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1

Rapid Analysis of Glibenclamide Using an Environmentally Benign Stability-Indicating RP-HPLC Method.  

PubMed

An environmentally benign RP-HPLC approach for rapid analysis of glibenclamide in pure form, developed nanoemulsion and commercial tablets was developed and validated in present investigation. The green chromatographic identification was performed on Lichrosphere 250 X 4.0 mm RP C8 column having a 5 ?m packing as a stationary phase using a combination of ethanol: methanol (50:50 % v/v) as a mobile phase, at a flow rate of 1.0 mL/min with UV detection at 245 nm. The proposed method was validated for linearity, selectivity, accuracy, precision, robustness, sensitivity and specificity as per international conference on harmonization (ICH) guidelines. The utility of proposed method was verified by assay of glibenclamide in developed nanoemulsion and commercial tablets. The proposed method was found to be satisfactory in terms of selectivity, precision, accuracy, robustness, sensitivity and specificity. The content of glibenclamide in developed nanoemulsion and commercial tablets was found to be 100.50 % and 99.15 % respectively. The proposed method successfully resoled glibenclamide peak in the presence of its all type of degradation products which indicated stability-indicating property of the proposed method. These results indicated that the green chromatographic method could be successfully employed for routine analysis of glibenclamide in pure drug and various commercial formulations. PMID:25276186

Haq, Nazrul; Alanazi, Fars Kaed; Alsarra, Ibrahim Abdullah; Shakeel, Faiyaz

2014-01-01

2

Rapid Analysis of Glibenclamide Using an Environmentally Benign Stability-Indicating RP-HPLC Method  

PubMed Central

An environmentally benign RP-HPLC approach for rapid analysis of glibenclamide in pure form, developed nanoemulsion and commercial tablets was developed and validated in present investigation. The green chromatographic identification was performed on Lichrosphere 250 X 4.0 mm RP C8 column having a 5 ?m packing as a stationary phase using a combination of ethanol: methanol (50:50 % v/v) as a mobile phase, at a flow rate of 1.0 mL/min with UV detection at 245 nm. The proposed method was validated for linearity, selectivity, accuracy, precision, robustness, sensitivity and specificity as per international conference on harmonization (ICH) guidelines. The utility of proposed method was verified by assay of glibenclamide in developed nanoemulsion and commercial tablets. The proposed method was found to be satisfactory in terms of selectivity, precision, accuracy, robustness, sensitivity and specificity. The content of glibenclamide in developed nanoemulsion and commercial tablets was found to be 100.50 % and 99.15 % respectively. The proposed method successfully resoled glibenclamide peak in the presence of its all type of degradation products which indicated stability-indicating property of the proposed method. These results indicated that the green chromatographic method could be successfully employed for routine analysis of glibenclamide in pure drug and various commercial formulations. PMID:25276186

Haq, Nazrul; Alanazi, Fars Kaed; Alsarra, Ibrahim Abdullah; Shakeel, Faiyaz

2014-01-01

3

Stability-Indicating RP-HPLC Method for the Simultaneous Estimation of Doxofylline and Terbutalinesulphate in Pharmaceutical Formulations.  

PubMed

An isocratic, stability-indicating, reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed for the quantitative determination of doxofylline and terbutaline sulphate, used for the treatment of respiratory problems. The chromatographic separation was achieved on a Zorbax-SB Phenyl 250 × 4.6mm × 5 ?m column with the mobile phase consisting of a mixture of 25 mM ammonium acetate (pH 5.0) : acetonitrile (85:15 %v/v) at a flow rate of 1.0 ml/min. The eluate was monitored at 274 nm using a PDA detector. Forced degradation studies were performed on the bulk sample of doxofylline and terbutaline sulphate using acid (0.1N HCl), base (0.1N NaOH), oxidation (10% hydrogen peroxide), photolytic, and thermal degradation conditions. Good resolution was observed between the degradants and analytes. Degradation products resulting from the stress studies did not interfere with the detection of doxofylline and terbutaline sulphate, thus the assay is stability-indicating. The method has the requisite accuracy, selectivity, sensitivity, and precision for the simultaneous estimation of doxofylline and terbutaline sulphate in bulk and pharmaceutical dosage forms. The limit of quantitation and limit of detection were found to be 1.16 ?g/ml and 0.38 ?g/ml for doxofylline, 2.08 ?g/ml and 0.62 ?g/ml for terbutaline sulphate, respectively. PMID:24482767

Samanthula, Gananadhamu; Yadiki, Krishnaveni; Saladi, Shantikumar; Gutala, Sreekanth; Surendranath, K V

2013-12-01

4

A validated stability-indicating RP-HPLC assay method for Amsacrine and its related substances.  

PubMed

A validated specific stability indicating reversed-phase high-performance liquid chromatography method was developed for the quantitative determination of Amsacrine as well as its related substances determination in bulk samples, in presence of degradation products, and its process related impurities. Forced degradation studies were performed on bulk samples of Amsacrine as per International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human use (ICH) prescribed stress conditions using acid, base, oxidative, thermal stress, and photolytic degradation to show the stability indicating power of the method. Significant degradation was observed during basic hydrolysis, slight degradation was observed in oxidative and thermal stress, and no degradation was observed in other stress conditions. The chromatographic method was optimized using the samples generated from forced degradation studies and the impurity spiked solution. Good resolution between the peaks corresponds to process-related impurities and degradation products from the analyte were achieved on Inertsil ODS column using the mobile phase consists a mixture of 1.0% triethyl amine in 20 mM potassium dihydrogen orthophosphate, with pH adjusted to 6.5, with ortho phosphoric acid in water and acetonitrile using a simple linear gradient. The detection was carried out at wavelength 248 nm. The mass balance in each case was in between 99.4% to 99.9%, indicating that the developed method was stability-indicating. Validation of the developed method was carried out as per ICH requirements. The developed method was found to be suitable to check the quality of bulk samples of Amsacrine at the time of batch release and also during its stability studies. PMID:21801478

Devi, M Lalitha; Chandrasekhar, K B; Surendranath, K V; Rao, B M; Narayana, M B V

2011-08-01

5

Stability-Indicating RP-HPLC Method for Determination of Tamsulosin HCL in Pharmaceutical Dosage Form  

PubMed Central

A selective, specific and sensitive stability-indicating high-performance liquid chromatographic method was developed and validated for the determination of Tamsulosin in in pharmaceutical dosage forms. Celecoxib was used as Internal Standard (IS). The chromatographic conditions comprised of a reversed-phase Lichrocart / Lichrosphere C18 column (250 × 4.0 mm packed with 5) with mobile phase consisting of a mixture of Acetonitrile: T.D.W. in the ratio (40: 60). Flow rate was 0.8 mL / min. Detection was carried out at 275 nm. The retention time of Tamsulosin HCl and Celecoxib were found to be 1.608 and 2.767min respectively and the linear regression analysis data for the calibration plots showed good linear relationship in the concentration range 1 - 200 g/mL. The value of correlation coefficient, slope and intercept were, 0.9995, 0.7453 and 0.4584, respectively. Tamsulosin HCl was subjected to stress conditions of degradation in aqueous solutions including acidic, alkaline, oxidation, photolysis and thermal degradation. The developed method was validated with regard to linearity, accuracy, precision, selectivity and robustness and the method was found to be precise, accurate, linear and specific. The method was employed successfully for identification and determination of Tamsulosin in pharmaceutical preparations. PMID:24826033

Kumar, G S; Kumar, B Sai Pavan

2012-01-01

6

Stability Indicating RP-HPLC Estimation of Atorvastatin Calcium and Amlodipine Besylate in Pharmaceutical Formulations  

PubMed Central

A simple, specific, accurate and stability indicating reversed phase high performance liquid chromatographic method was developed for the simultaneous determination of atorvastatin calcium and amlodipine besylate in tablet dosage forms. A phenomenex Gemini C-18, 5 ?m column having 250×4.6 mm i.d. in isocratic mode, with mobile phase containing 0.02 M potassium dihydrogen phosphate:acetonitrile:methanol (30:10:60, v/v/v) adjusted to pH 4 using ortho phosphoric acid was used. The flow rate was 1.0 ml/min and effluents were monitored at 240 nm. The retention times of atorvastatin calcium and amlodipine besylate were 11.6 min and 4.5 min, respectively. The calibration curves were linear in the concentration range of 0.08-20 ?g/ml for atorvastatin calcium and 0.1-20 ?g/ml for amlodipine besylate. Atorvastatin calcium and amlodipine besylate stock solutions were subjected to acid and alkali hydrolysis, chemical oxidation and dry heat degradation. The degraded product peaks were well resolved from the pure drug peak with significant difference in their retention time values. The proposed method was validated and successfully applied to the estimation of atorvastatin calcium and amlodipine besylate in combined tablet dosage forms. PMID:21369436

Shah, D. A.; Bhatt, K. K.; Mehta, R. S.; Baldania, S. L.; Gandhi, T. R.

2008-01-01

7

Stability Indicating RP-HPLC Estimation of Atorvastatin Calcium and Amlodipine Besylate in Pharmaceutical Formulations.  

PubMed

A simple, specific, accurate and stability indicating reversed phase high performance liquid chromatographic method was developed for the simultaneous determination of atorvastatin calcium and amlodipine besylate in tablet dosage forms. A phenomenex Gemini C-18, 5 ?m column having 250×4.6 mm i.d. in isocratic mode, with mobile phase containing 0.02 M potassium dihydrogen phosphate:acetonitrile:methanol (30:10:60, v/v/v) adjusted to pH 4 using ortho phosphoric acid was used. The flow rate was 1.0 ml/min and effluents were monitored at 240 nm. The retention times of atorvastatin calcium and amlodipine besylate were 11.6 min and 4.5 min, respectively. The calibration curves were linear in the concentration range of 0.08-20 ?g/ml for atorvastatin calcium and 0.1-20 ?g/ml for amlodipine besylate. Atorvastatin calcium and amlodipine besylate stock solutions were subjected to acid and alkali hydrolysis, chemical oxidation and dry heat degradation. The degraded product peaks were well resolved from the pure drug peak with significant difference in their retention time values. The proposed method was validated and successfully applied to the estimation of atorvastatin calcium and amlodipine besylate in combined tablet dosage forms. PMID:21369436

Shah, D A; Bhatt, K K; Mehta, R S; Baldania, S L; Gandhi, T R

2008-11-01

8

Validated stability indicating RP-HPLC method for simultaneous determination and in vitro dissolution studies of thiocolchicoside and diclofenac potassium from tablet dosage form  

Microsoft Academic Search

A simple, rapid, and robust stability indicating RP-HPLC method has been developed and validated to measure thiocolchicoside (TH) and diclofenac potassium (DP) at single wavelength (258nm) in order to assess assay and in vitro drug release profile of drug from tablet formulation. A gradient elution of samples performed on Zorbax SB CN 250mm×4.6mm, 5?m column with buffered mobile phase consisting

Suraj D. Jadhav; S. R. Butle; Sachin D. Patil; P. K. Jagtap

9

Development and Validation of a Novel Stability-Indicating RP-HPLC Method for the Simultaneous Determination of Halometasone, Fusidic Acid, Methylparaben, and Propylparaben in Topical Pharmaceutical Formulation.  

PubMed

A stability-indicating reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed for the simultaneous determination of halometasone, fusidic acid, methylparaben, and propylparaben in topical pharmaceutical formulation. The desired chromatographic separation was achieved on an Agilent Zorbax CN (Cyano), 5 ?m (250 × 4.6 mm) column using gradient elution at 240 nm detector wavelength. The optimized mobile phase consisted of a mixture of 0.01 M phosphate buffer and 0.1% orthophosphoric acid, pH-adjusted to 2.5 with an ammonia solution as solvent-A and acetonitrile as solvent-B. The developed method separated halometasone, fusidic acid, methylparaben, and propylparaben in the presence of known impurities/degradation products. The stability-indicating capability was established by forced degradation experiments and separation of known and unknown degradation products. The developed RP-HPLC method was validated according to the International Conference on Harmonization (ICH) guidelines. This validated method was applied for the simultaneous estimation of HM, FA, MP, and PP in commercially available cream samples. Further, the method can be extended for the estimation of HM, FA, MP, and PP in various commercially available dosage forms. PMID:23833716

Goswami, Nishant; Gupta, V Rama Mohan; Jogia, Hitesh A

2013-06-01

10

A Rapid, Stability-Indicating RP-HPLC Method for the Simultaneous Determination of Formoterol Fumarate, Tiotropium Bromide, and Ciclesonide in a Pulmonary Drug Product  

PubMed Central

A stability-indicating reversed-phase high performance liquid chromatography (RP-HPLC) method was developed for the simultaneous determination of Formoterol fumarate (FOR), Tiotropium bromide (TRI), and Ciclesonide (CLS) in a pulmonary drug product. The desired chromatographic separation was achieved on the Zorbax SB C8, 5 ?m (150 × 4.6 mm) column, using gradient elution at 230 nm detector wavelength. The optimized mobile phase consisted of a 0.2 % v/v perchloric acid as solvent-A and acetonitrile as solvent-B. The developed method separated FOR, TRI, and CLS in the presence of its five unknown degradation products within 10 minutes. The stability-indicating capability was established by forced degradation experiments and the separation of unknown degradation products. The developed RP-HPLC method was validated according to the International Conference on Harmonization (ICH) guidelines. This validated method was applied for the simultaneous estimation of FOR, TRI, and CLS in commercially available Triohale® pMDI (Pressurized Metered-Dose Inhaler) samples. Furthermore, this method can be extended for individual estimation of FOR, TRI, and CLS in various commercially available pulmonary dosage forms. PMID:23008808

Trivedi, Rakshit Kanubhai; Chendake, Dhairyshil S.; Patel, Mukesh C.

2012-01-01

11

A Rapid, Stability-Indicating RP-HPLC Method for the Simultaneous Determination of Formoterol Fumarate, Tiotropium Bromide, and Ciclesonide in a Pulmonary Drug Product.  

PubMed

A stability-indicating reversed-phase high performance liquid chromatography (RP-HPLC) method was developed for the simultaneous determination of Formoterol fumarate (FOR), Tiotropium bromide (TRI), and Ciclesonide (CLS) in a pulmonary drug product. The desired chromatographic separation was achieved on the Zorbax SB C8, 5 ?m (150 × 4.6 mm) column, using gradient elution at 230 nm detector wavelength. The optimized mobile phase consisted of a 0.2 % v/v perchloric acid as solvent-A and acetonitrile as solvent-B. The developed method separated FOR, TRI, and CLS in the presence of its five unknown degradation products within 10 minutes. The stability-indicating capability was established by forced degradation experiments and the separation of unknown degradation products. The developed RP-HPLC method was validated according to the International Conference on Harmonization (ICH) guidelines. This validated method was applied for the simultaneous estimation of FOR, TRI, and CLS in commercially available Triohale(®) pMDI (Pressurized Metered-Dose Inhaler) samples. Furthermore, this method can be extended for individual estimation of FOR, TRI, and CLS in various commercially available pulmonary dosage forms. PMID:23008808

Trivedi, Rakshit Kanubhai; Chendake, Dhairyshil S; Patel, Mukesh C

2012-09-01

12

Development of a Stability-Indicating RP-HPLC Method for the Determination of Rupatadine and its Degradation Products in Solid Oral Dosage Form.  

PubMed

A simple, sensitive, and reproducible reversed-phase high-performance liquid chromatography (RP-HPLC) method, coupled with a photodiode array detector, was developed for the determination of rupatadine (RUPA) and its related substances in pharmaceutical dosage forms. Chromatographic separation was achieved on the Hypersil BDS (150 x 4.6 mm, 5 ?m) column with a mobile phase containing a gradient mixture of a buffer (acetate buffer pH-6.0) and solvent (methanol). The eluted compounds were monitored at 264 nm for the related substances and assay, the flow rate was 1.0 mL/min, and the column oven temperature was maintained at 50°C. The developed method separated RUPA from its four known and three unknown impurities within 15.0 min. Rupatadine was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal, and photolytic degradation. Rupatadine was found to degrade significantly under oxidative stress conditions, and degrade slightly under acid, base, hydrolytic, thermal, and photolytic stress conditions. All impurities were well-resolved from each other and from the main peak, showing the stability-indicating power of the method. The developed method was validated as per the International Conference on Harmonization (ICH) guidelines. The developed and validated RP-HPLC method is LC-MS compatible and can be explored for the identification of eluted unknown impurities of RUPA. PMID:23264938

Trivedi, Harshal Kanubhai; Patel, Mukesh C

2012-12-01

13

FORCED DEGRADATION AND PH STABILITY STUDIES OF LYSERGOL: AN ERGOLIC ALKALOID BY STABILITY INDICATING RP HPLC-UV METHOD  

Microsoft Academic Search

A simple HPLC-UV method was developed and validated for the analysis of lysergol, its stress degradation profile, and pH stability studies. Instrument used was Agilent HPLC 1120 autosampler with a C18 reversed phase column and a mobile phase comprised of methanol and water (1% acetic acid) with isocratic flow. Flow rate was kept constant at 1 mL\\/min throughout the experiment and

Shamama Javed; Kanchan Kohli; Mushir Ali

2012-01-01

14

Stability-indicating RP-HPLC Method for the Simultaneous Determination of Sitagliptin and Simvastatin in Tablets  

PubMed Central

A new stability-indicating high-performance liquid chromatographic method for simultaneous analysis of sitagliptin and simvastatin in pharmaceutical dosage form was developed and validated. The mobile phase consisted of methanol and water (70:30, v/v) with 0.2 % of n-heptane sulfonic acid adjusted to pH 3.0 with ortho phosphoric acid was used. Retentions of sitagliptin and simvastatin were 4.3 min and 30.4 min, respectively with a flow rate of 1 ml/min on C8 (Qualisil BDS, 250×4.6 mm, 5 ?). Eluents were detected at 253 nm using photodiode diode array detector. The linear regression analysis data for the linearity plot showed correlation coefficient values of 0.9998 and 0.9993 for sitagliptin and simvastatin, with respective concentration ranges of 20-150 ?g/ml and 8-60 ?g/ml. The relative standard deviation for inter-day precision was lower than 2.0%. The assay of sitagliptin and simvastatin was determined in tablet dosage form was found to be within limits. Both drugs were subjected to a variety of stress conditions such as acidic, basic, oxidation, photolytic, neutral and thermal stress in order to achieve adequate degradation. Results revealed that considerable degradation was found in all stress conditions except oxidative degradations. The method has proven specificity for stability indicating assay method.

Ramalingam, P.; Bhaskar, V. Udaya; Reddy, Y. Padmanabha; Kumar, K. Vinod

2014-01-01

15

VALIDATED STABILITY INDICATING RP-HPLC METHOD FOR THE ESTIMATION OF LINEZOLID IN A PHARMACEUTICAL DOSAGE FORM  

Microsoft Academic Search

A rapid high performance liquid chromatographic method was developed and validated for the determination and stability evaluation of linezolid in pharmaceutical dosage forms. Separation of linezolid was successfully achieved on a C-18 column utilizing water: methanol (50:50 v\\/v) at a flow rate of 1 mL\\/min and eluate was monitored at 254 nm, with a retention time of 5.117 minute. The method was validated

Sharmistha Mohapatra; M. Mathrusri Annapurna; B. V. V. Ravi Kumar; Mohammed Anwar; Musarrat Husain Warsi; Sohail Akhter

2011-01-01

16

Development and Validation of a Stability-Indicating RP-HPLC Method for the Estimation of Drotaverine Impurities in API and Pharmaceutical Formulation.  

PubMed

A sensitive, stability-indicating gradient RP-HPLC method with PDA detection has been developed for the simultaneous analysis of drotaverine impurities in active pharmaceutical ingredient (API) and pharmaceutical formulations. Efficient chromatographic separation was achieved on an XTerra RP18, 150 × 4.6 mm, 5 ?m column using gradient elution at 230 nm detection wavelength. The optimized mobile phase consisted of a 0.02 M potassium dihydrogen orthophosphate buffer of pH 3.0 as solvent A and acetonitrile as solvent B. The flow rate of the mobile phase was 1.0 mL min(-1) with a column temperature of 25°C. The method showed linearity over the range of 0.251-10.033 ?g/mL, 0.231-9.995 ?g/mL, 0.230-10.089 ?g/mL, 0.334-10.011 ?g/mL, and 0.324-10.050 ?g/mL for impurities 1, 2, 3, 4, and drotaverine, respectively, with a correlation coefficient greater than 0.999. The relative retention times and relative response factors of impurities 1, 2, 3, 4 were 0.36, 0.90, 1.42, 1.55 and 1.04, 0.84, 1.10, 1.30, respectively. The drotaverine formulation sample was subjected to the stress conditions of acid, base, oxidative, thermal, humidity, and photolytic degradation. Drotaverine was found to degrade significantly in peroxide, base, and heat stress conditions. The degradation products were well-resolved from drotaverine and its impurities. The peak purity test results confirmed that the drotaverine peak was homogenous and pure in all stress samples and the mass balance was found to be more than 98%, thus proving the stability-indicating power of the method. The developed method was validated according to ICH guidelines with respect to specificity, linearity, limit of detection and quantification, accuracy, precision, and robustness. PMID:24634845

Thummala, Veera Raghava Raju; Tharlapu, Satya Sankarsana Jagan Mohan; Rekulapalli, Vijay Kumar; Ivaturi, Mrutyunjaya Rao; Nittala, Someswara Rao

2014-03-01

17

Method Development and Validation of a Stability-Indicating RP-HPLC Method for the Quantitative Analysis of Dronedarone Hydrochloride in Pharmaceutical Tablets.  

PubMed

A simple, precise, and accurate HPLC method has been developed and validated for the quantitative analysis of Dronedarone Hydrochloride in tablet form. An isocratic separation was achieved using a Waters Symmetry C8 (100 × 4.6 mm), 5 ?m particle size column with a flow rate of 1 ml/min and UV detector at 290 nm. The mobile phase consisted of buffer: methanol (40:60 v/v) (buffer: 50 mM KH2PO4 + 1 ml triethylamine in 1 liter water, pH=2.5 adjusted with ortho-phosphoric acid). The method was validated for specificity, linearity, precision, accuracy, robustness, and solution stability. The specificity of the method was determined by assessing interference from the placebo and by stress testing the drug (forced degradation). The method was linear over the concentration range 20-80 ?g/ml (r(2) = 0.999) with a Limit of Detection (LOD) and Limit of Quantitation (LOQ) of 0.1 and 0.3 ?g/ml respectively. The accuracy of the method was between 99.2-100.5%. The method was found to be robust and suitable for the quantitative analysis of Dronedarone Hydrochloride in a tablet formulation. Degradation products resulting from the stress studies did not interfere with the detection of Dronedarone Hydrochloride so the assay is thus stability-indicating. PMID:23641332

Dabhi, Batuk; Jadeja, Yashwantsinh; Patel, Madhavi; Jebaliya, Hetal; Karia, Denish; Shah, Anamik

2013-03-01

18

Method Development and Validation of a Stability-Indicating RP-HPLC Method for the Quantitative Analysis of Dronedarone Hydrochloride in Pharmaceutical Tablets  

PubMed Central

A simple, precise, and accurate HPLC method has been developed and validated for the quantitative analysis of Dronedarone Hydrochloride in tablet form. An isocratic separation was achieved using a Waters Symmetry C8 (100 × 4.6 mm), 5 ?m particle size column with a flow rate of 1 ml/min and UV detector at 290 nm. The mobile phase consisted of buffer: methanol (40:60 v/v) (buffer: 50 mM KH2PO4 + 1 ml triethylamine in 1 liter water, pH=2.5 adjusted with ortho-phosphoric acid). The method was validated for specificity, linearity, precision, accuracy, robustness, and solution stability. The specificity of the method was determined by assessing interference from the placebo and by stress testing the drug (forced degradation). The method was linear over the concentration range 20–80 ?g/ml (r2 = 0.999) with a Limit of Detection (LOD) and Limit of Quantitation (LOQ) of 0.1 and 0.3 ?g/ml respectively. The accuracy of the method was between 99.2–100.5%. The method was found to be robust and suitable for the quantitative analysis of Dronedarone Hydrochloride in a tablet formulation. Degradation products resulting from the stress studies did not interfere with the detection of Dronedarone Hydrochloride so the assay is thus stability-indicating. PMID:23641332

Dabhi, Batuk; Jadeja, Yashwantsinh; Patel, Madhavi; Jebaliya, Hetal; Karia, Denish; Shah, Anamik

2013-01-01

19

Development and validation of a stability indicating assay of doxofylline by RP-HPLC: ESI-MS/MS, ¹H and ¹³C NMR spectroscopic characterization of degradation products and process related impurities.  

PubMed

A validated stability indicating RP-HPLC assay of doxofylline was developed by separating its related substances and degradants on LichrocartC18 (250 mm × 4.6 mm; 5 ?m) column using 10 mM ammonium acetate and acetonitrile as a mobile phase in a gradient mode of elution at a flow rate of 1.0 mL/min at 30 °C. The column effluents were monitored by a photo diode array detector set at 274 nm. The method was validated in terms of accuracy, precision and linearity as per ICH guidelines. The limits of quantification of doxofylline and impurities were obtained in the range of 0.19-0.36 ?g/mL. Forced degradation of doxofylline was carried out under acidic, basic, thermal, photo, peroxide conditions and the degradation products were isolated and characterized by ESI-MS/MS, (1)H and (13)C spectroscopy. The method was successfully applied not only to quantify related substances and degradation products but also assay of doxofylline in bulk drugs. The recoveries of doxofylline and impurities were in the range of 99.00-100.05% and 97.83-99.86% respectively. PMID:23466440

Rao, R Nageswara; Naidu, Ch Gangu; Prasad, K Guru; Santhakumar, B; Saida, Shaik

2013-05-01

20

Development and validation of stability indicating the RP-HPLC method for the estimation of related compounds of guaifenesin in pharmaceutical dosage forms  

PubMed Central

Aim and background: A stability-indicating gradient reverse phase liquid chromatographic (RP-LC) method was developed for the quantitative determination of related substances of guaifenesin in pharmaceutical formulations. Materials and methods: The baseline separation for guaifenesin and all impurities was achieved by utilizing a Water Symmetry C18 (150 mm × 4.6 mm) 5 ?m column particle size and a gradient elution method. The mobile phase A contains a mixture of 0.02 M KH2PO4 (pH 3.2) and methanol in the ratio of 90:10 v/v, while the mobile phase B contains 0.02 M KH2PO4 (pH 3.2) and methanol in the ratio of 10:90 v/v, respectively. The flow rate of the mobile phase was 0.8 ml/min with a column temperature of 25°C and detection wavelength at 273 nm. Results: Guaifenesin was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal, and photolytic degradation. Conclusion: The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of detection and quantification, accuracy, precision, and robustness. PMID:23781462

Reddy, Sunil Pingili; Babu, K. Sudhakar; Kumar, Navneet; Sekhar, Y. V. V. Sasi

2011-01-01

21

Validated Stability Indicating RP-HPLC for Quantitation of Nitazoxanide in Presence of Its Alkaline Degradation Products and Their Characterization by HPLC-Tandem Mass Spectrometry.  

PubMed

A simple and sensitive stability indicating HPLC method was developed and validated for quantitative determination of Nitazoxanide (NTZ), a new antiprotozoal drug, in presence of degradation products generated under forced alkaline hydrolysis. Chromatographic separation was achieved on Inertsil C8-3 column (150 × 4.6 mm i.d.) using a mobile phase composed of acetonitrile: 50 mM ammonium acetate buffer (50:50, v/v, pH 5.0 adjusted with acetic acid) at a flow rate of 1 mL/min. Quantification was achieved with UV detection at 298 nm based on relative peak area. The method was linear over the concentration range of 0.8-50 µg/mL (r = 0.9999) with a limit of detection and quantification 0.0410 and 0.1242 µg/mL, respectively. The developed method has the requisite accuracy, selectivity, sensitivity and precision to assay NTZ in presence of its degradation products either in bulk powder or in pharmaceutical formulations. The degradation products were then identified by HPLC-MS/MS analysis using an electrospray ionization source and an ion trap analyzer. PMID:24248557

Hegazy, Maha; Kessiba, Amira; El Gindy, Ahmed Emad; Abdelkawy, Mohamed

2014-10-01

22

Development and validation of a stability-indicating RP-HPLC method for the simultaneous estimation of process related impurities and degradation products of rasagiline mesylate in pharmaceutical formulation.  

PubMed

A sensitive, stability-indicating gradient reverse phase high-performance liquid chromatography-ultraviolet method has been developed for the quantitative determination of process-related impurities and forced degradation products of rasagiline mesylate in pharmaceutical formulation. Efficient chromatographic separation was achieved on an ACE C8, 150 × 4.6 mm, 3 µm column with mobile phase containing a gradient mixture of solvents A and B. The flow rate of the mobile phase was 0.8 mL/min with column temperature of 30°C and detection wavelength at 210 nm. Rasagiline was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. Rasagiline was found to degrade significantly in acid and thermal stress conditions. The degradation products were well resolved from rasagiline and its impurities. The peak purity test results confirmed that the rasagiline peak was homogenous and pure in all stress samples and the mass balance was found to be more than 97%, thus proving the stability-indicating power of the method. The developed method was validated according to the guidelines of the International Conference on Harmonization with respect to specificity, linearity, limits of detection and quantification, accuracy, precision and robustness. PMID:22988002

Reddy, P Sunil; Sudhakar Babu, K; Kumar, Navneet

2013-03-01

23

Development and Validation of a Stability-Indicating RP-HPLC Method for the Determination of Process-Related Impurities and Degradation Products of Rabeprazole Sodium in Pharmaceutical Formulation.  

PubMed

The objective of the current study was to develop and validate a reversed-phase high-performance liquid chromatographic method for the quantitative determination of process-related impurities and degradation products of rabeprazole sodium in pharmaceutical formulation. Chromatographic separation was achieved on the Waters Symmetry Shield RP18 (250 mm × 4.6 mm) 5 ?m column with a mobile phase containing a gradient mixture of solvent A (mixture of 0.025 M KH2PO4 buffer and 0.1% triethylamine in water, pH 6.4 and acetonitrile in the ratio of 90:10 v/v, respectively) and solvent B (mixture of acetonitrile and water in the ratio of 90:10 v/v, respectively). The mobile phase was delivered at a flow rate of 1.0 mL/min and with UV detection at 280 nm. Rabeprazole sodium was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal, and photolytic degradation. Rabeprazole sodium was found to degrade significantly under acid hydrolysis, base hydrolysis, oxidative, and thermal degradation conditions. The degradation products were well-resolved from the main peak and its impurities, thus proving the stability-indicating power of the method. The mass balance was found to be in the range of 97.3-101.3% in all of the stressed conditions, thus proving the stability-indicating power of the method. The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision, and robustness. PMID:24106668

Kumar, Navneet; Sangeetha, Dhanaraj

2013-01-01

24

Comparability of RP-HPLC Retention Indices of Drugs in Three Databases  

Microsoft Academic Search

Three databases of HPLC retention indices in the 1-nitroalkane scale were recently established (IFM = Institute of Forensic Medicine, MCL = Microchemistry Laboratory, MTSS = Merck Tox Screening System). In two of them (IFM and MTSS) virtually identical chromatographic conditions were applied but different RP-columns. In the third system (MCL) a different column and different elution conditions were used. Among

Maciej Bogusz; Dennis W. Hill; Astrid Rehorek

1996-01-01

25

Identification of Rhodiola species by using RP-HPLC*  

PubMed Central

An approach was established using RP-HPLC (reversed-phase high-performance liquid chromatography) to identify ten species of Rhodiola, R. coccinea A. Bor, R. junggarica C.Y. Yang et N.R. Cui spn., R. heterodonta A. Bor, R. linearifolia A. Bor, R. pamiro alaiucm A. Bor, R. kaschgarica A. Bor, R. litwinowii A. Bor, R. gelida schrenk, R. rosea L. and R. quadrifide Fisch et Mey collected from the Tianshan Mountains areas of China. Chromatograms of alcohol-soluble proteins, generated from these ten Rhodiola spp. were compared. Each chromatogram of alcohol-soluble proteins came from a single seed of one wild species only. The results showed that when using a Waters Delta Pak. C18, 5 ?m particle size reversed phase column (150 mm×3.9 mm), a linear gradient of 22%–55% solvent B with a flow rate of 1 ml/min and a run time of 67 min, the chromatography gave optimum separation of Rhodiola alcohol-soluble proteins. Chromatogram of each species was different and could be used to identify those species. Cluster analysis of genetic similarity coefficients of 37% to 60% showed a medium degree of genetic diversity among the species in these eco-areas. Cluster analysis showed that the ten species of Rhodiola can be divided into four clusters and yielded the general and unique biochemical markers of these species. RP-HPLC was shown to be a rapid, repeatable and reliable method for Rhodiola species identification and analysis of genetic diversity. PMID:15909330

Wang, Qiang; Ruan, Xiao; Jin, Zhi-hua; Yan, Qi-chuan; Tu, Shan-jun

2005-01-01

26

In vitro interaction studies of diltiazem with NSAID's using UV spectrophotometry and RP-HPLC techniques.  

PubMed

Diltiazem (DTZ) is a well-known cardiovascular drug used clinically in the treatment of angina pectoris and hypertension. Present paper deals with the in vitro availability studies of DTZ in presence of commonly used nonsteroidal anti-inflammatory drugs (NSAID's) like diclofenac sodium, flurbiprofen, mefenamic acid and meloxicam. Simultaneous administration of both types of drugs may alter the antihypertensive effect of DTZ. These studies were carried out using BP 2005 dissolution test apparatus in simulated human body environments at body temperature and at elevated temperature in order to study the kinetics and energitics of these interactions. Both the drug in each case were analyzed either by measuring the absorbance of aliquots on a UV/VIS spectrophotometer, or by RP-HPLC method. Present study clearly indicated that most of the NSAID's studied bind to DTZ forming charge transfer complexes, evident from the high availability of DTZ. Hence, concurrent administration of NSAID's with DTZ is not recommended. PMID:17545105

Sultana, Najma; Arayne, M Saeed; Shafi, Nighat

2007-07-01

27

An RP-HPLC determination of 5-hydroxymethylfurfural in honey The case of strawberry tree honey.  

PubMed

The use of the RP-HPLC official method of the International Honey Commission (IHC) for the determination of 5-hydroxymethylfurfural (HMF) in strawberry tree honey (Arbutus unedo, a typical Sardinian honey) has brought to light a specific and heavy chromatographic interference that prevents accurate quantification. The interference has been identified as homogentisic acid (HA), i.e. the marker of the botanical origin of the honey. For this reason, an alternative RP-HPLC method is proposed. The bias-free method allows a complete separation of HMF from HA to the baseline level and is faster and more precise than the RP-HPLC official method: the detection and quantification limits are 1.9 and 4.0mgkg(-1), respectively, whereas the repeatability is ca. 2% in the HMF concentration range of 5-140mgkg(-1). PMID:18970477

Spano, Nadia; Casula, Lucia; Panzanelli, Angelo; Pilo, Maria I; Piu, Paola C; Scanu, Roberta; Tapparo, Andrea; Sanna, Gavino

2006-02-15

28

Analysis by RP-HPLC of mangiferin component correlation between medicinal loranthus and their mango host trees.  

PubMed

This study proposes a reversed-phase high-performance liquid chromatography (RP-HPLC) method for the determination of mangiferin in medicinal loranthus shrubs and their mango or non-mango host trees. Mangiferin in samples was extracted with a solution of 40% methanol. Analytical determination was conducted by RP-HPLC with ultraviolet detection at 258 nm. Chromatographic separation was achieved on an Inertsil ODS-SP column (250 × 4.6 mm, 5 µm) by isocratic elution with methanol-0.1% aqueous phosphoric acid (31:69, v/v). Mangiferin contents were 5.04 to 18.95 mg/g in mango trees and 0.44 to 3.72 mg/g in medicinal loranthus parasitized on mango host trees. Mangiferin could not be detected in non-mango trees and their loranthus shrubs. This study indicated that host trees could affect the quality of medicinal loranthus by transporting host-inherent components into loranthus. PMID:23247031

Zhang, Xiejun; Su, Benwei; Li, Jing; Li, Yonghua; Lu, Dong; Zhu, Kaixin; Pei, Hehuan; Zhao, Minghui

2014-01-01

29

Optical resolution of phosphorus containing calix[4]arenes by additive RP HPLC method.  

PubMed

The RP HPLC method (LiChrosorb RP18 or Separon SGX C18 column, acetonitrile-water 86:14 v/v mobile phase) was applied for enantiomeric separation of topologically chiral 5-bromo-25,26-bis(diethoxyphosphoryl)calix[4]arene 9 or 25-ethyl-26-dihydroxyphosphoryl-calix[4]arene 5. Separation of calixarene 9 was achieved by the addition of D-(-)-tartaric acid which formed hydrogen bonded diastereomeric associates with 9 to the mobile phase. Calixarenephosphoric acid 5 was transformed into diastereomeric salt 6 by addition of L-(-)-alpha-phenylethylamine before RP HPLC separation. PMID:11126879

Kalchenko, O I; Tairov, M O; Vysotsky, M O; Lipkowski, J; Kalchenko, V I

2000-01-01

30

Preparation of (+)-Trans-Isoalliin and Its Isomers by Chemical Synthesis and RP-HPLC Resolution  

PubMed Central

Naturally occurring (+)-trans-isoalliin, (RCRS)-(+)-trans-S-1-propenyl-L-cysteine sulfoxide, is a major cysteine sulfoxide in onion. The importance of producing it synthetically to support further research is very well recognized. The (+)-trans-isoalliin is prepared by chemical synthesis and reversed-phase (RP)-HPLC. First, S-2-propenyl-L-cysteine (deoxyalliin) is formed from L-cysteine and allyl bromide, which is then isomerized to S-1-propenyl-L-cysteine (deoxyisoalliin) by a base-catalyzed reaction. A mixture of cis and trans forms of deoxyisoalliin is formed and separated by RP-HPLC. Oxidation of the trans form of deoxyisoalliin by H2O2 produces a mixture of (?)- and (+)-trans-isoalliin. Finally, RP-HPLC is used successfully in separating (?)- and (+)-trans-isoalliin, and hence, (+)-trans-isoalliin is synthesized for the first time in this study. In addition, the (±) diastereomers of cis-isoalliin are also separated and purified by RP-HPLC. PMID:25187757

Jayathilaka, Lasanthi; Gupta, Shalini; Huang, Jin-Sheng; Lee, Jenny; Lee, Bao-Shiang

2014-01-01

31

New determination method for sulfonation degree of phthalic anhydride by RP-HPLC.  

PubMed

A novel method was developed to monitor the reaction process and evaluate the sulfonation level in the sulfonation of phthalic anhydride by reversed-phase high-performance liquid chromatography (RP-HPLC). The product peak was identified in chromatograms through product analysis and by comparing its retention time with that of standard compounds. By comparing the hydrolysis and alcoholysis methods, optimized pretreatment of the sample was found for RP-HPLC. Based on the determined percentages of phthalic anhydride and sulfonated phthalic anhydride in the mixture, the degree of sulfonation was calculated. When the sulfonation degree of phthalic anhydride was in the range of 2.8-71%, the recovery of 97-104% was achieved, and the procedure was rapid and accurate. PMID:23680900

Zhu, Lijun; Song, Lechun; Liu, Bin; Zhou, Yulu; Xiang, Yuzhi; Xia, Daohong

2014-01-01

32

RP-HPLC determination of water-soluble vitamins in honey  

Microsoft Academic Search

The assessment and validation of reliable analytical methods for the determination of vitamins in sugar-based matrices (e.g. honey) are still scarcely explored fields of research. This study proposes and fully validates a simple and fast RP-HPLC method for the simultaneous determination of five water-soluble vitamins (vitamin B2, riboflavin; vitamin B3, nicotinic acid; vitamin B5, pantothenic acid; vitamin B9, folic acid;

Marco Ciulu; Silvia Solinas; Ignazio Floris; Angelo Panzanelli; Maria I. Pilo; Paola C. Piu; Nadia Spano; Gavino Sanna

2011-01-01

33

Quantitative analysis of quercetin in Euphorbia helioscopia L by RP-HPLC.  

PubMed

Euphorbia helioscopia L is widespread in China and has a large number of flavonoids. Quercetin glycosides, having useful biological activities, are abundant in this plant, and no validated analytical method has so far been developed for their determination. We, therefore, standardized a reversed-phase high-performance liquid chromatography (RP-HPLC) assay for quercetin detection. For this, the plant was locally procured and identification was confirmed based on its morpho-histological characteristics. Ethyl acetate extracts of leaves, stems, and roots were analyzed by RP-HPLC using Agilent 1120 HPLC TC-C(18) column (250 × 4.6 mm; 5 ?m) with UV-detector system. The mobile phase of methanol-0.2% phosphoric acid (65:35) solution was used with the flow rate of 1.0 ml min(-1) at 30°C, and the detection was performed at 360 nm wavelength. Our data show that the linear range of quercetin was 0.025-0.150 mg.ml(-1) (r = 0.9995; n = 6) with the recovery rate of 97.50-103.30% (average 100.40%; RSD = 2.28%). The target component was baseline separated during only the period of 9 min. The repeatability of RP-HPLC analysis was demonstrated with an RSD of 1.77% (n = 6), and the highest quercetin content (average 1.42 mg g(-1)dry-weight) was present in leaves. It was, therefore, concluded that RP-HPLC is a simple, rapid, accurate, and sensitive method for the detection of quercetin from Euphorbia helioscopia L. PMID:21327945

Liu, Hai Peng; Shi, Xiao Feng; Zhang, You Cheng; Li, Zhong Xin; Zhang, Lin; Wang, Zhe Yuan

2011-09-01

34

Quantitative Analysis of Quercetin in Euphorbia helioscopia L by RP-HPLC  

Microsoft Academic Search

Euphorbia helioscopia L is widespread in China and has a large number of flavonoids. Quercetin glycosides, having useful biological activities,\\u000a are abundant in this plant, and no validated analytical method has so far been developed for their determination. We, therefore,\\u000a standardized a reversed-phase high-performance liquid chromatography (RP-HPLC) assay for quercetin detection. For this, the\\u000a plant was locally procured and identification

Hai Peng Liu; Xiao Feng Shi; You Cheng Zhang; Zhong Xin Li; Lin Zhang; Zhe Yuan Wang

35

SIMULTANEOUS DETERMINATION OF OFLOXACIN AND FLAVOXATE HYDROCHLORIDE IN HUMAN PLASMA BY RP HPLC  

Microsoft Academic Search

A sensitive RP HPLC method has been developed and validated for the determination of ofloxacin and flavoxate hydrochloride in spiked human plasma. For the estimation of drugs in plasma, sample pretreatment involved only protein precipitation by acetonitrile. Chromatographic separation was performed on a Kromasil C8 (4.6 mm × 250 mm, 5 µm) column, with mobile phase consisting of formic acid in water, methanol, and acetonitrile

Mahesh V. Attimarad; Sree Harsha N; Ramachandra S. Setty

2012-01-01

36

A Study of Method Development, Validation, and Forced Degradation for Simultaneous Quantification of Paracetamol and Ibuprofen in Pharmaceutical Dosage Form by RP-HPLC Method  

PubMed Central

A rapid and stability-indicating reversed phase high-performance liquid chromatography (RP-HPLC) method was developed for simultaneous quantification of paracetamol and ibuprofen in their combined dosage form especially to get some more advantages over other methods already developed for this combination. The method was validated according to United States Pharmacopeia (USP) guideline with respect to accuracy, precision, specificity, linearity, solution stability, robustness, sensitivity, and system suitability. Forced degradation study was validated according to International Conference on Harmonisation (ICH). For this, an isocratic condition of mobile phase comprising phosphate buffer (pH 6.8) and acetonitrile in a ratio of 65:35, v/v at a flow rate of 0.7 mL/minute over RP C18 (octadecylsilane (ODS), 150 × 4.6 mm, 5 ?m, Phenomenex Inc.) column at ambient temperature was maintained. The method showed excellent linear response with correlation coefficient (R2) values of 0.999 and 1.0 for paracetamol and ibuprofen respectively, which were within the limit of correlation coefficient (R2 > 0.995). The percent recoveries for two drugs were found within the acceptance limit of (97.0–103.0%). Intra-and inter-day precision studies of the new method were less than the maximum allowable limit percentage of relative standard deviation (%RSD) ? 2.0. Forced degradation of the drug product was carried out as per the ICH guidelines with a view to establishing the stability-indicating property of this method and providing useful information about the degradation pathways, degradation products, and how the quality of a drug substance and drug product changes with time under the influence of various stressing conditions. The degradation of ibuprofen was within the limit (5–20%, according to the guideline of ICH), while paracetamol showed <20% degradation in oxidation and basic condition.

Jahan, Md. Sarowar; Islam, Md. Jahirul; Begum, Rehana; Kayesh, Ruhul; Rahman, Asma

2014-01-01

37

Investigation on the origin of 5-HMF in Shengmaiyin decoction by RP-HPLC method  

Microsoft Academic Search

The origin of 5-HMF (5-hydroxymethyl-2-furaldehyde) in a Shengmaiyin decoction was investigated by the RP-HPLC method below.\\u000a AC18 column (250 mm×4.6 mm, i.d. 5 ?m) with a column temperature of 25°C was used. The mobile phase was a mixture of ultra-pure\\u000a water-acetonitrile (95?3,V\\/V) and the flow rate was 1.0 ml\\/min. The detection wavelength was 280 nm. The injection volume was 1

Li Ying-hua; Lu Xiu-yang

2005-01-01

38

Analytics of the therapeutic peptide aviptadil by sheathless CE-MS and comparison with nanoRP-HPLC-MS.  

PubMed

Purification and quality control of therapeutic peptides is often performed by one single method, RP-HPLC. As usage of an orthogonal technique is highly advisable for quality assurance, capillary electrophoresis (CE) employing a coated capillary coupled via a sheathless interface to a mass spectrometer was applied in parallel. The basic therapeutic peptide aviptadil served as a model substance to study the impurity profiles revealing 15 detectable impurities using CE-MS, two were detected by an appropriate nanoRP-HPLC-MS method. None of the impurities detected by CE were observed in LC and vice versa. The LOD in CE-MS was determined in the base peak electropherogram at ?1fmol, a value 2500 times smaller than the LOD found in nanoRP-HPLC-MS (3pmol). In nanoRP-HPLC-MS only 0.2% of the extrapolated CE-MS signal for a 25ng aviptadil load was observed. We conclude that both, the LOD as well as the impurity profile of aviptadil, as analyzed by nanoRP-HPLC are influenced by both, the ligand-derivatized silica matrix and the flow-rate. Peptides may disappear completely and their variable emergence may lead to the determination of incorrect ratios as present in the sample. PMID:24176753

Gross, Peter C; Burkart, Sonja C; Müller, Rolf

2014-01-01

39

RP-HPLC Method Development and Validation for Simultaneous Estimation of Atorvastatin Calcium and Pioglitazone Hydrochloride in Pharmaceutical Dosage Form.  

PubMed

A simple, selective, rapid, precise and economical reversed-phase high-performance liquid chromatographic (RP-HPLC) method has been developed for simultaneous estimation of atorvastatin calcium (ATV) and pioglitazone hydrochloride (PIO) from pharmaceutical formulation. The method is carried out on a C8 (25 cm × 4.6 mm i.d., 5 ?m) column with a mobile phase consisting of acetonitrile (ACN):water (pH adjusted to 6.2 using o-phosphoric acid) in the ratio of 45:55 (v/v). The retention time of ATV and PIO is 4.1 and 8.1 min, respectively, with the flow rate of 1 mL/min with diode array detector detection at 232 nm. The linear regression analysis data from the linearity plot showed good linear relationship with a correlation coefficient (R(2)) value for ATV and PIO of 0.9998 and 0.9997 in the concentration range of 10-80 µg mL(-1), respectively. The relative standard deviation for intraday precision has been found to be <2.0%. The method is validated according to the ICH guidelines. The developed method is validated in terms of specificity, selectivity, accuracy, precision, linearity, limit of detection, limit of quantitation and solution stability. The proposed method can be used for simultaneous estimation of these drugs in marketed dosage forms. PMID:24152592

Peraman, Ramalingam; Mallikarjuna, Sasikala; Ammineni, Pravalika; Kondreddy, Vinod Kumar

2014-10-01

40

Bioanalytical method development and validation for simultaneous estimation of cefixime and dicloxacillin by RP-HPLC in human plasma.  

PubMed

An accurate, rapid and simple reversed-phase high performance liquid chromatography (RP-HPLC) bioanalytical method was developed and validated for simultaneous estimation of cefixime, dicloxacillin in human plasma using ezetimibe as an internal standard. The cefixime, dicloxacillin and internal standard were extracted by liquid-liquid extraction technique. Chromatographic separation is accomplished using CAPCELL PAK C18 (4.6 mm × 250 mm, 5 m) analytical column. The mobile phase consisted of phosphate buffer, acetonitrile and methanol in 42:55:03 proportions. Detection and quantification were performed by UV/Vis detection at 225 nm. The lower limit of quantification was 0.5 µg mL(-1) for both cefixime and dicloxacillin in human plasma. The calibration curves were linear over the concentration range 0.5 to 40 µg mL(-1) for both drugs in human plasma. The method was quantitatively evaluated in terms of linearity, precision, accuracy, recovery, selectivity, and stability. The method was found to be simple, convenient and suitable for the analysis of cefixime and dicloxacillin from biological fluids. PMID:25286213

Bhinge, Somnath D; Malipatil, Sharangouda M; Sonawane, Lalit V

2014-01-01

41

Development and validation of RP HPLC method for determination of betamethasone dipropionate in gingival crevicular fluid.  

PubMed

Abstract A simple RP HPLC method for quantification of betamethasone dipropionate (BDP) in gingival crevicular fluid (GCF) has been developed and validated. GCF represents a valuable matrix for therapeutic monitoring of drugs used in the treatment of periodontal disease. The proposed method involves single step extraction for sample preparation. The calibration curve for BDP was linear over the concentration range of 0.10-2.00 ?g mL?¹ (R² = 0.9971). RSD values of intra- and inter-day precision ranged 2.2-4.5 and 1.6-5.7 %, while accuracy values were higher than 96.6 and 97.0 %, respectively. The described method can be successfully applied for determination of betamethasone concentrations in GCF obtained from patients with chronic periodontitis after local treatment with BDP cream 0.5 mg g?¹. PMID:24152901

Bogdanovska, Liljana; Popovska, Mirjana; Dimitrovska, Aneta; Petkovska, Rumenka

2013-09-01

42

Stability-indicating HPLC method for the determination of cefquinome sulfate.  

PubMed

A novel and sensitive stability-indicating RP-HPLC method for the quantitative determination of cefquinome sulfate has been developed. Chromatographic separation and quantitative determination were performed using a high-performance liquid chromatograph with UV detection. As the stationary phase a LiChroCART RP-18 column (5 microm particle size, 125 mm x 4 mm, Merck, Darmstadt, Germany) was used. The mobile phase consisted of 10 volumes of acetonitrile and 90 volumes of an 0.02 M phosphate buffer (pH = 7.0). The flow rate of the mobile phase was 1.0 mL/min. The eluents were monitored by a UV-VIS detector at 268 nm. The drug was subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal degradation. Significant degradation was found under basic, oxidizing stress and UV light. The developed method was validated with respect to linearity, accuracy, precision and robustness. PMID:25272644

Do?ha?, Agnieszka; Jelil?ska, Anna; Manuszewska, Monika

2014-01-01

43

The RP-HPLC method for simultaneous estimation of esomeprazole and naproxen in binary combination  

PubMed Central

Objective: A simple, precise, reliable, rapid, sensitive and validated RP-HPLC method has been developed to determine esomeprazole magnesium trihydrate (ESO) and naproxen (NAP) in synthetic mixture form. Materials and Methods: Chromatographic separation achieved isocratically on Phenomenex, Luna C18 column (5 ?m, 150mm × 4.60mm) and acetonitrile: phosphate buffer (pH 7.0) in the ratio of 50:50 (v/v) as the mobile phase, at a flow rate of 0.5 ml/min. Detection was carried out at 300 nm. The retention times for NAP and ESO was found to be 2.67 ±0.014 and 5.65 ±0.09 min respectively. Parameters such as linearity, precision, accuracy, recovery, specificity and ruggedness are studied as reported in the ICH guidelines. Results: The method was linear in the concentration range of 50-250 ?g/ml for NAP and 2-10 ?g/ml for ESO with correlation coefficient of 0.999 and 0.998 respectively. The mean recoveries obtained for NAP and ESO were 100.01% and 97.76 % respectively and RSD was less than 2. The correlation coefficients for all components are close to 1. Conclusions: Developed method was found to be accurate, precise, selective and rapid for simultaneous estimation of NAP and ESO. PMID:23781450

Jain, Deepak Kumar; Jain, Nitesh; Charde, Rita; Jain, Nilesh

2011-01-01

44

Quantification of allantoin in various Zea mays L. hybrids by RP-HPLC with UV detection.  

PubMed

A RP-HPLC method for quantification of allantoin in silk of fifteen maize hybrids (Zea mays L., Poaceae) was described. Following extraction of the plant material with an acetone-water (7:3, VN) mixture, filtration and dilution, the extracts were analyzed without previous chemical derivatization. Separation and quantification were achieved using an Alltech Econosil C18 column under isocratic conditions at 40 degrees C. The mobile phase flow (20% methanol--80% water with 5 mM sodium laurylsulfate added at pH 2.5, adjusted with 85% orthophosphoric acid; pH of water phase was finally adjusted at 6.0 by addition of triethylamine) was maintained at 1.0 mL/min. Column effluent was monitored at 235 nm. This simple procedure afforded efficient separation and quantification of allantoin in plant material, without interference of polyphenols or other plant constituents of medium to high polarity, or similar UV absorption. Our study revealed that the silk of all investigated maize hybrids could be considered relatively rich in allantoin, covering the concentration range between 215 and 289 mg per 100 g of dry plant material. PMID:15296088

Maksimovi?, Z; Malenovi?, A; Janci?, B; Kovacevi?, N

2004-07-01

45

Ripening of Ossau-Iraty cheese: determination of free amino acids by RP-HPLC and of total free amino acids by the TNBS method  

Microsoft Academic Search

The free amino acids and sulphosalicylic acid-soluble N fraction in the French ewes’-milk cheese, Ossau-Iraty, were determined to evaluate the degree of proteolysis during ripening of the cheese. RP-HPLC was used to assess the free amino acids, the trinitrobenzenesulphonic acid method to assess the sulphosalicylic acid-soluble N fraction. The total free amino acids content as determined by RP-HPLC ranged from

J. M Izco; P Torre; Y Barcina

2000-01-01

46

Development and validation of stability-indicating HPLC method for simultaneous determination of meropenem and potassium clavulanate.  

PubMed

A stability-indicating LC assay method was developed and validated for a simultaneous determination of meropenem and potassium clavulanate in the presence of degradation products formed during acid-base hydrolysis, oxidation and thermolysis. The isocratic RP-HPLC method was developed with a LiChrospher RP-18 (250 mm x 4.6 mm, 5 microm) column and gradient elution of 12 mmol/L ammonium acetate and acetonitrile. The flow rate of the mobile phase was 1.0 mL/min, the detection wavelength 220 nm and the temperature 303 K. The method was validated with regard to linearity, accuracy, precision, selectivity and robustness, and was applied successfully for the determination of meropenem and potassium clavulanate separately as well as jointly in pharmaceutical formulations. PMID:25272645

Zalewski, Przemys?aw; Cielecka-Piontek, Judyta; Paczkowska, Magdalena

2014-01-01

47

Quantization of Dextromethorphan and Levocetirizine in Combined Dosage form Using a Novel Validated RP-HPLC Method.  

PubMed

The present study reveals a simple isocratic RP-HPLC method for the simultaneous determination of dextromethorphan hydrobromide and levocetirizine dihydrochloride in a cough syrup. The separation of these compounds was achieved within 10 min on a Phenomenex (USA) C(18) analytical column, 250×4.0 mm i.d., using an isocratic mobile phase consisting of potassium dihydrogen phosphate buffer (pH 2.5) - acetonitrile- tetrahydrofuran (70:25:5, v/v/v). The analysis was performed at a flow rate of 1.2 ml/min and at a detection wavelength of 232 nm. Percentage recovery and RSD were 100.36% and 0.05% for levocetirizine dihydrochloride, 100.35% and 0.27% for dextromethorphan hydrobromide respectively. Quantification of the components in syrup formulation was calculated against the peak areas of freshly prepared standard solutions. The method was validated as per ICH guidelines. PMID:23204629

Joshi, Shalini; Bhatia, C; Bal, C S; Rawat, M S M

2012-01-01

48

Quantization of Dextromethorphan and Levocetirizine in Combined Dosage form Using a Novel Validated RP-HPLC Method  

PubMed Central

The present study reveals a simple isocratic RP-HPLC method for the simultaneous determination of dextromethorphan hydrobromide and levocetirizine dihydrochloride in a cough syrup. The separation of these compounds was achieved within 10 min on a Phenomenex (USA) C18 analytical column, 250×4.0 mm i.d., using an isocratic mobile phase consisting of potassium dihydrogen phosphate buffer (pH 2.5) - acetonitrile- tetrahydrofuran (70:25:5, v/v/v). The analysis was performed at a flow rate of 1.2 ml/min and at a detection wavelength of 232 nm. Percentage recovery and RSD were 100.36% and 0.05% for levocetirizine dihydrochloride, 100.35% and 0.27% for dextromethorphan hydrobromide respectively. Quantification of the components in syrup formulation was calculated against the peak areas of freshly prepared standard solutions. The method was validated as per ICH guidelines. PMID:23204629

Joshi, Shalini; Bhatia, C.; Bal, C. S.; Rawat, M. S. M.

2012-01-01

49

RP-HPLC method for simultaneous determination of butenafine hydrochloride and betamethasone dipropionate in a cream formulation.  

PubMed

An RP-HPLC method has been developed for the simultaneous determination of butenafine hydrochloride and betamethasone dipropionate on an Inertsil C18 column (250 x 4.6 mm id) using a mobile phase gradient consisting of methanol and water at a flow rate of 1 mL/min. Detection was carried out at 254 nm. Retention times of betamethasone dipropionate and butenafine hydrochloride were 4.82 (+/- 0.80) and 16.18 (+/- 0.17) min, respectively. The method was validated with respect to specificity, linearity, accuracy, precision, ruggedness, and robustness. This method is simple, precise, and sensitive, and applicable for the simultaneous quantification of butenafine hydrochloride and betamethasone dipropionate in a cream formulation. PMID:21391486

Bhosale, Suryakant D; Rajput, Sadhana J

2011-01-01

50

Bioactive compounds, RP-HPLC analysis of phenolics, and antioxidant activity of some Portuguese shrub species extracts.  

PubMed

In the ecosystem of Serra Da Estrela, some plant species have the potential to be used as raw material for extraction of bioactive products. The goal of this work was to determine the phenolic, flavonoid, tannin and alkaloid contents of the methanolic extracts of some shrubs (Echinospartum ibericum, Pterospartum tridentatum, Juniperus communis, Ruscus aculeatus, Rubus ulmifolius, Hakea sericea, Cytisus multiflorus, Crataegus monogyna, Erica arborea and Ipomoea acuminata), and then to correlate the phenolic compounds and flavonoids with the antioxidant activity of each extract. The Folin-Ciocalteu's method was used for the determination of total phenols, and tannins were then precipitated with polyvinylpolypyrrolidone (PVPP); a colorimetric method with aluminum chloride was used for the determination of flavonoids, and a Dragendorff's reagent method was used for total alkaloid estimation. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) and beta-carotene bleaching tests were used to assess the antioxidant activity of extracts. The identification of phenolic compounds present in extracts was performed using RP-HPLC. A positive linear correlation between antioxidant activity index and total phenolic content of methanolic extracts was observed. The RP-HPLC procedure showed that the most common compounds were ferulic and ellagic acids and quercetin. Most of the studied shrubs have significant antioxidant properties that are probably due to the existence of phenolic compounds in the extracts. It is noteworthy to emphasize that for Echinospartum ibericum, Hakea sericea and Ipomoea acuminata, to the best of our knowledge, no phytochemical studies have been undertaken nor their use in traditional medicine been described. PMID:22312726

Luís, Angelo; Domingues, Fernanda; Duarte, Ana Paula

2011-12-01

51

Extraction and RP-HPLC determination of taxol in rat plasma, cell culture and quality control samples  

PubMed Central

A rapid, sensitive, selective and validated reverse phase high-performance liquid chromatography (RP-HPLC) method for the estimation of paclitaxel in micro-sample of rat plasma and in culture of cancer cells was performed in this study. The mobile phase consisted of an optimized mixture of methanol:water: trifluroacetic acid (80: 20: 0.1, v/v/v). Column elution at a flow rate of 1 mL/minute with UV detection at 225 nm at room temperature was used. The RP-HPLC method was successfully applied for the determination of paclitaxel in plasma samples and in culture of cancer cells with nano-quantity of estimation. The validation studies were performed in accordance with the International Conference on Harmonization (ICH) guidelines. The intra- and inter-day precision showed that the coefficients of variation ranged from 1.07% to 4.27% at different levels of concentrations. To the best of our knowledge, this study also reported for the first time the optimization of different solvents for effective extraction of paclitaxel wherein tert.-butyl methyl ether (TBME): diethyl ether (DEE) in 50: 50 v/v composition was found most efficient with extraction efficiency ranging between 77.99% and 91.74% and between 76.14 and 93.66% in the plasma and cell culture, respectively. This proposed method was successfully applied to study the pharmacokinetics of paclitaxel and the influence of verapamil and all-trans retinoic acid (atRA) on paclitaxel pharmacokinetics in rat models. This proposed method might emerge as a valuable aid in the laboratory monitoring of paclitaxel in a variety of in vitro as well as in vivo scenarios. PMID:24086173

Tekade, Rakesh Kumar; D'Emanuele, Antony; Elhissi, Abdelbary; Agrawal, Ashish; Jain, Anurekha; Arafat, Basel Tawfiq; Jain, Narendra Kumar

2013-01-01

52

RP-HPLC method using one marker for quantification of four podophyllum lignans in medicinal plants.  

PubMed

A high-performance liquid chromatographic method using a single standard has been established for the quantitative analysis of four podophyllum lignans in Dysosma versipellis (Hance) M. Cheng and Podophyllum emodi Wall. Var. chinesis Sprague. The method involved the quantitative analysis of multiple components by a single marker. The chromatographic method was validated for linearity and range, limit of detection and qualification, precision, stability, reproducibility and robustness. Relative correcting factors were calculated and examined by five concentrations of four podophyllum lignans, two high-performance liquid chromatographic systems and three chromatographic columns. The method was applied to analyze 10 batches of samples. The quantitative results were compared with the results by an external standard method through intra-class coefficient, which indicated that the established method was reliable for the determination of the four podophyllum lignans in the two medicinal plants. PMID:23766105

Lu, Ningwei; An, Qiong; Li, Ning; Dong, Yuming

2014-07-01

53

Determination of seven phenolic compounds in Rhizoma Sparganii by RP-HPLC.  

PubMed

A reversed-phase high-performance liquid chromatographic method was developed for the simultaneous quantification of seven phenolic compounds from Rhizoma Sparganii. The samples were separated on a Waters SunFire C18 column with a temperature of 30°C. Gradient elution was applied, using 0.8% acetic acid (solvent A) and methanol (solvent B) with a flow rate of 1.0 mL/min, and detection wavelength was 280 nm. The validation of the method included linearity, precision, repeatability, stability and recovery. The calibration curves showed good linear regression (R(2) > 0.9996) within the test range. The developed method indicated good precision and accuracy, with the overall intra-day and inter-day variation at less than 3%. The range of recoveries for the seven analytes was 95.34-100.06% with relative standard deviation < 3.08 %. The established method was successfully applied for the determination of seven phenolic compounds in 12 batches of Rhizoma Sparganii. The study may be useful in the quality evaluation of Rhizoma Sparganii, and can provide technical support for pharmacological and clinical research of related drugs. PMID:23013896

Wang, Xinsheng; Wu, Qi-nan; Wu, Yanfang; Wu, Chengying; Yue, Wei; Liang, Qiaoli

2013-04-01

54

Methodology for a rapid and simultaneous determination of total cysteine, homocysteine, cysteinylglycine and glutathione in plasma by isocratic RP-HPLC.  

PubMed

Alterations in the plasma aminothiols levels can be considered as important biomarkers for the diagnosis and screening of several human disorders, namely cardiovascular diseases. We aimed to optimize a rapid, sensitive and accurate RP-HPLC methodology with fluorescence detection, for the simultaneous determination of the total concentrations of cysteine, homocysteine, cysteinylglycine and glutathione in blood plasma, as well as its application to the evaluation of those thiols levels in plasma of a group of Azorean subjects. Aminothiols were reduced with tri-n-butylphosphine and derivatized with a thiol-specific fluorogenic reagent ammonium 7-fluorobenzo-2-oxa-1,3-diazole-4-sulphonate. The thiols adducts were separated by an isocratic elution on a Platinum EPS C18 analytical column (53mm×7mm I.D., 3?m) using a phosphate buffer containing 4% of acetonitrile as a mobile phase. Results indicated an excellent linearity for all the analytes over their respective concentration ranges with correlation coefficients (r(2)) ?0.99. The LOD for the four plasma thiols was lower than 0.10?mol/L, while LOQ varied from 0.5 to 15?mol/L. For both intra- and inter-day precision, the RSD (%) values were lower than 1.9%, and the CV (%) values were found under 0.5%. The recovery ranged from 92% to 100% indicating a high degree of the method's accuracy. This method allows a simultaneous, complete analysis of the four plasma aminothiols and the internal standard in 6min. By reducing the total run time, a larger number of analysis can be performed daily. PMID:23217300

Ferin, Rita; Pavão, Maria Leonor; Baptista, José

2012-12-12

55

Simple RP-HPLC method for determination of triple drug combination of valsartan, amlodipine and hydrochlorothiazide in human plasma.  

PubMed

A simple RP-HPLC method for the quantification of valsartan (VAL), amlodipine (AML) and hydrochlorothiazide (HCT) in human plasma was developed and validated. VAL, AML and HCT were resolved using a Gemini C18 column and mobile phase gradient starting from 20 % acetonitrile and 80 % 10 mmol L(-1) ammonium formate (V/V, pH 3.5 ± 0.2, by formic acid) to 70 % acetonitrile and 30 % 10 mmol L(-1) ammonium formate, over 20 minutes, with a flow rate of 1 mL min(-1). The samples were purified by protein precipitation and extraction. Telmisartan was used as internal standard. The method was validated according to USFDA and EMEA guidelines with good reproducibility and linear responses R = 0.9985 (VAL), 0.9964 (AML), and 0.9971 (HCT). RSDs of intra- and inter-day precision ranged 2.2-8.1 and 4.6-11.7 %, respectively, for all three drugs. Mean extraction recoveries of three QCs for the triple drug combination were 76.5 (VAL), 72.0 (AML) and 73.0 (HCT) % for human plasma. Although the LC-MS/MS method is more sensitive than HPLC, HPLC is still suitable for preliminary pharmacokinetic study. The experiments performed demostrated that simultaneous determination of all components of the triple drug combination in human plasma can be done by this method. Proposed method can be also used for guidance to the LC-MS/MS method. PMID:22472448

Sharma, Ritesh N; Pancholi, Shyam Sunder

2012-03-01

56

Development and validation of RP-HPLC method for estimation of ethacridine lactate in bulk and in pharmaceutical formulation  

PubMed Central

A new simple, precise, accurate and selective RP-HPLC method has been developed and validated for estimation of Ethacridine lactate in pharmaceutical formulation. The method was carried out on a Qualisil RP C-18 (250 mm × 4.6 mm, 5 ?m) column with a mobile phase consisting of methanol: water (60:40 v/v), pH adjusted to 2.8 with ortho-phosphoric acid and flow rate of 1.0 mL/min. Detection was carried out at 271 nm. The retention time for ethacridine lactate was found to be 4.41 min. The ethacridine lactate followed linearity in the concentration range of 2- 12 ?g/mL (r2= 0.9980). The amount of the drug estimated by proposed method was found to be in good agreement with label claim. The developed method was validated for sensitivity, accuracy, precision, ruggedness and robustness. The LOD and LOQ were found to be 0.11 and 0.33 ?g. The proposed method can be used for routine analysis of ethacridine lactate in bulk drug and pharmaceutical formulation. PMID:23781440

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

2011-01-01

57

Development and validation of RP-HPLC method for estimation of ethacridine lactate in bulk and in pharmaceutical formulation.  

PubMed

A new simple, precise, accurate and selective RP-HPLC method has been developed and validated for estimation of Ethacridine lactate in pharmaceutical formulation. The method was carried out on a Qualisil RP C-18 (250 mm × 4.6 mm, 5 ?m) column with a mobile phase consisting of methanol: water (60:40 v/v), pH adjusted to 2.8 with ortho-phosphoric acid and flow rate of 1.0 mL/min. Detection was carried out at 271 nm. The retention time for ethacridine lactate was found to be 4.41 min. The ethacridine lactate followed linearity in the concentration range of 2- 12 ?g/mL (r(2)= 0.9980). The amount of the drug estimated by proposed method was found to be in good agreement with label claim. The developed method was validated for sensitivity, accuracy, precision, ruggedness and robustness. The LOD and LOQ were found to be 0.11 and 0.33 ?g. The proposed method can be used for routine analysis of ethacridine lactate in bulk drug and pharmaceutical formulation. PMID:23781440

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

2011-04-01

58

A Validated RP HPLC-PAD Method for the Determination of Hederacoside C in Ivy-Thyme Cough Syrup  

PubMed Central

A simple reversed phase high-performance liquid chromatographic (RP-HPLC) method coupled with a photodiode array detector (PAD) has been developed and validated for the analysis of hederacoside C, the marker of ivy plant, in Ivy-Thyme cough syrup. Separation of hederacoside C was achieved using a Phenomenex-Gemini C18 column isothermally at 40°C. A mobile phase system constituted of solvent A (water: acetonitrile: orthophosphoric acid (85%), 860?:?140?:?2?v/v) and solvent B (acetonitrile: orthophosphoric acid (85%), 998?:?2?v/v) was used, at gradient conditions, at a flow rate of 1.5?mL/min. Analysis was performed using UV-detection (205?nm). The method was linear over the range (0.03–0.15)?mg/mL of hederacoside C (r = 0.9992). Repeatability and intermediate precision were acceptable (RSD <2%). Limits of detection (LOD) and quantitation (LOQ) were 0.011 and 0.032?mg/mL, respectively. Percentage recovery was found to lie between 99.69% and 100.90% (RSD <2%). The method was also proved to be specific (peak-purity coefficient = 0.996). PMID:20862201

Khdair, Ayman; Mohammad, Mohammad K.; Tawaha, Khaled; Al-Hamarsheh, Eman; AlKhatib, Hatim S.; Al-khalidi, Bashar; Bustanji, Yasser; Najjar, Samer; Hudaib, Mohammad

2010-01-01

59

Simultaneous determination of 10 active components in traditional Chinese medicine "YIGONG" capsule by RP-HPLC-DAD.  

PubMed

A simple, reliable and accurate method for the simultaneous separation and determination of 10 active components (psoralen, isopsoralen, emodin, oleanolic acid, stachydrine hydrochloride, ammonium glycyrrhizinate, glycyrrhizinate, schizandrol, imperatorin and isoimperatorin) in traditional Chinese medicine "YIGONG" capsule was developed using reverse phase high-performance liquid chromatography (RP-HPLC) coupled with diode array detection. The chromatographic separation was performed on a Eurospher C(18) column (250 mm x 4.6 mm i.d. with 5.0 microm particle size) with a acetonitrile-water gradient containing 0.5% (v/v) aqueous phosphoric acid as mobile phase. Two detection wavelengths (210 and 250 nm) were utilized for the quantitative analysis due to the different UV spectra of these components. Good linear behaviors over the investigated concentration ranges were observed with the values of R(2) higher than 0.999 for all the analytes. The recoveries, measured at three concentration levels, varied from 95.0 to 105.3%. The validated method was successfully applied to the simultaneously determination of these active components in "YIGONG" capsule from different production batches. PMID:18314288

Feng, Chao; Cai, Ya-Ling; Ruan, Jin-Lan

2008-06-01

60

RP-HPLC-ESI-MS characterization of novel peptide fragments related to rat parotid secretory protein in parasympathetic induced saliva.  

PubMed

Two peptides (MW 1211.7 and 928.5 Da) were detected by RP-HPLC-ESI-MS analysis of parotid saliva secreted upon continuous parasympathetic stimulation. The peptide with the higher mass (PSPFr-A) corresponded to the N-terminal dodecapeptide (Fragment 1-12) of rat parotid secretory protein (PSP), while the peptide with the lower mass (PSPFr-B) corresponded to the 4-12 fragment of the same protein. During stimulation, the PSPFr-A secretion increased, while the PSPFr-B secretion decreased (HPLC-ESI-MS). In the presence of cycloheximide, PSPFr-A was not demonstrated, while the PSPFr-B secretion decreased. In the presence of aprotinin, the PSPFr-B secretion was almost abolished, while the PSPFr-A secretion increased to higher levels than those observed in the absence of the inhibitor. In vitro perfusion, with artificial solution, of stimulated rat parotid glands excluded that the fragments were derived from the circulation. Neither peptide occurred in enriched granule preparations from unstimulated glands. The results suggest that at least two pathways--granular and vesicular--are responsible for the generation of the two peptides. PSPFr-A is the first cleavage product in both pathways. PRPFr-B is probably generated from granular PSPFr-A only and, at the end of the granule mediated pathway, by the action of an enzyme of the serine protease class. PMID:19642100

Ekström, Jörgen; Murakami, Masataka; Inzitari, Rosanna; Khosravani, Nina; Fanali, Chiara; Cabras, Tiziana; Fujita-Yoshigaki, Junko; Sugiya, Hiorshi; Messana, Irene; Castagnola, Massimo

2009-09-01

61

A rp-HPLC method for the assay of cefpirome and its application in drug-metal interaction studies.  

PubMed

An accurate, sensitive and least time consuming RP-HPLC method for the estimation of cefpirome in the presence of essential and trace metal has been developed and validated. Cefpirome was eluted from a B144A, OD-5-100, C(18) (150 x 4.6 mm) column at room temperature with a mobile phase consisting of MeOH:H2O (15:85, % v/v) at a flow rate of 1 ml/minute, while UV detection was performed at 265 nm. The detection limit of cefpirome was 10 ng. Drug metal interaction studies were carried out at 37 degrees C to monitor the complexation of drug with metal ions. These studies were beneficial to determine the drug in therapeutic concentrations inside human body as well as its complexation with metal cations. The metals essential to human body like Mg(II), Ca(II), Cr(II), Mn(II), Fe (III), Co(II), Ni(II), Cu(II), Zn(II) & Cd(II) were in the form of chlorides. The carboxylic group of the dehydrothiazine ring has more binding capacity relative to other group that augments the drug complexes with essential and trace elements. The established HPLC method is rapid, accurate, and selective, because of its sensitivity and reproducibility. The order of complexation was ferric>chromium>copper>nickel>cadmium>zinc>magnesium>manganese>calcium>cobalt. PMID:16632451

Arayne, M Saeed; Sultana, Najma; Nawaz, M

2006-01-01

62

Rat neuropeptidomics by LC-MS/MS and MALDI-FTMS: Enhanced dissection and extraction techniques coupled with 2D RP-RP HPLC.  

PubMed

Recently developed sample preparation techniques employing microwave irradiation have enabled the comprehensive study of endogenous mammalian neuropeptides. These methods reduce interference from post-mortem protein degradation by deactivating proteases via heat denaturation. Alternatively, we have developed a protocol using cryostat dissection and a boiling extraction buffer to achieve a similar effect. This novel methodology greatly reduces post-mortem protein contamination and increases neuropeptide identification without the use of specialized equipment. In addition, a 2D HPLC scheme employing differential pH selectivity in the first and second dimensions has been used to enhance neuropeptidome coverage. By using our novel dissection protocol in tandem with 2D RP-RP HPLC, we were able to identify a total of 56 peptides from known neuropeptide precursors, including 17 previously unidentified peptides. The use of cryostat dissection and two-dimensional RP-RP HPLC enhances the detection of novel neuropeptides by deactivating proteases and reducing sample complexity. PMID:17137338

Dowell, James A; Heyden, William Vander; Li, Lingjun

2006-12-01

63

Determination of n-octanol\\/water partition coefficient for DDT-related compounds by RP-HPLC with a novel dual-point retention time correction  

Microsoft Academic Search

n-Octanol\\/water partition coefficients (P) for DDTs and dicofol were determined by reversed-phase high performance liquid chromatography (RP-HPLC) on a C18 column using methanol–water mixture as mobile phase. A dual-point retention time correction (DP-RTC) was proposed to rectify chromatographic retention time (tR) shift resulted from stationary phase aging. Based on this correction, the relationship between logP and logkw, the logarithm of

Shu-ying Han; Jun-qin Qiao; Yun-yang Zhang; Li-li Yang; Hong-zhen Lian; Xin Ge; Hong-yuan Chen

2011-01-01

64

RP-HPLC determination and pharmacokinetic study of mangiferin in rat plasma after taking traditional chinese medicinal-preparation: Zhimu decoction  

Microsoft Academic Search

Summary  A sensitive, simple, and accurate method for determination and pharmacokinetic study of mangiferin in rat plasma was developed\\u000a using RP-HPLC with UV detection. Sample preparations were carried out by protein precipitation with the addition of acetonitrile,\\u000a followed by evaporation of the acetonitrile to dryness. The resultant residue was then reconstituted in mobile phase and injected\\u000a onto a Hypersil C18 analytical

Y.-J. Li; K.-S. Bi

2003-01-01

65

Simultaneous Determination of Nine Water and Fat Soluble Vitamins After SPE Separation and RP-HPLC Analysis in Pharmaceutical Preparations and Biological Fluids  

Microsoft Academic Search

An automated reversed phase high performance liquid-chromatography (RP-HPLC) method is described, for the simultaneous analysis of water soluble [ascorbic acid (C), nicotinic acid, nicotinamide, folic acid, cyanocobalamine (B12), and riboflavin (B2)] and fat soluble (retinol, ?-tocopherol, ?-tocopherol acetate) vitamins. The compounds are separated after solid-phase extraction (SPE) on C18 cartridges, where water soluble vitamins pass unretained, while fat soluble vitamins

I. N. Papadoyannis; G. K. Tsioni; V. F. Samanidou

1997-01-01

66

Comparative Study of Ion Interaction Reagents for the Separation of Lanthanides by Reversed-Phase High Performance Liquid Chromatography (RP-HPLC)  

Microsoft Academic Search

A study of two ion interaction reagents (IIRs) viz. n-octadecane sulphonate (C18-sulphonate) and eicosyl sulphate (C20-sulphate) was carried out for the separation of lanthanides by reversed-phase high performance liquid chromatography (RP–HPLC). The objective of the study was to identify a suitable IIR offering long term adsorption onto the RP column, thereby obviating the need to introduce the IIR in the

P. G. Jaison; Pranaw Kumar; Vijay M. Telmore; Suresh K. Aggarwal

2009-01-01

67

RP-HPLC Method for Simultaneous Estimation of Nitazoxanide and Ofloxacin in Tablets.  

PubMed

A reverse phase high performance liquid chromatography method was developed for simultaneous estimation of nitazoxanide and ofloxacin in tablet formulation. The separation and quantification was achieved by Hiq Sil C(18)V Size 4.6 mm Ø (*)250 mm column in isocratic mode, with mobile phase consisting of acetonitrile-methanol-0.4 M citric acid, (60:30:10, v/v/v). Citric acid used to stabilize nitazoxanide and ofloxacin in mobile phase. The mobile phase was pumped at a rate of 0.6 ml/min and the detection was carried out at 304 nm. The retention time of ofloxacin and nitazoxanide was found to be 3.122 and 5.902 min, respectively. The method was validated for linearity, accuracy, and precision. Linearity for ofloxacin and nitazoxanide were in the range 2-36 ?g/ml and 5-90 ?g/ml, respectively. The developed method was found to be accurate, precise and selective for simultaneous estimation of ofloxacin and nitazoxanide in tablets. PMID:22131628

Sharma, S; Bhandari, A; Choudhary, V R; Rajpurohit, H; Khandelwal, P

2011-01-01

68

A RP-HPLC method for quantification of diclofenac sodium released from biological macromolecules.  

PubMed

Interpenetrating network (IPN) microbeads of sodium carboxymethyl locust bean gum (SCMLBG) and sodium carboxymethyl cellulose (SCMC) containing diclofenac sodium (DS), a nonsteroidal anti-inflammatory drug, were prepared by single water-in-water (w/w) emulsion gelation process using AlCl3 as cross-linking agent in a complete aqueous environment. Pharmacokinetic study of these IPN microbeads was then carried out by a simple and feasible high-performance liquid chromatographic method with UV detection which was developed and validated for the quantification of diclofenac sodium in rabbit plasma. The chromatographic separation was carried out in a Hypersil BDS, C18 column (250 mm × 4.6 mm; 5 m). The mobile phase was a mixture of acetonitrile and methanol (70:30, v/v) at a flow rate of 1.0 ml/min. The UV detection was set at 276 nm. The extraction recovery of diclofenac sodium in plasma of three quality control (QC) samples was ranged from 81.52% to 95.29%. The calibration curve was linear in the concentration range of 20-1000 ng/ml with the correlation coefficient (r(2)) above 0.9951. The method was specific and sensitive with the limit of quantification of 20 ng/ml. In stability tests, diclofenac sodium in rabbit plasma was stable during storage and assay procedure. PMID:23567284

Bhattacharya, Shiv Sankar; Banerjee, Subham; Ghosh, Ashoke Kumar; Chattopadhyay, Pronobesh; Verma, Anurag; Ghosh, Amitava

2013-07-01

69

A validated stability-indicating liquid chromatographic method for determination of process related impurities and degradation behavior of Irbesartan in solid oral dosage.  

PubMed

The present work describes the development and validation of a stability-indicating RP-HPLC method for the estimation of degradation and process related impurities of Irbesartan, namely Impurity-1, Impurity-2, Impurity-3 and Impurity-4. The developed LC method was validated with respect to specificity, limit of detection and quantification, linearity, precision, accuracy and robustness. The chromatographic separation was achieved on Hypersil Octadecylsilyl (4.6 mm × 150 mm, 3 ?m) column by using mobile phase containing a gradient mixture of solvent A (0.55% v/v ortho-phosphoric acid, pH adjusted to 3.2 with triethyl amine) and B (95:5 v/v mixture of acetonitrile and solvent A) at a flow rate of 1.2 mL/min. The detection was carried out at a wavelength of 220 nm. During method validation parameter such as precision, linearity, accuracy, specificity, limit of detection and quantification were evaluated, which remained within acceptable limits. HPLC analytical method is linear, accurate, precise, robust and specific, being able to separate the main drug from its degradation products. The degradation products were well-resolved from the main peak and its impurities, thus proving the stability-indicating power of the method. The method is stability-indicating in nature and can be used for routine analysis of production samples and to check the stability of the Irbesartan HCl tablets. PMID:24695518

Goswami, Nishant

2014-01-01

70

A validated stability-indicating liquid chromatographic method for determination of process related impurities and degradation behavior of Irbesartan in solid oral dosage  

PubMed Central

The present work describes the development and validation of a stability-indicating RP-HPLC method for the estimation of degradation and process related impurities of Irbesartan, namely Impurity-1, Impurity-2, Impurity-3 and Impurity-4. The developed LC method was validated with respect to specificity, limit of detection and quantification, linearity, precision, accuracy and robustness. The chromatographic separation was achieved on Hypersil Octadecylsilyl (4.6 mm × 150 mm, 3 ?m) column by using mobile phase containing a gradient mixture of solvent A (0.55% v/v ortho-phosphoric acid, pH adjusted to 3.2 with triethyl amine) and B (95:5 v/v mixture of acetonitrile and solvent A) at a flow rate of 1.2 mL/min. The detection was carried out at a wavelength of 220 nm. During method validation parameter such as precision, linearity, accuracy, specificity, limit of detection and quantification were evaluated, which remained within acceptable limits. HPLC analytical method is linear, accurate, precise, robust and specific, being able to separate the main drug from its degradation products. The degradation products were well-resolved from the main peak and its impurities, thus proving the stability-indicating power of the method. The method is stability-indicating in nature and can be used for routine analysis of production samples and to check the stability of the Irbesartan HCl tablets. PMID:24695518

Goswami, Nishant

2014-01-01

71

Determination of copper, nickel, cobalt, silver, lead, cadmium, and mercury ions in water by solid-phase extraction and the RP-HPLC with UV-Vis detection  

Microsoft Academic Search

A new method for the simultaneous determination of seven heavy metal ions in water by solid-phase extraction and reversed-phase high-performance liquid chromatography (RP-HPLC) was developed. The copper, nickel, cobalt, silver, lead, cadmium, and mercury ions were pre-column derivatized with tetra(m-aminophenyl)porphyrin (Tm-APP) to form colored chelates. The metal-Tm-APP chelates in 100 mL of sample were preconcentrated to 1 mL by solid-phase

Qiufen Hu; Guangyu Yang; Yiyun Zhao; Jiayuan Yin

2003-01-01

72

A Rapid, Validated RP-HPLC Method for the Simultaneous Determination of Cleaning Validation and Cross-Contamination of 12 Beta-Lactam Compounds  

PubMed Central

The present work reports a rapid reversed-phase high-performance liquid chromatography (RP-HPLC) method for the simultaneous determination of 12 beta-lactam components for cleaning validation and cross-contamination. A strategic experimental approach was implemented for the method development. The desired chromatographic separation was achieved on a Symmetry C18 (4.6 X 75 mm, 3.5 ?m) column using gradient elution. The optimized mobile phase consisted of the buffer tetrabutylammonium hydroxide pH-6.8 and acetonitrile. The eluted compounds were monitored at 215 nm and 254 nm wavelength using a photodiode array detector. The developed method separated 12-beta-lactam compounds from each other within a run time of 50 min. The method is effective for the determination of cross-contamination of penicillin and cephalosporin production blocks. The present method is specific and a lower limit of quantification was determined on the basis of the signal-to-noise ratio method; it is 1 ?g/mL for all components. The developed RP-HPLC method was validated according to the International Conference on Harmonization (ICH) guidelines. PMID:23641335

Trivedi, Harshal Kanubhai; Kshtri, Nayan; Patel, Mukesh C.

2013-01-01

73

Quantitative Determination of three Angiotensin-II-receptor Antagonists in Presence of Hydrochlorothiazide by RP-HPLC in their Tablet Preparations  

PubMed Central

Losartan potassium, Valsartan , Telmisartan and Irbesartan are angiotensin-II-receptor antagonists (ARA II) group which used in treatment of hypertension alone or in combination with other drugs mainly Hydrochlorothiazide. RP- HPLC method was developed for the assay of three angiotensin-II-receptor antagonists (ARA-IIs) in presence of Hydrochlorothiazide. The method was performed by reversed phase high performance liquid chromatography using a mobile phase which is consisted of 0.025 M potassium dihydrogen phosphate (pH 6.0): acetonitrile = 65:35% with detection at 220 nm on an ACE C18 column (250 mm × 4.6 mm, 5 ?m) at flow rate 1.5 mL/min in an isocratic manner. The proposed method was validated according to ICH guidline in terms of linearity, accuracy, precision , robustness, limit of detection and limit of quantitation. PMID:24523743

Hafez, Hany Mohammed; Elshanawane, Abdullah Ahmed; Abdelaziz, Lobna Mohammed; Kamal, Magda Mohammed

2013-01-01

74

Development and Validation of a Stability-Indicating HPLC Method for the Simultaneous Determination of Sulfadiazine Sodium and Trimethoprim in Injectable Solution Formulation  

PubMed Central

A direct, precise, and stability-indicating HPLC method that is based on reversed-phase liquid chromatography (RP-HPLC) coupled with a photodiode array detector (PDA) was developed, optimized, and validated for the simultaneous determination of sulfadiazine sodium (SDZS) and Trimethoprim (TMP) in Bactizine® forte injectable solution. The separation was achieved using a C18 column (250 mm×4.6 mm i.d., 5 ?m particle size) at room temperature, and an isocratic mobile phase that consisted of a trinary solvent mixture of water–acetonitrile–triethylamine (838:160:2, v/v) at pH 5.5 ± 0.05. The mobile phase was delivered at 1.4 ml/min and the analytes were monitored at 254 nm. The effects of the operational chromatographic conditions on the peak’s USP tailing factor, column efficiency, and resolution were systematically optimized. Forced degradation experiments were carried out by exposing SDZS, TMP standards, and their formulation to thermal, photolytic, oxidative, and acid-base hydrolytic stress conditions. The method was successfully validated in accordance to International Conference on Harmonization (ICH) and United States Pharmacopoeia (USP34/NF29) guidelines and found to be suitable for the quantitative determination and stability of SDZS and TMP in Bactizine® forte injectable solution. PMID:23641336

Ghanem, Mashhour M.; Abu-Lafi, Saleh A.

2013-01-01

75

A validated RP-HPLC method for simultaneous determination of propranolol and valsartan in bulk drug and gel formulation  

PubMed Central

Objective: A simple, precise, and stability indicating high performance liquid chromatography (HPLC) method was developed and validated for the simultaneous determination of propranolol hydrochloride and valsartan in pharmaceutical dosage form. Materials and Methods: The method involves the use of easily available inexpensive laboratory reagents. The separation was achieved on Hypersil ODS C-18 column (250*4.6 mm, i.d., 5 ?m particle size) with isocratic flow with UV detector. The mobile phase at a flow rate of 1.0 mL/min consisted of acetonitrile, methanol, and 0.01 M disodium hydrogen phosphate (pH 3.5) in the ratio of 50:35:15 v/v. Results: A linear response was observed over the concentration range 5-50 ?g/mL of propranolol and the concentration range 4-32 ?g/mL of valsartan. Limit of detection and limit of quantitation for propranolol were 0.27 ?g/mL and 0.85 ?g/mL, and for valsartan were 0.45 ?g/mL and 1.39 ?g/mL, respectively. The method was successfully validated in accordance to ICH guidelines acceptance criteria for linearity, accuracy, precision, specificity, robustness. Conclusion: The analysis concluded that the method was selective for simultaneous estimation of propranolol and valsartan can be potentially used for the estimation of these drugs in combined dosage form. PMID:23559826

Imam, Syed Sarim; Ahad, Abdul; Aqil, Mohammed; Sultana, Yasmin; Ali, Asgar

2013-01-01

76

Development and Validation of a Stability-Indicating LC-Method for the Simultaneous Estimation of Levodropropizine, Chloropheniramine, Methylparaben, Propylparaben, and Levodropropizine Impurities  

PubMed Central

A simple, fast, and efficient RP-HPLC method has been developed and validated for the simultaneous estimation of Levodropropizine, Chloropheniramine, Methylparaben, Propylparaben, and the quantification of Levodropropizine impurities in the Reswas syrup dosage form. A gradient elution method was used for the separation of all the actives and Levodropropizine impurities by using the X-Bridge C18, 150 mm × 4.6 mm, 3.5 ?m column with a flow rate of 1.0 mL/min and detector wavelength at 223 nm. The mobile phase consisted of a potassium dihydrogen orthophosphate buffer and acetonitrile. All the peaks were symmetrical and well-resolved (resolution was greater than 2.5 for any pair of components) with a shorter run time. The limit of detection for Levodropropizine and its Impurity B was 0.07 ?g/ml & 0.05 ?g/ml, whereas the limit of quantification was 0.19 ?g/ml & 0.15 ?g/ml respectively. The method was validated in terms of precision, accuracy, linearity, robustness, and specificity. Degradation products resulting from the stress studies were well-resolved and did not interfere with the detection of Levodropropizine, Chloropheniramine, Methylparaben, Propylparaben, and Levodropropizine Impurity B, thus the test method is stability-indicating. Validation of the method was carried out as per International Conference on Harmonization (ICH) guidelines. PMID:23641334

Kumar, Palakurthi Ashok; Raju, Thummala Veera Raghava; Thirupathi, Dongala; Kumar, Ravindra; Shree, Jaya

2013-01-01

77

Evaluation of a Propolis Water Extract Using a Reliable RP-HPLC Methodology and In Vitro and In Vivo Efficacy and Safety Characterisation  

PubMed Central

Since the beginning of propolis research, several groups have studied its antibacterial, antifungal, and antiviral properties. However, most of these studies have only employed propolis ethanolic extract (PEE) leading to little knowledge about the biological activities of propolis water extract (PWE). Based on this, in a previous study, we demonstrated the anti-inflammatory and immunomodulatory activities of PWE. In order to better understand the equilibrium between effectiveness and toxicity, which is essential for a new medicine, the characteristics of PWE were analyzed. We developed and validated an RP-HPLC method to chemically characterize PWE and PEE and evaluated the in vitro antioxidant/antimicrobial activity for both extracts and the safety of PWE via determining genotoxic potential using in vitro and in vivo mammalian micronucleus assays. We have concluded that the proposed analytical methodology was reliable, and both extracts showed similar chemical composition. The extracts presented antioxidant and antimicrobial effects, while PWE demonstrated higher antioxidant activity and more efficacious for the most of the microorganisms tested than PEE. Finally, PWE was shown to be safe using micronucleus assays. PMID:23710228

Rocha, Bruno Alves; Bueno, Paula Carolina Pires; Vaz, Mirela Mara de Oliveira Lima Leite; Nascimento, Andresa Piacezzi; Ferreira, Nathalia Ursoli; Moreno, Gabriela de Padua; Rodrigues, Marina Rezende; Costa-Machado, Ana Rita de Mello; Barizon, Edna Aparecida; Campos, Jacqueline Costa Lima; de Oliveira, Pollyanna Francielli; Acesio, Nathalia de Oliveira; Martins, Sabrina de Paula Lima; Tavares, Denise Crispim; Berretta, Andresa Aparecida

2013-01-01

78

Ionic liquid-based dispersive liquid-liquid microextraction followed by RP-HPLC determination of saquinavir in rat serum: application to pharmacokinetics.  

PubMed

An ionic liquid-based dispersive liquid-liquid microextraction followed by RP-HPLC determination of the most commonly prescribed protease inhibitor, saquinavir, in rat plasma was developed and validated. The effects of different ionic liquids, dispersive solvents, extractant/disperser ratio and salt concentration on sample recovery and enrichment were studied. Among the ionic liquids investigated, 1-butyl-3-methylimidazolium hexafluorophosphate was found to be most effective for extraction of saquinavir from rat serum. The recovery was found to be 95% at an extractant/disperser ratio of 0.43 using 1-butyl-3-methylimidazolium hexafluorophosphate and methanol as extraction and dispersive solvents. The recovery was further enhanced to 99.5% by addition of 5.0% NaCl. A threefold enhancement in detection and quantification limits was achieved, at 0.01 and 0.03 µg/mL, compared with the conventional protein precipitation method. A linear relationship was observed in the range of 0.035-10.0 µg/mL with a correlation coefficient (r(2) ) of 0.9996. The method was validated and applied to study pharmacokinetics of saquinavir in rat serum. Copyright © 2014 John Wiley & Sons, Ltd. PMID:24944096

Ramisetti, Nageswara Rao; Nimmu, Narendra Varma; Challa, Gangu Naidu

2014-12-01

79

Simultaneous estimation of levodopa and carbidopa by RP-HPLC using a fluorescence detector: its application to a pharmaceutical dosage form.  

PubMed

A reverse-phase high-performance liquid chromatographic (RP-HPLC) method was developed and validated for the simultaneous estimation of levodopa and carbidopa in bulk and pharmaceutical formulations. Chromatographic separation was achieved by using a C18 reverse-phase column and a mixture of an aqueous phase (10?mM potassium dihydrogen phosphate buffer, pH?4.0) and methanol (90:10?v/v) as the mobile phase. Quantitative analysis of levodopa and carbidopa was performed using a fluorescence detector at an excitation wavelength of 280?nm and an emission wavelength of 310?nm. The method was linear between 5 and 500?ng/mL for both levodopa and carbidopa. The detection limits for levodopa and carbidopa were 0.30 and 0.60?ng/mL, respectively, whereas the quantitation limit was 0.80?ng/mL for levodopa and 1.2?ng/mL for carbidopa. The method demonstrated good and consistent recoveries (99.63-100.80% for levodopa and 98.97-100.94% for carbidopa) with low interday and intraday relative standard deviation. The validated method was successfully applied to quantify levodopa and carbidopa simultaneously in a pharmaceutical formulation. The method was found to be precise, sensitive and accurate for the simultaneous determination levodopa and carbidopa in bulk and pharmaceutical formulations. Copyright © 2014 John Wiley & Sons, Ltd. PMID:24399763

Raut, Prashant P; Charde, Shrikant Y

2014-11-01

80

A novel RP-HPLC method for simultaneous determination of potassium sorbate and sodium benzoate in soft drinks using C(18) -bonded monolithic silica column.  

PubMed

Potassium sorbate and sodium benzoate are food additives that are generally employed for prevention of food spoilage originating from bacteria, molds or yeasts. Although these compounds were generally recognized as safe due to their low risk of acute and chronic toxicity, they have limitations of usage to protect human health. Development and validation of a novel RP-HPLC method, in which a C(18) -bonded monolithic silica column was used as stationary phase to assay these compounds, is described for the first time. Aliquots of 10??L of samples were injected into chromatograph and eluted using phosphate buffer (0.025?M, pH 2.0)-water-acetonitrile (50:45:5, v/v/v) solution, which was pumped at the rate of 3.0?mL/min. To sharpen the peaks, 10?mM octylamine was added to the mobile phase. Potassium sorbate and sodium benzoate were detected at about 12(th) and 14(th) min, respectively, and quantified at 230?nm using photodiode array detector. A total of 41 samples were prepared by simply filtering through 0.45??m filters after sonication, and injected into the system without any pre-treatment steps. Applicability of the method was demonstrated by performing total procedure on samples of different brands and types, and their compliance to official regulations was assessed. PMID:21595030

Can, Nafiz O; Arli, Goksel; Lafci, Yigit

2011-05-19

81

The RP-HPLC measurement and QSPR analysis of logP(o/w) values of several Pt(II) complexes.  

PubMed

The n-octanol/water partition coefficient, logP(o/w), for a set of 24 Pt(II)-complexes was estimated by means of reversed-phase high performance liquid chromatography (RP-HPLC) technique using a C18 (ODS, octadecyl silane) column as a stationary phase and water/methanol mixtures as mobile phases. Based on the known logP(o/w) of several Pt(II)-complexes, we set a method to correlate the partition coefficient of this kind of complexes with the corresponding retention parameters. The best result was obtained from extrapolation to 0% of the organic modifier (MeOH) of the aqueous eluant. A quantitative structure-property relationship (QSPR) was constructed using molecular descriptors derived from density functional theory (DFT) calculations, which was found to correlate and predict these values with good accuracy. The use of DFT calculations is required because group-additive methods fail due to lack of values for appropriate fragments for many Pt(II)-complexes. PMID:16530269

Platts, James A; Oldfield, Steven P; Reif, Maria M; Palmucci, Alessandra; Gabano, Elisabetta; Osella, Domenico

2006-07-01

82

Development and Validation of RP-HPLC Method for the Simultaneous Estimation of Montelukast Sodium and Ebastine in Tablet Dosage Form.  

PubMed

A rapid and sensitive RP-HPLC method with UV detection (244 nm) for routine analysis of montelukast sodium and ebastine in a pharmaceutical formulation (Ebast-M) was developed. Chromatography was performed with mobile phase containing a mixture of methanol:acetonitrile:ammonium acetate (80:10:10, % v/v/v), pH of mobile phase was adjusted 5.5 using glacial acetic acid and flow rate was 1.2 ml/min. The method was validated for linearity, accuracy, robustness and intermediate precision. The linearity was established over the concentration range of 0.01-0.06 mg/ml for both drugs. The correlation coefficients (r (2)) for ebastine and montelukast were 0.9989 and 0.9955, respectively. Statistical analysis of the data showed that the method was precise, accurate, reproducible and selective for the analysis of ebastine and montelukast drugs. The method was successfully employed for the determination of ebastine and montelukast in commercially available tablet dosage form. PMID:24403662

Rana, N S; Rajesh, K S; Patel, Nikita N; Patel, P R; Limbachiya, U; Pasha, T Y

2013-09-01

83

Simultaneous determination of fangchinoline and tetrandrine in Stephania tetrandra S. Moore by using 1-alkyl-3-methylimidazolium-based ionic liquids as the RP-HPLC mobile phase additives.  

PubMed

A reversed phase high performance liquid chromatography (RP-HPLC) method for simultaneous determination of fangchinoline (FAN) and tetrandrine (TET) in Stephania tetrandra S. Moore was established by using 1-hexyl-3-methylimidazolium tetrafluoroborate as the mobile phase additives in this paper. Four types of 1-alkyl-3-methylimidazolium-based ionic liquids (ILs) were used as additives of the mobile phase to separate FAN and TET by RP-HPLC. The effects of the length of the alkyl group on the imidazolium ring and its counterion, the concentrations of IL and the pH of the mobile phase, which influenced the chromatographic behaviors of FAN and TET, were investigated in detail. The linearity, sensitivity, accuracy and repeatability of the proposed method were also investigated. The probable mechanism of the separation with ILs as the mobile phase additives was explored and discussed. PMID:23452799

Tang, Yan; Sun, Ailing; Liu, Renmin; Zhang, Yongqing

2013-03-12

84

Sensitive and selective method for the analysis of menthol from pharmaceutical products by RP-HPLC with refractive index detector  

PubMed Central

Objective: Liquid chromatography with refractive index (RI) detection has been found to be very useful for the determination of menthol from pharmaceutical products. A simple and rapid HPLC method has been developed for this purpose compared to conventional GC methods, requiring no special sample pretreatment for the determination of menthol from pharmaceutical products. Materials and Methods: A chromatographic separation was achieved on a Inertsil ODS 3V (4.6mm×250mm, 5?m) column using water : methanol (30:70 v/v) as a mobile phase, at a flow rate of 1.0 ml/min. Results: Method was validated as per ICH guidelines for various parameters such as precision, linearity, accuracy, solution stability, robustness, limit of detection and quantification. Results were found to be within acceptable limits. Conclusion: The method has been successfully applied for the quantification of menthol from syrup formulations. The developed method can be conveniently used by the quality control department to determine assay of menthol from pharmaceutical preparations. PMID:21180473

Shaikh, K. A.; Patil, Sachin D.

2010-01-01

85

A simple RP-HPLC method for the simultaneous quantitation of chlorocresol, mometasone furoate, and fusidic acid in creams.  

PubMed

A simple, specific, and precise high-performance liquid chromatographic method is developed and validated for the simultaneous determination of chlorocresol (CC), mometasone furoate (MF), and fusidic acid (FA) in a cream formulation. The isocratic mobile phase consists of 1.5% w/v aqueous ammonium acetate buffer-acetonitrile, 55:45 (v/v) of pH 3.8. The column contains octylsilyl chemically bonded to porous silica particle (Symmetry C8, 150x3.9 mm, 5 microm). The detection is carried out using variable wavelength UV-vis detector set at 240 nm. The solutions are chromatographed at a steady flow rate of 1.0 mL/min. The current method separates CC, MF, and FA in less than 8 min with good resolution and peak shapes, minimal tailing, and with retention factors between approximately 1 and 5. Linearity range and percent recoveries for CC, MF, and FA are 10-30, 10-30, and 200-600 microg/mL; and 100.31%, 100.38%, and 100.34%, respectively. The method is validated according to International Conference on Harmonization guidelines and proven to be suitable for stability testing, content uniformity testing, and quality control of these compounds in pharmaceutical preparations. PMID:19222927

Shaikh, Saleem; Muneera, M S; Thusleem, O A; Tahir, Muhammad; Kondaguli, Anand V

2009-02-01

86

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

PubMed Central

Chemometrics-assisted UV spectrophotometric and RP-HPLC methods are presented for the simultaneous determination of tolperisone hydrochloride (TOL) and diclofenac sodium (DIC) from their combined pharmaceutical dosage form. Chemometric methods are based on principal component regression and partial least-square regression models. Two sets of standard mixtures, calibration sets, and validation sets were prepared. Both models were optimized to quantify each drug in the mixture using the information included in the UV absorption spectra of the appropriate solution in the range 241–290 nm with the intervals ? = 1 nm at 50 wavelengths. The optimized models were successfully applied to the simultaneous determination of these drugs in synthetic mixture and pharmaceutical formulation. In addition, an HPLC method was developed using a reversed-phase C18 column at ambient temperature with a mobile phase consisting of methanol:acetonitrile:water (60:30:10 v/v/v), pH-adjusted to 3.0, with UV detection at 275 nm. The methods were validated in terms of linearity, accuracy, precision, sensitivity, specificity, and robustness in the range of 3–30 ?g/mL for TOL and 1–10 ?g/mL for DIC. The robustness of the HPLC method was tested using an experimental design approach. The developed HPLC method, and the PCR and PLS models were used to determine the amount of TOL and DIC in tablets. The data obtained from the PCR and PLS models were not significantly different from those obtained from the HPLC method at 95% confidence limit. PMID:24482768

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

2013-01-01

87

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

PubMed

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

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

2013-12-01

88

Influence of variation in mobile phase pH and solute pK(a) with the change of organic modifier fraction on QSRRs of hydrophobicity and RP-HPLC retention of weakly acidic compounds.  

PubMed

The variation in mobile phase pH and ionizable solute dissociation constant (pK(a)) with the change of organic modifier fraction in hydroorganic mobile phase has seemingly been a troublesome problem in studies and applications of reversed phase high performance liquid chromatography (RP-HPLC). Most of the early studies regarding the RP-HPLC of acid-base compounds have to measure the actual pH of the mixed mobile phase rigorously, sometimes bringing difficulties in the practices of liquid chromatographic separation. In this paper, the effect of this variation on the apparent n-octanol/water partition coefficient (K(ow)?) and the related quantitative structure-retention relationship (QSRR) of logK(ow)? vs. logk(w), the logarithm of retention factor of analytes in neat aqueous mobile phases, was investigated for weakly acidic compounds. This QSRR is commonly used as a classical method for K(ow) measurement by RP-HPLC. The theoretical and experimental derivation revealed that the variation in mobile phase pH and solute pK(a) will not affect the QSRRs of acidic compounds. This conclusion is proved to be suitable for various types of ion-suppressors, i.e., strong acid (perchloric acid), weak acid (acetic acid) and buffer salt (potassium dihydrogen phosphate/phosphoric acid, PBS). The QSRRs of logK(ow)? vs. logk(w) were modeled by 11 substituted benzoic acids using different types of ion-suppressors in a binary methanol-water mobile phase to confirm our deduction. Although different types of ion-suppressor all can be used as mobile phase pH modifiers, the QSRR model obtained by using perchloric acid as the ion-suppressor was found to have the best result, and the slightly inferior QSRRs were obtained by using acetic acid or PBS as the ion-suppressor. PMID:23158292

Han, Shu-ying; Liang, Chao; Zou, Kuan; Qiao, Jun-qin; Lian, Hong-zhen; Ge, Xin

2012-11-15

89

A developed and validated stability-indicating reverse-phase high performance liquid chromatographic method for determination of cefdinir in the presence of its degradation products as per International Conference on Harmonization guidelines.  

PubMed

The present article deals with the development and validation of a stability-indicating, reverse-phase high performance liquid chromatographic (RP-HPLC) method, for the determination of cefdinir on a Waters RP Spherisorb C-18 column (250 mm × 4.6 mm, 5 ?m). A mobile phase consisting of water (pH adjusted to 3.0 with orthophosphoric acid) : acetonitrile : methanol 13:5:2 (v/v/v) was used. The flow rate was 1 mL min(-1). The separation was performed at room temperature. Detection was carried out at 286 nm, using a PDA detector. The developed method was statistically validated for the linearity, accuracy, specificity, Limit of Detection (LOD), and Limit of Quantitation (LOQ). The specificity of the method was ascertained by forced degradation studies, by acid and alkali degradation, oxidation, photolysis, and heat degradation. The degraded products were well-separated from the analyte, with significant differences in their retention time values. The Beer Law was obeyed over a concentration range of 0.05 - 15.00 ?g mL(-1) and the correlation coefficient was 0.999. PMID:23781424

Hamrapurkar, Purnima; Patil, Priti; Phale, Mitesh; Gandhi, Mital; Pawar, Sandeep

2011-01-01

90

Scintillation is an indicator of astrometric stability  

NASA Astrophysics Data System (ADS)

We examine the relationship between astrometric stability and astrophysical properties in flat-spectrum radio-loud quasars making up the celestial reference frame. We use position determinations from geodetic very long baseline interferometry measurements and develop a new metric for source position stability. We then compare this quantity to two measures of source compactness: structure index, which probes structure on milliarcsecond scales and the presence of interstellar scintillation associated with the quasar, which probes scales of tens of ?as. We find that persistent scintillators have greater position stability than episodic scintillators, which are in turn more stable than non-scintillators. Scintillators are also more likely to be compact on milliarcsecond scales, as measured by the structure index. Persistent scintillators are therefore excellent candidates for inclusion in any future realization of the celestial reference frame. A list of these sources is presented in Appendix A. We find that slow (characteristic time-scale >3 d) scintillators have more stable positions than rapid scintillators, suggesting that they are more compact. High-cadence, long-term monitoring is therefore required to identify other members of this population of compact, high brightness temperature quasars.

Schaap, R. G.; Shabala, S. S.; Ellingsen, S. P.; Titov, O. A.; Lovell, J. E. J.

2013-09-01

91

Simultaneous detection of tocopherols, carotenoids, and chlorophylls in vegetable oils by direct injection C 30 RP-HPLC with coulometric electrochemical array detection  

Microsoft Academic Search

Detection and quantification of tocopherols, carotenoids, and chlorophylls in vegetable oil have been used to aid their authentication.\\u000a Their importance in influencing the oxidative stability of vegetable oils and their possible health benefits have been shown\\u000a in numerous studies. Therefore, the need for a rapid and reliable analysis method has become increasingly important. This\\u000a study demonstrates the application of C30

Ni Luh Puspitasari-Nienaber; Mario G. Ferruzzi; Steven J. Schwartz

2002-01-01

92

Identification and quantification of soluble free, soluble conjugated, and insoluble bound phenolic acids in durum wheat (Triticum turgidum L. var. durum) and derived products by RP-HPLC on a semimicro separation scale.  

PubMed

A straightforward semimicro separation scale RP-HPLC method was developed for the identification and quantification of phenolic acids (PAs) occurring as soluble free, soluble conjugated, and insoluble bound compounds, which were independently extracted from wholemeal of durum wheat and from its derived products coarse bran, semolina, and dried pasta. A narrow bore column and a semimicro photodiode array detector (PDA) cell, in conjunction with a single quadrupole mass spectrometer, equipped with an electrospray ionization source (ESI-MS), were employed. The method was validated in terms of linearity of calibration graphs, limits of detection, limits of quantification, repeatability, and accuracy, which was evaluated by a recovery study. In each sample (wholemeal, coarse bran, semolina, and dried pasta), the total amounts of the three different forms of PAs were in the order bound > conjugated > free, with bound PAs accounting for 61.0-83.6% of the total PAs. Ferulic acid was the most abundant PA in both soluble free and insoluble bound forms, whereas sinapic acid predominated in the conjugated ones. The highest PA content, calculated as the sum of total PAs quantified in the three forms, was found in coarse bran, followed by wholemeal, semolina, and dried pasta. PMID:24175612

Nicoletti, Isabella; Martini, Daniela; De Rossi, Antonella; Taddei, Federica; D'Egidio, Maria Grazia; Corradini, Danilo

2013-12-01

93

Validation and application of RP-HPLC method for the quantification of metoclopramide hydrochloride in oral formulations prepared for IVIVC studies.  

PubMed

The objective of this study is to develop sensitive and cost effective reverse phase high performance liquid chromatographic method for the estimation of Metoclopramide Hydrochloride in oral solid dosage formulations. A reverse chromatographic method was used with the mobile phase of Acetonitrile, 20m M Potassium dihydrogen phosphate buffer solution (pH 3 adjusted with orthophosphoric acid) in the ratio of 40:60. The column used was Waters C18 3.9×300mm µBondapak (RP). The flow rate of the mobile phase was 2ml/minute. The detector was set at the wavelength of 275nm.This method showed good sensitivity. The linearity was also found to be excellent (?(2)=0.997) in the range of 5-75 ?g/ml. No interfering peaks were observed at the retention time of Metoclopramide Hydrochloride when both placebo and blank samples were injected (Retention time =1.93min). The parameters such as specificity, linearity, range, accuracy, precision, system suitability, solution stability, detection and quantification limits were evaluated to validate this method. This method can effectively be used for quantitative analysis of Metoclopramide hydrochloride tablet formulations because of its specificity, accuracy and convenience of use. PMID:22186321

Khan, Ahmad; Naqvi, Syed Baqir S; Shoaib, Muhammad Harris; Yousaf, Rabia Ismail; Khan, Jallat; Hanif, Muhammad; Madni, Asadullah

2012-01-01

94

Microwave-assisted extraction of herbacetin diglucoside from flax (Linum usitatissimum L.) seed cakes and its quantification using an RP-HPLC-UV system.  

PubMed

Flax (Linum usitatissimum L.) seeds are widely used for oil extraction and the cold-pressed flaxseed (or linseed) cakes obtained during this process constitute a valuable by-product. The flavonol herbacetin diglucoside (HDG) has been previously reported as a constituent of the flaxseed lignan macromolecule linked through ester bonds to the linker molecule hydroxymethylglutaric acid. In this context, the development and validation of a new approach using microwave-assisted extraction (MAE) of HDG from flaxseed cakes followed by quantification with a reverse-phase HPLC system with UV detection was purposed. The experimental parameters affecting the HDG extraction yield, such as microwave power, extraction time and sodium hydroxide concentration, from the lignan macromolecule were optimized. A maximum HDG concentration of 5.76 mg/g DW in flaxseed cakes was measured following an irradiation time of 6 min, for a microwave power of 150 W using a direct extraction in 0.1 M NaOH in 70% (v/v) aqueous methanol. The optimized method was proven to be rapid and reliable in terms of precision, repeatability, stability and accuracy for the extraction of HDG. Comparison with a conventional extraction method demonstrated that MAE is more effective and less time-consuming. PMID:24619301

Fliniaux, Ophélie; Corbin, Cyrielle; Ramsay, Aina; Renouard, Sullivan; Beejmohun, Vickram; Doussot, Joël; Falguières, Annie; Ferroud, Clotilde; Lamblin, Frédéric; Lainé, Eric; Roscher, Albrecht; Grand, Eric; Mesnard, François; Hano, Christophe

2014-01-01

95

Simultaneous determination of phenolic acids and flavonoids in rice using solid-phase extraction and RP-HPLC with photodiode array detection.  

PubMed

An analytical method based on an optimized solid-phase extraction procedure and followed by high-performance liquid chromatography (HPLC) separation with diode array detection was developed and validated for the simultaneous determination of phenolic acids (gallic, protocatechuic, 4-hydroxy-benzoic, vanillic, caffeic, syringic, p-coumaric, ferulic, sinapic, and cinnamic acids), flavanols (catechin and epicatechin), flavonols (myricetin, quercetin, kaempferol, quercetin-3-O-glucoside, hyperoside, and rutin), flavones (luteolin and apigenin) and flavanones (naringenin and hesperidin) in rice flour (Oryza sativa L.). Chromatographic separation was carried out on a PerfectSil Target ODS-3 (250 mm × 4.6 mm, 3 ?m) column at temperature 25°C using a mobile phase, consisting of 0.5% (v/v) acetic acid in water, methanol, and acetonitrile at a flow rate 1 mL min(-1) , under gradient elution conditions. Application of optimum extraction conditions, elaborated on both Lichrolut C(18) and Oasis HLB cartridges, have led to extraction of phenolic acids and flavonoids from rice flour with mean recoveries 84.3-113.0%. The developed method was validated in terms of linearity, accuracy, precision, stability, and sensitivity. Repeatability (n = 5) and inter-day precision (n = 4) revealed relative standard deviation (RSD) <13%. The optimized method was successfully applied to the analysis of phenolic acids and flavonoids in pigmented (red and black rice) and non-pigmented rice (brown rice) samples. PMID:22761138

Irakli, Maria N; Samanidou, Victoria F; Biliaderis, Costas G; Papadoyannis, Ioannis N

2012-07-01

96

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

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

Khan, Abbas; Iqbal, Zafar; Khan, Muhammad Imran; Javed, Khalid; Khan, Abad; Ahmad, Lateef; Shah, Yasar; Nasir, Fazli

2011-08-15

97

Rapid determination of total solanesol in tobacco leaf by ultrasound-assisted extraction with RP-HPLC and ESI-TOF/MS.  

PubMed

A reliable and rapid method based on high-performance liquid chromatography (HPLC-UV) and positive ion electrospray-time of flight mass spectrometry (ESI-TOF/MS) has been developed for the characterization and quantification of solanesol in extracts of tobacco leaves from different sources. The solanesol was extracted from tobacco leaf via saponification and ultrasonic-assist extraction, and the extraction conditions were optimized. The HPLC conditions are as following: Hypersil C(4) (4.6 mm x 150 mm, 5 microm) column, acetonitrile and water as mobile phase, flow-rate is 0.8 ml/min, detection length of UV is 202 nm, injection volume is 10 microl. The results indicated that the developed HPLC method is simple, sensitive and reliable for the determination of solanesol in tobacco leaves with a linear dynamic range of 3.65-4672 ng, a detection limit of 1.83 ng, and an average recovery of 98.7%. The method has been applied to analyze and compare different tobacco samples. The results show that the solanesol content in samples of different geographic locations varies widely from 0.20 to 1.50%. When different parts of the tobacco plant are compared, the top parts of the leaves are more abundant in solanesol content than those of lower parts. PMID:17029669

Chen, Junhui; Liu, Xianping; Xu, Xiaoqin; Lee, Frank Sen-Chun; Wang, Xiaoru

2007-02-19

98

Quantitative and Chemical Fingerprint Analysis for the Quality Evaluation of Receptaculum Nelumbinis by RP-HPLC Coupled with Hierarchical Clustering Analysis.  

PubMed

A simple and reliable method of high-performance liquid chromatography with photodiode array detection (HPLC-DAD) was developed to evaluate the quality of Receptaculum Nelumbinis (dried receptacle of Nelumbo nucifera) through establishing chromatographic fingerprint and simultaneous determination of five flavonol glycosides, including hyperoside, isoquercitrin, quercetin-3-O-?-d-glucuronide, isorhamnetin-3-O-?-d-galactoside and syringetin-3-O-?-d-glucoside. In quantitative analysis, the five components showed good regression (R > 0.9998) within linear ranges, and their recoveries were in the range of 98.31%-100.32%. In the chromatographic fingerprint, twelve peaks were selected as the characteristic peaks to assess the similarities of different samples collected from different origins in China according to the State Food and Drug Administration (SFDA) requirements. Furthermore, hierarchical cluster analysis (HCA) was also applied to evaluate the variation of chemical components among different sources of Receptaculum Nelumbinis in China. This study indicated that the combination of quantitative and chromatographic fingerprint analysis can be readily utilized as a quality control method for Receptaculum Nelumbinis and its related traditional Chinese medicinal preparations. PMID:23337200

Wu, Yan-Bin; Zheng, Li-Jun; Yi, Jun; Wu, Jian-Guo; Chen, Ti-Qiang; Wu, Jin-Zhong

2013-01-01

99

Quantitative and Chemical Fingerprint Analysis for the Quality Evaluation of Receptaculum Nelumbinis by RP-HPLC Coupled with Hierarchical Clustering Analysis  

PubMed Central

A simple and reliable method of high-performance liquid chromatography with photodiode array detection (HPLC-DAD) was developed to evaluate the quality of Receptaculum Nelumbinis (dried receptacle of Nelumbo nucifera) through establishing chromatographic fingerprint and simultaneous determination of five flavonol glycosides, including hyperoside, isoquercitrin, quercetin-3-O-?-d-glucuronide, isorhamnetin-3-O-?-d-galactoside and syringetin-3-O-?-d-glucoside. In quantitative analysis, the five components showed good regression (R > 0.9998) within linear ranges, and their recoveries were in the range of 98.31%–100.32%. In the chromatographic fingerprint, twelve peaks were selected as the characteristic peaks to assess the similarities of different samples collected from different origins in China according to the State Food and Drug Administration (SFDA) requirements. Furthermore, hierarchical cluster analysis (HCA) was also applied to evaluate the variation of chemical components among different sources of Receptaculum Nelumbinis in China. This study indicated that the combination of quantitative and chromatographic fingerprint analysis can be readily utilized as a quality control method for Receptaculum Nelumbinis and its related traditional Chinese medicinal preparations. PMID:23337200

Wu, Yan-Bin; Zheng, Li-Jun; Yi, Jun; Wu, Jian-Guo; Chen, Ti-Qiang; Wu, Jin-Zhong

2013-01-01

100

Simultaneous determination of ascorbic acid, aminothiols, and methionine in biological matrices using ion-pairing RP-HPLC coupled with electrochemical detector.  

PubMed

A novel highly sensitive ion-pairing reversed-phase high performance liquid-chromatography/electrochemical detection method for simultaneous determination of l-ascorbic acid, aminothiols, and methionine in biological matrices was developed, optimized, and validated. Reduced forms of the analytes were extracted from the sample matrices with 10% meta-phosphoric acid solution((aqueous)). To determine the total vitamin C, the total aminothiols, and the total methionine, samples were treated with tris(2-carboxyethyl)phosphine solution in 0.05% trifluoroacetic acid solution((aqueous)) subsequent to deproteination to reduce the oxidized forms of these compounds. Various analytes were separated on a C(18) (250 × 4.6 mm, 5 ?m) analytical column using methanol-0.05% trifluoroacetic acid solution((aqueous)) (05/95, v/v), containing 0.1mM 1-octane sulphonic acid as the ion-pairing agent) as the isocratic mobile phase pumped at a flow rate of 1.5 mL min(-1) at room temperature. The column eluents were monitored at a voltage of 0.85 V. These analytes were efficiently resolved in less than 20 min using n-acetyl cysteine as the internal standard. The present method was specific for the analysis of these analytes and demonstrated acceptable values for linearity (r(2)>0.999 in the range of 0.2-10,000 ng mL(-1) for all the analytes), recovery (>96%), precision (%RSD ? 2.0), and sensitivity (on column limit of detection: 250-400 fg and limit of quantification: 0.8-1.25 pg), indicating that the proposed method could be efficiently used for determination of these analytes in the context of clinical research. PMID:21820976

Khan, Muhammad Imran; Iqbal, Zafar

2011-09-01

101

Stability Indicating Assay of Lidocaine Hydrochloride in Solution  

Microsoft Academic Search

A simple and improved stability-indicating gas liquid chromatographic procedure using flame ionization detection is described for the determination of lidocaine hydrochloride in solution in the presence of N, N'-diethyl-methyl-glycine xylidide as internal standard (IST). This method is capable of distinguishing the intact drug from its thermal degradation products. A linear relationship between peak height ratio (lidocaine-HC1\\/IST) and lidocaine-HCl concentrations is

S. Stavchansky; B. Eghbali; R. Geary

1987-01-01

102

Stability Indices derived from Atmospheric Measurements on a Cable Car  

NASA Astrophysics Data System (ADS)

Stability indices are meteorological parameters to describe vertical atmospheric layering and therefore it is possible to predict convective events such as thunderstorms. Commonly, weather balloons with radiosondes are used for the analysis of vertical atmospheric layering. These weather balloons reach high altitudes and atmospheric layering can be determined for the entire troposphere. On the other hand, these balloon ascents are expensive, require the appropriate equipment and permissions and cannot be conducted several times a day on an operational basis. Due to the limitations of the application of weather balloons the unconventional idea came up to equip a cable car with meteorological instruments for vertical profile measurements. To some extent the meteorological instruments had to be customized to the particular requirements and data are transmitted via GSM. The investigated area is a small alpine catchment which is prone to flash floods and thus a reliable forecast for such floods mostly caused by convective rainfall events is important. Therefore the purpose of this contribution is to proof if a cable car can be used for measuring continuous data during the operating hours and whether it is possible to derive reliable conclusions about the stability in the lower troposphere. Several stability indices (e.g. Lifted-, Showalter-, Boyden- and Convective-Index) were investigated. Indices which are calculated on the basis of the "Lifted Parcel Theory" were tested with different approaches to determine the most unstable parcel and therefore the initial values of the required parameters. The derived indices were flagged in active (thunderstorms) and non-active (no thunderstorms) cases. The classification results from available lightning maps in this region. Threshold values were established to distinguish stable, potential indifferent and unstable atmospheric conditions. On the basis of this division pre-warnings for the occurrence of thunderstorms are declared. The verification of the quality of these predictions is done by a skill score statistic.

Herma, F.; Seidel, J.; Bárdossy, A.

2012-04-01

103

Evaluation of time stability indices for soil water storage upscaling  

NASA Astrophysics Data System (ADS)

SummaryTime stability index (TSI) is usually used to evaluate time stability of soil water storage (SWS) at point scales for SWS upscaling. The objective of this study was to evaluate seven TSIs for estimating mean SWS. Included were six indices used for indirect estimation (i.e., standard deviation of relative difference (SDRD), mean absolute bias error (MABE), width of the 90% empirical tolerance interval of relative water content (T), chi-squared statistic (?2), root-mean-squared differences (D), and temporal coefficient of variability (CVt)); and one index used for direct estimation (i.e., root mean square error (RMSE)). Five goodness-of-fit indices (GFIs), including root mean squared deviations (RMSD), Nash-Sutcliffe coefficient of efficiency (NSCE), coefficient of determination (R2), absolute mean difference (BIAS), and relative bias error (RBIAS) were selected for evaluating mean SWS estimation quality in both calibration and validation periods. The minimum number of sampling occasions needed to identify the most time-stable location was identified considering different starting dates of sampling. Evaluation of the TSIs was performed using SWS data of 0-1.0 m layer obtaining from the Canadian Prairie landscape and the Chinese Loess Plateau. The results showed that MABE, ?2, D, and CVt outperformed SDRD and T irrespective of the GFI used. If RMSD and NSCE were used, D was the best TSI. If BIAS and RBIAS were adopted, MABE was the best TSI. Mean SWS estimation by the indirect method was more accurate than that by the direct method. For both study areas, the minimum number of sampling occasions needed to identify the most time-stable location varied with starting dates of SWS measurement, and generally five to seven sampling occasions was needed to identify the most time-stable location with D and MABE.

Hu, Wei; Tallon, Lindsay K.; Si, Bing Cheng

2012-12-01

104

A Stability Indicating Capillary Electrophoresis Method for Analysis of Buserelin  

PubMed Central

A simple and rapid stability indicating method based on capillary zone electrophoresis has been developed and validated for the analysis of buserelin (BUS). The best separations were achieved by using a bare fused silica capillary (75 ?m i.d.; 65.5 cm total, 57.0 cm effective length), phosphate buffer (pH = 3.00; 26.4 mM), at 35 °C. The sample was hydrodynamically injected at 50 mbar for 5 seconds; the applied voltage was 30 kV and detection was carried out by UV-absorbance at 200 nm. Method validation resulted in the following figures of merit : the method was linear in the concentration range between 0.781 and 500 ?g/mL (linear regression coefficient 0.9996), accuracy was between 99.3% and 100.9%, intra assay precision was between 0.3% and 1.0% and intermediate precision was between 1.0% and 2.1%. Evaluation of the specificity of the method showed no interference between excipients or products of force degradation and BUS. Under the selected conditions, separation of BUS and its degradation products was completed in less than 10 min, and BUS could be quantified after different stress conditions without any interference. The results enabled the conclusion that under thermal stress upon exposure to 90 °C BUS is degraded by first order kinetics. It was demonstrated that the method can be applied as a rapid and easy to use method for quantification and stability testing of BUS in biopharmaceutical formulations in quality control laboratories.

Tamizi, Elnaz; Kenndler, Ernst; Jouyban, Abolghasem

2014-01-01

105

Stability-Indicating HPLC Method for Posaconazole Bulk Assay  

PubMed Central

A stability-indicating liquid chromatographic (LC) method was developed for the determination of posaconazole in bulk. Chromatographic separation was achieved using an isocratic elution in a reversed-phase system, with a mobile phase composed of methanol-water (75:25, v/v), at 1.0 mL min?1 flow. Samples were exposed to degradation under thermal, oxidative and acid/basic conditions, and no interference in the analysis was observed. System suitability was evaluated and results were satisfactory (N = 4,900.00 tailing factor 1.04; RSD between injections = 0.65). The retention time of posaconazole was about 8.5 min and the method was validated within the concentration range 5–60 ?g mL?1 (r = 0.9996). Adequate results were obtained for repeatability (RSD % = 0.86–1.22), inter-day precision (RSD % = 1.21) and accuracy (98.13% mean recovery). Robustness was also determined to be satisfactory after evaluation. The proposed method was successfully applied to posaconazole bulk quantification, showing the method is useful for determination of the drug in routine analysis. PMID:22896819

Garcia, Cassia V.; Costa, Gislaine R.; Mendez, Andreas S. L.

2012-01-01

106

Herring gull eggs indicate stabilizing Great Lakes PCB concentrations  

SciTech Connect

The author evaluated the fit of 3 alternative models to herring gull (Larus argentatus) egg PCB concentration data from 1978--1992 to examine whether PCB levels were decreasing or had ceased to decline. The best fit models indicate that, following initial declines, no discernible PCB decreases are occurring in 4 of the 5 lakes. Only Lake Erie indicates a continued PCB decline, though the Erie data may be too noisy to differentiate model fits. These results are consistent with previous analyses indicating stable PCB concentrations in Lake Michigan fishes and suggest that further improvements may be too slow to be of practical importance from a management perspective.

Stow, C. [Univ. of Wisconsin, Madison, WI (United States). Center for Limnology

1995-12-31

107

Solution stability of salmon calcitonin at high concentration for delivery in an implantable system.  

PubMed

Salmon calcitonin solutions (50 mg/mL and 100 mg/mL) were placed on stability at 37 degrees C for 1 year in a variety of solvent systems including water, ethanol, glycerol, propylene glycol (PG) and dimethyl sulfoxide (DMSO). Calcitonin degradation was monitored by RP-HPLC and size-exclusion chromatography. DMSO and pH 3.3 solutions provided optimum stability. Conformational stability was also monitored by FTIR over the 1 year time course and compared with chemical and physical stability. After 12 months at 37 degrees C, four major conformations were observed: a beta-sheet conformation (pH 3.3, pH 5.0, 70% DMSO and 70% glycerol), an aggregate conformation (pH 7.0 water), a strong alpha-helical conformation (70% EtOH, 70% PG) and a weak alpha-helical conformation (100% DMSO). No correlation between structure and chemical stability was observed in which both the beta-sheet structure (pH 3.3, water) and a loose alpha-helical structure (100% DMSO) demonstrated good stability. However, some correlation was observed between structure and physical stability, where co-solvents inducing an alpha-helical structure resulted in a decrease in gelation. These two structural states associated with improved stability and minimal gelation, indicated that gelation can be reduced or eliminated by the use of pharmaceutically acceptable co-solvents. Finally, salmon calcitonin (50 mg/mL) was formulated in 100% DMSO and delivered from a DUROS implant over 4 months. Delivery at a target dose of 18 microg/day calcitonin at 37 degrees C was confirmed. PMID:10784029

Stevenson, C L; Tan, M M

2000-02-01

108

Stability and Variability: Indicators for Passive Stability and Active Control in a Rhythmic Task  

E-print Network

was varied and showed that actors graded these three components as a function of task stability It is widely recognized that stability is a core requirement for many motor tasks. Despite external. 2003), to voluntary intervention on the basis of perceptual information (Hasan 2005; Loram and Lakie

Sternad, Dagmar

109

Assessment of the Stability of Novel Antibacterial Triazolyl Oxazolidinones Using a Stability-Indicating High-Performance Liquid Chromatography Method  

Microsoft Academic Search

Objectives: To evaluate the stability of 12 triazolyl oxazolidinone (TOZ) derivatives in simulated gastric and intestinal fluids as well as in human plasma at 37 ± 1°C. Materials and Methods: A stability-indicating high-performance liquid chromatography (HPLC) procedure with a C8 column (250 × 40 mm, 5 ?m particle size) and a mobile phase of acetonitrile\\/H2O (50\\/50 v\\/v) at 1.0 ml\\/min

Oludotun A. Phillips; Leyla H. Sharaf; Mohammed E. Abdel-Hamid; Reny Varghese

2011-01-01

110

RP-HPLC Estimation of Ramipril and Telmisartan in Tablets  

PubMed Central

A rapid high performance liquid chromatographic method has been developed and validated for the estimation of ramipril and telmisartan simultaneously in combined dosage form. A Genesis C18 column having dimensions of 4.6×250 mm and particle size of 5 ?m in isocratic mode, with mobile phase containing a mixture of 0.01 M potassium dihydrogen phosphate buffer (adjusted to pH 3.4 using orthophosphoric acid): methanol:acetonitrile (15:15:70 v/v/v) was used. The mobile phase was pumped at a flow rate of 1.0 ml/min and the eluents were monitored at 210 nm. The selected chromatographic conditions were found to effectively separate ramipril (Rt: 3.68 min) and telmisartan (Rt: 4.98 min) having a resolution of 3.84. The method was validated in terms of linearity, accuracy, precision, specificity, limit of detection and limit of quantitation. Linearity for ramipril and telmisartan were found in the range of 3.5-6.5 ?g/ml and 28.0-52.0 ?g/ml, respectively. The percentage recoveries for ramipril and telmisartan ranged from 99.09-101.64% and 99.45-100.99%, respectively. The limit of detection and the limit of quantitation for ramipril was found to be 0.5 ?g/ml and 1.5 ?g/ml respectively and for telmisartan was found to be 1.5 ?g/ml and 3.0 ?g/ml, respectively. The method was found to be robust and can be successfully used to determine the drug content of marketed formulations. PMID:20336215

Kurade, V. P.; Pai, M. G.; Gude, R.

2009-01-01

111

Characterization, thermal stability studies, and analytical method development of Paromomycin for formulation development.  

PubMed

Paromomycin (PM) is an aminoglycoside antibiotic, first isolated in the 1950s, and approved in 2006 for treatment of visceral leishmaniasis. Although isolated six decades back, sufficient information essential for development of pharmaceutical formulation is not available for PM. The purpose of this paper was to determine thermal stability and development of new analytical method for formulation development of PM. PM was characterized by thermoanalytical (DSC, TGA, and HSM) and by spectroscopic (FTIR) techniques and these techniques were used to establish thermal stability of PM after heating PM at 100, 110, 120, and 130 °C for 24 h. Biological activity of these heated samples was also determined by microbiological assay. Subsequently, a simple, rapid and sensitive RP-HPLC method for quantitative determination of PM was developed using pre-column derivatization with 9-fluorenylmethyl chloroformate. The developed method was applied to estimate PM quantitatively in two parenteral dosage forms. PM was successfully characterized by various stated techniques. These techniques indicated stability of PM for heating up to 120 °C for 24 h, but when heated at 130 °C, PM is liable to degradation. This degradation is also observed in microbiological assay where PM lost ?30% of its biological activity when heated at 130 °C for 24 h. New analytical method was developed for PM in the concentration range of 25-200 ng/ml with intra-day and inter-day variability of < 2%RSD. Characterization techniques were established and stability of PM was determined successfully. Developed analytical method was found sensitive, accurate, and precise for quantification of PM. Copyright © 2010 John Wiley & Sons, Ltd. PMID:21698779

Khan, Wahid; Kumar, Neeraj

2011-06-01

112

Two Approaches to Examining the Stability of Myers-Briggs Type Indicator Scores  

ERIC Educational Resources Information Center

In this study, two approaches are used to assess the stability of Myers-Briggs Type Indicator scores across 3 administrations (N = 231): longitudinal configural frequency analysis with categorical scores and generalizability theory with the Preference Clarity Indices and continuous scores. The results are generally positive. Evaluation of…

Salter, Daniel W.; Forney, Deanna S.; Evans, Nancy J.

2005-01-01

113

The Effect of Ankle Taping and Balance Exercises on Postural Stability Indices in Healthy Women  

PubMed Central

[Purpose] The purpose of this study was to compare the effect of ankle taping and balance exercises on postural stability indices in healthy women. [Subjects and Methods] Thirty healthy female students were randomly assigned into two equal groups: ankle taping and balance exercise. The balance exercise group performed balance exercises for 6 weeks, with 3 sessions per week and each session lasting 40 minutes. Ankle joint taping was performed for 6 weeks and was renewed three times a week. Before and after the interventions, overall, anteroposterior, and mediolateral stability indices were measured with a Biodex Balance System in bilateral and unilateral stance positions with the eyes open and closed. [Results] In the taping group during bilateral standing with the eyes closed, the overall stability index changed from 6±1.4 to 4.8±1.3, anteroposterior stability index changed from 4.2±1.27 to 3.4±0.97, and mediolateral stability index changed from 3.2±0.75 to 2.7± 0.7. In the balance exercise group during bilateral standing with the eyes closed, the overall stability index changed from 5.7±1.69 to 4.5±1.94, anteroposterior stability index changed from 4.1±1.61 to 3±1.21, and mediolateral stability index changed from 3.5±1.4 to 2.2± 1.3. No significant difference was seen between the two groups regarding any study variables. [Conclusion] The results showed that compared with the taping technique, balance training increases postural stability in the majority of the studied balance situations. PMID:24926148

Akbari, Asghar; Sarmadi, Alireza; Zafardanesh, Parisa

2014-01-01

114

Stability indicating HPTLC method for the simultaneous determination of pseudoephedrine and cetirizine in pharmaceutical formulations  

Microsoft Academic Search

The combination of pseudoephedrine and cetirizine is widely used in the treatment of allergic rhinitis. A rapid, selective and stability indicating high performance thin layer chromatographic method was developed and validated for their simultaneous estimation in pharmaceutical dosage forms. The method employed TLC aluminium plates precoated with silica gel 60F-254 as the stationary phase. The solvent system consisted of ethyl

Sapna N Makhija; Pradeep R Vavia

2001-01-01

115

Stress degradation studies on ezetimibe and development of a validated stability-indicating HPLC assay  

Microsoft Academic Search

Ezetimibe was subjected to different ICH prescribed stress conditions. Degradation was found to occur in hydrolytic and to some extent in photolytic conditions, while the drug was stable to oxidative and thermal stress. The drug was particularly labile under neutral and alkaline hydrolytic conditions. A stability-indicating HPLC method was developed for analysis of the drug in the presence of the

Saranjit Singh; Baljinder Singh; Rakesh Bahuguna; Lalit Wadhwa; Rahul Saxena

2006-01-01

116

STABILITY INDICATING ASSAY AND KINETIC STUDY FOR NORFLOXACIN USING TLC-DENSITOMETRIC METHOD  

Microsoft Academic Search

A new, simple and stability indicating thin layer chromatographic (TLC) method has been developed for estimation of norfloxacin. Study was performed on pre-coated silica gel F254 TLC plate using environmentally safe mobile phase consisting of n-butanol: methanol: ammonia (33%) (8:1:3.5 v\\/v). A Camag TLC Scanner 3 set at 282 nm was used for direct determination of the chromatograms in the reflectance\\/absorbance mode.

Gamal A. Saleh; Hassan F. Askal; Ibrahim H. Refaat; Fatma A. M. Abdel-aal

2012-01-01

117

A validated stability-indicating HPLC method for determination of varenicline in its bulk and tablets  

Microsoft Academic Search

A simple, sensitive and accurate stability-indicating HPLC method has been developed and validated for determination of varenicline\\u000a (VRC) in its bulk form and pharmaceutical tablets. Chromatographic separation was achieved on a Zorbax Eclipse XDB-C8 column\\u000a (150 mm × 4.6 mm i.d., particle size 5 ?m, maintained at ambient temperature) by a mobile phase consisted of acetonitrile\\u000a and 50 mM potassium

Adnan A Kadi; Mostafa S Mohamed; Mohamed G Kassem; Ibrahim A Darwish

2011-01-01

118

Evaluation of degradation kinetics for abamectin in formulations using a stability indicating method.  

PubMed

The aim of this study was to evaluate stability characteristics and kinetics behavior of abamectin (ABM) as a 1 % (m/V) topical veterinary solution. During the study, samples stressed at 55 and 70 °C were regularly analyzed for several parameters over 8 weeks on a chromatographic (HPLC) system, using a Prodigy C18, 250 x 4.6 mm, 5-?m, column eluting with 15 : 34 : 51 (V/V/V) water/methanol/ acetonitrile as mobile phase. The HPLC method was validated for precision, accuracy, linearity and specificity, and was found to be stability indicating. The results showed that degradation of ABM followed first-order kinetics and data on loss in kobs (s-1) and half life (t1/2, days) demonstrated ABM showing the maximum stability in glycerol formal. The degradation behavior of ABM varies from solvent to solvent. The effect of added alkali on pH change and loss of ABM was studied and found to be unique for all solvents and very distinct from typical hydrolysis degradation. The present study may serve as a platform to design and develop topical non-aqueous solutions of ABM for veterinary use given no such comprehensive efforts have been published to date on the stability profile of ABM in non-aqueous solvents. PMID:23482313

Awasthi, Atul; Razzak, Majid; Al-Kassas, Raida; Harvey, Joanne; Garg, Sanjay

2013-03-01

119

STABILITY-INDICATING MICELLAR ELEKTROKINETIC CHROMATOGRAPHY METHOD FOR DETERMINATION OF FINASTERIDE IN PHARMACEUTICAL PREPARATIONS  

Microsoft Academic Search

A stability-indicating micellar electrokinetic chromatography method has been developed and validated for determination of finasteride. Analysis was performed by using 50 cm × 100 µm i.d. (effective length 42.8 cm) fused silica capillary and background electrolyte of 50 mM NaH2PO4 (pH 3) buffer containing 10 mM sodium dodecyl sulfate as surfactant. Applied potential was selected as ? 15 kV at 25°C and the detection was at 210 nm. The calibration curve

Mehmet Gokhan Caglayan; Ismail Murat Palabiyik; Feyyaz Onur

2012-01-01

120

Simultaneous Determination of Losartan Potassium, Atenolol and Hydrochlorothiazide in Pharmaceutical Preparations by Stability-Indicating UPLC  

Microsoft Academic Search

A stability-indicating UPLC method was developed for the simultaneous quantitative determination of losartan potassium, atenolol,\\u000a and hydrochlorothiazide in pharmaceutical dosage forms in the presence of degradation products. The separation was achieved\\u000a on a simple isocratic method (water: acetonitrile: triethyl amine: ortho phosphoric acid (60:40:0.1:0.1, v\\/v) at 0.7 mL min?1, a detection wavelength of 225 nm). The retention times of losartan potassium, atenolol, and

D. Durga Rao; N. V. Satyanarayana; S. S. Sait; Y. Ramakoti Reddy; K. Mukkanti

2009-01-01

121

Performance Comparison of Voltage Stability Indices for Weak Bus Identification in Power Systems  

NASA Astrophysics Data System (ADS)

Voltage collapse event is identified as complex and localized in nature but its effect is extensive once occurred. The vital effect of voltage collapse would be the total system collapse or blackouts which would cost a large loss to utility companies. Eventually, on- line monitoring of power system stability has become an important factor for electric power utilities. The last utmost option to avert voltage collapse incident from occurring is by the implementation of under voltage load shedding scheme. The identification of location for load shedding is the main motivation of the study. The weakest bus in a power system is identified as the location for load shedding. This location is obtained using voltage stability index Ld. The performance and effectiveness of Ld index is compared with Fast Voltage Stability Index (FVSI) and Le Index. The results obtained indicate that Ld Index can be used to identify the weak bus in a power system and consequently for the placement of UVLS relays in a power system network.

Verayiah, R.; Mohamed, A.; Shareef, H.; Zainal Abidin, I. Hj

2013-06-01

122

Development and validation of a stability-indicating high performance liquid chromatographic assay for benoxinate.  

PubMed

Benoxinate is a local anaesthetic used for ophthalmic applications. The aim of this study was to develop a rapid and simple stability-indicating method for the determination of benoxinate formulated for ophthalmic use, evaluate its long-term stability and identify its major degradation product. Benoxinate was eluted on a 10 microm Spherisorb phenyl column, 250 x 3.2 mm, with a mobile phase consisting of acetonitrile-buffer (pH 3.5) (35:65, v/v), pumped at 0.8 ml min(-1) flow rate. The buffer was composed of sodium dihydrogen phosphate (50 mM), sodium hydrogen sulfate (2.5 mM) and 1-heptanesulfonic acid sodium salt (5 mM). The analyte was quantified spectrophotometrically at 308 nm. The chromatograms of benoxinate formulations obtained by this method showed benoxinate (t = 4.5 min) well resolved from its degradation product (t = 2.3 min), which was separately identified by means of HPLC-MS as 4-amino-3-butoxybenzoic acid. The assay was demonstrated to have high accuracy, precision and linearity. The method was implemented in investigating the long-term stability of benoxinate 0.4% ophthalmic solutions. The method was found to be simple, quick and selective in determining benoxinate concentrations in fresh and aged preparations. PMID:12852462

Chorny, Michael; Levy, Daniel; Schumacher, Ilana; Lichaa, Chaim; Gruzman, Boris; Livshits, Oleg; Lomnicky, Yossi

2003-04-24

123

Determination of fesoterodine in a pharmaceutical preparation by a stability-indicating capillary zone electrophoresis method.  

PubMed

A simple, stability-indicating capillary zone electrophoresis (CZE) method was developed and validated for the analysis of fesoterodine (FESO) in tablets. Optimal conditions for the separation of FESO and its degradation products were investigated. The method used 10 mM sodium phosphate buffer at pH 6.5 as the background electrolyte with an applied voltage of 30 kV (positive polarity).The capillary length was 80.5 cm (72 cm to the detector), and the detection wavelength was 208 nm. The method was validated in accordance with the International Conference on Harmonization requirements, which involved specificity, linearity, precision, accuracy, robustness, LOD, and LOQ. The stability-indicating capability of the method was established by stress degradation studies combined with peak purity assessment using photodiode array detection. The method was linear over the concentration range of 2-100 microg/mL (r2 = 0.9998) of FESO. Intraday and interday precision and accuracy evaluated by RSD, respectively, were all lower than 2%. The LOD and LOQ were 0.57 and 1.90 microg/mL, respectively. The method proved to be robust by a fractional factorial design evaluation. The proposed CZE method was successfully applied for the quantitative analysis of FESO in extended-release tablets to support its QC. PMID:24645509

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

2013-01-01

124

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

PubMed

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

Liew, Kai Bin; Peh, Kok Khiang

2014-01-01

125

Influence of alkyl chain length on the stability of n-alkyl-modified reversed phases. 1. Chromatographic and physical analysis  

SciTech Connect

The influence of the ligand alkyl chain length, chemically bonded at the surface of a silica substrate, on stationary phase stability in liquid chromatography practice is reviewed. Several factors affecting long-term stability of modern reversed-phase high-performance liquid chromatography (RP-HPLC) phases are considered and their individual contributions are evaluated in this paper. The stationary phases under study were identically modified on the same batch of silica substrate to eliminate differences in substrate properties and synthesis conditions. Modifications with ligand alkyl chain length between C{sub 1} and C{sub 18} were performed such that an approximately equal ligand density was obtained for the seven RP-HPLC phases studied. These n-alkyldimethylsiloxysilane bonded phases were exposed to simulated aging experiments. A subsequent chromatographic characterization regarding changes in capacity, lipophilic and polar selectivity, and silica degradation related separation performance was carried out. Comparison with results determined by other characterization methods, like bulk analysis, elemental analysis, and solid-state {sup 29}Si cross-polarization magic angle spinning NMR revealed that with longer n-alkyl ligands gradually better substrate shielding properties were obtained.

Hetem, M.J.J.; de Haan, J.W.; Claessens, H.A.; van de Ven, L.J.M.; Cramers, C.A. (Eindhoven Univ. of Technology (Netherlands)); Kinkel, J.N. (E. Merck, Darmstadt (West Germany))

1990-11-01

126

Spectrophotometric and stability-indicating high-performance liquid chromatographic determinations of terbutaline sulfate.  

PubMed

Spectrophotometric and stability-indicating HPLC procedures are described for determination of terbutaline sulfate in bulk powder and dosage form. The first procedure is based on diazo coupling of the phenolic groups of terbutaline sulfate with fast red B salt in the presence of sodium hydroxide. The colored compound developed in alkaline medium was measured at 475 nm. Different variables affecting the reaction were studied. Beer's Law is obeyed in the concentration range of 1-6 microg/mL. In the HPLC procedure, the separation was carried out on a Caltrex AIII column, a relatively new packing material consisting of silica-bonded calix[8]arene, using an isocratic binary mobile phase, acetonitrile-ammonium acetate (50 + 50, v/v), at pH 6.2. A diode array detector was used at 280 nm. The method was validated for system suitability, linearity, precision, LOD, LOQ, specificity, stability, and robustness. The LOD and LOQ were 0.196 and 0.781 microg/mL, respectively. The recovery values of this method were between 98 and 102%, and the reproducibility was within 0.92%. Statistical comparison of the results obtained from the analysis of the studied drug to those of the official British Pharmacopoeia (2007) method using t- and F-tests showed no significant difference between them. PMID:23175974

Hashem, Hisham A; Elmasry, Manal S; Hassan, Wafaa E; Tründelberg, Clemens; Jira, Thomas

2012-01-01

127

Stability-indicating study of the anti-Alzheimer's drug galantamine hydrobromide.  

PubMed

Galantamine hydrobromide was subjected to different stress conditions (acidic, alkaline, thermal, photolytic and oxidative). Degradation was found to occur under acidic, photolytic and oxidative conditions, while the drug was stable under alkaline and elevated temperature conditions. A stability-indicating reversed-phase liquid chromatographic method was developed for the determination of the drug in the presence of its degradation products. The method was validated for linearity, precision, accuracy, specificity, selectivity and intermediate precision. Additionally, the degradation kinetics of the drug was assessed in relevant cases. The kinetics followed a first order behavior in the case of acidic and photolytic degradation, while a two-phase kinetics behavior was found for the oxidative degradation. The degradation products were characterized by mass spectrometry and nuclear magnetic resonance spectroscopy. Dehydration, epimerization and N-oxidation were the main processes observed during the degradation of galantamine. Moreover, if sufficient material could be isolated the inhibitory activity against the target enzyme acetylcholinesterase was also assessed. PMID:21300511

Marques, Lygia Azevedo; Maada, Ismail; de Kanter, Frans J J; Lingeman, Henk; Irth, Hubertus; Niessen, Wilfried M A; Giera, Martin

2011-04-28

128

Development and validation of stability-indicating HPLC method for determination of cefpirome sulfate.  

PubMed

The stability-indicating LC assay method was developed and validated for quantitative determination of cefpirome sulfate (CPS) in the presence of degradation products formed during the forced degradation studies. An isocratic HPLC method was developed with Lichrospher RP-18 column, 5 ?m particle size, 125 mm x 4 mm column and 12 mM ammonium acetate-acetonitrile (90 : 10 v/v) as a mobile phase. The flow rate of the mobile phase was 1.0 mL/min. Detection wavelength was 270 nm and temperature was 30 degrees C. Cefpirome sulfate as other cephalosporins was subjected to stress conditions of degradation in aqueous solutions including hydrolysis, oxidation, photolysis and thermal degradation. The developed method was validated with regard to linearity, accuracy, precision, selectivity and robustness. The method was applied successfully for identification and determination of cefpirome sulfate in pharmaceuticals and during kinetic studies. PMID:25362801

Zalewski, Przemys?aw; Skibi?ski, Robert; Cielecka-Piontek, Judyta; Bednarek-Rajewska, Katarzyna

2014-01-01

129

Stability indicating HPLC method for the simultaneous determination of moxifloxacin and prednisolone in pharmaceutical formulations  

PubMed Central

Background A simple, specific, and fast stability indicating reverse phase liquid chromatographic method was established for instantaneous determination of moxifloxacin and prednisolone in bulk drugs and pharmaceutical formulations. Results Optimum chromatographic separations among the moxifloxacin, prednisolone and stress-induced degradation products were achieved within 10 minutes by use of BDS Hypersil C8 column (250 X 4.6 mm, 5 ?m) as stationary phase with mobile phase consisted of a mixture of phosphate buffer (18 mM) containing 0.1% (v/v) triethylamine, at pH 2.8 (adjusted with dilute phosphoric acid) and methanol (38:62 v/v) at a flow rate of 1.5 mL min-1. Detection was performed at 254 nm using diode array detector. The method was validated in accordance with ICH guidelines. Response was a linear function of concentrations over the range of 20–80 ?g mL-1 for moxifloxacin (r2 ? 0.998) and 40–160 ?g mL-1 for prednisolone (r2 ? 0.998). The method was resulted in good separation of both the analytes and degradation products with acceptable tailing and resolution. The peak purity index for both the analytes after all types of stress conditions was ? 0.9999 indicated a complete separation of both the analyte peaks from degradation products. The method can therefore, be regarded as stabilityindicating. Conclusions The developed method can be applied successfully for simultaneous determination of moxifloxacin and prednisolone in pharmaceutical formulations and their stability studies. PMID:22947049

2012-01-01

130

STABILITY OF THE PHOTON INDICES IN Z-SOURCE GX 340+0 FOR SPECTRAL STATES  

SciTech Connect

We show an analysis of the spectral and timing properties of X-ray radiation from Z-source GX 340+0 during its evolution when the electron temperature of the transition layer (TL) kT{sub e} monotonically decreases from 21 to 3 keV. We analyze episodes observed with BeppoSAX and RXTE. We reveal that the X-ray broadband energy spectra during all spectral states can be reproduced by a physical model composed of a soft Blackbody component and two Comptonized components (both due to the presence of the TL that upscatters both seed photons of T{sub s1} {approx}< 1 keV coming from the disk (first component Comptb1), and seed photons of temperature T{sub s2} {approx}< 1.5 keV coming from the neutron star (second component Comptb2) and the iron-line (Gaussian) component. Spectral analysis using this model indicates that the photon power-law indices {Gamma}{sub com1} and {Gamma}{sub com2} of the Comptonized components are almost constant, {Gamma}{sub com1} and {Gamma}{sub com2} {approx} 2 when kT{sub e} changes from 3 to 21 keV along the Z-track. We interpret the detected quasi-stability of the indices of Comptonized components to be near a value of 2. Furthermore, this index stability now found for the Comptonized spectral components of Z-source GX 340+0 is similar to that previously established in the atoll sources 4U 1728-34 and GX 3+1, and earlier proposed for a number of X-ray neutron stars (NSs). This behavior of NSs both for atoll and Z-sources is essentially different from that observed in black hole binaries where {Gamma}{sub com} increases during a spectral evolution from the low state to the high state and ultimately saturates at a high mass accretion rate.

Seifina, Elena [Moscow State University/Sternberg Astronomical Institute, Universitetsky Prospect 13, Moscow 119992 (Russian Federation)] [Moscow State University/Sternberg Astronomical Institute, Universitetsky Prospect 13, Moscow 119992 (Russian Federation); Titarchuk, Lev; Frontera, Filippo, E-mail: seif@sai.msu.ru, E-mail: titarchuk@fe.infn.it, E-mail: lev@milkyway.gsfc.nasa.gov, E-mail: frontera@fe.infn.it [Dipartimento di Fisica, Universita di Ferrara, Via Saragat 1, I-44122 Ferrara (Italy)] [Dipartimento di Fisica, Universita di Ferrara, Via Saragat 1, I-44122 Ferrara (Italy)

2013-03-20

131

Stability Indicating LC-Method for Estimation of Paracetamol and Lornoxicam in Combined Dosage Form  

PubMed Central

A simple, specific and stability indicating reversed phase high performance liquid chromatographic method was developed for the simultaneous determination of paracetamol and lornoxicam in tablet dosage form. A Brownlee C-18, 5 ?m column having 250×4.6 mm i.d. in isocratic mode, with mobile phase containing 0.05 M potassium dihydrogen phosphate:methanol (40:60, v/v) was used. The flow rate was 1.0 ml/min and effluents were monitored at 266 nm. The retention times of paracetamol and lornoxicam were 2.7 min and 5.1 min, respectively. The linearity for paracetamol and lornoxicam were in the range of 5–200 ?g/ml and 0.08–20 ?g/ml, respectively. Paracetamol and lornoxicam stock solutions were subjected to acid and alkali hydrolysis, chemical oxidation and dry heat degradation. The proposed method was validated and successfully applied to the estimation of paracetamol and lornoxicam in combined tablet dosage form. PMID:21617776

Shah, Dimal A.; Patel, Neel J.; Baldania, Sunil L.; Chhalotiya, Usman K.; Bhatt, Kashyap K.

2011-01-01

132

Degradation Pathway for Eplerenone by Validated Stability Indicating UP-LC Method  

PubMed Central

Degradation pathway for eplerenone is established as per ICH recommendations by validated and stability-indicating reverse phase liquid chromatographic method. Eplerenone is subjected to stress conditions of acid, base, oxidation, and thermal and photolysis. Significant degradation is observed in acid and base stress conditions. Four impurities are studied and the major degradant (RRT about 0.31) was identified by LC-MS and spectral analysis. The stress samples are assayed against a qualified reference standard and the mass balance is found close to 99.5%. Efficient chromatographic separation is achieved on a Waters symmetry C18 stationary phase with simple mobile phase combination delivered in gradient mode and quantification is carried at 240?nm at a flow rate of 1.0?mL?min?1. In the developed LC method the resolution between eplerenone and four potential impurities (imp-1, imp-2, imp-3, and imp-4) is found to be greater than 4.0. Regression analysis shows an r value (correlation coefficient) of greater than 0.999 for eplerenone and four potential impurities. This method is capable to detect the impurities of eplerenone at a level of 0.020% with respect to test concentration of 1.0?mg?mL?1 for a 20??L injection volume. The developed UPLC method is validated with respect to specificity, linearity and range, accuracy, precision, and robustness for impurities and assay determination. PMID:23097723

Sudhakar Babu, Kondru; Madireddy, Venkataramanna; Indukuri, Venkata Somaraju

2012-01-01

133

Degradation Pathway for Eplerenone by Validated Stability Indicating UP-LC Method.  

PubMed

Degradation pathway for eplerenone is established as per ICH recommendations by validated and stability-indicating reverse phase liquid chromatographic method. Eplerenone is subjected to stress conditions of acid, base, oxidation, and thermal and photolysis. Significant degradation is observed in acid and base stress conditions. Four impurities are studied and the major degradant (RRT about 0.31) was identified by LC-MS and spectral analysis. The stress samples are assayed against a qualified reference standard and the mass balance is found close to 99.5%. Efficient chromatographic separation is achieved on a Waters symmetry C18 stationary phase with simple mobile phase combination delivered in gradient mode and quantification is carried at 240?nm at a flow rate of 1.0?mL?min(-1). In the developed LC method the resolution between eplerenone and four potential impurities (imp-1, imp-2, imp-3, and imp-4) is found to be greater than 4.0. Regression analysis shows an r value (correlation coefficient) of greater than 0.999 for eplerenone and four potential impurities. This method is capable to detect the impurities of eplerenone at a level of 0.020% with respect to test concentration of 1.0?mg?mL(-1) for a 20??L injection volume. The developed UPLC method is validated with respect to specificity, linearity and range, accuracy, precision, and robustness for impurities and assay determination. PMID:23097723

Sudhakar Babu, Kondru; Madireddy, Venkataramanna; Indukuri, Venkata Somaraju

2012-01-01

134

Spatial scale of similarity as an indicator of metacommunity stability in exploited marine systems.  

PubMed

The spatial scale of similarity among fish communities is characteristically large in temperate marine systems: connectivity is enhanced by high rates of dispersal during the larval/juvenile stages and the increased mobility of large-bodied fish. A larger spatial scale of similarity (low beta diversity) is advantageous in heavily exploited systems because locally depleted populations are more likely to be "rescued" by neighboring areas. We explored whether the spatial scale of similarity changed from 1970 to 2006 due to overfishing of dominant, large-bodied groundfish across a 300 000-km2 region of the Northwest Atlantic. Annually, similarities among communities decayed slowly with increasing geographic distance in this open system, but through time the decorrelation distance declined by 33%, concomitant with widespread reductions in biomass, body size, and community evenness. The decline in connectivity stemmed from an erosion of community similarity among local subregions separated by distances as small as 100 km. Larger fish, of the same species, contribute proportionally more viable offspring, so observed body size reductions will have affected maternal output. The cumulative effect of nonlinear maternal influences on egg/larval quality may have compromised the spatial scale of effective larval dispersal, which may account for the delayed recovery of certain member species. Our study adds strong support for using the spatial scale of similarity as an indicator of metacommunity stability both to understand the spatial impacts of exploitation and to refine how spatial structure is used in management plans. PMID:22471094

Shackell, Nancy L; Fisher, Jonathan A D; Frank, Kenneth T; Lawton, Peter

2012-01-01

135

Photodegradation kinetics, cytotoxicity assay and determination by stability-indicating HPLC method of mianserin hydrochloride.  

PubMed

A stability-indicating HPLC method for the determination of mianserin hydrochloride in coated tablets was developed and validated. Also, drug photodegradation kinetics and cytotoxicity were determined. Chromatographic analyses were performed in an Ace RP-18 octadecyl silane column (250 mm x 4.6 mm i.d., particle size 5 microm) maintained at ambient temperature (25 degrees C). The mobile phase was composed of methanol, 50 mM monobasic potassium phosphate buffer and 0.3% triethylamine solution adjusted to pH 7.0 with phosphoric acid 10% (85:15, v/v) in isocratic mode at a flow rate of 1.0 mL x min(-1). The performed degradation conditions were: acid and basic media with HCl 1.0 M and NaOH 1.0 M, respectively, oxidation with H2O2 3% and the exposure to UV-C light. No interference in the mianserin hydrochloride elution was verified by degradation products formed. Linearity was assessed and ANOVA showed non-significant linearity deviation (p > 0.05). Adequate results were obtained for repeatability, intermediate precision, accuracy and robustness. The photodegradation kinetics of mianserin hydrochloride was evaluated in methanol. The degradation of mianserin could be better described as zero order kinetic (r = 0.9982). The UV-C degraded samples of mianserin hydrochloride were also studied in order to determine the preliminary cytotoxicity in vitro against mononuclear cells. PMID:22822535

Sfair, L L; Graeff, J S; Paim, C S; Passos, C S; Steppe, M; Schapoval, E E S

2012-06-01

136

Stability indicating MEKC method for the determination of gliclazide and its specified impurities.  

PubMed

A stability indicating-micellar electrokinetic chromatography method was developed and validated for the determination of gliclazide (GCZ) and its specified impurities, gliclazide impurities B (GZB) and F (GZF) in bulk and tablets. The analytes were well separated (Rs>2.1) in 5min using 10mM phosphate buffer (pH 7.0) containing 15mM sodium dodecyl sulfate on a fused-silica capillary with an effective length of 40cm and an inner diameter of 50?m, injection at 50mbar for 5s, temperature of 25°C, applied voltage of 20kV and photodiode array detection at 225nm. The method showed good linearity (r(2)>0.99, in the ranges of 128-192, 20-60 and 10-50?g/mL for GCZ, GZB and GZF, respectively) and precision (%RSD for intra- and inter-day precision of less than 2.00%, n=3) for all compounds. Accuracy represented as %recovery was between 99.1 and 100.1% with %RSDs of less than 0.59% (n=3). Limits of detection and quantitation were less than 40 and 120?g/mL, respectively. The method was robust with %RSDs of migration time and peak areas of less than 1.36% (n=9), when buffer and separating voltage were altered around the optimal values. Stress tests showed that GCZ was stable in alkaline hydrolysis both at room and elevated temperature. However, GCZ degraded under acid and neutral hydrolysis and oxidation condition. Elevated temperature and exposure to sunlight accelerated GCZ degradation and formation of GZB and an unknown degradation product. Stability profiles and degradation kinetics of GCZ could be established using the MEKC method. In addition, the method could be used for assay of GCZ in raw material and commercial tablets and results revealed that contents of GCZ in all samples were within the pharmacopeia limit. No degradation products, especially GZB and GZF, were observed in the investigated samples. PMID:25260054

Doomkaew, Athiporn; Prutthiwanasan, Brompoj; Suntornsuk, Leena

2015-01-01

137

Stability-indicating HPLC Method for Simultaneous Determination of Terbutaline Sulphate, Bromhexine Hydrochloride and Guaifenesin  

PubMed Central

The aim of the present study was the development and subsequent validation of a simple, precise and stability-indicating reversed phase HPLC method for the simultaneous determination of guaifenesin, terbutaline sulphate and bromhexine hydrochloride in the presence of their potential impurities in a single run. The photolytic as well as hydrolytic impurities were detected as 3,5-dihydroxybenzoic acid, 3,5-dihydroxybenzaldehyde, 1-(3,5-dihydroxyphenyl)-2-[(1,1-dimethylethyl) amino]-ethanone from terbutaline, 2-methoxyphenol and an unknown impurity identified as (2RS)-3-(2-hydroxyphenoxy)-propane-1,2-diol from guaifenesin. The chromatographic separation of all the three active components and their impurities was achieved on Wakosil II column, using phosphate buffer (pH 3.0) and acetonitrile as mobile phase which was delivered initially in the ratio of 80:20 (v/v) for 18 min, then changed to 60:40 (v/v) for next 12 min, and finally equilibrated back to 80:20 (v/v) for 10 min. Other HPLC parameters were: Flow rate at 1.0 ml/min, detection wavelengths 248 and 280 nm, injection volume 10 ?l. The calibration graphs plotted with five concentrations of each component were linear with a regression coefficient R2 >0.9999. The limit of detection and limit of quantitation were estimated for all the five impurities. The established method was then validated for linearity, precision, accuracy, and specificity and demonstrated to be applicable to the determination of the active ingredients in commercial and model cough syrup. No interference from the formulation excipients was observed. These results suggest that this LC method can be used for the determination of multiple active ingredients and their impurities in a cough and cold syrup. PMID:22131621

Porel, A.; Haty, Sanjukta; Kundu, A.

2011-01-01

138

Clonal Stability of Blood Cell Lineages Indicated by X-Chromosomal Transcriptional Polymorphism  

Microsoft Academic Search

Summary The idea that stem cells oscillate between a state of activity and dormancy, thereby giving rise to differentiating progeny either randomly or in orderly clonal succession, has important impli- cations for understanding normal hematopoiesis and blood cell dyscrasias. The degree of clonal stability in individuals also has practical implications for the evaluation of clonal lympho- myeloproliferative diseases. To evaluate

Josef T. Prchal; Jaroslav E Prchal; Monika Belickova; Shande Chen; Yongli Guan; G. Larry Gartlandfl; Max D. Cooperll

1996-01-01

139

Evaluation of acoustic attenuation as an indicator of roof stability in advancing headings  

Microsoft Academic Search

A novel acoustic technique developed to monitor roof stability in advancing headings was evaluated during a field monitoring trial at the Brunswick Mine, New Brunswick, Canada. The acoustic technique uses waveforms generated by mining activity near the active face (such as rotary-percussion drilling for the installation of support or drilling blast-holes) to identify changes in the attenuation properties of the

S. D. Butt; C. Mukherjee; G. Lebans

2000-01-01

140

Forced Degradation Study on Gliclazide and Application of Validated Stability-Indicating HPLC-UV Method in Stability Testing of Gliclazide Tablets  

Microsoft Academic Search

Forced degradation study on gliclazide was conducted under the conditions of hydrolysis, oxidation, dry heat and photolysis\\u000a and an isocratic stability-indicating HPLC-UV method was developed and validated. All the seven degradation products (I–VII)\\u000a formed under different conditions were optimally resolved on a C18 column with mobile phase composed of 40% acetonitrile and 60% ammonium acetate solution (0.025 M, pH 3.5) at

Gulshan Bansal; Manjeet Singh; Kaur Chand Jindal

2007-01-01

141

Ab-initio simulations of chemical stability indicators of the bis-DGA-type molecule and its radiation degradation products  

SciTech Connect

For hydrometallurgical treatment of the high level liquid waste (HLLW) in the DIAMEX and SANEX processes, organic compounds of the bis-DGA family are used as cation extractants in apolar solvents. For the compound of m-xylylene-bis-diglycolamide high distribution coefficients for Eu and Am were found. Since the environment of the process is highly radioactive and acidic (nitric acid), it is necessary to ensure the stability of the extractants. In order to analyse the process theoretically, the molecule of m-xylylene-bis- diglycolamide and two of its degradation products were simulated by the DFT computational methods (PBE, RPBE, BLYP, B3LYP) available within the simulation environment DMol{sup 3} 6.1 and Gaussian 09 software. The local chemical stability of some locations of the molecule was assessed from the calculated stability indicators (electrostatic potential, Fukui function, HOMO localization). In connection with the chemical treatment, especially the stability against an electrophilic attack was tested. The results of calculated bond orders and spatial distribution of electrostatic potential and HOMO were are successfully correlated with the local and general stability determined by the experiment. These results should be helpful for the further development of the separation process. (authors)

Koubsky, T.; Kalvoda, L.; Drab, M. [Czech Technical University in Prague, Faculty of Nuclear Sciences and Physical Engineering, Dept. of Solid State Engineering, Trojanova 13, 120 00 Prague 2 (Czech Republic)

2013-07-01

142

Stability-indicating high performance thin layer chromatography determination of Paroxetine hydrochloride in bulk drug and pharmaceutical formulations  

Microsoft Academic Search

A simple selective precise and stability-indicating high performance thin layer chromatographic method of analysis of Paroxetine hydrochloride both as a bulk drug and in formulations was developed and validated. The method employed TLC (Thin Layer Chromatography) aluminum precoated with silica gel 60F-254 as the stationary phase. The solvent system consisted of butanol:acetic acid:water (8:2:0.5, v\\/v\\/v). This system was found to

A. Venkatachalam; Vidya S. Chatterjee

2007-01-01

143

DEVELOPMENT OF A VALIDATED STABILITY INDICATING LC METHOD FOR QUANTITATIVE DETERMINATION OF AN ANTISPASMODIC DRUG AND ITS RELATED SUBSTANCES  

Microsoft Academic Search

Present article describes development and validation of stability indicating liquid chromatographic method for quantitative determination of ?-cyclohexyl-?-hydroxy-benzeneacetic acid-4-(diethylamino)-2-butynyl ester hydrochloride a potential antispasmodic and anticholinergic drug and its four impurities (related substances) using a Zorbax SB-Cyano column and mobile phase consisting of aqueous buffer (0.20% triethylamine) and acetonitrile in the ratio 49:51 and with a pH 6.3. The developed LC

Nandini R. Pai; Deepnandan S. Dubhashi

2010-01-01

144

Stability-indicating methods for the determination of pipazethate HCl in the presence of its alkaline degradation product  

Microsoft Academic Search

Three different accurate, sensitive and reproducible stability-indicating methods for the determination of pipazethate HCl in the presence of its alkaline degradation product are presented. The first method is based on ratio-spectra 1st derivative (RSD1) spectrophotometry of the drug at 305nm, over a concentration range of 10–70?gmL?1 with mean percentage recovery of 99.69±1.10. The second method utilises quantitative densitometric evaluation of

Yasser S. El-Saharty; Nariman A. El-Ragehy; Heba M. Abdel-Monem; Mohammed I. Abdel-Kawy

2010-01-01

145

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

Microsoft Academic Search

Spectrophotometric, spectrodensitometric and HPLC are stability indicating methods described for determination of Zaleplon in pure and dosage forms.As Zaleplon is easily degradable, the proposed techniques in this manuscript are adopted for its determination in presence of its alkaline degradation product, namely N-[4-(3-cyano-pyrazolo[1,5a]pyridin-7-yl)-phenyl]-N-ethyl-acetamide. These approaches are successfully applied to quantify Zaleplon using the information included in the absorption spectra of appropriate

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

2007-01-01

146

STABILITY-INDICATING HPLC METHOD FOR DETERMINATION OF OFLOXACIN IN BULK DRUG AND TABLETS USING TRIFLUOROACETATE AS COUNTER ANIONS  

Microsoft Academic Search

A stability-indicating reversed-phase HPLC method for the quantitative determination of ofloxacin in bulk samples and tablet formulation has been developed and validated. The separation was performed on a C18 column (4.6 × 250 mm, 5 µm) using an isocratic mobile phase comprising of acetonitrile and buffer pH 3.3 (16: 84, v\\/v) with a diode array UV\\/Vis detection at 294 nm. The buffer was composed of

Jankana Burana-Osot; Kamonchanok Saowakul; Chak Charoensilpchai; Nattawat Surapeepong; Wisut Pongsiriwan; Anchalee Kumsum

2012-01-01

147

A STABILITY-INDICATING HPLC METHOD FOR DETERMINATION OF OFLOXACIN IN BULK DRUG AND TABLETS USING TRIFLUOROACETATE AS COUNTER ANIONS  

Microsoft Academic Search

A stability-indicating reversed-phase HPLC method for the quantitative determination of ofloxacin in bulk samples and tablet formulation has been developed and validated. The separation was performed on a C18 column (4.6 × 250 mm, 5 µm) using an isocratic mobile phase comprising of acetonitrile and buffer pH 3.3 (16: 84, v\\/v) with a diode array UV\\/Vis detection at 294 nm. The buffer was composed of

Jankana Burana-osot; Kamonchanok Saowakul; Chak Charoensilpchai; Nattawat Surapeepong; Wisut Pongsiriwan; Anchalee Kumsum

2012-01-01

148

Amphiphile-induced vesiculation in aged hereditary spherocytosis erythrocytes indicates normal membrane stability properties under  

E-print Network

Amphiphile-induced vesiculation in aged hereditary spherocytosis erythrocytes indicates normal protein or ankyrin were incubated with amphiphiles (detergents) at sublytic concentrations (378C, 60 min erythrocytes (1%). Control and HS cells responded, however, similarly to amphiphile-treatment (non

Iglic, Ales

149

Figure-ground processing during fixational saccades in V1: indication for higher-order stability.  

PubMed

In a typical visual scene we continuously perceive a "figure" that is segregated from the surrounding "background" despite ongoing microsaccades and small saccades that are performed when attempting fixation (fixational saccades [FSs]). Previously reported neuronal correlates of figure-ground (FG) segregation in the primary visual cortex (V1) showed enhanced activity in the "figure" along with suppressed activity in the noisy "background." However, it is unknown how this FG modulation in V1 is affected by FSs. To investigate this question, we trained two monkeys to detect a contour embedded in a noisy background while simultaneously imaging V1 using voltage-sensitive dyes. During stimulus presentation, the monkeys typically performed 1-3 FSs, which displaced the contour over the retina. Using eye position and a 2D analytical model to map the stimulus onto V1, we were able to compute FG modulation before and after each FS. On the spatial cortical scale, we found that, after each FS, FG modulation follows the stimulus retinal displacement and "hops" within the V1 retinotopic map, suggesting visual instability. On the temporal scale, FG modulation is initiated in the new retinotopic position before it disappeared from the old retinotopic position. Moreover, the FG modulation developed faster after an FS, compared with after stimulus onset, which may contribute to visual stability of FG segregation, along the timeline of stimulus presentation. Therefore, despite spatial discontinuity of FG modulation in V1, the higher-order stability of FG modulation along time may enable our stable and continuous perception. PMID:24573283

Gilad, Ariel; Pesoa, Yair; Ayzenshtat, Inbal; Slovin, Hamutal

2014-02-26

150

Stability-indicating spectrofluorimetric method for determination of itopride hydrochloride in raw material and pharmaceutical formulations.  

PubMed

A simple, sensitive and rapid spectrofluorimetric method for determination of itopride hydrochloride in raw material and tablets has been developed. The proposed method is based on the measurement of the native fluorescence of the drug in water at 363 nm after excitation at 255 nm. The relative fluorescence intensity-concentration plot was rectilinear over the range of 0.1-2 ?g/mL (2.5?×?10(-7)-5.06?×?10(-6) mole/L), with good correlation (r?=?0.9999), limit of detection of 0.015 ?g/mL and a lower limit of quantification of 0.045 ?g/mL. The described method was successfully applied for the determination of itopride hydrochloride in its commercial tablets with average percentage recovery of 100.11?±?0.32 without interference from common excipients. Additionally, the proposed method can be applied for determination of itopride in combined tablets with rabeprazole or pantoprazole without prior separation. The method was extended to stability study of itopride. The drug was exposed to acidic, alkaline, oxidative and photolytic degradation according to ICH guidelines. Moreover, the method was utilized to investigate the kinetics of the alkaline, acidic and oxidative degradation of the drug. A proposal for the degradation pathways was postulated. PMID:23852162

Walash, Mohamed I; Ibrahim, Fawzia; Eid, Manal I; El Abass, Samah Abo

2013-11-01

151

Age and thermal stability of particulate organic matter fractions indicate the presence of black carbon in soil  

NASA Astrophysics Data System (ADS)

Black carbon (BC) from incomplete combustion is abundant in many soils. The age of black carbon is often higher than that of typical soil organic carbon (SOC) owing to its higher recalcitrance against microbial decomposition compared to plant residues. Also fossil BC may contribute to the high age of SOC. At the same time, the oxidative thermal stability of BC is known to be higher than that of SOC due to its chemical and physical structure. For a meaningful application of radiocarbon as an indicator for soil carbon age and turnover, the relative contribution of BC needs to be known but BC is difficult to separate physically from soil. Here we analyze particulate organic carbon (POC) fractions from four different field sites in Europe for their thermal stability using oxidative differential scanning calorimetry (DSC) and for their radiocarbon signature. POC may be particularly sensitive to BC 'contamination' because it was gained using a combination of size and density separation. One of these sites is essentially free of measurable amounts of BC. Each of the four sites comprised between five and eight individual POC samples taken from different spots. The radiocarbon signature and the calculated POC mean residence time of samples from three out of four sites indicated the presence of very old carbon, resulting in mean residence times (MRT) of several hundreds and up to 3700 years. In contrast, MRT's of POC from the virtually BC-free site were between 50 and 100 years. Two indicators for thermal stability of the POC fractions, i) the amount of heat released at temperatures > 450 °C and ii) the amount of heat released at 500 °C (where the latter represents the peak temperature of charcoal isolated from one of the samples) correlated both significantly and non-linearly with the samples MRT, indicating that samples with high BC content are older. Hence we can conclude that for an individual site with increasing abundance of BC both the age and the thermal stability of POC fractions increase. However, only in the case of samples from one site thermal stability proved to be a reliable predictor for the generic presence of BC whereas for the other two BC containing sites the thermal signals were not significantly different to the site free of BC.

Leifeld, Jens; Heiling, Maria; Hajdas, Irka

2014-05-01

152

Application of a Validated, Stability-Indicating LC Method to Stress Degradation Studies of Ramipril and Moexipril.HCl  

Microsoft Academic Search

A stability-indicating reversed-phase liquid chromatographic (RPLC) method has been established for analysis of ramipril (RAM)\\u000a and moexipril hydrochloride (MOEX.HCl) in the presence of the degradation products generated in studies of forced decomposition.\\u000a The drug substances were subjected to stress by hydrolysis (0.1 m NaOH and 0.1 m HCl), oxidation (30% H2O2), photolysis (254 nm), and thermal treatment (80 °C). The drugs were degraded under

Abdalla A. Elshanawane; Samia M. Mostafa; Mohamed S. Elgawish

2008-01-01

153

A Stability-indicating High Performance Liquid Chromatographic Assay for the Simultaneous Determination of Atenolol and Lercanidipine Hydrochloride in Tablets  

PubMed Central

A simple, rapid, precise and accurate isocratic reversed phase stability indicating HPLC method was developed and validated for the simultaneous determination of atenolol and lercanidipine hydrochloride in commercial tablets. The chromatographic separation was achieved on phenomenex Gemini C18 (250×4.6 mm, 5 ?m) column using a mobile phase consisting of acetonitrile and buffer (20 mM potassium dihydrogen phosphate pH 3.5) in the ratio of (55:45, v/v) at a flow rate of 1.0 ml/min and UV detection at 235 nm. The linearity of the proposed method was investigated in the range of 40-160 ?g/ml (r2=0.9995) for atenolol and 8-32 ?g/ml (r2=0.9993) for lercanidipine. Degradation products produced as a result of stress studies did not interfere with the detection of atenolol and lercanidipine and the assay can thus be considered stability-indicating. PMID:22707819

Kaila, H. O.; Ambasana, M. A.; Thakkar, R. S.; Saravaia, H. T.; Shah, A. K.

2011-01-01

154

Stability-indicating HPTLC method for simultaneous determination of nateglinide and metformin hydrochloride in pharmaceutical dosage form  

PubMed Central

A stability indicating high performance thin layer chromatography (HPTLC) method was developed and validated for determination of two anti-diabetic drugs, nateglinide and metformin hydrochloride in co-formulations. Study was performed on pre-coated silica gel HPTLC plates using chloroform:ethyl acetate:acetic acid (4:6:0.1 v/v/v) as the mobile phase. A TLC scanner set at 216 nm was used for direct evaluation of the chromatograms in the reflectance/absorbance mode. Method was validated according to ICH guidelines. The correlation coefficients of calibration curves were found to be 0.996 and 0.995 in the concentration range of 200–2400 and 500–3000 ng band?1 for nateglinide and metformin, respectively. The method had an accuracy of 99.72% for nateglinide and 100.08% for metformin hydrochloride. The method had the potential to determine these drugs simultaneously from dosage forms without any interference of the tablets excipients. Nateglinide and metformin hydrochloride were also subjected to acid, base, oxidation, wet, heat and photo-degradation studies. The degradation products obtained were well resolved from the pure drugs with significantly different Rf values. As the method could effectively separate the drugs from its degradation products, it can be used for stability-indicating analysis. PMID:23960763

Thomas, Asha Byju; Patil, Shrikrushna Digambar; Nanda, Rabindra Kumar; Kothapalli, Lata Prasad; Bhosle, Shital Shridhar; Deshpande, Avinash Devidas

2011-01-01

155

A Stability-indicating High Performance Liquid Chromatographic Assay for the Simultaneous Determination of Atenolol and Lercanidipine Hydrochloride in Tablets.  

PubMed

A simple, rapid, precise and accurate isocratic reversed phase stability indicating HPLC method was developed and validated for the simultaneous determination of atenolol and lercanidipine hydrochloride in commercial tablets. The chromatographic separation was achieved on phenomenex Gemini C18 (250×4.6 mm, 5 ?m) column using a mobile phase consisting of acetonitrile and buffer (20 mM potassium dihydrogen phosphate pH 3.5) in the ratio of (55:45, v/v) at a flow rate of 1.0 ml/min and UV detection at 235 nm. The linearity of the proposed method was investigated in the range of 40-160 ?g/ml (r(2)=0.9995) for atenolol and 8-32 ?g/ml (r(2)=0.9993) for lercanidipine. Degradation products produced as a result of stress studies did not interfere with the detection of atenolol and lercanidipine and the assay can thus be considered stability-indicating. PMID:22707819

Kaila, H O; Ambasana, M A; Thakkar, R S; Saravaia, H T; Shah, A K

2011-07-01

156

Stability indicating HPLC-UV method for detection of curcumin in Curcuma longa extract and emulsion formulation.  

PubMed

A stability-indicating HPLC-UV method for the determination of curcumin in Curcuma longa extract and emulsion was developed. The system suitability parameters, theoretical plates (N), tailing factor (T), capacity factor (K'), height equivalent of a theoretical plate (H) and resolution (Rs) were calculated. Stress degradation studies (acid, base, oxidation, heat and UV light) of curcumin were performed in emulsion. It was found that N>6500, T<1.1, K' was 2.68-3.75, HETP about 37 and Rs was 1.8. The method was linear from 2 to 200?g/mL with a correlation coefficient of 0.9998. The intra-day precision and accuracy for curcumin were ?0.87% and ?2.0%, while the inter-day precision and accuracy values were ?2.1% and ?-1.92. Curcumin degraded in emulsion under acid, alkali and UV light. In conclusion, the stability-indicating method could be employed to determine curcumin in bulk and emulsions. PMID:25306352

Syed, Haroon Khalid; Liew, Kai Bin; Loh, Gabriel Onn Kit; Peh, Kok Khiang

2015-03-01

157

A validated stability-indicating HPLC method for the simultaneous determination of pheniramine maleate and naphazoline hydrochloride in pharmaceutical formulations  

PubMed Central

Background A simple, rapid, and accurate stability-indicating reverse phase liquid chromatographic method was developed and validated for the simultaneous determination of pheniramine maleate and naphazoline hydrochloride in bulk drugs and pharmaceutical formulations. Results Optimum chromatographic separations among pheniramine maleate, naphazoline hydrochloride and stress-induced degradation products have been achieved within 10 minutes by using an Agilent zorbax eclipse XDB C18 column (150 mm?×?4.6 mm, 5 ?m) as the stationary phase with a mobile phase consisted of 10 mM phosphate buffer pH 2.8 containing 0.5% triethlamine and methanol (68:32, v/v) at a flow rate of 1 mL min-1. Detection was performed at 280 nm using a diode array detector. Theoretical plates for pheniramine maleate and naphazoline hydrochloride were calculated to be 6762 and 6475, respectively. The method was validated in accordance with ICH guidelines with respect to linearity, accuracy, precision, robustness, specificity, limit of detection and quantitation. Regression analysis showed good correlations (R2?>?0.999) for pheniramine maleate in the concentration range of 150–1200 ?g mL-1 and naphazoline hydrochloride in 12.5-100 ?g mL-1. The method results in excellent separation of both the analytes and degradation products. The peak purity factor is ?980 for both analytes after all types of stress, indicating complete separation of both analyte peaks from the stress induced degradation products. Conclusions Overall, the proposed stability-indicating method was suitable for routine quality control and drug analysis of pheniramine maleate and naphazoline hydrochloride in pharmaceutical formulations. PMID:24485011

2014-01-01

158

3D fluorescence-based characterization of dissolved organic matter components and their impact on soil-structure stability indices  

NASA Astrophysics Data System (ADS)

Stable soil aggregates and structure are usually associated with increased levels of soil organic matter. A significant fraction of the latter is comprised of humic substances (HS). Opposing findings on the contribution of HS to both stabilization and increased dispersivity of soil aggregates have been reported; these findings could be related to the heterogeneity in the chemical composition of the HS. The objectives of this research were: (i) to characterize the compositional heterogeneity of HS and dissolved organic matter (DOM) in soil solutions, (ii) to evaluate the relations between general soil properties (e.g., organic matter, clay and calcium carbonate content, cation exchange capacity) and concentration and composition of DOM and HS in soil solution, and (iii) to examine the relationships between properties associated with soil structure such as aggregate stability and hydraulic conductivity and the composition of DOM and HS. The composition of HS and DOM in aqueous extracts, obtained from samples collected from cultivated fields of four Israeli soils (loamy sand, loam, sandy clay and clay), was characterized and quantified using 3D fluorescence (and UV-absorption) spectroscopy together with parallel factor analysis (PARAFAC) supported by dissolved organic carbon (DOC) measurements. Variability in the HS/DOM composition was obtained by including soils with a different history of irrigation, i.e. irrigated by fresh water and by treated wastewater. PARAFAC analysis provided scores proportional to concentrations of three major fluorescent DOM components, two were considered to represent HS and the third to represent proteinous matter (containing tryptophan). Soil structure had been characterized by saturated hydraulic conductivity and an index for aggregate stability. PARAFAC analysis demonstrated that concentrations of fluorescent DOM components in aqueous extracts were influenced by the type of water used for irrigation. This influence was distinctly affected by soil type. In clayey soils, samples irrigated with treated wastewater yielded smaller concentrations of extractable HS components compared with samples irrigated with fresh water. In the loamy sand and loam, concentrations of HS and proteinous matter in samples irrigated with treated wastewater were greater than those from samples irrigated with freshwater. These differences suggest that some interactions between soil clay and the effluent-borne OM may occur leading to reduced extractability of organic components in the clayey soils. The structural stability determinants of soils studied correlated significantly (at the p<0.05 level) with the concentrations of the three fluorescent DOM components but not with DOC concentration. In the clayey soils, the decrease in soil stability indices correlated with the decrease in concentrations of the extractable HS components, both induced by irrigation with treated wastewater. Our results suggest that changes in soil indices representing soil structure and stability, induced by changes in irrigation water quality, could be associated with changes in the concentration of HS components.

Levy, Guy; Lordian, Anna; Borisover, Mikhail

2010-05-01

159

Development and Validation of Stability-indicating HPLC Method for Betamethoasone Dipropionate and Related Substances in Topical Formulation  

PubMed Central

A gradient reversed phase HPLC method was developed and validated for analysis of betamethasone dipropionate, its related substances and degradation products, using Altima C18 column (250×4.6 mm, 5 ?m) with a flow rate of 1.0 ml/min and detection wavelength of 240 nm. The mobile phase A is a mixture of water, tetrahydrofuran and acetonitrile in the ratio of 90:4:6 (v/v/v) while mobile phase B is a mixture of acetonitrile, tetrahydrofuran, water and methanol in the ratio of 74:2:4:20 (v/v/v/v). The samples were analyzed using 20 ?l injection volume and the column temperature was maintained at 50°. The limit of detection and limit of quantitation were found to be 0.02 ?g/ml and 0.07 ?g/ml, respectively. The stability-indicating capability of method was established by forced degradation studies and method demonstrated successful separation of drug, its related substances and degradation products. The method was validated as per the International Conference on Harmonization guidelines. The developed method is linear in the range of 0.07 to 200% of specification limits established for all the known related substances; betamethasone17-propionate, betamethasone 21-propionate, betamethasone 17-propionate-21-acetate (RSD <5, 2, 1%, respectively, r2=09991-0.9999 for sample concentration of 100 ?g/ml). The method is sensitive, specific, linear, accurate, precise and stability indicating for the quantitation of drug, its related substances and other degradation compounds. PMID:23325990

Vairale, A. S.; Sivaswaroop, P.; Bandana, S.

2012-01-01

160

Development and Validation of Stability-indicating HPLC Method for Betamethoasone Dipropionate and Related Substances in Topical Formulation.  

PubMed

A gradient reversed phase HPLC method was developed and validated for analysis of betamethasone dipropionate, its related substances and degradation products, using Altima C(18) column (250×4.6 mm, 5 ?m) with a flow rate of 1.0 ml/min and detection wavelength of 240 nm. The mobile phase A is a mixture of water, tetrahydrofuran and acetonitrile in the ratio of 90:4:6 (v/v/v) while mobile phase B is a mixture of acetonitrile, tetrahydrofuran, water and methanol in the ratio of 74:2:4:20 (v/v/v/v). The samples were analyzed using 20 ?l injection volume and the column temperature was maintained at 50°. The limit of detection and limit of quantitation were found to be 0.02 ?g/ml and 0.07 ?g/ml, respectively. The stability-indicating capability of method was established by forced degradation studies and method demonstrated successful separation of drug, its related substances and degradation products. The method was validated as per the International Conference on Harmonization guidelines. The developed method is linear in the range of 0.07 to 200% of specification limits established for all the known related substances; betamethasone17-propionate, betamethasone 21-propionate, betamethasone 17-propionate-21-acetate (RSD <5, 2, 1%, respectively, r(2)=09991-0.9999 for sample concentration of 100 ?g/ml). The method is sensitive, specific, linear, accurate, precise and stability indicating for the quantitation of drug, its related substances and other degradation compounds. PMID:23325990

Vairale, A S; Sivaswaroop, P; Bandana, S

2012-03-01

161

Folding Properties of Cytosine Monophosphate Kinase from E. coli Indicate Stabilization through an Additional Insert in the NMP Binding Domain  

PubMed Central

The globular 25 kDa protein cytosine monophosphate kinase (CMPK, EC ID: 2.7.4.14) from E. coli belongs to the family of nucleoside monophosphate (NMP) kinases (NMPK). Many proteins of this family share medium to high sequence and high structure similarity including the frequently found ?/? topology. A unique feature of CMPK in the family of NMPKs is the positioning of a single cis-proline residue in the CORE-domain (cis-Pro124) in conjunction with a large insert in the NMP binding domain. This insert is not found in other well studied NMPKs such as AMPK or UMP/CMPK. We have analyzed the folding pathway of CMPK using time resolved tryptophan and FRET fluorescence as well as CD. Our results indicate that unfolding at high urea concentrations is governed by a single process, whereas refolding in low urea concentrations follows at least a three step process which we interpret as follows: Pro124 in the CORE-domain is in cis in the native state (Nc) and equilibrates with its trans-isomer in the unfolded state (Uc - Ut). Under refolding conditions, at least the Ut species and possibly also the Uc species undergo a fast initial collapse to form intermediates with significant amount of secondary structure, from which the trans-Pro124 fraction folds to the native state with a 100-fold lower rate constant than the cis-Pro124 species. CMPK thus differs from homologous NMP kinases like UMP/CMP kinase or AMP kinase, where folding intermediates show much lower content of secondary structure. Importantly also unfolding is up to 100-fold faster compared to CMPK. We therefore propose that the stabilizing effect of the long NMP-domain insert in conjunction with a subtle twist in the positioning of a single cis-Pro residue allows for substantial stabilization compared to other NMP kinases with ?/? topology. PMID:24205218

Beitlich, Thorsten; Lorenz, Thorsten; Reinstein, Jochen

2013-01-01

162

A Sensitive RP-HPLC Method for Simultaneous Estimation of Diethylcarbamazine and Levocetirizine in Tablet Formulation.  

PubMed

A simple, sensitive and reproducible method was developed and validated for the simultaneous estimation of diethylcarbamazine and levocetirizine in its tablet formulation by reverse phase high performance liquid chromatography using Waters1515 HPLC with UV detector at the ?(max) of 224 nm, using Princeton Sphere-100 C(18) (250×4.6 mm. 5 ?) column. The mobile phase used was 20mM potassium dihydrogen orthophosphate buffer (pH: 3.2):acetonitrile (50:50 v/v) with isocratic flow (flow rate 1 ml/min) and the pH was adjusted with orthophosphoric acid. Losartan potassium was used as an internal standard. The compounds diethylcarbamazine, levocetirizine and losartan potassium were eluted at 2.12, 4.27 and 5.96 min, respectively. The peaks were eluted with better resolution. The method was accurate with assay values of 96.32 and 93.04% w/w, precise (%RSD) with intra-day 1.72 and 1.89 and inter-day 1.85 and 1.92, recoveries 102.86 and 101.1% w/w, which are very sensitive with limit of detections (LOD)'s 75, 50 ng/ml and limit of quantification (LOQ)'s 100, 75 ng/ml and linear with R(2) values 0.994 in the range of 5 to 30 ?g/ml 0.1 to 1 ?g/ml for diethylcarbamazine and levocetirizine, respectively. Hence this method can be applied for quantification of different formulations containing diethylcarbamazine and levocetirizine simultaneously. PMID:22457560

Reddy, J Mahesh; Jeyaprakash, M R; Madhuri, K; Meyyanathan, S N; Elango, K

2011-05-01

163

Ion-pairing RP-HPLC method for determining tetrazene in water and soil  

Microsoft Academic Search

Ion-pairing reversed phase-high performance liquid chromatography methods were developed to determine tetrazene in water and soil. Determinations were achieved using an LC-18 column, a mobile phase of 2\\/3 v\\/v methanol-water containing 0.01 M 1-decane-sulfonic acid sodium salt, and a UV detector set at 280 nm. The pH of the mobile phase was adjusted to 3 with glacial acetic acid, which

Marianne E. Walsh; Thomas F. Jenkins

1989-01-01

164

Separation of Selected Flavonoids by use of RP?HPLC\\/NP?HPTLC Coupled Methods  

Microsoft Academic Search

Phenolic compounds, such as phenolic acids, flavonoids, flavonoid glycosides, and resveratrol, were chromatographed on thin?layers of silica in various eluent systems. Systems with the highest selectivity were chosen. Also, reversed?phase HPLC systems were optimized for the separation of investigated compounds and most the selective system was applied for the separation of two phenolic extracts – Polygonum avicularis and Polygonum hydropiper.

Miros?aw A. Hawry?; Janusz Makar

2007-01-01

165

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

PubMed

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

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

2014-05-01

166

Simultaneous determination of aceclofenac, paracetamol, and chlorzoxazone by RP-HPLC in pharmaceutical dosage form.  

PubMed

A simple, rapid, and precise reversed-phase liquid chromatographic method is developed for simultaneous determination of paracetamol, aceclofenac, and chlorzoxazone in their ternary mixtures of commercial pharmaceutical preparation. This method uses a Zorbax SB C18, 250 x 4.6 mm, 5 microm analytical column. Mobile phase is acetonitrile and buffer (40:60, v/v), buffer containing 50 mM orthophosporic acid; pH of the buffer is adjusted to 6 with 10% w/v sodium hydroxide solution. The instrumental settings are at a flow rate of 1 mL/min; the column temperature is 25 degrees C, and detector wavelength is 270 nm. The sample concentrations are measured on weight basis to avoid the internal standard. The method is validated and shown to be linear. The correlation coefficients for paracetamol, aceclofenac, and chlorzoxazone are 0.9981, 0.9990, and 0.9986, respectively. The recovery values for paracetamol, aceclofenac, and chlorzoxazone ranged from 100.7-101.4%, 100.4-101.0%, and 100.5-101.3%, respectively. The relative standard deviation for six replicates is always less than 2%. This HPLC method is successfully applied to the simultaneous quantitative analysis of the title drugs in tablets and can be applied for assay and dissolution test of tablets for the estimation of paracetamol, aceclofenac, and chlorozoxazone in their commercial samples. PMID:18718143

Shaikh, K A; Devkhile, A B

2008-08-01

167

Analysis of RP-HPLC loading conditions for maximizing peptide identifications in shotgun proteomics  

PubMed Central

Substantial energy and resources have been invested in improving mass spectrometry (MS) instrumentation, up-stream sample preparation protocols, and database search strategies to maximize peptide and protein identifications. The role of HPLC sample loading methods in maximizing MS identifications has been largely overlooked, and there exists an immense heterogeneity in the methods employed in the proteomics literature. We sought to optimize loading methods by testing multiple loading conditions (buffer composition, resin, initial gradient) using tryptic digests of an 18 protein mixture and whole yeast lysate. The loading buffer acetonitrile (ACN) concentration greatly affected peptide identifications: up to a 26% increase in peptide identifications was observed by decreasing the ACN concentration from 5% to 2% during sample loading. Hydrophilic peptides were the main contributors to the increase in peptide identifications and, at higher ACN concentrations, were washed from the pre-column during desalting. Sampling of the hydrophilic peptides was enhanced by using a shallow initial ACN gradient. The results were found to be resin-specific and not generalizable. Our investigation demonstrates the often unappreciated importance of optimizing sample loading conditions to reflect the aims of the research and the characteristics of the LC configurations employed. PMID:19601632

Peterson, Amelia; Hohmann, Laura; Huang, Li; Kim, Bong; Eng, Jimmy K.; Martin, Daniel B.

2009-01-01

168

Sorption of certain isatins on various sorbents under RP-HPLC conditions  

NASA Astrophysics Data System (ADS)

The results from chromatographic analysis of biologically active isatin derivatives on hyper-crosslinked polystyrene (HCLPS) and silica gel modified by octadecyl groups (SilC18) are presented. The constants of distribution of sorbates between a mobile phase and the investigated sorbents ( K x ) and the changes in the standard differential molar Gibbs energies of adsorption (? _a bar G^circ ) are calculated, along with the chromatographic retention-physicochemical property of sorbate dependences. It is found that the equations describing these dependences have high forecasting ability with respect to the values of retention factors of the investigated sorbates.

Konstantinov, A. V.; Shafigulin, R. V.; Il'in, M. M.; Davankov, V. A.; Bulanova, A. V.; Purygin, P. P.

2013-06-01

169

Development and validation of RP-HPLC method for quantification of glipizide in biological macromolecules.  

PubMed

Glipizide (GPZ) has been widely used in the treatment of type-2 diabetics as insulin secretogague. Multiunit chitosan based GPZ floating microspheres was prepared by ionotropic gelation method for gastroretentive delivery using sodiumtripolyphosphate as cross-linking agent. Pharmacokinetic study of microspheres was done in rabbit and plasma samples were analyzed by a newly developed and validated high-performance liquid chromatographic method. Method was developed on Hypersil ODS-18 column using a mobile phase of 10mM phosphate buffer (pH, 3.5) and methanol (25:75, v/v). Elute was monitored at 230 nm with a flow rate of 1 mL/min. Calibration curve was linear over the concentration range of 25.38-2046.45 ng/mL. Retention times of GPZ and internal standard (gliclazide) were 7.32 and 9.02 min respectively. Maximum plasma drug concentration, area under the plasma drug concentration-time curve and elimination half life for GPZ floating microspheres were 2.88±0.29 ?g mL(-1), 38.46±2.26 ?g h mL(-1) and 13.55±1.36 h respectively. When the fraction of drug dissolved from microspheres in pH 7.4 was plotted against the fraction of drug absorbed, a linear correlation (R(2)=0.991) was obtained in in vitro and in vivo correlation study. PMID:24418334

Pani, Nihar Ranjan; Acharya, Sujata; Patra, Sradhanjali

2014-04-01

170

RP-HPLC simultaneous estimation of betulinic acid and ursolic acid in Carissa spinarum.  

PubMed

Carissa spinarum is a well-known medicinal plant which has been reported for its anthelmintic, antipyretic, antiviral, antimicrobial and antitumour activities. In this study, a reverse-phase high-performance liquid chromatographic method was developed for the simultaneous estimation of betulinic acid (BA) and ursolic acid (UA) in the methanol extract of C. spinarum root. The method was further validated for linearity, limit of detection (LOD = 3.3?/S), limit of quantification (LOQ = 10?/S), precision, accuracy and ruggedness. The linear response was obtained using the equation, y = 511.5x+17603 (r(2) = 0.9920) and y = 2886x+6821 (r(2) = 0.9935) for BA and UA, respectively. The LOD and LOQ were found to be 0.268 ± 0.520 ?g mL(- 1), 0.878 ± 0.183 ?g mL(- 1) for BA (0.58% w/w) and 3.140 ± 0.36 ?g mL(- 1), 8.820 ± 0.85 ?g mL(- 1) for UA (1.09% w/w), respectively. The %RSD of precision and recovery of BA and UA was < 2.0%. The proposed method was simple, accurate, specific, precise and reproducible. PMID:25167761

Chanda, Joydeb; Mukherjee, Pulok K; Harwansh, Ranjit; Bhadra, Santanu; Chaudhary, Sushil K; Choudhury, Shuvasish

2014-11-01

171

Determination and quantification of cetirizine HCl in dosage formulations by RP-HPLC.  

PubMed

A simple, sensitive, reliable and rapid HPLC method for the determination of cetirizine hydrochloride using hyoscine butyl bromide as an internal standard has been developed. The chromatographic system consisted of Shimadzu LC-10 AT VP pump, SPD-10 AV VP with UV/visible detector and a CBM-102 Bus Module integrator. Separation was achieved on the U Bondapak 125 A C18 10 microm column at room temperature. The samples were introduced through an injector valve with a 10 microl sample loop. Acetonitrile-water (1:1 v/v) was used as mobile phase, with flow rate 2 ml/minute. pH was adjusted to 2.9 with phosphoric acid. UV detection was performed at 205 nm. The results obtained showed a good agreement with the declared content. Recovery values for cetirizine hydrochloride were 99.19-100.82%. The proposed method is reliable rapid, precise, selective and may be used for the quantitative analysis of cetirizine HCl, in presence of hyoscine butyl bromide as internal standard. The method was valid was for the determination in raw materials, bulk drug and formulations. The limit of quantification was 5-30 nano grams, while the limit of detection was 0.4 nano grams. PMID:16380337

Arayne, M Saeed; Sultana, Najma; Siddiqui, Farhan Ahmed

2005-07-01

172

RP-HPLC Determination of Tiger Nut and Orgeat Amino Acid Contents  

Microsoft Academic Search

The amino acid profile of 11 samples of tiger nuts (Cyperus esculentusL.) grown in the area of “L'Horta Nord” in Valencia (Spain) and one sample of African origin were determined, along with the amino acid contents of 10 samples of natural orgeat from Valencia. Protein was hydrolysed by hydrochloric acid at 110 °C for 23 h, and amino acids were

L. Bosch; A. Alegría; R. Farré

2005-01-01

173

Gradient HPLC-DAD stability indicating determination of miconazole nitrate and lidocaine hydrochloride in their combined oral gel dosage form.  

PubMed

The pharmaceutical combination of miconazole nitrate (MZ) and lidocaine hydrochloride (LD) is used in the curative and prophylactic therapy of the oral and gastro-intestinal infections caused by Candida albicans. To the best of our knowledge, no attempts have yet been made to assay this combination by any analytical method. A simple and selective high-performance liquid chromatography-diode array detection (HPLC-DAD) stability-indicating method was developed for the simultaneous determination of MZ and LD in their combined formulation. Effective chromatographic separation was achieved using a Zorbax SB-C8 column with gradient elution of the mobile phase composed of 0.05 M phosphoric acid and acetonitrile. The gradient elution started with 25% (by volume) acetonitrile, ramped up linearly to 65% in 6 min, then kept constant until the end of the run. The mobile phase was pumped at a flow rate of 1 mL/min. The multiple wavelength detector was set at 215 nm and analytes were quantified by measuring their peak areas. The retention times for LD and MZ were approximately 4.1 and 8.4 min, respectively. The reliability and analytical performance of the proposed HPLC procedure were statistically validated with respect to linearity, ranges, precision, accuracy, selectivity, robustness, detection and quantification limits. Calibration curves were linear in the ranges of 5-100 µg/ml for both drugs with correlation coefficients > 0.999. Both drugs were subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal degradation. The proposed method proved to be stability-indicating by the resolution of the two analytes from the related substance and potential impurity (2,6-dimethylaniline) and from the forced-degradation products. The validated HPLC method was applied to the analysis of MZ and LD in the combined oral gel preparation, in which the two analytes were successfully quantified and resolved from the pharmaceutical additives. The proposed method made use of DAD as a tool for peak identity and purity confirmation. PMID:22407005

Belal, Tarek S; Haggag, Rim S

2012-05-01

174

Stability-indicating simultaneous determination of paracetamol and three of its related substances using a direct GC/MS method.  

PubMed

A simple, direct, and selective stability-indicating GC/MS procedure was developed for the simultaneous determination of paracetamol (PR) and three of its related substances: 4-aminophenol (4-AP), acetanilide (AD), and 4'-chloroacetanilide (4-CA). The method involved resolution of the underivatized compounds using a 100% dimethylpolysiloxane (Rtx-1) column, and MS detection was carried out in the electron-impact mode. The four compounds were completely resolved in less than 11 min. The fragmentation pathways for the four compounds were described, and the structures of the major fragment ions peaks were proposed. Quantification of the analytes was based on measuring their peak areas. The reliability and analytical performance of the proposed method including linearity, range, precision, accuracy, and detection and quantification limits were statistically validated. Calibration curves were linear over the ranges 75-500, 25-350, 25-350, and 25-350 microg/mL for PR, 4-AP, AD, and 4-CA, respectively. The proposed method was successfully applied for the determination of PR and its related substances in laboratory-prepared mixtures of different proportions. Also, it was applied for the assay of PR in several commercially available pharmaceutical formulations with recoveries of 98.95-100.76%. PMID:20166578

Belal, Tarek; Awad, Tamer; Clark, C Randall

2009-01-01

175

Stability-indicating Reversed-phase Liquid Chromatographic Method for Simultaneous Determination of Losartan Potassium and Ramipril in Tablets  

PubMed Central

A stability-indicating reversed-phase liquid chromatographic method has been developed and validated for simultaneous determination of losartan potassium and ramipril. Separations were achieved using a C18 column with mobile phase consisting of acetonitrile and (0.2% v/v, pH 2.5) aqueous trifluoroacetic acid (45:55, v/v) in isocratic mode at 1 ml/min flow rate. Column effluent was monitored at 210 nm using a UV detector. The method was validated for selectivity, linearity, accuracy, precision, sensitivity and robustness. Novel microwave-assisted forced degradation technique was employed for evaluation of selectivity. The method demonstrated excellent linearity for losartan potassium and ramipril with regression coefficients of 0.9999 and 0.9998, respectively. The linearity range was found to be 62.5-5000 ng/ml and 125-10,000 ng/ml with the mean percentage recoveries of 100.36% (±2.27) and 100.16% (±3.33) for losartan potassium and ramipril, respectively. In a robustness study, a full factorial design revealed that the analytical response remains unaffected by small variations in the critical chromatographic factors. The method was found to be sensitive with quantification limits of 44.30 and 79.93 ng/ml for losartan potassium and ramipril. The method was successfully employed for the determination of losartan potassium and ramipril in commercially available and in-house prepared tablets. PMID:23440900

Kollipara, S.; Bende, G.; Bansal, Y.; Saha, R.

2012-01-01

176

A validated stability-indicating liquid chromatographic method for determination of degradation impurities and diastereomers in voriconazole tablets.  

PubMed

A reversed-phase gradient liquid chromatographic method has been developed for the quantitative determination of Voriconazole, along with its degradation and diastereomeric impurities in tablet dosage form. Chromatographic separation has been achieved on an Inertsil ODS 3V, 150 × 4.6 mm, 5 ?m column. The mobile phase consisting of solvent A 0.05 molar (M) potassium dihydrogen phosphate (pH 2.5 buffer) and solvent B (mixture of acetonitrile and methanol in the ratio 90:10 (v/v)), was delivered at a flow rate of 1.2 mL min(-1) with the detection wavelength at 256 nm. Resolution of Voriconazole and all five potential impurities was achieved at greater than 2.0 for all pairs of compounds. The drug was subjected to stress conditions such as oxidative, acid and base hydrolysis, and thermal and photolytic degradation. Voriconazole was found to degrade significantly under base hydrolysis stress conditions compared to acid hydrolysis stress conditions. The degradation products were well-resolved from the main peak and its impurities, thus proving the stability-indicating power of the method. The stressed samples were assayed against a reference standard and the mass balance was found to be close to 99.0%. The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision, and robustness. PMID:23264937

Shaikh, Kabeer A; Patil, Ashish T

2012-12-01

177

A validated stability indicating ultra performance liquid chromatographic method for determination of impurities in Esomeprazole magnesium gastro resistant tablets.  

PubMed

A novel gradient reversed-phase ultra performance liquid chromatographic method has been developed for quantitative determination of Esomeprazole magnesium and its seven impurities in pharmaceutical dosage forms. Chromatographic separation has been achieved on an Acquity BEH C18, 50mm×2.1mm, 1.7?m with buffered mobile phase consisting solvent A (0.04molar (M) glycine (pH 9.0) buffer) and solvent B (mixture of acetonitrile and Milli-Q water in the ratio 90: 10 (v/v); respectively) delivered at flow rate of 0.21mL min(-1) and the detection wavelength 305nm. Resolution of Esomeprazole magnesium and all the seven potential impurities has been achieved greater than 2.0 for all pairs of compounds. The drug was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. Esomeprazole magnesium was found to degrade significantly in oxidative and acid hydrolysis stress conditions and stable in base, hydrolytic and photolytic degradation conditions. The degradation products were well resolved from main peak and its impurities, thus proved the stability indicating power of the method. The stress samples were assayed against a reference standard and the mass balance was found to be close to 99.1%. So this method was also suitable for Assay determination of Esomeprazole magnesium in pharmaceutical dosage forms. The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness. PMID:21920688

Nalwade, Santaji Uttam; Reddy, Vangala Ranga; Rao, Dantu Durga; Morisetti, Nagendra Kumar

2012-01-01

178

Stability-indicating methods for the determination of a mixture of almitrine and raubasine by derivative spectrophotometry.  

PubMed

A second-derivative spectrophotometric method ((2)D) and a derivative ratio spectrum zero crossing ((1)DD) method were used to determine raubasine and almitrine dismesylate in the presence of raubasine degradation product, using methanol as a solvent. Linear relationships were obtained in the range from 6-20 microg ml(-1) raubasine for the ((2)D) method and 12-24 microg ml(-1) almitrine dismesylate for the ((1)DD) method. By applying these methods it was possible to determine raubasine in its pure powdered form with an accuracy of 99.93 +/- 1.116 (n = 8) for the ((2)D) method and almitrine dismesylate with an accuracy of 99.98 +/- 0.602 (n = 7) for the ((1)DD) method.Laboratory-prepared mixtures containing different ratios of raubasine, almitrine dismesylate and raubasine degradation product were analysed and the proposed methods were valid up to 50% of raubasine degradation product. They were found to be suitable stability-indicating assay methods for raubasine and almitrine dismesylate in pharmaceutical formulations. PMID:20355207

El-Sayed, Mohammad A

2009-06-01

179

Validating a Stability Indicating HPLC Method for Kinetic Study of Cetirizine Degradation in Acidic and Oxidative Conditions  

PubMed Central

A stability indicating High-Performance Liquid Chromatography (HPLC) method was validated and used to study the degradation of cetirizine dihydrochloride in acidic and oxidative conditions. The separation was carried out on a Symmetry C18 column and a mixture of 50 mM KH2PO4 and acetonitrile (60:40 v/v, pH = 3.5) was used as the mobile phase. The method was linear over the range of 1-20 ?g/mL of cetirizine dihydrochloride (r2 > 0.999) and the within-day and between-day precision values were less than 1.5%. The results showed that cetirizine dihydrochloride was unstable in 2 M HCl and 0.5% H2O2. The kinetics of the acidic degradation showed a pseudo-first-order reaction in the temperature range of 70-90°C. In addition, the kinetics of hydrogen peroxide mediated degradation was pseudo-first-order in the temperature range of 50-80°C. PMID:24250602

Souri, Effat; Hatami, Ali; Shabani Ravari, Nazanin; Alvandifar, Farhad; Barazandeh Tehrani, Maliheh

2013-01-01

180

Impact of fluorination on proteolytic stability of peptides: a case study with ?-chymotrypsin and pepsin.  

PubMed

Protease stability is a key consideration in the development of peptide-based drugs. A major approach to increase the bioavailability of pharmacologically active peptides is the incorporation of non-natural amino acids. Due to the unique properties of fluorine, fluorinated organic molecules have proven useful in the development of therapeutically active small molecules as well as in materials and crop science. This study presents data on the ability of fluorinated amino acids to influence proteolytic stability when present in peptide sequences that are based on ideal protease substrates. Different model peptides containing fluorinated amino acids or ethylglycine in the P2, P1'or P2' positions were designed according to the specificities of the serine protease, ?-chymotrypsin (EC 3.4.21.1) or the aspartic protease, pepsin (EC 3.4.23.1). The proteolytic stability of the peptides toward these enzymes was determined by an analytical RP-HPLC assay with fluorescence detection and compared to a control sequence. Molecular modeling was used to support the interpretation of the structure-activity relationship based on the analysis of potential ligand-enzyme interactions. Surprisingly, an increase in proteolytic stability was observed only in a few cases. Thus, this systematic study shows that the proteolytic stability of fluorinated peptides is not predictable, but rather is a very complex phenomenon that depends on the particular enzyme, the position of the substitution relative to the cleavage site and the fluorine content of the side chain. PMID:25193166

Asante, Vivian; Mortier, Jérémie; Wolber, Gerhard; Koksch, Beate

2014-12-01

181

Validation of a high performance liquid chromatography method for the stabilization of epigallocatechin gallate.  

PubMed

Epigallocatechin gallate (EGCG) is a green tea catechin with potential health benefits, such as anti-oxidant, anti-carcinogenic and anti-inflammatory effects. In general, EGCG is highly susceptible to degradation, therefore presenting stability problems. The present paper was focused on the study of EGCG stability in HEPES (N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid) medium regarding the pH dependency, storage temperature and in the presence of ascorbic acid a reducing agent. The evaluation of EGCG in HEPES buffer has demonstrated that this molecule is not able of maintaining its physicochemical properties and potential beneficial effects, since it is partially or completely degraded, depending on the EGCG concentration. The storage temperature of EGCG most suitable to maintain its structure was shown to be the lower values (4 or -20°C). The pH 3.5 was able to provide greater stability than pH 7.4. However, the presence of a reducing agent (i.e., ascorbic acid) was shown to provide greater protection against degradation of EGCG. A validation method based on RP-HPLC with UV-vis detection was carried out for two media: water and a biocompatible physiological medium composed of Transcutol(®)P, ethanol and ascorbic acid. The quantification of EGCG for purposes, using pure EGCG, requires a validated HPLC method which could be possible to apply in pharmacokinetic and pharmacodynamics studies. PMID:25175728

Fangueiro, Joana F; Parra, Alexander; Silva, Amélia M; Egea, Maria A; Souto, Eliana B; Garcia, Maria L; Calpena, Ana C

2014-11-20

182

Validated stability-indicating HPLC method for the determination of pridinol mesylate. Kinetics study of its degradation in acid medium  

Microsoft Academic Search

The stability of pridinol mesylate (PRI) was investigated under different stress conditions, including hydrolytic, oxidative, photolytic and thermal, as recommended by the ICH guidelines. Relevant degradation was found to take place under acidic (0.1N HCl) and photolytic (visible and long-wavelength UV-light) conditions, both yielding the product resulting from water elimination (ELI), while submission to an oxidizing environment gave the N-oxidation

Romina M. Bianchini; Patricia M. Castellano; Teodoro S. Kaufman

2008-01-01

183

Sunlight Inactivation of Fecal Indicator Bacteria and Bacteriophages from Waste Stabilization Pond Effluent in Fresh and Saline Waters  

Microsoft Academic Search

Sunlight inactivation in fresh (river) water of fecal coliforms, enterococci, Escherichia coli, somatic coli- phages, and F-RNA phages from waste stabilization pond (WSP) effluent was compared. Ten experiments were conducted outdoors in 300-liter chambers, held at 14°C (mean river water temperature). Sunlight inactivation (kS) rates, as a function of cumulative global solar radiation (insolation), were all more than 10 times

Lester W. Sinton; Carollyn H. Hall; Philippa A. Lynch; Robert J. Davies-Colley

2002-01-01

184

Variation in sediment stability and relation to indicators of microbial abundance in the Okura Estuary, New Zealand  

Microsoft Academic Search

Secretions of mucus by benthic microbes potentially bind estuarine intertidal sediment, thus affecting stability by raising the erosion threshold. Existing models for predicting onset of erosion—such as the Shields diagram—have been built from laboratory studies of abiotic sediments, hence their accuracy when applied to natural sediment may be limited. In this study, variability in critical shear velocity (u*crit) of natural

S. D. Lelieveld; C. A. Pilditch; M. O. Green

2003-01-01

185

Chromium Oxidation State in Planetary Basalts: Oxygen Fugacity Indicator and Critical Variable for Cr-Spinel Stability  

NASA Technical Reports Server (NTRS)

Cr is a ubiquitous and relatively abundant minor element in basaltic, planetary magmas. At the reduced oxidation states (stability and Cr concentration of magmatic phases such as spinel, clinopyroxene, and olivine. However, understanding the Cr valence in quenched melts has historically been plagued with analytical issues, and only recently has reliable methodology for quantifying Cr valence in quenched melts been developed. Despite this substantial difficulty, the pioneering works of Hanson and Jones and Berry and O'Neill provided important insights into the oxidation state of Cr in in silicate melts. Here we present a series of 1-bar gas mixing experiments performed with a Fe-rich basaltic melt in which have determined the Cr redox ratio of the melt at over a range of fO2 values by measuring this quantity in olivine with X-ray Absorption Near Edge Spectroscopy (XANES). The measured Cr redox ratio of the olivine phenocrysts can be readily converted to the ratio present in the conjugate melt via the ratio of crystal-liquid partition coefficients for Cr3+ and Cr2+. We have applied these results to modeling Cr spinel stability and Cr redox ratios in a primitive, iron-rich martian basalt.

Bell, A. S.; Burger, P. V.; Le, Loan; Papike, J. J.; Jone, J.; Shearer, C. K.

2014-01-01

186

Simultaneous determination of some water-soluble vitamins and preservatives in multivitamin syrup by validated stability-indicating high-performance liquid chromatography method  

Microsoft Academic Search

HPLC stability-indicating method has been developed for the simultaneous determination of some water-soluble vitamins (ascorbic acid, thiamine hydrochloride, riboflavin-5?-phosphate sodium, pyridoxine hydrochloride, nicotinamide, d(+)-panthenol) and two preservatives (methylparaben and sodium benzoate) in multivitamin syrup preparation. Water-soluble vitamins, preservatives and their degradants were separated on Zorbax SB-Aq (C18) (250mm×4.6mm, 5?m) column at an ambient temperature. Combined isocratic and gradient elution was

Stojanka Vidovi?; Biljana Stojanovi?; Jelena Veljkovi?; Ljiljana Praži?-Arsi?; Goran Rogli?; Dragan Manojlovi?

2008-01-01

187

A stability-indicating high performance liquid chromatographic (HPLC) assay for the simultaneous determination of atorvastatin and amlodipine in commercial tablets  

Microsoft Academic Search

A simple, rapid, precise and accurate isocratic reversed-phase stability-indicating HPLC method was developed and validated for the simultaneous determination of atorvastatin (AT) and amlodipine (AM) in commercial tablets. The method has shown adequate separation for AM, AT from their associated main impurities and their degradation products. Separation was achieved on a Perfectsil® Target ODS-3, 5?m, 250mm×4.6mm i.d. column using a

A. Mohammadi; N. Rezanour; M. Ansari Dogaheh; F. Ghorbani Bidkorbeh; M. Hashem; R. B. Walker

2007-01-01

188

Development and Validation of a Stability-Indicating HPLC Method for Determination of Ciprofloxacin Hydrochloride and its Related Compounds in Film-Coated Tablets  

Microsoft Academic Search

The objective of the current study was the development and subsequent validation of a simple, sensitive, precise and stability-indicating\\u000a reversed-phase HPLC method for the determination of ciprofloxacin HCl in pharmaceutical dosage forms in the presence of its\\u000a potential impurities. The chromatographic separation of ciprofloxacin HCl and its related compounds was achieved on an Inertsil\\u000a ODS3 column using UV detection. The

B. Aksoy; ?. Küçükgüzel; S. Rollas

2007-01-01

189

Stability-indicating high performance liquid chromatographic determination of raubasine in its binary mixture with kinetic study of raubasine acid degradation  

Microsoft Academic Search

Stability-indicative determination of raubasine (RAB) in the presence of its degradate and its binary mixture with almitrine dismesylate (ALM) was investigated. The degradation product had been isolated, via acid-degradation, characterized and confirmed. Selective quantification of RAB and ALM in bulk form, pharmaceutical formulations and\\/or in the presence of RAB degradate was demonstrated. The analytical technique adopted for quantification was high

Mohammad A. El-Sayed

2011-01-01

190

A SINGLE COMMON STABILITY INDICATING ULTRA-PERFORMANCE LIQUID CHROMATOGRAPHIC METHOD FOR ESTIMATION OF IMPURITIES IN FOUR ANGIOTENSIN II RECEPTOR BLOCKERS  

Microsoft Academic Search

A novel single common stability-indicating gradient reverse phase ultra-performance liquid chromatographic (RP-UPLC) method was developed for the determination of purity of four angiotensin II receptor blockers namely valsartan, losartan potassium, irbesartan, and telmisartan from respective finished dosage forms in the presence of their impurities and forced degradation products. The method was developed using Waters Aquity BEH C18 column with mobile

Dantu Durga Rao; Galla Vamsi Krishna; A. Malleswara Reddy; L. Kalyanaraman; K. Kyas

2012-01-01

191

Stability-indicating micelle-enhanced spectrofluorimetric method for determination of loratadine and desloratadine in dosage forms.  

PubMed

A highly sensitive and simple spectrofluorimetric method was developed for the determination of loratadine (LRT) and desloratadine (DSL) in their pharmaceutical formulations. The proposed method is based on investigation of the fluorescence spectral behaviour of LRT and DSL in a sodium dodecyl sulphate (SDS) micellar system. In aqueous solution of acetate buffer of pH 4.5, the fluorescence intensities of both LRT and DSL were greatly enhanced (240%) in the presence of SDS. The fluorescence intensity was measured at 438 nm after excitation at 290 nm for both drugs. The fluorescence-concentration plots were rectilinear over the range 0.05-2.0 µg/mL for both LRT and DSL, with lower detection limits of 5.13 × 10(-3) and 6.35 × 10(-3) µg/mL for LRT and DSL, respectively. The method was successfully applied to the analysis of the two drugs in their commercial tablets, capsules and syrups, and the results were in good agreement with those obtained with the official or comparison methods. The proposed method is specific for the determination of LRT in the presence of other co-formulated drugs, such as pseudoephedrine. The application of the proposed method was extended to stability studies of LRT and DSL after exposure to different forced degradation conditions, such as acidic, alkaline and oxidative conditions, according to ICH guidelines. PMID:21491578

Walash, M I; Belal, F; El-Enany, N; Eid, M; El-Shaheny, R N

2011-01-01

192

Development and validation of a stability-indicating reversed-phase high performance liquid chromatography method for assay of betamethylepoxide and estimation of its related compounds.  

PubMed

Betamethylepoxide (16beta-methyl-Delta(1,4)-pregnadiene-9beta-11beta-oxide-17alpha,21-diol-3,20-dione) is a key intermediate for the synthesis of various active pharmaceutical ingredients (APIs) of steroid compounds. A stability-indicating reversed-phase HPLC method for assay of betamethylepoxide and estimation of its related compounds has been developed and validated. This method can accurately quantitate betamethylepoxide in the presence of numerous structurally related compounds (including the alpha-epimer, known as alphamethylepoxide). This method can also adequately separate most of the impurities from each other and estimate their quantities in betamethylepoxide samples. The stability-indicating capability of this method has been demonstrated by adequate separation of the degradation products from betamethylepoxide in stress degraded and aged stability samples. The HPLC column used in the method was a 5 cm YMC Hydrosphere C(18) column (4.6 mm I.D.) and the mobile phase consisted of (A) water and (B) acetonitrile:methanol (8:25, v/v). PMID:17512937

Xiao, Kang Ping; Chien, Dwight; Markovich, Robert; Rustum, Abu M

2007-07-20

193

Altered Neuronal Markers Following Treatment with Mood Stabilizer and Antipsychotic Drugs Indicate an Increased Likelihood of Neurotransmitter Release  

PubMed Central

Objective Given the ability of mood stabilizers and antipsychotics to promote cell proliferation, we wanted to determine the effects of these drugs on neuronal markers previously reported to be altered in subjects with psychiatric disorders. Methods Male Sprauge-Dawley rats were treated with vehicle (ethanol), lithium (25.5 mg per day), haloperidol (0.1 mg/kg), olanzapine (1.0 mg/kg) or a combination of lithium and either of the antipsychotic drugs for 28 days. Levels of cortical synaptic (synaptosomal associated protein-25, synaptophysin, vesicle associated protein and syntaxin) and structural (neural cell adhesion molecule and alpha-synuclein) proteins were determined in each treatment group using Western blots. Results Compared to the vehicle treated group; animals treated with haloperidol had greater levels of synaptosomal associated protein-25 (p<0.01) and neural cell adhesion molecule (p<0.05), those treated with olanzapine had greater levels of synaptophysin (p<0.01) and syntaxin (p<0.01). Treatment with lithium alone did not affect the levels of any of the proteins. Combining lithium and haloperidol resulted in greater levels of synaptophysin (p<0.01), synaptosomal associated protein-25 (p<0.01) and neural cell adhesion molecule (p<0.01). The combination of lithium and olanzapine produced greater levels of synaptophysin (p<0.01) and alpha-synuclein (p<0.05). Conclusion Lithium alone had no effect on the neuronal markers. However, haloperidol and olanzapine affected different presynaptic markers. Combining lithium with olanzapine additionally increased alpha-synuclein. These drug effects need to be taken into account by future studies examining presynaptic and neuronal markers in tissue from subjects with psychiatric disorders. PMID:23429852

Dean, Brian

2012-01-01

194

A Stability-Indicating HPLC-DAD Method for Determination of Stiripentol: Development, Validation, Kinetics, Structure Elucidation and Application to Commercial Dosage Form  

PubMed Central

A rapid, simple, sensitive, and accurate isocratic reversed-phase stability-indicating high performance liquid chromatography method has been developed and validated for the determination of stiripentol and its degradation product in its bulk form and pharmaceutical dosage form. Chromatographic separation was achieved on a Symmetry C18 column and quantification was achieved using photodiode array detector (DAD). The method was validated in accordance with the ICH requirements showing specificity, linearity (r2 = 0.9996, range of 1–25??g/mL), precision (relative standard deviation lower than 2%), accuracy (mean recovery 100.08 ± 1.73), limits of detection and quantitation (LOD = 0.024 and LOQ = 0.081??g/mL), and robustness. Stiripentol was subjected to various stress conditions and it has shown marked stability under alkaline hydrolytic stress conditions, thermal, oxidative, and photolytic conditions. Stiripentol degraded only under acidic conditions, forming a single degradation product which was well resolved from the pure drug with significantly different retention time values. This degradation product was characterized by 1H-NMR and 13C-NMR spectroscopy as well as ion trap mass spectrometry. The results demonstrated that the method would have a great value when applied in quality control and stability studies for stiripentol. PMID:25371844

Darwish, Hany W.; Abdelhameed, Ali S.; Bakheit, Ahmed H.; Khalil, Nasr Y.; Al-Majed, Abdulrahman A.

2014-01-01

195

Stress Degradation Behavior of Abacavir Sulfate and Development of a Suitable Stability-Indicating UHPLC Method for the Determination of Abacavir, its Related Substances, and Degradation Products.  

PubMed

A novel, stability-indicating UHPLC method was developed for the quantitative determination of Abacavir sulfate, its related substances, and forced degradation impurities in bulk drugs. The chromatographic separation was achieved on a Waters Acquity BEH C(8), 50 mm × 2.1 mm, 1.7 ?m particle size column with a mobile containing a gradient mixture of solution A (0.10 % v/v o-phosphoric acid in water) and solution B (0.10% v/v o-phosphoric acid in methanol). The flow rate was set at 0.40 mL/min and the run time was 6.0 min. The drug substance was subjected to the stress studies of hydrolysis, oxidation, photolysis, and thermal degradation. Abacavir sulfate was found to degrade significantly under acidic hydrolysis and oxidative stress conditions. The formed degradation products were reported and were well-resolved from Abacavir and its related substances. The mass balance was found to be satisfactory in all of the stress conditions, thus proving the stability-indicating capability of the method. The developed UHPLC method was validated to be in agreement with ICH requirements and found to be rapid, accurate, precise, linear, specific, and suitable for the quantitative determination of related substances and degradants in the bulk drug samples of Abacavir sulfate. PMID:23264939

Vukkum, Pallavi; Deshpande, Girish R; Babu, J Moses; Muralikrishna, R; Jagu, Pavani

2012-12-01

196

A Validated Stability-Indicating RP-UPLC Method for Simultaneous Determination of Desloratadine and Sodium Benzoate in Oral Liquid Pharmaceutical Formulations.  

PubMed

A novel, sensitive and selective stability-indicating gradient reverse phase ultra performance liquid chromatographic method was developed and validated for the quantitative determination of desloratadine and sodium benzoate in pharmaceutical oral liquid formulation. The chromatographic separation was achieved on Acquity BEH C8 (100 mm × 2.1 mm) 1.7 ?m column by using mobile phase containing a gradient mixture of solvent A (0.05 M KH(2)PO(4) and 0.07 M triethylamine, pH 3.0) and B (50:25:25 v/v/v mixture of acetonitrile, methanol and water) at flow rate of 0.4 mL/min. Column temperature was maintained at 40°C and detection was carried out at a wavelength of 272 nm. The described method shows excellent linearity over a range of 0.254 ?g/mL to 76.194 ?g/mL for desloratadine and 1.006 ?g/mL to 301.67 ?g/mL for sodium benzoate. The correlation coefficient for desloratadine and sodium benzoate was more than 0.999. To establish stability-indicating capability of the method, drug product was subjected to the stress conditions of acid, base, oxidative, hydrolytic, thermal and photolytic degradation. The degradation products were well resolved from desloratadine and sodium benzoate. The developed method was validated as per international ICH guidelines with respect to specificity, linearity, LOD, LOQ, accuracy, precision and robustness. PMID:22396911

Kumar, Navneet; Sangeetha, Dhanaraj; Reddy, Pingili Sunil; Prakash, Lakkireddy

2012-01-01

197

A Validated Stability-Indicating RP-UPLC Method for Simultaneous Determination of Desloratadine and Sodium Benzoate in Oral Liquid Pharmaceutical Formulations  

PubMed Central

A novel, sensitive and selective stability-indicating gradient reverse phase ultra performance liquid chromatographic method was developed and validated for the quantitative determination of desloratadine and sodium benzoate in pharmaceutical oral liquid formulation. The chromatographic separation was achieved on Acquity BEH C8 (100 mm × 2.1 mm) 1.7 ?m column by using mobile phase containing a gradient mixture of solvent A (0.05 M KH2PO4 and 0.07 M triethylamine, pH 3.0) and B (50:25:25 v/v/v mixture of acetonitrile, methanol and water) at flow rate of 0.4 mL/min. Column temperature was maintained at 40°C and detection was carried out at a wavelength of 272 nm. The described method shows excellent linearity over a range of 0.254 ?g/mL to 76.194 ?g/mL for desloratadine and 1.006 ?g/mL to 301.67 ?g/mL for sodium benzoate. The correlation coefficient for desloratadine and sodium benzoate was more than 0.999. To establish stability-indicating capability of the method, drug product was subjected to the stress conditions of acid, base, oxidative, hydrolytic, thermal and photolytic degradation. The degradation products were well resolved from desloratadine and sodium benzoate. The developed method was validated as per international ICH guidelines with respect to specificity, linearity, LOD, LOQ, accuracy, precision and robustness. PMID:22396911

Kumar, Navneet; Sangeetha, Dhanaraj; Reddy, Pingili Sunil; Prakash, Lakkireddy

2012-01-01

198

A Rapid, Stability Indicating RP-UPLC Method for Simultaneous Determination of Ambroxol Hydrochloride, Cetirizine Hydrochloride and Antimicrobial Preservatives in Liquid Pharmaceutical Formulation.  

PubMed

A stability indicating reversed phase ultra performance liquid chromatography (RP-UPLC) method was developed for simultaneous determination of ambroxol hydrochloride (AMB), cetirizine hydrochloride (CTZ), methylparaben (MP) and propylparaben (PP) in liquid pharmaceutical formulation. The desired chromatographic separation was achieved on an Agilent Eclipse plus C18, 1.8 ?m (50 × 2.1 mm) column using gradient elution at 237 nm detector wavelength. The optimized mobile phase consists of a mixture of 0.01 M phosphate buffer and 0.1 % triethylamine as a solvent-A and acetonitrile as a solvent-B. The developed method separates AMB, CTZ, MP and PP in presence of twelve known impurities/degradation products and one unknown degradation product within 3.5 min. Stability indicating capability was established by forced degradation experiments and seperation of known and unknown degradation products. The lower limit of quantification was established for AMB, CTZ, MP and PP. The developed RP-UPLC method was validated according to the International Conference on Harmonization (ICH) guidelines. This validated method is applied for simultaneous estimation of AMB, CTZ, MP and PP in commercially available syrup samples. Further, the method can be extended for estimation of AMB, CTZ, MP, PP and levo-cetirizine (LCTZ) in various commercially available dosage forms. PMID:21886901

Trivedi, Rakshit Kanubhai; Patel, Mukesh C; Jadhav, Sushant B

2011-09-01

199

Validated Stability-indicating Reverse-phase Ultra-performance Liquid Chromatography Method for Simultaneous Determination of Sodium Methylparaben, Sodium Propylparaben and Ketorolac Tromethamine in Topical Dosage Forms.  

PubMed

A sensitive, fast, and stability-indicating isocratic reverse-phase ultra-performance liquid chromatography method was developed and validated for quantitative simultaneous determination of sodium methylparaben, sodium propylparaben and ketorolac tromethamine in topical dosage forms. Separation of all peaks was achieved by using acquity ethylene bridged hybrid C18 (50×2.1 mm, 1.7 ?) as stationary phase, mobile phase used was triethylamine buffer (pH 2.5):tetrahydrofuran:methanol (665:35:300, v/v/v) with isocratic mode at a flow rate of 0.40 ml/min. All component were detected at 252 nm with 10 min run time. The described method was found to be linear in the concentration range of 248-744 ?g/ml for ketorolac tromethamine, 20.8-62.4 ?g/ml for sodium methylparaben and 2.38-7.13 ?g/ml for sodium propylparaben with correlation coefficients more than 0.999. Method was validated in terms of specificity, linearity, accuracy, precision, solution stability, filter equivalency, and robustness as per International Conference on Harmonization guideline. Formulation was exposed to the stress conditions of peroxide, acid, base, thermal, and photolytic degradation and proven all components were well separated in the presence of degradants. PMID:24019569

Roy, C; Chakrabarty, J; Modi, P B

2013-03-01

200

Development and validation of stability indicating method for the quantitative determination of venlafaxine hydrochloride in extended release formulation using high performance liquid chromatography  

PubMed Central

Objective: Venlafaxine,hydrochloride is a structurally novel phenethyl bicyclic antidepressant, and is usually categorized as a serotonin–norepinephrine reuptake inhibitor (SNRI) but it has been referred to as a serotonin–norepinephrine–dopamine reuptake inhibitor. It inhibits the reuptake of dopamine. Venlafaxine HCL is widely prescribed in the form of sustained release formulations. In the current article we are reporting the development and validation of a fast and simple stability indicating, isocratic high performance liquid chromatographic (HPLC) method for the determination of venlafaxine hydrochloride in sustained release formulations. Materials and Methods: The quantitative determination of venlafaxine hydrochloride was performed on a Kromasil C18 analytical column (250 × 4.6 mm i.d., 5 ?m particle size) with 0.01 M phosphate buffer (pH 4.5): methanol (40: 60) as a mobile phase, at a flow rate of 1.0 ml/min. For HPLC methods, UV detection was made at 225 nm. Results: During method validation, parameters such as precision, linearity, accuracy, stability, limit of quantification and detection and specificity were evaluated, which remained within acceptable limits. Conclusions: The method has been successfully applied for the quantification and dissolution profiling of Venlafaxine HCL in sustained release formulation. The method presents a simple and reliable solution for the routine quantitative analysis of Venlafaxine HCL. PMID:21814426

Kaur, Jaspreet; Srinivasan, K. K.; Joseph, Alex; Gupta, Abhishek; Singh, Yogendra; Srinivas, Kona S.; Jain, Garima

2010-01-01

201

Stability Indicating LC Method for Rapid Determination of Related Substances of O-Desmethyl Venlafaxine in Active Pharmaceutical Ingredients and Pharmaceutical Formulations.  

PubMed

A simple, precise and accurate stability-indicating reversed phase-high performance liquid chromatography method was developed for the quantitative determination of O-desmethyl venlafaxine (ODV) and its related substances in active pharmaceutical ingredient and pharmaceutical formulation. The method was developed using YMC-pack ODS-A (150 × 4.6 mm, 3 ?m) column with mobile phase containing a gradient mixture of solvents A and B. Solvent A contained a mixture of buffer and acetonitrile in the ratio of 85:15 (v/v). The buffer consisted of 10 mM potassium dihydrogen phosphate and 2 mM 1-octane sulfonic acid sodium salt (pH adjusted to 6.0 by using diluted potassium hydroxide solution). Solvent B contained a mixture of water and acetonitrile in the ratio of 20:80 (v/v). The eluted compounds were monitored at 230 nm. ODV and its six impurities were well separated within 14 min run time. It was subjected under the stress conditions of oxidative, acid, base, water, thermal and photolytic degradation. It was sensitive towards acidic, basic, oxidative and water stress conditions, stable in photolytic and thermal degradation conditions. The degradation products were well resolved from main peak and its impurities, the mass balance in each case was >99.0%, proving the stability-indicating power of the method. The developed method was validated as per International Conference on Harmonization (ICH) guidelines with respect to its specificity, linearity (correlation coefficient >0.9996), limit of detection, limit of quantification, accuracy (recovery range 97.1-103.2%), precision (% relative standard deviation ?1.9%) and robustness. PMID:24474426

Rao, Karri Visweswara; Reddy, Kesareddy Padmaja; Kumar, Yelavarthi Ravindra

2014-11-01

202

A novel validated stability indicating high performance liquid chromatographic method for estimation of degradation behavior of ciprofloxacin and tinidazole in solid oral dosage  

PubMed Central

Objective: The objective of current investigation was to study the degradation behavior of Ciprofloxacin and Tinidazole. The study was performed as per International Conference on Harmonization recommended stress condition. A novel stability-indicating reverse phase HPLC method was developed for the determination of Ciprofloxacin and Tinidazole purity in the presence of its impurities and forced degradation products. This method is also capable to separate placebo peaks as well in pharmaceutical dosage forms. The solid oral dosage form was subjected to the stress conditions such as oxidative, acid, base hydrolysis, heat and photolytic degradation. Materials and Methods: The method was developed using Waters symmetry shield, Reverse Phase (RP) C18, 250mm x 4.6mm, 5? as a stationary phase. The mobile phase containing a gradient mixture of solvent A and B. 10mM phosphate buffer, adjusted pH 3.0 with phosphoric acid was used as a buffer. Buffer pH 3.0 was used as solvent A and buffer pH 3.0: Acetonitrile in the ratio of 20: 80 v/v were used as solvent B. The eluted compounds were monitored 278 nm (Ciprofloxacin), 317 nm (Tinidazole). The run time was 50 minute. Results: In the precision study the % RSD for the result of Ciprofloxacin, Tinidazole and its impurities was below 10%. The method was linear with the correlation coefficient greater than 0.997. The percentage recoveries were calculated and observed from 93.0% to 106.7%. The peak purity of Ciprofloxacin, Tinidazole peak had not shown any flag, thus proved the stability-indicating power of the method. Conclusion: The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness. PMID:24302838

Vaghela, Bhupendrasinh K.; Rao, Surendra Singh

2013-01-01

203

A novel and rapid validated stability-indicating UPLC method of related substances for dorzolamide hydrochloride and timolol maleate in ophthalmic dosage form.  

PubMed

A novel stability-indicating gradient reversed-phase ultra-performance liquid chromatographic (RP-UPLC) method was developed for the determination of purity of dorzolamide hydrochloride and timalol maleate in presence of their impurities, and forced degradation products and placebo. The method was developed using a Waters UPLC BEH C18, 100 × 2.1mm, 1.7 µm column with mobile phase containing a gradient mixture of solvents A and B. Phosphate buffer (0.04M), pH 2.6 was used as buffer. Buffer pH 2.6 was used as solvent A and Milli-Q water, methanol and acetonitrile in 200:300:600, v/v/v ratios were used as solvent B. The gradient program was set as 0/5, 8/8, 10/15, 16/45, 20/55, 24/80, 25/5 and 30/5. The eluted compound dorzolamide hydrochloride and its impurities were monitored at 254 nm, and timalol maleate and its impurities were monitored at 295 nm. The run time was 30 min, within which dorzolamide hydrochloride and its five impurities as well as timalol maleate and its three impurities were well separated, with resolution more than 2.0. Dorzolamide hydrochloride and timalol maleate were subjected to the stress conditions of oxidative, acid, base, photolytic and thermal degradation. The peak purity of dorzolamide hydrochloride, timalol maleate and their related compounds did not show any flag, thus proved the stability-indicating power of the method. The developed method was validated as per International Conference of Harmonization guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness. PMID:22562819

Sharma, Nitish; Rao, Surendra Singh; Reddy, A Malleswara

2012-10-01

204

The ICH guidance in practice: stress degradation studies on indinavir sulphate and development of a validated specific stability-indicating HPTLC assay method.  

PubMed

A sensitive, selective, precise and stability-indicating high-performance thin layer chromatography (HPTLC) method for analysis of indinavir sulphate both as a bulk drug and in formulations was developed and validated. The method employed TLC aluminium plates precoated with silica gel 60F-254 as the stationary phase. The solvent system consisted of carbon tetrachloride/chloroform/methanol/10% v/v ammonia (4:4.5:1.5:0.05, v/v/v/v). Densitometric analysis of indinavir sulphate was carried out in the absorbance mode at 260 nm. This system was found to give compact spots for indinavir sulphate (Rf value of 0.43 +/- 0.02, for six replicates). Indinavir sulphate was subjected to acid and alkali hydrolysis, oxidation, dry and wet heat treatment, and photo degradation. The drug undergoes degradation under acidic and basic conditions, oxidation, dry and wet heat treatment, and photo degradation. Also the degraded products were well resolved from the pure drug with significantly different Rf values. The method was validated for linearity, precision, robustness, limit of detection (LOD), limit of quantitation (LOQ), specificity and accuracy. Linearity was found to be in the range of 100-6000 ng/spot with significantly high value of correlation coefficient r2 = 0.997 +/- 0.64. The linear regression analysis data for the calibration plots showed good linear relationship with r2 = 0.999 +/- 0.002 in the working concentration range of 1000-6000 ng/spot. The LOD and LOQ were 40 and 120 ng/spot, respectively. Statistical analysis proves that the method is repeatable and specific for the estimation of the said drug. As the method could effectively separate the drug from its degradation products, it can be employed as a stability-indicating one. Moreover, the proposed HPTLC method was utilized to investigate the kinetics of acid degradation process. Arrhenius plot was constructed and activation energy was calculated. PMID:15337439

Kaul, Neeraj; Agrawal, Himani; Paradkar, A R; Mahadik, K R

2004-09-01

205

Development and validation of a stability indicative HPLC-PDA method for kaurenoic acid in spray dried extracts of Sphagneticola trilobata (L.) Pruski, Asteraceae.  

PubMed

A gradient stability indicative HPLC-UV method was developed and validated for assay of the marker kaurenoic acid (KA) in spray dried extract of Sphagneticola trilobata (L.) Pruski. The marker, and another unidentified polar component, were separated on a Luna Phenomenex C(18) column (250×4.6 mm, 5 ?m) with mobile phase composed of acetonitrile:acidified water pH 3.0 with phosphoric acid, in a gradient run of 40 min; at a flow rate of 1.0 mL min(-1), 35 °C, using wavelengths of 210 and 338 nm. The method was linear over a KA concentration range of 4.5-30.0 ?g mL(-1), without interference of the herbal matrix on the linearity of the method. The RSD% values for the intra- and inter-day precision studies were <2.0 and <8.0% for inter-laboratorial study. The method showed excellent KA recovery (99.0%). The LOQ value was found to be 1.13 ?g mL(-1) and the method proved to be robust for small, deliberate changes in temperature and pH of the mobile phase with RSD%<2.5% for the KA assay. A forced degradation study of S. trilobata dried extract was conducted under conditions of visible light (1.200.000 l×h(-1)) and UV (200 Whm(-2)) irradiation, acid (0.5 mol L(-1) HCl, 30 min), basic (1 mol L(-1) NaOH, 2 h) and oxidative (30% H(2)O(2), 4h) hydrolysis, in order to develop a gradient stability-indicating LC-UV method for KA quantification, the selected marker, and also to detect the major polar components of the extract, under investigation. The KA contents remaining after these stress conditions were 72.3, 70.0, 97.6, 65.8 and 87.0%, respectively. The alkaline conditions resulted in higher degradation for the unknown polar components of the extract, without interference of supplementary peaks at the retention time of the KA. This method can be used for the KA assay and qualitative analysis of polar components in stability study of spray dried extracts of S. trilobata, for subsequent use in the quality control of dosage forms. PMID:23158359

Fucina, Giovana; Block, Luciana Catia; Baccarin, Thaisa; Ribeiro, Thiago Ruiz Gutierrez; Quintão, Nara Lins Meira; Filho, Valdir Cechinel; Silva, Ruth Meri Lucinda; Bresolin, Tania Mari Bellé

2012-11-15

206

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

207

Longitudinal stability of social competence indicators in a Portuguese sample: Q-sort profiles of social competence, measures of social engagement, and peer sociometric acceptance.  

PubMed

This study examines the temporal stability (over 3 years) of individual differences in 3 domains relevant to preschool children's social competence: social engagement/motivation, profiles of behavior and personality attributes characteristic of socially competent young children, and peer acceptance. Each domain was measured with multiple indicators. Sociometric status categories (Asher & Dodge, 1986) and reciprocated friendships were derived from sociometric data. Composites for social competence domains were significantly associated across all time points. Within age-periods, social competence domains were associated with both sociometric and friendship status categories; however, neither sociometric status nor reciprocated friendships were stable over time. Nevertheless, analyses examining the social competence antecedents to reciprocated friendship at age-4 and age-5 suggested that more socially competent children in the prior year were more likely to have a reciprocated friendship in the current year. Popular and rejected sociometric status categories were also associated with social competence indicators in prior years, but this was most clearly seen at age-5. PMID:24015691

Santos, António J; Vaughn, Brian E; Peceguina, Inês; Daniel, João R

2014-03-01

208

NOVEL RP-HPLC METHOD DEVELOPMENT AND VALIDATION OF METFORMIN AND PIOGLITAZONE DRUGS IN PURE AND PHARMACEUTICAL DOSAGE FORMS  

E-print Network

The present investigation describes about a simple, economic, selective, accurate, precise reverse phase high performance liquid chromatographic method for the simultaneous estimation of metformin and pioglitazone in pure and pharmaceutical dosage forms. Metformin and pioglitazone were well separated using a HYPERSIL BDS C18column of dimension 250 × 4.6, 5µm and Mobile phase consisting of Phosphate buffer ( Pottasium dihydrogen phosphate) : Methanol (Adjusted with Ortho phosphoric acid to pH-4.5) in the ratio of 70:30v/v at the flow rate 1 ml/min and the detection was carried out at 240nm with PDA detector. The Retention time for Metformin and Pioglitazone were found to be 1.945, 3.595min respectively. The developed method was validated for recovery, specificity, precision, accuracy, linearity according to ICH guidelines. The method was successfully applied to Metformin, and Pioglitazone combination pharmaceutical dosage form.

Alekhya Pallapolu; Aneesha A

209

Optimized method for simultaneous determination of catechin, gallic acid, and methylxanthine compounds in chocolate using RP-HPLC  

Microsoft Academic Search

The simultaneous determination of catechins, gallic acid, and three methylxanthine compounds was determined in chocolate extract by reversed-phase HPLC. An isocratic HPLC procedure using Hypersil-ODS column with methanol three distilled water-formic acid (48.75:200.5:0.75, v\\/v\\/v) as a mobile phase was used and the HPLC profiles of 11 chocolate products were obtained. (-)- Epicatechin, (-)-epigallocatechin gallate, levels were very high whereas (+)-catechin,

Özlem Tokusoglu; Kemal M. Ünal

2002-01-01

210

Simultaneous Determination of Ofloxacin and Ornidazole in Solid Dosage Form by RP-HPLC and HPTLC Techniques.  

PubMed

The objective of this work was to develop and validate simple, rapid and accurate chromatographic methods for simultaneous determination of ofloxacin and ornidazole in solid dosage form. The first method was based on reversed phase high performance liquid chromatography, on Intersil C(18) column (250 mm, 4.6 i.d.), using acetonitrile:methanol: 0.025M phosphate buffer, pH 3.0 (30:10:60 % v/v/v) as the mobile phase, at a flow rate of 1 ml/min at ambient temperature. Quantification was achieved with UV detection at 318 nm over a concentration range of 2-40 µg/ml for ofloxacin and 5-100 µg/ml for ornidazole. The mean retention time of ofloxacin and ornidazole was found to be 4.04 min and 5.83 min, 6.77 min (isomers), respectively. The amount of ofloxacin and ornidazole estimated as percentage of label claimed was found to be 100.23 and 99.61%, with mean percent recoveries 100.20 and 100.93%, respectively. The second method was based on TLC separation of these drugs using silica gel 60F(254) aluminium sheets and dichloromethane:methanol:25% ammonia solution (9.5:1:3 drops v/v) as mobile phase. Detection was carried out at 318 nm over the concentration range of 20-100 ng/spot for ofloxacin and 50-250 ng/spot for ornidazole. The mean R(f) value of ofloxacin and ornidazole was found to be 0.16 and 0.56, 0.78 (isomers), respectively. The amount of ofloxacin and ornidazole estimated as percentage of label claimed was found to be 100.23 and 99.61% with mean percent recoveries 100.47 and 99.32%, respectively. Both these methods were found to be simple, precise, accurate, selective and rapid and could be successfully applied for the determination of pure laboratory prepared mixtures and tablets. PMID:21218068

Puranik, Manisha; Bhawsar, D V; Rathi, Prachi; Yeole, P G

2010-07-01

211

Determination of underivatized long chain fatty acids using RP-HPLC with capacitively coupled contactless conductivity detection.  

PubMed

A reversed-phase high-performance liquid chromatographic method with capacitively coupled contactless conductivity detector (C(4)D) has been developed for the separation and the simultaneous determination of five underivatized long chain fatty acids (FAs), namely myristic, palmitic, stearic, oleic, and linoleic acids. An isocratic elution mode using methanol/1mM sodium acetate (78:22, v/v) as mobile phase with a flow rate of 0.6 mL min(-1) was used. The separation was effected by using a Hypersil ODS C(18) analytical column (250 mm x 4.6 mm x 5 microm) and was operated at 45 degrees C. Calibration curves of the five FAs were well correlated (r(2)>0.999) within the range of 5- 200 microg mL(-1) for stearic acid, and 2-200 microg mL(-1) for the other FAs. The proposed method was tested on four vegetable oils, i.e., pumpkin, soybean, rice bran and palm olein oils; good agreement was found with the standard gas chromatographic (GC) method. The proposed method offers distinct advantages over the official GC method, especially in terms of simplicity, faster separation times and sensitivity. PMID:20188881

Makahleh, Ahmad; Saad, Bahruddin; Siang, Gan Hui; Saleh, Muhammad Idiris; Osman, Hasnah; Salleh, Baharuddin

2010-04-15

212

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

PubMed Central

Reversed-phase HPLC and UV spectrophotometric techniques using water as solvent have been developed and validated for the simultaneous determination of amoxicillin and cloxacillin in capsules. For both techniques, the linearity range of 60.073x2013;140.0 µg/mL was studied. The spectrophotometric data show that non-derivative techniques, such as absorbance ratio and compensation, and ratio spectra first-order derivative could be successfully used for the co-assay of amoxicillin and cloxacillin. Based on the statistical comparison of spectrophotometric and chromatographic data, the interchangeability between HPLC and UV spectrophotometric techniques has been suggested for the routine analysis. PMID:21264124

Giang, Do T; Hoang, Vu D

2010-01-01

213

Simultaneous RP-HPLC-DAD separation, and determination of flavonoids and phenolic acids in Plantago L. species.  

PubMed

A rapid reversed-phase (RP) high-performance liquid chromatography method was developed and applied for simultaneous separation, and determination of flavonoids and phenolic acids in eight Plantago L. taxa (P. altissima L., P. argentea Chaix, P. coronopus L., P. holosteum Scop. ssp. depauperata Pilger, P. holosteum ssp. holosteum, P. holosteum ssp. scopulorum (Degen) Horvati?, P. lagopus L., and P. maritima L.) growing in Croatia. Chromatographic separation was carried out on Zorbax Eclipse XDB-C18 using gradient elution with a H2 O (pH?2.5, adjusted with CF3 COOH) and MeCN mixture at 30°. The contents of analyzed phenolic compounds (% of the dry weight of the leaves, dw) varied among examined species: rutin (max. 0.024%, P. argentea), hyperoside (max. 0.020%, P. lagopus), quercitrin (max. 0.013%, P. holosteum ssp. holosteum), quercetin (max. 0.028%, P. holosteum ssp. scopulorum), chlorogenic acid (max. 0.115%, P. lagopus), and caffeic acid (max. 0.046%, P. coronopus). Isoquercitrin was detected only in P. argentea (0.020%), while isochlorogenic acid content was below limit of quantification in all investigated species. Multivariate analyses (UPGMA and PCA) showed significant differences in contents of investigated polyphenolic compounds between different Plantago taxa. Accordingly, investigated substances might be employed as chemotaxonomic markers in the study of the complex genus Plantago. PMID:23847075

Juriši? Grubeši?, Renata; Sre?nik, Goran; Kremer, Dario; Vukovi? Rodríguez, Jadranka; Nikoli?, Toni; Vladimir-Kneževi?, Sanda

2013-07-01

214

Simultaneous quantitative determination of cinnamaldehyde and methyl eugenol from stem bark of Cinnamomum zeylanicum Blume using RP-HPLC.  

PubMed

A simple, sensitive, and precise reversed-phase high performance liquid chromatographic (HPLC) method has been developed, validated and used for simultaneous quantitative determination of cinnamaldehyde and methyl eugenol from the methanolic extract of dried bark powder of Cinnamomum zeylanicum Blume (family Lauraceae). The ultrasonic extraction method was used for the extraction of these compounds. The reversed-phase HPLC analysis was carried out using a Intersil ODS-3V-C(18) (150 mm x 4.6 mm, 5 microm) column and a mobile phase comprising of methanol-acetonitrile-water in the volume ratio of 35:20:45, delivered at a flow rate of 1.0 cm(3)/min. The detection and quantitation of both the compounds was carried out at 221 nm. PMID:20056038

Gursale, Atish; Dighe, Vidya; Parekh, Guarang

2010-01-01

215

RP-HPLC Method Development and Validation for the Simultaneous Estimation of Ofloxacin and Tinidazole in Tablets  

Microsoft Academic Search

A simple Reverse phase liquid chromatographic method has been developed and subsequently validated for simultaneous determination of Ofloxacin and Tinidazole in combination. The separation was carried out using a mobile phase consisting of 0.5%v\\/v Triethylamine buffer of pH 3.0 and Acetonitrile in the ratio of 73: 27. The column used was Kromasil C8, 5µ, 15 cm × 4.6 mm id

J. Dharuman; M. Vasudevan; K. N. Somasekaran; B. Dhandapani; Prashant D. Ghode; M. Thiagarajan

216

RP-HPLC SEPARATION METHOD FOR INDIVIDUAL COMPONENTS OF POLYCAP IN PRESENCE OF THEIR DEGRADATION\\/INTERACTION PRODUCTS  

Microsoft Academic Search

Polypill is a fixed dose combination, used as a single daily pill to achieve a large effect in preventing cardiovascular disease with minimal adverse effects. In the present study, gradient LC method was developed for simultaneous determination of the Polycap, that is, Atenolol, Hydrochlorothiazide, Aspirin, Ramipril, and Simvastatin, in presence of their major interaction\\/degradation products. The individual drug components and

Satheesh Kumar Shetty; Roshan M. Borkar; Prashant S. Devrukhakar; K. V. Surendranath; P. Radhakrishnanand; J. Satish; Nalini Shastri; Johnson Jogul; Upendra Mani Tripathi

2012-01-01

217

Optimization and Validation of RP-HPLC-UV/Vis Method for Determination Phenolic Compounds in Several Personal Care Products  

PubMed Central

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

Akkbik, Mohammed; Assim, Zaini Bin; Ahmad, Fasihuddin Badruddin

2011-01-01

218

Collapse of the sea surface stability during the Miocene to Quartenary in the Western Pacific Ocean, indicated by Discoaster abundance and Coccolith size change  

NASA Astrophysics Data System (ADS)

We describe in detail the middle Miocene to Pleistocene paleoceanography of the Western Pacific Ocean based on calcareous nannofossils. Abundantly occurrence of discoasters, which indicates the stable sea surface stratification and the development of thermo- and nutri-cline, are found in the interval from NN2 to NN4 zones of the early Miocene. The relative abundance of discoaster is decreased in the NN4-5 zone and it changed to very rare above NN10 (B in Fig.1). These characteristics are found in both Sites 805 and 782. Focusing to the mean size of Reticulofenestra species, it decreased at NN4-5 zone (A in Fig 2), and lower part of NN11 (B in Fig. 2). The presence of larger size Reticulofenestra species also show the oligotrophic conditions of sea surface with thermocline. On the basis of these results, the collapse of the stability of the sea surface stratification in the Western Pacific Ocean progressed throughout the Miocene to Quaternary. As the results, nutrient conditions of sea surface in these area were changed in steps from oligotrophic to eutrophic conditions at NN4-5 and lower part of NN11 (A and B in Fig. 2). These datum related to collapse of sea surface conditions, is cleary correlated to the timing of the end of Mid-Miocene Climatic Optimum (A) and the intensify of the Asian Monsoon (B; Fig. 2).

Sato, T.; Pratiwi, S. D.; Farida, M.

2013-12-01

219

Development of a stability-indicating HPLC method of Etifoxine with characterization of degradation products by LC-MS/TOF, (1)H and (13)C NMR.  

PubMed

This paper describes a new LC-MS/TOF method for the degradation products determination when Etifoxine (ETI) is submitted to different stress conditions. Chromatography is performed by using Kromasil C18 column (250mm×4.6mm, 5?m particle size). The selected mobile phase consists of formate buffer 0.02M, pH 3 and methanol (70/30, v/v). ETI is submitted to oxidative, acidic, basic, hydrolytic, thermal and UV light degradations. Detection is made at 254nm by photodiode array detector and mass spectrometry. A number of degradation products (DPs) called DPA, DPB, DPC and DPD are found depending on the stress; DPA with heat, DPA and DPB in acidic media or under UV-light; DPA, DPB and DPC under basic stress; DPA, DPB, DPC and DPD with oxidation. LC-MS/TOF is used to characterize the four DPs of ETI resulting from different stress conditions. (1)H and (13)C NMR are used to confirm the DP structures. The ETI fragmentation pathway is proposed. The method is validated with reference to International Conference on Harmonization guidelines and ETI are selectively determined in presence of its DPs, demonstrating its stability-indicating nature. Finally, for the validation step, specificity, linearity, accuracy and precision are determined for ETI and its DPs. PMID:25117950

Djabrouhou, Nadia; Guermouche, Moulay-Hassane

2014-11-01

220

Validated Stability-indicating High-performance Liquid Chromatographic Method for Estimation of Degradation Behaviour of Eberconazole Nitrate and Mometasone Furoate in Cream Formulation  

PubMed Central

The objective of current investigation was to study the degradation behaviour of eberconazole nitrate and mometasone furoate under different International Conference on harmonisation recommended stress condition using reverse phase high performance liquid chromatographic method and to establish validated stability-indicating high performance liquid chromatographic method to determine purity of eberconazole nitrate and mometasone furoate in presence of its impurities, forced degradation products and placebo in pharmaceutical dosage forms. The method was developed using Hypersil BDS, C18, 150?4.6 mm, 5 ? as stationary phase with mobile phase containing a gradient mixture of solvent A and B. 0.01 M phosphate buffer with 0.1% triethyl amine, adjusted pH 7.0 with phosphoric acid was used as buffer. Buffer pH 7.0 was used as solvent A and methanol:acetonitrile in 150:850 v/v ratios were used as solvent B. The eluted compounds were monitored at 240 nm. The run time was 50 min. The developed method was validated as per international conference on harmonization guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness. PMID:23901164

Sharma, N.; Rao, S. S.; Vaghela, B.

2013-01-01

221

A Novel, Validated Stability-Indicating UPLC Method for the Estimation of Lansoprazole and its Impurities in Bulk Drug and Pharmaceutical Dosage Forms.  

PubMed

A novel, reversed-phase ultra-performance liquid chromatographic method was developed and validated for the determination of the assay and related substances of Lansoprazole (LAN) in bulk drug and capsule dosage forms. The related substances include degradation and process-related impurities. The method was developed using the Waters Acquity BEH C18 column and gradient program with mobile phase A as a pH 7.0 phosphate buffer and methanol in the ratio of 90: 10 (v/v), and mobile phase B as methanol and acetonitrile in the ratio of 50:50 (v/v). Lansoprazole and its impurities were monitored at 285 nm. Lansoprazole was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal, humidity, and photolytic degradation and found to degrade significantly under acid and oxidative stress conditions. The degradation products were well-resolved from the main peak and its impurities, proving the stability-indicating power of the method. The performance of the method was validated according to the present ICH guidelines for specificity, limit of detection, limit of quantification, linearity, accuracy, precision, ruggedness, and robustness. PMID:23641337

Rao, Papanaboina Venkata; Kumar, Morrisetty Nagendra; Kumar, Maram Ravi

2013-03-01

222

Novel Validated Stability-Indicating UPLC Method for the Estimation of Naproxen and its Impurities in Bulk Drugs and Pharmaceutical Dosage Form.  

PubMed

A novel, reversed-phase ultra-performance liquid chromatographic method was developed and validated for the determination of related substances in Naproxen (NAP) bulk drugs and dosage forms. The related substances included degradation and process-related impurities. The method was developed using the Waters Acquity BEH C18 column using the gradient program with mobile phase A of a pH 7.0 phosphate buffer and methanol in the ratio of 90: 10 (v/v) and mobile phase B as methanol and acetonitrile in the ratio of 50:50 (v/v). Naproxen and its impurities were monitored at 260 nm. Naproxen was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal, humidity, and photolytic degradations. The degradation products were well-resolved from the main peak and its impurities, proving the stability-indicating power of the method. The performance of the method was validated according to the present ICH guidelines for specificity, limit of detection, limit of quantification, linearity, accuracy, precision, ruggedness, and robustness. PMID:23264943

Venkatarao, Papanaboina; Nagendra Kumar, Morrisetty; Ravi Kumar, Maram

2012-12-01

223

Validated Stability-indicating High-performance Liquid Chromatographic Method for Estimation of Degradation Behaviour of Eberconazole Nitrate and Mometasone Furoate in Cream Formulation.  

PubMed

The objective of current investigation was to study the degradation behaviour of eberconazole nitrate and mometasone furoate under different International Conference on harmonisation recommended stress condition using reverse phase high performance liquid chromatographic method and to establish validated stability-indicating high performance liquid chromatographic method to determine purity of eberconazole nitrate and mometasone furoate in presence of its impurities, forced degradation products and placebo in pharmaceutical dosage forms. The method was developed using Hypersil BDS, C18, 150?4.6 mm, 5 ? as stationary phase with mobile phase containing a gradient mixture of solvent A and B. 0.01 M phosphate buffer with 0.1% triethyl amine, adjusted pH 7.0 with phosphoric acid was used as buffer. Buffer pH 7.0 was used as solvent A and methanol:acetonitrile in 150:850 v/v ratios were used as solvent B. The eluted compounds were monitored at 240 nm. The run time was 50 min. The developed method was validated as per international conference on harmonization guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness. PMID:23901164

Sharma, N; Rao, S S; Vaghela, B

2013-01-01

224

Stability-indicating high performance liquid chromatographic determination of raubasine in its binary mixture with kinetic study of raubasine acid degradation.  

PubMed

Stability-indicative determination of raubasine (RAB) in the presence of its degradate and its binary mixture with almitrine dismesylate (ALM) was investigated. The degradation product had been isolated, via acid-degradation, characterized and confirmed. Selective quantification of RAB and ALM in bulk form, pharmaceutical formulations and/or in the presence of RAB degradate was demonstrated. The analytical technique adopted for quantification was high performance liquid chromatography (HPLC). Separation was performed using a ZORBAX ODS column with a mobile phase consisting of acetonitrile+phosphate buffer pH 3.4 80:20 (v/v) with UV detection at 254 nm. The method showed high sensitivity with good linearity over the concentration range of 5-120 and 5-60 ?g mL(-1) for RAB and ALM respectively. The HPLC method was used to study the kinetics of RAB acid degradation that was found to follow a first-order reaction. The activation energy could be estimated from the Arrhenius plot and it was found to be 18.152 kcal mol(-1). PMID:21147311

El-Sayed, Mohammad A

2011-01-15

225

A Single Gradient Stability-Indicating Reversed-Phase LC Method for the Estimation of Impurities in Omeprazole and Domperidone Capsules  

PubMed Central

A gradient reversed-phase liquid chromatographic (RP-LC) method was developed for the quantitative estimation of impurities in the pharmaceutical dosage form of Omeprazole and Domperidone capsules. The developed method is a stability-indicating test method for the estimation of impurities generated during the formulation and storage of Omeprazole and Domperidone capsules. The chromatographic separation was achieved on a column packed with octadecyl silane, having a column length of 250 mm and diameter of 4.6 mm with a particle size of 5 ?m, and by following a gradient program using a combination of a monobasic potassium phosphate buffer (0.05M) and acetonitrile. Since the spectral properties were similar, both compounds’ individual impurities were estimated at 285 nm. Forced degradation studies were performed on Omeprazole pellets (enteric coated) and Domperidone pellets (SR coated) encapsulated in size ‘1’ hard gelatin capsules. Omeprazole and Domperidone were degraded using acid hydrolysis (0.1 N hydrochloric acid), base (0.1 N sodium hydroxide), oxidation (50% hydrogen peroxide), heat (105 °C), and UV light (254 nm). The established method was validated and found to be linear, accurate, precise, specific, robust, and rugged. PMID:23833712

Seshadri, Raja Kumar; Raghavaraju, Thummala Veera; Chakravarthy, Ivon Elisha

2013-01-01

226

Water soluble inner aqueous phase markers as indicators of the encapsulation properties of water-in-oil-in-water emulsions stabilized with sodium caseinate  

Microsoft Academic Search

The aim of this study was to evaluate the suitability of Methylene Blue (MB) and Vitamin B12 (Vit-B12) as water soluble inner aqueous phase (W1) markers for measuring the encapsulation efficiency and stability of water-in-oil-in-water (W1\\/O\\/W2) double emulsions stabilized by sodium caseinate (NaCN). The encapsulation efficiency and stability were determined by centrifugation of the double emulsion to separate the cream

Jonathan O' Regan; Daniel M. Mulvihill

2009-01-01

227

Stress Degradation Behavior of Atorvastatin Calcium and Development of a Suitable Stability-Indicating LC Method for the Determination of Atorvastatin, its Related Impurities, and its Degradation Products.  

PubMed

A rapid, reversed-phase liquid chromatographic method was developed for the quantitative determination of Atorvastatin calcium, its related substances (12 impurities), and degradation impurities in bulk drugs. The chromatographic separation was achieved on a Zorbax Bonus-RP column by employing a gradient elution with water-acetonitrile-trifluoroacetic acid as the mobile phase in a shorter run time of 25 min. The flow rate was 1.0 mL/min and the detection wavelength was 245 nm. The drug substance was subjected to stress studies such as hydrolysis, oxidation, photolysis, and thermal degradation, and considerable degradation was observed in acidic hydrolysis, oxidative, thermal, and photolytic stress conditions. The formed degradation products were reported and were well-resolved from the Atorvastatin and its related substances. The stressed samples were quantified against a qualified reference standard and the mass balance was found to be close to 99.5% (w/w) when the response of the degradant was considered to be equal to the analyte (i.e. Atorvastatin), which demonstrates the stability-indicating capability of the method. The method was validated in agreement with ICH requirements. The method developed here was single and shorter (25 min method for the determination of all 12 related impurities of Atorvastatin and its degradation products), with clearly better resolution and higher sensitivity than the European (85 min method for the determination of six impurities) and United States pharmacopeia (115 min and 55 min, two different methods for the determination of six related substances). PMID:23641331

Vukkum, Pallavi; Moses Babu, J; Muralikrishna, R

2013-03-01

228

Development of validated stability-indicating chromatographic method for the determination of fexofenadine hydrochloride and its related impurities in pharmaceutical tablets  

PubMed Central

A simple reversed phase high performance liquid chromatographic method with diode array detector (HPLC-DAD) has been developed and subsequently validated for the determination of fexofenadine hydrochloride (FEX) and its related compounds; keto fexofenadine (Impurity A), meta isomer of fexofenadine (Impurity B), methyl ester of fexofenadine (Impurity C) in addition to the methyl ester of ketofexofenadine (Impurity D). The separation was based on the use of a Hypersil BDS C-18 analytical column (250 × 4.6 mm, i.d., 5 ?m). The mobile phase consisted of a mixture of phosphate buffer containing 0.1 gm% of 1-octane sulphonic acid sodium salt monohydrate and 1% (v/v) of triethylamine, pH 2.7 and methanol (60:40, v/v). The separation was carried out at ambient temperature with a flow rate of 1.5 ml/min. Quantitation was achieved with UV detection at 215 nm using lisinopril as internal standard, with linear calibration curves at concentration ranges 0.1-50 ?g/ml for FEX and its related compounds. The optimized conditions were used to develop a stability-indicating HPLC-DAD method for the quantitative determination of FEX and its related compounds in tablet dosage forms. The drugs were subjected to oxidation, hydrolysis, photolysis and heat to apply stress conditions. Complete separation was achieved for the parent compounds and all degradation products. The method was validated according to ICH guidelines in terms of accuracy, precision, robustness, limits of detection and quantitation and other aspects of analytical validation. PMID:22136482

2011-01-01

229

Simultaneous determination of some water-soluble vitamins and preservatives in multivitamin syrup by validated stability-indicating high-performance liquid chromatography method.  

PubMed

HPLC stability-indicating method has been developed for the simultaneous determination of some water-soluble vitamins (ascorbic acid, thiamine hydrochloride, riboflavin-5'-phosphate sodium, pyridoxine hydrochloride, nicotinamide, D(+)-panthenol) and two preservatives (methylparaben and sodium benzoate) in multivitamin syrup preparation. Water-soluble vitamins, preservatives and their degradants were separated on Zorbax SB-Aq (C(18)) (250 mm x 4.6 mm, 5 microm) column at an ambient temperature. Combined isocratic and gradient elution was performed with a mobile phase consisting of 0.0125 M hexane-1-sulfonic acid sodium salt in 0.1% (m/v) o-phosphoric acid, pH 2.4-2.5 (solvent A) and acetonitrile (solvent B) at the flow-rate 1 ml min(-1). Starting with solvent A an isocratic elution was performed for 15 min, then the composition was changed to 85% of A and 15% of B during the next 20 min and it was constant for 5 min, then the composition was changed to 70% of A and 30% of B during next 15 min and it was constant for 5 min and finally was changed to 100% of A as at the beginning of the elution. Detection was performed with diode array detector at 210, 230 and 254 nm. Multivitamin syrup preparation was subjected to stress testing (forced degradation) in order to demonstrate that degradants from the vitamins, preservatives and/or product excipients do not interfere with the quantification of vitamins and preservatives. Typical validation characteristics: selectivity, accuracy, precision, linearity, range, limit of quantification and limit of detection were evaluated for vitamins and preservatives. PMID:18644604

Vidovi?, Stojanka; Stojanovi?, Biljana; Veljkovi?, Jelena; Prazi?-Arsi?, Ljiljana; Rogli?, Goran; Manojlovi?, Dragan

2008-08-22

230

Selective and stability-indicating methods for the simultaneous determination of mexiletine hydrochloride and/or its related substance: 2,6-dimethylphenol.  

PubMed

Four simple, rapid, sensitive, and selective analytical procedures were developed for determination of mexiletine hydrochloride (MX) and/or its related substance: 2,6-dimethylphenol (DMP). The latter is a synthetic impurity for which a maximum pharmacopeial limit is defined. The first method depends on derivative-ratio spectrophotometry, for which the first-derivative signals of the ratio spectra at 259 nm (Deltalambda = 3 nm) are selected for the determination of MX. The second method is based on the spectrofluorometric measurement of MX in alkaline solution in the presence of 15 mM sodium dodecyl sulfate micellar medium at 292 nm (lambdaEx 260 nm). The third method is based on liquid chromatographic (LC) separation of MX and DMP on an RP-C8 column with a mobile phase consisting of 50 mM Na2HPO4-acetonitrile (60 + 40, adjusted to pH 2.4), and quantification of the analytes is achieved with UV detection at 212 nm based on peak area. The fourth method uses the coupling reaction of DMP with 2,6-dibromo-quinone-4-chlorimide (DBQC) in borate buffer to form an intensely colored product that was spectrophotometrically measured using first-derivative amplitudes at 670 nm (Deltalambda = 6 nm) for the determination of DMP. Different variables affecting each method were carefully investigated and optimized. The reliability and analytical performance of the proposed methods, including linearity, range, precision, accuracy, and detection and quantitation limits, were statistically validated. The first 3 methods were successfully applied for the stability-indicating determination of MX in laboratory-prepared mixtures with DMP, as well as for the determination of MX in capsules. Also, the LC and the DBQC spectrophotometric methods permitted the selective determination of DMP in the presence of a large excess of the parent drug at or near the pharmacopeial limit (0.1-1%). PMID:18727529

Belal, Tarek S; Haggag, Rim S; Shaalan, Rasha A

2008-01-01

231

Gradient HPLC-diode array detector stability-indicating determination of lidocaine hydrochloride and cetylpyridinium chloride in two combined oral gel dosage forms.  

PubMed

A simple, rapid, and selective HPLC-diode array detector method was developed for the simultaneous determination of lidocaine hydrochloride (LD) and cetylpyridinium chloride (CPC) in two combined pharmaceutical formulations. Effective chromatographic separation was achieved on a Zorbax SB-C8 (4.6 x 250 mm, 5 microm particle size) column with gradient elution using a mobile phase composed of 0.05 M phosphoric acid and acetonitrile. The gradient elution started with 25% (v/v) acetonitrile, ramped up linearly to 85% in 5 min, and then was constant until the end of the run. The mobile phase was pumped at a flow rate of 1.2 mL/min. The multiple wavelength detector was set at 214 and 258 nm, and quantification of the analytes was based on measuring their peak areas. The retention times for LD and CPC were about 3.4 and 7.3 min, respectively. The reliability and analytical performance of the proposed HPLC procedure were statistically validated with respect to linearity, range, precision, accuracy, selectivity, robustness, LOD, and LOQ. Calibration curves were linear in the range of 5-200 and 10-400 microg/mL for LD and CPC, respectively, with correlation coefficients > 0.999. The proposed method was proven to be stability-indicating by the resolution of the two analytes from the related substance and potential impurity (2,6-dimethylaniline) as well as from forced-degradation products. The validated HPLC method was extended to the analysis of LD and CPC in two combined oral gel preparations for which the two analytes were successfully resolved from the pharmaceutical adjuvants and quantified with recoveries not less than 97.9%. PMID:21563684

Belal, Tarek S; Shaalan, Rasha A; Haggag, Rim S

2011-01-01

232

Rapid Simultaneous Determination of Telmisartan, Amlodipine Besylate and Hydrochlorothiazide in a Combined Poly Pill Dosage Form by Stability-Indicating Ultra Performance Liquid Chromatography  

PubMed Central

A simple, precise and rapid stability-indicating ultra-performance liquid chromatography (UPLC) method is developed for the simultaneous quantitative determination of Telmisartan, Amlodipine besylate and Hydrochlorothiazide from their innovative poly pill combination drug product in the presence of degradation products. It involves a 100 mm x 2.1 mm, 1.7 ?m C-18 column. The separation is achieved on a simple gradient method. The mobile phase A contains a mixture of sodium perchlorate buffer pH 3.2 (0.053M): acetonitrile in the ratio 90:10, v/v, and mobile B contains a mixture of sodium perchlorate buffer pH 3.2 (0.053M): acetonitrile in the ratio 20:80, v/v. The flow rate is 0.6 mL min?1 and the column temperature is maintained at 55°C.The gradient program (T/%B) is set as 0/5, 1.2/5, 1.6/40, 4/40, 4.1/5 and 4.5/5. The detector wavelength is 271 nm for Hydrochlorothiazide and Telmisartan and 237 nm for Amlodipine. The retention times of Telmisartan, Amlodipine, and Hydrochlorothiazide are 3.6 minutes, 3.2 minutes and 0.9 minutes; respectively. The total runtime for the separation of the three active compounds and their degradation products is 4.5 minutes. The described method is validated with respect to system suitability, specificity, linearity, precision and accuracy. The precision of the assay method is evaluated by carrying out six independent assays of T, A and H (0.032 mg mL?1 of T, 0.004 mg mL?1 of A, 0.01 mg mL?1 of H). The accuracy of the method is evaluated in triplicate at three concentration levels, i.e. 50%, 100% and 150% of target test concentration (0.64 mg mL?1 of T, 0.08 mg mL?1 of A, 0.2 mg mL?1 of H). The described method is linear over the range, 16 to 48 ?g mL?1 for T, 2 to 6 ?g mL?1A and 5 to 15 ?g mL?1 for H. The method is fast and suitable for high-throughput analysis allowing the analysis of about 250 samples per working day. PMID:21617773

Nalwade, Santaji; Ranga Reddy, Vangala; Durga Rao, Dantu; Koteswara Rao, Inabathina

2011-01-01

233

Investigation of folic acid stability in fortified instant noodles by use of capillary electrophoresis and reversed-phase high performance liquid chromatography.  

PubMed

A single enzyme treatment with alpha-amylase, prior to the quantification of added folic acid (FA) in fortified instant fried Asian noodles with analysis performed by capillary zone electrophoresis (CZE) and reversed-phase high performance liquid chromatography (RP-HPLC) with UV detection, is described. The method was validated and optimized for capillary electrophoresis (CE) with separation achieved using a 8 mM phosphate-12 mM borate run buffer with 5% MeOH at pH 9.5. FA was well separated from matrix components with nicotinic acid (NA) employed as an internal standard. In a comparative study, separation of FA was performed using HPLC with a mobile phase consisting of 27% MeOH (v/v) in aqueous potassium phosphate buffer (3.5 mM KH(2)PO(4) and 3.2 mM K(2)HPO(4)), pH 8.5, and containing 5 mM tetrabutylammonium dihydrogen phosphate as an ion-pairing agent. For both methods, excellent results were obtained for various analytical parameters including linearity, accuracy and precision. The limit of detection was calculated to be 2.2 mg/L for CE without sample stacking and 0.10 mg/L with high performance liquid chromatography (HPLC). Sample extraction involved homogenization and enzymatic extraction with alpha-amylase. Results indicated that FA was stable during four main stages of instant fried noodle manufacturing (dough crumbs, cut sheets, steaming and frying). PMID:18930464

Hau Fung Cheung, Rodney; Morrison, Paul D; Small, Darryl M; Marriott, Philip J

2008-12-01

234

Stabilization of insulin against agitation-induced aggregation by the GMO cubic phase gel.  

PubMed

The main objective of the study was to evaluate if the liquid crystalline cubic phase gel of glyceryl monooleate (GMO) protects insulin from agitation induced aggregation. The aggregation of Humulin(R), Regular Iletin I(R) and Regular Iletin II(R), in cubic phase GMO gels at 30 U/g of gel was compared with that in PBS at 100 oscillations/min at 37 degrees C using optical density at 600 nm. The effect of agitation on the secondary structure of insulin in solution and in the gels was determined with circular dichroism (CD) spectroscopy, and the time course of aggregation was also followed by HPLC. A sigmoidal increase in optical density of solution with time indicated formation of increasing amounts of insoluble insulin aggregates. However, in the gels, optical density values stayed at, or around, the initial optical density value, comparable with that of a blank gel suggesting that insulin had not aggregated in the gel. CD spectroscopy of the soluble insulin showed a total loss of native conformation upon aggregation of insulin in solution. In contrast, CD spectra of insulin in the gel were unaltered suggesting protection from aggregation during agitation. Furthermore, agitation of insulin in gels for a duration as long as 2 months at 37 degrees C, had very little adverse effect on the native conformation of insulin, as indicated by the lack of a significant change in its CD spectrum. Therefore, the cubic phase gel was indeed able to protect insulin from agitation-induced aggregation and subsequent precipitation. Although the majority of insulin in solution appeared to have aggregated and precipitated after 8 days by UV and CD spectroscopy, RP-HPLC results indicated the presence of some soluble aggregates of insulin. In summary, the liquid crystalline cubic phase gel of GMO protects peptides, like insulin, from agitation-induced aggregation. PMID:10556740

Sadhale, Y; Shah, J C

1999-11-25

235

Study of forced degradation behavior of Eletriptan hydrobromide by LC and LC–MS and development of stability-indicating method  

Microsoft Academic Search

The objective of the present study was to report the stability profile of novel antimigrain drug Eletriptan hydrobromide based on the information obtained from forced degradation studies. The drug was subjected to acid (0.1–1molL?1 HCl), neutral and base (0.1–1molL?1 NaOH) hydrolysis and to oxidative decomposition (3–15% (v\\/v) H2O2). Photolysis and thermo degradation at 75°C were carried out in methanol solution

Biljana Joci?; Mira Ze?evi?; Ljiljana Živanovi?; Ana Proti?; Milka Jadranin; Vlatka Vajs

2009-01-01

236

Florfenicol broad-spectrum antibiotic developed veterinary application oral concentrate intended dilution drinking water. drug product dosed via drinking water farm setting number variables including pH chlorine content hardness water dilution container material affect stability leading decrease drug potency. stability florfenicol after dilution Florfenicol Drinking Water Concentrate Oral Solution 23 mg/mL drinking water studied. stability-indicating validated liquid chromatographic method evaluate florfenicol stability 25 degrees 5 10 24 h after dilution. results indicate florfenicol stable under range simulated field conditions including pipe materials conditions hard soft chlorinated nonchlorinated water low high pH. Significant degradation ( 10%) observed only isolated combinations Stability florfenicol drinking water Hayes JM Eichman J Katz T Gilewicz R  

EPA Pesticide Factsheets

Search instead for Florfenicol broad-spectrum antibiotic developed veterinary application oral concentrate intended dilution drinking water. drug product dosed via drinking water farm setting number variables including pH chlorine content hardness water dilution container material affect stability leading decrease drug potency. stability florfenicol after dilution Florfenicol Drinking Water Concentrate Oral Solution 23 mg/mL drinking water studied. stability-indicating validated liquid chromatographic method evaluate florfenicol stability 25 degrees 5 10 24 h after dilution. results indicate florfenicol stable under range simulated field conditions including pipe materials conditions hard soft chlorinated nonchlorinated water low high pH. Significant degradation ( 10%) observed only isolated combinations Stability florfenicol drinking water Hayes JM Eichman J Katz T Gilewicz R ?

237

A Novel Approach to the Surgical Treatment of Lumbar Disc Herniations: Indications of Simple Discectomy and Posterior Transpedicular Dynamic Stabilization Based on Carragee Classification  

PubMed Central

Surgery of lumbar disc herniation is still a problem since Mixter and Barr. Main trouble is dissatisfaction after the operation. Today there is a debate on surgical or conservative treatment despite spending great effort to provide patients with satisfaction. The main problem is segmental instability, and the minimally invasive approach via microscope or endoscope is not necessarily appropriate solution for all cases. Microsurgery or endoscopy would be appropriate for the treatment of Carragee type I and type III herniations. On the other hand in Carragee type II and type IV herniations that are prone to develop recurrent disc herniation and segmental instability, the minimal invasive techniques might be insufficient to achieve satisfactory results. The posterior transpedicular dynamic stabilization method might be a good solution to prevent or diminish the recurrent disc herniation and development of segmental instability. In this study we present our experience in the surgical treatment of disc herniations. PMID:23653862

Ozer, A. F.; Keskin, F.; Oktenoglu, T.; Suzer, T.; Ataker, Y.; Gomleksiz, C.; Sasani, M.

2013-01-01

238

Study of forced degradation behavior of eletriptan hydrobromide by LC and LC-MS and development of stability-indicating method.  

PubMed

The objective of the present study was to report the stability profile of novel antimigrain drug Eletriptan hydrobromide based on the information obtained from forced degradation studies. The drug was subjected to acid (0.1-1 mol L(-1) HCl), neutral and base (0.1-1 mol L(-1) NaOH) hydrolysis and to oxidative decomposition (3-15% (v/v) H(2)O(2)). Photolysis and thermo degradation at 75 degrees C were carried out in methanol solution and in solid state with both Eletriptan hydrobromide bulk drug and the tablet formulation. The products formed under different stress conditions were investigated by LC and LC-MS. The experimental conditions for LC were chosen by employing experimental design and multicriteria decision making methodology. These powerful tools enabled the accomplishment of satisfactory resolution with the shortest possible analysis time. Analytes were separated on a C(18) column (XTerra, 150 mm x 3.9 mm, 5 microm) with the mobile phase composed of methanol-water solution of TEA (pH 6.52, 1%, v/v) (30:70, v/v) pumped at 1 mL min(-1) flow rate. The column temperature was set at 50 degrees C and the detection at 225 nm using DAD detector. The LC method was suitably modified for LC-MS analysis which was further used to characterize the arisen degradation products. The possible degradation pathway was outlined based on the results. The drug appeared to be instable towards every stress condition but oxidation. The stability was not jeopardized even under more exaggerated conditions such as increased temperature of the solutions to 75 degrees C, increased strength of acid/alkali solutions and prolonged testing period. Validation of the LC-DAD method was carried out in accordance with ICH guideline. The method met all required criteria and was applied when testing the commercially available tablets. PMID:19250786

Joci?, Biljana; Zecevi?, Mira; Zivanovi?, Ljiljana; Proti?, Ana; Jadranin, Milka; Vajs, Vlatka

2009-11-01

239

Stability-indicating validation of acitretin and isoacitretin in human plasma by LC-ESI-MS/MS bioanalytical method and its application to pharmacokinetic analysis.  

PubMed

LC- ESI- MS/MS simultaneous bioanalytical method was developed to determine acitretin and its metabolite isoacitretin in human plasma using acitretin-d3 used as the internal standard for both analytes. The compounds were extracted using protein precipitation coupled with liquid-liquid extraction with flash freezing technique. Negative mass transitions (m/z) of acitretin, isoacitretin and acitretin-d3 were detected in multiple reactions monitoring (MRM) mode at 325.4 ? 266.3, 325.2 ? 266.1 and 328.3 ? 266.3, respectively, with a turbo ion spray interface. The chromatographic separation was achieved on an Ascentis-RP amide column (4.6 × 150 mm, 5 µm) with mobile phase delivered in isocratic mode. The method was validated over a concentration range of 1.025-753.217 ng/mL for acitretin and 0.394-289.234 ng/mL for isoacitretin with a limit of quantification of 1.025 and 0.394 ng/mL. The intra-day and inter-day precisions were below 8.1% for acitretin and below 13.8% for isoacitretin, while accuracy was within ±7.0 and ±10.6% respectively. For the first time, the best possible conditions for plasma stability of acitretin and isoacitretin are presented and discussed with application to clinical samples. PMID:20845366

Kumar, Ajay; Monif, Tausif; Khuroo, Arshad; Sasmal, Dinakar; Goswami, Dipanjan; Lahkar, Vijay Kumar

2011-06-01

240

Recombinant production and structural studies of the Aplysia water-borne protein pheromone enticin indicates it has a novel disulfide stabilized fold.  

PubMed

Enticin is one of three Aplysia proteins released during egg laying that act in concert with the pheromone attractin to attract other Aplysia and stimulate mating behavior. Whereas the enticin cDNA predicts a 69-residue mature protein, enticin isolated from the albumen gland was found to be posttranslationally processed in vivo by cleavage at Arg(50) residue to generate a smaller 49-residue mature peptide. The Arg(50) cleavage site is conserved in enticin from both Aplysia californica and Aplysia brasiliana. In order to generate sufficient enticin for structural studies, recombinant full-length protein was produced in a soluble form in Escherichia coli using a cold shock promoter-based protein expression system. The enticin cDNA was cloned into the bacterial vector pCold III, and efficiently expressed, as determined by amino acid microsequence and immunoblot analyses. Recombinant enticin, which contained an additional N-terminal 13-residue translation-enhancing element, was purified by reversed-phase HPLC and compared to enticin isolated from the albumen gland. The three disulfide bonds in enticin were characterized by endoproteinase Glu-C proteolysis followed by mass spectrometric characterization of the fragments. The cysteine pairing, for both recombinant and native enticin, was I-II, III-IV, and V-VI, confirming that the protein produced in the bacterial system was correctly folded. The circular dichroism spectrum of the recombinant protein indicated it was predominantly alpha-helical. While this was consistent with fold recognition server results indicating a fold for enticin similar to that of attractin, the disulfide bonding pattern differs. A model for enticin was prepared based on its helical structure and these disulfide constraints. PMID:17141371

Cummins, Scott F; Xie, Fang; Misra, Milind; Amare, Andinet; Jakubowski, Jennifer A; de Vries, Melissa R; Sweedler, Jonathan V; Nagle, Gregg T; Schein, Catherine H

2007-01-01

241

Bioconversion of rice straw and certain agro-industrial wastes to amendments for organic farming systems: 1. Composting, quality, stability and maturity indices.  

PubMed

The microbiological and physicochemical parameters were monitored for 12 weeks during composting of five piles (1.5 x 1.0 x 0.80 m(3)) containing mainly rice straw, soybean residue and enriched with rock phosphate. Two treatments were inoculated with buffalo's manure or composite inoculum, two were supplemented with vinasse and inoculated with either the composite inoculum or with both, the last one was served as a control. Four typical phases of composting were observed during the bioprocess: short initial mesophilic phase followed by, thermophilic, cooling and maturation phases. Physicochemical changes confirmed the succession of microbial populations depending on the temperature of each phase in all treatments. Intense microbial activities led to organic matter mineralization and simultaneously narrow C/N ratios. Inoculation of composting mixtures enhanced the biodegradation of recalcitrant substances. The duration of exposure to a temperature above 55 degrees C for at least 16 consecutive days was quite enough to sanitize the produced composts. After 84 days, all composts reached maturity as indicated by various parameters. PMID:20335032

Rashad, Ferial M; Saleh, Walid D; Moselhy, Mohamed A

2010-08-01

242

Internet addiction: stability and change  

Microsoft Academic Search

This longitudinal study examined five indices of stability and change in Internet addiction: structural stability, mean-level\\u000a stability, differential stability, individual-level stability, and ipsative stability. The study sample was 351 undergraduate\\u000a students from end of freshman year to end of junior year. Convergent findings revealed stability rather than change in Internet\\u000a addiction. Prior academic self-concept was not associated with individual-level stability,

Chiungjung Huang

2010-01-01

243

Identification and Characterization of an Oxidative Degradation Product of Fexofenadine, Development and Validation of a Stability-Indicating RP-UPLC Method for the Estimation of Process Related Impurities and Degradation Products of Fexofenadine in Pharmaceutical Formulations.  

PubMed

A novel stability-indicating gradient RP-UPLC method was developed for the quantitative determination of process related impurities and forced degradation products of fexofenadine HCl in pharmaceutical formulations. The method was developed by using Waters Aquity BEH C18 (100 mm x 2.1 mm) 1.7 ?m column with mobile phase containing a gradient mixture of solvent A (0.05% triethyl amine, pH adjusted to 7.0 with ortho-phosphoric acid) and B (10:90 v/v mixture of water and acetonitrile). The flow rate of mobile phase was 0.4 mL/min with column temperature of 30°C and detection wavelength at 220nm. Fexofenadine HCl was subjected to the stress conditions including oxidative, acid, base, hydrolytic, thermal and photolytic degradation. Fexofenadine HCl was found to degrade significantly in oxidative stress conditions, and degradation product was identified and characterized by ESI-MS/MS, (1)H and (13)C NMR spectroscopic method as the N-oxide 2-[4-(1-hydroxy-4-{4-[hydroxy(diphenyl)methyl]-1-oxido-piperidin-1-yl}butyl)phenyl]-2-methylpropanoic acid. The degradation products were well resolved from fexofenadine and its impurities. The mass balance was found to be satisfactory in all the stress conditions, thus proving the stability-indicating capability of the method. The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of detection and quantification, accuracy, precision and robustness. PMID:22896817

Vaghela, Bhupendrasinh; Rao, Surendra Singh; Reddy, Annarapu Malleshwar; Venkatesh, Panuganti; Kumar, Navneet

2012-06-01

244

Complexity in estimation of esomeprazole and its related impurities' stability in various stress conditions in low-dose aspirin and esomeprazole magnesium capsules.  

PubMed

A complex, sensitive, and precise high-performance liquid chromatographic method for the profiling of impurities of esomeprazole in low-dose aspirin and esomeprazole capsules has been developed, validated, and used for the determination of impurities in pharmaceutical products. Esomeprazole and its related impurities' development in the presence of aspirin was traditionally difficult due to aspirin's sensitivity to basic conditions and esomeprazole's sensitivity to acidic conditions. When aspirin is under basic, humid, and extreme temperature conditions, it produces salicylic acid and acetic acid moieties. These two byproducts create an acidic environment for the esomeprazole. Due to the volatility and migration phenomenon of the produced acetic acid and salicylic acid from aspirin in the capsule dosage form, esomeprazole's purity, stability, and quantification are affected. The objective of the present research work was to develop a gradient reversed-phase liquid chromatographic method to separate all the degradation products and process-related impurities from the main peak. The impurities were well-separated on a RP8 column (150 mm × 4.6mm, X-terra, RP8, 3.5?m) by the gradient program using a glycine buffer (0.08 M, pH adjusted to 9.0 with 50% NaOH), acetonitrile, and methanol at a flow rate of 1.0 mL min(-1) with detection wavelength at 305 nm and column temperature at 30°C. The developed method was found to be specific, precise, linear, accurate, rugged, and robust. LOQ values for all of the known impurities were below reporting thresholds. The drug was subjected to stress conditions of hydrolysis, oxidation, photolysis, and thermal degradation in the presence of aspirin. The developed RP-HPLC method was validated according to the present ICH guidelines for specificity, linearity, accuracy, precision, limit of detection, limit of quantification, ruggedness, and robustness. PMID:23833714

Reddy, Palavai Sripal; Hotha, Kishore Kumar; Sait, Shakil

2013-06-01

245

Environmental Indicators  

NSDL National Science Digital Library

Environment Canada has developed a set of environmental indicators that are easily measurable and provide useful clues on the state of the environment. This Web site provides a listing of those indicators that Environment Canada monitors. For each indicator, there is a detailed description of the environmental indicator, how it relates to larger environmental problems, and what is being done to reduce the threat. A number of Web links are provided for further information on each indicator.

246

Development of a stability-indicating LC method for determination of a synthetic chalcone derivative in a nanoemulsion dosage form and identification of the main photodegradation product by LC-MS.  

PubMed

This study aimed to develop and validate a stability indicating LC for the determination of 5-(2-benzoylethenyl)-N-benzyl-2 methoxybenzenesulfonamide (SCD - a synthetic chalcone derivative), and evaluate the degradation profile of the compound under different stress conditions recommended by International Conference on Harmonization (ICH). Chromatographic separation was performed on a silica C18 column, methanol-water mobile phase 70:30 (v:v), pH 5.0 adjusted with the addition of trifluoroacetic acid (TFA) at a flow rate of 1.0 mL min(-1); detection by UV absorption at 330 nm. The method was validated for linearity, precision, accuracy, robustness and specificity. The SCD was subjected to forced degradation and peak photodegradation product was well separated from the pure substance, with retention times significantly different, indicating the specificity of the method. Second-order degradation kinetics of SCD was observed under photodegradation and base-induced degradation. In order to identify the product formed under photodegradation, liquid chromatography-tandem mass spectrometry (LC-MS/MS) was performed. These results indicate that the method can be successfully used in order to assay SCD in a nanoemulsion dosage form, and that this formulation has a protective effect over SCD degradation. PMID:22884784

Mattos, Cristiane B; Deponti, Vânia B; Barreto, Fabiano; Simões, Cláudia M O; Andrighetti-Frohner, Carla R; Nunes, Ricardo J; Steindel, Mário; Teixeira, Helder F; Koester, Letícia S

2012-11-01

247

UPLC and LC-MS studies on degradation behavior of irinotecan hydrochloride and development of a validated stability-indicating ultra-performance liquid chromatographic method for determination of irinotecan hydrochloride and its impurities in pharmaceutical dosage forms.  

PubMed

The objective of the current investigation was to study the degradation behavior of irinotecan hydrochloride under different International Conference on Harmonization (ICH) recommended stress conditions using ultra-performance liquid chromatography and liquid chromatography-mass spectrometry and to establish a validated stability-indicating reverse-phase ultra-performance liquid chromatographic method for the quantitative determination of irinotecan hydrochloride and its seven impurities and degradation products in pharmaceutical dosage forms. Irinotecan hydrochloride was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. Irinotecan hydrochloride was found to degrade significantly in oxidative and base hydrolysis and photolytic degradation conditions. The degradation products were well resolved from the main peak and its impurities, thus proving the stability-indicating power of the method. Chromatographic separation was achieved on a Waters Acquity BEH C8 (100 × 2.1 mm) 1.7-µm column with a mobile phase containing a gradient mixture of solvent A (0.02M KH(2)PO(4) buffer, pH 3.4) and solvent B (a mixture of acetonitrile and methanol in the ratio of 62:38 v/v). The mobile phase was delivered at a flow rate of 0.3 mL/min with ultraviolet detection at 220 nm. The run time was 8 min, within which irinotecan and its seven impurities and degradation products were satisfactorily separated. The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness. This method was also suitable for the assay determination of irinotecan hydrochloride in pharmaceutical dosage forms. PMID:22661461

Kumar, Navneet; Sangeetha, Dhanaraj; Reddy, Sunil P

2012-10-01

248

DETERMINATION OF A LINEAR ALKYLBENZENESULFONATE AND ITS BIODEGRADATION INTERMEDIATES IN SEA WATER USING SOLIDPHASE EXTRACTION AND RP-HPLC WITH UV DETECTION  

Microsoft Academic Search

A rapid and selective method for determining a linear alkylbenzenesulfonate (LAS) and its biodegradation metabolites in sea water samples using solid-phase extraction and reversed-phase high performance liquid chromatography with UV detection is proposed. A solid-phase extraction (SPE) procedure is described for concentrating the compounds of interest on Mega Bond Elut C18 mini-column cartridges (2 g of adsorbent). Factors affecting the

L. Sarrazin; W. Wafo; P. Rebouillon

1999-01-01

249

GRADIENT RP-HPLC DETERMINATION OF FREE PHENOLIC ACIDS IN WINES AND WINE VINEGAR SAMPLES AFTER SPE, WITH PHOTODIODE ARRAY IDENTIFICATION  

Microsoft Academic Search

The analysis of phenolic compounds in wines is of considerable commercial importance, since they are known to play the major role in defying the sensorial characteristics of wines, such as astringency, flavor, and color, as well as in the browning process, causing product deterioration. In this paper, an automated reversed phase high performance liquid chromatographic method, using a multistep binary

V. F. Samanidou; C. V. Antoniou; I. N. Papadoyannis

2001-01-01

250

Development and validation of a rapid RP-HPLC method for the determination of cetirizine or fexofenadine with pseudoephedrine in binary pharmaceutical dosage forms  

Microsoft Academic Search

The objective of the current study was to develop a simple, accurate, precise and rapid reversed-phase HPLC method and subsequent validation using ICH suggested approach for the determination of antihistaminic-decongestant pharmaceutical dosage forms containing binary mixtures of pseudoephedrine hydrochloride (PSE) with fexofenadine hydrochloride (FEX) or cetirizine dihydrochloride (CET). The chromatographic separation of PSE, FEX and CET was achieved on a

Sevgi Karaku?; ?lkay Küçükgüzel; ?. Güniz Küçükgüzel

2008-01-01

251

Application of Response Surface Methodology to Microwave-Assisted Extraction of Lysergol from Ipomoea Genus and Its Characterization by RP HPLC-UV  

Microsoft Academic Search

Objective  \\u000a Ipomoea genus is an excellent source of lysergol which is used as a hypotensive and psychrotopic analgesic. Microwave-assisted extraction\\u000a (MAE) was employed to extract lysergol from Ipomoea seeds, and response surface methodology (RSM) was applied to predict optimum conditions for extraction.\\u000a \\u000a \\u000a \\u000a \\u000a Methodology  Box–Behnken statistical design was used to monitor the effect of independent variables like temperature (A—50°C, 60°C, and\\u000a 70°C),

Shamama Javed; Kanchan Kohli; Mushir Ali

2011-01-01

252

Rapid determination of total solanesol in tobacco leaf by ultrasound-assisted extraction with RP-HPLC and ESI-TOF\\/MS  

Microsoft Academic Search

A reliable and rapid method based on high-performance liquid chromatography (HPLC-UV) and positive ion electrospray-time of flight mass spectrometry (ESI-TOF\\/MS) has been developed for the characterization and quantification of solanesol in extracts of tobacco leaves from different sources. The solanesol was extracted from tobacco leaf via saponification and ultrasonic-assist extraction, and the extraction conditions were optimized. The HPLC conditions are

Junhui Chen; Xianping Liu; Xiaoqin Xu; Frank Sen-Chun Lee; Xiaoru Wang

2007-01-01

253

Development and Validation of RP-HPLC Method for Simultaneous Estimation of Picroside I, Plumbagin, and Z-guggulsterone in Tablet Formulation.  

PubMed

The aim of the present work was to develop and validate a reversed-phase high-performance liquid chromatography method for the simultaneous estimation of picroside I, plumbagin, and Z-guggulsterone in a polyherbal formulation containing Picrorhiza kurroa, Plumbago zeylanica, and Commiphora wightii extracts. The analysis was performed on a C18 column using the mobile phase consisting of solvent A (acetonitrile) and solvent B (0.1% orthophosphoric acid in water) with the following gradient: 0-12 min, 25% A; 12-17 min, 25-80% A; 17-32 min, 80% A; and 32-37 min, 80-25% A at a flow rate of 1 ml/min. Ultraviolet detection was at 255 nm. The method was validated for accuracy, precision, linearity, specificity, and sensitivity as per the norms of the International Conference on Harmonization. From the validation study, it was found that the method is specific, accurate, precise, reliable, and reproducible. Good linear correlation coefficients (r(2)>0.900) were obtained for calibration plots in the ranges tested. Limits of detection were 2.700, 0.090 and 0.099 ?g/ml and limits of quantification were 9.003, 0.310, and 0.330 ?g/ml for picroside I, plumbagin, and Z-guggulsterone, respectively. Intra and interday relative standard deviation (RSD) of retention times and peak areas was less than 3.0%. Recovery was found to be 100.21% for picroside I, 102.5% for plumbagin, and 103.84% for Z-guggulsterone. The established method was appropriate and the three markers were well resolved, enabling efficient quantitative analysis of picroside I, plumbagin and Z-guggulsterone. The method is a rapid and cost-effective quality control tool for routine quantitative analysis of picroside I, plumbagin, and Z-guggulsterone in tablet dosage form. PMID:24302803

Akhade, Meenakshi S; Agrawal, Poonam A; Laddha, K S

2013-07-01

254

Simultaneous Estimation of Amlodipine Besylate and Indapamide in a Pharmaceutical Formulation by a High Performance Liquid Chromatographic (RP-HPLC) Method  

PubMed Central

An isocratic reversed-phase liquid chromatograpic assay method was developed for the quantitative determination of amlodipine besylate (AML) and indapamide (IND) in combined dosage form. A Brownlee C-18, 5 ?m column with a mobile phase containing 0.02 M potassium dihydrogen phosphate–methanol (30+70, v/v) total pH-adjusted to 3 using o-phosphoric acid was used. The flow rate was 1.0 mL min?1 and effluents were monitored at 242 nm. The retention times of amlodipine besylate and indapamide were 5.9 min and 3.6 min, respectively. The proposed method was validated with respect to linearity, accuracy, precision, and robustness. The method was successfully applied to the estimation of amlodipine besylate and indapamide in combined tablet dosage forms. PMID:23008807

Patel, Deval B.; Mehta, Falgun A.; Bhatt, Kashyap K.

2012-01-01

255

Development and validation of an RP-HPLC method to quantitate acyclovir in cross-linked chitosan microspheres produced by spray drying.  

PubMed

An accurate, simple, reproducible, and sensitive liquid chromatographic method is developed and validated to quantitate acyclovir (ACV) in cross-linked chitosan microspheres produced by spray drying. The analysis is carried out using a reversed-phase C18 column with UV-vis detection at 254 nm. The mobile phase is diluted with pure water and acetonitrile (95:5 v/v) at a flow-rate of 0.8 mL/min. The parameters used in the validation process are: linearity, range, quantitation limit, detection limit, accuracy, specificity precision, and ruggedness. The retention time of acyclovir is approximately 3.5 min with symmetrical peaks. The linearity in the range of 1-10 microg/mL presents a correlation coefficient of 0.9999. The chitosan and the tripolyphosphate in the formulation do not interfere with the analysis, and the recovery is quantitative. Results are satisfactory, and the method proves to be suitable to quantitate ACV in cross-linked chitosan microspheres. PMID:18647469

Stulzer, Hellen K; Tagliari, Monika Piazzon; Murakami, Fábio S; Silva, Marcos A S; Laranjeira, Mauro C M

2008-07-01

256

Determination of biogenic amines in traditional Chinese fermented foods by reversed-phase high-performance liquid chromatography (RP-HPLC).  

PubMed

A survey of biogenic amine content of traditional Chinese fermented foods (douchi, sufu, fermented sausage, yulu, and shrimp paste) was carried out. Eight major biogenic amines including putrescine, cadaverine, histamine, phenylethylamine, tyramine, spermine, spermidine and tryptamine were separated by reversed-phase HPLC-DAD on Inertsil ODS-SP column after pre-column derivatisation with dansyl chloride. The results showed that spermine (1.65-3.96 mg 100 g(-1)), putrescine (0.20-10.89 mg 100 g(-1)), cadaverine (3.60-12.14 mg 100 g(-1)), and histamine (0.57-20.24 mg 100 g(-1)) were the most represented amines. All amines were detected in yulu, while sufu showed a much higher content of most amines. Shrimp paste showed the lowest level of total biogenic amines. Moreover, the composition and content of eight biogenic amines in the selected samples varied among different food types, origins and batches. Although the average content for each amine is within the range that may elicit direct adverse reactions, consumers should be aware of the potential synergistic effect among different amines and limit their consumption at each meal. PMID:24844287

Gong, Xiao; Wang, Xiaoxi; Qi, Ningli; Li, Jihua; Lin, Lijing; Han, Zhiping

2014-08-01

257

Development and validation of an ion-pairing RP-HPLC method for the estimation of gatifloxacin in bulk and formulations.  

PubMed

A new, simple, and sensitive ion-pair reverse-phase liquid chromatographic method is developed and validated for the estimation of 1-cyclopropyl-6-fluoro-8-methoxy-7-(3-methylpiperazin-1-yl)-4-oxo-1,4-dihydro-quinoline-3-carboxylic acid (gatifloxacin) in bulk and formulations using a UV detector under isocratic conditions. The selected mobile phase consists of the aqueous phase (a 25 mM citrate buffer comprising of 10mM cationic and anionic pairing agents, pH adjusted to 3.5) and acetonitrile (52:48%, v/v). The selected wavelength is 292 nm. Retention time of gatifloxacin is 5.2 min. The linearity range is found to be 50 to 1000 ng/mL (the regression equation is area = 105.5 x concentration in ng/mL--695.8), and the regression coefficient is 0.9996. Validation results demonstrate accuracy, precision, and reproducibility (relative standard deviation < 3%) of the method. The detection and quantitation limits are found to be 6.50 and 17.38 ng/mL, respectively. The method is successfully used for the estimation of gatifloxacin in a variety of dosage forms, and the results are in good agreement with the label claims. PMID:17504572

Venugopal, Kolachina; Snehalatha, Movva; Bende, Girish; Saha, Ranendra

2007-04-01

258

Migration study of optical brighteners from polymer packing materials to jam squeeze and fruit drink by spectrofluorimetry and RP-HPLC methods.  

PubMed

Optical brighteners are commonly used to modify the appearance and to improve polymer properties of packaging. They are not chemically bound to polymers and able to migrate from packaging into the foods. These migrants are potentially harmful to human health. In concern with human safety an approach was made to analyze three optical brighteners such as diphenylbutadiene, Uvitex-OB, benzophenone in commercial fruit juice and jam. The migration level of these optical brighteners from low density poly ethylene packaging into fruit juice and jam was studied. Two optimized and validated analytical techniques such as spectrofluorimetry and high performance liquid chromatography with photo diode array detector used for migration study. Both methods have shown high correlation coefficients (>0.999), over a concentration range of 0.1-3.2 ?g/mL, 0.1-1 ?g/mL, 0.05-3.2 ?g/mL for diphenylbutadiene, Uvitex-OB and benzophenone respectively. The preliminary studies confirm that the low density poly ethylene layer taken for study contained of diphenylbutadiene and the other two were absent. The migration level of diphenylbutadiene was studied at room temperature and different elevated temperature from 30 °C to 60 °C for up to 3 weeks. At room temperature no migration of diphenylbutadiene was observed where as at higher temperature migration could be observed. The maximum quantity of diphenylbutadiene migrated was found to be 0.0462 mg/kg from tetrapak, and 0.0382 mg/kg from jam squeeze after 3 weeks treatment at 60 °C. The migration of diphenylbutadiene was found to be less than allowable concentration during the study period. PMID:24876646

Gandhimathi, M; Murugavel, K; Ravi, T K

2014-06-01

259

Characterisation of soft cheese proteolysis by RP-HPLC analysis of its nitrogenous fractions. Effect of ripening time and sampling zone  

Microsoft Academic Search

Port Salut Argentino cheeses were studied at different ripening times (1, 6, 13, 27 and 56 days) and two sampling zones (central and external). Moisture content, salt concentration, water-insoluble fraction, water-soluble fraction, and free amino acids in the sulphosalicylic acid-soluble fraction were analysed. Moisture and salt contents at the beginning of ripening were higher in the external zone than in

R. A. Verdini; S. E. Zorrilla; A. C. Rubiolo

2004-01-01

260

Isotherm models for localized monolayers with lateral interactions. Application to single-component and competitive adsorption data obtained in RP-HPLC  

SciTech Connect

Single-component and competitive adsorption data of 2-phenylethanol and 3-phenylpropanol on ODS-silica with methanol-water as the mobile phase, which had been previously reported, were reinterpreted. These data were fitted to several isotherm models derived from statistical thermodynamics which considered lateral adsorbate-adsorbate interactions on homogeneous surfaces: the Fowler, Ruthven, and Moreau et al. models. The single-component Kiseleve model for specific lateral interactions was extended to account for the competitive adsorption of binary mixtures and for the finite or infinite dimension of the adsorbed associates. These last models were tested using the same set of experimental data. A comparison was made regarding the ability of these models to predict mixed equilibria using only the identified parameters of the single-component isotherms. In this regard, the best result were obtained with the Kiselev model, which considers the formation of both binary and ternary associates on the surface. 41 refs., 2 figs., 2 tabs.

Quinones, I. [Centro de Quimica Farmaceutica, Habana (Cuba); Guiochon, G. [Univ., of Tennessee, Knoxville, TN (United States)] [Univ., of Tennessee, Knoxville, TN (United States); [Oak Ridge National Lab., TN (United States)

1996-10-30

261

Turn indicator  

NASA Technical Reports Server (NTRS)

This report presents a study of an instrument that can warn the pilot of the turning of his airplane. This instrument must satisfy three conditions: 1) It must give useful indication immediately from take-off; 2) The indications must be instantaneous and require no exertion by the pilot; 3) The indicator must be sensitive only to changes of orientation in the horizontal plane. Different solutions are presented such as a gyroscope driven by the suction of a Venturi tube.

De Guiche, A De Gramont

1922-01-01

262

Community indicators  

PubMed Central

Community indicators are used to assess the impact of alcohol on communities. This article reviews the main data sources for community indicators, discusses their strengths and limitations, and discusses indicators used in reference to four main topics relating to alcohol use and problems at the community level: alcohol use, patterns, and problems; alcohol availability; alcohol-related health outcomes/trauma; and alcohol-related crime and enforcement. It also reviews the challenges associated with collecting community indicator data, along with important innovations in the field that have contributed to better knowledge of how to collect and analyze community-level data on the impact of alcohol. PMID:24881322

Flynn, Andrea; Wells, Samantha

2014-01-01

263

Engagement Indicators Theme Engagement Indicator  

E-print Network

in magnitude. Due to their positive associations with student learning and retention, special undergraduateSnapshot Engagement Indicators Theme Engagement Indicator Higher-Order Learning (HO) Reflective) Discussions with Diverse Others (DD) -- Student-Faculty Interaction (SF) Effective Teaching Practices (ET

Bogaerts, Steven

264

Development and Validation of a Stability-Indicating Capillary Electrophoresis Method for the Determination of Zolpidem Tartrate in Tablet Dosage Form with Positive Confirmation using 2D- and 3D-DAD Fingerprints  

PubMed Central

The aim of the current study was to develop a simple, precise, and accurate capillary zone electrophoresis method for the determination of zolpidem tartrate in tablet dosage form. Separation was conducted in normal polarity mode at 25°C, 22 kV, using hydrodynamic injection for 10 s. Separation was achieved using a background electrolyte of 20 mM disodium hydrogen phosphate adjusted with phosphoric acid (85%), pH at 5.50, and detection at 254 nm. Using the above optimized conditions, complete determination took place in less than 3 min using amiloride HCl as the internal standard. The method was linear over the range of 3–1000 ?g mL?1 with a correlation coefficient of 0.9999. Forced degradation studies were conducted by introducing a sample of zolpidem tartrate standard and pharmaceutical sample solutions to different forced degradation conditions, being neutral (water), basic (0.1 M NaOH), acidic (0.1 M HCl), oxidative (10% H2O2), temperature (60°C in oven for 3 days), and photolytic (exposure to UV light at 254 nm for 2 h). Degradation products resulting from the stress studies did not interfere with the detection of zolpidem tartrate and the assay can be considered stability-indicating. PMID:24959406

Al Azzam, Khaldun M.; Yit, Lee Kam; Saad, Bahruddin; Shaibah, Hassan

2014-01-01

265

Development and Validation of a Stability-Indicating Capillary Electrophoresis Method for the Determination of Zolpidem Tartrate in Tablet Dosage Form with Positive Confirmation using 2D- and 3D-DAD Fingerprints.  

PubMed

The aim of the current study was to develop a simple, precise, and accurate capillary zone electrophoresis method for the determination of zolpidem tartrate in tablet dosage form. Separation was conducted in normal polarity mode at 25°C, 22 kV, using hydrodynamic injection for 10 s. Separation was achieved using a background electrolyte of 20 mM disodium hydrogen phosphate adjusted with phosphoric acid (85%), pH at 5.50, and detection at 254 nm. Using the above optimized conditions, complete determination took place in less than 3 min using amiloride HCl as the internal standard. The method was linear over the range of 3-1000 ?g mL(-1) with a correlation coefficient of 0.9999. Forced degradation studies were conducted by introducing a sample of zolpidem tartrate standard and pharmaceutical sample solutions to different forced degradation conditions, being neutral (water), basic (0.1 M NaOH), acidic (0.1 M HCl), oxidative (10% H2O2), temperature (60°C in oven for 3 days), and photolytic (exposure to UV light at 254 nm for 2 h). Degradation products resulting from the stress studies did not interfere with the detection of zolpidem tartrate and the assay can be considered stability-indicating. PMID:24959406

Al Azzam, Khaldun M; Yit, Lee Kam; Saad, Bahruddin; Shaibah, Hassan

2014-06-01

266

Metallic alloy stability studies  

NASA Technical Reports Server (NTRS)

The dimensional stability of candidate cryogenic wind tunnel model materials was investigated. Flat specimens of candidate materials were fabricated and cryo-cycled to assess relative dimensional stability. Existing 2-dimensional airfoil models as well as models in various stages of manufacture were also cryo-cycled. The tests indicate that 18 Ni maraging steel offers the greatest dimensional stability and that PH 13-8 Mo stainless steel is the most stable of the stainless steels. Dimensional stability is influenced primarily by metallurgical transformations (austenitic to martensitic) and manufacturing-induced stresses. These factors can be minimized by utilization of stable alloys, refinement of existing manufacturing techniques, and incorporation of new manufacturing technologies.

Firth, G. C.

1983-01-01

267

Development and Validation of a Simultaneous HPLC Method for Estimation of Bisoprolol Fumarate and Amlodipine Besylate from Tablets  

PubMed Central

A fast, robust and stability indicating RP-HPLC method was developed for simultaneous determination of bisoprolol fumarate and amlodipine besylate in tablets. The mobile phase was mixture of 25 mM ammonium acetate adjusted to pH 5.0 and methanol (65: 35) at 0.8 ml/min. The stationary phase was Luna C18-2 column (3 ?, 50×4.6 mm ID). UV detection was performed at 230 nm. Retention time was 1.45 min and 3.91 min for bisoprolol and amlodipine, respectively. Linearity was established in the range of 8–33 ?g/ml. Mean recovery was 99.1% and 98.6% for bisoprolol fumarate and amlodipine besylate, respectively. PMID:20046793

Vora, D. N.; Kadav, A. A.

2008-01-01

268

Analysis of cephalosporins by hydrophilic interaction chromatography.  

PubMed

A simple hydrophilic interaction chromatography (HILIC) method was developed to analyze seven cephalosporins. These seven cephalosporins could be separated well on the Click ?-CD column and Atlantis HILIC Silica column. The effects of buffer concentration and pH on the retention under HILIC mode were studied. Except cefepime hydrochloride (4), the retention of other six cephalosporins increased with increasing buffer concentration, while decreased with increasing pH. Different separation selectivities could be observed on the Click ?-CD column and Atlantis HILIC Silica column, and changing pH also resulted in the changing of separation selectivity. The separations of cephalosporins by HILIC and reversed-phase high performance liquid chromatography (RP-HPLC) were compared, and the two separation modes had good orthogonality. In addition, cefotaxime sodium (1) and its degradation were separated well on the Click ?-CD column, which indicated that the Click ?-CD column by HILIC can be used for studying the stability of cephalosporins. PMID:21035295

Liu, Qiaoxia; Xu, Lingyan; Ke, Yanxiong; Jin, Yu; Zhang, Feifang; Liang, Xinmiao

2011-02-20

269

Indices to detect Hopf bifurcation in Induction motor drives  

E-print Network

The loss of stability of induction motor controlled by Indirect Field Oriented Control (IFOC) is a matter of great concern of operators and design engineers. This paper reports indices to detect and predict stability problem such as system oscillations. Oscillations as a result of loss of stability, due to Hopf bifurcation, for different parameter values of IFOC motor are studied using the proposed indices.

Krishnendu Chakrabarty; Urmila Kar

2014-10-24

270

Automatic stabilization  

NASA Technical Reports Server (NTRS)

This report concerns the study of automatic stabilizers and extends it to include the control of the three-control system of the airplane instead of just altitude control. Some of the topics discussed include lateral disturbed motion, static stability, the mathematical theory of lateral motion, and large angles of incidence. Various mechanisms and stabilizers are also discussed. The feeding of Diesel engines by injection pumps actuated by engine compression, achieves the required high speeds of injection readily and permits rigorous control of the combustible charge introduced into each cylinder and of the peak pressure in the resultant cycle.

Haus, FR

1936-01-01

271

Membrane stabilizer  

DOEpatents

A device is provided for stabilizing a flexible membrane secured within a frame, wherein a plurality of elongated arms are disposed radially from a central hub which penetrates the membrane, said arms imposing alternately against opposite sides of the membrane, thus warping and tensioning the membrane into a condition of improved stability. The membrane may be an opaque or translucent sheet or other material. 10 figs.

Mingenbach, W.A.

1988-02-09

272

Stabilization of supersaturated zincate solutions  

SciTech Connect

This paper investigates the stabilization of supersaturated zincate electrolytes in a silver-zinc battery by the addition of potassium hydroxide, lithium hydroxide, and molasses. Molasses, in combination with the hydroxide additives, was found to demonstrate a profound stabilizing influence on the zincate supersaturation and the electrolyte. Preliminary data on discharge of a battery using the combined additive indicates that it has higher discharge capacity than do batteries which contain the individual additives. The chemistry of this stabilizing influence is discussed.

Dmitrenko, V.E.; Zubov, M.S.; Baulov, V.I.; Balyakina, N.N.; Kotov, A.V.

1986-09-10

273

Slope Stability  

NSDL National Science Digital Library

This activity introduces students to the concept of slope stability (or angle of repose). Using an apparatus they have constructed, the students will work in small groups to test the stability angle of fine gravel, sand, and topsoil, gradually increasing the angle of the apparatus until the test material begins to slide off (angle of first fall) and until all the material slides away (angle of total fall). They will record these values and note which materials held the steepest slopes. As an extension, they can mix the test materials and observe the effects of mixing grain sizes. A student worksheet and discussion questions are provided.

274

Laser Stabilization  

SciTech Connect

This book chapter covers the basics of the field of stabilizing lasers to optical frequency references such as optical cavities and molecular transitions via the application of servo control systems. These discussions are given with reference to the real-life frequency metrology experienced in Hall-Labs (now Ye-Labs), JILA, University of Colorado. The subjects covered include: the basics of control system stability, a discussion of both the theoretical and experimental limitations, an outline of optical cavity susceptibility to environmental noise, and a brief introduction to the use and limitations of molecular transitions as frequency references.

Hall, John L.; Taubman, Matthew S.; Ye, Jun

2010-01-01

275

Stability-indicating methods for the spectrophotometric determination of norfloxacin  

Microsoft Academic Search

Two spectrophotometric procedures for the selective determination of norfloxacin (NF) in the presence of its decarboxylated degradant are described. The first depends upon measurement of the pH-induced absorbance difference (?A) of the drug solution between 0.1 N HCl and 0.1 N NaOH at 280 nm. The second involves chelation of the intact drug with iron(II) in acetate buffer solution (pH

Sonia Z. El Khateeb; Sawsan A. Abdel Razek; M. M. Amer

1998-01-01

276

A Stability Indicating LC Method for Vardenafil HCl  

Microsoft Academic Search

A simple, sensitive gradient RP-LC assay method has been developed for the quantitative determination of vardenafil HCl in\\u000a bulk drug and in pharmaceutical dosage forms, used to treat erectile dysfunction. The developed method is also applicable\\u000a for the related substances determination. Efficient chromatographic separation was achieved on a C18 stationary phase with\\u000a simple mobile phase combination delivered in a gradient

D. V. Subba Rao; K. V. Surendranath; P. Radhakrishnanand; M. V. Suryanarayana; P. Raghuram

2008-01-01

277

Stability-indicating methods for the determination of disopyramide phosphate.  

PubMed

Four methods were developed for the determination of intact disopyramide phosphate in the presence of its degradation product. In the first and second methods, third-derivative spectrophotometry and first derivative of the ratio spectra were used. For the third-derivative spectrophotometric method, the peak amplitude was measured at 272 nm, while for the derivative ratio spectrophotometric method, disopyramide phosphate was determined by measuring the peak amplitude at 248 and 273 nm. Both methods were used for the determination of disopyramide phosphate in the concentration range 12.5-87.5 microg/mL, with corresponding mean recovery 100.8 +/- 0.7% for the first method and 99.9 +/- 0.7% and 99.6 +/- 0.7% for the second method at 248 and 273 nm, respectively. In the third method, an ion selective electrode (ISE) was fabricated using phosphotungstic acid as an anionic exchanger, PVC as the polymer matrix, and dibutylsebacate as a plasticizer. The ISE was used for the determination of disopyramide phosphate in pure powder form in the concentration range 10(-2)-10(-5) M. The slope was found to be 58.5 (mV/decade), and the average recovery was 99.9 +/- 1.6%. The fourth method depended on the quantitative densitometric determination of the drug in concentration range of 0.25-2.5 microg/spot using silica gel 60 F245 plates and ethyl acetate-chloroform-ammonium hydroxide (85 + 10 + 5, v/v/v) as the mobile phase, with corresponding mean accuracy of 100.3 +/- 1.1%. The 4 proposed methods were found to be specific for disopyramide phosphate in presence of up to 80% of its degradation product for the spectrophotometric methods, 90% of its degradation for the densitometric method, and 40% for the ISE method. The 4 proposed procedures were successfully applied for the determination of disopyramide phosphate in Norpace capsules. Statistical comparison between the results obtained by these methods and the official method of the drug was done, and no significant differences were found. PMID:16915833

Salem, Maissa Y; Ramadan, Nesrin K; Moustafa, Azza A; El-Bardicy, Mohamed G

2006-01-01

278

Aggregate-Size Stability Distribution and Soil Stability  

Microsoft Academic Search

These indices account for the total weighted average of stable aggre- gates and the total weighted average of stable macroaggregates, re- release of this large buildup of internal air pressure spectively. Both the SAI and the SMaI indices were shown to be (Cambardella and Elliott, 1993a; Gale et al., 2000). sensitive to the effects of vegetation on soil stability under

C. O. Márquez; V. J. Garcia; C. A. Cambardella; R. C. Schultz; T. M. Isenhart

2004-01-01

279

An optimized and validated RP-HPLC\\/UV detection method for simultaneous determination of all-trans-Retinol (Vitamin A) and ?-Tocopherol (Vitamin E) in human serum: Comparison of different particulate reversed-phase HPLC columns  

Microsoft Academic Search

A novel, simple and fast reversed-phase HPLC\\/UV method was developed, optimized for various chromatographic conditions, and validated according to international guidelines for simultaneous determination of all-trans-retinol and ?-tocopherol in human serum using retinyl acetate as internal standard in the concentration of 0.5?g\\/ml. A liquid-phase extraction was applied to the 250?l of serum with n-hexane–dichloromethane mixture (70:30, v\\/v), in two steps,

Abad Khan; Muhammad I. Khan; Zafar Iqbal; Yasar Shah; Lateef Ahmad; David G. Watson

2010-01-01

280

Indices of landscape pattern  

Microsoft Academic Search

Landscape ecology deals with the patterning of ecosystems in space. Methods are needed to quantify aspects of spatial pattern that can be correlated with ecological processes. The present paper develops three indices of pattern derived from information theory and fractal geometry. Using digitized maps, the indices are calculated for 94 quadrangles covering most of the eastern United States. The indices

R. V. O'Neillr; J. R. Krummel; R. H. Gardner; G. Sugihara; B. Jackson; D. L. DeAngelist; B. T. Milne; M. G. Turner; B. Zygmunt; S. W. Christensen; V. H. Dale; R. L. Graham

1988-01-01

281

Stability of climate reconstructions  

NASA Astrophysics Data System (ADS)

Reconstruction of climate mode indices using proxy data as predictors is limited due to non-stationarity in atmospheric teleconnections. In this paper a method is presented to identify stable predictors for the reconstruction of the Arctic Oscillation (AO) index. Using the 20th Century reanalysis data, the AO index is calculated for the last 140 years and correlated with global two meter temperature, precipitation, and sea surface temperature anomalies in various moving windows. The stability of the correlation was checked in every point of the global grids. Anomalies from the regions where the correlation of the AO index is stable are used as stable predictors for the AO index. It is shown that the predictors identified through our analysis lead to proper AO reconstructions. Statistical analysis of a global climate simulation covering the last millennium reveals that the stability correlation map of model AO and temperature are very similar to the corresponding observed correlation stability map. It is shown that the stability correlation maps of the AO, as derived from the model, are insensitive to different climate forcing and can be used to systematically select stable predictors for the AO reconstruction during the last millennium and most likely for the late Holocene. Finally, several high resolution proxy data from the stable regions are selected and used for a reconstruction of the AO index during the last three centuries. We argue that selection of proxy data from the stable regions of AO teleconnections leads to a suitable AO reconstruction. Furthermore, the hypothesis of stable teleconnections is tested using atmospheric circulation model experiments. For climate conditions with other ice sheet distributions on the Northern Hemisphere, such as the last glacial maximum climate, considerable changes are detected in the atmospheric variability pattern compared to the present day. Correlation maps of pseudo proxy records over Europe, the Red Sea area, and Greenland indicate that the associated wind pattern can change drastically. During glacial times, Greenland ice cores indicate cold and warm phases in the northern North Atlantic. When looking in detail for the interannual variability for these phases, model simulations indicate that Greenland temperature variations are linked to distinct large-scale Northern Hemisphere circulation patterns and associated local wind directions. It is argued that such analysis provides a dynamical interpretation of past climate variability. With the combined use of models and data, one can examine the representativeness of sites where the reconstructions are available.

Lohmann, Gerrit; Rimbu, Norel; Wagner, Axel; Dima, Mihai

2014-05-01

282

Welding-Current Indicator  

NASA Technical Reports Server (NTRS)

Light flashes on to indicate high current. Simple, inexpensive display circuit indicates when 3,000-A welding current flows in welding gun. Onset of welding current induces voltage and current in 1,000-turn, 28-gauge copper-wire coil. Single-transistor amplifier amplifies induced current, energizing light-emitting diode (LED) connected to collector of transistor. Light from LED gives simple, direct indication of welding current.

Hensley, Milton C.; Huston, Steven W.; Kroy, Ralph E.

1990-01-01

283

Development and application of a novel, dual-mode gradient, stability-indicating HPLC-DAD method for the simultaneous determination and purity assessment of mebeverine hydrochloride, diloxanide furoate and their corresponding major degradation products in combination with some gastrointestinal drugs in the form of oral doses.  

PubMed

A simple, precise, rapid, stability-indicating reversed phase high performance liquid chromatographic method with photodiode array detection was developed and validated for the determination of mebeverine hydrochloride in combination with sulpiride or with diloxanide furoate and metronidazole in the presence of their corresponding degradation products. Optimum separation was achieved in less than 10 min using an X-Bridge C18 column (150 mm × 4.6 mm i.d., 3.5 ?m particle size); elution was accomplished via the application of a dual-mode solvent and flow rate gradient system. This elution system enables the separation of nine components within a cycle time of 15 min and with a resolution greater than 2.5. Detection was conducted at 230 nm, and purity assessment was performed using a photodiode array detector. The method has been validated with respect to specificity, linearity, accuracy, precision, limit of quantitation, limit of detection, robustness and ruggedness. The validation criteria were met in all cases. The developed HPLC method was successfully applied to commercial tablets. It was shown that this method is very sensitive to the determination of the degradation products, downward to 0.1 w/w% levels, which is far below the limits for testing these degradation products within their corresponding intact drugs. PMID:23770637

Mabrouk, Mokhtar; El-Fatatry, Hamed; Hewala, Ismail; Emam, Ehab

2013-09-01

284

Marine Organisms as Indicators  

NASA Astrophysics Data System (ADS)

The term “indicator organism” can have a variety of meanings. In its narrowest and perhaps most often used sense, an indicator organism is a single species whose abundance, physiological state, or reproductive success gives the investigator information about the environmental conditions to which it has been exposed. The indicator concept has been employed traditionally by regulatory agencies to assess the consequence of anthropogenic activity, using the indicator species as a surrogate for the ecosystem as a whole. The concept of a single-indicator species useful for such purposes is, however, as one of the editors points out, “illusory as the search for alchemist's gold,” and if the reader expects that this volume contains only a review of the use of indicator organisms in pollution monitoring, he or she will be greatly surprised. The editors have instead chosen a broad definition of indicator organisms and applications. The result is that the “indicator organism” may not be an organism at all (e.g., the paper by G. S. Kleppel on pigments as trophodynamic indicators), and the environmental information conveyed, such as climatic changes or the presence of mesoscale oceanic features, is most often unrelated to man's activities.

Weston, Donald P.

285

Heat stability of milk emulsions: phospholipid–protein interactions  

Microsoft Academic Search

Certain types of lecithin increase the heat stability of recombined and conventional full-cream evaporated milk but the mechanism is unknown. Previous studies have indicated the importance of fat in the system. New studies have indicated the nature of protein–lecithin interactions involved in improving heat stability. Two likely mechanisms were considered: (a) that lecithin increases heat stability by displacement of or

Catharina H McCrae

1999-01-01

286

Composite stabilizer unit  

DOEpatents

An improved fin stabilized projectile including multiple stabilizer fins upon a stabilizer unit situated at the aft end of the projectile is provided, the improvement wherein the stabilizer fins are joined into the stabillizer unit by an injection molded engineering grade polymer.

Ebaugh, Larry R. (Los Alamos, NM); Sadler, Collin P. (Los Alamos, NM); Carter, Gary D. (Espanola, NM)

1992-01-01

287

Quality Indicator System Report.  

ERIC Educational Resources Information Center

This report is a product of the implementation of a quality indicator system for Colorado's public higher education system. In 1999, the Colorado Commission on Higher Education established a core set of nine indicators, for which data were gathered and benchmarks were identified for measuring performance in terms of these benchmarks. The first…

Colorado Commission on Higher Education, Denver.

288

Performance Indicators Revisited.  

ERIC Educational Resources Information Center

Information was gathered about how Technical and Further Education (TAFE) agencies throughout Australia were implementing and using performance indicators. The context of TAFE's perceived mission and corporate goals were considered. A history of the development of national performance indicators in TAFE was compiled. The project drew heavily on…

Guthrie, Hugh

289

Terrestrial Indicators and Measurements  

E-print Network

THE CRITERIA. 5 STEP 4. RATE THE INDICATORS AGAINST THE CRITERIA. 5 STEP 5. DEVELOP AND APPLY SYSTEM. TESTS FOR POTENTIAL INDICATOR SELECTION BIAS ASSOCIATED WITH EXPERTISE AND LEVEL OF KNOWLEDGE 27 standardized measurements allows data to be integrated across field office, district and state boundaries

290

Indicators for energy security  

Microsoft Academic Search

The concept of energy security is widely used, yet there is no consensus on its precise interpretation. In this research, we have provided an overview of available indicators for long-term security of supply (SOS). We distinguished four dimensions of energy security that relate to the availability, accessibility, affordability and acceptability of energy and classified indicators for energy security according to

Bert Kruyt; D. P. van Vuuren; H. J. M. de Vries; H. Groenenberg

2009-01-01

291

The Stability of Leisure Preferences.  

ERIC Educational Resources Information Center

This study investigated the stability of leisure preferences across a two-year time span. Data collected from 126 married couples indicated that preferences for specific leisure activities were significantly and positively correlated across the time period and that reported preferences for specific leisure activities declined over time. (Author/CB)

Crawford, Duane W.; And Others

1986-01-01

292

Cabbage Juice Indicator  

NSDL National Science Digital Library

In this chemistry activity, learners make indicator solution from red cabbage. Then, learners test everyday foods and household substances using the cabbage juice indicator. Learners will record the color change, approximate pH (using the pH scale), and identify if it is an acid or base. As an extension, learners can make pH paper strips to conduct an "at home" pH test of other household items. The indicator solution can be frozen in ice trays and when mixed with alcohol, can last for months. For safety reasons, adult supervision is recommended.

House, The S.

2014-01-28

293

Stability analysis and stabilization strategies for linear supply chains  

NASA Astrophysics Data System (ADS)

Due to delays in the adaptation of production or delivery rates, supply chains can be dynamically unstable with respect to perturbations in the consumption rate, which is known as “bull-whip effect”. Here, we study several conceivable production strategies to stabilize supply chains, which is expressed by different specifications of the management function controlling the production speed in dependence of the stock levels. In particular, we will investigate, whether the reaction to stock levels of other producers or suppliers has a stabilizing effect. We will also demonstrate that the anticipation of future stock levels can stabilize the supply system, given the forecast horizon ? is long enough. To show this, we derive linear stability conditions and carry out simulations for different control strategies. The results indicate that the linear stability analysis is a helpful tool for the judgement of the stabilization effect, although unexpected deviations can occur in the non-linear regime. There are also signs of phase transitions and chaotic behavior, but this remains to be investigated more thoroughly in the future.

Nagatani, Takashi; Helbing, Dirk

2004-04-01

294

World Development Indicators, 2011.  

National Technical Information Service (NTIS)

World Development Indicators 2011, the 15th edition in its current format, aims to provide relevant, high-quality, internationally comparable statistics about development and the quality of peoples lives around the globe. This edition of World Development...

2011-01-01

295

World Development Indicators, 2012.  

National Technical Information Service (NTIS)

World Development Indicators 2012 is a compilation of relevant, high-quality, and internationally comparable statistics about development and the quality of peoples lives. Organized around six themesworld view, people, the environment, the economy, states...

2012-01-01

296

New England Economic Indicators  

NSDL National Science Digital Library

New England Economic Indicators, a monthly publication from the Federal Reserve Bank of Boston, contains articles on subjects including labor market conditions, consumer prices, consumer confidence, and electricity sales.

297

Indicators: Change from  

E-print Network

St. Paul North- West Health Science East Bank Central Svcs. U&E Admin Preventative Maintenance: Fire of performance measures and specific color code target values. Trend status color indicators ­ identifies changes

Webb, Peter

298

Indicators: Performance Statistics  

E-print Network

1 2 3 4 5 Central Svcs. U&E Admin Preventative Maintenance: Fire/Life/Safety (FLS) 88% -1% 100% 100 and specific color code target values. Trend status color indicators ­ identifies changes from the prior month

Webb, Peter

299

Indicators: Change from  

E-print Network

St. Paul North- West Health Science East Bank Central Svcs. U&E Admin Preventative Maintenance: Fire for descriptions of performance measures and specific color code target values. Trend status color indicators

Webb, Peter

300

General Indicators: Change from  

E-print Network

Central Svcs. U&E Admin Preventative Maintenance: Fire/Life/Safety (FLS) 96% -3% 100% 100% 100% 82% 98 measures and specific color code target values. Trend status color indicators ­ identifies changes from

Webb, Peter

301

Indicators: Performance Statistics  

E-print Network

4 5 Central Svcs. U&E Admin Preventative Maintenance: Fire/Life/Safety (FLS) 89% -4% 100% 100% 100 of performance measures and specific color code target values. Trend status color indicators ­ identifies changes

Webb, Peter

302

General Indicators: Change from  

E-print Network

&E Admin Preventative Maintenance: Fire/Life/Safety (FLS) 99% +8% 100% 100% 100% 98% 94% 100% Non-FLS 92 measures and specific color code target values. Trend status color indicators ­ identifies changes from

Webb, Peter

303

Indicators: Change from  

E-print Network

Initial Target 1 2 3 4 5 Central Svcs. U&E Admin Preventative Maintenance: Fire/Life/Safety (FLS) 85% -9 for descriptions of performance measures and specific color code target values. Trend status color indicators

Webb, Peter

304

Indicators: Performance Statistics  

E-print Network

1 2 3 4 5 Central Svcs. U&E Admin Preventative Maintenance: Fire/Life/Safety (FLS) 93% +5% 100% 100 measures and specific color code target values. Trend status color indicators ­ identifies changes from

Webb, Peter

305

General Indicators: Change from  

E-print Network

Maintenance: Fire/Life/Safety (FLS) 99% No Change 100% 100% 100% 99% 100% 100% Non-FLS 88% -2% 85% 99% 96 and specific color code target values. Trend status color indicators ­ identifies changes from the prior month

Webb, Peter

306

Indicators: Performance Statistics  

E-print Network

Previous Month Initial Target 1 2 3 4 5 Central Svcs. U&E Admin Preventative Maintenance: Fire for descriptions of performance measures and specific color code target values. Trend status color indicators

Webb, Peter

307

Indicators: Change from  

E-print Network

Target 1 2 3 4 5 Central Svcs. U&E Admin Preventative Maintenance: Fire/Life/Safety (FLS) 90% +11% 100 and specific color code target values. Trend status color indicators ­ identifies changes from the prior month

Webb, Peter

308

Indicators: Change from  

E-print Network

Target 1 2 3 4 5 Central Svcs. U&E Admin Preventative Maintenance: Fire/Life/Safety (FLS) 94% +4% 100 measures and specific color code target values. Trend status color indicators ­ identifies changes from

Webb, Peter

309

Indicators: Performance Statistics  

E-print Network

Target 1 2 3 4 5 Central Svcs. U&E Admin Preventative Maintenance: Fire/Life/Safety (FLS) 79% -8% 100 of performance measures and specific color code target values. Trend status color indicators ­ identifies changes

Webb, Peter

310

ENVIRONMENTAL PUBLIC HEALTH INDICATORS  

EPA Science Inventory

Environmental Public Health Indicators (EPHIs), quantitative measures of health factors and environmental influences tracked over time, can be used to identify specific areas and populations for intervention and prevention efforts and to evaluate the outcomes of implemented polic...

311

Dimensional stability of superinvar  

NASA Astrophysics Data System (ADS)

The unloaded dimensional stability and thermal expansivity of a single furnace melt of superinvar have been measured at room temperature using interferometric techniques. Thermal expansivity has been determined with an uncertainty of several parts in 108 per degree centigrade while dimensional stability has been determined with an uncertainty of order one part in i09 per day. Samples subjected to plastic deformation in their processing history displayed a stability improvement from 20. 5 x 1O/day to 5. 5 x 109/day and a reduction in thermal expansivity from 0. 56 x 1O/C to 0. 23 x 106/C associated with the increased mechanical work in the material. 1. MATERIAL SELECTION AND PROCESSING Modern scientific instruments place increasingly stringent demands on the dimensional stability of materials used for the construction of precision structures. The dimensional change of a material due to a change in temperature is characterized by its coefficient of thermal expansion (CTE). Dimensional changes may also occur over time in a fixed environment. In considering the selection of a material for demanding applications both the CTE and temporal stability must be considered. Indeed with reasonable control of the ambient temperature pressure humidity and magnetic field temporal instability may be the factor limiting performance. Superinvar the material studied here is one alloy in a class of materials of practical interest for the construction of precision systems. The invars are relatively inexpensive materials (by comparison other low-CTE materials) and may be fabricated using conventional metalworking techniques. Superinvar is of particular interest because it exhibits a lower CTE than the other invars and because of an early report by Jacobs Bradford and Berthold indicating that it possessed a particularly high degree of temporal stability. 1 This paper reports a series of CTE and temporal stability measurements performed on superinvar samples taken from the same melt but subjected to different degrees of processing. One of the experimental aims of this study was to learn about the conditions leading to the single high stability result reported by Jacobs. Accordingly the chemistry of the material was specified as a high purity superinvar with 31 Ni and 5 Co. This alloy lies at the minimum CTE point of the Fe-Ni-Co system2 and is the nominal alloy used by Jacobs. Table I shows the composition which was specified the analysis performed at the mill at the time of melt and an independent analysis of the material after receipt at Livermore. For reference purposes the composition of the sample measured by Jacobs is also listed. 3 The material used in the samples was cast in an air induction furnace as part of a large order. Although the same steel mill produced both this material and Jacobs'' samples the furnaces used for the two melts were different: Jacobs'' sample came from a melt in

Patterson, Steven R.

1990-11-01

312

Stabilization of eptifibatide by cosolvents.  

PubMed

Eptifibatide is a potent and highly specific inhibitor of platelet receptor glycoprotein IIb/IIIa and is indicated in the treatment of acute coronary syndrome. The commercial product Integrilin(R) (eptifibatide) Injection requires a cold/refrigerator storage condition. In an effort to improve the drug stability for room temperature storage and transportation, this study proposed a semi-aqueous formulation that contains 2 mg/ml eptifibatide, 10% ethanol, 40% propylene glycol and 50% 0.025 M citrate buffer. The stability study was conducted in the pH range 4.25-6.25 under accelerated temperatures: 48, 60, 72.5 degrees C. The results indicate that the proposed semi-aqueous vehicles substantially increased the drug stability in comparison with aqueous vehicles. The predicted drug shelf-life T(90) at 25 degrees C shows that an almost twofold increase can be achieved by formulating eptifibatide in the semi-aqueous vehicle, which is 60 months at its maximum stability of pH 5.75, as opposed to the 33 months in the aqueous vehicle at its maximum stability of pH 5.25. PMID:11337148

Zhao, L; Yalkowsky, S H

2001-05-01

313

Aircraft control position indicator  

NASA Technical Reports Server (NTRS)

An aircraft control position indicator was provided that displayed the degree of deflection of the primary flight control surfaces and the manner in which the aircraft responded. The display included a vertical elevator dot/bar graph meter display for indication whether the aircraft will pitch up or down, a horizontal aileron dot/bar graph meter display for indicating whether the aircraft will roll to the left or to the right, and a horizontal dot/bar graph meter display for indicating whether the aircraft will turn left or right. The vertical and horizontal display or displays intersect to form an up/down, left/right type display. Internal electronic display driver means received signals from transducers measuring the control surface deflections and determined the position of the meter indicators on each dot/bar graph meter display. The device allows readability at a glance, easy visual perception in sunlight or shade, near-zero lag in displaying flight control position, and is not affected by gravitational or centrifugal forces.

Dennis, Dale V. (inventor)

1987-01-01

314

Assessing asset indices.  

PubMed

The use of asset indices in welfare analysis and poverty targeting is increasing, especially in cases in which data on expenditures are unavailable or hard to collect. We compare alternative approaches to welfare measurement. Our analysis shows that inferences about inequalities in education, health care use, fertility, and child mortality, as well as labor market outcomes, are quite robust to the economic status measure used. Different measures-most significantly per capita expenditures versus the class of asset indices-do not, however, yield identical household rankings. Two factors stand out in predicting the degree of congruence in rankings. First is the extent to which expenditures can be explained by observed household and community characteristics. Rankings are most similar in settings with small transitory shocks to expenditure or with little random measurement error in expenditure. Second is the extent to which expenditures are dominated by individually consumed goods, such as food. Asset indices are typically derived from indicators of goods that are effectively public at the household level, while expenditures are often dominated by food, an almost exclusively private good. In settings in which individually consumed goods are the main component of expenditures, asset indices and per capita consumption yield the least similar results. PMID:22135117

Filmer, Deon; Scott, Kinnon

2012-02-01

315

Enhanced stability and dechlorination activity of pre-synthesis stabilized nanoscale FePd particles  

NASA Astrophysics Data System (ADS)

Nanoscale zero-valent iron (NZVI) particles are promising materials for the in-situ remediation of a wide variety of source zone contaminants. This study presents the results of a systematic investigation of the stability of bimetallic FePd nanoparticle suspensions in water and their capability to degrade trichloroethylene (TCE) synthesized in the presence of various stabilizers (i.e., carboxymethyl cellulose (CMC), polyvinylpyrrolidone (PVP), and guar gum). Results indicate a dramatic improvement in FePd suspension stability when the stabilizer is present in the matrix during the nanoparticle synthesis step. Stability enhancement is controlled by iron nanoparticle/stabilizer electrostatic and steric interactions, which are a function of the molecular structure of the stabilizer. Stabilization mechanisms differed for each stabilizer with CMC and guar gum exhibiting the best nanoparticle suspension stability improvement. Results suggest that the complexation of iron precursors with the stabilizer, during synthesis, plays a key role in nZVI stability improvement. In case of guar gum, gelation during synthesis significantly increased suspension viscosity, enhancing suspension stability. The capability of these materials to degrade TCE was also investigated. Results demonstrated that when stabilizers were present in the matrix dechlorination rates increased significantly. FePd nanoparticles in CMC had the highest observed rate constant; however the highest surface area-normalized rate constant was obtained from FePd stabilized in PVP360K. Results from this study can be used to aid in the selection of appropriate iron nanoparticle stabilizers. Stabilizer selection should be assessed on a case by case basis as no stabilizer will meet the needs of all in-situ remediation applications.

Sakulchaicharoen, Nataphan; O'Carroll, Denis M.; Herrera, Jose E.

2010-11-01

316

Enzymatic temperature change indicator  

DOEpatents

A temperature change indicator is described which is composed of an enzyme and a substrate for that enzyme suspended in a solid organic solvent or mixture of solvents as a support medium. The organic solvent or solvents are chosen so as to melt at a specific temperature or in a specific temperature range. When the temperature of the indicator is elevated above the chosen, or critical temperature, the solid organic solvent support will melt, and the enzymatic reaction will occur, producing a visually detectable product which is stable to further temperature variation.

Klibanov, Alexander M. (Newton, MA); Dordick, Jonathan S. (Iowa City, IA)

1989-01-21

317

Phenolic Compounds Profile of Cornicabra Virgin Olive Oil  

Microsoft Academic Search

This study presents the phenolic compounds profile of commercial Cornicabra virgin olive oils from five successive crop seasons (1995\\/1996 to 1999\\/2000; n ) 97), determined by solid phase extraction reversed phase high-performance liquid chromatography (SPE RP-HPLC), and its relationship with oxidative stability, processing conditions, and a preliminary study on variety classification. The median of total phenols content was 38 ppm

SERGIO GO Ä MEZ-ALONSO; DESAMPARADOS SALVADOR; GIUSEPPE FREGAPANE

318

Urban Environmental Justice Indices  

Microsoft Academic Search

Environmental justice is the principle that environmental costs and amenities ought to be equitably distributed within society. Due to the ethical, political, and public–health implications, and because many choices confront those researching environmental justice, standardized measures are needed to inform public dialogue and policy. We develop and test seven indices on three Colorado cities to measure the relationship between the

John Harner; Kee Warner; John Pierce; Tom Huber

2002-01-01

319

Rhinoplasty - indications and techniques  

PubMed Central

Rhinoplasty is considered to be one of the most challenging procedures in otolaryngology head and neck surgery. Meticulous planning and excellent surgical skills are pre-requisites for reproducible good outcomes. More than 100 years after the first rhinoplasty, many controversies regarding indication and techniques remain unresolved. The aim of this article is to review current concepts and arguments. PMID:22073085

Tasman, Abel-Jan

2008-01-01

320

Triboluminescent indicator system  

DOEpatents

There is provided a light emitting device comprising a plurality of triboluminescent particles dispersed throughout a low density, frangible body and activated by rapidly crushing the body in order to transfer mechanical energy to some portion of the particles. The light emitted by these mechanically excited particles is collected and directed into a light conduit and transmitted to a detector/indicator means.

Goods, Steven H. (Livermore, CA); Dentinger, Paul M. (Sunol, CA); Whinnery, Jr., Leroy L. (Danville, CA)

2003-06-24

321

Relative soot formation indices  

Microsoft Academic Search

The smoking tendency of a practical fuel mixture, such as a coal-derived synfuel, should be empirically predictable from sooting data on the component hydrocarbons and the mixture composition. Various parameters which have been use as relative soot threshold indicators in both premixed and diffusion flames are reviewed and their usefulness as predictors of sooting tendency briefly discussed. The effects of

1982-01-01

322

"Healthy" Human Development Indices  

ERIC Educational Resources Information Center

In the Human Development Index (HDI), life expectancy is the only indicator used in modeling the dimension "a long and healthy life". Whereas life expectancy is a direct measure of quantity of life, it is only an indirect measure of healthy years lived. In this paper we attempt to remedy this omission by introducing into the HDI the morbidity…

Engineer, Merwan; Roy, Nilanjana; Fink, Sari

2010-01-01

323

General Indicators: Performance Statistics  

E-print Network

Central Svcs. Energy Mgmt Admin Preventative Maintenance: Fire/Life/Safety (FLS) 97% +8% 100% 95% 97% 97 Chilled Utility Outages 4 +1 0 0 1 Preventative Maintenance: Fire/Life/Safety (FLS) 100% No Change 100 and specific color code target values. Trend status color indicators ­ identifies changes from the prior month

Webb, Peter

324

General Indicators: Change from  

E-print Network

Maintenance: Fire/Life/Safety (FLS) 99% No Change 100% 100% 100% 100% 98% 100% Non-FLS 91% +3% 85% 98% 98 Recent Trend Initial Target Utility Outages 1 -2 0 Preventative Maintenance: Fire/Life/Safety (FLS and specific color code target values. Trend status color indicators � identifies changes from the prior month

Webb, Peter

325

General Indicators: Change from  

E-print Network

Central Svcs. Energy Mgmt Admin Preventative Maintenance: Fire/Life/Safety (FLS) 98% +2% 100% 100% 98% 99 from Previous Month Recent Trend Initial Target Utility Outages 4 +2 0 Preventative Maintenance: Fire of performance measures and specific color code target values. Trend status color indicators ­ identifies changes

Webb, Peter

326

General Indicators: Change from  

E-print Network

Maintenance: Fire/Life/Safety (FLS) 100% No Change 100% 100% 100% 100% 100% 100% Non-FLS 95% +2% 85% 99% 97 Previous Month Recent Trend Initial Target Utility Outages 1 No Change 0 Preventative Maintenance: Fire of performance measures and specific color code target values. Trend status color indicators ­ identifies changes

Webb, Peter

327

Indicators: Change from  

E-print Network

Preventative Maintenance: Fire/Life/Safety (FLS) 87% +2% 100% 100% 100% 93% 100% 55% Non-FLS 86% -4% 85% 81% 94% Key: See Definitions Document for descriptions of performance measures and specific color code target values. Trend status color indicators ­ identifies changes from the prior month: 0 Electric 0 UNIVERSITY

Webb, Peter

328

Indicators: Change from  

E-print Network

: Fire/Life/Safety (FLS) 93% +16% 100% 100% 100% 100% 100% 40% Non-FLS 88% -1% 85% 98% 98% 90% 56% 33 Definitions Document for descriptions of performance measures and specific color code target values. Trend status color indicators ­ identifies changes from the prior month: District Breakdown Utilities: -10

Webb, Peter

329

General Indicators: Performance Statistics  

E-print Network

Svcs. Energy Mgmt Admin Preventative Maintenance: Fire/Life/Safety (FLS) 94% -2% 100% 99% 86% 99% 98 Chilled Utility Outages 1 No Change 0 1 0 Preventative Maintenance: Fire/Life/Safety (FLS) 99% -1% 100 and specific color code target values. Trend status color indicators ­ identifies changes from the prior month

Webb, Peter

330

General Indicators: Change from  

E-print Network

. Energy Mgmt Admin Preventative Maintenance: Fire/Life/Safety (FLS) 100% No Change 100% 100% 100% 100% 100 from Previous Month Recent Trend Initial Target Utility Outages 0 -1 0 Preventative Maintenance: Fire measures and specific color code target values. Trend status color indicators ­ identifies changes from

Webb, Peter

331

General Indicators: Change from  

E-print Network

Maintenance: Fire/Life/Safety (FLS) 99% -1% 100% 100% 100% 100% 99% 100% Non-FLS 94% +9% 85% 96% 99% 91% 88 Initial Target Utility Outages 1 +1 0 Preventative Maintenance: Fire/Life/Safety (FLS) 75% -25% 100% Non color code target values. Trend status color indicators ­ identifies changes from the prior month: Steam

Webb, Peter

332

General Indicators: Change from  

E-print Network

Maintenance: Fire/Life/Safety (FLS) 100% No Change 100% 100% 100% 100% 100% 100% Non-FLS 96% -1% 85% 97% 85 Initial Target Utility Outages 0 No Change 0 Preventative Maintenance: Fire/Life/Safety (FLS) 94% -2 and specific color code target values. Trend status color indicators ­ identifies changes from the prior month

Webb, Peter

333

General Indicators: Performance Statistics  

E-print Network

Science East Bank Central Svcs. Energy Mgmt Admin Preventative Maintenance: Fire/Life/Safety (FLS) 96% +11: Fire/Life/Safety (FLS) 100% +1% 100% 100% Non-FLS 94% +17% 70% 92% Key: See Definitions Document for descriptions of performance measures and specific color code target values. Trend status color indicators

Webb, Peter

334

General Indicators: Change from  

E-print Network

&E Admin Preventative Maintenance: Fire/Life/Safety (FLS) 91% +3% 100% 99% 100% 98% 100% 29% Non-FLS 94% -2% 70% Key: See Definitions Document for descriptions of performance measures and specific color code target values. Trend status color indicators ­ identifies changes from the prior month: 100% 64

Webb, Peter

335

General Indicators: Performance Statistics  

E-print Network

Central Svcs. Energy Mgmt Admin Preventative Maintenance: Fire/Life/Safety (FLS) 98% +6% 100% 98% 89% 99 Chilled Utility Outages 0 -1 0 0 0 Preventative Maintenance: Fire/Life/Safety (FLS) 100% No Change 100 and specific color code target values. Trend status color indicators ­ identifies changes from the prior month

Webb, Peter

336

General Indicators: Performance Statistics  

E-print Network

Bank Central Svcs. Energy Mgmt Admin Preventive Maintenance: Fire/Life/Safety (FLS) 85% -12% 100% 80 Trend Initial Target Steam Chilled Utility Outages 3 -5 0 1 0 Preventive Maintenance: Fire for descriptions of performance measures and specific color code target values. Trend status color indicators

Webb, Peter

337

General Indicators: Change from  

E-print Network

Maintenance: Fire/Life/Safety (FLS) 99% No Change 100% 100% 100% 100% 99% 100% Non-FLS 91% +2% 85% 97% 97 Trend Initial Target Utility Outages 2 +1 0 Preventative Maintenance: Fire/Life/Safety (FLS) 100 and specific color code target values. Trend status color indicators ­ identifies changes from the prior month

Webb, Peter

338

General Indicators: Performance Statistics  

E-print Network

Mgmt Admin Preventative Maintenance: Fire/Life/Safety (FLS) 92% -5% 100% 88% 90% 97% 100% Non-FLS 77 Utility Outages 1 -3 0 0 0 Preventative Maintenance: Fire/Life/Safety (FLS) 100% No Change 100% 100% Non color code target values. Trend status color indicators ­ identifies changes from the prior month: 92

Webb, Peter

339

General Indicators: Change from  

E-print Network

- West Health Science East Bank Central Svcs. Energy Mgmt Admin Preventative Maintenance: Fire: Fire/Life/Safety (FLS) 98% -1% 100% Non-FLS 84% -7% 70% Key: See Definitions Document for descriptions of performance measures and specific color code target values. Trend status color indicators ­ identifies changes

Webb, Peter

340

General Indicators: Change from  

E-print Network

Maintenance: Fire/Life/Safety (FLS) 100% +1% 100% 100% 100% 100% 100% 100% Non-FLS 93% +1% 85% 97% 88% 93 Month Recent Trend Initial Target Utility Outages 1 +1 0 Preventative Maintenance: Fire of performance measures and specific color code target values. Trend status color indicators ­ identifies changes

Webb, Peter

341

General Indicators: Change from  

E-print Network

Maintenance: Fire/Life/Safety (FLS) 99% +3% 100% 100% 100% 100% 98% 100% Non-FLS 90% +9% 85% 90% 92% 93% 87 Definitions Document for descriptions of performance measures and specific color code target values. Trend status color indicators ­ identifies changes from the prior month: All Districts Combined 2 Electric 1

Webb, Peter

342

General Indicators: Change from  

E-print Network

Maintenance: Fire/Life/Safety (FLS) 99% No Change 100% 99% 100% 99% 99% 100% Non-FLS 94% -1% 90% 92% 96% 98 Trend Initial Target Utility Outages 3 +3 0 Preventative Maintenance: Fire/Life/Safety (FLS) 100 and specific color code target values. Trend status color indicators ­ identifies changes from the prior month

Webb, Peter

343

General Indicators: Change from  

E-print Network

Maintenance: Fire/Life/Safety (FLS) 93% -6% 100% 100% 100% 100% 100% 83% Non-FLS 95% +1% 90% 95% 98% 97% 92% 0 Maintenance: Fire/Life/Safety (FLS) 97% -3% 100% Non-FLS 94% -2% 70% Key: See Definitions Document for descriptions of performance measures and specific color code target values. Trend status color indicators

Webb, Peter

344

General Indicators: Change from  

E-print Network

Preventative Maintenance: Fire/Life/Safety (FLS) 100% +1% 100% 100% 100% 100% 100% 100% Non-FLS 94% -1% 85 Month Recent Trend Initial Target Utility Outages 7 +7 0 Preventative Maintenance: Fire measures and specific color code target values. Trend status color indicators ­ identifies changes from

Webb, Peter

345

General Indicators: Performance Statistics  

E-print Network

Central Svcs. Energy Mgmt Admin Preventative Maintenance: Fire/Life/Safety (FLS) 85% No Change 100% 90 Trend Initial Target Steam Chilled Utility Outages 2 -1 0 0 1 Preventative Maintenance: Fire of performance measures and specific color code target values. Trend status color indicators ­ identifies changes

Webb, Peter

346

General Indicators: Change from  

E-print Network

Maintenance: Fire/Life/Safety (FLS) 100% No Change 100% 100% 100% 100% 100% 100% Non-FLS 97% +1% 85% 94% 98 Trend Initial Target Utility Outages 2 +2 0 Preventative Maintenance: Fire/Life/Safety (FLS) 100% +6 and specific color code target values. Trend status color indicators ­ identifies changes from the prior month

Webb, Peter

347

General Indicators: Performance Statistics  

E-print Network

Central Svcs. Energy Mgmt Admin Preventative Maintenance: Fire/Life/Safety (FLS) 85% -13% 100% 94% 98% 62 Chilled Utility Outages 3 +3 0 0 2 Preventative Maintenance: Fire/Life/Safety (FLS) 100% No Change 100 and specific color code target values. Trend status color indicators ­ identifies changes from the prior month

Webb, Peter

348

General Indicators: Change from  

E-print Network

Maintenance: Fire/Life/Safety (FLS) 100% No Change 100% 100% 100% 100% 100% 100% Non-FLS 97% +2% 85% 97% 99: Fire/Life/Safety (FLS) 96% -4% 100% Non-FLS 100% No Change 70% Key: See Definitions Document for descriptions of performance measures and specific color code target values. Trend status color indicators

Webb, Peter

349

General Indicators: Performance Statistics  

E-print Network

Health Science East Bank Central Svcs. Energy Mgmt Admin Preventative Maintenance: Fire/Life/Safety (FLS Chilled Utility Outages 3 -2 0 1 0 Preventative Maintenance: Fire/Life/Safety (FLS) 100% No Change 100 and specific color code target values. Trend status color indicators ­ identifies changes from the prior month

Webb, Peter

350

General Indicators: Performance Statistics  

E-print Network

Science East Bank Central Svcs. Energy Mgmt Admin Preventative Maintenance: Fire/Life/Safety (FLS) 91% -3 Maintenance: Fire/Life/Safety (FLS) 100% +1% 100% 100% Non-FLS 78% +8% 70% 75% Key: See Definitions Document for descriptions of performance measures and specific color code target values. Trend status color indicators

Webb, Peter

351

General Indicators: Change from  

E-print Network

- West Health Science East Bank Central Svcs. U&E Admin Preventative Maintenance: Fire/Life/Safety (FLS% -12% 70% Key: See Definitions Document for descriptions of performance measures and specific color code target values. Trend status color indicators ­ identifies changes from the prior month: 100% 63

Webb, Peter

352

General Indicators: Change from  

E-print Network

Preventative Maintenance: Fire/Life/Safety (FLS) 99% +1% 100% 100% 100% 100% 98% 99% Non-FLS 95% +7% 85% 96 Trend Initial Target Utility Outages 0 -2 0 Preventative Maintenance: Fire/Life/Safety (FLS) 100 and specific color code target values. Trend status color indicators ­ identifies changes from the prior month

Webb, Peter

353

General Indicators: Change from  

E-print Network

Maintenance: Fire/Life/Safety (FLS) 99% -1% 100% 100% 100% 100% 99% 95% Non-FLS 95% -2% 85% 99% 95% 93% 95 Trend Initial Target Utility Outages 0 -2 0 Preventative Maintenance: Fire/Life/Safety (FLS) 100 measures and specific color code target values. Trend status color indicators ­ identifies changes from

Webb, Peter

354

General Indicators: Performance Statistics  

E-print Network

Bank Central Svcs. Energy Mgmt Admin Preventive Maintenance: Fire/Life/Safety (FLS) 87% -4% 100% 47 Trend Initial Target Steam Chilled Utility Outages 2 +1% 0 0 0 Preventive Maintenance: Fire for descriptions of performance measures and specific color code target values. Trend status color indicators

Webb, Peter

355

General Indicators: Change from  

E-print Network

Mgmt Admin Preventative Maintenance: Fire/Life/Safety (FLS) 99% +1% 100% 100% 100% 95% 100% 100% Non Recent Trend Initial Target Chilled Utility Outages 1 -3 0 1 Preventative Maintenance: Fire of performance measures and specific color code target values. Trend status color indicators ­ identifies changes

Webb, Peter

356

General Indicators: Performance Statistics  

E-print Network

. Energy Mgmt Admin Preventive Maintenance: Fire/Life/Safety (FLS) 97% +10% 100% 96% 93% 99% 98% Non Chilled Utility Outages 8 +6% 0 1 2 Preventive Maintenance: Fire/Life/Safety (FLS) 100% No Change 100 and specific color code target values. Trend status color indicators ­ identifies changes from the prior month

Webb, Peter

357

General Indicators: Change from  

E-print Network

Maintenance: Fire/Life/Safety (FLS) 96% +3% 100% 100% 100% 100% 99% 87% Non-FLS 97% +2% 90% 99% 97% 95% 96 Maintenance: Fire/Life/Safety (FLS) 99% +2% 100% Non-FLS 94% No Change 70% Key: See Definitions Document for descriptions of performance measures and specific color code target values. Trend status color indicators

Webb, Peter

358

Indicators: Change from  

E-print Network

: Fire/Life/Safety (FLS) 77% -13% 100% 100% 100% 99% 97% 32% Non-FLS 89% +3% 85% 96% 98% 92% 49% 33 Definitions Document for descriptions of performance measures and specific color code target values. Trend status color indicators ­ identifies changes from the prior month: 1 Electric 0 UNIVERSITY SERVICES

Webb, Peter

359

General Indicators: Change from  

E-print Network

: Fire/Life/Safety (FLS) 99% -1% 100% 99% 100% 100% 99% 100% Non-FLS 92% -2% 85% 94% 96% 93% 85% 100 Previous Month Recent Trend Initial Target Utility Outages 0 -7 0 Preventative Maintenance: Fire measures and specific color code target values. Trend status color indicators ­ identifies changes from

Webb, Peter

360

Universal Indicator Rainbow Trout  

NSDL National Science Digital Library

In this activity on page 2 of the PDF, learners discover how color changes can help scientists distinguish between acids and bases. Learners create colorful rainbow trout artwork using universal indicator solution and various household liquids. Safety note: learners must wear safety goggles.

Society, American C.

2001-01-01

361

Indications for Fetal Echocardiography  

Microsoft Academic Search

Congenital heart disease is one of the most common congenital malformations diagnosed in liveborns. As more women undergo prenatal diagnosis, the need for screening fetal echocadiography increases. The fetal, maternal, and familial indications for fetal echocadiography are outlined in order to improve the identification of women in greatest need for this screening modality.

M. Small; J. A. Copel

2004-01-01

362

Landscape-based Indicators  

EPA Science Inventory

The report is based on data and experience gained through the GLNPO-funded Great Lakes Coastal Wetland Consortium (GLCWC) and the EPA-STAR funded Great Lakes Ecological Indicators Project (GLEI). EPA-MED author Trebitz and other MED personnel were collaborators on the GLEI proje...

363

Trends & Indicators: Enrollment Period  

ERIC Educational Resources Information Center

Since New England Board of Higher Education (NEBHE) began publishing tables and charts exploring "Trends & Indicators" in New England higher education more than a half-century ago, few figures have grabbed as much attention as college "enrollment" data. These local, state, regional and national data go beyond simple headcounts of students going to…

Harney, John O.

2011-01-01

364

Protein Stability in Ice  

PubMed Central

This study presents an experimental approach, based on the change of Trp fluorescence between native and denatured states of proteins, which permits to monitor unfolding equilibria and the thermodynamic stability (?G°) of these macromolecules in frozen aqueous solutions. The results obtained by guanidinium chloride denaturation of the azurin mutant C112S from Pseudomonas aeruginosa, in the temperature range from ?8 to ?16°C, demonstrate that the stability of the native fold may be significantly perturbed in ice depending mainly on the size of the liquid water pool (VL) in equilibrium with the solid phase. The data establish a threshold, around VL = 1.5%, below which in ice ?G° decreases progressively relative to liquid state, up to 3 kcal/mole for VL = 0.285%. The sharp dependence of ?G° on VL is consistent with a mechanism based on adsorption of the protein to the ice surface. The reduction in ?G° is accompanied by a corresponding decrease in m-value indicating that protein-ice interactions increase the solvent accessible surface area of the native fold or reduce that of the denatured state, or both. The method opens the possibility for examining in a more quantitative fashion the influence of various experimental conditions on the ice perturbation and in particular to test the effectiveness of numerous additives used in formulations to preserve labile pharmaco proteins. PMID:17189314

Strambini, Giovanni B.; Gonnelli, Margherita

2007-01-01

365

LEADING WITH LEADING INDICATORS  

SciTech Connect

This paper documents Fluor Hanford's use of Leading Indicators, management leadership, and statistical methodology in order to improve safe performance of work. By applying these methods, Fluor Hanford achieved a significant reduction in injury rates in 2003 and 2004, and the improvement continues today. The integration of data, leadership, and teamwork pays off with improved safety performance and credibility with the customer. The use of Statistical Process Control, Pareto Charts, and Systems Thinking and their effect on management decisions and employee involvement are discussed. Included are practical examples of choosing leading indicators. A statistically based color coded dashboard presentation system methodology is provided. These tools, management theories and methods, coupled with involved leadership and employee efforts, directly led to significant improvements in worker safety and health, and environmental protection and restoration at one of the nation's largest nuclear cleanup sites.

PREVETTE, S.S.

2005-01-27

366

Health Care Indicators  

PubMed Central

This regular feature of the journal includes a discussion of each of the following four topics: community hospital statistics; employment, hours, and earnings in the private health sector; health care prices; and national economic indicators. These statistics are valuable in their own right for understanding the relationship between the health care sector and the overall economy. In addition, they allow us to anticipate the direction and magnitude of health care cost changes prior to the availability of more comprehensive data. PMID:25372574

Donham, Carolyn S.; Maple, Brenda T.; Letsch, Suzanne W.

1993-01-01

367

Industrial energy use indices  

E-print Network

.1 to 1.7 depending on the energy sources considered. The large data scatter indicates that predictions of energy use obtained by multiplying standard EUI data by plant area may be inaccurate and are less accurate in warmer than colder climates (warmer... and colder are determined by annual average temperature weather data). Data scatter may have several explanations, including climate, plant area accounting, the influence of low cost energy and low cost buildings used in the south of the U.S. iv...

Hanegan, Andrew Aaron

2008-10-10

368

Workshop on Feedback Stabilization of MHD Stabilities  

SciTech Connect

The feedback stabilization of MHD instabilities is an area of research that is critical for improving the performance and economic attractiveness of magnetic confinement devices. A Workshop dedicated to feedback stabilization of MHD instabilities was held from December 11-13, 1996 at the Princeton Plasma Physics Laboratory, Princeton NJ, USA. The resulting presentations, conclusions, and recommendations are summarized.

McGuire, K.; Kugel, H. [Princeton Univ., NJ (United States). Plasma Physics Lab.; La Haye, R. [General Atomics, San Diego, CA (United States); Mauel, M. [Columbia Univ., New York, NY (United States). Dept. of Applied Physics; Nevins, W. [Lawrence Livermore National Lab., CA (United States); Prager, S. [Wisconsin Univ., Madison, WI (United States). Dept. of Physics

1996-12-31

369

Tamper indicating packaging  

SciTech Connect

Protecting sensitive items from undetected tampering in an unattended environment is crucial to the success of non-proliferation efforts relying on the verification of critical activities. Tamper Indicating Packaging (TIP) technologies are applied to containers, packages, and equipment that require an indication of a tamper attempt. Examples include: the transportation and storage of nuclear material, the operation and shipment of surveillance equipment and monitoring sensors, and the retail storage of medicine and food products. The spectrum of adversarial tampering ranges from attempted concealment of a pin-hole sized penetration to the complete container replacement, which would involve counterfeiting efforts of various degrees. Sandia National Laboratories (SNL) has developed a technology base for advanced TIP materials, sensors, designs, and processes which can be adapted to various future monitoring systems. The purpose of this technology base is to investigate potential new technologies, and to perform basic research of advanced technologies. This paper will describe the theory of TIP technologies and recent investigations of TIP technologies at SNL.

Baumann, M.J.; Bartberger, J.C.; Welch, T.D.

1994-08-01

370

The Boston Indicators Project  

NSDL National Science Digital Library

Coordinated by the partnership of the City of Boston, the Metropolitan Area Planning Council, and the Boston Foundation, the Boston Indicators Project "aims to democratize access to information, foster informed public discourse, track progress on shared civic goals, and report on change in 10 sectors: Civic Vitality, Cultural Life and the Arts, the Economy, Education, the Environment, Health, Housing, Public Safety, Technology, and Transportation." Visitors to the site can review the Project's most recent report as well as past versions. At the top of the page, there are various sections to visit, which cover the 10 sectors mentioned above. In each of these sections, visitors can read a brief summary, view highlights within each sector, read about the goals and measures of each sector, and find related links to research, resources, and news for each sector. The website also includes the feature "The Hub of Innovation" which highlights some of the most forward-looking local, regional, national and international work in the ten sectors tracked by the Boston Indicators Project.

371

Trust in performance indicators?  

PubMed Central

The 1980s and 90s have seen the proliferation of all forms of performance indicators as part of attempts to command and control health services. The latest area to receive attention is health outcomes. Published league tables of mortality and other health outcomes have been available in the United States for some time and in Scotland since the early 1990s; they have now been developed for England and Wales. Publication of these data has proceeded despite warnings as to their limited meaningfulness and usefulness. The time has come to ask whether the remedy is worse than the malady: are published health outcomes contributing to quality efforts or subverting more constructive approaches? This paper argues that attempts to force improvements through publishing health outcomes can be counterproductive, and outlines an alternative approach which involves fostering greater trust in professionalism as a basis for quality enhancements. PMID:10185142

Davies, H. T.; Lampel, J.

1998-01-01

372

Effect of adding free amino acids to Cheddar cheese curd on proteolysis, flavour and texture development  

Microsoft Academic Search

Cheddar cheeses were supplemented with cas-amino acids (0–63mmol kg?1) during manufacture. Flavour, texture and proteolysis were monitored over a 6-month ripening period. Polyacrylamide gel electrophoresis indicated no differences in proteolysis between experimental and control cheeses. RP-HPLC indicated only minor qualitative differences between the cheeses; however, a higher level of all peptides was evident in cheeses with intermediate levels (21–42mmol kg?1)

J. M. Wallace; P. F. Fox

1997-01-01

373

Precipitation Indices Low Countries  

NASA Astrophysics Data System (ADS)

Since 1995, KNMI published a series of books(1), presenting an annual reconstruction of weather and climate in the Low Countries, covering the period AD 763-present, or roughly, the last millennium. The reconstructions are based on the interpretation of documentary sources predominantly and comparison with other proxies and instrumental observations. The series also comprises a number of classifications. Amongst them annual classifications for winter and summer temperature and for winter and summer dryness-wetness. The classification of temperature have been reworked into peer reviewed (2) series (AD 1000-present) of seasonal temperatures and temperature indices, the so called LCT (Low Countries Temperature) series, now incorporated in the Millennium databases. Recently we started a study to convert the dryness-wetness classifications into a series of precipitation; the so called LCP (Low Countries Precipitation) series. A brief outline is given here of the applied methodology and preliminary results. The WMO definition for meteorological drought has been followed being that a period is called wet respectively dry when the amount of precipitation is considerable more respectively less than usual (normal). To gain a more quantitative insight for four locations, geographically spread over the Low Countries area (De Bilt, Vlissingen, Maastricht and Uccle), we analysed the statistics of daily precipitation series, covering the period 1900-present. This brought us to the following definition, valid for the Low Countries: A period is considered as (very) dry respectively (very) wet if over a continuous period of at least 60 days (~two months) cq 90 days (~three months) on at least two out of the four locations 50% less resp. 50% more than the normal amount for the location (based on the 1961-1990 normal period) has been measured. This results into the following classification into five drought classes hat could be applied to non instrumental observations: Very wet period (+2): Wide scale river flooding, marshy acres and meadows.-Farmers cope with poor harvests of hay, grains, fruit etc. resulting in famines.-Late grape harvests, poor yield quantity and quality of wine. Wet period (+1): High water levels cq discharges of major rivers, tributaries and brooks, local river floodings, marshy acres and meadows in the low lying areas.-Wearisome and hampered agriculture. Normal (0) Dry period (-1): Low water levels cq discharges of major rivers, tributaries and brooks. Some brooks may dry up.-Summer half year: local short of yield of grass, hay and other forage.-Summer half year: moor-, peat- and forest fires. Very dry period (-2): Very low water levels cq discharges of major rivers and tributaries. Brooks and wells dry up. Serious shortage of drinking water; especially in summer.-Major agricultural damage, shortage of water, mortality stock of cattle. Shortage of grain. Flour can not be produced due to water mills running out of water, shortage of bread, bread riots, famines.-Large scale forest and peat areas, resulting in serious air pollution. Town fires. By verifying the historical evidence on these criterions, a series of 5 step indices ranging from very dry to very wet for summer and winter half year of the Low Countries was obtained. Subsequently these indices series were compared with the instrumentally observed seasonal precipitation sums for De Bilt (1735-2008), which is considered to be representative for the Central Netherlands. For winter (Oct-March) and summer half year (Apr.-Sept.) the accumulated precipitation amounts are calculated; these amounts are approximately normally distributed. Based on this distribution, the cumulative frequency distribution is calculated. By tabulating the number of summers in the pre-instrumental period 1201-1750 for each of the drought classes, a distribution is calculated which is then related to the modern accumulated precipitation distribution. Assuming that the accumulated precipitation amount has not been below (above) the mean precipitation minus (plus) three standard deviations for

van Engelen, A. F. V.; Ynsen, F.; Buisman, J.; van der Schrier, G.

2009-09-01

374

High-performance liquid chromatography coupled with mass spectrometry for analysis of ultrasmall palladium nanoparticles.  

PubMed

Metal nanoparticles (NPs) have recently attracted considerable attention in many areas of research including bioscience, chemistry and material science. Regrettably, most current and past work usually focuses on studies of multi-component NPs mixture where there is a plethora of NPs species co-existing. This work highlights the merits of reverse-phase high-performance liquid chromatography (RP-HPLC) for disclosing the genuine properties of individual palladium nanoparticles (PdNPs) species present in an as-synthesized N,N'-dimethylformamide-stabilized PdNPs product (DMF-PdNPs) which might have been previously hidden or misinterpreted. DMF-PdNPs is successfully separated by RP-HPLC that smaller DMF-PdNPs are approximately eluted first and then follow by the large ones on a C18 column. The separation fractions are further collected and determined their chemical compositions by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The results unambiguously reveal that the as-synthesized DMF-PdNPs product is indeed a complex mixture of ultrasmall PdxNPs (x=10-20) stabilized with different numbers of DMF ligands. It is anticipated that the separated fractions afforded by RP-HPLC will offer more accurate determinations of the catalytic, electronic, optical and toxicological properties of metal NPs which might have been previously misinterpreted. PMID:25281151

Zhang, Lei; Li, Zhongping; Zhang, Yan; Chin Paau, Man; Hu, Qin; Gong, Xiaojuan; Shuang, Shaomin; Dong, Chuan; Peng, Xiaoguang; Choi, Martin M F

2015-01-01

375

Automatic Stability of Airplanes  

NASA Technical Reports Server (NTRS)

It is endeavored in this report to give a full outline of the problem of airplane stability and to classify the proposed solutions systematically. Longitudinal stability, which can be studied separately, is considered first. The combination of lateral and directional stabilities, which cannot be separated, will be dealt with later.

Haus, FR

1932-01-01

376

Food Fortification Stability Study  

NASA Technical Reports Server (NTRS)

NASA has established the goal of traveling beyond low-Earth orbit and extending manned exploration to Mars. The extended length of a Mars mission, along with the lack of resupply missions increases the importance of nutritional content in the food system. The purpose of this research is to assess the stability of vitamin supplementation in traditionally processed spaceflight foods. It is expected that commercially available fortificants will remain stable through long-duration missions if proper formulation, processing, and storage temperatures are all achieved. Five vitamins (vitamin E, vitamin K, pantothenic acid, folic acid, and thiamin) were blended into a vitamin premix (DSM, Freeport, TX); premixes were formulated to be compatible with current processing techniques (retort or freeze-dried), varied water activities (high or low), and packaging material. The overall goal of this process is to provide 25% of the recommended daily intake of each vitamin (per serving), following processing and two years of ambient storage. Four freeze-dried foods (Scrambled Eggs, Italian Vegetables, Potatoes Au Gratin, Noodles and Chicken) and four thermostabilized foods (Curry Sauce with Vegetables, Chicken Noodle Soup, Grilled Pork Chop, Rice with Butter) were produced (with and without the vitamin premix), to assess the impact of the added fortificant on color and taste, and to determine the stability of supplemental vitamins in spaceflight foods. The use of fortification in spaceflight foods appears to be a plausible mitigation step to inadequate nutrition. This is due to the ease of vitamin addition as well as the sustainability of the premixes through initial processing steps. Postprocessing analysis indicated that vitamin fortification with this premix did not immediately impact organoleptic properties of the food. At this stage, the largest hurdle to fortification is the preciseness to which vitamins can be added; the total amount of vitamins required for production is 10 - 20 grams, a minor percentage of the formulation. As demonstrated by the over-fortification measured in Italian Vegetables and Grilled Pork Chop, homogeneity may be difficult to achieve with such small amounts. Thus, pouch-to-pouch variability, over-fortification, and underfortification may ensue if a method for precise addition is not identified. Stability will continue to be evaluated over two years of storage at three temperatures, and future analysis should reveal the extent to which this issue should be a concern

Abdulmalik, T. O.; Cooper, M. R.; Douglas, G. L.

2015-01-01

377

A global indicator for biological invasion.  

PubMed

"Trends in invasive alien species" is one of only two indicators of threat to biodiversity that form part of the Convention on Biological Diversity's (CBD) framework for monitoring progress toward its "2010 target" (i.e., the commitment to achieve by 2010 a significant reduction in the current rate of biodiversity loss). To date, however, there is no fully developed indicator for invasive alien species (IAS) that combines trends, derived from a standard set of methods, across species groups, ecosystems, and regions. Here we provide a rationale for the form and characteristics of an indicator of trends in IAS that will meet the 2010 framework goal and targets for this indicator. We suggest single and composite indicators that include problem-status and management-status measures that are designed to be flexible, readily disaggregated, and as far as possible draw on existing data. The single indicators at national and global scales are number of IAS and numbers of operational management plans for IAS. Global trends in IAS are measured as the progress of nations toward the targets of stabilizing IAS numbers and the implementation of IAS management plans. The proposed global indicator thus represents a minimum information set that most directly addresses the indicator objective and simultaneously aims to maximize national participation. This global indicator now requires testing to assess its accuracy, sensitivity, and tractability. Although it may not be possible to achieve the desired objective for a global indicator of biological invasion by 2010 as comprehensively as desired, it seems possible to obtain trend estimates for a component of the taxa, ecosystems, and regions involved. Importantly, current indicator development initiatives will also contribute to developing the mechanisms necessary for monitoring global trends in IAS beyond 2010. PMID:17181799

McGeoch, Melodie A; Chown, Steven L; Kalwij, Jesse M

2006-12-01

378

Feedback stabilization initiative  

SciTech Connect

Much progress has been made in attaining high confinement regimes in magnetic confinement devices. These operating modes tend to be transient, however, due to the onset of MHD instabilities, and their stabilization is critical for improved performance at steady state. This report describes the Feedback Stabilization Initiative (FSI), a broad-based, multi-institutional effort to develop and implement methods for raising the achievable plasma betas through active MHD feedback stabilization. A key element in this proposed effort is the Feedback Stabilization Experiment (FSX), a medium-sized, national facility that would be specifically dedicated to demonstrating beta improvement in reactor relevant plasmas by using a variety of MHD feedback stabilization schemes.

NONE

1997-06-01

379

On practical stability.  

NASA Technical Reports Server (NTRS)

In this paper, a class of nonlinear nonautonomous systems with multiple nonlinearities is considered. Sufficient conditions are developed for a type of practical stability with specified settling time. The conditions are independent of the actual form of nonlinear characteristics so that they can be interpreted as conditions for 'absolute' practical stability. The stability test is reduced to verification of the Hurwitz property of a constant matrix. This makes the stability analysis of the considered class of nonlinear systems convenient for machine computations. The proposed practical stability analysis is applied to a third-order system with several nonlinearities.

Grujic, L. T.

1972-01-01

380

Posterior dynamic stabilization systems: DYNESYS.  

PubMed

Posterior dynamic stabilization systems have to neutralize injurious forces and restore painless function of the spine segments and protect the adjacent segments. Because degenerative disc disease has many clinical manifestations, pedicular screw systems and interspinous implants have their indications. A dynamic stabilization device has to provide stability throughout its lifetime, unless it activates or allows reparative processes with a reversal of the degenerative changes. Anchorage to the bone is crucial, at least for pedicular systems. This is a great demand on spinal implants and assumes rest and motion going together. Our experience with DYNESYS has shown that this method has limitations in elderly patients with osteoporotic bone or in patients with a severe segmental macro-instability combined with degenerative olisthesis and advanced disc degeneration. Such cases have an increased risk of failure. Only future randomized evaluations will be able to address the potential reduction of accelerated adjacent segment degeneration. The few posterior dynamic stabilization systems that have had clinical applications so far have produced clinical outcomes comparable with fusion. No severe adverse events caused by these implants have been reported. Long-term follow-up data and controlled prospective randomized studies are not available for most of the cited implants but are essential to prove the safety, efficacy, appropriateness, and economic viability of these methods. PMID:15950696

Schwarzenbach, Othmar; Berlemann, Ulrich; Stoll, Thomas M; Dubois, Gilles

2005-07-01

381

The Effects of Religious Homogamy on Marital Satisfaction and Stability  

Microsoft Academic Search

Previous studies have indicated a relationship between religious homogamy and marital satisfaction and stability. However, most have emphasized denominational affiliation only. Using loglinear analysis of national survey data, this study tested the effects of three types of religious homogamy - namely denominational affiliation, church attendance, and belief in the Bible - upon marital satisfaction and stability. Results indicated that denominational

Timothy B. Heaton; EDITH L. PRATT

1990-01-01

382

Indications and limitations of splints and casts.  

PubMed

Long bone fractures are relatively common in cattle, whether they result from a self-inflicted trauma or from external actors (herd mate or farm machinery). Various advanced orthopedic techniques have been described to stabilize and treat fractures in cattle with success. Unfortunately the use of most of those techniques remains unrealistic in a field setting, rendering the realization of splints and casts still accurate for the treatment of long bone fracture in cattle. This article refers to the use of all external coaptation and their specific indications as well as their limitations. PMID:24534659

Mulon, Pierre-Yves; Desrochers, André

2014-03-01

383

Aerodynamic Stabilization of Flexible Optical Disk with Triangularly Arranged Stabilizer System  

NASA Astrophysics Data System (ADS)

We have developed a flexible optical disk (FOD) system comprising a flexible disk and stabilizer, which can achieve a small axial runout of the disk through simplified stabilizer control. The approach adopts a new stabilizer system made up of triangularly arranged stabilizers (TASs), which consists of one main stabilizer (MS) that stabilizes the pickup focus area on the disk and two auxiliary stabilizers (ASs) that control the balancing conditions around the MS. We experimentally demonstrated that the TAS system could effectively stabilize a flexible disk even under conditions with no active stabilizer adjustments, such as axial position control and tilt control, which could not be eliminated in our previous single-stabilizer system. The suppressed axial runout without active adjustments was sufficiently small of less than 5 ?m at linear velocities from 5.7 to 13.0 m/s up to double the speed of Blu-ray disk system. The results indicated that the FOD system with the TASs, which is easily operated, could be implemented in high-density optical disk systems with a high numerical-aperture (NA) pickup.

Aman, Yasutomo; Onagi, Nobuaki; Murata, Shozo; Uchida, Keisuke

2005-05-01

384

Purification and identification of antioxidant peptides from walnut (Juglans regia L.) protein hydrolysates.  

PubMed

Walnut proteins were hydrolyzed separately using three different proteases to obtain antioxidant peptides. The antioxidant activities of the hydrolysates were measured using 1,1-diphenyl-2-picryl hydrazyl (DPPH) assay. Among hydrolysates, pepsin hydrolysate obtained by 3h exhibited the highest antioxidant activities, which could also quench the hydroxyl radical, chelate ferrous ion, exhibit reducing power and inhibit the lipid peroxidation. Then, 3-h pepsin hydrolysates were purified sequentially by ultrafiltration, gel filtration and RP-HPLC. The sequence of the peptide with the highest antioxidative activity was identified to be Ala-Asp-Ala-Phe (423.23 Da) using RP-HPLC-ESI-MS, which was identified for the first time from walnut protein hydrolysates. Last, the inhibition of the peptide on lipid peroxidation was similar with that of reduced glutathione (GSH). These results indicate that the protein hydrolysates and/or its isolated peptides may be effectively used as food additives. PMID:23022588

Chen, Ning; Yang, Hongmei; Sun, Yi; Niu, Jun; Liu, Shuying

2012-12-01

385

Development and application of a reversed-phase high-performance liquid chromatographic method for quantitation and characterization of a Chikungunya virus-like particle vaccine.  

PubMed

To effectively support the development of a Chikungunya (CHIKV) virus-like particle (VLP) vaccine, a sensitive and robust high-performance liquid chromatography (HPLC) method that can quantitate CHIKV VLPs and monitor product purity throughout the manufacturing process is needed. We developed a sensitive reversed-phase HPLC (RP-HPLC) method that separates capsid, E1, and E2 proteins in CHIKV VLP vaccine with good resolution. Each protein component was verified by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-ToF) mass spectrometry (MS). The post-translational modifications on the viral glycoproteins E1 and E2 were further identified by intact protein mass measurements with liquid chromatography-mass spectrometry (LC-MS). The RP-HPLC method has a linear range of 0.51-12?g protein, an accuracy of 96-106% and a precision of 12% RSD, suitable for vaccine product release testing. In addition, we demonstrated that the RP-HPLC method is useful for characterizing viral glycoprotein post-translational modifications, monitoring product purity during process development and assessing product stability during formulation development. PMID:25234500

Shytuhina, Anastasija; Pristatsky, Pavlo; He, Jian; Casimiro, Danilo R; Schwartz, Richard M; Hoang, Van M; Ha, Sha

2014-10-17

386

Stability of holographic superconductors  

SciTech Connect

We study the dynamical stability of holographic superconductors. We first classify perturbations around black hole background solutions into vector and scalar sectors by means of a 2-dimensional rotational symmetry. We prove the stability of the vector sector by explicitly constructing the positive definite Hamiltonian. To reveal a mechanism for the stabilization of a superconducting phase, we construct a quadratic action for the scalar sector. From the action, we see the stability of black holes near a critical point is determined by the equation of motion for a charged scalar field. We show the effective mass of the charged scalar field in hairy black holes is always above the Breitenlohner-Freedman bound near the critical point due to the backreaction of a gauge field. It implies the stability of the superconducting phase. We also argue that the stability continues away from the critical point.

Kanno, Sugumi [Centre for Particle Theory, Department of Mathematical Sciences, Durham University, Science Laboratories, South Road, Durham, DH1 3LE (United Kingdom); Soda, Jiro [Department of Physics, Kyoto University, Kyoto, 606-8501 (Japan)

2010-10-15

387

Science and Engineering Indicators--1996  

NSF Publications Database

S&EScience and Engineering Indicators - 1996This report is available in hypertext and Portable ... Indicators 1996Portable Document Format (.pdf)Science & Engineering Indicators 1996U.S. Science and ...

388

Science and Engineering Indicators: 1996  

NSF Publications Database

Science and Engineering Indicators - 1996This report is available in hypertext and Portable Document ... Indicators 1996Portable Document Format (.pdf)Science & Engineering Indicators 1996U.S. Science and ...

389

Physical stability of insulin formulations.  

PubMed

Insulin aggregation remains a fundamental obstacle to the long-term application of many insulin infusion systems. We here report the effects of physiologic and nonphysiologic compounds on the aggregation behavior of crystalline zinc insulin (CZI) solutions. Under conditions chosen to simulate the most severe that would be encountered in delivery systems (presence of air, continuous motion, and elevated temperature), both highly purified and regular CZI at 5 U/ml formed turbid gels in 5 days. At concentrations of 100 and 500 U/ml stability was increased with turbid gels forming at 12 and 15 days, respectively. Under identical conditions, 5 U/ml CZI formulations containing the physiologic surfactant lysophosphatidylcholine (0.02%) or the synthetic surfactants SDS (1%), Brij 35 (0.1%), Tween (0.01%), or Triton X (0.01%) retained a transmittance at 540 nm of greater than 96% for 67-150 days. These nonionic and ionic surfactants containing the hydrophobic group, CH3(CH2)N, with N = 7-16, remarkably stabilized CZI formulations while those lacking such groups demonstrated little or no effect. The alcohols glycerol (30-50%) and isopropanol (10-50%) were moderately effective stabilizers. Silicone rubber drastically accelerated aggregation in all but one formulation (1% SDS). Emphasis in this study was placed on the properties of 5-U/ml formulations. Controls run at higher concentrations indicated a positive correlation between concentration and stability. It was concluded that the aggregation of insulin into high-molecular-weight polymers may be inhibited by reducing the effective polarity of the solvent. In this regard, anionic and nonionic surfactants containing appropriately long hydrophobic groups demonstrated the greatest degree of stabilization. Finally, of all the medical grade materials likely to be used in pumps, silicone rubber is the most active in promoting insulin aggregation. PMID:6341125

Lougheed, W D; Albisser, A M; Martindale, H M; Chow, J C; Clement, J R

1983-05-01

390

Stabilizing Grout Compatibility Study  

SciTech Connect

This report provides data that will be used to formulate the stabilizing grout and includes experimental results for Tc-99 stabilization by two reagents, (1) ground granulated blast furnace slag (GGBFS) and (2) surface treated hydroxyapatite (HA). One or both of these reagents are being considered by CH2M HILL for incorporation in the binder portion (matrix portion without sand) of the stabilizing grout. The technical basis for identifying the grout ingredient(s) for stabilizing technetium (Tc-99) will be provided by researchers at the Savannah River Technology Center (SRTC) in a subsequent report.

HARBOUR, JOHNR.

2004-05-19

391

Vorton existence and stability.  

PubMed

We present the first concrete evidence for the classical stability of vortons, circular cosmic string loops stabilized by the angular momentum of the charge and current trapped on the string. We begin by summarizing what is known about vorton solutions and, in particular, their analytic stability with respect to a range of radial and nonradial perturbations. We then discuss numerical results of vorton simulations in a full 3D field theory, that is, Witten's original bosonic superconducting string model with a modified potential term. For specific parameter values, these simulations demonstrate the long-term stability of sufficiently large vorton solutions created with an elliptical initial ansatz. PMID:14611514

Lemperiere, Y; Shellard, E P S

2003-10-01

392

Science and Engineering Indicators: 1993  

NSF Publications Database

Science & Science & Engineering Indicators '93 provides a comprehensive overview of the science ... The hypertext version of the Science & Engineering Indicators '93 was developed under contract to ...

393

Illustrating Chemiluminescence with Siloxene Indicator.  

ERIC Educational Resources Information Center

Discusses the nature of light-producing reactions and provides a procedure for demonstrating chemical luminescence using siloxene indicator. Indicates source of this chemical and safety precautions. (SK)

Hoff, Ray

1981-01-01

394

Should researchers use single indicators, best indicators, or multiple indicators in structural equation models?  

PubMed Central

Background Structural equation modeling developed as a statistical melding of path analysis and factor analysis that obscured a fundamental tension between a factor preference for multiple indicators and path modeling’s openness to fewer indicators. Discussion Multiple indicators hamper theory by unnecessarily restricting the number of modeled latents. Using the few best indicators – possibly even the single best indicator of each latent – encourages development of theoretically sophisticated models. Additional latent variables permit stronger statistical control of potential confounders, and encourage detailed investigation of mediating causal mechanisms. Summary We recommend the use of the few best indicators. One or two indicators are often sufficient, but three indicators may occasionally be helpful. More than three indicators are rarely warranted because additional redundant indicators provide less research benefit than single indicators of additional latent variables. Scales created from multiple indicators can introduce additional problems, and are prone to being less desirable than either single or multiple indicators. PMID:23088287

2012-01-01

395

Thermal stability of an interface-stabilized skyrmion lattice.  

PubMed

The thermal stability of the magnetic nano-skyrmion lattice in the monolayer Fe/Ir(111) is investigated using temperature dependent spin-polarized scanning tunneling microscopy. Our experiments show that the skyrmion lattice disappears at a temperature of T_{c}=27.8??K, indicating a loss of long-range magnetic order. At second-layer iron islands the lattice is pinned and local order persists at temperatures above T_{c}. The findings are explained in terms of the complex magnetic interactions involved in the formation of the skyrmion lattice. PMID:25170729

Sonntag, A; Hermenau, J; Krause, S; Wiesendanger, R

2014-08-15

396

Derivation of lake mixing and stratification indices from high-resolution lake buoy data  

Microsoft Academic Search

Lake Analyzer is a numerical code coupled with supporting visualization tools for determining indices of mixing and stratification that are critical to the biogeochemical cycles of lakes and reservoirs. Stability indices, including Lake Number, Wedderburn Number, Schmidt Stability, and thermocline depth are calculated according to established literature definitions and returned to the user in a time series format. The program

Jordan S. Read; David P. Hamilton; Ian D. Jones; Kohji Muraoka; Luke A. Winslow; Ryan Kroiss; Chin H. Wu; Evelyn Gaiser

2011-01-01

397

Assessment of product stability  

Microsoft Academic Search

In this paper the mechanical stability of consumer products is discussed from both a theoretical and a practical point of view. It is shown that the two methods of stability testing most often used in product safety standards (inclined plane and destabilizing force) can be used for determining a third important parameter, the overturning energy. Furthermore, test results for a

Dirk van Aken; Ken J. Biswell; Trevor Evans

1994-01-01

398

Homological stabilizer codes  

SciTech Connect

In this paper we define homological stabilizer codes on qubits which encompass codes such as Kitaev's toric code and the topological color codes. These codes are defined solely by the graphs they reside on. This feature allows us to use properties of topological graph theory to determine the graphs which are suitable as homological stabilizer codes. We then show that all toric codes are equivalent to homological stabilizer codes on 4-valent graphs. We show that the topological color codes and toric codes correspond to two distinct classes of graphs. We define the notion of label set equivalencies and show that under a small set of constraints the only homological stabilizer codes without local logical operators are equivalent to Kitaev's toric code or to the topological color codes. - Highlights: Black-Right-Pointing-Pointer We show that Kitaev's toric codes are equivalent to homological stabilizer codes on 4-valent graphs. Black-Right-Pointing-Pointer We show that toric codes and color codes correspond to homological stabilizer codes on distinct graphs. Black-Right-Pointing-Pointer We find and classify all 2D homological stabilizer codes. Black-Right-Pointing-Pointer We find optimal codes among the homological stabilizer codes.

Anderson, Jonas T., E-mail: jonastyleranderson@gmail.com

2013-03-15

399

Frontogenetical Circulations and Stability  

NSDL National Science Digital Library

âFrontogenetical Circulations and Stabilityâ is a Webcast by Dr. James T. Moore that focuses on an overview of different stability types, including convective, potential, inertial, conditional and symmetric, the concept of frontogenesis and associated circulations. The webcast concludes with a discussion of the role of stability in determining the character of frontogenetical circulations.

Comet

2007-10-24

400

Stability of dynamical systems  

Microsoft Academic Search

A new definition of the stability of ordinary differential equations is proposed as an alternative to structural stability. It is particularly aimed at dissipative nonlinear systems, including those with chaos or strange attractors. The definition is as follows. Given a vector field nu on an oriented manifold X, and given epsilon <0, let u be the steady state of the

E. C. Zeeman

1988-01-01

401

Stabilized radio frequency quadrupole  

DOEpatents

A long-vane stabilized radio frequency resonator for accelerating charged particles and including means defining a radio frequency resonator cavity, a plurality of long vanes mounted in the defining means for dividing the cavity into sections, and means interconnecting opposing ones of the plurality of vanes for stabilizing the resonator.

Lancaster, Henry D. (Orinda, CA); Fugitt, Jock A. (Berkeley, CA); Howard, Donald R. (Danville, CA)

1984-01-01

402

The Stability of Submarines  

Microsoft Academic Search

SIR WILLIAM WHITE, in his paper in the Roy. Soc. Proceedings (vol. lxxvii. A., p. 528), discusses the hydrostatic forces tending to stability or instability of a submarine at the surface of the water. When the vessel is in motion, hydrodynamical forces come into play from the stream-line action of the water, and these also will affect the stability of

J. H. Jeans

1906-01-01

403

Head stabilization in herons  

Microsoft Academic Search

We examined head stabilization in relation to body mass and length of legs in four heron species (little egrets, Egretta garzetta; night herons, Nycticorax nycticorax; squacco herons, Ardeola ralloides; and cattle egrets, Bubulcus ibis: Aves: Ardeidae). Head stabilization, under controlled, sinusoidal, perch perturbations was mostly elicited at frequencies lower than 1 Hz. Maximal perturbation amplitudes sustained were positively correlated with

G. Katzir; E. Schechtman; N. Carmi; D. Weihs

2001-01-01

404

Rotorcraft aeroelastic stability  

NASA Technical Reports Server (NTRS)

Theoretical and experimental developments in the aeroelastic and aeromechanical stability of helicopters and tilt-rotor aircraft are addressed. Included are the underlying nonlinear structural mechanics of slender rotating beams, necessary for accurate modeling of elastic cantilever rotor blades, and the development of dynamic inflow, an unsteady aerodynamic theory for low-frequency aeroelastic stability applications. Analytical treatment of isolated rotor stability in hover and forward flight, coupled rotor-fuselage stability in hover and forward flight, and analysis of tilt-rotor dynamic stability are considered. Results of parametric investigations of system behavior are presented, and correlation between theoretical results and experimental data from small and large scale wind tunnel and flight testing are discussed.

Ormiston, Robert A.; Warmbrodt, William G.; Hodges, Dewey H.; Peters, David A.

1988-01-01

405

Process for stabilization of coal liquid fractions  

DOEpatents

Coal liquid fractions to be used as fuels are stabilized against gum formation and viscosity increases during storage, permitting the fuel to be burned as is, without further expensive treatments to remove gums or gum-forming materials. Stabilization is accomplished by addition of cyclohexanol or other simple inexpensive secondary and tertiary alcohols, secondary and tertiary amines, and ketones to such coal liquids at levels of 5-25% by weight with respect to the coal liquid being treated. Cyclohexanol is a particularly effective and cost-efficient stabilizer. Other stabilizers are isopropanol, diphenylmethanol, tertiary butanol, dipropylamine, triethylamine, diphenylamine, ethylmethylketone, cyclohexanone, methylphenylketone, and benzophenone. Experimental data indicate that stabilization is achieved by breaking hydrogen bonds between phenols in the coal liquid, thereby preventing or retarding oxidative coupling. In addition, it has been found that coal liquid fractions stabilized according to the invention can be mixed with petroleum-derived liquid fuels to produce mixtures in which gum deposition is prevented or reduced relative to similar mixtures not containing stabilizer.

Davies, Geoffrey (Boston, MA); El-Toukhy, Ahmed (Alexandria, EG)

1987-01-01

406

Stability of the pumpkin balloon  

NASA Astrophysics Data System (ADS)

A large axisymmetric balloon with positive differential pressure, e.g., a sphere, leads to high film stresses. These can be significantly reduced by using a lobed pumpkin-like shape re-enforced with tendons. A number of schemes have been proposed to achieve a cyclically symmetric pumpkin-shape at full inflation, including the constant bulge angle (CBA) design and the constant bulge radius (CBR) design. The authors and others have carried out stability studies of CBA and CBR designs and found instabilities under various conditions. While stability seems to be a good indicator of deployment problems for large balloons under normal ascent conditions, one cannot conclude that a stable design will deploy reliably. Nevertheless, stability analysis allows one to quantify certain deployment characteristics. Ongoing research by NASA's Balloon Program Office utilizes a new design approach developed by Rodger Farley, NASA/GSFC, that takes into account film and tendon strain. We refer to such a balloon as a constant stress (CS) pumpkin design. In June 2006, the Flight 555-NT balloon (based on a hybrid CBR/CBA design) developed an S-cleft and did not deploy. In order to understand the S-cleft phenomena and study a number of aspects related to the CS-design, a series of inflation tests were conducted at TCOM, Elizabeth City, NC in 2007. The test vehicles were 27 meter diameter pumpkins distinguished by their respective equatorial bulge angles (BA). For example, BA98 indicates an equatorial bulge angle of 98° . BA90, BA55, and BA00 are similarly defined. BA98 was essentially a one-third scale version of of the Flight 555 balloon (i.e., 12 micron film instead of 38.1 micron, mini-tendons, etc.). BA90 and BA55 were Farley CS-designs. BA00 was derived from the BA55 design so that a flat chord spanned adjacent tendons. In this paper, we will carry out stability studies of BA98, BA90, BA55, and BA00. We discuss the deployment problem of pumpkin balloons in light of 2007 inflation test results and flight data. In previous stability work, we added constant uniform perturbations to the design in our sensitivity studies. Here, we consider non-uniform perturbation as well. For example, a tendon may have a certain average slack strain s when measured over its entire length. However, there will be local variations ˆ about s. We explore such sensitivities via case studies. ˆ

Baginski, Frank

407

Edible Acid-Base Indicators.  

ERIC Educational Resources Information Center

Reports on the colors observed during titrations of 15 natural indicators obtained from common fruits and vegetables. These edible indicators can be used for a variety of teacher demonstrations or for simple student experiments. (JN)

Mebane, Robert C.; Rybolt, Thomas R.

1985-01-01

408

STEM Learning Quality Indicator Map  

E-print Network

STEM Learning Quality Indicator Map Quality Indicator Initiation Involvement Implementation Innovation Student Engagement STEM learning experiences are engaging and inspire creativity and imagination STEM learning experience is activity driven with specific step by step directions STEM learning

US Army Corps of Engineers

409

Thermal stability of naphthodiazoquinone sensitizers  

NASA Astrophysics Data System (ADS)

1,2-Napthoquinone diazides function as both photoactive dissolution inhibitors (PAC) for i-line positive resists and as photoacid generators (PAG) for chemically amplified resists. Traditionally, the 5-sulfonyl esters of 1,2- napthodiazoquinones (DQ) are used as PACS and recently the 4- sulfonyl (DQ) esters function as both PACS or PAGS. Knowledge of the thermal stability of the DQ is important for defining process conditions that stabilize the films prior to exposure or in post-treatments involving specific thermally induced reactions of PAC and resin. The thermal decomposition and photochemical decomposition of 1,2-napthodiazoquinones (DQ) follows similar pathways with the expulsion of nitrogen followed by formation of a reactive ketene. In absence of water (to form the indene carboxylic acid) many participatory bimolecular pathways involving reactant, products and resins are possible. Studies of the rate of decomposition of esters indicate that of 1-naptho-2-diazoquinone-4-sulfonyl derivatives are more thermally stable than the 5-sulfonyl counterparts and afford longer solution shelf life and higher thermal decomposition temperatures of 130 - 150 C. In addition, the 4-sulfonyl substituted DQ can form sulfonic acids upon thermolysis and hydrolysis. In solution, the napthodiazoquinones decompose at faster rates with lower activation energy (20 - 30 Kcal/mole) than in the solid state with higher activation energies of 40 - 50 Kcal/mole. When the DQ dissolution inhibitors are dispersed in resins, the interaction of the resin and DQ can influence the stability of the PAC. DQ mixed with novolak are more thermally stable than when blended with polyhydroxystyrene. The higher thermal stability of the 4-sulfonyl DQ esters is attributed to the electron resonance deactivation of diazo group by the sulfone subsituent.

Moreau, Wayne M.

1997-07-01

410

Susceptibility to trypsinolysis of esterified milk proteins.  

PubMed

Methyl-, ethyl- and propyl-esters of beta-lactoglobulin, alpha-lactalbumin and beta-casein were prepared and then hydrolyzed with trypsin in various conditions. Resulting hydrolysates were analysed by SDS electrophoresis and RP-HPLC. The degree of hydrolysis of esterified samples was generally lower than those of the non-modified proteins. The highest degrees of hydrolysis were obtained at pH 7--8 with native and esterified protein samples. beta-Lactoglobulin propyl ester and beta-casein methyl ester yielded the lowest degrees of hydrolysis. Ethyl- and propyl-esters of beta-casein showed high resistance towards tryptic attack, even after 20 h of hydrolysis. SDS electrophoretic patterns of tryptic hydrolysates of native proteins showed bands corresponding to low molecular weights. Tryptic hydrolysates of esterified proteins showed bands with higher sizes. RP-HPLC profiles of tryptic hydrolysates of esterified samples showed peaks with longer elution times than those obtained with native proteins, indicating the presence of more hydrophobic peptide populations. A peptic pre-treatment improved tryptic action on esterified proteins. It resulted in a better resolution of RP-HPLC profiles and in a complete disappearance of the protein after 20 h tryptic hydrolysis. PMID:11311716

Sitohy, M; Chobert, J M; Haertlé, T

2001-04-12

411

Indicators for Assessing Sustainability Performance  

Microsoft Academic Search

Sustainability is a universally advocated and quoted concept. To assess the sustainability performance of an entity, e.g,. a company, an industry or a country, appropriate indicators are often developed for the use of analysts and decision makers.\\u000a Numerous sustainability indicators can be found in the literature, which vary from a non-composite indicators to composite\\u000a indicators. We first deal with non-composite

P. Zhou; B. W. Ang

412

Life raft stabilizer  

NASA Technical Reports Server (NTRS)

An improved life raft stabilizer for reducing rocking and substantially precluding capsizing is discussed. The stabilizer may be removably attached to the raft and is defined by flexible side walls which extend a considerable depth downwardly to one another in the water. The side walls, in conjunction with the floor of the raft, form a ballast enclosure. A weight is placed in the bottom of the enclosure and water port means are provided in the walls. Placement of the stabilizer in the water allows the weighted bottom to sink, producing submerged deployment thereof and permitting water to enter the enclosure through the port means, thus forming a ballast for the raft.

Radnofsky, M. I.; Barnett, J. H., Jr.; Harrison, F. L.; Marak, R. J. (inventors)

1973-01-01

413

Stability of COBOL Clones  

E-print Network

Code clones are said to threaten the maintainability of software systems. Changes to one cloned fragment must be propagated to the other fragments, which might increase change effort. Hence, different studies have investigated the stability of cloned code and compared it to the stability of the non-cloned code. However, only open-source systems have been regarded so far. We conducted a study on two industrial COBOL systems, measuring the clone stability. In this paper, we present the results and compare them to the observations of the previous studies. 1

Jan Harder; Nils Göde; Marcus Rausch

414

Surface controlled blade stabilizer  

DOEpatents

Drill string stabilizer apparatus, controllable to expand and retract entirely from the surface by control of drill string pressure, wherein increase of drill string pressure from the surface closes a valve to create a piston means which is moved down by drill string pressure to expand the stabilizer blades, said valve being opened and the piston moving upward upon reduction of drill string pressure to retract the stabilizer blades. Upward and downward movements of the piston and an actuator sleeve therebelow are controlled by a barrel cam acting between the housing and the actuator sleeve.

Russell, Larry R. (6025 Edgemor, Suite C, Houston, TX 77081)

1983-01-01

415

Aerodynamically stabilized instrument platform  

NASA Technical Reports Server (NTRS)

A suspension apparatus for suspending instrumentation from an airborne platform may include a generally longitudinal boom having a payload end and a tail end. Yaw and pitch stabilizers may be disposed at the tail end of the boom. A mast that may be selectively translatable on the boom may connect the boom to a tether line of the airborne platform. The payload may be attached to the payload end of the boom. The mast may be positioned axially along the boom at the center of gravity of the combination of the payload, boom, pitch stabilizer, and yaw stabilizer.

Bland, Geoffrey L. (Inventor); Miles, Ted K. (Inventor)

2012-01-01

416

Plastic flow stability of nanotwinned Cu foils  

Microsoft Academic Search

The plastic flow stability of nanotwinned Cu foils was investigated via room temperature rolling. Nanotwinned Cu, with an average twin thickness of 5nm, exhibited stable plastic flow without shear localization or fracture, even at thickness reduction of over 50%. The retention of {111} fiber texture after rolling indicates insignificant out-of-plane rotation of the columnar grains and is interpreted in terms

O. Anderoglu; A. Misra; J. Wang; R. G. Hoagland; J. P. Hirth; X. Zhang

2010-01-01

417

Spacecraft stability and control  

NASA Technical Reports Server (NTRS)

The Earth's first artificial satellite, Sputnik 1, slowly tumbled in orbit. The first U.S. satellite, Explorer 1, also tumbled out of control. Today, satellite stability and control has become a higher priority. For a satellite design that is to have a life expectancy of 14 years, appropriate spacecraft flight control systems will be reviewed, stability requirements investigated, and an appropriate flight control system recommended in order to see the design process. Disturbance torques, including aerodynamic, magnetic, gravity gradient, solar, micrometeorite, debris, collision, and internal torques, will be assessed to quantify the disturbance environment so that the required compensating torques can be determined. The control torques, including passive versus active, momentum control, bias momentum, spin stabilization, dual spin, gravity gradient, magnetic, reaction wheels, control moment gyros, inertia augmentation techniques, three-axis control, and reaction control systems (RCSs), will be considered. Conditions for stability will also be considered.

Barret, Chris

1992-01-01

418

Homological Stabilizer Codes  

E-print Network

In this paper we define homological stabilizer codes which encompass codes such as Kitaev's toric code and the topological color codes. These codes are defined solely by the graphs they reside on. This feature allows us to use properties of topological graph theory to determine the graphs which are suitable as homological stabilizer codes. We then show that all toric codes are equivalent to homological stabilizer codes on 4-valent graphs. We show that the topological color codes and toric codes correspond to two distinct classes of graphs. We define the notion of label set equivalencies and show that under a small set of constraints the only homological stabilizer codes without local logical operators are equivalent to Kitaev's toric code or to the topological color codes.

Jonas T. Anderson

2011-07-18

419

Medial column stabilization.  

PubMed

This article presented a brief review of medial column stabilizing procedures. The various types of procedures that have been advocated for different deformities have been discussed. It is important to keep in mind that fusion of any of the medial column joints should not be performed as an isolated procedure in flexible flatfoot deformity. Medial column stabilization is only a component procedure when surgically managing a flexible flatfoot. When choosing procedures to correct a flexible flatfoot, thorough preoperative evaluation is important. It is also important to realize that conservative measures should be exhausted before attempting any type of stabilization of the medial column for flexible flatfoot deformity. Specific criteria for flexible flatfoot surgery should include severe uncontrollable deformity, an inability to wear standard foot gear, and persistent pain and disability despite exhaustive conservative therapy. A medial column stabilization is also an excellent procedure for those patients who have end-stage degenerative joint disease of the medial longitudinal arch. PMID:1893342

Catanzariti, A R

1991-07-01

420

Stochasticity and evolutionary stability  

NASA Astrophysics Data System (ADS)

In stochastic dynamical systems, different concepts of stability can be obtained in different limits. A particularly interesting example is evolutionary game theory, which is traditionally based on infinite populations, where strict Nash equilibria correspond to stable fixed points that are always evolutionarily stable. However, in finite populations stochastic effects can drive the system away from strict Nash equilibria, which gives rise to a new concept for evolutionary stability. The conventional and the new stability concepts may apparently contradict each other leading to conflicting predictions in large yet finite populations. We show that the two concepts can be derived from the frequency dependent Moran process in different limits. Our results help to determine the appropriate stability concept in large finite populations. The general validity of our findings is demonstrated showing that the same results are valid employing vastly different co-evolutionary processes.

Traulsen, Arne; Pacheco, Jorge M.; Imhof, Lorens A.

2006-08-01

421

Spacecraft stability and control  

NASA Astrophysics Data System (ADS)

The Earth's first artificial satellite, Sputnik 1, slowly tumbled in orbit. The first U.S. satellite, Explorer 1, also tumbled out of control. Today, satellite stability and control has become a higher priority. For a satellite design that is to have a life expectancy of 14 years, appropriate spacecraft flight control systems will be reviewed, stability requirements investigated, and an appropriate flight control system recommended in order to see the design process. Disturbance torques, including aerodynamic, magnetic, gravity gradient, solar, micrometeorite, debris, collision, and internal torques, will be assessed to quantify the disturbance environment so that the required compensating torques can be determined. The control torques, including passive versus active, momentum control, bias momentum, spin stabilization, dual spin, gravity gradient, magnetic, reaction wheels, control moment gyros, inertia augmentation techniques, three-axis control, and reaction control systems (RCSs), will be considered. Conditions for stability will also be considered.

Barret, Chris

422

Aluminum Waste Reaction Indicators in a Municipal Solid Waste Landfill  

E-print Network

(chemical); Waste disposal; Landfills. Author keywords: Solid waste; Leachate; Stability; LeachateAluminum Waste Reaction Indicators in a Municipal Solid Waste Landfill Timothy D. Stark, F.ASCE1 landfills may contain aluminum from residential and commercial solid waste, industrial waste, and aluminum

423

Biological Indicators of Watershed Health  

NSDL National Science Digital Library

This recently launched site on biological indicators, from the Environmental Protection Agency, is a gem, offering basic yet critical information on the what, where, why, and how of biological indicators. Presented in straightforward language, the site sets out to educate viewers about the importance of biological indicators -- those organisms that, because of their sensitivity to changes in the environment, "can provide accurate information about the health of a specific river, stream, lake, wetland, or estuary." The site is organized into seven main sections: Why use Indicators?, Key Concepts, Learn About State Programs, Biocriteria Resources, Fish as Indicators, Invertebrates as Indicators, and Periphyton as Indicators. In each section, a series of brief statements (with accompanying color photographs) leads the viewer through the logic, techniques, and methods used to assess watershed health. A collection of links rounds out the site.

424

Soil stabilization 1982  

NASA Astrophysics Data System (ADS)

Seven papers cover the following areas: design, construction and performance of lime, fly ash, and slag pavement; evaluation of heavily loaded cement stabilized bases; coal refuse and fly ash compositions; potential highway base course materials; lime soil mixture design considerations for soils of southeastern United States; short term active soil property changes caused by injection of lime and fly ash; soil cement for use in stream channel grade stabilization structures; and reaction products of lime treated southeastern soils.

Barenberg, E. J.; Thompson, M. R.; Tayabji, S. D.; Nussbaum, P. J.; Ciolko, A. T.

425

Shearing stability of lubricants  

NASA Technical Reports Server (NTRS)

Shearing stabilities of lubricating oils containing a high mol. wt. polymer as a viscosity index improver were studied by use of ultrasound. The oils were degraded by cavitation and the degradation generally followed first order kinetics with the rate of degradation increasing with the intensity of the ultrasonic irradiation and the cumulative energy applied. The shear stability was mainly affected by the mol. wt. of the polymer additive and could be determined in a short time by mechanical shearing with ultrasound.

Shiba, Y.; Gijyutsu, G.

1984-01-01

426

Temperature stabilized linkage  

NASA Technical Reports Server (NTRS)

A temperature compensated passive linkage for interconnecting two members having different coefficients of expansion. Preferably the linkage is utilized for interconnecting the stabilizer of a plane with its elevator. The stabilizer may be a graphite epoxy composite while the elevator may consist of aluminum-fiberglass. The differences in the rate of expansion of the two members is compensated by the linkage of the invention which in turn will move a side load hinge fitting to minimize aerodynamic and mechanical problems.

Ohgi, George Y. (Inventor)

1981-01-01

427

Photodegradation and photostability-indication of mequitazine  

NASA Astrophysics Data System (ADS)

The photochemical behavior is investigated for mequitazine (MQ) illustrating possible mechanisms and photodegradation products formed. Accelerated photolysis is done for MQ under justified stress conditions by subjecting aqueous drug solutions to radiation for specified period of time. Synthesis of the main photodegradants, the sulfoxide, is achieved. Selective quantification of MQ, singly in bulk form, pharmaceutical formulations and/or in the presence of its photodegradants is demonstrated. The indication of stability has been undertaken under conditions likely to be expected at normal storage conditions using a simple colorimetric method based on oxidation of the intact phenothiazine drug by potassium iodate in acid medium to form a red colored product adequate for quantitative estimation of the studied drug.

Abdel-Moety, Ezzat M.; Ibrahim, Mohamed A.; Rezk, Mamdouh R.

2009-10-01

428

Action indicators for injury prevention.  

PubMed

There is considerable confusion about the nature of indicators, their use in the injury field and surprisingly little discussion about these important tools. To date discussions of injury indicators have focused on the content and presentation of health outcome measures and on the dearth of data on exposure measures. Whereas these are valuable measures and assessing the optimal use of available routinely collected data in forming indicators is important, they do not provide sufficient information to support comprehensive prevention efforts, nor do they harness the full potential of indicators as tools to support prevention efforts. This paper provides an overview of the characteristics and uses of indicators for the field of injury prevention in order to make the case for action indicators and provide a framework for their appropriate use. PMID:20570988

MacKay, J Morag; Macpherson, Alison K; Pike, Ian; Vincenten, Joanne; McClure, Rod

2010-06-01

429

Controversially discussed indications for immunization  

Microsoft Academic Search

The indication for immunization in general or indications for selected vaccines are sometimes controversially discussed by\\u000a parents, the media and even by some parts of the medical community. This controversial discussion can cause confusion for\\u000a people who want to make decisions about immunization for their children or themselves. There is clearly a need for accurate\\u000a and evidence-based information about indications

Sieghart Dittmann

430

Electrodynamic stability of a self gravitating fluid cylinder  

Microsoft Academic Search

The electrogravitational stability of a dielectric fluid cylinder (density rho1) bounded by an infinite dielectric medium (density rho2) is investigated. The dispersion relation is derived and studied analytically and numerically. The analysis indicates that an applied axial electric field has a strong stabilizing influence as ?i > ?e (the dielectric constant). It is found that the model is gravitationally stable

Samia S. Elazab

1995-01-01

431

‘War don don’: stability, normalcy and Sierra Leone  

Microsoft Academic Search

There are few consistently reliable indicators of stability in post-conflict countries, but police behaviour is one of them. Based on the premise that stability has less to do with the introduction of specific institutions and procedures, and more to do with how people assess their environment and go about their routine business, this article uses police reform in Sierra Leone,

Alice Hills

2011-01-01

432

Observations on the leading edge in lifted flame stabilization  

Microsoft Academic Search

The objective of this paper is to report some of the first experimental evidence for the “leading edge” flame as the stabilization mechanism in lifted jet diffusion flames [1–5]. CH fluorescence has been used to indicate the flame front location (i.e., region of chemical reaction) and thereby characterize features of the stabilization region [5, 6]. The “leading edge” flame phenomenon

K. A. Watson; K. M. Lyons; J. M. Donbar; C. D. Carter

1999-01-01

433

Three-body orbital stability criteria for circular orbits  

Microsoft Academic Search

Previous investigations of the stability of hierarchical three-body systems by Harrington and by Black and his collaborators give conflicting results. A new numerical examination of such systems and the corresponding stability criteria indicate that the Black functions give the general qualitative behavior for very large and very small values of the third component; while for the range close to the

J. R. Donnison; D. F. Mikulskis

1992-01-01

434

Boiling water reactor stability analysis with RETRAN-03  

Microsoft Academic Search

An MOC option has been developed to eliminate the numerical diffusion associated with the time domain analysis of small perturbations. This model has been implemented as an option in RETRAN-03 and evaluated for BWR stability applications by comparing RETRAN analyses results with data from a series of stability tests from the Vermont Yankee reactor. The results indicate that the MOC

P. A. Bergeron; N. Fujita; M. P. Paulsen; J. H. McFadden; L. J. Agee

1994-01-01

435

The Reliability and Classification Stability of the Learning Style Inventory  

Microsoft Academic Search

The Learning Style Inventory (LSI) and the newly revised Learning Style Inventory (LSI II) were examined for internal consistency, test-retest reliability and stability of the four classifications resulting from their scores. Internal consistency was much improved in the LSI II, but problems with low test-retest indices and classification stability continue to plague the instruments. The authors hypothesize that the observed

Ronald R. Sims; John G. Veres; Patricia Watson; Kathryn E. Buckner

1986-01-01

436

Stability study of losartan/hydrochlorothiazide tablets.  

PubMed

The purpose of stability testing is to investigate how the quality of a drug product changes with time under the influence of environmental factors, to establish a shelf life for the product and to recommend storage conditions. Stability study of losartan/hydrochlorothiazide tablets is presented in this paper. Losartan (angiotensin II receptor antagonist) and hydrochlorothiazide (diuretic) are successfully used in association in the treatment of hypertension. Stability study of losartan/hydrochlorothiazide tablets consisted of three steps: stress test (forced degradation study), preliminary testing (selection of packaging) and formal stability testing. The results of stress test suggested that losartan/hydrochlorothiazide tablets are sensitive to moisture. It was demonstrated that the developed analytical methods are stability indicating. Additional preliminary testing was performed in order to select appropriate packaging for losartan/hydrochlorothiazide tablets. OPA/Al/PVC//Al blisters were found to provide adequate protection for the product. Based on the first 12 months of the formal stability study, a shelf life of 24 months was proposed. Losartan/hydrochlorothiazide tablets in OPA/Al/PVC//Al blisters are demonstrated to be chemically, physically and microbiologically stable. PMID:15707739

Lusina, Maja; Cindri?, Tanja; Tomai?, Jadranka; Peko, Marijana; Pozai?, Lidija; Musulin, Nenad

2005-03-01

437

Aquifer stability investigations  

SciTech Connect

The study of compressed air energy storage (CAES) in porous rock reservoirs is carried out within the Reservoir Stability Studies Program at Pacific Northwest Laboratory. The goal of the study is to establish criteria for long-term stability of aquifer CAES reservoirs. These criteria are intended to be guidelines and check lists that utilities and architect-engineering firms may use to evaluate reservoir stability at candidate CAES sites. These criteria will be quantitative where possible, qualitative where necessary, and will provide a focal point for CAES relevant geotechnical knowledge, whether developed within this study or available from petroleum, mining or other geotechnical practices using rock materials. The Reservoir Stability Studies Program had four major activities: a state-of-the-art survey to establish preliminary stability criteria and identify areas requiring research and development; numerical modeling; laboratory testing to provide data for use in numerical models and to investigate fundamental rock mechanics, thermal, fluid, and geochemical response of aquifer materials; and field studies to verify the feasibility of air injection and recovery under CAES conditions in an aquifer, to validate and refine the stability criteria, and to evaluate the accuracy and adequacy of the numerical and experimental methodologies developed in previous work. Three phases of study, including preliminary criteria formulation, numerical model development, and experimental assessment of CAES reservoir materials have been completed. Present activity consists of construction and operation of the aquifer field test, and associated numerical and experimental work in support of that activity. Work is presently planned to be complete by 1983 at the end of the field test. At that time the final stability criteria for aquifers will be issued. Attached here also are preliminary criteria for aquifers.

Allen, R.D.; Doherty, T.J.

1981-09-01

438

Leading Indicators of Currency Crises  

Microsoft Academic Search

This paper examines the empirical evidence on currency crises and proposes a specific early warning system. This system involves monitoring the evolution of several indicators that tend to exhibit an unusual behavior in the periods preceding a crisis. When an indicator exceeds a certain threshold value, this is interpreted as a warning \\

Graciela Kaminsky; Carmen M. Reinhart

1998-01-01

439

Lexical-Grammatical Pragmatic Indicators.  

ERIC Educational Resources Information Center

A study of the interlanguage pragmatics of learners of Hebrew and English (L2s) focuses on pragmatic indicators used in requests and apologies (situations in Appendix). Deviations from native-speaker norms in the speech of non-native speakers are discussed. Results suggest L2s' misuse of pragmatic indicators can have serious interactional…

Blum-Kulka, Shoshana; Levenston, Edward A.

1987-01-01

440

Calibration of rod position indicators  

Microsoft Academic Search

This patent describes a procedure for calibration of a rod position indicator in a nuclear reactor having movable control rods without total shutdown of the reactor. It comprises: noting that the indicated position of a rod differs from a demand position of the rod by an extent exceeding a predetermined error range, determining that the rod is actually within the

A. P. Ginsberg; J. P. Mooney

1991-01-01