obtained. The present method has been verified as accurate as the reference HPLC with the great advantage of less expensive instrumentation. For this reason, the method would be suitable for a routine and rapid drug quality control. PMID:23757930

  1. An online aerosol retrieval algorithm using OMI near-UV observations based on the optimal estimation method

    NASA Astrophysics Data System (ADS)

    Jeong, U.; Kim, J.; Ahn, C.; Torres, O.; Liu, X.; Bhartia, P. K.; Spurr, R. J. D.; Haffner, D.; Chance, K.; Holben, B. N.

    2015-06-01

    An online version of the OMI (Ozone Monitoring Instrument) near-ultraviolet (UV) aerosol retrieval algorithm was developed to retrieve aerosol optical thickness (AOT) and single scattering albedo (SSA) based on the optimal estimation (OE) method. Instead of using the traditional look-up tables for radiative transfer calculations, it performs online radiative transfer calculations with the Vector Linearized Discrete Ordinate Radiative Transfer (VLIDORT) model to eliminate interpolation errors and improve stability. The OE-based algorithm has the merit of providing useful estimates of uncertainties simultaneously with the inversion products. The measurements and inversion products of the Distributed Regional Aerosol Gridded Observation Network campaign in Northeast Asia (DRAGON NE-Asia 2012) were used to validate the retrieved AOT and SSA. The retrieved AOT and SSA at 388 nm have a correlation with the Aerosol Robotic Network (AERONET) products that is comparable to or better than the correlation with the operational product during the campaign. The estimated retrieval noise and smoothing error perform well in representing the envelope curve of actual biases of AOT at 388 nm between the retrieved AOT and AERONET measurements. The forward model parameter errors were analyzed separately for both AOT and SSA retrievals. The surface albedo at 388 nm, the imaginary part of the refractive index at 354 nm, and the number fine mode fraction (FMF) were found to be the most important parameters affecting the retrieval accuracy of AOT, while FMF was the most important parameter for the SSA retrieval. The additional information provided with the retrievals, including the estimated error and degrees of freedom, is expected to be valuable for future studies.

  2. Fabrication of ZnO crystals by UV-laser annealing on ZnO nanoparticles prepared by laser ablation method

    NASA Astrophysics Data System (ADS)

    Shimogaki, T.; Kawahara, H.; Higashihata, M.; Ikenoue, H.; Nakamura, D.; Nakata, Y.; Okada, T.

    2014-03-01

    Various zinc oxide (ZnO) nanocrystals are expected as new building blocks for optoelectronic devices. Among them, we have studied about fabricating ZnO nanowires using nanoparticle-assisted pulsed laser deposition (NAPLD). Recently, we achieved to fabricate the periodically-aligned ZnO nanowires with a period of from 4 to 5 ?m using interfering four-beams of nanosecond ultraviolet (UV) laser processing. ZnO nanowires with diameters of several dozen nanometers were grown on the ZnO buffer layer prepared by pulsed laser deposition at the low-chamber pressure of 3 Pa. Additionally, crystallization of ZnO nanoparticles collected on a sapphire substrate was achieved by UV-laser annealing. In this method, ZnO nanoparticles were collected at room temperature, then they were laser-annealed with a KrF excimer laser. The particle size increased by instantaneous melting and aggregation of ZnO nanoparticles because of the high absorption efficiency of ZnO in the UV spectral region. It was found that the optical property was improved by UV-laser annealing process. Additionally, their x-ray diffraction peaks of wurtzite ZnO crystals had narrower full width half maximum than those before laser annealing.

  3. Simultaneous determination of phenytoin, barbital and caffeine in pharmaceuticals by absorption (zero-order) UV spectra and first-order derivative spectra—multivariate calibration methods

    Microsoft Academic Search

    A. Abbaspour; R. Mirzajani

    2005-01-01

    The quantitative predictive abilities of partial least squares (PLS-1) and principle component regression (PCR) on absorption (zero-order) UV spectra are compared with the results obtained by the use of these multivariate calibration methods on first-order derivative spectra. Both approaches were satisfactorily applied to the simultaneous determination of these drugs in synthetic and pharmaceutical mixtures. Significant advantages were found in the

  4. Preparation and characterization of high photoactive TiO 2 catalyst using the UV irradiation-induced sol-gel method

    Microsoft Academic Search

    Jianhua Liu; Rong Yang; Songmei Li

    2006-01-01

    High photoactive TiO2 catalyst was prepared using the sol-gel method through UV irradiation during the formation stage of nuclei. The surface morphology and microstructure of the prepared catalyst were characterized using scanning electron microscopy (SEM), X-ray diffraction patterns (XRD), and Fourier transform infrared spectroscopy (FT-IR). The photoactivity was evaluated by the degradation of methylene blue. The results show that the

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

    SciTech Connect

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

    2002-01-01

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

  6. Chemical fingerprint and metabolic fingerprint analysis of Danshen injection by HPLC–UV and HPLC–MS methods

    Microsoft Academic Search

    Jin-lan Zhang; Ming Cui; Yun He; Hai-lan Yu; De-an Guo

    2005-01-01

    HPLC–UV and HPLC–MS techniques were used in fingerprint analysis of Danshen injection and its raw materials (roots and rhizoma of Salvia miltiorrhiza). HPLC profiles of Danshen injections from a Chinese pharmaceutical factory and their raw materials were established as their characteristic fingerprint and employed to assess their consistency and difference. To develop the representative fingerprint of Danshen injection, 10 batches

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

    PubMed

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

    2014-12-01

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

  8. Spectrophotometric determination of ethanolamines in lubricating emulsions{copyright}

    SciTech Connect

    Fernando, L.A. [Kaiser Aluminum & Chemical Corporation, Pleasanton, CA (United States)

    1995-08-01

    A method is described for determining ethanolamines in lubricating emulsions. The ethanolamine is partitioned into an aqueous phase, reacted with Cu{sup 11} to form a blue solution and the concentration is determined spectrophotometrically. The wavelengths of maximum absorption ranged from 625-680 nm. Recoveries ranged from 94%-101% and the RSD for the method averaged 4%. The analytical procedures are simple, do not require expensive instrumentation, and are readily adaptable to routine analyses. The absorption spectra of the complexes can be a useful tool in determining the class of amine alcohol present in unknown emulsions. Results of the subject method are also compared with alkalinity measurements via potentiometric titrations. 9 refs., 2 figs., 4 tabs.

  9. [Catalytic kinetic spectrophotometric determination of nickel in alloys].

    PubMed

    Xia, Chang-bin; Huang, Nian-dong; Wang, Hong-jun; He, Xiang-zhu

    2004-11-01

    In (CH2)6N4-HCl buffer solution and in the presence of OP emulsifier trace Ni(II) catalyzes strongly the decolorization reaction of Rhodamine B (RhB) by oxidizing with H2O2, and its catalytic extent is linear with the contents of Ni(II) in a certain range. Based on this study, a novel spectrophotometric method for determining Ni(II) was developed. The results show that the maximum absorption of the complex is at 550 nm, the detection limit of the method is 0.4 microg x L(-1) for Ni(II), and Beer's law is obeyed for Ni(II) in the range of 0-0.3 mg x L(-1). The method has been applied to the determination of Ni in FeNiCr alloys with satisfactory results. PMID:15762512

  10. Spectrophotometric distances to Galactic H II regions

    NASA Astrophysics Data System (ADS)

    Moisés, A. P.; Damineli, A.; Figuerêdo, E.; Blum, R. D.; Conti, P. S.; Barbosa, C. L.

    2011-02-01

    We present a near-infrared study of the stellar content of 35 H II regions in the Galactic plane, 24 of which have been classified as giant H II regions. We have selected these optically obscured star-forming regions from the catalogues of Russeil, Conti & Crowther and Bica et al. In this paper, we have used the near-infrared domain J-, H- and Ks-band colour images to visually inspect the sample. Also, we have used colour-colour and colour-magnitude diagrams to indicate ionizing star candidates, as well as the presence of young stellar objects such as classical T Tauri stars and massive young stellar objects (MYSOs). We have obtained Spitzer Infrared Array Camera images for each region to help further characterize them. Spitzer and near-infrared morphology were used to place each cluster in an evolutionary phase of development. Spitzer photometry was also used to classify the MYSOs. A comparison of the main sequence in the colour-magnitude diagrams for each observed cluster was used to infer whether or not the cluster kinematic distance is consistent with brightnesses of the stellar sources. We find qualitative agreement for a dozen of the regions, but about half the regions have near-infrared photometry that suggests they may be closer than the kinematic distance. A significant fraction of these already have spectrophotometric parallaxes that support smaller distances. These discrepancies between kinematic and spectrophotometric distances are not a result of the spectrophotometric methodologies, as independent non-kinematic measurements are in agreement with the spectrophotometric results. For instance, the trigonometric parallaxes of star-forming regions were collected from the literature and show the same effect of smaller distances when compared to the kinematic results. In our sample of H II regions, most of the clusters are evident in the near-infrared images. Finally, it is possible to distinguish among qualitative evolutionary stages for these objects.

  11. Kinetic-spectrophotometric determination of palladium in hydrogenation catalyst by its catalytic effect on the oxidation of pyrogallol red by hydrogen peroxide

    Microsoft Academic Search

    Ali A Ensafi; M Keyvanfard

    2002-01-01

    A new kinetic-spectrophotometric method is described for the determination of ultra trace amounts of Pd(II). The methods based on catalytic action of Pd(II) on the oxidation of pyrogallol red (PGR) with hydrogen peroxide at pH 9.7. The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of the PGR at 540 nm, for the first 4.5 min from initiation

  12. Spectrophotometric Determination of Esomeprazole Magnesium in Commercial Tablets Using 5-Sulfosalicylic Acid and N-Bromosuccinimide

    Microsoft Academic Search

    Nafisur Rahman; Zehra Bano; Syed Najmul; Hejaz Azmi

    Two simple, sensitive and economical spectrophotometric methods have been developed for the de- termination of esomeprazole magnesium in commercial dosage forms. Method Ais based on the reaction of esomeprazole magnesium with 5-sulfosalicylic acid in methanol to form a yellow product, which ab- sorbs maximally at 365 nm. Method B utilizes the reaction of esomeprazole magnesium with N-bromo- succinimide in acetone-chloroform

  13. Spectrophotometric determination of triclosan in personal care products

    NASA Astrophysics Data System (ADS)

    Lu, Huihui; Ma, Hongbing; Tao, Guanhong

    2009-09-01

    A spectrophotometric method for the determination of triclosan in personal care products was proposed. It was based on the reaction of sodium nitrite with p-sulfanilic acid in an acidic medium to form diazonium ion, with which triclosan further formed an azo compound in an alkaline medium. The resulting yellow colored product has a maximum absorption at 452 nm. A good linear relationship ( r = 0.9999) was obtained in the range of 0-30 mg L -1 triclosan. A detection limit of 0.079 g L -1 was achieved and the relative standard deviation was 0.24% ( n = 11) at 14 mg L -1 triclosan. The proposed method has been applied to the analyses of triclosan in several personal care products and the results were in good agreement with those obtained by high-performance liquid chromatography.

  14. Are You UV Safe?

    NSDL National Science Digital Library

    Brenda Capobianco

    2006-09-01

    Students may be slathered with SPF 30 sunscreen all summer at the beach or pool, but what do they know about ultraviolet (UV) light radiation and absorption? How could we help them find out the science behind this important health precaution? We found the perfect opportunity when we developed this series of practical strategies to promote students' investigation skills. We integrated several scientific processes into a lesson on UV light radiation and absorption for fourth-grade students and preservice elementary methods students. These teaching tools help students develop their abilities to ask testable questions, plan and design investigations, and interpret what they find.

  15. Enzymatic determination of vitamin A in pharmaceutical formulations with spectrophotometric detection

    NASA Astrophysics Data System (ADS)

    Rishi, Lubna; Asgher, Mohammad; Yaqoob, Mohammad; Waseem, Amir; Nabi, Abdul

    2009-06-01

    An enzymatic method for the determination vitamin A (retinol) is reported using soluble and immobilized alcohol dehydrogenase, isolated from rabbit liver. The reaction is based on the oxidation of retinol and simultaneous reduction of NAD + to NADH followed by spectrophotometric detection at 340 nm. The calibration graph was linear over the range of 2.0-10 ?M with correlation coefficients of 0.9967 and 0.9992 ( n = 5) for soluble and immobilized alcohol dehydrogenase respectively, with relative standard deviations ( n = 3) in the range of 0.5-1.2%. The limit of detection was lower than 1.0 ?M. The proposed method was applied to determine vitamin A in pharmaceuticals, and the results obtained were in reasonable agreement with the amount labeled. The results were compared using spectrophotometric reference method, and no significant difference was found between the results of the both methods.

  16. Preconcentration of Sn (II) using the methylene blue on the activated carbon and its determination by spectrophotometry method.

    PubMed

    Khodadoust, Saeid; Cham Kouri, Narges

    2014-04-01

    A simple and accurate spectrophotometric method for determination of trace amounts of Sn (II) ion in soil sample was developed by using the methylene blue (MB) in the presence of activated carbon (AC) as the adsorbent Solid Phase Extraction (SPE) of Sn (II) and then determined by UV-Vis. The Beer's law is obeyed over the concentration range of 1-80ngmL(-1) of Sn (II) with the detection limits of 0.34ngmL(-1). The influence of type and volume of eluent, concentration of MB, pH, and amount of AC on sensitivity of spectrophotometric method were optimized. The method has been successfully applied for Sn (II) ion determination in soil sample. PMID:24394524

  17. Application of spectroscopic methods for identification (FT-IR, Raman spectroscopy) and determination (UV, EPR) of quercetin-3-O-rutinoside. Experimental and DFT based approach

    NASA Astrophysics Data System (ADS)

    Paczkowska, Magdalena; Lewandowska, Kornelia; Bednarski, Waldemar; Mizera, Miko?aj; Podborska, Agnieszka; Krause, Anna; Cielecka-Piontek, Judyta

    2015-04-01

    Vibrational (FT-IR, Raman) and electronic (UV, EPR) spectral measurements were performed for an analysis of rutin (quercetin-3-O-rutinoside) obtained from Rutaofficinalis. The identification of rutin was done with the use of FT-IR and Raman spectra. Those experimental spectra were determined with the support of theoretical calculations based on a DFT method with the B3LYP hybrid functional and 6-31G(d,p) basis set. The application of UV and EPR spectra was found to be a suitable analytical approach to the evaluation of changes in rutin exposed to certain physicochemical factors. Differences in absorbance observed in direct UV spectra were used to monitor changes in the concentration of rutin in degraded samples. Spectra of electron paramagnetic resonance allowed studying the process of free-radical quenching in rutin following its exposure to light. The molecular electrostatic potential (MEP) and frontier molecular orbitals (LUMO-HOMO) were also determined in order to predict structural changes and reactive sites in rutin.

  18. Application of spectroscopic methods for identification (FT-IR, Raman spectroscopy) and determination (UV, EPR) of quercetin-3-O-rutinoside. Experimental and DFT based approach.

    PubMed

    Paczkowska, Magdalena; Lewandowska, Kornelia; Bednarski, Waldemar; Mizera, Miko?aj; Podborska, Agnieszka; Krause, Anna; Cielecka-Piontek, Judyta

    2015-04-01

    Vibrational (FT-IR, Raman) and electronic (UV, EPR) spectral measurements were performed for an analysis of rutin (quercetin-3-O-rutinoside) obtained from Rutaofficinalis. The identification of rutin was done with the use of FT-IR and Raman spectra. Those experimental spectra were determined with the support of theoretical calculations based on a DFT method with the B3LYP hybrid functional and 6-31G(d,p) basis set. The application of UV and EPR spectra was found to be a suitable analytical approach to the evaluation of changes in rutin exposed to certain physicochemical factors. Differences in absorbance observed in direct UV spectra were used to monitor changes in the concentration of rutin in degraded samples. Spectra of electron paramagnetic resonance allowed studying the process of free-radical quenching in rutin following its exposure to light. The molecular electrostatic potential (MEP) and frontier molecular orbitals (LUMO-HOMO) were also determined in order to predict structural changes and reactive sites in rutin. PMID:25589394

  19. Comparative Study of Three Methods for Affinity Measurements: Capillary Electrophoresis Coupled with UV Detection and Mass Spectrometry, and Direct Infusion Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Mironov, Gleb G.; Logie, Jennifer; Okhonin, Victor; Renaud, Justin B.; Mayer, Paul M.; Berezovski, Maxim V.

    2012-07-01

    We present affinity capillary electrophoresis and mass spectrometry (ACE-MS) as a comprehensive separation technique for label-free solution-based affinity analysis. The application of ACE-MS for measuring affinity constants between eight small molecule drugs [ibuprofen, s-flurbiprofen, diclofenac, phenylbutazone, naproxen, folic acid, resveratrol, and 4,4'-(propane-1,3-diyl) dibenzoic acid] and ?-cyclodextrin is described. We couple on-line ACE with MS to combine the separation and kinetic capability of ACE together with the molecular weight and structural elucidation of MS in one system. To understand the full potential of ACE-MS, we compare it with two other methods: Direct infusion mass spectrometry (DIMS) and ACE with UV detection (ACE-UV). After the evaluation, DIMS provides less reliable equilibrium dissociation constants than separation-based ACE-UV and ACE-MS, and cannot be used solely for the study of noncovalent interactions. ACE-MS determines apparent dissociation constants for all reacting small molecules in a mixture, even in cases when drugs overlap with each other during separation. The ability of ACE-MS to interact, separate, and rapidly scan through m/z can facilitate the simultaneous affinity analysis of multiple interacting pairs, potentially leading to the high-throughput screening of drug candidates.

  20. A fast tree-based method for estimating column densities in Adaptive Mesh Refinement codes Influence of UV radiation field on the structure of molecular clouds

    E-print Network

    Valdivia, Valeska

    2014-01-01

    Context. Ultraviolet radiation plays a crucial role in molecular clouds. Radiation and matter are tightly coupled and their interplay influences the physical and chemical properties of gas. In particular, modeling the radiation propagation requires calculating column densities, which can be numerically expensive in high-resolution multidimensional simulations. Aims. Developing fast methods for estimating column densities is mandatory if we are interested in the dynamical influence of the radiative transfer. In particular, we focus on the effect of the UV screening on the dynamics and on the statistical properties of molecular clouds. Methods. We have developed a tree-based method for a fast estimate of column densities, implemented in the adaptive mesh refinement code RAMSES. We performed numerical simulations using this method in order to analyze the influence of the screening on the clump formation. Results. We find that the accuracy for the extinction of the tree-based method is better than 10%, while the ...

  1. A UV-transparent passive concentrator/spectrum deconvolution method for simultaneous detection of endocrine disrupting chemicals (EDCs) and related contaminants in natural waters.

    PubMed

    Kibbey, Tohren C G; Chen, Lixia; Singhaputtangkul, Natee; Sabatini, David A

    2009-08-01

    Suspected endocrine disrupting chemicals (EDCs) have been widely detected in the environment, and are a source of increasing concern. One of the major challenges in assessing the risk associated with EDCs in the environment is that their environmental concentrations are typically extremely low - on the order of ngL(-1) to microgL(-1) - making them difficult to quantify without extensive pre-concentration procedures. Further complicating their detection is the fact that they are present in mixtures, sometimes with tens to hundreds of other compounds (pharmaceuticals, personal care products, detergents, natural organic matter). The objective of the work described here was to develop a method for rapid monitoring and detection of EDCs at trace concentrations in natural waters. The method makes use of a UV-transparent polymer-based concentrator to be used as a passive sampling device. The UV-transparent polymer-based concentrator serves both as a solid phase extraction medium to concentrate EDCs for analysis and exclude many compounds likely to interfere with detection (fines, macromolecules such as organic matter, ionic surfactants), and as an analytical optical cell, allowing rapid EDC quantification without labor-intensive pre-concentration procedures. A full-spectrum deconvolution technique is used to determine EDC concentrations from measured UV absorbance spectra in the polymer. Experiments were conducted to measure partitioning rate behavior and partition coefficients between the selected polymer (a functional polydimethylsiloxane) and water for seven compounds known or suspected of being endocrine disruptors: estrone, progesterone, estradiol, 2,6-di-tert-butyl-1,4-benzoquinone, phenanthrene, triclosan, and 4-nonylphenol. The method was tested for its ability to detect and quantify individual compounds in mixtures containing up to six components. Results show the method to have selectivity suitable for rapid screening applications at many sites where multiple compounds are present. PMID:19539350

  2. Development and validation of an anion-exchange LC-UV method for the quantification and purity determination of the DNA plasmid pDERMATT.

    PubMed

    Quaak, S G L; Nuijen, B; Haanen, J B A G; Beijnen, J H

    2009-02-20

    The pDERMATT (plasmid DNA encoding recombinant MART-1 and tetanus toxin fragment-c) plasmid is a novel in-house developed anti-cancer vaccine which encodes a melanoma associated epitope (Mart-1) and an immuno stimulatory sequence (tetanus toxin fragment-c). The pharmaceutical development of pDERMATT necessitated the availability of an assay for the quantification and purity determination of pDERMATT active pharmaceutical ingredient (API), the produced bulk drug and its pharmaceutical dosage form. An anion-exchange liquid chromatographic method (AEX-LC) with ultraviolet (UV) detection was developed, which is based on separation on a non porous anion-exchange (NPR AEX) column with a mobile phase gradient of 0.45-0.53M NaCl in 20mM Tris-HCl 10% isopropanol (IPA) pH 9 and UV detection at 260 and 280nm. The method was found to be precise, accurate and linear over a concentration range of 5-150microg/ml. The supercoiled topoisoform of pDERMATT was well separated from the linear and open-circular form, the main degradation products formed during stress testing, confirming its stability-indicating capability. The use of photo diode array (PDA) detection enabled us to confirm all visible peaks to contain DNA. Additionally capillary gel electrophoresis (CGE) showed the same peak profile as the developed HPLC method. The developed LC-UV method will be used for the pharmaceutical quality control of pDERMATT API, bulk drug and its pharmaceutical dosage form. PMID:19111423

  3. Spectrophotometric determination of trifluralin in commercial formulations and agricultural samples using factorial design

    Microsoft Academic Search

    Jasmin Shah; M. Rasul Jan; Farhat-un-nisa Shehzad; Behisht Ara

    2010-01-01

    A simple spectrophotometric method was developed for determination of trifluralin in commercial formulation and food samples.\\u000a The method was based on the hydrolysis of trifluralin with sodium hydroxide to form 2,6-dinitro-4-trifluoromethylaniline.\\u000a The resultant aniline group was diazotized with nitrate in acidic media and the diazotized product was coupled with ?-naphthol\\u000a to form red colored product having ?max 550 nm. The reaction

  4. Spectrophotometric resolution of ternary mixtures of Tartrazine, Patent Blue V and Indigo Carmine in commercial products

    Microsoft Academic Search

    J. J. Berzas; J. Rodr??guez Flores; M. J. Villaseñor Llerena; N. Rodr??guez Fariñas

    1999-01-01

    Four spectrophotometric methods are described and applied to resolve ternary mixtures of the food dyes Tartrazine (E-102), Patent Blue V (E-131) and Indigo Carmine (E-132). The simultaneous determination of these three dyes was firstly accomplished by two derivative methods using the “first derivative” and the “ratio spectrum-zero crossing derivative”, which were satisfactorily used to determine synthetic mixtures of these colorants

  5. Spectrophotometric Determination of Cadmium(II) Using p,p??Dinitro?SYM?Diphenylcarbazid in Aqueous Solutions

    Microsoft Academic Search

    Laura Bulgariu; Dumitru Bulgariu; Ioan Sârghie

    2005-01-01

    A sensitive and selective spectrophotometric method is proposed for the rapid determination of cadmium(II) using, p,p??dinitro?sym?diphenylcarbazid, directly in aqueous solution. The reaction between cadmium(II) and p,p??dinitro?sym?diphenylcarbazid occurs immediately in strong basic media (0.02 N sodium hydroxide solution). The complex shows a maximum of absorption at 630–640 nm, and the absorbance remains stable for at least 24 h. The method allows the cadmium determination

  6. Spectrophotometric determination of pipazethate HCl, dextromethorphan HBr and drotaverine HCl in their pharmaceutical preparations

    Microsoft Academic Search

    Alaa S. Amin; Ragaa El-Sheikh; Faten Zahran; Ayman Abou El-fetouh Gouda

    2007-01-01

    A simple, accurate and highly sensitive spectrophotometric method is proposed for the rapid determination of pipazethate hydrochloride, dextromethorphan hydrobromide and drotaverine hydrochloride using chromotrope 2B (C2B) and chromotrope 2R (C2R). The method consists of extracting the formed ion-associates into chloroform in the case of pipazethate HCl and dextromethorphan HBr or into methylene chloride in the case of drotaverine HCl. The

  7. Spectrophotometric Estimation of L- 5Hydroxytryptophan in Griffonia simplicifolia Extracts and Dosage Forms?

    Microsoft Academic Search

    Gottumukkala V. Subbaraju; Sukala Kannababua; Katta Vijayakumar; Papolu B. S. Murthy; Mulabagal Vanisree; Hsin-Sheng Tsay

    A simple, sensitive and precise spectrophotometric method has been developed for the determination of L-5-Hydroxytryptophan in Griffonia simplicifolia seed extracts and dosage forms. L-5-Hydroxytryptophan gives a blue colored chromogen with Folin-Ciocalteu reagent under alkaline conditions with absorption maxima at 736 nm. The chromogen obeys Beer's law in the concentration range 1-10 ? g\\/ml. The proposed method is reproducible and statistically

  8. Distribution and nature of UV absorbers on Triton's surface

    NASA Technical Reports Server (NTRS)

    Stern, S. Alan

    1995-01-01

    Substantial evidence suggests that a UV spectrally Absorbing Material (UV-SAM) exists on Triton's surface. This evidence is found in the positive slope in Triton's spectrum from the UV to the near-IR, and the increasing contrast in Triton's light curve in the blue and UV. Although it is now widely-thought that UV-SAMs exist on Triton, little is known about their distribution and spectral properties. The goal of this NDAP Project is to determine the spatial distribution and geological context of the UV-SaM material. We hope to determine if UV-SAMs on Triton are correlated with geologic wind streaks, craters, calderas, geomorphic/topographic units, regions containing (or lacking) volatile frosts, or some other process (e.g., magnetospheric interactions). Once the location and distribution of UV-SAMs has been determined, further constraints on their composition cable made by analyzing the spectrographic data set. To accomplish these goals, various data sets will be used, including Voyager 2 UV and visible images of Triton's surface, IUE and HST spectra of Triton, and a geologic map of the surface based on voyager 2 and spectrophotometric data. The results of this research will be published in the planetary science literature.

  9. Distribution and nature of UV absorbers on Trition's surface

    NASA Technical Reports Server (NTRS)

    Stern, S. Alan

    1995-01-01

    Substantial evidence suggests that a UV (ultraviolet) Spectrally Absorbing Material (UV-SAM) exists on Triton's surface. This evidence is found in the positive slope in Triton's spectrum from the UV to the near-IR, and the increasing contrast in Triton's light curve in the blue and UV. Although it is now widely-thought that UV-SAM's exist on Triton, little is known about their distribution and spectral properties. The goal of this NDAP Project is to determine the spatial distribution and geological context of the UV-SAM material. We hope to determine if UV-SAM's on Triton are correlated with geologic wind streaks, craters, calderas, geomorphic/topographic units, regions containing (or lacking) volatile frosts, or some other process (e.g., magnetospheric interactions). Once the location and distribution of UV-SAM's has been determined, further constraints on their composition can be made by analyzing the spectrographic data set. To accomplish these goals, various data sets will be used, including Voyager 2 UV and visible images of Triton's surface, IUE and HST spectra of Triton, and a geologic map of the surface based on Voyager 2 and spectrophotometric data. The results of this research will be published in the planetary science literature.

  10. Distribution and nature of UV absorbers on Triton's surface

    NASA Technical Reports Server (NTRS)

    Stern, S. Alan

    1994-01-01

    Substantial evidence suggests that a UV Spectrally Absorbing Material (UV-SAM) exists on Triton's surface. This evidence is found in the positive slope in Triton's spectrum from the UV to the near-IR, and the increasing contrast in Triton's light curve in the blue and UV. Although it is now widely-thought that UV-SAM's exist on Triton, little is known about their distribution and spectral properties. The goal of this NDAP Project is to determine the spatial distribution and geological context of the UV-SAM material. We hope to determine if UV-SAM's on Triton are correlated with geologic wind streaks, craters, calderas, geomorphic/topographic units, regions containing (or lacking) volatile frosts, or some other process (e.g., magnetospheric interactions). Once the location and distribution of UV-SAM's has been determined, further constraints on their composition can be made by analyzing the spectrographic data set. To accomplish these goals, various data sets will be used, including Voyager 2 UV and visible images of Triton's surface, IUE and HST spectra of Triton, and a geologic map of the surface based on Voyager 2 and spectrophotometric data. The results of this research will be published in the planetary science literature.

  11. Simultaneous determination of 15 phenolic compounds and caffeine in teas and mate using RP-HPLC/UV detection: method development and optimization of extraction process.

    PubMed

    Bae, In Kyung; Ham, Hyeon Mi; Jeong, Min Hee; Kim, Dong Ho; Kim, Ho Jin

    2015-04-01

    A reversed-phase high performance liquid chromatographic coupled to ultraviolet detection (RP-HPLC/UV) method was developed for simultaneous determination of 15 phenolic compounds and caffeine in TEAS (green tea, oolong tea, black tea and mate). Furthermore, the extraction process of total phenolic contents (TPC) from TEAS were optimized using response surface methodology (RSM) based on a central composite design (CCD) and then applied to extraction of TEAS. The best conditions obtained using the model were as follow: green tea--extraction time of 123 min, extraction temperature of 70 °C and ethanol concentration of 75%, oolong tea--extraction time of 98 min, extraction temperature of 70 °C and ethanol concentration of 69%, black tea--extraction time of 105 min, extraction temperature of 71 °C and ethanol concentration of 63%, and mate--extraction time of 103 min, extraction temperature of 71 °C and ethanol concentration of 61%. Among the extraction methods used in this study, heat-reflux extraction was found to result in the highest values of TPC. The chromatographic peaks of the 16 studied compounds were successfully identified by comparing their retention time and UV spectra with the reference standards. Method validation was performed by means of linearity, sensitivity, selectivity, accuracy and precision. The developed method was found to be simple, specific and reliable and is suited for routine analysis of phenolic compounds and caffeine in TEAS. PMID:25442580

  12. Quantitative HPLC Analysis of Rosmarinic Acid in Extracts of "Melissa officinalis" and Spectrophotometric Measurement of Their Antioxidant Activities

    ERIC Educational Resources Information Center

    Canelas, Vera; da Costa, Cristina Teixeira

    2007-01-01

    The students prepare tea samples using different quantities of lemon balm leaves ("Melissa officinalis") and measure the rosmarinic acid contents by an HPLC-DAD method. The antioxidant properties of the tea samples are evaluated by a spectrophotometric method using a radical-scavenging assay with DPPH. (2,2-diphenyl-1-picrylhydrazyl). Finally the…

  13. Spectrophotometric determination of ofloxacin in pharmaceuticals by redox reaction

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

    Two simple spectrophotometric methods have been developed to analyze ofloxacin (OFX) in pharmaceuticals. The methods are based on the oxidation of OFX by a measured excess of cerium(IV) sulfate in H2SO4 medium. This was followed by the determination of the unreacted oxidant by reacting it with either p-toluidine ( p-TD) and measuring the absorbance at 525 nm (method A) or o-dianisidine ( o-DA) and measuring the absorbance at 470 nm (method B). In both methods, the amount of cerium(IV) sulfate reacted corresponds to the amount of OFX. Calibration graphs were linear over the ranges of 0-120 and 0-4 g/ml OFX for methods A and B, respectively. The calculated molar absorptivity (2.34?103 and 5.99?104), Sandell sensitivity, and limit of quantification for the methods are reported. The intra-day precision (%RSD) and accuracy (%RE) were < 8.0 and ? 4.0%, respectively, and the inter-day RSD and RE values were within 5 and 4.0%, respectively. The applicability of the methods was demonstrated by determining OFX in tablets with an accuracy (%RE) of < 3% and precision (%RSD) of ?2.65%. The accuracy of the methods was further ascertained by recovery experiments via a standard-addition procedure.

  14. Spectrophotometric estimation of solifenacin succinate in tablet formulations

    PubMed Central

    Singh, Lokesh; Nanda, Sanju

    2011-01-01

    Aim: The aim of this study is to develop a simple, sensitive, rapid, accurate, and precise spectrophotometric method for the estimation of solifenacin succinate in tablet dosage forms. Materials and Methods: For methods I and II, in a series of 10 ml volumetric flasks, aliquots of standard drug solution (100 ?g/ml) in double distilled water were transferred and diluted with the same so as to give several dilutions in the concentration ranges of 10 – 60 ?g/ml and 10 – 60 ?g/ml, respectively, of solifenacin succinate. To 5 ml of each dilution taken in a separating funnel, (5 ml of bromo thymol blue for method I and 5 ml of bromo phenol blue for method II) reagent and 5 ml of chloroform were added. The reaction mixture was shaken gently for five minutes and allowed to stand so as to separate the aqueous and chloroform layers. The absorbance maxima were measured at 415.6 nm and 412 nm for methods I and II, respectively. Results: The recovery studies were found close to 100%, which indicates the accuracy and precision of the proposed methods. Statistical analysis was carried out, the results of which were found to be satisfactory. Standard deviation values were found to be low and that indicated the reproducibility of the proposed methods. Conclusion: The results indicated that both methods could be used for the routine estimation of solifenacin succinate from tablet formulations. PMID:23781425

  15. Spectrophotometric estimation of betahistine hydrochloride in tablet formulations

    PubMed Central

    Kumar, Amit; Nanda, Sanju; Chomwal, Rajiv

    2010-01-01

    Aim: The study aims to develop simple, sensitive, rapid, accurate and precise spectrophotometric method for estimation of Betahistine hydrochloride in tablet dosage forms. Materials and Methods: For method I and II, in a series of 10 ml volumetric flask, aliquots of standard drug solution (100 ?g/ml) in double distilled water were transferred and diluted with same so as to give several dilutions in concentration range of 15-90 ?g/ml and 10-80 ?g/ml respectively of betahistine hydrochloride. To 5 ml of each dilution taken in a separating funnel, (5 ml of methyl orange for method I and 5 ml of bromo phenol blue for method II) reagent and 5 ml of chloroform was added. Reaction mixture was shaken gently for 5 min and allowed to stand so as to separate aqueous and chloroform layer. Absorbance maxima measured at 421.6 nm and 412 nm for method I and II respectively. Results: The recovery studies were found close to 100 % that indicates accuracy and precision of the proposed methods. The statistical analysis was carried out and results of which were found satisfactory. Standard deviation values were found low that indicated reproducibility of the proposed methods. Conclusion: Based on results the developed methods could be used for routine estimation of betahistine hydrochloride from tablet formulations. PMID:21814445

  16. Development of an ion-pair reversed-phase HPLC method with indirect UV detection for determination of phosphates and phosphites as impurities in sodium risedronate.

    PubMed

    Breuzovska, Katerina; Dimitrovska, Aneta; Kitanovski, Zoran; Petrusevska, Jelena; Ribarska, Jasmina Tonic; Jolevska, Suzana Trajkovic

    2010-01-01

    A method based on RP-HPLC with indirect UV detection was developed for the determination of phosphates and phosphites as impurities in sodium risedronate. RP separation of the phosphates and phosphites was achieved by adding tetrabutylammonium hydroxide as an ion-pairing agent in the mobile phase. Potassium hydrogen phthalate was added to the mobile phase as an ionic chromophore in order to obtain high background absorption of the mobile phase. Separation was performed on a C18 column using a mixture of pH 8.2 buffer (containing 0.5 mM tetrabutylammonium hydroxide and 1 mM phthalate) and acetonitrile (95 + 5, v/v) as the mobile phase, with indirect UV detection at 248 nm. The validation of the method included determination of specificity/selectivity, linearity, LOD, LOQ, accuracy, precision, and robustness. The LOD was 0.86 microg/mL for phosphates and 0.76 microg/mL for phosphites. The LOQ was 2.60 microg/mL for phosphates and 2.29 microg/mL for phosphites. The developed method is suitable for quantitative determination of phosphates and phosphites as impurities in QC of sodium risedronate. PMID:20922941

  17. Kinetic spectrophotometric determination of certain cephalosporins using oxidized quercetin reagent

    NASA Astrophysics Data System (ADS)

    Saleh, Gamal A.; El-Shaboury, Salwa R.; Mohamed, Fardous A.; Rageh, Azza H.

    2009-09-01

    A simple, precise and accurate kinetic spectrophotometric method for determination of cefoperazone sodium, cefazolin sodium and ceftriaxone sodium in bulk and in pharmaceutical formulations has been developed. The method is based upon a kinetic investigation of the reaction of the drug with oxidized quercetin reagent at room temperature for a fixed time of 30 min. The decrease in absorbance after the addition of the drug was measured at 510 nm. The absorbance concentration plot was rectilinear over the range 80-400 ?g mL -1 for all studied drugs. The concentration of the studied drugs was calculated using the corresponding calibration equation for the fixed time method. The determination of the studied drugs by initial rate, variable time and rate-constant methods was feasible with the calibration equations obtained but the fixed time method has been found to be more applicable. The analytical performance of the method, in terms of accuracy and precision, was statistically validated; the results were satisfactory. The method has been successfully applied to the determination of the studied drugs in commercial pharmaceutical formulations. Statistical comparison of the results with a well established reported method showed excellent agreement and proved that there is no significant difference in the accuracy and precision.

  18. UV-Vis microspectrophotometry as a method of differentiation between cotton fibre evidence coloured with reactive dyes

    NASA Astrophysics Data System (ADS)

    Was-Gubala, Jolanta; Starczak, Roza

    2015-05-01

    The main purposes of this study was to assess the usefulness of microspectrophotometry (MSP), both in the ultraviolet (UV) and visible (Vis) range for discriminating single cotton fibres dyed with reactive dyes coming from the same manufacturer, as well as the possibility of evaluation of the concentration of dye in an examine fibre. This study utilised woven cotton fabrics dyed with different concentrations of one-compound reactive dyes with the commercial name Cibacron® (at present Novacron®) as the focus of the MSP analysis. The spectra were recorded in the UV-Vis range between 200 and 800 nm, in transmission mode. The results from this study illustrated that all of the analysed cotton samples dyed with reactive dyes were distinguishable between each other with the use of MSP, mostly in the visible, and also in ultraviolet range. The limit for applied MSP techniques was 0.18% of the concentration of a dye in the textile sample. The results indicate that based on the absorbance measurements for fibres constituting e.g. forensic traces it was not possible to estimate the concentration of the dye in the fibre because Beer's law did not obey. The intra-sample, and inter- sample variation, as well as dichroism effect in a case of a cotton fibres dyed with reactive dye were observed. On the basis of the results obtained for each analysed cotton sample, it was concluded that there was no correlation between colour uniformity in cotton fabric (changes in lightness, red/green and yellow/blue colour) and concentration of the reactive dye.

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

    PubMed

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

    2008-06-01

    High-performance liquid chromatography (HPLC)-UV and HPLC-Mass Spectrometry (MS) methods were developed for the quantitative analysis of the family of Hoodia gordonii steroid glycosides with appetite suppressing properties in dried plant material, in purified and enriched extracts and in various prototype food-products fortified with H. gordonii extracts. For solid materials, e.g. dried plants or for non-fatty foods, extraction of the steroid glycosides is performed using methanol. For products where the steroid glycosides are present in an oil matrix, direct injection of the oil after dilution in tetrahydrofuran is applied. The HPLC separation is performed on an octyl-modified reversed-phase column in the gradient mode with UV detection at lambda = 220 nm. Quantification is performed against an external calibration line prepared using either one of the pure steroid glycosides or geranyl-tiglate. Short- and long-term repeatabilities of the methods are better than 3 and 6%, respectively. Recoveries are better than 85%, even in the analysis of the least abundant steroid glycosides in a complex yoghurt drink. Linearity is better than 3-4 orders of magnitude and the detection limits are below approximately 2 microg g(-1) for the individual steroid glycosides in dried plant material and food products. HPLC-MS is used to confirm that the steroid glycosides contain the characteristic steroid core, the carbohydrate chain and the tigloyl group. PMID:18486659

  20. Determination of pterostilbene in rat plasma by a simple HPLC-UV method and its application in pre-clinical pharmacokinetic study.

    PubMed

    Lin, Hai-Shu; Yue, Bing-De; Ho, Paul C

    2009-12-01

    A simple HPLC-UV method was developed and validated for the quantification of pterostilbene (3,5-dimethoxy-4'-hydroxy-trans-stilbene), a pharmacologically active phytoalexin in rat plasma. The assay was carried out by measuring the UV absorbance at 320 nm. Pterostilbene and the internal standard, 3,5,4'-trimethoxy-trans-stilbene eluted at 5.7 and 9.2 min, respectively. The calibration curve (20-2000 ng/mL) was linear (R(2)> 0.997). The lower limits of detection and of quantification were 6.7 and 20 ng/mL, respectively. The intra- and inter-day precisions in terms of RSD were all lower than 6%. The analytical recovery ranged from 95.5 +/- 3.7 to 103.2 +/- 0.7% while the absolute recovery ranged from 101.9 +/- 1.1 to 104.9 +/- 4.4%. This simple HPLC method was subsequently applied in a pharmacokinetic study carried out in Sprague-Dawley rats. The terminal elimination half-life and clearance of pterostilbene were 96.6 +/- 23.7 min and 37.0 +/- 2.5 mL/min/kg, respectively, while its absolute oral bioavailability was 12.5 +/- 4.7%. Pterostilbene appeared to have better pharmacokinetic characteristics than its natural occurring analog, resveratrol. PMID:19488981

  1. Spectrophotometric study of the solvation of N-(2-furoyl)-N-phenylhydroxylamine in organic solutions

    SciTech Connect

    Pilipenko, A.T.; Eremenko, M.V.; Falendysh, N.F.

    1985-08-01

    The solvation of N-(2-furoyl)-N-phenylhydroxylamine in chloroformalcohol, chloroform-DMSO, and chloroform-DMF solutions was studied by the spectrophotometric method. It was shown that, depending on the concentration of the polar solvent, two types of solvates are formed. The compositions and stabilities of the solvates with methanol, ethanol, DMF, and DMSO were determined. The solvents used are those most frequently used for the preparation of solutions in the investigation of complex formation and extraction processes.

  2. Spectrophotometric Assay for Hypochlorite\\/Hypochlorous Acid Using Tris(2-carboxyethyl)phosphine

    Microsoft Academic Search

    Joan Han; Teh-Ching Chu; Grace Han; John Browne; Irene Brown; Peter Han

    1998-01-01

    A simple spectrophotometric method for quantitative determination of hypochlorite (OCl?) or hypochlorous acid (HOCl) is described. The OCl?or HOCl sample is first incubated with an excess amount of tris(2-carboxyethyl)phosphine (TCEP). The concentration of the residual TCEP is then measured as the amount of 2-nitro-5-thiobenzoate produced after reaction with 5,5?-dithiobis(2-nitrobenzoic acid). The concentration of OCl?or HOCl is equivalent to the amount

  3. SolidPhase Extraction and Spectrophotometric Determination of Trace Amounts of Mercury in Natural Samples

    Microsoft Academic Search

    Derya Kara; Nalan Tekin

    2005-01-01

    A sensitive and selective solid phase spectrophotometric method for the determination of trace amounts of inorganic mercury is described. Hg2+ was sorbed on a silica gel-packed column as an Hg2+–N,N'-bis(2-mercaptophenyl)ethanediamide (H2L) complex. The Hg2+ complex was eluted from the column using 7?mL of acetone. Various parameters including pH, column flow rate, and ligand concentration were optimized. The complex was found

  4. Spectrophotometric determination of nickel using a new chromogenic reagent in plant leaves

    Microsoft Academic Search

    K. SURESH KUMAR; B. LOKANATH SWAROOP; S. PRABHAKARA RAO; P. CHIRANJEEVI

    2004-01-01

    A Spectrophotometric method for the determination of nickel in plant leaves with new chromogenic reagent is presented. A new highly sensitive and selective chromogenic reagent dibromo?p?methyl?carboxyazo was synthesized; in 0.25 M phosphoric acid medium, which greatly increases the selectivity. Nickel reacts with DBMCA to form a 1:2 mole?ratio bluish red complex, having a sensitive absorption peak at 625 nm under optimal conditions.

  5. A simple spectrophotometric technique for determination of Irganox 1010 in polymeric samples

    Microsoft Academic Search

    Mir Ali Farajzadeh; Akram Nasserzadeh; Ali Ranji

    2008-01-01

    .  A simple spectrophotometric method is presented for the determination of tetrakis [methylene (3,5-di-tert-butyl-4-hydroxyhyrocinnamate)] methane (Irganox 1010) in polymeric samples. To a solution of Irganox 1010 in acetone is added\\u000a concentrated sodium hydroxide solution and then it is shaken for a short time. The 2-phase system produced in the upper phase\\u000a (acetone) is yellow colored. Absorbance of the colored phase is

  6. Integrity characterization of myoglobin released from poly(?-caprolactone) microspheres using two analytical methods: UV/Vis spectrometry and conductometric bi-enzymatic biosensor.

    PubMed

    Hnaien, M; Ruffin, E; Bordes, C; Marcillat, O; Lagarde, F; Jaffrezic-Renault, N; Briançon, S

    2011-06-01

    Myoglobin (Mb)-loaded poly(?-caprolactone) (PCL) microparticles were prepared by multiple emulsion with solvent extraction/evaporation method under more or less deleterious operating conditions. The protein integrity was monitored using both UV/Vis absorbance ratio method at specific wavelengths and a conductometric bi-enzymatic biosensor based on proteinase K and pronase. Under standard operating conditions, Mb remained in native conformation, while different degrees of protein denaturation were observed by changing the encapsulation conditions. It was shown that solvent elimination under reduced pressure and in a lower extent addition of a higher molecular weight PCL led to protein alteration. In the first case, the loss of protein integrity can be attributed to residual solvent entrapped in particles whose solidification was accelerated. In the second case, denaturation may be explained by an increase in the protein exposure time at water/organic solvent interface due to an increase in organic phase viscosity. PMID:21284956

  7. A comparative study between PCR and PLS in simultaneous spectrophotometric determination of diphenylamine, aniline, and phenol: Effect of wavelength selection

    Microsoft Academic Search

    Bahram Hemmateenejad; Morteza Akhond; Fayezeh Samari

    2007-01-01

    Partial least squares (PLS) and principal component regression (PCR) have received considerable attention in the chemometrics for multicomponent analysis where superiority of one over another is a challenging problem yet. Considering the effect of wavelength selection, a comparison was made between PCR and PLS methods by application those to simultaneous spectrophotometric determination of diphenylamine (DPA), a compound from the third

  8. Spectrophotometric Assay of Mebendazole in Dosage Forms Using Sodium Hypochlorite

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    A simple, selective and sensitive spectrophotometric method is described for the determination of mebendazole (MBD) in bulk drug and dosage forms. The method is based on the reaction of MBD with hypochlorite in the presence of sodium bicarbonate to form the chloro derivative of MBD, followed by the destruction of the excess hypochlorite by nitrite ion. The color was formed by the oxidation of iodide with the chloro derivative of MBD to iodine in the presence of starch and forming the blue colored product, which was measured at 570 nm. The optimum conditions that affect the reaction were ascertained and, under these conditions, a linear relationship was obtained in the concentration range of 1.25-25.0·g/ml MBD. The calculated molar absorptivity and Sandell sensitivity values are 9.56·103 l·mol-1·cm-1 and 0.031 ?g/cm2, respectively. The limits of detection and quantification are 0.11 and 0.33 ?g/ml, respectively. The proposed method was applied successfully to the determination of MBD in bulk drug and dosage forms, and no interference was observed from excipients present in the dosage forms. The reliability of the proposed method was further checked by parallel determination by the reference method and also by recovery studies.

  9. Evaluation of the Esthetic Properties of Developmental Defects of Enamel: A Spectrophotometric Clinical Study

    PubMed Central

    Guerra, Fabrizio; Mazur, Marta; Corridore, Denise; Pasqualotto, Debora; Nardi, Gianna Maria; Ottolenghi, Livia

    2015-01-01

    Objectives. Detailed clinical quantification of optical properties of developmental defect of enamel is possible with spectrophotometric evaluation. Developmental defects of enamel (DDE) are daily encountered in clinical practice. DDE are an alteration in quality and quantity of the enamel, caused by disruption and/or damage to the enamel organ during amelogenesis. Methods. Several clinical indices have been developed to categorize enamel defects based on their nature, appearance, microscopic features, or cause. A sample of 39 permanent teeth presenting DDE on labial surface was examined using the DDE Modified Index and SpectroShade evaluation. The spectrophotometric approach quantifies L* (luminosity), a* (quantity of green-red), and b* (quantity of blue-yellow) of different DDE. Conclusions. SpectroShade evaluation of the optical properties of the enamel defect enhances clinical understanding of severity and extent of the defect and characterizes the enamel alteration in terms of color discrepancy and surface characterization. PMID:25874260

  10. Proceedings of the Workshop on the Spectrophotometric Dating of Stars and Galaxies

    NASA Technical Reports Server (NTRS)

    Hubeny, Ivan; Heap, Sara; Cornett, Robert

    1999-01-01

    In the past decade, we have seen an avalanche of new observational results from space observatories and ground-based observatories. These observations have revealed young globular clusters in the cores of merger galaxies, elliptical galaxies at redshifts up to z=1.5, and starburst galaxies at high redshift. Analyses of the detailed spectra or color- magnitude diagrams of these systems promise to give a new understanding of evolutionary processes and to provide a check on cosmological ages. At the same time, these new spectro-photometric data present new challenges to current methods of spectral analysis and modeling.At the Workshop, we will discuss these new opportunities and challenges on spectro-photometric dating of stars and galaxies.

  11. Complexation equilibria and spectrophotometric determination of thorium(IV) with Lawsone.

    PubMed

    al-Nady, A B; al-Shaibi, Y; Ba-Issa, A; Ariqui, W

    2001-01-01

    The complex equilibria of Th4+ with Lawsone (2-hydroxy-1,4-naphthoquinone, LAS) were studied spectrophotometrically in 40% (v/v) ethanol water at 25 degrees C and an ionic strength of 0.1 M (NaClO4). The absorbance graphs were analysed to demonstrate and characterize the complex forming equilibria. A simple, rapid, selective and sensitive method for the spectrophotometric determination of trace amounts of thorium(IV) is developed. The complex formed at pH 2.1-3.6 (epsilon = 0.27 x 10(4) cm2 mol-1, at lambda = 440 nm) allows the determination of 5.8-32 micrograms/ml thorium. The effect of interferences was studied. PMID:11770165

  12. Spectrophotometric evaluation of optical performances of polarizing technologies for smart window applications

    NASA Astrophysics Data System (ADS)

    Levati, N.; Vitali, L.; Fustinoni, D.; Niro, A.

    2014-11-01

    In recent years, window-integrated solar protection systems are used and studied as a promising energy saving technology, both for cold and hot climates. In particular, smart windows, whose optical proprieties in the solar wavelength range can somehow be controlled, show interesting results, especially in reducing the air conditioning power consumption. With the improvement of nanolithography techniques as well as with the possibility of designing polarization intervals, coupled polarizing films show a good potential as a dynamic and wavelength-selective shading technology. In this paper, UV-Vis-NIR spectrophotometric measurements are carried out on two polarizing technologies, Polaroid crystalline polarizer and Wire Grid broadband polarizer, in single- and double- film layout, to evaluate their optical performances, i.e. spectral transmittance, reflectance and absorptivity. The solar radiation glazing factors, according to the standard UNI EN 410, are calculated. The measured data are also analyzed in detail to emphasize the optical peculiarities of the materials under study that do not stand out from the standard parameters, as well as the specific problems that arise in spectrophotometric evaluations of polarizing films.

  13. Validation of a fast liquid chromatography-UV method for the analysis of drugs used in combined cardiovascular therapy in human plasma.

    PubMed

    Iriarte, Gorka; Gonzalez, Oskar; Ferreirós, Nerea; Maguregui, Miren Itxaso; Alonso, Rosa Maria; Jiménez, Rosa Maria

    2009-10-01

    Ultra-performance liquid chromatography (UPLC) was investigated as a faster alternative to high-performance liquid chromatography (HPLC) for the simultaneous analysis of drugs usually prescribed in cardiovascular therapy. Upon a previously developed and validated solid phase extraction (SPE)-HPLC-photodiode array (PDA)-fluorescence (FLR) method, separation of chlorthalidone (CLTD; diuretic), valsartan and its metabolite (VAL and VAL-M1 respectively; angiotensin II receptor antagonist drugs) and fluvastatin (FLUV; statin) was performed in human plasma using an RP C18 column (50mmx2.1mm, 1.7microm, Waters Acquity UPLC (BEH)) and a tunable UV-vis (TUV) detector. After method transfer, different system variables were modulated to study the evolution of responses of the analytes and the endogenous interferences. The improved method was fully validated and the results were compared with its precursor HPLC method relating to analysis time, efficiency and sensitivity. The studied compounds were separated in less than 8min and the method showed good linearity (20-3000microg/L for chlorthalidone, 110-1100microg/L for valsartan-M1, 67-1900microg/L for valsartan and 48-1100microg/L for fluvastatin), precision and accuracy. The proposed method was found to be reproducible (RSD<10%), accurate (RE<15%), robust and suitable for quantitative analysis of the studied drugs in plasma obtained from patients under combined cardiovascular treatment. PMID:19660995

  14. Simpler spectrophotometric assay of paracetamol in tablets and urine samples

    NASA Astrophysics Data System (ADS)

    Sirajuddin; Khaskheli, Abdul Rauf; Shah, Afzal; Bhanger, Muhammad Iqbal; Niaz, Abdul; Mahesar, Sarfaraz

    2007-11-01

    A very fast, economical and simpler direct spectrophotometric method was investigated for paracetamol (PC) determination in aqueous medium without using any chemical reagents. The method is based on the photo-absorption of the analyte at 243 nm after dissolution in water. The change in structure of PC after addition of water was studied by comparing the corresponding FTIR spectra. Optimization studies were conducted by using a 5 ?g ml -1 standard solution of the analyte. Various parameters studied include, time for stability and measurement of spectra, effect of HCl, NaOH, CH 3COOH and NH 3 for change in absorbance and shift in spectra, interference by some analgesic drugs and some polar solvents and temperature effect. After optimization, Beer's law was obeyed in the range of 0.3-20 ?g ml -1 PC solution with a correlation coefficient of 0.9999 and detection limit of 0.1 ?g ml -1. The newly developed method was successfully applied for PC determination in some locally available tablets and urine samples. The proposed method is very useful for quick analysis of various types of solid and liquid samples containing PC.

  15. Improved spectrophotometric analysis of barium styphnate

    SciTech Connect

    Brown, N E; Blasi, J A

    1983-01-01

    A spectrophotometric procedure to determine the purity of barium styphnate monohydrate based upon the absorbance of the styphnate ion at 326 and 413.3 nm has been developed. The purity is determined by comparing the absorbance of the styphnate ion in barium styphnate and in styphnic acid. Our investigation has shown that the molar absorptivity and lambda maxima of the styphnate ion are quite pH dependent; therefore, the pH is buffered to 6.8 to 7.0 with ammonium acetate. Under these conditions the molar absorptivity is 1.6 x 10/sup 4/ L/mol-cm. Analyses following the procedure in the Navy specification WS13444A using water were found to give low molar absorptivities (1.3 x 10/sup 4/ L/mol-cm) for the styphnic acid calibration resulting in erroneous values for barium styphnate purity.

  16. A novel method for the thermal analysis of GaN/AlGaN back-illuminated high power UV LEDs

    NASA Astrophysics Data System (ADS)

    Kudsieh, N.; Khizar, M.; Raja, M. Y. A.

    2014-04-01

    We report a novel method for the thermal analysis of high-power multi-quantum well GaN/AlGaN UV LEDs of ? ˜ 330 nm. 3D modeling and simulations of chip-on-plate (COP) have been investigated for the packaging of UV LEDs. Steady state thermal analysis of COP packaged devices were carried out using finite element method (FEM). Different heat sinks’ designs such as plate-fins, and pin-fins were modeled to determine device junction temperatures (T j). We also employed thermal resistance circuit (TRC) model to determine the T j considering both conductive and convective methods of heat transfer. Results were in good agreement both for the FEM and TRC models. For the fine plate-fin dense and the less-dense large-fins heat sinks, calculated T j values were ˜37 °C, and ˜46 °C for a corresponding operating power of ˜1.5 W, respectively. On other hand, similar power level junction temperatures of 33 °C and 41 °C were determined respectively for high- and low-density pin-fins heat sinks. Furthermore, thermal flux analysis of these heat sinks was also performed. A comparative study of on-substrate un-packaged and two different (COP) packaged devices was also performed. It was found that our COP based packaged devices are thermally more stable with improved photoluminescence (PL) intensity. As much as around 30% enhancement in the PL intensity of the packaged devices along with a noticeable decrease in the red-shift (about 7 nm) of the spectrum was determined.

  17. In situ determination of dissolved organic carbon in freshwaters using a reagentless UV sensor.

    PubMed

    Sandford, Richard Charles; Bol, Roland; Worsfold, Paul John

    2010-09-01

    Reliable, high temporal and spatial resolution data are essential for enhancing our understanding of aquatic dissolved organic carbon (DOC) biogeochemical cycling. This paper describes a novel UV spectrophotometric sensor for the real time, in situ, high resolution (every 30 s) mapping of DOC in freshwaters. The sensor incorporates high resolution, multi-wavelength spectral acquisition (256 channel photodiode array) and a hybrid linear analysis (HLA) curve fitting algorithm. The portable and reagentless in situ UV sensor has a good linear range (0.5-15 mg C L(-1)) and precision (mean RSD 8.5%, n = 7 standards each measured 5 times) and quantitative recoveries were obtained for spiked river water (93.8 +/- 6.2%, n = 35). The DOC field data were in good agreement with results from a laboratory high temperature combustion method (t test (p = 0.05) gave P = 0.20 (n = 14), 0.89 (n = 21) and 0.92 (n = 15) for three separate freshwater deployments). These data suggested that solar radiation, coupled with microbial uptake and release, together with the physico-chemical parameters of hydrological flow, temperature and pH were significant drivers of DOC cycling in this ecosystem. Real time data processing provided an immediate data stream for mapping diurnal and/or seasonal DOC cycling. This capability will enhance our understanding of DOC sources, delivery mechanisms and internal cycling and support sustainable catchment management. PMID:20652205

  18. Utility of N-Bromosuccinimide for the Titrimetric and Spectrophotometric Determination of Famotidine in Pharmaceutical Formulations

    PubMed Central

    Zenita, O.; Basavaiah, K.

    2011-01-01

    Two titrimetric and two spectrophotometric methods are described for the assay of famotidine (FMT) in tablets using N-bromosuccinimide (NBS). The first titrimetric method is direct in which FMT is titrated directly with NBS in HCl medium using methyl orange as indicator (method A). The remaining three methods are indirect in which the unreacted NBS is determined after the complete reaction between FMT and NBS by iodometric back titration (method B) or by reacting with a fixed amount of either indigo carmine (method C) or neutral red (method D). The method A and method B are applicable over the range of 2–9?mg and 1–7?mg, respectively. In spectrophotometric methods, Beer's law is obeyed over the concentration ranges of 0.75–6.0??g?mL?1 (method C) and 0.3–3.0??g?mL?1 (method D). The applicability of the developed methods was demonstrated by the determination of FMT in pure drug as well as in tablets. PMID:21760785

  19. Validation Thin Layer Chromatography for the Determination of Acetaminophen in Tablets and Comparison with a Pharmacopeial Method

    PubMed Central

    Pyka, Alina; Budzisz, Marika; Do?owy, Ma?gorzata

    2013-01-01

    Adsorption thin layer chromatography (NP-TLC) with densitometry has been established for the identification and the quantification of acetaminophen in three leading commercial products of pharmaceutical tablets coded as brand: P1 (Product no. 1), P2 (Product no. 2), and P3 (Product no. 3). Applied chromatographic conditions have separated acetaminophen from its related substances, namely, 4-aminophenol and and 4?-chloroacetanilide. UV densitometry was performed in absorbance mode at 248?nm. The presented method was validated by specificity, range, linearity, accuracy, precision, detection limit, quantitative limit, and robustness. The TLC-densitometric method was also compared with a pharmacopeial UV-spectrophotometric method for the assay of acetaminophen, and the results confirmed statistically that the NP-TLC-densitometric method can be used as a substitute method. It could be said that the validated NP-TLC-densitometric method is suitable for the routine analysis of acetaminophen in quantity control laboratories. PMID:24063006

  20. Accurate electronic and chemical properties of 3d transition metal oxides using a calculated linear response U and a DFT + U(V) method.

    PubMed

    Xu, Zhongnan; Joshi, Yogesh V; Raman, Sumathy; Kitchin, John R

    2015-04-14

    We validate the usage of the calculated, linear response Hubbard U for evaluating accurate electronic and chemical properties of bulk 3d transition metal oxides. We find calculated values of U lead to improved band gaps. For the evaluation of accurate reaction energies, we first identify and eliminate contributions to the reaction energies of bulk systems due only to changes in U and construct a thermodynamic cycle that references the total energies of unique U systems to a common point using a DFT + U(V) method, which we recast from a recently introduced DFT + U(R) method for molecular systems. We then introduce a semi-empirical method based on weighted DFT/DFT + U cohesive energies to calculate bulk oxidation energies of transition metal oxides using density functional theory and linear response calculated U values. We validate this method by calculating 14 reactions energies involving V, Cr, Mn, Fe, and Co oxides. We find up to an 85% reduction of the mean average error (MAE) compared to energies calculated with the Perdew-Burke-Ernzerhof functional. When our method is compared with DFT + U with empirically derived U values and the HSE06 hybrid functional, we find up to 65% and 39% reductions in the MAE, respectively. PMID:25877590

  1. Accurate electronic and chemical properties of 3d transition metal oxides using a calculated linear response U and a DFT + U(V) method

    NASA Astrophysics Data System (ADS)

    Xu, Zhongnan; Joshi, Yogesh V.; Raman, Sumathy; Kitchin, John R.

    2015-04-01

    We validate the usage of the calculated, linear response Hubbard U for evaluating accurate electronic and chemical properties of bulk 3d transition metal oxides. We find calculated values of U lead to improved band gaps. For the evaluation of accurate reaction energies, we first identify and eliminate contributions to the reaction energies of bulk systems due only to changes in U and construct a thermodynamic cycle that references the total energies of unique U systems to a common point using a DFT + U(V ) method, which we recast from a recently introduced DFT + U(R) method for molecular systems. We then introduce a semi-empirical method based on weighted DFT/DFT + U cohesive energies to calculate bulk oxidation energies of transition metal oxides using density functional theory and linear response calculated U values. We validate this method by calculating 14 reactions energies involving V, Cr, Mn, Fe, and Co oxides. We find up to an 85% reduction of the mean average error (MAE) compared to energies calculated with the Perdew-Burke-Ernzerhof functional. When our method is compared with DFT + U with empirically derived U values and the HSE06 hybrid functional, we find up to 65% and 39% reductions in the MAE, respectively.

  2. A fast tree-based method for estimating column densities in adaptive mesh refinement codes. Influence of UV radiation field on the structure of molecular clouds

    NASA Astrophysics Data System (ADS)

    Valdivia, Valeska; Hennebelle, Patrick

    2014-11-01

    Context. Ultraviolet radiation plays a crucial role in molecular clouds. Radiation and matter are tightly coupled and their interplay influences the physical and chemical properties of gas. In particular, modeling the radiation propagation requires calculating column densities, which can be numerically expensive in high-resolution multidimensional simulations. Aims: Developing fast methods for estimating column densities is mandatory if we are interested in the dynamical influence of the radiative transfer. In particular, we focus on the effect of the UV screening on the dynamics and on the statistical properties of molecular clouds. Methods: We have developed a tree-based method for a fast estimate of column densities, implemented in the adaptive mesh refinement code RAMSES. We performed numerical simulations using this method in order to analyze the influence of the screening on the clump formation. Results: We find that the accuracy for the extinction of the tree-based method is better than 10%, while the relative error for the column density can be much more. We describe the implementation of a method based on precalculating the geometrical terms that noticeably reduces the calculation time. To study the influence of the screening on the statistical properties of molecular clouds we present the probability distribution function of gas and the associated temperature per density bin and the mass spectra for different density thresholds. Conclusions: The tree-based method is fast and accurate enough to be used during numerical simulations since no communication is needed between CPUs when using a fully threaded tree. It is then suitable to parallel computing. We show that the screening for far UV radiation mainly affects the dense gas, thereby favoring low temperatures and affecting the fragmentation. We show that when we include the screening, more structures are formed with higher densities in comparison to the case that does not include this effect. We interpret this as the result of the shielding effect of dust, which protects the interiors of clumps from the incoming radiation, thus diminishing the temperature and changing locally the Jeans mass.

  3. Males do not see only red: UV wavelengths and male territorial aggression in the three-spined stickleback ( Gasterosteus aculeatus)

    NASA Astrophysics Data System (ADS)

    Rick, Ingolf P.; Bakker, Theo C. M.

    2008-07-01

    Animal colour signals serve important functions in intraspecific interactions, including species recognition, mate choice and agonistic behaviour. An increasing interest concerns ultraviolet (UV) wavelengths, for instance studies on the effect of UV in mating decisions. More recently, some studies also established that UV signals affect intrasexual interactions. We studied the role of UV during aggressive encounters between male three-spined sticklebacks ( Gasterosteus aculeatus), a species in which UV has an effect on female and male mate choice and shoaling behaviour. To that aim, we compared the aggressive response of a territorial male to male intruders, either seen in UV-including (UV+) or UV-lacking (UV-) conditions. Our prediction was that, if UV wavelengths are used in male-male competition, a territorial male should show less competitive behaviour towards an intruder representing a lower threat, i.e. the one presented without UV light. Male sticklebacks showed significantly lower levels of aggression towards male opponents lacking an UV component to their coloration than male opponents possessing this colour component. Discrimination was not influenced by a difference in brightness between the UV+ and UV- stimuli. Finally, we present some reflectance-spectrophotometrical data of two skin regions (cheek and abdomen) of the experimental males and analysed relationships between colorimetric variables, body variables and behaviour. Our study emphasises that UV visual cues are of importance in different communicational tasks in the three-spined stickleback.

  4. Determination of cefadroxil by sequential injection with spectrophotometric detector.

    PubMed

    Makchit, Jirayu; Upalee, Suphachock; Thongpoon, Chalermporn; Liawruangrath, Boonsom; Liawruangrath, Saisunee

    2006-04-01

    A sequential injection analysis (SIA) spectrophotometric procedure for cefadroxil determination has been developed. The SIA instrumentation was modified to achieve the desired function and operations by using the software developed to interface the PC with the conventional SIA system. The method is based on the measurement of a red, water-soluble product formed by the reaction between cefadroxil and 4-aminoantipyrine in the presence of alkaline potassium hexacyanoferrate(III) at 510 nm. Optimum conditions for determining the drug were investigated. Beer's law was obeyed over the concentration ranges of 1 - 10 mg L(-1) and 10 - 50 mg L(-1) with a detection limit (3 sigma) of 0.17 mg L(-1) and a limit of quantification (10 sigma) of 0.56 mg L(-1). The relative standard deviations of 1.98% and 1.93% for 5 mg L(-1) and 30 mg L(-1) of the drug, respectively (n = 11) are obtained. The proposed method has been applied satisfactorily to the determination of cefadroxil in commercial pharmaceutical formulations with a sampling rate of 100 h(-1). Results obtained were in good agreement with those obtained by the official HPLC method at the 95% confidence level. PMID:16760604

  5. Spectrophotometric determination of paracetamol with microwave assisted alkaline hydrolysis

    NASA Astrophysics Data System (ADS)

    Xu, Chunli; Li, Baoxin

    2004-07-01

    A novel and rapid spectrophotometric method for the determination of paracetamol is proposed in this paper. The proposed method is based on the microwave assisted alkaline hydrolysis of paracetamol to p-aminophenol that reacts with S 2- in the presence of Fe 3+ as oxidant to produce a methylene blue-like dye having an absorptivity maximum at 540 nm. The experiment showed that paracetamol could be hydrolysed quantitatively to p-aminophenol in only 1.5 min under radiation power 640 W using a microwave in NaOH medium. The system obeys Beer's law in the range of 0-3.0×10 -4 mol l -1 paracetamol. The molar absorptivity and Sandell's sensitivity were found to be 3.2×10 3 l mol -1 cm -1 and 0.047 ?g cm -2, respectively. The relative standard deviation ( n=11) was 1.7% for 8.0×10 -5 mol l -1 paracetamol. The method has been applied successfully to analysis of paracetamol in pharmaceutical preparation.

  6. LC-UV/MS methods for the analysis of prochelator-boronyl salicylaldehyde isonicotinoyl hydrazone (BSIH) and its active chelator salicylaldehyde isonicotinoyl hydrazone (SIH).

    PubMed

    Bureš, Jan; Jansová, Hana; Stariat, Ján; Filipský, Tomáš; Mlad?nka, P?emysl; Šim?nek, Tomáš; Ku?era, Radim; Klimeš, Ji?í; Wang, Qin; Franz, Katherine J; Kova?íková, Petra

    2015-02-01

    Salicylaldehyde isonicotinoyl hydrazone (SIH) is an intracellular iron chelator with well documented potential to protect against oxidative injury both in vitro and in vivo. However, it suffers from short biological half-life caused by fast hydrolysis of the hydrazone bond. Recently, a concept of boronate prochelators has been introduced as a strategy that might overcome these limitations. This study presents two complementary analytical methods for detecting the prochelator-boronyl salicylaldehyde isonicotinoyl hydrazone-BSIH along with its active metal-binding chelator SIH in different solution matrices and concentration ranges. An LC-UV method for determination of BSIH and SIH in buffer and cell culture medium was validated over concentrations of 7-115 and 4-115 ?M, respectively, and applied to BSIH activation experiments in vitro. An LC-MS assay was validated for quantification of BSIH and SIH in plasma over the concentration range of 0.06-23 and 0.24-23 ?M, respectively, and applied to stability studies in plasma in vitro as well as analysis of plasma taken after i.v. administration of BSIH to rats. A Zorbax-RP bonus column and mobile phases containing either phosphate buffer with EDTA or ammonium formate and methanol/acetonitrile mixture provided suitable conditions for the LC-UV and LC-MS analysis, respectively. Samples were diluted or precipitated with methanol prior to analysis. These separative analytical techniques establish the first validated protocols to investigate BSIH activation by hydrogen peroxide in multiple matrices, directly compare the stabilities of the prochelator and its chelator in plasma, and provide the first basic pharmacokinetic data of this prochelator. Experiments reveal that BSIH is stable in all media tested and is partially converted to SIH by H2O2. The observed integrity of BSIH in plasma samples from the in vivo study suggests that the concept of prochelation might be a promising strategy for further development of aroylhydrazone cytoprotective agents. PMID:25527982

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

    Microsoft Academic Search

    A. Zalacain; S. A. Ordoudi; I. Blázquez; E. M. Díaz-Plaza; M. Carmona; M. Z. Tsimidou; G. L. Alonso

    2005-01-01

    A screening method for the detection of artificial colours (naphthol yellow, tartrazine, quinoline yellow, Sunset yellow, Allura red, amaranth, azorubine, Ponceau 4R and Red 2G) in saffron is described. The method involves removal of crocins by precipitation of crocetin (pH 0.1, 90°C) before adsorption of the artificial colours on polyamide SPE cartridges (pH 2). After washing with methanol, acetone and

  8. Spectrophotometric and spectrofluorimetric determination of etodolac and aceclofenac.

    PubMed

    El Kousy, N M

    1999-06-01

    Two simple, sensitive and reproducible spectrophotometric and spectrofluorimetric methods were adopted for the analysis of the anti-inflammatory drugs, etodolac and aceclofenac. The first method is based on the formation of coloured complexes between the drugs and p-dimethylaminobenzaldehyde reagent (PDAB) in the presence of sulfuric acid and ferric chloride. Measurement of the absorbances was carried out at 591.5 and 545.5 nm for etodolac and aceclofenac, respectively. Regression analysis of Beer's plots showed good correlation in the concentration ranges 10-80 and 8-55 microg ml(-1), respectively. The second was the spectrofluorimetric method in which samples of etodolac in ethanol showed native fluorescence at a lambda = 345 nm when excitation was at 235 nm and samples of aceclofenac in the phosphate buffer pH 8 showed native fluorescence at lambda = 355 nm when excitation was at 250 nm. The calibration graph was rectilinear from 96 to 640 ng ml(-1) for etodolac and from 2 to 8 microg ml(-1) for aceclofenac. The proposed methods are applied successfully for the determination of the two drugs in bulk powder with a mean accuracy of 100.48+/-0.85 and 100.03+/-0.38 in the PDAB method and of 100.61+/-0.79 and 99.88+/-0.45 in the spectrofluorimetric method. Applicability of the proposed methods was examined by analysing dosage forms of the investigated drugs. Recoveries were 98.77-101.46 and 98.65-102.10% for the two methods, respectively and RSD values were 0.6-0.7 and 0.35-1.06% respectively. PMID:10704022

  9. Spectrophotometric determination of sildenafil citrate in pure form and in pharmaceutical formulation using some chromotropic acid azo dyes

    Microsoft Academic Search

    Y. M. Issa; W. F. El-Hawary; A. F. A. Youssef; A. R. Senosy

    2010-01-01

    Two simple and highly sensitive spectrophotometric methods were developed for the quantitative determination of the drug sildenafil citrate (SC), Viagra, in pure form and in pharmaceutical formulations, through ion-associate formation reactions (method A) with mono-chromotropic acid azo dyes, chromotrope 2B (I) and chromotrope 2R (II) and ion-pair reactions (method B) with bi-chromotropic acid azo dyes, 3-phenylazo-6-o-carboxyphenylazo-chromotropic acid (III), bis-3,6-(o-hydroxyphenylazo)-chromotropic acid

  10. Sensitive flow-injection spectrophotometric analysis of bromopride.

    PubMed

    Lima, Liliane Spazzapam; Los Weinert, Patrícia; Pezza, Leonardo; Pezza, Helena Redigolo

    2014-12-10

    A flow injection spectrophotometric procedure employing merging zones is proposed for direct bromopride determination in pharmaceutical formulations and biological fluids. The proposed method is based on the reaction between bromopride and p-dimethylaminocinnamaldehyde (p-DAC) in acid medium, in the presence of sodium dodecyl sulfate (SDS), resulting in formation of a violet product (?max=565nm). Experimental design methodologies were used to optimize the experimental conditions. The Beer-Lambert law was obeyed in a bromopride concentration range of 3.63×10(-7) to 2.90×10(-5)molL(-1), with a correlation coefficient (r) of 0.9999. The limits of detection and quantification were 1.07×10(-7) and 3.57×10(-7)molL(-1), respectively. The proposed method was successfully applied to the determination of bromopride in pharmaceuticals and human urine, and recoveries of the drug from these media were in the ranges 99.6-101.2% and 98.6-102.1%, respectively. This new flow injection procedure does not require any sample pretreatment steps. PMID:24992919

  11. Sensitive flow-injection spectrophotometric analysis of bromopride

    NASA Astrophysics Data System (ADS)

    Lima, Liliane Spazzapam; Weinert, Patrícia Los; Pezza, Leonardo; Pezza, Helena Redigolo

    2014-12-01

    A flow injection spectrophotometric procedure employing merging zones is proposed for direct bromopride determination in pharmaceutical formulations and biological fluids. The proposed method is based on the reaction between bromopride and p-dimethylaminocinnamaldehyde (p-DAC) in acid medium, in the presence of sodium dodecyl sulfate (SDS), resulting in formation of a violet product (?max = 565 nm). Experimental design methodologies were used to optimize the experimental conditions. The Beer-Lambert law was obeyed in a bromopride concentration range of 3.63 × 10-7 to 2.90 × 10-5 mol L-1, with a correlation coefficient (r) of 0.9999. The limits of detection and quantification were 1.07 × 10-7 and 3.57 × 10-7 mol L-1, respectively. The proposed method was successfully applied to the determination of bromopride in pharmaceuticals and human urine, and recoveries of the drug from these media were in the ranges 99.6-101.2% and 98.6-102.1%, respectively. This new flow injection procedure does not require any sample pretreatment steps.

  12. A GALACTIC WEIGH-IN: MASS MODELS OF SINGS GALAXIES USING CHEMO-SPECTROPHOTOMETRIC GALACTIC EVOLUTION MODELS

    SciTech Connect

    De Denus-Baillargeon, M.-M.; Hernandez, O.; Carignan, C. [Laboratoire d'Astrophysique Experimentale, Departement de Physique, Universite de Montreal, C.P. 6128, Succursale Centre-ville, Montreal, QC H3C 3J7 (Canada); Boissier, S.; Amram, P. [LAM (Laboratoire d'Astrophysique de Marseille), Universite Aix-Marseille, CNRS, UMR 7326, F-13388 Marseille (France)

    2013-08-20

    The baryonic mass-to-light ratio (Y{sub *}) used to perform the photometry-to-mass conversion has a tremendous influence on the measurement of the baryonic content and distribution as well as on the determination of the dark halo parameters. Since numerous clues hint at an inside-out formation process for galaxies, a radius-dependant Y{sub *} is needed to physically represent the radially varying stellar population. In this article, we use chemo-spectrophotometric galactic evolution (CSPE) models to determine Y{sub *} for a wide range of masses and sizes in the scenario of an inside-out formation process by gas accretion. We apply our method to a SINGS subsample of 10 spiral and dwarf galaxies with photometric coverage ranging from the UV to the mid-IR. The CSPE models prove to be a good tool for weighting the different photometric bands in order to obtain consistent stellar disk masses regardless of the spectral band used. On the other hand, we show that the color index versus Y{sub *} relation is an imperfect tool for assigning masses to young stellar populations because of the degeneracy affecting Y{sub *} in all bands at low color index. The disks resulting from our analysis are compatible with the maximum disk hypothesis provided that an adequate bulge/disk decomposition is performed and that the correction for the presence of a bar is not neglected since bars disturb the internal disk kinematics. Disk-mass models including Y{sub *} as a free parameter as well as models using our physically motivated, radially varying Y{sub *} are presented and discussed for each galaxy.

  13. Two different spectrophotometric determinations of potential anticancer drug and its toxic metabolite

    NASA Astrophysics Data System (ADS)

    Farid, Nehal F.; Abdelwahab, Nada S.

    2015-06-01

    Flutamide is a hormone therapy used for men with advanced prostate cancer. Flutamide is highly susceptible to hydrolysis with the production of 3-(trifluoromethyl)aniline, which is reported to be one of its toxic metabolites, impurities and related substances according to BP and USP. Flutamide was found to be stable when exposed to oxidation by 30% hydrogen peroxide and direct sunlight for up to 4 h. Two accurate and sensitive spectrophotometric methods were used for determination of flutamide in bulk and in pharmaceutical formulations. Method (I) is the area under curve (AUC) spectrophotometric method that depends on measuring the AUC in the wavelength ranges of 275-305 nm and 350-380 nm and using Cramer's rule. The linearity range was found to be 1-35 ?g/mL and 0.5-16 ?g/mL for the drug and the degradate, respectively. In method (II), combination of the isoabsorptive and dual wavelength spectrophotometric methods was used for resolving the binary mixture. The absorbance at 249.2 nm (?iso) was used for determination of total mixture concentration, while the difference in absorbance between 232 nm and 341.2 nm was used for measuring the drug concentration. By subtraction, the degradate concentration was obtained. Beer's law was obeyed in the range of 2-35 ?g/mL and 0.5-20 ?g/mL for the drug and its degradate, respectively. The two methods were validated according to USP guidelines and were applied for determination of the drug in its pharmaceutical dosage form. Moreover AUC method was used for the kinetic study of the hydrolytic degradation of flutamide. The kinetic degradation of flutamide was found to follow pseudo-first order kinetics and is pH and temperature dependent. Activation energy, kinetic rate constants and t1/2 at different temperatures and pH values were calculated.

  14. Two different spectrophotometric determinations of potential anticancer drug and its toxic metabolite.

    PubMed

    Farid, Nehal F; Abdelwahab, Nada S

    2015-06-15

    Flutamide is a hormone therapy used for men with advanced prostate cancer. Flutamide is highly susceptible to hydrolysis with the production of 3-(trifluoromethyl)aniline, which is reported to be one of its toxic metabolites, impurities and related substances according to BP and USP. Flutamide was found to be stable when exposed to oxidation by 30% hydrogen peroxide and direct sunlight for up to 4h. Two accurate and sensitive spectrophotometric methods were used for determination of flutamide in bulk and in pharmaceutical formulations. Method (I) is the area under curve (AUC) spectrophotometric method that depends on measuring the AUC in the wavelength ranges of 275-305nm and 350-380nm and using Cramer's rule. The linearity range was found to be 1-35?g/mL and 0.5-16?g/mL for the drug and the degradate, respectively. In method (II), combination of the isoabsorptive and dual wavelength spectrophotometric methods was used for resolving the binary mixture. The absorbance at 249.2nm (?iso) was used for determination of total mixture concentration, while the difference in absorbance between 232nm and 341.2nm was used for measuring the drug concentration. By subtraction, the degradate concentration was obtained. Beer's law was obeyed in the range of 2-35?g/mL and 0.5-20?g/mL for the drug and its degradate, respectively. The two methods were validated according to USP guidelines and were applied for determination of the drug in its pharmaceutical dosage form. Moreover AUC method was used for the kinetic study of the hydrolytic degradation of flutamide. The kinetic degradation of flutamide was found to follow pseudo-first order kinetics and is pH and temperature dependent. Activation energy, kinetic rate constants and t1/2 at different temperatures and pH values were calculated. PMID:25795610

  15. Simultaneous spectrophotometric determination of pseudoephedrine hydrochloride and ibuprofen in a pharmaceutical preparation using ratio spectra derivative spectrophotometry and multivariate calibration techniques

    Microsoft Academic Search

    ?. Murat Palabiyik; Erdal Dinç; Feyyaz Onur

    2004-01-01

    Spectrophotometric methods are described for the simultaneous determination of pseudoephedrine hydrochloride and ibuprofen in their combination. The obtained data were evaluated by using five different methods. In the first method, ratio spectra derivative spectrophotometry, analytical signals were measured at the wavelengths corresponding to either maximums and minimums for both drugs in the first derivative spectra of the ratio spectra obtained

  16. Simultaneous determination of the antipsychotic drugs levomepromazine and clozapine and their main metabolites in human plasma by a HPLC-UV method with solid-phase extraction.

    PubMed

    Mercolini, Laura; Bugamelli, Francesca; Kenndler, Ernst; Boncompagni, Giancarlo; Franchini, Livia; Raggi, Maria Augusta

    2007-02-01

    A HPLC method with UV detection has been developed for the simultaneous determination of levomepromazine, clozapine and their main metabolites: N-desmethyl-levomepromazine, levomepromazine sulphoxide, O-desmethyl-levomepromazine, N-desmethylclozapine and clozapine N-oxide. The analytes were separated on a C8 reversed-phase column using a mobile phase composed of acetonitrile and a pH 2.0, 34 mM phosphate buffer containing 0.3% triethylamine (29:71, v/v). Loxapine was used as the internal standard. A reliable biological sample pre-treatment procedure by means of solid-phase extraction on C1 cartridges was implemented, which allows to obtain good extraction yields (>91%) for all analytes and appropriate sample purification from endogenous interference. The method was validated in terms of extraction yield, precision and accuracy. These assays gave RSD% values for precision always lower than 4.9% and mean accuracy values higher than 92%. The method is suitable for the therapeutic drug monitoring (TDM) of patients undergoing polypharmacy with levomepromazine and clozapine. PMID:17045854

  17. Drug monitoring: simultaneous analysis of lamotrigine, oxcarbazepine, 10-hydroxycarbazepine, and zonisamide by HPLC-UV and a rapid GC method using a nitrogen-phosphorus detector for levetiracetam.

    PubMed

    Greiner-Sosanko, Elizabeth; Giannoutsos, Spiros; Lower, Darla R; Virji, Mohamed A; Krasowski, Matthew D

    2007-10-01

    A high-performance liquid chromatography (HPLC) assay using UV detection is described for the simultaneous measurement of the newer generation anti-epileptic medications lamotrigine, oxcarbazepine (parent drug and active metabolite 10- hydroxycarbazepine), and zonisamide. Detection of all four compounds can be done at 230 nm; however, there is a potential interference with zonisamide in patients on clonazepam therapy. Therefore, the method uses dual wavelength detection: 230 nm for oxcarbazepine and 10-hydroxycarbazepine and 270 nm for lamotrigine and zonisamide. In addition, a simple gas chromatography method using a nitrogen-phosphorus detector is described for the measurement of levetiracetam, another of the recently approved anti-epileptic medications. For both methods, limits of quantitation, linearities, accuracies, and imprecisions cover the therapeutic range for drug monitoring of patients. A wide variety of clinical drugs, including other anti-epileptic drugs, do not interfere with these assays. These procedures would be of special interest to clinical laboratories, particularly due to the limited availability of immunoassays for newer generation anti-epileptic medications and that therapeutic uses of these drugs are expanding beyond epilepsy to other neurologic and psychiatric disorders. PMID:17988451

  18. Validation, transfer and measurement uncertainty estimation of an HPLC-UV method for the quantification of artemisinin in hydro alcoholic extracts of Artemisia annua L.

    PubMed

    Diawara, Hermine Zime; Gbaguidi, Fernand; Evrard, Brigitte; Leclercq, Joëlle Quetin; Moudachirou, Mansourou; Debrus, Benjamin; Hubert, Philippe; Rozet, Eric

    2011-08-25

    Malaria is the world's most important parasitic infection with 500 millions cases annually and almost 2 millions death per year. This disease is more present in Sub-Saharan Africa where 90% of the infections are found. Artemisinin and its semi synthetic derivatives (artemether, artesunate) have actually the most powerful activity on malaria, even in its complicated forms and resistance cases. Various methods have been proposed for detection and quantification of artemisinin in Artemisia annua L. by HPLC-UV, but the plant extracts used for this quantification were extracts obtained with organic solvents (toluene, petroleum ether, hexane). To be able to use crude A. annua extracts prepared at low cost to formulate antipaludic drugs, we chose the use of a mixture of water and ethanol as solvent of extraction, but no adequate analytical method for this kind of extracts is published. The main objectives of this work were first to develop an analytical method for artemisinin quantification in hydro alcoholic extracts of A. annua. Second, this method had to be thoroughly validated by the research and development laboratory and, third, the transfer of this method to the routine laboratory had to be demonstrated. The final aim was to compare the estimation of measurement uncertainty obtained during the method validation with validation standards to measurement uncertainty estimates obtained during the method transfer study with real samples. The method was validated following the accuracy profile methodology and was found to be accurate in the concentration range of 10.0-54.0 ?g/ml with CV<8%. Limit of detection and of quantification were 2.73 and 10.0 ?g/ml, respectively. The method was then successfully transferred to a laboratory in Benin by showing that the quality of the results that it will generate during routine application of the method is sufficient. Finally, the measurement uncertainty of the method was estimated from the validation experiments as well as from the transfer study with authentic unspiked samples of A. annua. The comparison of these measurement uncertainty estimations showed that they were coherent. It confirmed thus that the estimation of measurement uncertainty from validation experiments predicts well the measurement uncertainty of real routine samples. This analytical method was thus shown to be convenient for routine analysis of hydro alcoholic extracts of A. annua in Benin. PMID:21570794

  19. Chemometrics-assisted spectrophotometric method for simultaneous determination of Pb²? and Cu²? ions in different foodstuffs, soil and water samples using 2-benzylspiro [isoindoline-1,5'-oxazolidine]-2',3,4'-trione using continuous wavelet transformation and partial least squares - calculation of pKf of complexes with rank annihilation factor analysis.

    PubMed

    Abbasi Tarighat, Maryam; Nabavi, Masoume; Mohammadizadeh, Mohammad Reza

    2015-06-15

    A new multi-component analysis method based on zero-crossing point-continuous wavelet transformation (CWT) was developed for simultaneous spectrophotometric determination of Cu(2+) and Pb(2+) ions based on the complex formation with 2-benzyl espiro[isoindoline-1,5 oxasolidine]-2,3,4 trione (BSIIOT). The absorption spectra were evaluated with respect to synthetic ligand concentration, time of complexation and pH. Therefore according the absorbance values, 0.015 mmol L(-1) BSIIOT, 10 min after mixing and pH 8.0 were used as optimum values. The complex formation between BSIIOT ligand and the cations Cu(2+) and Pb(2+) by application of rank annihilation factor analysis (RAFA) were investigated. Daubechies-4 (db4), discrete Meyer (dmey), Morlet (morl) and Symlet-8 (sym8) continuous wavelet transforms for signal treatments were found to be suitable among the wavelet families. The applicability of new synthetic ligand and selected mother wavelets were used for the simultaneous determination of strongly overlapped spectra of species without using any pre-chemical treatment. Therefore, CWT signals together with zero crossing technique were directly applied to the overlapping absorption spectra of Cu(2+) and Pb(2+). The calibration graphs for estimation of Pb(2+) and Cu (2+)were obtained by measuring the CWT amplitudes at zero crossing points for Cu(2+) and Pb(2+) at the wavelet domain, respectively. The proposed method was validated by simultaneous determination of Cu(2+) and Pb(2+) ions in red beans, walnut, rice, tea and soil samples. The obtained results of samples with proposed method have been compared with those predicted by partial least squares (PLS) and flame atomic absorption spectrophotometry (FAAS). PMID:25766479

  20. Chemometrics-assisted spectrophotometric method for simultaneous determination of Pb2+ and Cu2+ ions in different foodstuffs, soil and water samples using 2-benzylspiro [isoindoline-1,5?-oxazolidine]-2?,3,4?-trione using continuous wavelet transformation and partial least squares - Calculation of pKf of complexes with rank annihilation factor analysis

    NASA Astrophysics Data System (ADS)

    Abbasi Tarighat, Maryam; Nabavi, Masoume; Mohammadizadeh, Mohammad Reza

    2015-06-01

    A new multi-component analysis method based on zero-crossing point-continuous wavelet transformation (CWT) was developed for simultaneous spectrophotometric determination of Cu2+ and Pb2+ ions based on the complex formation with 2-benzyl espiro[isoindoline-1,5oxasolidine]-2,3,4 trione (BSIIOT). The absorption spectra were evaluated with respect to synthetic ligand concentration, time of complexation and pH. Therefore according the absorbance values, 0.015 mmol L-1 BSIIOT, 10 min after mixing and pH 8.0 were used as optimum values. The complex formation between BSIIOT ligand and the cations Cu2+ and Pb2+ by application of rank annihilation factor analysis (RAFA) were investigated. Daubechies-4 (db4), discrete Meyer (dmey), Morlet (morl) and Symlet-8 (sym8) continuous wavelet transforms for signal treatments were found to be suitable among the wavelet families. The applicability of new synthetic ligand and selected mother wavelets were used for the simultaneous determination of strongly overlapped spectra of species without using any pre-chemical treatment. Therefore, CWT signals together with zero crossing technique were directly applied to the overlapping absorption spectra of Cu2+ and Pb2+. The calibration graphs for estimation of Pb2+ and Cu 2+were obtained by measuring the CWT amplitudes at zero crossing points for Cu2+ and Pb2+ at the wavelet domain, respectively. The proposed method was validated by simultaneous determination of Cu2+ and Pb2+ ions in red beans, walnut, rice, tea and soil samples. The obtained results of samples with proposed method have been compared with those predicted by partial least squares (PLS) and flame atomic absorption spectrophotometry (FAAS).

  1. A validated RP-HPLC-UV method for quantitative determination of puerarin in Pueraria tuberosa DC tuber extract

    PubMed Central

    Maji, Amal K.; Maity, Niladri; Banerji, Pratim; Banerjee, Debdulal

    2012-01-01

    Background: Pueraria tuberosa (Fabaceae) is a well-known medicinal herbs used in Indian traditional medicines. The puerarin is one of the most important bioactive constituent found in the tubers of this plant. Quantitative estimation of bioactive molecules is essential for the purpose of quality control and dose determination of herbal medicines. The study was designed to develop a validated reversed phase high-performance liquid chromatography (RP-HPLC) method for the quantification of puerarin in the tuber extract of P. tuberosa. Materials and Methods: The RP-HPLC system with Luna C18 (2) 100 Å, 250 × 4.6 mm column was used in this study. The analysis was performed using the mobile phase: 0.1% acetic acid in acetonitrile and 0.1% acetic acid in water (90:10, v/v) under column temperature 25°C. The detection wavelength was set at 254 nm with a flow rate of 1 ml/min. The method validation was performed according to the guidelines of International Conference on Harmonization. Results: The puerarin content of P. tuberosa extract was found to be 9.28 ±0.09%. The calibration curve showed good linearity relationship in the range of 200-1000?g/ml (r2>0.99). The LOD and LOQ were 57.12 and 181.26?g/ml, respectively and the average recovery of puerarin was 99.73% ±1.02%. The evaluation of system suitability, precision, robustness and ruggedness parameters were also found to produce satisfactory results. Conclusions: The developed method is very simple and rapid with excellent specificity, accuracy and precision which can be useful for the routine analysis and quantitative estimation of puerarin in plant extracts and formulations. PMID:23781483

  2. Comparative analysis of lycorine in wild plant and callus culture samples of Hymenocallis littoralis by HPLC-UV method.

    PubMed

    Subramaniam, Sreeramanan; Sundarasekar, Jeevandran; Sahgal, Geethaa; Murugaiyah, Vikneswaran

    2014-01-01

    The Hymenocallis littoralis, an ornamental and medicinal plant, had been traditionally used for wound healing. In the present study, an analytical method using HPLC with ultraviolet detection was developed for the quantification of lycorine in the extracts of different parts of wild plant and tissue culture samples of H. littoralis. The separation was achieved using a reversed-phase column. The method was found to be accurate, repeatable, and sensitive for the quantification of minute amount of lycorine present in the samples. The highest lycorine content was found in the bulb extract (2.54 ± 0.02 ?g/mg) whereas the least was in the root extract (0.71 ± 0.02 ?g/mg) of the wild plants. Few callus culture samples had high content of lycorine, comparable to that of wild plants. The results showed that plant growth regulators, 2,4-dichlorophenoxyacetic acid (2,4-D) alone at 4.5 ?M (2.58 ± 0.38 ?g/mg) or a combination of 2,4-D at 9.00 ?M with 4.5 ?M of 6-benzylaminopurine (BAP), were the optimum concentrations for the production of high lycorine (2.45 ± 0.15 ?g/mg) content in callus culture. The present analytical method could be of value for routine quantification of lycorine in the tissue culture production and standardization of the raw material or extracts of H. littoralis. PMID:24895650

  3. Development and validation of an HPLC/UV/MS method for simultaneous determination of 18 preservatives in grapefruit seed extract.

    PubMed

    Ganzera, Markus; Aberham, Anita; Stuppner, Hermann

    2006-05-31

    Grapefruit seed extracts are used in cosmetics, food supplements, and pesticides because of their antimicrobial properties, but suspicions about the true nature of the active compounds arose when synthetic disinfectants such as benzethonium or benzalkonium chloride were found in commercial products. The HPLC method presented herein allows the quality assessment (qualitative and quantitative) of these products for the first time. On the basis of a standard mixture of 18 preservatives most relevant for food and grapefruit products, a method was developed allowing the baseline separation of all compounds within 40 min. Optimum results were obtained with a C-8 stationary phase and a solvent system comprising aqueous trifluoroacetic acid, acetonitrile, and 2-propanol. The assay was fully validated and shown to be sensitive (LOD < or= 12.1 ng on-column), accurate (recovery rates > or = 96.1%), repeatable (sigma(rel) < or = 3.5%), precise (intra-day variation < or = 4.5%, interday variation < or = 4.1%), and rugged. Without any modifications the method could be adopted for LC-MS experiments, where the compounds of interest were directly assignable in positive ESI mode. The quantitative results of several products for ecofarming confirmed previous studies, as seven out of nine specimens were adulterated with preservatives in varying composition. The samples either contained benzethonium chloride (2.5-176.9 mg/mL) or benzalkonium chloride (138.2-236.3 mg/mL), together with smaller amounts of 4-hydroxybenzoic acid esters, benzoic acid, and salicylic acid. PMID:16719494

  4. Successive spectrophotometric resolution as a novel technique for the analysis of ternary mixtures of pharmaceuticals.

    PubMed

    Lotfy, Hayam M; Tawakkol, Shereen M; Fahmy, Nesma M; Shehata, Mostafa A

    2014-01-01

    A novel spectrophotometric technique was developed for the simultaneous determination of ternary mixtures, without prior separation steps. This technique was called successive spectrophotometric resolution technique. The technique was based on either the successive ratio subtraction or successive derivative subtraction. The mathematical explanation of the procedure was illustrated. In order to evaluate the applicability of the methods a model data as well as an experimental data were tested. The results from experimental data related to the simultaneous spectrophotometric determination of lidocaine hydrochloride (LH), calcium dobesilate (CD) and dexamethasone acetate (DA); in the presence of hydroquinone (HQ), the degradation product of calcium dobesilate were discussed. The proposed drugs were determined at their maxima 202 nm, 305 nm, 239 nm and 225 nm for LH, CD, DA and HQ respectively; by successive ratio subtraction coupled with constant multiplication method to obtain the zero order absorption spectra, while by applying successive derivative subtraction they were determined at their first derivative spectra at 210 nm for LH, 320 nm or P(292-320) for CD, 256 nm or P(225-252) for DA and P(220-233) for HQ respectively. The calibration curves were linear over the concentration range of 2-20 ?g/mL for both LH and DA, 6-50 ?g/mL for CD, and 3-40 ?g/mL for HQ. The proposed methods were checked using laboratory-prepared mixtures and were successfully applied for the analysis of pharmaceutical formulation containing the cited drugs with no interference from other dosage form additives. The proposed methods were validated according to the ICH guidelines. The obtained results were statistically compared with those of the official BP methods for LH, DA, and CD, and with the official USP method for HQ; using student t-test, F-test, and one way ANOVA, showing no significant difference with respect to accuracy and precision. PMID:24263128

  5. Estimation of Amlodipine Besylate, Valsartan and Hydrochlorothiazide in Bulk Mixture and Tablet by UV Spectrophotometry

    PubMed Central

    Galande, Varsha R.; Baheti, K. G.; Indraksha, S.; Dehghan, M. H.

    2012-01-01

    A simple, precise, accurate and economic simultaneous UV spectrophotometric method has been developed for the estimation of amlodipine besylate, valsartan and hydrochlorothiazide in combination in bulk mixture and tablet. The estimation was based upon measurement of absorbance at absorbance maxima of 359 nm, 317 nm and 250 nm for amlodipine besylate, hydrochlorothiazide and valsartan in methanol, respectively in bulk mixture and tablet. The Beer Lambert's law obeyed in the concentration range 5-25 ?g/ml, 10-50 ?g/ml and 5-25 ?g/ml for amlodipine besylate, hydrochlorothiazide and valsartan, respectively. The estimation of bulk mixture and tablet was carried out by simultaneous equation, Q-analysis and area under curve method for estimation of amlodipine besylate and hydrochlorothiazide and standard curve method for estimation of valsartan. The results were found to be in the range of 99.6±1.52% to 102±0.51%. Method was validated with respect to specificity, linearity, range, accuracy, precision, LOD, LOQ, robustness, ruggedness and can be applied for routine analysis of tablet dosage forms. PMID:23204617

  6. The Spectrophotometric Analysis and Modeling of Sunscreens

    NASA Astrophysics Data System (ADS)

    Walters, Christina; Keeney, Allen; Wigal, Carl T.; Johnston, Cynthia R.; Cornelius, Richard D.

    1997-01-01

    Sunscreens and their SPF (Sun Protection Factor) values are the focus of this experiment that includes spectrophotometric measurements and molecular modeling. Students suspend weighed amounts of sunscreen lotions graded SPF 4, 6, 8, 15, 30, and 45 in water and dissolve aliquots of the aqueous suspensions in propanol. The expected relationship of absorbance proportional to log10(SPF) applies at 312 nm where a maximum in absorbance occurs for the sunscreen solutions. Results at 330 nm give similar results and are more accessible using spectrometers routinely available in the introductory laboratory. Sunscreens constitute a suitable class of compounds to use for modeling electronic spectra, and using the computer for the active ingredients ethylhexyl para-methoxycinnamate, oxybenzone, 2-ethylhexyl salicylate, and octocrylene found in commercially available formulations typically predicts the absorption maxima within 10 nm. This experiment lets students explore which compounds have the potential to function as sunscreen agents and thereby see the importance of a knowledge of chemistry to the formulation of household items.

  7. Spectrophotometric Time Series of ? Carinae's Great Eruption

    NASA Astrophysics Data System (ADS)

    Rest, Armin; Bianco, Federica; Chornock, Ryan; Clocchiatti, Alejandro; James, David; Margheim, Steve; Matheson, Thomas; Prieto, Jose Luis; Smith, Chris; Smith, Nathan; Walborn, Nolan; Welch, Doug; Zenteno, Alfredo

    2014-08-01

    ? Car serves as our most important template for understanding non-SN transients from massive stars in external galaxies. However, until recently, no spectra were available because its historic ``Great Eruption'' (GE) occurred from 1838-1858, before the invention of the astronomical spectrograph, and only visual estimates of its brightness were recorded teSF11. Now we can also obtain a spectral sequence of the eruption through its light echoes we discovered, which will be of great value since spectra are our most important tool for inferring physical properties of extragalactic transients. Subsequent spectroscopic follow-up revealed that its outburst was most similar to those of G-type supergiants, rather than reported LBV outburst spectral types of F-type (or earlier) teRest12_eta. These differences between the GE and the extragalactic transients presumed to be its analogues raise questions about traditional scenarios for the outburst. We propose to obtain a spectrophotometric time series of the GE from different directions, allowing the original eruption of ? Car to be studied as a function of time as well as latitude, something only possible with light echoes. This unique detailed spectroscopic study of the light echoes of ? Car will help us understand (episodic) mass- loss in the most massive evolved stars and their connection to the most energetic core-collapse SNe.

  8. Epidermal UV-screening in vascular plants from Svalbard

    Microsoft Academic Search

    Line Nybakken; Wolfgang Bilger; Ulf Johanson; Lars Olof Bjorn; Mathias Zielke; Bjørn Solheim; Norwegian Arctic

    Stratospheric ozone depletion is most pro- nounced at high latitudes, and the concurring increased UV-B radiation might adversely affect plants from polar areas. However, vascular plants may protect themselves against UV-B radiation by UV-absorbing compounds located in the epidermis. In this 3-year study, epidermal UV-B (kmax 314 nm) and UV-A (kmax 366 nm) screening was assessed using a fluorescence method

  9. Rapid, on-site identification of explosives in nanoliter droplets using a UV reflected fiber optic sensor.

    PubMed

    Li, Xin; Li, Qiang; Zhou, Hong; Hao, Hongxia; Wang, Tongzhou; Zhao, Songmin; Lu, Ying; Huang, Guoliang

    2012-11-01

    A portable UV (190-400 nm) spectrophotometric based reflected fiber optic sensor system is presented for the on-site detection and identification of explosives. A reflected fiber optic sensor for explosives analysis was developed, with low sample consumption (20-100 nL) and a wide concentration quantification range (1.1-250 mg L(-1)). Seven common explosives [pentaerythritol tetranitrate (PETN), trinitrophenylmethylnitramine (CE), trinitrotoluene (TNT), dinitrotoluene (DNT), picric acid (PA), cyclotetramethylenetetranitramine (HMX), cyclotrimethylenetrinitramine (RDX)] and a PETN-RDX mixture (to simulate the Semtex used in many terrorist bombings) were quantitatively analyzed and identified by the proposed system in less than 3s per test, with limits of detection (LOD) of 0.3 mg L(-1). Due to chemical interference problems in the UV wavelengths range, a novel feature matching algorithm (FMA) was proposed for explosive identification, which was proved to have higher specificity and better anti-interference ability. Real post-blast debris samples were analyzed by the proposed method, and the results were validated against an LC/MS/MS method. The rapid, cost-effective detection with low sample consumption and wide applicability achieved by this system is highly suitable for homeland security on-site applications, such as rapid sample screening in post-blast debris. PMID:23084059

  10. Spectrophotometric readout for an alanine dosimeter for food irradiation applications

    NASA Astrophysics Data System (ADS)

    Ebraheem, S.; Beshir, W. B.; Eid, S.; Sobhy, R.; Kovács, A.

    2003-06-01

    The alanine-electron spin resonance (EPR) readout system is well known as a reference and transfer dosimetry system for the evaluation of high doses in radiation processing. The high cost of an EPR/alanine dosimetry system is a serious handicap for large-scale routine application in irradiation facilities. In this study, the use of a complex produced by dissolving irradiated L-alanine in 1,4-phenyl diammonium dichloride solution was investigated for dosimetry purposes. This complex—having a purple colour—has an increasing absorbance with increasing dose in the range of 1-20 kGy. The applicability of spectrophotometric evaluation was studied by measuring the absorbance intensity of this complex at 360 and 505 nm, respectively. Fluorimetric evaluation was also investigated by measuring the emission of the complex at 435 nm as a function of dose. The present method is easy for routine application. The effect of the dye concentration as well as the suitable amount of irradiated alanine has been studied. With respect to routine application, the stability of the product complex after its formation was also investigated.

  11. The research of UV curing injection molding

    NASA Astrophysics Data System (ADS)

    Xie, Pengcheng; Chang, Le; Song, Le; Cai, Tianze; Ding, Yumei; Yang, Weimin

    2015-05-01

    The micro-injection molding technology and the UV (ultraviolet) curing technique are combined to bring about a new plastic forming method, UV curing injection molding. The mean weight of micro-product is an important process characteristic for UV curing injection molding as well as the surface quality of micro-features is another important process characteristic for this new plastic forming method. This research investigates three effects of processing factors on the mass-change rate of micro-product and the surface quality of micro-features. In every particular, the following two factors are considered: UV material system temperature and the packing pressure. The study revealed that as usual, the micro-products gain weight with the imported increasing UV material system temperature and the improved packing pressure. Meanwhile, the increasing packing pressure also improves the surface quality, yet, warming the UV system temperature up has no effect on the quality of the product.

  12. Development of HPLC method by UV-VIS detection for the quantification of phenolic acids in different Ocimum sanctum Linn. extracts.

    PubMed

    Shafqatullah; Khan, Rasool; Hassan, Waseem; Hussain, Arshad; Asadullah; Rehman, Khaliqur; Ali, Javid

    2014-09-01

    A simple and rapid chromatographic method has been developed for the simultaneous determination of five phenolic acids including Gallic acid, Chloroganic acid, Syringic acid, Benzoic acid and Vanillic acid by HPLC with UV-VIS detector. These Phenolic acids were separated by analytical column Intersil ODS-3 C18, a gradient elution system of ACN and acidified water solution with 1ml/min flow rate and quantified in a total run of 30 minutes at 210nm wavelength. In the quantitative analysis of these compounds showed good regression (0.995-0.999). The limit of detection [LOD] and limit of quantification [LOQ] of these compounds were in the range of 0.15-0.46 and 0.42-2.47 ?g/mL. The average recoveries were between 95.8-103.1% and their RSD values were less than 3.34%. By the proposed method Gallic acid, Chloroganic acid and Syringic acid were found and quantified in Methanolic, Ethanolic and Acetonic extract of Ocimum sanctum Linn. leaves. While the two other phenolic acids benzoic acid and vanillic acid was not found in the extracts of Ocimum sanctum Linn. leaves. PMID:25176382

  13. Analysis of ACE inhibitors in pharmaceutical dosage forms by derivative UV spectroscopy and liquid chromatography (HPLC)

    Microsoft Academic Search

    D Bonazzi; R Gotti; V Andrisano; V Cavrini

    1997-01-01

    Derivative UV spectroscopy and high performance liquid chromatography (HPLC) were applied to the determination of angiotensin-converting enzyme (ACE) inhibitors in their pharmaceutical dosage forms. For spectrophotometric determinations, the more appropriate derivative order was selected for each drug: ramipril (third-order), benazepril (second-order), enalapril maleate (second-order), lisinopril (first- and second-order) and quinapril (first-order). Reverse phase HPLC procedures (ODS column) were developed able

  14. Spectrophotometric determination of benzydamine HCl, levamisole HCl and mebeverine HCl through ion-pair complex formation with methyl orange

    Microsoft Academic Search

    Akram M. El-Didamony

    2008-01-01

    A simple, rapid and sensitive spectrophotometric method has been proposed for the assay of benzydamine HCl (BENZ), levamisole HCl (LEV) and mebeverine HCl (MBV) in bulk and pharmaceutical formulations. The method based on the reaction of the selected drugs with methyl orange (MO) in buffered aqueous solution at pH 3.6. The formed yellow ion-pair complexes were extracted with dichloromethane and

  15. Spectrophotometric determination of isoxsuprine hydrochloride using 3-methyl-2-benzothiazolinone hydrazone hydrochloride in spiked human urine and pharmaceuticals

    Microsoft Academic Search

    Kalsang Tharpa; Kanakapura Basavaiah; Hosakere Doddarevanna Revanasiddappa; Kanakapura Basavaiah Vinay

    2010-01-01

    Two selective and sensitive spectrophotometric methods are proposed for the determination of isoxsuprine hydrochloride (ISX) in spiked human urine and in pharmaceuticals. The methods are based on the oxidative-coupling reaction between 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) and ISX in the presence of Ce(SO4)2. The novelty of the proposed reaction is the formation of two different colored chromogens at two different pHs.

  16. Development of an HPLC-UV Method for the Analysis of Drugs Used for Combined Hypertension Therapy in Pharmaceutical Preparations and Human Plasma

    PubMed Central

    2013-01-01

    A simple, rapid, and selective HPLC-UV method was developed for the determination of antihypertensive drug substances: amlodipine besilat (AML), olmesartan medoxomil (OLM), valsartan (VAL), and hydrochlorothiazide (HCT) in pharmaceuticals and plasma. These substances are mostly used as combinations. The combinations are found in various forms, especially in current pharmaceuticals as threesome components: OLM, AML, and HCT (combination I) and AML, VAL, and HCT (combination II). The separation was achieved by using an RP-CN column, and acetonitrile-methanol-10?mmol orthophosphoric acid pH 2.5 (7?:?13?:?80, v/v/v) was used as a mobile phase; the detector wavelength was set at 235?nm. The linear ranges were found as 0.1–18.5??g/mL, 0.4–25.6??g/mL, 0.3–15.5??g/mL, and 0.3–22??g/mL for AML, OLM, VAL, and HCT, respectively. In order to check the selectivity of the method for pharmaceutical preparations, forced degradation studies were carried out. According to the validation studies, the developed method was found to be reproducible and accurate as shown by RSD ?6.1%, 5.7%, 6.9%, and 4.6% and relative mean error (RME) ?10.6%, 5.8%, 6.5%, and 6.8% for AML, OLM, VAL, and HCT, respectively. Consequently, the method was applied to the analysis of tablets and plasma of the patients using drugs including those substances. PMID:23634320

  17. Improvement of UV Protection Properties of the Textile from Natural Fibres by the Sol-gel Method

    NASA Astrophysics Data System (ADS)

    Vihodceva, S.; Kukle, S.

    2013-12-01

    In this research pure cotton textile was successfully modified by zinc oxide nanosol prepared by the sol-gel method. The cotton fabric was dipped in the nanosol solution for 10 minutes, dried at 90 °C for 10 minutes with further thermal post-treatment at 120 °C, 140 °C or 160 °C for 2 minutes. Comparison of coating of samples prepared using different thermal post-treatments was made. Before and after laundering tests ultraviolet protective properties of the textile samples were determined according to the standards, results show that textiles after treatment with nanosol have excellent ultraviolet protection properties, as well treated samples after laundering tests (50 washing-drying cycles) still provide excellent ultraviolet protection. Analyses based on the scanning electron microscopy and spectrophotometer measurements show that obtained textile coatings are distributed evenly, not only on the surface of yarns but in the depth of textile material as well, and are resistant to exploitation process that indicates about very good adhesion between the coating and the fabric surface.

  18. Optimization and Validation of RP-HPLC-UV/Vis Method for Determination Phenolic Compounds in Several Personal Care Products

    PubMed Central

    Akkbik, Mohammed; Assim, Zaini Bin; Ahmad, Fasihuddin Badruddin

    2011-01-01

    An HPLC method with ultraviolet-visible spectrophotometry detection has been optimized and validated for the simultaneous determination of phenolic compounds, such as butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) as antioxidants, and octyl methyl cinnamate (OMC) as UVB-filter in several personal care products. The dynamic range was between 1 to 250?mg/L with relative standard deviation less than 0.25% (n = 4). Limits of detection for BHA, BHT, and OMC were 0.196, 0.170, and 0.478?mg/L, respectively. While limits of quantification for BHA, BHT, and OMC were 0.593, 0.515, and 1.448?mg/L, respectively. The recovery for BHA, BHT, and OMC was ranged from 92.1–105.9%, 83.2–108.9%, and 87.3–103.7%, respectively. The concentration ranges of BHA, BHT, and OMC in 12 commercial personal care samples were 0.13–4.85, 0.16–2.30, and 0.12–65.5?mg/g, respectively. The concentrations of phenolic compounds in these personal care samples were below than maximum allowable concentration in personal care formulation, that is, 0.0004–10?mg/g, 0.002–5?mg/g, and up to 100?mg/g for BHA, BHT, and OMC, respectively. PMID:21760792

  19. UV water disinfector

    DOEpatents

    Gadgil, A.; Garud, V.

    1998-07-14

    A UV disinfector with a gravity driven feed water delivery system and an air-suspended bare UV lamp are disclosed. The disinfector is hydrodynamically optimized with a laminerizing, perforated baffle wall, beveled treatment chamber, and outlet weir. 7 figs.

  20. UV water disinfector

    DOEpatents

    Gadgil, Ashok (El Cerrito, CA); Garud, Vikas (Bombay, IN)

    1998-07-14

    A UV disinfector with a gravity driven feed water delivery system, and an air-suspended bare UV lamp. The disinfector is hydrodynamically optimized with a laminerizing, perforated baffle wall, beveled treatment chamber, and outlet weir.

  1. Oxygen radical production in bluegill sunfish liver microsomes exposed to anthracene and UV radiation

    SciTech Connect

    Choi, J.; Oris, J. [Miami Univ., Oxford, OH (United States). Dept. of Zoology

    1995-12-31

    Many polycyclic aromatic hydrocarbons (PAHs) are acutely toxic to fish in the presence of ultraviolet radiation. Oxygen radicals are very reactive and are responsible for many cellular injuries including membrane peroxidation and DNA fragmentation. In this research increased oxygen radical production was hypothesized for the mechanism of UV-PAH acute toxicity. In order to test this hypothesis Bluegill sunfish (Lepomis machrochirus) liver microsomes were exposed to anthracene and UV radiation in four different combinations: (No UV + No Ant), (No UV + Ant), (UV + No Ant), (UV + Ant). The production of superoxide anion was quantified by measuring the spectrophotometric absorbance of acetylated cytochrome c, which is reduced by superoxide anion. 1 ml of reaction solution contained 1 mg of microsomes and, for Ant treatments, 7.7 {micro}g of anthracene. After 3 hours preincubation, acetylated cytochrome c solution was added. The UV treatment groups were exposed to UV-A for 20 minutes at 37 C. The highest mean concentration of reduced acetylated cytochrome c was found in the UV + Ant treatment group and it was significantly different from all other treatment groups. No significant differences were observed among the other three treatment groups. This result coincides with previous studies revealing that anthracene is acutely toxic to fish only under UV radiation, and it implies that the photoinduced toxicity of anthracene, as well as other PAHs, is manifested by the action of oxygen radicals.

  2. UV-Visible Spectroscopy

    NSDL National Science Digital Library

    Clark, Jim

    This webpage, part of a larger project "Understanding Chemistry", provides an introduction to UV-visible spectroscopy suitable for use in introductory chemistry and introductory analytical chemistry courses. The pages discuss UV-visible light, absorption, Beer's law, the double-beam spectrometer, and introduce some standard applications of UV-vis spectroscopy.

  3. The use of HPGPC for determination of MWD of asphalt cement - A spectrophotometric vs. gravimetric finish

    SciTech Connect

    Bishara, S.W.; McReynolds, R.L. (Kansas Dept. of Transportation, Topeka (United States))

    1990-07-01

    A comparison between spectrophotometric and gravimetric methods to study MWD of asphalt is presented. Spectrophotometry suffers from not detecting saturated compounds, as well as from variation of molar absorptivity during analysis. To address these shortcoming, the whole asphalt sample is fractionated, and the relative molar absorptivity determined for each fraction. Using another sample weight of the whole asphalt, the saturates are separated, and injected to get their MWD using refractive index detection. This information, when used to mathematically treat the whole asphalt distribution data, can correct the latter to include saturates as well, but can only partially account for continuous variation of the molar absorptivity.

  4. Extractive spectrophotometric determination of trace amounts of sulfur dioxide in air

    SciTech Connect

    Kumar, B.S.M.; Balasubramanian, N. [Indian Institute of Technology, Department of Chemistry, Madras (India)

    1992-11-01

    A sensitive spectrophotometric method was developed for the determination of trace amounts of sulfur dioxide (SO{sub 2}) in air after SO{sub 2} has been fixed in a buffered formaldehyde solution. The reaction of iodate with the fixed SO{sub 2} in the presence of an acid an an excess of chloride leads to the formation of ICI{sub 2} ions. The resulting ICI{sub 2} species forms an ion-pair with pararosaniline cation; the product is extracted into isopentyl alcohol and measured spectrophotometrically at 560 nm. The color system obeys Beer`s law over the range 0-40 {mu}g SO{sub 2}. The color is stable for 72 h from the time of extraction. The molar absorption coefficient of the color system is 4.5 {times} 10{sup 3}Lmol{sup {minus}1}cm{sup {minus}1}. The coefficient of variation is 3.6% for 10 determinations at 20 {mu}g SO{sub 2}. The effect of interfering gases on the determination is discussed. The method was applied to the determination of SO{sub 2} at low concentrations, and the results obtained were compared with the widely used West and Gaeke method. The method can be used to determine as low as 2 {mu}g SO{sub 2}. 12 refs., 2 figs., 2 tabs.

  5. Spectrophotometric Mapping of Coprates Quadrangle, Mars

    NASA Astrophysics Data System (ADS)

    Geissler, Paul Eric

    1992-01-01

    This volume describes the application of quantitative image analysis as a means of investigating the geologic history of the Valles Marineris region of Mars. Three approaches are employed for extracting geological information from Viking Orbiter images. First, multispectral composites are studied for color variations among geologic units and to map their spatial distribution in Coprates Quadrangle. Multitemporal images are next examined for variable features of the martian surface and atmosphere. Finally, multiple phase-angle images are analyzed for variations in the photometric phase function of the surface. The results suggest that volcanism, tectonism, magmatic intrusion and eolian redistribution have each played a part in shaping the martian canyons. Several distinct spectrophotometric units are recognized in Coprates Quadrangle on the basis of the imaging data. The dark red Lunae plains are spectrally and photometrically related to the brighter dust-mantled plains, canyon wall rock and interior layered sediments, indicating a physical and not compositional difference between these materials. Spectrally exceptional sedimentary deposits are evidence for compositional diversity among the bright materials and suggest multiple origins for the layered sediments. Exposed competent bedrock surfaces include lowlying Hesperian volcanic plains and a series of cliffs interpreted as a possible sill. Dark gray, friable and incompetent materials include an in-situ Noachian wall rock layer and locally generated dune-forming sands. These materials are found to be markedly forward -scattering, casting doubt on notions that these dune deposits are composed of lithic fragments or dust grain aggregates, two of the proposed sources for the puzzling martian sands. Interpretation of this unit as a voluminous regional malic tuff deposit may have important implications for the style of past volcanism on Mars. Bright gray materials include young, possibly recent volcanics with a derived distribution consistent with the interpretation of extrusion along faults near the margins of the canyon floors. This result supports the hypothesis that the Valles originated through tectonic extension, which along with volcanism, generation of dark sands, and eolian deposition and erosion of bright dust from global storms, are processes which may continue in the Valles Marineris today.

  6. Spectrophotometric determination of niobium(V) as a mixed ligand complex with gallic acid and 1,2-diaminocyclohexanetetraacetic acid

    Microsoft Academic Search

    M. Subbarao; K. Srinivasulu

    1976-01-01

    Niobium(V) was determined as a mixed ligand complex with gallic acid and 1,2-diaminocyclohexanetetraacetic acid in tartrate medium by a spectrophotometric method at 470 nm around pH 2.5, 40 minutes after preparation of the solution and at 25°C. The system conforms to Beer's law for an optimum range of 0.38 to 8.92 ..mu..g\\/ml of niobium with relative standard deviation of 2

  7. A simple LC method with UV detection for the analysis of creatine and creatinine and its application to several creatine formulations.

    PubMed

    Dash, Alekha K; Sawhney, Angeli

    2002-07-31

    The objective of this study was to develop a simple and sensitive LC method for the determination of creatine and creatinine in various creatine supplement formulations. The chromatographic system comprised of a LC-600 pump, SCL-6B system controller, and SPD-6AV detector (Shimadzu, Japan). The mobile phase consisted of 0.045 M ammonium sulfate in water. The chromatographic separation was achieved at ambient temperature on a Betabasic C-18 column (250 x 4.6 mm, Keystone Sci.). The flow rate was maintained at 0.75 ml/min and effluents are monitored at 205 nm. 4-(2-Aminoethyl)benzene sulfonamide was used as an internal standard (IS). This method required less than 7 min of chromatographic time. The standard curves were linear over the concentration range of 1-100 microg/ml for creatine and 2-100 microg/ml for creatinine, respectively. The relative standard deviations (RSD) for the within-day and day-to-day precision for creatine were within 1.0-4.6 and 2.2-4.7%, respectively. The RSD for the accuracy of creatine assay was in the range of 2.4-4.7%. The RSD values for the within-day precision, day-to-day precision and accuracy for creatinine validation were 1.7-4.4, 2.3-5.4 and 2.4-4.8%, respectively. This method was used to determine: (i) the creatine concentration in various marketed products; (ii) saturated solubility of various creatine salts; and (iii) stability of creatine in aqueous solution. In conclusion, a simple and sensitive LC method with UV detection was developed for the simultaneous determination of creatine and creatinine in formulations. Di-creatine citrate salt showed a higher aqueous solubility (at 25 degrees C) as compared to creatine and creatine monohydrate. Some of the over-the-counter (OTC) products tested contained a very low level of creatine in contrast to their label claim. Substantial conversion of creatine into creatinine was noticed in liquid formulation. PMID:12093528

  8. TOMS UV Algorithm: Problems and Enhancements. 2

    NASA Technical Reports Server (NTRS)

    Krotkov, Nickolay; Herman, Jay; Bhartia, P. K.; Seftor, Colin; Arola, Antti; Kaurola, Jussi; Kroskinen, Lasse; Kalliskota, S.; Taalas, Petteri; Geogdzhaev, I.

    2002-01-01

    Satellite instruments provide global maps of surface ultraviolet (UV) irradiance by combining backscattered radiance measurements with radiative transfer models. The models are limited by uncertainties in input parameters of the atmosphere and the surface. We evaluate the effects of possible enhancements of the current Total Ozone Mapping Spectrometer (TOMS) surface UV irradiance algorithm focusing on effects of diurnal variation of cloudiness and improved treatment of snow/ice. The emphasis is on comparison between the results of the current (version 1) TOMS UV algorithm and each of the changes proposed. We evaluate different approaches for improved treatment of pixel average cloud attenuation, with and without snow/ice on the ground. In addition to treating clouds based only on the measurements at the local time of the TOMS observations, the results from other satellites and weather assimilation models can be used to estimate attenuation of the incident UV irradiance throughout the day. A new method is proposed to obtain a more realistic treatment of snow covered terrain. The method is based on a statistical relation between UV reflectivity and snow depth. The new method reduced the bias between the TOMS UV estimations and ground-based UV measurements for snow periods. The improved (version 2) algorithm will be applied to re-process the existing TOMS UV data record (since 1978) and to the future satellite sensors (e.g., Quik/TOMS, GOME, OMI on EOS/Aura and Triana/EPIC).

  9. Simultaneous determination of cefdinir and cefixime in human plasma by RP-HPLC\\/UV detection method: Method development, optimization, validation, and its application to a pharmacokinetic study

    Microsoft Academic Search

    Abbas Khan; Zafar Iqbal; Muhammad Imran Khan; Khalid Javed; Abad Khan; Lateef Ahmad; Yasar Shah; Fazli Nasir

    2011-01-01

    A novel isocratic reversed-phase high performance liquid-chromatography\\/ultraviolet detection method for simultaneous determination of cefdinir and cefixime in human plasma was developed and validated after optimization of various chromatographic conditions and other experimental parameters. Sample preparation based on a simple extraction procedure consisting of deproteination and extraction with 3 parts of 6% trichloroacetic acid aqueous solution followed by volume make up

  10. Evaluation of two mouth rinses in reduction of oral malodor using a spectrophotometric technique

    PubMed Central

    Malhotra, Sumit; Yeltiwar, R. K.

    2011-01-01

    Background: Various mouth rinses have been used in the treatment of halitosis, but most of the evidence for the efficacy of mouth rinses is anecdotal. In the present study, 0.2% chlorhexidine rinse and an essential oil mouth rinse are compared for their efficacy in reducing the breath mercaptan levels. Materials and Methods: Fifteen patients with the chief complaint of oral malodor were randomly divided into 3 groups and were provided with the respective mouth rinses. Pre rinsing measurements were performed on the Day 1 and no other periodontal treatment was instituted. Post rinsing estimation of mercaptan levels was performed after 7 days. Results: When comparing chlorhexidine with the essential oil mouth rinse, the reduction in VSCs was highly significant in the chlorhexidine group (P<0.01). However, the reduction in the organoleptic scores was not significant among the two groups. Organoleptic scores showed very highly significant correlations with the VSC concentrations measured by the spectrophotometric method. Conclusion: The spectrophotometric technique employed in this study appears to be a promising new method for evaluation of oral malodor. Chlorhexidine still appears to be the agent of choice as a short term regimen in cases of oral malodor. PMID:22028512

  11. A spectrophotometric survey of stars along the Milky Way. IV

    Microsoft Academic Search

    B. A. Rydstrom

    1978-01-01

    In the present paper a catalogue of spectrophotometric quantities, spectral types, monochromatic magnitudes and colour equivalents is given for all stars brighter than the magnitude m4400 = 10.5 in a region of the Milky Way in Perseus. No absorption is found for stars closer than about r = 100 pc. The absorbing clouds are situated at distances closer than 1

  12. Spectrophotometric Titration of a Mixture of Calcium and Magnesium.

    ERIC Educational Resources Information Center

    Fulton, Robert; And Others

    1986-01-01

    Describes a spectrophotometric titration experiment which uses a manual titration spectrophotometer and manually operated buret, rather than special instrumentation. Identifies the equipment, materials, and procedures needed for the completion of the experiment. Recommends the use of this experiment in introductory quantitative analysis…

  13. Preparation and Spectrophotometric Analysis of Hexaamminenickel(II) Chloride.

    ERIC Educational Resources Information Center

    Wieder, Grace M.

    1986-01-01

    Describes an experiment developed at Brooklyn College (New York) in which the preparation and ammonia analysis of an amminenickel(II) chloride is extended to include a spectrophotometric analysis for nickel. Discusses the materials needed and the procedure for the experiment which takes nine hours of laboratory work. (TW)

  14. Determination of human skin optical properties from spectrophotometric measurements based

    E-print Network

    Aguilar, Guillermo

    Abstract. We present an initial study on applying genetic algorithms (GA) to retrieve human skin optical-Optical Instru- mentation Engineers. [DOI: 10.1117/1.1891147] Keywords: genetic algorithms; skin opticalDetermination of human skin optical properties from spectrophotometric measurements based

  15. Spectrophotometric phytochrome measurements in light-grown Avena sativa L

    Microsoft Academic Search

    Merten Jabben I; Gerald F. Deitzer

    1978-01-01

    Phytochrome was studied spectrophotometrically in Avena sativa L. seedlings that had been grown for 6 d in continous white fluorescent light from lamps. Greening was prevented through the use of the herbicide San 9789. When placed in the light, phytochrome (Ptot) decreased with first order kinetics (t1\\/2 ˜ 2 h) but reached a stable low level (˜2.5% of the dark

  16. Simultaneous determination of cefdinir and cefixime in human plasma by RP-HPLC/UV detection method: Method development, optimization, validation, and its application to a pharmacokinetic study.

    PubMed

    Khan, Abbas; Iqbal, Zafar; Khan, Muhammad Imran; Javed, Khalid; Khan, Abad; Ahmad, Lateef; Shah, Yasar; Nasir, Fazli

    2011-08-15

    A novel isocratic reversed-phase high performance liquid-chromatography/ultraviolet detection method for simultaneous determination of cefdinir and cefixime in human plasma was developed and validated after optimization of various chromatographic conditions and other experimental parameters. Sample preparation based on a simple extraction procedure consisting of deproteination and extraction with 3 parts of 6% trichloroacetic acid aqueous solution followed by volume make up with the aqueous component of the mobile phase obtained best recoveries of the two analytes. Samples were separated on a Supelco Discovery HS C(18) (150 mm × 4.6 mm, 5 ?m) analytical column protected by a Perkin Elmer C(18) (30 mm × 4.6 mm, 10 ?m) guard cartridge. The mobile phase, methanol/acetonitrile (50/50, v/v):0.05% trifluoroacetic acid (19:81, v/v), operated at 50°C column oven temperature was pumped at a flow rate of 2.0 mL min(-1) and the column eluents were monitored at a wavelength of 285 nm. When Sample was injected into the Perkin Elmer high performance liquid-chromatography system through Rheodyne manual (or auto-sampler) injector equipped with 20 ?L loop, separation was achieved within 4 min. The present method demonstrated acceptable values for selectivity, linearity within the expected concentration range (0.004-5.0 ?g mL(-1); r(2)>0.999 for both analytes), recovery (>95% for cefdinir and >96% for cefixime), precision (%RSD<2.0 for cefdinir and <2.2 for cefixime), sensitivity (limit of detection: 1 ng mL(-1) and lower limit of quantification: 4 ng mL(-1) for both analytes), stability of solutions, and robustness. The method was efficiently applied to a pharmacokinetic study in healthy volunteers. PMID:21782531

  17. Solar UV variability

    NASA Technical Reports Server (NTRS)

    Donnelly, Richard F.

    1989-01-01

    Measurements from the Solar Backscatter Ultraviolet (SBUV) provide solar UV flux in the 160 to 400 nm wavelength range, backed up by independent measurement in the 115 to 305 nm range from the Solar Mesosphere Explorer (SME). The full disc UV flux from spatially resolved measurements of solar activity was modeled, which provides a better understanding of why the UV variations have their observed temporal and wavelength dependencies. Long term, intermediate term, and short term variations are briefly examined.

  18. Supernova Ia Spectra and Spectrophotometric Time Series: Recognizing Twins and the Consequences for Cosmological Distance Measurements

    NASA Astrophysics Data System (ADS)

    Fakhouri, Hannah Kathleen

    In Part I we introduce the method and results of the Twin Supernova analysis. This novel approach to Type Ia supernova standardization is currently only possible with spectrophotometric timeseries observations from the Nearby Supernova Factory. As Chapters 1 through 4 will explore, we select an ideal subset of supernovae, find pairs whose features match well in flux at all wavelengths and times, and test their dispersion in brightness. The analysis is completed in a blinded fashion, ensuring that we are not tuning our results. What we find is that twin supernovae do indeed have a small brightness dispersion. Part II shows two additional analyses related to the standardization of Type Ia supernovae. In Chapter 5 we present a check on the results of Bailey et al. [2009]. Literature supernovae with spectra near maximum light were tested to see how well their magnitudes could be standardized using the flux ratio method of Bailey et al [2009]. Chapter 6 shows a study with data from the Nearby Supernova Factory. Using only the spectrophotometric observations near maximum light, we calculate monochromatic Hubble Diagram residuals for each supernova. Those residuals are then corrected using a flux ratio, similar to Bailey et al. [2009] to test the standardization possibilities using only near-maximum observations.

  19. Estimation of global solar UV index from UV-B irradiance measured with a narrow-band UV-B radiometer

    NASA Astrophysics Data System (ADS)

    Takeshita, Shu; Sasaki, Masako

    2005-08-01

    The global solar UV index is an indicator for notifying the level of harmful solar ultraviolet radiation reaching the surface of the earth and the general public. It was proposed by the WHO/WMO/UNEP/ICNIRP and was standardized by the CIE in 2003. This index is derived from the product of the spectral solar UV irradiance from 250 to 400 nm and the CIE standard of reference erythema spectrum. For calculation of the UV index, the measurement of spectral solar UV irradiance is needed. Spectral radiometry is the best method of measurement of solar UV irradiance, however spectral radiometers are cost prohibitive. On the other hand, a narrow-band solar UV-B radiometer is widely used for measurement of solar UV-B irradiance in the world. The Tokai Solar Radiation Monitoring Network, and the UV Monitoring Network-Japan performed by the National Institute for Environmental Studies are two examples of monitoring networks using narrow-band solar UV-B radiometer in Japan. In this paper an estimation method of the UV index from the measured UV-B irradiance with the narrow-band UV-B radiometer.

  20. Kinetic-spectrophotometric determination of ascorbic acid by inhibition of the hydrochloric acid-bromate reaction

    NASA Astrophysics Data System (ADS)

    Ensafi, Ali A.; Rezaei, B.; Movahedinia, H.

    2002-10-01

    A new analytical method was developed for the determination of ascorbic acid in fruit juice and pharmaceuticals. The method is based on its inhibition effect on the reaction between hydrochloric acid and bromate. The decolourisation of Methyl Orange by the reaction products was used to monitor the reaction spectrophotometrically at 510 nm. The linearity range of the calibration graph depends on bromate concentration. The variable affecting the rate of the reaction was investigated. The method is simple, rapid, relatively sensitive and precise. The limit of detection is 7.6×10 -6 M and calibration rang is 8×10 -6-1.2×10 -3 M ascorbic acid. The relative standard deviation of seven replication determinations of 8×10 -6 and 2×10 -5 M ascorbic acid was 2.8 and 1.7%, respectively. The influence of potential interfering substance was studied. The method was successfully applied for the determination of ascorbic acid in pharmaceuticals.

  1. Comparison of the removal efficiency for organic contaminants on silicon wafers stored in plastic boxes between UV\\/O 3 and ECR oxygen plasma cleaning methods

    Microsoft Academic Search

    Kyunsuk Choi; Tae-Jong Eom; Chongmu Lee

    2003-01-01

    When wafers are stored in a plastic storage box to protect them from airborne contaminants, volatile organics from the polymeric construction material adsorb onto the wafer surface. Both UV\\/O3 and ECR oxygen plasma techniques have been found to completely remove these organic contaminants adsorbed on the silicon surfaces up to the detection limit. After cleaning, Si wafers were characterized using

  2. Comparative study of UV/TiO2, UV/ZnO and photo-Fenton processes for the organic reactive dye degradation in aqueous solution.

    PubMed

    Peternel, Igor T; Koprivanac, Natalija; Bozi?, Ana M Loncari?; Kusi?, Hrvoje M

    2007-09-01

    In this study advanced oxidation processes (AOPs), UV/TiO(2), UV/ZnO and photo-Fenton, were applied in order to degrade C.I. Reactive Red 45 (RR45) dye in aqueous solution. The effects of key operating parameters, such as initial pH, catalyst and hydrogen peroxide dosage as well as the effect of initial dye concentration on decolorization and mineralization extents were studied. Primary objective was to determine the optimal conditions for each of the processes. The influence of added zeolite on the process efficiency was also studied. UV/vis spectrophotometric and total organic carbon (TOC) measurements were performed for determination of decolorization and mineralization extents. It has been found that photo-Fenton process was the most efficient with 74.2% TOC removal and complete color removal achieved after a 1h treatment. PMID:17400374

  3. UV Spectral Dating of Galaxies

    NASA Astrophysics Data System (ADS)

    Heap, Sara

    1997-07-01

    We are working to calculate a highly accurate library of UV stellar spectra that can be used to estimate the age and metallicity of galaxies of intermediate age {between 1 and 8 Gyrs}. The critical step in this effort is to test the model spectra against high-quality UV spectra of real stars. Only by verifying the models in this way can we have confidence in the synthetic spectra, especially those for the very high metallicity found in the cores of elliptical galaxies. We therefore propose to obtain STIS/E230M spectra of 16 late-A and F-type stars for this purpose. We will then use our library of UV spectra in conjunction with current evolutionary models to explore the effects of age, metallicity, non-solar abundance ratios, and IMF on the rest-frame UV spectrum of a galaxy. Our goal is to break the age-metallicity degeneracy that stymies present methods of dating galaxies.

  4. UV Becomes 3Dimensional

    Microsoft Academic Search

    Manfred Biehler; Erich Beck; Klaus Menzel; Sven Titusson; Andreas Daiss

    The usage of radiation curable coatings is well established in the field of flat substrates. UV coatings show both ecological and economical benefits. Five different industrial coating technologies have been compared regarding the coating of doors by using the Ecoefficency Analysis. The results showed that UV curing is the most ecoefficient alternative 1 . The most frequent applications of the

  5. Detectivity of a UV-B photodiode

    NASA Astrophysics Data System (ADS)

    Larrabee, Joseph C.; Baisley, V. C.; Huffman, Robert E.; Meade, Robert D.; Joannopoulos, John D.

    1994-09-01

    This paper reports on the transmission by a thin silver filter of the UV-B band, and on the suitability of this filter for use in combination with a silicon photodiode to make a simple, versatile detector for the UV-B band. The UV-B band, from 280 to 320 nanometers, is considered the most dangerous region of ultraviolet sunlight which reaches the earth's surface, since it is the most likely UV radiation to cause skin cancer. Skin cancer cases are increasing, and the increase is linked to increased surface UV radiation due to the thinning levels of stratospheric ozone. Thus, there is a need to develop simple methods for monitoring UV-B. The fortuitous transmission of silver films in the UV-B band, known to the authors from a single reference, has apparently been overlooked in recent instrumentation papers. The transmission and detectivity measurements given here indicate that thin silver films may indeed have a use in simple UV-B exposure meters.

  6. SPECTROPHOTOMETRIC INTRACUTANEOUS IMAGING (SIASCOPY): METHOD AND CLINICAL APPLICATIONS

    E-print Network

    Claridge, Ela

    a preferred tool for the diagnosis of pigmented skin lesions and early melanoma detection. Other applications an advanced melanoma and a set of SIAgraphs showing the concentration of dermal and epidermal melanin, blood and interpretation of the maps is given in section 5.1. Figure 1. (a) A colour image of a melanoma together

  7. Application of inorganic oxidants to the spectrophotometric determination of ribavirin in bulk and capsules.

    PubMed

    Darwish, Ibrahim A; Khedr, Alaa S; Askal, Hassan F; Mohamed, Ramadan M

    2006-01-01

    Eight spectrophotometric methods for determination of ribavirin have been developed and validated. These methods were based on the oxidation of the drug by different inorganic oxidants: ceric ammonium sulfate, potassium permanganate, ammonium molybdate, ammonium metavanidate, chromium trioxide, potassium dichromate, potassium iodate, and potassium periodate. The oxidation reactions were performed in perchloric acid medium for ceric ammonium sulfate and in sulfuric acid medium for the other reagents. With ceric ammonium sulfate and potassium permanganate, the concentration of ribavirin in its samples was determined by measuring the decrease in the absorption intensity of the colored reagents at 315 and 525 nm, respectively. With the other reagents, the concentration of ribavirin was determined by measuring the intensity of the developed colored reaction products at the wavelengths of maximum absorbance: 675, 780, 595, 595, 475, and 475 nm for reactions with ammonium molybdate, ammonium metavanidate, chromium trioxide, potassium dichromate, potassium iodate, and potassium periodate, respectively. Different variables affecting the reaction conditions were carefully studied and optimized. Under the optimum conditions, linear relationships with good correlation coefficients (0.9984-0.9998) were found between the absorbance readings and the concentrations of ribavirin in the range of 4-1400 microg/mL. The molar absorptivities were correlated with the oxidation potential of the oxidants used. The precision of the methods were satisfactory; the values of relative standard deviation did not exceed 1.64%. The proposed methods were successfully applied to the analysis of ribavirin in pure drug material and capsules with good accuracy and precision; the recovery values were 99.2-101.2 +/- 0.48-1.30%. The results obtained using the proposed spectrophotometric methods were comparable with those obtained with the official method stated in the United States Pharmacopeia. PMID:16640282

  8. Liquid chromatographic and spectrophotometric determination of diflucortolone valerate and isoconazole nitrate in creams.

    PubMed

    Karacan, Elif; Ca?layan, Mehmet Gokhan; Palabiyik, Ismail Murat; Onur, Feyyaz

    2011-01-01

    A new RP-LC method and two new spectrophotometric methods, principal component regression (PCR) and first derivative spectrophotometry, are proposed for simultaneous determination of diflucortolone valerate (DIF) and isoconazole nitrate (ISO) in cream formulations. An isocratic system consisting of an ACE C18 column and a mobile phase composed of methanol-water (95 + 5, v/v) was used for the optimal chromatographic separation. In PCR, the concentration data matrix was prepared by using synthetic mixtures containing these drugs in methanol-water (3 + 1, v/v). The absorbance data matrix corresponding to the concentration data matrix was obtained by measuring the absorbances at 29 wavelengths in the range of 242-298 nm for DIF and ISO in the zero-order spectra of their combinations. In first derivative spectrophotometry, dA/dlambda values were measured at 247.8 nm for DIF and at 240.2 nm for ISO in first derivative spectra of the solution of DIF and ISO in methanol-water (3 + 1, v/v). The linear ranges were 4.00-48.0 microg/mL for DIF and 50.0-400 microg/mL for ISO in the LC method, and 2.40-40.0 microg/mL for DIF and 60.0-260 microg/mL for ISO in the PCR and first derivative spectrophotometric methods. These methods were validated by analyzing synthetic mixtures. These three methods were successfully applied to two pharmaceutical cream preparations. PMID:21391489

  9. A spectrophotometric study of aqueous Au(III) halide-hydroxide complexes at 25-80 °C

    NASA Astrophysics Data System (ADS)

    Usher, Al; McPhail, D. C.; Brugger, Joël

    2009-06-01

    The mobility and transport of gold in low-temperature waters and brines is affected by the aqueous speciation of gold, which is sensitive in particular to pH, oxidation and halide concentrations. In this study, we use UV-Vis spectrophotometry to identify and measure the thermodynamic properties of Au(III) aqueous complexes with chloride, bromide and hydroxide. Au(III) forms stable square planar complexes with hydroxide and halide ligands. Based on systematic changes in the absorption spectra of solutions in three binary systems NaCl-NaBr, NaCl-NaOH and NaBr-NaOH at 25 °C, we derived log dissociation constants for the following mixed and end-member halide and hydroxide complexes: [AuCl 3Br] -, [AuCl 2Br 2] -, [AuBr 3Cl] - and [AuBr 4] -; [AuCl 3(OH)] -, [AuCl 2(OH) 2] -, [AuCl(OH) 3] - and [Au(OH) 4] -; and [AuBr 3(OH)] -, [AuBr 2(OH) 2] - and [AuBr(OH) 3] -. These are the first reported results for the mixed chloride-bromide complexes. Increasing temperature to 80 °C resulted in an increase in the stability of the mixed chloride-bromide complexes, relative to the end-member chloride and bromide complexes. For the [AuCl (4-n)(OH) n] - series of complexes ( n = 0-4), there is an excellent agreement between our spectrophotometric results and previous electrochemical results of Chateau et al. [Chateau et al. (1966)]. In other experiments, the iodide ion (I -) was found to be unstable in the presence of Au(III), oxidizing rapidly to I 2(g) and causing Au to precipitate. Predicted Au(III) speciation indicates that Au(III) chloride-bromide complexes can be important in transporting gold in brines with high bromide-chloride ratios (e.g., >0.05), under oxidizing (atmospheric), acidic (pH < 5) conditions. Native gold solubility under atmospheric oxygen conditions is predicted to increase with decreasing pH in acidic conditions, increasing pH in alkaline conditions, increasing chloride, especially at acid pH, and increasing bromide for bromide/chloride ratios greater than 0.05. The results of our study increase the understanding of gold aqueous geochemistry, with the potential to lead to new methods for mineral exploration, hydrometallurgy and medicine.

  10. An asymptotic method for estimating the vertical ozone distribution in the Earth's atmosphere from satellite measurements of backscattered solar UV-radiation

    NASA Technical Reports Server (NTRS)

    Ishov, Alexander G.

    1994-01-01

    An asymptotic approach to solution of the inverse problems of remote sensing is presented. It consists in changing integral operators characteristic of outgoing radiation into their asymptotic analogues. Such approach does not add new principal uncertainties into the problem and significantly reduces computation time that allows to develop the real (or about) time algorithms for interpretation of satellite measurements. The asymptotic approach has been realized for estimating vertical ozone distribution from satellite measurements of backscatter solar UV radiation in the Earth's atmosphere.

  11. Structural and Morphology of ZnO Nanorods Synthesized Using ZnO Seeded Growth Hydrothermal Method and Its Properties as UV Sensing

    PubMed Central

    Ridhuan, Nur Syafinaz; Abdul Razak, Khairunisak; Lockman, Zainovia; Abdul Aziz, Azlan

    2012-01-01

    In this study, zinc oxide (ZnO) nanorod arrays were synthesized using a simple hydrothermal reaction on ZnO seeds/n-silicon substrate. Several parameters were studied, including the heat-treatment temperature to produce ZnO seeds, zinc nitrate concentration, pH of hydrothermal reaction solution, and hydrothermal reaction time. The optimum heat-treatment temperature to produce uniform nanosized ZnO seeds was 400°C. The nanorod dimensions depended on the hydrothermal reaction parameters. The optimum hydrothermal reaction parameters to produce blunt tip-like nanorods (770 nm long and 80 nm in top diameter) were 0.1 M zinc nitrate, pH 7, and 4 h of growth duration. Phase analysis studies showed that all ZnO nanorods exhibited a strong (002) peak. Thus, the ZnO nanorods grew in a c-axis preferred orientation. A strong ultraviolet (UV) emission peak was observed for ZnO nanorods grown under optimized parameters with a low, deep-level emission peak, which indicated high optical property and crystallinity of the nanorods. The produced ZnO nanorods were also tested for their UV-sensing properties. All samples responded to UV light but with different sensing characteristics. Such different responses could be attributed to the high surface-to-volume ratio of the nanorods that correlated with the final ZnO nanorods morphology formed at different synthesis parameters. The sample grown using optimum synthesis parameters showed the highest responsivity of 0.024 A/W for UV light at 375 nm under a 3 V bias. PMID:23189199

  12. A Spectrophotometric Study on Uranyl Nitrate Complexation to 150?°C

    Microsoft Academic Search

    O. M. Suleimenov; T. M. Seward; J. K. Hovey

    2007-01-01

    The formation constant of the mononitratouranyl complex was studied spectrophotometrically at temperatures of 25, 40, 55,\\u000a 70, 100 and 150?°C (298, 313, 328, 343, 373 and 423 K). The uranyl ion concentration was fixed at approximately 0.008 mol?kg?1 and the ligand concentration was varied from 0.05 to 3.14 mol?kg?1. The uranyl nitrate complex, UO2NO3+, is weak at 298 K but

  13. Child universes UV regularization?

    E-print Network

    E. I. Guendelman

    2007-03-26

    It is argued that high energy density excitations, responsible for UV divergences in quantum field theories, including quantum gravity, are likely to be the source of child universes which carry them out of the original space time. This decoupling prevents these high UV excitations from having any influence on physical amplitudes. Child universe production could therefore be responsible for UV regularization in quantum field theories which takes into account gravitational effects. Also child universe production in the last stages of black hole evaporation, the prediction of absence of tranplanckian primordial perturbations, connection to the minimum length hypothesis and in particular connection to the maximal curvature hypothesis are discussed.

  14. Effect of UV irradiation on the apoptosis and necrosis of Jurkat cells using UV LEDs

    NASA Astrophysics Data System (ADS)

    Inada, Shunko A.; Amano, Hiroshi; Akasaki, Isamu; Morita, Akimichi; Kobayashi, Keiko

    2009-02-01

    Phototherapy is a very effective method for treating most of the incurable skin diseases. A fluorescent light bulb is used as a conventional UV light source for this type of therapy. However, infrared radiation from the light source sometimes causes serious problems on patient's health. In addition, the normal part of the skin is irradiated when a large fluorescent light bulb is used. Moreover, a conventional UV irradiation system is heavy and has a short lifetime and a high electrical power consumption. Therefore, a new UV light source for solving the problems of phototherapy is required. To realize low-power-consumption, lightweight and long-lifetime systems, group III nitride-based UV-A1 light-emitting diodes (LEDs) were investigated. We examined the UV LED irradiation of Jurkat cell, which is a tumor cell and more sensitive to UV light than a healthy cell. The numbers of apoptotic and necrotic cells were confirmed to be the same using a UV LED and a conventional lamp system. The UV LED showed the possibility of realizing a new UV light source for phototherapy.

  15. Sensitive spectrophotometric determination of vanadium in environmental samples at PPB levels

    SciTech Connect

    Agarwal, C.; Deb, M.K.; Mishra, R.K. (Ravishankar Univ., Raipur (India))

    1990-01-01

    A new, sensitive and selective method for separation, and extraction - spectrophotometric determination of V(V) with pyrogallol Ar(OH){sub 3} and hydroxyamidines (HOA) is described. The molar absorptivities of the colored species with six substituted HOA lie in the range of (0.52 - 1.5) {times} 10{sup 6} L mole {sup {minus}1} cm{sup {minus}1} at {lambda}{sub max} 430-440 nm. Of these, the simplest compound, N-hydroxy-N,N{prime}-diphenylbenzamidine(HDPBA) gives the most sensitive color reaction and hence, it is used for detailed studies. No interference of almost all diverse ions tested is noticed. The method offers the determination of vanadium in different environmental samples.

  16. Spectrophotometric determination of vanadium after extraction as vanadium(III) picolinate.

    PubMed

    Yatirajam, V; Arya, S P

    1979-01-01

    Vanadium(V) is conveniently reduced by sodium dithionite to vanadium(III) which is extracted as its picolinate complex into chloroform. Vanadium is determined spectrophotometrically by measuring the absorbance of the complex at 385 nm against a reagent blank, Beer's law being obeyed over the range 1-50 microg/ml. The method is one of the most selective, being free from interference by relatively high concentrations of almost all the important elements, titanium, chromium, manganese, iron, cobalt, nickel, zinc, copper, aluminium, molybdenum, tungsten and uranium, found in industrial alloys. Only bismuth interferes. The method is quite simple and rapid. It has been successfully applied for the analysis of vanadium in a variety of samples. PMID:18962377

  17. Photo-catalyzed degradation of p-nitrophenol employing TiO2 and UV radiations.

    PubMed

    Shintre, Surabhi N; Thakur, Pragati R

    2008-10-01

    Heterogeneous photocatalysis on metal oxide semiconductor particles is an advanced oxidation technology (AOT), which has been effective means of removing organic pollutants from water streams as it utilizes ultraviolet light with semiconductors acting as photocatalyst and leads to complete mineralization of pollutants to environmentally harmless compounds. In the present investigation, the photo-catalyzed degradation studies of p-Nitrophenol (PNP) were carried out in laboratory scale immersion well UV photo-reactor using semiconductor photo-catalyst TiO2 in suspension. For this purpose, low pressure 12 W mercury lamp was used and the effect of (i) time of irradiation, (ii) dose of TiO2, (iii) initial concentration of PNP and (iv) the addition of H2O2 to the system was studied to arrive at optimum process parameters for the complete degradation and decolorization of PNP. Simple UV irradiation could not achieve significant degradation of PNP. But UV+aeration+TiO2+ H2O2 combination achieved almost complete degradation of PNP. The spectrophotometric analysis showed that the rate of degradation of PNP was very fast in initial two hours and the maximum degradation was achieved in 5 hours. The degradation was found to increase in the order UV < UV + aeration < UV + aeration + TiO2 < UV + aeration + TiO2+ H2O2, and the degradation was found to be almost 100% for UV + aeration + TiO2 + H2O2, 91% for UV + aeration + TiO2, 43% for UV + aeration and only 26% for UV irradiation. PMID:19697765

  18. Detecting UV Light

    NSDL National Science Digital Library

    Students learn about ultraviolet light in this Moveable Museum unit, where they detect UV rays and then explore ways to block them. The four-page PDF guide includes suggested general background readings for educators, activity notes, step-by-step directions, and information about where to obtain supplies. Students make a bracelet from beads that respond to UV light by changing color, and test it in different light environments.

  19. Spectrophotometric determination of anthracycline anticancer agents with aluminum(III) and chromazurol S in a nonionic surfactant micellar medium.

    PubMed

    Nakao, Masahiro; Yamazaki, Chikako; Tominaga, Hiroshi; Yamaguchi, Takako; Fujita, Yoshikazu

    2006-02-01

    A simple and highly sensitive spectrophotometric method for the determination of anthracycline anticancer agents, such as Daunorubicin hydrochloride (DAU), was established by using aluminum(III) and Chromazurol S (CAS) in a nonionic surfactant micellar medium. In the case of determination of DAU, the apparent molar absorptivity was 1.3 x 10(5) dm3 mol(-1) cm(-1) at 615 nm. Beer's law was obeyed in the concentration range of 0.028 - 2.82 microg ml(-1) for DAU. Owing to no need for solvent extraction, this method could be applied to assays of DAU and related drugs in pharmaceutical preparations. PMID:16512429

  20. UV signature mutations.

    PubMed

    Brash, Douglas E

    2015-01-01

    Sequencing complete tumor genomes and exomes has sparked the cancer field's interest in mutation signatures for identifying the tumor's carcinogen. This review and meta-analysis discusses signatures and their proper use. We first distinguish between a mutagen's canonical mutations—deviations from a random distribution of base changes to create a pattern typical of that mutagen—and the subset of signature mutations, which are unique to that mutagen and permit inference backward from mutations to mutagen. To verify UV signature mutations, we assembled literature datasets on cells exposed to UVC, UVB, UVA, or solar simulator light (SSL) and tested canonical UV mutation features as criteria for clustering datasets. A confirmed UV signature was: ?60% of mutations are C?T at a dipyrimidine site, with ?5% CC?TT. Other canonical features such as a bias for mutations on the nontranscribed strand or at the 3' pyrimidine had limited application. The most robust classifier combined these features with criteria for the rarity of non-UV canonical mutations. In addition, several signatures proposed for specific UV wavelengths were limited to specific genes or species; UV's nonsignature mutations may cause melanoma BRAF mutations; and the mutagen for sunlight-related skin neoplasms may vary between continents. PMID:25354245

  1. UV disinfection system for cabin air

    NASA Astrophysics Data System (ADS)

    Lim, Soojung; Blatchley, Ernest R.

    2009-10-01

    The air of indoor cabin environments is susceptible to contamination by airborne microbial pathogens. A number of air treatment processes are available for inactivation or removal of airborne pathogens; included among these processes is ultraviolet (UV) irradiation. The effectiveness of UV-based processes is known to be determined by the combined effects of UV dose delivery by the reactor and the UV dose-response behavior of the target microbe(s). To date, most UV system designs for air treatment have been based on empirical approaches, often involving crude representations of dose delivery and dose-response behavior. The objective of this research was to illustrate the development of a UV system for disinfection of cabin air based on well-defined methods of reactor and reaction characterization. UV dose-response behavior of a test microorganism was measured using a laboratory (bench-scale) system. Target microorganisms (bacterial spores) were first applied to membrane filters at sub-monolayer coverage. The filters were then transferred to a humidity chamber at fixed relative humidity (RH) and allowed to equilibrate with their surroundings. Microorganisms were then subjected to UV exposure under a collimated beam. The experiment was repeated at RH values ranging from 20% to 100%. UV dose-response behavior was observed to vary with RH. For example, at 100% RH, a UV dose of 20 mJ/cm 2 accomplished 99.7% (2.5 log10 U) of the Bacillus subtilis spore inactivation, whereas 99.94% (3.2 log10 U) inactivation was accomplished at this same UV dose under 20% RH conditions. To determine reactor behavior, UV dose-response behavior was combined with simulated results of computational fluid dynamics (CFD) and radiation intensity field models. This modeling approach allowed estimating the UV dose distribution delivered by the reactor. The advantage of this approach is that simulation of many reactor configurations can be done in a relatively short period of time. Moreover, by following this approach of "numerical prototyping", it is possible to "build" and analyze several virtual reactors before the construction of a physical prototype. As such, this procedure allows effective development of efficient reactors.

  2. Highly efficient, selective, sensitive and stability indicating RP-HPLC-UV method for the quantitative determination of potential impurities and characterization of four novel impurities in eslicarbazepine acetate active pharmaceutical ingredient by LC/ESI-IT/MS/MS.

    PubMed

    Thomas, Saji; Bharti, Amber; Maddhesia, Pawan Kumar; Shandilya, Sanjeev; Agarwal, Ashutosh; Dharamvir; Biswas, Sujay; Bhansal, Vikas; Gupta, Ashish Kumar; Tewari, Praveen Kumar; Mathela, Chandra S

    2012-03-01

    A novel, sensitive, selective and stability indicating LC-UV method was developed for the determination of potential impurities of eslicarbazepine acetate. High performance liquid chromatographic investigation of eslicarbazepine acetate laboratory sample revealed the presence of several impurities. Three impurities were characterized rapidly and four impurities were found to be unknown. The unknown impurities were identified by liquid chromatography coupled with electrospray ionization, ion trap mass spectrometry (LC/ESI-IT/MS/MS). Structural confirmation of these impurities was unambiguously carried out by synthesis followed by characterization using nuclear magnetic resonance spectroscopy (NMR), infrared spectroscopy (FT-IR) and mass spectrometry (MS). Based on the spectroscopic, spectrometric and elemental analysis data unknown impurities were characterized as 5-acetyl-5,11-dihydro-10H-dibenzo [b,f]azepin-10-one, N-acetyl-5H-dibenzo[b,f]azepine-5-carboxamide, 5-acetyl-10,11-dihydro-5H-dibenzo[b,f]azepin-10-yl acetate and 5-acetyl-5H-dibenzo[b,f]azepin-10-yl acetate. The newly developed LC-UV method was validated according to ICH guidelines considering eleven potential impurities and four new impurities to demonstrate specificity, precision, linearity, accuracy and stability indicating nature of the method. The newly developed method was found to be highly efficient, selective, sensitive and stability indicating. A plausible pathway for the formation of four new impurities is proposed. PMID:22178334

  3. A Sensitive and Simple HPLC-UV Method for Trace Level Quantification of Ethyl p-Toluenesulfonate and Methyl p-Toluenesulfonate, Two Potential Genotoxins in Active Pharmaceutical Ingredients

    PubMed Central

    Nageswari, Amasa; Reddy, Kallam Venkata Siva Rama Krishna; Mukkanti, Khagga

    2011-01-01

    A sensitive and simple HPLC/UV method has been developed and validated for the determination of two potential genotoxic impurities, namely methyl p-toluenesulfonate (MPTS) and ethyl p-toluenesulfonate (EPTS) at trace levels in Pemetrexed sodium API. Applying the concept of threshold of toxicological concern (TTC), a limit of 3 ppm each for both genotoxins was calculated based on the maximum daily dose of API. A reversed phase LC method using UV detection was developed and validated. The method was found to be specific and selective for the application. The limit of detection (LOD) and limit of quantitation (LOQ) for both MPTS and EPTS was found to be 0.15 ppm (0.009 ?g mL?1) and 0.5 ppm (0.03 ?g mL?1), respectively, with respect to sample concentration. The calibration curves of MPTS and EPTS were linear over the concentration range from LOQ to 6 ?g/mL. The method was found to be specific, precise, linear and accurate and has been successfully applied to determine the two genotoxins in commercial batches of the API. PMID:22145110

  4. A Sensitive and Simple HPLC-UV Method for Trace Level Quantification of Ethyl p-Toluenesulfonate and Methyl p-Toluenesulfonate, Two Potential Genotoxins in Active Pharmaceutical Ingredients.

    PubMed

    Nageswari, Amasa; Reddy, Kallam Venkata Siva Rama Krishna; Mukkanti, Khagga

    2011-01-01

    A sensitive and simple HPLC/UV method has been developed and validated for the determination of two potential genotoxic impurities, namely methyl p-toluenesulfonate (MPTS) and ethyl p-toluenesulfonate (EPTS) at trace levels in Pemetrexed sodium API. Applying the concept of threshold of toxicological concern (TTC), a limit of 3 ppm each for both genotoxins was calculated based on the maximum daily dose of API. A reversed phase LC method using UV detection was developed and validated. The method was found to be specific and selective for the application. The limit of detection (LOD) and limit of quantitation (LOQ) for both MPTS and EPTS was found to be 0.15 ppm (0.009 ?g mL(-1)) and 0.5 ppm (0.03 ?g mL(-1)), respectively, with respect to sample concentration. The calibration curves of MPTS and EPTS were linear over the concentration range from LOQ to 6 ?g/mL. The method was found to be specific, precise, linear and accurate and has been successfully applied to determine the two genotoxins in commercial batches of the API. PMID:22145110

  5. Use of zirconium(IV) arsenophosphate columns for cation exchange separation of metal ions interfering in the spectrophotometric determination of uranium with sodium diethyl dithiocarbamate

    SciTech Connect

    Varshney, K.G.; Agrawal, S.; Anwar, S.; Varshney, K.

    1985-01-01

    A simple cation exchange method has been developed for the quantitative separation of uranium from some metal ions which generally interfere in its spectrophotometric determination using sodium diethyl dithiocarbamate as a reagent. The method requires only a single bed operation and enables a satisfactory (Error + or - separation of uranium (UO/sub 2/ (II)) up to 1080 ..mu..g from ten metal ions on a 2 g column of zirconium (IV) arsenophosphate cation exchanger in H(I) form.

  6. Solution-phase synthesis of silver nanodiscs in HPMC-matrix and simulation of UV-vis extinction spectra using DDA based method

    NASA Astrophysics Data System (ADS)

    Sarkar, Priyanka; Pyne, Santanu; Sahoo, Gobinda P.; Bhui, Dipak K.; Bar, Harekrishna; Samanta, Sadhan; Misra, Ajay

    2011-11-01

    Present investigation demonstrates a very simple seed-mediated route, using hydroxypropyl methyl cellulose (HPMC) as stabilizing agent, for the synthesis of silver nanodiscs in aqueous solution. Central to the concept of seed-mediated growth of nanoparticles is that small nanoparticle seeds serve as nucleation centres to grow nanoparticles to a desired size and shape. It is found that the additional citrate ions in the growth solution play the pivotal role in controlling the size of silver nanodiscs. Similar to the polymers in the solution, citrate ions could be likewise dynamically adsorbed on the growing silver nanoparticles and promote the two-dimensional (2D) growth of nanoparticles. Morphological, structural, and spectral changes associated with the seed-mediated growth of the nanoparticles in the presence of HPMC are characterized using UV-vis and TEM spectroscopic studies. Metal nanoparticles have received increasing attention for their peculiar capability to control local surface plasmon resonance (LSPR) when interacting with incident light waves. Extensive simulation study of the UV-vis extinction spectra of our synthesized silver nanodiscs has been carried out using discrete dipole approximation (DDA) methodology.

  7. UV penetration depth in liquid egg white and liquid whole egg

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Knowledge of penetration depth of UV in liquid egg is crucial in designing nonthermal UV pasteurizers. An experimental method was developed to determine penetration depth of 254 nm UV in liquid whole egg (LWE) and liquid egg white (LEW). An apparatus was assembled consisting of a bank of UV bulbs at...

  8. Visible/Near-infrared spectrophotometric blood typing sensor for automated near-patient testing.

    PubMed

    Anthony, Steven; Ramasubramanian, M

    2005-01-01

    Automation in near-patient ABO testing has been prohibitive due to cost. Recently, a spectrophotometric approach to blood typing has been developed by examining the spectral slopes of RBC suspensions in saline, in the presence and absence of various antibodies. In this paper, we present a simplified method and a sensor that can replace the spectral imaging component of the diode-array spectrophotometer with a discrete array of LED/IRED and photodiode pairs within the 660nm-1000nm wavelength range of interest. An experimental sensor has been designed and evaluated for the reproduction of results recorded on an HP8453 diode-array spectrophotometer. The LED and photodiode pairs are found to successfully reproduce the spectroscopic determination of red blood cell agglutination, as supported by Mie scattering theory examined herein. PMID:17282611

  9. Spectrophotometric microdetermination of nefopam, mebevrine and phenylpropanolamine hydrochloride in pharmaceutical formulations using alizarins

    NASA Astrophysics Data System (ADS)

    Shama, S. A.; Amin, A. S.

    2004-07-01

    Simple and rapid spectrophotometric procedures have been established for quantitation of nefopam hydrochloride (NF) mebevrine hydrochloride (MB) and phenylpropanolamine hydrochloride (PP). The procedures are based on the reaction between the examined drugs (NF, MB and PP) and alizarin (I), alizarin red S (II), alizarin yellow G (III) and quinalizarin (IV) producing ion-pair complexes which can be measured at the optimum wavelength. The optimization of the reaction conditions is investigated. Beer's law is obeyed in the concentration ranges 0.5-30.0 ?g ml -1. The molar absorptivity, Sandell sensitivity, detection and quantification limits are also calculated. The correlation coefficient was ?0.9988 ( n=6) with a relative standard deviation (R.S.D.) of ?1.3, for six determinations of 20 ?g ml -1. The methods are successfully applied to the determination of NF, MB and PP in their pharmaceutical formulations.

  10. Spectrophotometric determination of molybdenum by extraction of a green molybdenum(v) species.

    PubMed

    Yatirajam, V; Ram, J

    1973-11-01

    A simple method is described for the rapid spectrophotometric determination of molybdenum in samples containing 1-60% Mo, with satisfactory accuracy. Molybdenum is reduced with excess of hydrazine sulphate in boiling 5.5M hydrochloric acid and extracted with isoamyl acetate from 7M hydrochloric acid. The green colour is measured at 720 nm against a reagent blank. Beer's law is obeyed over the range 0.08-5.4 mg of molybdenum per ml. Interference from iron and copper is removed by adding stannous chloride and thiourea respectively in slight excess. Titanium, vanadium, niobium, chromium, tungsten, nickel, uranium, and antimony do not interfere even in large amounts. Only cobalt interferes seriously. PMID:18961398

  11. UV Disinfection System for Cabin Air

    NASA Astrophysics Data System (ADS)

    Lim, Soojung

    Ultraviolet (UV) radiation is commonly used for disinfection of water. As a result of advancements made in the last 10-15 years, the analysis and design of UV disinfection systems for water is well developed. UV disinfection is also used for disinfection of air; however, despite the fact the UV-air systems have a longer record of application than UV-water systems, the methods used to analyze and design UV-air disinfection systems remain quite empirical. It is well-established that the effectiveness of UV-air systems is strongly affected by the type of microorganisms, the irradiation level/type (lamp power and wavelength), duration of irradiation (exposure time), air movement pattern (mixing degree), and relative humidity. This paper will describe ongoing efforts to evaluate, design and test a UV-air system based on first principles. Specific issues to be addressed in this work will include laboratory measurements of relevant kinetics (i.e., UV dose-response behavior) and numerical simulations designed to represent fluid mechanics and the radiation intensity field. UV dose-response behavior of test microorganism was measured using a laboratory (bench-scale) system. Target microorganisms (e.g., bacterial spores) were first applied to membrane filters at sub-monolayer coverage. The filters were then transferred to an environmental chamber at fixed relative humidity (RH) and allowed to equilibrate with their surroundings. Microorganisms were then subjected to UV exposure under a collimated beam. The experiment was repeated at RH values ranging from 20% to 100%. UV dose-response behavior was observed to vary with RH. For example, at 100% RH, a UV dose of 20 mJ/cm2 accomplished 90% (1 log10 units) of the B. subtilis spore inactivation, whereas 99 % (2 log10 units) inactivation was accomplished at this same UV dose under 20% RH conditions. However, at higher doses, the result was opposite of that in low dose. Reactor behavior is simulated using an integrated application of computational fluid dynamics (CFD) and radiation intensity field models. These simulations followed a Lagrangian approach, wherein the UV radiation intensity field was mapped onto simulated particle trajectories for prediction of the UV dose delivered to each particle. By repeating these calculations for a large number of simulated particle trajectories, an estimate of the UV dose distribution delivered by the reactor can be made. In turn, these dose distribution estimates are integrated with the UV dose-response behavior described above to yield an estimate of microbial inactivation accomplished by the reactor. This modeling approach has the advantage of allowing simulation of many reactor configurations in a relatively short period of time. Moreover, by following this approach of "numerical prototyping," it is possible to "build" and analyze several virtual reactors before the construction of a physical prototype. As such, this procedure allows effective development of efficient reactors.

  12. Optimization of a greener method for removal phenol species by cloud point extraction and spectrophotometry.

    PubMed

    Zain, N N M; Abu Bakar, N K; Mohamad, S; Saleh, N Md

    2014-01-24

    A greener method based on cloud point extraction was developed for removing phenol species including 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TCP) and 4-nitrophenol (4-NP) in water samples by using the UV-Vis spectrophotometric method. The non-ionic surfactant DC193C was chosen as an extraction solvent due to its low water content in a surfactant rich phase and it is well-known as an environmentally-friendly solvent. The parameters affecting the extraction efficiency such as pH, temperature and incubation time, concentration of surfactant and salt, amount of surfactant and water content were evaluated and optimized. The proposed method was successfully applied for removing phenol species in real water samples. PMID:24161875

  13. Optimization of a greener method for removal phenol species by cloud point extraction and spectrophotometry

    NASA Astrophysics Data System (ADS)

    Zain, N. N. M.; Abu Bakar, N. K.; Mohamad, S.; Saleh, N. Md.

    2014-01-01

    A greener method based on cloud point extraction was developed for removing phenol species including 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TCP) and 4-nitrophenol (4-NP) in water samples by using the UV-Vis spectrophotometric method. The non-ionic surfactant DC193C was chosen as an extraction solvent due to its low water content in a surfactant rich phase and it is well-known as an environmentally-friendly solvent. The parameters affecting the extraction efficiency such as pH, temperature and incubation time, concentration of surfactant and salt, amount of surfactant and water content were evaluated and optimized. The proposed method was successfully applied for removing phenol species in real water samples.

  14. Bioassay and dose measurement in UV disinfection.

    PubMed Central

    Qualls, R G; Johnson, J D

    1983-01-01

    A bioassay method was developed to measure the average intensity within a UV disinfection reactor. The survival of spores of Bacillus subtilis was determined as a function of UV dose to prepare a standard curve. Spores were added to unknown systems, and the survival rate was used to determine the average intensity. A modification was used for flow-through reactors by which spores were injected as a spike and collected at a known time after injection. A point source summation method for calculating intensity was verified by bioassay measurements in a simple cylinder. This calculation method was also applied to multiple-lamp reactors. PMID:6405690

  15. Spectrophotometric and spectrodensitometric determination of Clopidogrel Bisulfate with kinetic study of its alkaline degradation.

    PubMed

    Zaazaa, Hala E; Abbas, Samah S; Abdelkawy, M; Abdelrahman, Maha M

    2009-05-15

    Four sensitive, selective and precise stability-indicating methods for the determination of Clopidogrel Bisulfate (CLP) in presence of its alkaline degradate and in pharmaceutical formulations were developed and validated. Method A is a second derivative (D(2)) spectrophotometric one, which allows the determination of CLP in presence of its alkaline degradate at 219.6, 270.6, 274.2 and 278.4 nm (corresponding to zero-crossing of the degradate) over a concentration range of 4-37 microg mL(-1) with mean percentage recoveries 99.81+/-0.893, 99.72+/-0.668, 99.88+/-0.526 and 100.46+/-0.646, respectively. CLP can be determined in the presence of up to 65% of its degradate. D(2) method was used to study the kinetic of CLP alkaline degradation that was found to follow a first-order reaction. The t(1/2) was 6.42 h while K (reaction rate constant) was 0.1080 mol/h. Method B is the first derivative of the ratio spectra (DD(1)) spectrophotometric method, by measuring the peak amplitude at 217.6 and 229.4 nm using acetonitrile and CLP can be determined in the presence of up to 70% of its degradate. The linearity range was 5-38 microg mL(-1) with mean percentage recoveries 99.88+/-0.909 and 99.70+/-0.952, respectively. Method C based on the determination of CLP by the bivariate calibration depending on simple mathematic algorithm which provides simplicity and rapidity. The method depends on quantitative evaluation of the absorbance at 210 and 225 nm over a concentration range 5-38 microg mL(-1) with mean percentage recovery 99.27+/-1.115. CLP can be determined in the presence of up to 70% of its degradate. Method D is a TLC-densitometric one, where CLP was separated from its degradate on silica gel plates using hexane:methanol:ethyl acetate (8.7:1:0.3, v/v/v) as a developing system. This method depends on quantitative densitometric evaluation of thin layer chromatogram of CLP at 248 nm over a concentration range of 0.6-3 microg/band with mean percentage recovery 99.97+/-1.161. CLP can be determined in the presence of up to 90% of its alkaline degradate. The selectivity of the proposed methods was checked using laboratory prepared mixtures. The proposed methods have been successfully applied to the analysis of CLP in pharmaceutical dosage forms without interference from other dosage form additives and the results were statistically compared with the official method. PMID:19269444

  16. Qualitative Aspects of UV-Vis Spectrophotometry of Beta-Carotene and Lycopene.

    ERIC Educational Resources Information Center

    Tan, Barrie; Soderstrom, David N.

    1989-01-01

    Explores the structural behavior of polyenic pi systems such as isomerization and conjugation. Uses the simultaneous spectrophotometric analysis of a beta-carotene and lycopene mixture. Presents an empirical method to determine the number of double bonds in the polyenic carotenoid. (MVL)

  17. Degradation of antipyrine by UV, UV/H?O? and UV/PS.

    PubMed

    Tan, Chaoqun; Gao, Naiyun; Deng, Yang; Zhang, Yongji; Sui, Minghao; Deng, Jing; Zhou, Shiqing

    2013-09-15

    Degradation of antipyrine (AP) in water by three UV-based photolysis processes (i.e., direct UV, UV/H?O?, UV/persulfate (UV/PS)) was studied. For all the oxidation processes, the AP decomposition exhibited a pseudo-first-order kinetics pattern. Generally, UV/H?O? and UV/PS significantly improved the degradation rate relevant to UV treatment alone. The pseudo-first-order degradation rate constants (kobs) were, to different degrees, affected by initial AP concentration, oxidant dose, pH, UV irradiation intensity, and co-existing chemicals such as humic acid, chloride, bicarbonate, carbonate and nitrate. The three oxidation processes followed the order in terms of treatment costs: UV/PS>UV>UV/H?O? if the energy and chemical costs are considered. Finally, the AP degradation pathways in the UV/H?O? and UV/PS processes are proposed. Results demonstrated that UV/H?O? and UV/PS are potential alternatives to control water pollution caused by emerging contaminants such as AP. PMID:23892168

  18. Interaction of diazepam with surfactants. Spectrophotometric and spectrofluorometric study

    NASA Astrophysics Data System (ADS)

    De La Guardia, M.; Rodilla, F.

    1986-03-01

    The interaction of diazepam with non-ionic, anionic and cationic surfactants has been studied spectrophotometrically and fluorometrically. It has been verified that the absorption spectrum of diazepam is not modified in micellar medium. However, a dramatic five-fold increase in fluorescence sensitivity is observed in the presence of sodium lauryl sulphate (SDS). The experimental conditions, temperature, pH and surfactant concentration have been optimized to improve the fluorometric determination of diazepam and a detection limit of 0,04 ppmhas been obtained.

  19. Spectrophotometric determination of molybdenum in rocks with thiocyanate

    USGS Publications Warehouse

    Lillie, E.G.; Greenland, L.P.

    1974-01-01

    A rapid procedure for the determination of microgram amounts of molybdenum in rocks is described. After acid decomposition, molybdenum is extracted from a hydrochloric acid solution into xylene with tributyl phosphate. After back-extraction with water, molybdenum is extracted as the ??-benzoinoximate into chloroform, stripped into hydrochloric acid extracted as the thiocyanate into amyl alcohol, and determined spectrophotometrically. The molybdenum thiocyanate color produced is stable, sensitive, and reproducible. Results of analyses of several of the U.S. Geological Survey standard rocks are given. ?? 1974.

  20. UV light induced photodegradation of organic dye by ZnO nanocatalysts

    NASA Astrophysics Data System (ADS)

    Sumesh, C. K.; Patel, Bhavin; Parekh, Kinnari

    2013-06-01

    Ultraviolet light induced photocatalytic activity of ZnO nanocatalyst prepared using a wet chemical precipitation route and mineralization of the methyl orange (MO) dye has been carried out in a photocatalytic reactor. The degradation of the MO was monitored spectrophotometrically and showed a decolorization efficiency of 92% after nine hours of irradiation in the MO-ZnO/UV light system. The blue shifting of maximum peak position of the MO and the formation of extra peak at 247 nm during irradiation time advances revealed that MO degrades in the form of intermediates during the photocatalytic process.

  1. Environmental UV photobiology

    SciTech Connect

    Young, A.R.; Bjoern, L.O.; Moan, J.; Nultsch, W. [eds.

    1993-12-31

    This book looks at the global depletion of stratospheric ozone and the consequences of the predicted increases of solar ultraviolet radiation. The introductory chapter deals with a characterization of solar UV-B and how radiation in this waveband can be influenced by ozone reduction in different locations. Two chapters deal with some technical aspects of measuring and simulating solar UV-B radiation. Seven chapters deal with the adverse effects of various aspects of human health that are anticipated in response to a change in level of solar UV-B, four dealing specifically with skin cancer. Two chapters address the basic aspects of ultraviolet photobiology, and finally the book addresses the implications of ozone reduction for aquatic ecosystems and for terrestrial plants.

  2. Kinetics of UV inactivation of wastewater bioflocs.

    PubMed

    Azimi, Y; Allen, D G; Farnood, R R

    2012-08-01

    Ultraviolet disinfection is a physical method of disinfecting secondary treated wastewaters. Bioflocs formed during secondary treatment harbor and protect microbes from exposure to ultraviolet (UV) light, and significantly decrease the efficiency of disinfection at high UV doses causing the tailing phenomena. However, the exact mechanism of tailing and the role of biofloc properties and treatment conditions are not widely understood. It is hypothesized that sludge bioflocs are composed of an easily disinfectable loose outer shell, and a physically stronger compact core inside that accounts for the tailing phenomena. Hydrodynamic shear stress was applied to the bioflocs to peel off the looser outer shell to isolate the cores. Biofloc and core samples were fractionated into narrow size distributions by sieving and their UV disinfection kinetics were determined and compared. The results showed that for bioflocs, the tailing level elevates as the biofloc size increases, showing greater resistance to disinfection. However, for the cores larger than 45?m, it was found that the UV inactivation curves overlap, and show very close to identical inactivation kinetics. Comparing bioflocs and cores of similar size fraction, it was found that in all cases cores were harder to disinfect with UV light, and showed a higher tailing level. This study suggests that physical structure of bioflocs plays a significant role in the UV inactivation kinetics. PMID:22608608

  3. Reconstruction techniques of erythemal UV-radiation and future UV predictions

    NASA Astrophysics Data System (ADS)

    Wagner, J. E.; Rieder, H. E.; Simic, S.; Weihs, P.

    2009-04-01

    Since the discovery of anthropogenic ozone depletion more than 30 year ago, the scientific community has shown an increasing interest in UV-B radiation and started to monitor UV-radiation. However, difficulties involved in the routine operation and maintenance of the instruments have limited the length of reliable data records to about two decades. Further the number of places where they were measured, resulting in a set of observations too short and too sparse for a good understanding of past UV changes. Moreover state of the art climate models do not calculate future scenarios of UV-doses. Therefore detailed information about past and future UV-trends are lacking. Reconstruction techniques are indispensable to derive long-term time series of UV-radiation and fill this gap. Apart from the astronomical parameters, like solar zenith angle and sun-earth-distance, UV radiation is strongly influenced by clouds, ozone and surface albedo. We developed and evaluated a reconstruction technique for UV-doses that first calculates the UV-doses under clear-sky condition and afterwards applies corrections in order to take cloud effects into account. Since the input parameters cloud cover, total ozone column and surface albedo are available from the Regional Climate Model (REMO), we applied our reconstruction technique also for future scenarios using REMO data as input. Hence we are able to derive a seamless UV long-term time series from the past to the future. Our method was applied for the high alpine station Hoher Sonnblick (3108m) situated in Austrian Alps.

  4. Spectrophotometric Determination of Mycophenolate Mofetil as Its Charge-Transfer Complexes with Two ?-Acceptors

    PubMed Central

    Vinay, K. B.; Revanasiddappa, H. D.; Raghu, M. S.; Abdulrahman, Sameer. A. M.; Rajendraprasad, N.

    2012-01-01

    Two simple, selective, and rapid spectrophotometric methods are described for the determination of mycophenolate mofetil (MPM) in pure form and in tablets. Both methods are based on charge-transfer complexation reaction of MPM with p-chloranilic acid (p-CA) or 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) in dioxane-acetonitrile medium resulting in coloured product measurable at 520 nm (p-CA) or 580?nm (DDQ). Beer's law is obeyed over the concentration ranges of 40–400 and 12–120??g?mL?1 MPM for p-CA and DDQ, respectively, with correlation coefficients (r) of 0.9995 and 0.9947. The apparent molar absorptivity values are calculated to be 1.06 × 103 and 3.87 × 103?L?mol?1?cm?1, respectively, and the corresponding Sandell's sensitivities are 0.4106 and 0.1119??g?cm?1. The limits of detection (LOD) and quantification (LOQ) are also reported for both methods. The described methods were successfully applied to the determination of MPM in tablets. Statistical comparison of the results with those of the reference method showed excellent agreement. No interference was observed from the common excipients present in tablets. Both methods were validated statistically for accuracy and precision. The accuracy and reliability of the methods were further ascertained by recovery studies via standard addition procedure. PMID:22567572

  5. Epidermal UV-screening in vascular plants from Svalbard (Norwegian Arctic)

    Microsoft Academic Search

    Line Nybakken; Wolfgang Bilger; Ulf Johanson; LarsOlof Björn; Mathias Zielke; Bjørn Solheim

    2004-01-01

    Stratospheric ozone depletion is most pronounced at high latitudes, and the concurring increased UV-B radiation might adversely affect plants from polar areas. However, vascular plants may protect themselves against UV-B radiation by UV-absorbing compounds located in the epidermis. In this 3-year study, epidermal UV-B (? max 314 nm) and UV-A (? max 366 nm) screening was assessed using a fluorescence method in

  6. A new weight factor spectrophotometric computer color matching

    NASA Astrophysics Data System (ADS)

    Song, Dongcao; Wang, Xichang; Gong, Yanjun; Yang, Shangming; Liang, Fangying

    2005-02-01

    On the basis of spectrophotometric color matching, the color difference weight factor is proposed and used in the thesis. The weight factor can be expressed as ?j = {{[(x(?j)]2 + [y(?j)]2 + [z(?j)]2}[S(?j)]2}» and obtained according to the assumption of ?j(?Xj)2+(?Yj)2+(?Zj)2 -> min, i. e., in the range of visible spectrum it is assumed that the square sum of tri-stimulus value deviation produced by spectrum deviation at each wavelength is minimal.Through comparison with spectrophotometric color matching, we find a new weight factor. The new factor multiplied by the variety of reflectivity is the color difference, which is cause by the difference of reflectivity between standard color and matching color. So we name the weight factor: color difference weight factor. The prediction of computer shows the color difference produced by the weight factor is smaller than that produced by the two weight factors which were designed by Schmid and Strockash.

  7. Far UV camera \\/FAUST

    Microsoft Academic Search

    G. Riviere; J.-M. Deharveng

    1978-01-01

    This instrument consists of a Wynne telescope coupled with an image detector including an ultraviolet image intensifier with film recording. The resolution is about 2 arcmin. Owing to its large field (7.5 deg) and high sensitivity (limiting magnitude of 17), this camera is well suited for far-UV deep surveys; it will be flown on the first Spacelab flight.

  8. Are You UV Safe?

    ERIC Educational Resources Information Center

    Capobianco, Brenda; Thiel, Elizabeth Andrew

    2006-01-01

    Students may be slathered with SPF 30 sunscreen all summer at the beach or pool, but what do they know about ultraviolet (UV) light radiation and absorption? The authors of this article found the perfect opportunity to help students find out the science behind this important health precaution, when they developed a series of practical strategies…

  9. Chemical consequences of radioactive decay. 2. Spectrophotometric study of the ingrowth of berkelium-249 and californium-249 into halides of einsteinium-253

    Microsoft Academic Search

    J. P. Young; R. G. Haire; J. R. Peterson; D. D. Ensor; R. L. Fellows

    1981-01-01

    The ingrowth of ²⁴⁹Bk daughter and ²⁴⁹Cf granddaughter into fluorides, chlorides, bromides, and iodides of parent ²⁵³Es was followed by spectrophotometric methods. In the case of trivalent Es halides, the oxidation state of the parent is maintained by its progeny. In the case of divalent Es halides, the oxidation state of the parent is retained by the granddaughter species. No

  10. Spectrophotometric determination of trace ionic and non-ionic surfactants based on a collection on a membrane filter as the ion associate of the surfactant with Erythrosine B

    Microsoft Academic Search

    Koichi Yamamoto; Masato Oka; Haruo Murakami

    2002-01-01

    The spectrophotometric method for the determination of trace surfactants with Erythrosine B (EB) based on the aqueous reaction and the collection on a membrane filter by filtration was studied. Cationic surfactants (CS+), such as a quaternary ammonium ion, and polyoxyethylene non-ionic surfactants (NS) in the presence of potassium ion, containing a long-chain alkyl group associate with EB buffered at pH

  11. Comparison of visual 24-hour and spectrophotometric 48-hour MICs to CLSI reference microdilution MICs of fluconazole, itraconazole, posaconazole, and voriconazole for Candida spp.: a collaborative study

    Microsoft Academic Search

    A. Espinel-Ingroff; F. Barchiesi; M. Cuenca-Estrella; A. Fothergill; M. A. Pfaller; M. Rinaldi; J. L. Rodriguez-Tudela; P. E. Verweij

    2005-01-01

    A multicenter (six-center) study evaluated the performance (interlaboratory reproducibility, compatibility with reference methods, and categorical agreement) of 24-h visual and 48-h spectrophotometric MICs. MICs of fluconazole, itraconazole, voriconazole, and posaconazole were compared to reference 48-h microdilution broth visual MICs (CLSI [formerly NCCLS] M27-A2 document) for 71 isolates of Candida spp. that included 10 fluconazole-resistant strains. Twenty readings (5%) were reported

  12. Copper(II)-catalysed oxidative coupling reaction of 3-hydroxyacetanilide with 3-methyl-2-benzothiazolinone hydrazone for the spectrophotometric determination of traces of copper(II)

    Microsoft Academic Search

    M. S. Hemantha Kumar; P. Nagaraja; H. S. Yathirajan

    2003-01-01

    A spectrophotometric method is developed for the determination of traces of copper(II), based on the catalytic oxidative coupling reaction of 3-hydroxyacetanilide with 3-methyl-2-benzothiazolinone hydrazone in the presence of ammonia and hydrochloric acid. Beer's law is obeyed in the copper(II) concentration range of 0.008-0.16 wg mLу, and the molar absorptivity at 530 nm is 2.5쎹 L molу cmу. The Sandell's sensitivity

  13. Rapid automated assay of anti-oxidation\\/radical-scavenging activity of natural substances by sequential injection technique (SIA) using spectrophotometric detection

    Microsoft Academic Search

    Miroslav Polášek; Petr Skála; Lubomír Opletal; Lud?k Jahodá?

    2004-01-01

    A PC-controlled sequential injection analysis (SIA) system equipped with a spectrophotometric diode-array detector is used for rapid monitoring and evaluation of antioxidation\\/radical scavenging activity of biological samples. The automated method is based on the known reaction of stable 2,2?-diphenyl-1-picrylhydrazyl radical (DPPH) with antioxidants in organic or aqueous-organic media resulting in bleaching of DPPH due to its “quenching” by the interaction

  14. Standard test methods for chemical, mass spectrometric, spectrochemical, nuclear, and radiochemical analysis of nuclear-grade plutonium nitrate solutions

    E-print Network

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 These test methods cover procedures for the chemical, mass spectrometric, spectrochemical, nuclear, and radiochemical analysis of nuclear-grade plutonium nitrate solutions to determine compliance with specifications. 1.2 The analytical procedures appear in the following order: Sections Plutonium by Controlled-Potential Coulometry Plutonium by Amperometric Titration with Iron(II) Plutonium by Diode Array Spectrophotometry Free Acid by Titration in an Oxalate Solution 8 to 15 Free Acid by Iodate Precipitation-Potentiometric Titration Test Method 16 to 22 Uranium by Arsenazo I Spectrophotometric Test Method 23 to 33 Thorium by Thorin Spectrophotometric Test Method 34 to 42 Iron by 1,10-Phenanthroline Spectrophotometric Test Method 43 to 50 Impurities by ICP-AES Chloride by Thiocyanate Spectrophotometric Test Method 51 to 58 Fluoride by Distillation-Spectrophotometric Test Method 59 to 66 Sulfate by Barium Sulfate Turbidimetric Test Method 67 to 74 Isotopic Composition by Mass Spectrom...

  15. A new coupling of spectrophotometric determination with ultrasound-assisted emulsification dispersive liquid-liquid microextraction of trace silver

    NASA Astrophysics Data System (ADS)

    Wen, Xiaodong; Kong, Lamei; Chen, Meihui; Deng, Qingwen; Zhao, Xia; Guo, Jie

    2012-11-01

    In this work, a new coupling of spectrophotometric determination with preconcentration method named as ultrasound-assisted emulsification dispersive liquid-liquid microextraction (UAE-DLLME) for trace silver was firstly established. Disperser solvent in traditional DLLME was substituted by ultrasound-assisted emulsification, which could afford more effective emulsification and make the extraction method greener. The extraction was accomplished efficiently in only 3 min during ultrasound-assisted emulsification. Compared to traditional DLLME, the established pretreatment was simpler, greener and more effective. The UAE-DLLME technique was effectively coupled with ordinary spectrophotometer to improve the analytical performance and expand the application of spectrophotometric determination. The factors influencing UAE-DLLME, such as concentration of chelating agent, kind and volume of extractant, pH, conditions of phase separation, ultrasound extraction time and instrumental conditions, were studied in detail. Under the optimal conditions, the limit of detection (LOD) for silver was 0.45 ?g L-1, with sensitivity enhancement factor (EF) of 35. The established method was applied to the determination of trace silver in real and certified reference samples with satisfactory analytical results.

  16. Spectrophotometric study of the charge-transfer and ion-pair complexation of methamphetamine with some acceptors

    NASA Astrophysics Data System (ADS)

    Shahdousti, Parvin; Aghamohammadi, Mohammad; Alizadeh, Naader

    2008-04-01

    The charge-transfer (CT) complexes of methamphetamine (MPA) as a n-donor with several acceptors including bromocresolgreen (BCG), bromocresolpurple (BCP), chlorophenolred (CPR), picric acid (PIC), and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) have been studied spectrophotometrically in chloroform solutions in order to obtain some information about their stoichiometry and stability of complexation. The oscillator strengths, transition dipole moments and resonance energy of the complex in the ground state for all complexes have been calculated. Vertical ionization potential of MPA and electron affinity of acceptors were determined by ab initio calculation. The acceptors were also used to utilize a simple and sensitive extraction-spectrophotometric method for the determination of MPA. The method is based on the formation of 1:1 ion-pair association complexes of MPA with BCG, BCP and PIC in chloroform medium. Beer's plots were obeyed in a general concentration range of 0.24-22 ?g ml -1 for the investigated drug with different acceptors. The proposed methods were applied successfully for the determination of MAP in pure and abuse drug with good accuracy and precision.

  17. The UV Sky Surveys: a Roadmap for Future UV Missions

    E-print Network

    Bianchi, Luciana

    The UV Sky Surveys: a Road­map for Future UV Missions Luciana Bianchi #3; , Boryana Efremova #3, Baltimore, USA + INAF, Astronomical Observatory of Padua, Italy Abstract. Surveys of the sky in two bands surveys and the resulting catalogs of UV sources, linked to a multi­wavelength archive, allow us to detect

  18. Spectrophotometric Determination of N-Acetyl-L-Cysteine and N-(2-Mercaptopropionyl)-Glycine in Pharmaceutical Preparations

    PubMed Central

    Kukoc-Modun, Lea; Radi?, Njegomir

    2011-01-01

    A simple spectrophotometric method for the determination of N-acetyl-L-cysteine (NAC) and N-(2-mercaptopropionyl)glycine (MPG) in pharmaceutical preparations was developed, validated, and used. The proposed equilibrium method is based on a coupled two-step redox and complexation reaction. In the first step, Fe(III) is reduced to Fe(II) by NAC or MPG. Subsequently, Fe(II) is complexed with 2,4,6-tripyridyl-s-triazine (TPTZ). Several analytical parameters of the method were optimized for NAC and MPG analysis in the concentration range from 1.0??M to 100.0??M. Regression analysis of the calibration data showed a good correlation coefficient (0.9999). The detection limit of the method was 0.14??M for NAC and 0.13??M for MPG. The method was successfully applied to quantify NAC and MPG in pharmaceutical preparations. No interferences were observed from common pharmaceutical excipients. PMID:21647283

  19. UVS is rare in seabirds

    Microsoft Academic Search

    Gabriel E. Machovsky Capuska; Leon Huynen; David Lambert; David Raubenheimer

    2011-01-01

    Ultraviolet-sensitive vision (UVS), believed to have evolved from an ancestral state of violet-sensitive vision (VS), is widespread among terrestrial birds, where it is thought to play a role in orientation, foraging, and sexual selection. Less is known, however, about the distribution and significance of UVS in seabirds. To date UVS has been definitively demonstrated only in two families (Laridae and

  20. UV immobilized phospholipid bilayers

    Microsoft Academic Search

    E UZGIRIS

    1987-01-01

    Dinitrophenyl phosphotidylethanolamine-containing bilayers have been immobilized on carbon-shadowed support films by UV irradiation of the first monolayer transferred to the support film. The immobilized bilayer is capable of allowing bound protein (anti-DNP antibody) to organize into 2-D arrays in the presence of organic solvents such as acetonitrile and dilute concentrations of detergents such as beta-octyl glucoside. The ability of the

  1. Ultrasound-assisted cloud point extraction for speciation and indirect spectrophotometric determination of chromium(III) and (VI) in water samples

    NASA Astrophysics Data System (ADS)

    Hashemi, Mahdi; Daryanavard, Seyed Mosayeb

    Ultrasound-assisted cloud point extraction (UACPE) procedure was developed for speciation and indirect spectrophotometric determination of chromium(III) and (VI) in environmental water samples. The method is based on the reduction of Cr(VI) by iodide in acidic media and subsequently formation of I3- anion. The I3- formed can further react with cetyltrimethylammonium bromide (CTAB) and induce its clouding due to formation of an ion-association complex. The formed complex was separated from solution and dissolved in ethanol for spectrophotometric measurement. Cerium(IV) ammonium sulphate was chosen as an oxidizing reagent for pre-oxidation step of Cr(III) to Cr(VI) species before the addition of iodide to the system, up to chromium in trivalent can be determined by the procedure. Experimental parameters for both spectrophotometric reaction and extraction procedure have been optimized. Under optimized conditions Cr(VI) can be determined in the range 20-400 ng mL-1 (R2 = 0.999). Detection limit, preconcentration factor and relative standard deviation were 12 ng mL-1, 20.0 and 2.2% (n = 5), respectively with 10 mL sample volumes. The proposed method has been successfully applied for determination of chromium(V) in spiked water, synthetic seawater and electroplating wastewater samples with average recoveries of 100.1, 99.4 and 99.1%, respectively.

  2. UV\\/ozone cleaning of surfaces

    Microsoft Academic Search

    J. R. Vig; J. W. Lebus

    1976-01-01

    The UV ozone cleaning procedure is shown to be an effective method of rapidly removing a variety of contaminants from surfaces. It is a simple-to-use dry process which is inexpensive to set up and operate. It can produce clean surfaces in air, at ambient temperatures. The experiments were performed on quartz and metal surfaces. The contaminants which were successfully removed

  3. UV\\/Ozone Cleaning of Surfaces

    Microsoft Academic Search

    JOHN R. VIG; J. LeBus

    1976-01-01

    The ultraviolet (UV)\\/ozone cleaning procedure is shown to be an effective method of rapidly removing a variety of contaminants from surfaces. It is a simple-to-use dry process which is inexpensive to set up and operate. It can produce · clean surfaces in air, at ambient temperatures. The experiments were performed on quartz and metal surfaces. The contaminants which were successfully

  4. Floatation-spectrophotometric Determination of Thorium, Using Complex Formation with Eriochrome Cyanine R

    PubMed Central

    Shiri, Sabah; Delpisheh, Ali; Haeri, Ali; Poornajaf, Abdolhossein; Khezeli, Tahereh; Badkiu, Nadie

    2011-01-01

    A novel and sensitive floatation-spectrophotometric method is presented for determination of trace amounts of thorium in water samples. The method is based on the ion-associated formation between thorium, Eriochrome cyanine R and Brij-35 at pH = 4 media. The complex was floated in the interface of the aqueous phase and n-hexane by vigorous shaking. After removing the aqueous phase the floated particles were dissolved in methanol and the absorbance was measured at 607 nm. The influence of different important parameters such as Eriochrome cyanine R and surfactants concentration, pH, volume of n-hexane, standing time and interfering ions were evaluated. Under optimized conditions the calibration graph was linear in the range of 6–230 ng mL?1 of thorium with a correlation coefficient of 0.9985. The limit of detections (LOD), based on signal to noise ratio (S/N) of 3 was 1.7 ng mL?1. The relative standard deviations for determination of 150 and 30 ng ml?1 of thorium were 3.26 and 4.41%, respectively (n = 10). The method showed a good linearity, recoveries, as well as some advantages such as sensitivity, simplicity, affordability and a high feasibility. The method was successfully applied to determine thorium in different water and urine samples. PMID:21340019

  5. Spectrophotometric determination of norepinephrine with sodium iodate and determination of its acidity constants

    NASA Astrophysics Data System (ADS)

    Hashem, E. Y.; Youssef, A. K.

    2013-05-01

    A spectrophotometric method is proposed for the determination of norepinephrine (NE) and its bitartrate salts. The method was based on the development of a red color (?max = 495 nm) with sodium iodate in aqueous alcoholic medium at pH 5. The color was stable for at least 4 hrs. The molar reacting ratio of NE to sodium iodate was 1:4. A linear relationship was obtained between the absorption intensity and NE concentration in the range of 3.384-37.224 ?g/ml with detection limit of 0.067 ?g/ml and correlation coefficient of 0.9972. The present work facilitated the determination of the three acidity constants, 7.564 ± 0.02, 9.036 ± 0.034, and 10.761 ± 0.023. The reaction mechanism was also described. The proposed method was successfully applied for the determination of NE in pharmaceutical formulations. Results for analysis of bulk drugs and injections agree with those of official methods.

  6. Determination of ammonia in beers by pervaporation flow injection analysis and spectrophotometric detection.

    PubMed

    Wang, Lijuan; Cardwell, Terence J; Cattrall, Robert W; Luque de Castro, Maria D; Kolev, Spas D

    2003-08-29

    A pervaporation flow injection (PFI) method is described for the determination of ammonia in beers. After injecting the sample into a NaOH donor solution, ammonia and other volatiles are transferred in the pervaporation unit from the donor stream to an acceptor stream containing sodium salicylate and nitroprusside, which subsequently mixes with alkaline sodium dichloroisocyanurate to allow the classical Berthelot reaction to take place. The blue-coloured complex formed is monitored spectrophotometrically at 655 nm. A linear calibration curve with a range of 0.1-40 mg l(-1) was obtained. The method has a detection limit of 0.05 mg l(-1) and is capable of a sampling frequency of 11 h(-1) at 4 mg l(-1) ammonia. It was applied successfully to the determination of ammonia in synthetic samples and unfiltered lager beers. The advantages of the present method over the ammonia ion-selective electrode method and the PFI system based on mixed indicator detection are discussed. PMID:18969154

  7. Spectrophotometric determination of ?-adrenergic antagonists drugs via ion-pair complex formation using MO and EBT

    NASA Astrophysics Data System (ADS)

    El-Didamony, A. M.; Shehata, A. M.

    2014-09-01

    Two simple, rapid and sensitive spectrophotometric methods have been proposed for the assay of bisoprolol fumarate (BSF), propranolol hydrochloride (PRH), and timolol maleate (TIM) either in bulk or in pharmaceutical formulations. The methods are based on the reaction of the selected drugs with methyl orange (MO) and eriochrome black T in acidic buffers, after extracting in dichloromethane and measured quantitatively with maximum absorption at 428 and 518 nm for MO and EBT, respectively. The analytical parameters and their effects on the reported systems are investigated. The extracts are intensely colored and very stable at room temperature. The calibration graphs were linear over the concentration range of 0.8-6.4, 0.4-3.6, 0.8-5.6 ?g/mL for BSF, PRH, and TIM, respectively, with MO and 0.8-6.4, 0.4-3.2, and 0.8-8.0 ?g/mL for BSF, PRH, and TIM, respectively, with EBT. The stoichiometry of the complexes was found to be 1 : 1 in all cases. The proposed methods were successfully extended to pharmaceutical preparations. Excipients used as additive in commercial formulations did not interfere in the analysis. The proposed methods can be recommended for quality control and routine analysis where time, cost effectiveness and high specificity of analytical technique are of great importance.

  8. Additional studies for the spectrophotometric measurement of iodine in water

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Previous work in iodine spectroscopy is briefly reviewed. Continued studies of the direct spectrophotometric determination of aqueous iodine complexed with potassium iodide show that free iodine is optimally determined at the isosbestic point for these solutions. The effects on iodine determinations of turbidity and chemical substances (in trace amounts) is discussed and illustrated. At the levels tested, iodine measurements are not significantly altered by such substances. A preliminary design for an on-line, automated iodine monitor with eventual capability of operating also as a controller was analyzed and developed in detail with respect single beam colorimeter operating at two wavelengths (using a rotating filter wheel). A flow-through sample cell allows the instrument to operate continuously, except for momentary stop flow when measurements are made. The timed automatic cycling of the system may be interrupted whenever desired, for manual operation. An analog output signal permits controlling an iodine generator.

  9. A chiral HPLC-UV method for the quantification of dibenz[b,f]azepine-5-carboxamide derivatives in mouse plasma and brain tissue: eslicarbazepine acetate, carbamazepine and main metabolites.

    PubMed

    Fortuna, Ana; Bicker, Joana; Alves, Gilberto; Falcão, Amílcar; Soares-da-Silva, Patrício

    2011-06-01

    For the first time, a selective and sensitive chiral HPLC-UV method was developed and fully validated for the simultaneous quantification of eslicarbazepine acetate (ESL), carbamazepine (CBZ), S-licarbazepine (S-Lic), R-licarbazepine (R-Lic), oxcarbazepine (OXC) and carbamazepine-10,11-epoxide (CBZ-E), in mouse plasma and brain homogenate supernatant. After the addition of chloramphenicol as the internal standard, samples were processed using an SPE procedure. The chiral chromatographic analysis was carried out on a LiChroCART 250-4 ChiraDex column, employing a mobile phase of water and methanol (88:12, v/v) pumped at 0.9 mL/min and the UV detector set at 235 nm. The assay was linear (r(2) ?0.995) for ESL, CBZ, OXC, S-Lic, R-Lic and CBZ-E in the range of, respectively, 0.2-4, 0.4-30, 0.1-60, 0.2-60, 0.2-60 and 0.2-30 ?g/mL, in plasma, and of 0.06-1.5 ?g/mL for ESL, 0.12-15 ?g/mL for CBZ and CBZ-E and 0.06-15 ?g/mL for OXC and both licarbazepine (Lic) enantiomers in brain homogenate supernatant. The overall precision was within 8.71% and accuracy ranged from -7.55 to 8.97%. The recoveries of all the compounds were over 92.1%. Afterwards, the application of the method was demonstrated using real plasma and brain samples obtained from mice administered simultaneously with ESL and CBZ. PMID:21557472

  10. UNIT 13.3BEMS and UV Mutagenesis in Yeast Fred Winston1

    E-print Network

    Winston, Fred

    methanesulfate (EMS) and ultraviolet (UV) light. Each of these methods has been used successfully for many years methanesulfonate (EMS) and ultraviolet (UV) light. Mutagenesis can increase the frequency of mutation up to 100

  11. Validated method for the determination of piroxicam by capillary zone electrophoresis and its application to tablets.

    PubMed

    Dal, Ar?n Gül; Oktayer, Zeynep; Do?rukol-Ak, Dilek

    2014-01-01

    Simple and rapid capillary zone electrophoretic method was developed and validated in this study for the determination of piroxicam in tablets. The separation of piroxicam was conducted in a fused-silica capillary by using 10?mM borate buffer (pH 9.0) containing 10% (v/v) methanol as background electrolyte. The optimum conditions determined were 25?kV for separation voltage and 1?s for injection time. Analysis was carried out with UV detection at 204?nm. Naproxen sodium was used as an internal standard. The method was linear over the range of 0.23-28.79?µg/mL. The accuracy and precision were found to be satisfied within the acceptable limits (<2%). The LOD and LOQ were found to be 0.07 and 0.19?µg/mL, respectively. The method described here was applied to tablet dosage forms and the content of a tablet was found in the limits of USP-24 suggestions. To compare the results of capillary electrophoretic method, UV spectrophotometric method was developed and the difference between two methods was found to be insignificant. The capillary zone electrophoretic method developed in this study is rapid, simple, and suitable for routine analysis of piroxicam in pharmaceutical tablets. PMID:25295220

  12. Multi-wavelength spectrophotometric determination of acid dissociation constants: a validation study

    Microsoft Academic Search

    Kin Y Tam; Krisztina Takács-Novák

    2001-01-01

    The pKa values of 25 structurally diverse drug compounds including mono-, di- and tri-protic molecules were determined by a recently developed multi-wavelength spectrophotometric technique, called dip-probe absorption spectroscopy (D-PAS), and the traditional spectrophotometric titration. All experiments were performed at 25.0±0.5°C in an ionic strength of 0.15M KCl in two laboratories (Semmelweis and Sirius), to evaluate the reproducibility and reliability of

  13. Physical parameters of the continuum emission layer of Mira-type stars. I. Spectrophotometric temperatures

    Microsoft Academic Search

    E. V. Ruban; A. A. Arkharov; E. I. Hagen-Thorn; T. Yu. Puzakova

    2007-01-01

    The spectrophotometric temperatures of five Mira-type variable stars are determined using observations in the Pulkovo spectrophotometric\\u000a data base in the range from 320–1080 nm. All the resulting temperatures are below the effective temperatures of stars in the\\u000a corresponding subclasses. Near the brightness maximum, the temperatures are found to be lower with increasing separation in\\u000a time from the maximum.

  14. Visible spectrophotometric determination of tantalum in soil, sediment, minerals, and alloys.

    PubMed

    Patel, K S; Shukla, A; Agarwal, N; Hoffmann, P

    2001-01-01

    A new, sensitive, and selective method is described for the spectrophotometric determination of Ta(V). The method is based on the extraction of the Ta(V)-F-CV+ complex (CV+ = crystal violet cation) with a benzene solution of imidoyl derivatives (ID), i.e., N,N'-diphenylbenzamidine (DPBA), N-hydroxy-N,N'-diphenylbenzamidine, and N-(2,5-dimethyl)phenyl-p-tolylimidoylphenylhydrazine, from sulfuric acid solution; DPBA was selected for detailed study. The molar absorptivities of the Ta(V)-F-CV+-ID complexes in the benzene solution were in the range of (1.00-1.65) x 10(5) L/mol x cm at 600 nm. The limit of detection was 7 ng Ta/mL (which had an absorbance greater than that of the blank + 3 standard deviations). The optimization of the analytical variables, the composition of the complex, and the effect of diverse ions in the determination of Ta are discussed. The present method was applied to the determination of Ta in environmental samples, i.e., soil, sediment, minerals, and alloys. PMID:11324604

  15. A Continuous Spectrophotometric Assay for APS Reductase Activity with Sulfite-Selective Probes

    PubMed Central

    Paritala, Hanumantharao; Carroll, Kate S.

    2013-01-01

    Mycobacterium tuberculosis (Mtb) adenosine 5?-phosphosulfate (APS) reductase (EC number 1.8.4.10), (APR) catalyzes the first committed step in sulfate reduction for the biosynthesis of essential reduced sulfur-containing biomolecules, such as cysteine, and is essential for survival in the latent phase of TB infection. Despite the importance of APR to Mtb, and other bacterial pathogens, current assay methods depend on use of [35S]-labeled APS or shunt AMP to a coupled-enzyme system. Both methods are cumbersome and require the use of expensive reagents. Here we report the development of a continuous spectrophotometric method for measuring APR activity by using novel sulfite-selective colorimetric or “off-on” fluorescent levulinate-based probes. The APR activity can thus be followed by monitoring the increase in absorbance or fluorescence of the resulting phenolate product. Using this assay, we determined Michelis-Menten kinetic constants (Km, kcat, kcat/Km) and apparent inhibition constant (Ki) for adenosine 5?-diphosphate (ADP), which compared favorably to values obtained in the gold-standard radioactive assay. The newly developed assay is robust and easy to perform with a simple spectrophotometer. PMID:23711725

  16. Straightforward rapid spectrophotometric quantification of total cyanogenic glycosides in fresh and processed cassava products.

    PubMed

    Tivana, Lucas Daniel; Da Cruz Francisco, Jose; Zelder, Felix; Bergenståhl, Bjorn; Dejmek, Petr

    2014-09-01

    In this study, we extend pioneering studies and demonstrate straightforward applicability of the corrin-based chemosensor, aquacyanocobyrinic acid (ACCA), for the instantaneous detection and rapid quantification of endogenous cyanide in fresh and processed cassava roots. Hydrolytically liberated endogenous cyanide from cyanogenic glycosides (CNp) reacts with ACCA to form dicyanocobyrinic acid (DCCA), accompanied by a change of colour from orange to violet. The method was successfully tested on various cassava samples containing between 6 and 200 mg equiv. HCN/kg as verified with isonicotinate/1,3-dimethylbarbiturate as an independent method. The affinity of ACCA sensor to cyanide is high, coordination occurs fast and the colorimetric response can therefore be instantaneously monitored with spectrophotometric methods. Direct applications of the sensor without need of extensive and laborious extraction processes are demonstrated in water-extracted samples, in acid-extracted samples, and directly on juice drops. ACCA showed high precision with a standard deviation (STDV) between 0.03 and 0.06 and high accuracy (93-96%). Overall, the ACCA procedure is straightforward, safe and easily performed. In a proof-of-concept study, rapid screening of ten samples within 20 min has been tested. PMID:24731309

  17. A spectrophotometric flow injection system for streptomycin determination in veterinary samples

    NASA Astrophysics Data System (ADS)

    Frugeri, Pedro Marcos; Lago, Ayla Campos do; Wisniewski, Célio; Luccas, Pedro Orival

    2014-01-01

    In this work a spectrophotometric flow injection analysis system for streptomycin determination in veterinary samples, is being proposed. The method is based on streptomycin alkaline hydrolysis that forms guanidine, followed by the reaction with Fe(II). The colored product has absorption peak at 520 nm. To evaluate and optimize the system parameters, chemometrics tools, such as factorial design, Pareto chart and Doelhert design, were used. The veterinary samples are diluted in water and introduced in the FIA system, therefore no sample preparation is required. The optimized system presented: linear range of 60 up to 1000 mg L-1, limit of detection of 18 mg L-1 and sampling rate of 36 readings per hour. The precision was checked and the CV for veterinary sample readings were always less than 6.5%. The accuracy was studied by comparison with chromatographic method, thus, five samples of pharmaceutical veterinary were determined by HPLC and by the proposed method, and the results are in agreement (t-test, p = 0.05).

  18. A continuous spectrophotometric assay for adenosine 5'-phosphosulfate reductase activity with sulfite-selective probes.

    PubMed

    Paritala, Hanumantharao; Carroll, Kate S

    2013-09-01

    Mycobacterium tuberculosis (Mtb) adenosine 5'-phosphosulfate (APS) reductase (APR) catalyzes the first committed step in sulfate reduction for the biosynthesis of essential reduced sulfur-containing biomolecules, such as cysteine, and is essential for survival in the latent phase of tuberculosis (TB) infection. Despite the importance of APR to Mtb and other bacterial pathogens, current assay methods depend on the use of (35)S-labeled APS or shunt adenosine 5'-monophosphate (AMP) to a coupled-enzyme system. Both methods are cumbersome and require the use of expensive reagents. Here, we report the development of a continuous spectrophotometric method for measuring APR activity by using novel sulfite-selective colorimetric or "off-on" fluorescent levulinate-based probes. Thus, the APR activity can be followed by monitoring the increase in absorbance or fluorescence of the resulting phenolate product. Using this assay, we determined Michaelis-Menten kinetic constants (K(m), k(cat), and k(cat)/K(m)) and the apparent inhibition constant (Ki) for adenosine 5'-diphosphate (ADP), which compared favorably with values obtained in the "gold standard" radioactive assay. The newly developed assay is robust and easy to perform with a simple spectrophotometer. PMID:23711725

  19. Novel coupling of surfactant assisted emulsification dispersive liquid-liquid microextraction with spectrophotometric determination for ultra trace nickel

    NASA Astrophysics Data System (ADS)

    Deng, Qingwen; Chen, Meihui; Kong, Lamei; Zhao, Xia; Guo, Jie; Wen, Xiaodong

    2013-03-01

    In this work, dispersive liquid-liquid microextraction (DLLME) was improved and the preconcentration method named as surfactant assisted emulsification dispersive liquid-liquid microextraction (SAE-DLLME) was established for ultra trace nickel preconcentration and spectrophotometric determination. Non-ionic surfactant Triton X-100 (TX-100) was used as emulsifier and Triton X-114 (TX-114) was investigated as comparison. Disperser solvent was substituted by surfactant, which could afford more effective emulsification and make the extraction relatively greener. The extraction was accomplished efficiently in only 1 min during manual shaking. Compared to traditional DLLME, the developed SAE-DLLME pretreatment was simple, rapid and effective. The improved extraction technique was firstly coupled with traditional spectrophotometer to improve the analytical performance and expand the application of spectrophotometric determination. The influence factors relevant to SAE-DLLME including extraction parameters and instrumental conditions, were studied in detail. Under the optimal conditions, the limit of detection (LOD) for nickel was 0.24 ?g L-1, with sensitivity enhancement factor (EF) of 23.

  20. In situ sensor technology for simultaneous spectrophotometric measurements of seawater total dissolved inorganic carbon and pH.

    PubMed

    Wang, Zhaohui Aleck; Sonnichsen, Frederick N; Bradley, Albert M; Hoering, Katherine A; Lanagan, Thomas M; Chu, Sophie N; Hammar, Terence R; Camilli, Richard

    2015-04-01

    A new, in situ sensing system, Channelized Optical System (CHANOS), was recently developed to make high-resolution, simultaneous measurements of total dissolved inorganic carbon (DIC) and pH in seawater. Measurements made by this single, compact sensor can fully characterize the marine carbonate system. The system has a modular design to accommodate two independent, but similar measurement channels for DIC and pH. Both are based on spectrophotometric detection of hydrogen ion concentrations. The pH channel uses a flow-through, sample-indicator mixing design to achieve near instantaneous measurements. The DIC channel adapts a recently developed spectrophotometric method to achieve flow-through CO2 equilibration between an acidified sample and an indicator solution with a response time of only ? 90 s. During laboratory and in situ testing, CHANOS achieved a precision of ±0.0010 and ± 2.5 ?mol kg(-1) for pH and DIC, respectively. In situ comparison tests indicated that the accuracies of the pH and DIC channels over a three-week time-series deployment were ± 0.0024 and ± 4.1 ?mol kg(-1), respectively. This study demonstrates that CHANOS can make in situ, climatology-quality measurements by measuring two desirable CO2 parameters, and is capable of resolving the CO2 system in dynamic marine environments. PMID:25720851