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Sample records for stability indicating rp-hplc

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

    PubMed Central

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

    2014-01-01

    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 μm 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

  2. A Stability-Indicating RP-HPLC Assay Method for 5-Fluorouracil

    PubMed Central

    Sinha, V. R.; Kumar, R. V.; Bhinge, J. R.

    2009-01-01

    The present study describes the development of a validated RP-HPLC method for the determination of 5-fluorouracil in presence of its degradation products or other pharmaceutical excipients. Stress studies were performed on 5-fluorouracil and it was found that it degrades sufficiently in alkaline conditions, while negligible degradation was observed in acidic, neutral, oxidative and photolytic conditions. The peaks of the degradation products were not observed in the chromatogram due to the nonchromophoric nature of the degradation moiety formed. The separations were carried out on a C-18 reversed phase column (Phenomenex; Prodigy ODS3V, 250×4.6 mm, 5 μ) using 50mM KH2PO4 (pH, 5.0) as mobile phase at a flow rate of 1.2 ml/min and temperature of 30°. The wavelength of detection was 254 nm. A retention time of nearly 6 minutes was obtained. Analytical validation parameters such as specificity and selectivity, linearity, accuracy and precision were evaluated. The calibration curve for 5-fluorouracil was linear (r2=0.999±0.0005) from range of 10 μg/ml to 100 μg/ml. Relative standard deviation values for all the key parameters, was less than 2.0 %. The recovery of the drug after standard addition to the degraded sample was found to be 104.69%. Thus, the developed RP-HPLC method was found to be suitable for the determination of 5-fluorouracil in bulk as well as stability samples of the pharmaceutical dosage forms containing various excipients. PMID:20376215

  3. Stability indicating RP-HPLC method for simultaneous determination of piroxicam and ofloxacin in binary combination.

    PubMed

    John, Peter; Azeem, Waqar; Ashfaq, Muhammad; Khan, Islam Ullah; Razzaq, Syed Naeem

    2015-09-01

    A simple and precise RP-HPLC method was developed for simultaneous determination of piroxicam and ofloxacin in pharmaceutical formulations and human serum. Optimum separations of piroxicam, ofloxacin and stress-induced degradation products were achieved by use of Hypersil BDS C8 column (250 x 4.6mm, 5 μm). The mobile phase was a mixture of acetonitrile: 0.012M K2HPO4: 0.008M sodium citrate (both buffers mixed and pH adjusted to 2.8) (50:25:25 v/v/v) delivered at flow rate of 1.5 mL min⁻¹ using DAD at 254 nm. Response was linear function of concentration over the ranges of 70-130 mg mL⁻¹ for piroxicam and ofloxacin (r² ≥ 0.999). The method efficiently separated the analytical peaks from degradation products with acceptable tailing and resolution. The developed method was successfully used for concurrent analysis of piroxicam and ofloxacin in pharmaceutical formulations, human serum and in vitro drug interaction studies. PMID:26408892

  4. A validated specific stability-indicating RP-HPLC assay method for the determination of loteprednol etabonate in eye drops.

    PubMed

    Han, Yong K; Segall, Adriana I

    2015-01-01

    A new stability-indicating RP-HPLC assay method was developed and validated for quantitative determination of loteprednol etabonate in bulk drugs and in ophthalmic suspensions in the presence of degradation products generated from forced degradation studies. The system consisted of Agilent Technologies Zorbax Eclipse XDB-Phenyl 5 µm 4.6 × 250 mm, and detection was performed at 244 nm. The mobile phase consisted of water-acetonitrile-acetic acid (34.5:65.0:0.5, v/v/v) run at a flow rate of 1 mL/min and maintained at room temperature. The calibration curve was linear from 30 to 70 µg/mL with r > 0.999. Accuracy (mean recovery 100.78%) and precision were found to be satisfactory. Stress conditions including acid and alkali hydrolysis, water stress, oxidation, photolysis and heat were applied. The degradation products did not interfere with the detection of loteprednol etabonate, thus the method can be considered as a stability-indicating method. The proposed method can be used for quality control assay of loteprednol etabonate in bulk drug and in ophthalmic suspensions and for stability studies as a result of the ability of the method to separate loteprednol etabonate from its degradation products and excipients. PMID:25234383

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

    PubMed Central

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

    2013-01-01

    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 μm 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 μg/ml and 0.38 μg/ml for doxofylline, 2.08 μg/ml and 0.62 μg/ml for terbutaline sulphate, respectively. PMID:24482767

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

    PubMed

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

    2013-12-01

    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 μm 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 μg/ml and 0.38 μg/ml for doxofylline, 2.08 μg/ml and 0.62 μg/ml for terbutaline sulphate, respectively. PMID:24482767

  7. Stability-Indicating RP-HPLC Method for Simultaneous Estimation of Enrofloxacin and Its Degradation Products in Tablet Dosage Forms.

    PubMed

    Chakravarthy, V Ashok; Sailaja, B B V; Kumar, Avvaru Praveen

    2015-01-01

    The present work was the development of a simple, efficient, and reproducible stability-indicating reverse-phase high performance liquid chromatographic (RP-HPLC) method for simultaneous determination enrofloxacin (EFX) and its degradation products including ethylenediamine impurity, desfluoro impurity, ciprofloxacin impurity, chloro impurity, fluoroquinolonic acid impurity, and decarboxylated impurity in tablet dosage forms. The separation of EFX and its degradation products in tablets was carried out on Kromasil C-18 (250 × 4.6 mm, 5 μm) column using 0.1% (v/v) TEA in 10 mM KH2PO4 (pH 2.5) buffer and methanol by linear gradient program. Flow rate was 1.0 mL min(-1) with a column temperature of 35°C and detection wavelength was carried out at 278 nm and 254 nm. The forced degradation studies were performed on EFX tablets under acidic, basic, oxidation, thermal, humidity, and photolytic conditions. The degraded products were well resolved from the main active drug and also from known impurities within 65 minutes. The method was validated in terms of specificity, linearity, LOD, LOQ, accuracy, precision, and robustness as per ICH guidelines. The results obtained from the validation experiments prove that the developed method is a stability-indicating method and suitable for routine analysis. PMID:25705547

  8. Development and Validation of Stability Indicating RP-HPLC Method for Voriconazole.

    PubMed

    Khetre, A B; Sinha, P K; Damle, Mrinalini C; Mehendre, R

    2009-09-01

    This study describes the development and validation of stability indicating HPLC method for voriconazole, an antifungal drug. Voriconazole was subjected to stress degradation under different conditions recommended by International Conference on Harmonization. The sample so generated was used to develop a stability-indicating high performance liquid chromatographic method for voriconazole. The peak for voriconazole was well resolved from peaks of degradation products, using a Hypersil C18 (250x4.6 mm) column and a mobile phase comprising of acetonitrile: water (40:60, v/v), at flow rate of 1 ml/min. Detection was carried out using photodiode array detector. A linear response (r > 0.99) was observed in the range of 5-25 mug/ml. The method showed good recoveries (average 100.06%) and relative standard deviation for intra and inter-day were

  9. Development and Validation of a Stability-Indicating Assay of Etofenamate by RP-HPLC and Characterization of Degradation Products.

    PubMed

    Peraman, Ramalingam; Nayakanti, Devanna; Dugga, Hari Hara Theja; Kodikonda, Sudhakara

    2013-12-01

    A validated stability-indicating RP-HPLC method for etofenamate (ETF) was developed by separating its degradation products on a C18 (250 mm × 4.6 mm 5 μm) Qualisil BDS column using a phosphate buffer (pH-adjusted to 6.0 with orthophosphoric acid) and methanol in the ratio of 20:80 % v/v as the mobile phase at a flow rate of 1.0 mL/min. The column effluents were monitored by a photodiode array detector set at 286 nm. The method was validated in terms of specificity, linearity, accuracy, precision, detection limit, quantification limit, and robustness. Forced degradation of etofenamate was carried out under acidic, basic, thermal, photo, and peroxide conditions and the major degradation products of acidic and basic degradation were isolated and characterized by (1)H-NMR, (13)C-NMR, and mass spectral studies. The mass balance of the method varied between 92-99%. PMID:24482770

  10. Development and Validation of a Stability-Indicating Assay of Etofenamate by RP-HPLC and Characterization of Degradation Products

    PubMed Central

    Peraman, Ramalingam; Nayakanti, Devanna; Dugga, Hari Hara Theja; Kodikonda, Sudhakara

    2013-01-01

    A validated stability-indicating RP-HPLC method for etofenamate (ETF) was developed by separating its degradation products on a C18 (250 mm × 4.6 mm 5 μm) Qualisil BDS column using a phosphate buffer (pH-adjusted to 6.0 with orthophosphoric acid) and methanol in the ratio of 20:80 % v/v as the mobile phase at a flow rate of 1.0 mL/min. The column effluents were monitored by a photodiode array detector set at 286 nm. The method was validated in terms of specificity, linearity, accuracy, precision, detection limit, quantification limit, and robustness. Forced degradation of etofenamate was carried out under acidic, basic, thermal, photo, and peroxide conditions and the major degradation products of acidic and basic degradation were isolated and characterized by 1H-NMR, 13C-NMR, and mass spectral studies. The mass balance of the method varied between 92–99%. PMID:24482770

  11. Stability-Indicating RP-HPLC Method for the Determination of Ambrisentan and Tadalafil in Pharmaceutical Dosage Form

    PubMed Central

    Patel, Jayvadan K.; Patel, Nilam K.

    2014-01-01

    Abstract A simple, rapid, and highly selective RP-HPLC method was developed for the simultaneous determination of Ambrisentan (AMB) and Tadalafil (TADA) drug substances in the fixed dosage strength of 10 mg and 40 mg, respectively. Effective chromatographic separation was achieved using a Hypersil GOLD C18 column (150 mm × 4.6 mm internal diameter, 5 μm particle size) with a mobile phase composed of methanol, water, and acetonitrile in the ratio of 40:40:20 (by volume). The mobile phase was pumped using a gradient HPLC system at a flow rate of 0.5 mL/min, and quantification of the analytes was based on measuring their peak areas at 260 nm. The retention times for Ambrisentan and Tadalafil were about 2.80 and 7.10 min, respectively. The reliability and analytical performance of the proposed HPLC procedure were statistically validated with respect to system suitability, linearity, ranges, precision, accuracy, specificity, robustness, detection, and quantification limits. Calibration curves were linear in the ranges of 1–20 μg/mL for Ambrisentan and 4–80 μg/mL for Tadalafil with correlation coefficients >0.990. The proposed method proved to be selective and stability-indicating by the resolution of the two analytes from the forced degradation (hydrolysis, oxidation, and photolysis) products. The validated HPLC method was successfully applied to the analysis of AMB and TADA in pharmaceutical dosage form. PMID:26279975

  12. New Stability-Indicating RP-HPLC Method for Determination of Diclofenac Potassium and Metaxalone from their Combined Dosage Form

    PubMed Central

    Panda, Sagar Suman; Patanaik, Debasis; Ravi Kumar, Bera V. V.

    2012-01-01

    A simple, precise and accurate isocratic RP-HPLC stability-indicating assay method has been developed to determine diclofenac potassium and metaxalone in their combined dosage forms. Isocratic separation was achieved on a Hibar-C18, Lichrosphere-100® (250 mm × 4.6 mm i.d., particle size 5 μm) column at room temperature in isocratic mode, the mobile phase consists of methanol: water (80:20, v/v) at a flow rate of 1.0 ml/min, the injection volume was 20 μl and UV detection was carried out at 280nm. The drug was subjected to acid and alkali hydrolysis, oxidation, photolysis and heat as stress conditions. The method was validated for specificity, linearity, precision, accuracy, robustness and system suitability. The method was linear in the drug concentration range of 2.5–30 μg/ml and 20–240 μg/ml for diclofenac potassium and metaxalone, respectively. The precision (RSD) of six samples was 0.83 and 0.93% for repeatability, and the intermediate precision (RSD) among six-sample preparation was 1.63 and 0.49% for diclofenac potassium and metaxalone, respectively. The mean recoveries were between 100.99–102.58% and 99.97–100.01% for diclofenac potassium and metaxalone, respectively. The proposed method can be used successfully for routine analysis of the drug in bulk and combined pharmaceutical dosage forms. PMID:22396909

  13. Stability-Indicating RP-HPLC Method for Estimation of Miglitol in Bulk and Tablets

    PubMed Central

    Shrivastava, B.; Baghel, U. S.; Sahu, M.

    2010-01-01

    A selective and sensitive, stability-indicating reverse phase high performance liquid chromatography method has been first developed and validated for the estimation of miglitol in bulk and tablet dosages form. Samples were separated on a prepacked, Inertsil amino C18 column (150×4.6 mm i.d.) using a mobile phase comprised of acetonitrile and monobasic sodium phosphate pH 7.5 (80:20, v/v) delivered at 1.5 ml/min flow rate. Detection was performed on a SPD-20A prominence UV/Vis detector at 220 nm. The retention time for miglitol was 13.93±0.0367. The method was validated in terms of linearity, precision, accuracy, ruggedness, and specificity, limit of detection and limit of quantification. The linearity (r2) and percentage recoveries of miglitol were 0.9986 and 99.85%. This method is suitable for routine estimation of miglitol in bulk and tablet dosages form. PMID:21969753

  14. 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

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

    2013-06-01

    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 μm (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

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

    PubMed

    Trivedi, Harshal Kanubhai; Patel, Mukesh C

    2012-12-01

    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 μm) 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

  16. Development and Validation of a Stability-Indicating RP-HPLC Method for the Assay of Pristinamycin in Bulk and Tablet Dosage Form.

    PubMed

    Mallikarjuna Rao, Nagasarapu; Gowrisankar, Dannana

    2016-01-01

    Pristinamycin is an antibiotic used mainly in the treatment of Staphylococcus infections. The aim of this study was to develop a rapid and simple stability-indicating RP-HPLC method for the determination of pristinamycin in tablet dosage form. Pristinamycin was eluted on the ACE-5, C18-HL, 250 x 4.6 mm, 5 µm analytical column with a mobile phase consisting of 0.2% orthophosphoric acid and acetonitrile 63:37 v/v, pumped at 1.5 ml/min flow rate. The column was maintained at 40°C and 10 μl of the solutions were injected. UV detection was performed at 206 nm. The procedure separated pristinamycin and its potential degradation products in an overall analysis time of less than 10 min with pristinamycin eluting at about 3 min. The method was validated according to the regulatory guidelines with respect to specificity, precision, accuracy, linearity, and robustness. Forced degradation studies were also performed for pristinamycin bulk drug samples to demonstrate the stability-indicating power of the HPLC method. The % RSD of system precision and method precision was found to be 0.64 and 1.49%, respectively. The procedure provided a linear response over the concentration range 25-150 μg/ml (r = 0.9998). Finally, the applicability of the method was evaluated in the tablet dosage form as well as in stability samples. PMID:27222604

  17. Development and Validation of a Stability-Indicating RP-HPLC Method for the Assay of Pristinamycin in Bulk and Tablet Dosage Form

    PubMed Central

    Mallikarjuna Rao, Nagasarapu; Gowrisankar, Dannana

    2016-01-01

    Pristinamycin is an antibiotic used mainly in the treatment of Staphylococcus infections. The aim of this study was to develop a rapid and simple stability-indicating RP-HPLC method for the determination of pristinamycin in tablet dosage form. Pristinamycin was eluted on the ACE-5, C18-HL, 250 x 4.6 mm, 5 µm analytical column with a mobile phase consisting of 0.2% orthophosphoric acid and acetonitrile 63:37 v/v, pumped at 1.5 ml/min flow rate. The column was maintained at 40°C and 10 μl of the solutions were injected. UV detection was performed at 206 nm. The procedure separated pristinamycin and its potential degradation products in an overall analysis time of less than 10 min with pristinamycin eluting at about 3 min. The method was validated according to the regulatory guidelines with respect to specificity, precision, accuracy, linearity, and robustness. Forced degradation studies were also performed for pristinamycin bulk drug samples to demonstrate the stability-indicating power of the HPLC method. The % RSD of system precision and method precision was found to be 0.64 and 1.49%, respectively. The procedure provided a linear response over the concentration range 25–150 μg/ml (r = 0.9998). Finally, the applicability of the method was evaluated in the tablet dosage form as well as in stability samples.

  18. Development and Validation of a Stability-Indicating RP-HPLC Method by a Statistical Optimization Process for the Quantification of Asenapine Maleate in Lipidic Nanoformulations.

    PubMed

    Managuli, Renuka S; Kumar, Lalit; Chonkar, Ankita D; Shirodkar, Rupesh K; Lewis, Shaila; Koteshwara, Kunnatur B; Reddy, Meka Sreenivasa; Mutalik, Srinivas

    2016-09-01

    A stability-indicating RP-HPLC method was developed for quantification of asenapine maleate (ASPM) in lipid nanoformulations. The proposed method was used to assess intrinsic stability of ASPM by conducting force degradation study. The results indicated no considerable degradation of ASPM on subjecting it to hydrolytic, oxidative, thermal and photolytic stresses. The method was validated according to ICH Q2(R1) guidelines by employing Full factorial design using Design-Expert(®) software. ASPM was precisely and accurately quantified in nanoparticles by separating it on Hyperclone BDS C18 using 80-20% v/v mixture of potassium phosphate solution containing 0.1% v/v triethylamine and acetonitrile. The effect of flow rate, pH, acetonitrile content and column temperature was assessed on method responses. The current method was linear in the range of 0.1-20 µg/mL with limit of detection (LOD) and limit of quantification (LOQ) of 29 and 89 ng/mL, respectively. The method was precise and accurate in the determination of ASPM with peak area RSD and recovery of <1.0% and 97-101% in bulk drug solution and of <1.0% and 92-104% in nanoformulations, respectively. Analysis of variance indicated the significance (P < 0.0001) of a statistical model in validating the method with respect to change in independent chromatographic factors. The developed method was successfully employed in determining ASPM content in bulk and lipid nanoformulations. PMID:27130879

  19. Novel Stability-Indicating RP-HPLC Method for the Simultaneous Estimation of Clindamycin Phosphate and Adapalene along with Preservatives in Topical Gel Formulations.

    PubMed

    Modi, Prakash B; Shah, Nehal J

    2014-12-01

    A novel stability-indicating RP-HPLC method was developed for the simultaneous estimation of clindamycin phosphate (hydrophilic), adapalene (hydro-phobic), phenoxyethanol, and methylparaben in topical gel formulations. Optimum chromatographic separation among the analytes and stress-induced degradants peaks was achieved on the XBridge C18 (50 × 4.6 mm, 3.5 µm) column using a mobile phase consisting of a variable mixture of pH 2.50 ammonium hydrogen phosphate buffer, acetonitrile, and tetrahydrofuran with gradient elution. Detection was performed at 210 nm for phenoxyethanol, methylparaben, and clindamycin phosphate and 321 nm for adapalene. The method was optimized with a unique diluent selection for the extraction of clindamycin phosphate and adapalene from the gel matrix. The developed method was validated for method precision, specificity, LOD and LOQ, linearity, accuracy, robustness, and solution stability as per ICH guidelines. The proposed method can be employed for the quantification of clindamycin phosphate, adapalene, phenoxyethanol, and methylparaben in commercial topical gel formulations. PMID:26171325

  20. Novel Stability-Indicating RP-HPLC Method for the Simultaneous Estimation of Clindamycin Phosphate and Adapalene along with Preservatives in Topical Gel Formulations

    PubMed Central

    Modi, Prakash B.; Shah, Nehal J.

    2014-01-01

    Abstract A novel stability-indicating RP-HPLC method was developed for the simultaneous estimation of clindamycin phosphate (hydrophilic), adapalene (hydro-phobic), phenoxyethanol, and methylparaben in topical gel formulations. Optimum chromatographic separation among the analytes and stress-induced degradants peaks was achieved on the XBridge C18 (50 × 4.6 mm, 3.5 µm) column using a mobile phase consisting of a variable mixture of pH 2.50 ammonium hydrogen phosphate buffer, acetonitrile, and tetrahydrofuran with gradient elution. Detection was performed at 210 nm for phenoxyethanol, methylparaben, and clindamycin phosphate and 321 nm for adapalene. The method was optimized with a unique diluent selection for the extraction of clindamycin phosphate and adapalene from the gel matrix. The developed method was validated for method precision, specificity, LOD and LOQ, linearity, accuracy, robustness, and solution stability as per ICH guidelines. The proposed method can be employed for the quantification of clindamycin phosphate, adapalene, phenoxyethanol, and methylparaben in commercial topical gel formulations. PMID:26171325

  1. A validated specific stability-indicating RP-HPLC assay method for Ambrisentan and its related substances.

    PubMed

    Narayana, M B V; Chandrasekhar, K B; Rao, B M

    2014-09-01

    A validated specific stability-indicating reverse-phase liquid chromatographic method was developed for the quantitative determination of Ambrisentan as well as its related substances in bulk samples, pharmaceutical dosage forms in the presence of degradation products and its related impurities. Forced degradation studies were performed on bulk samples of Ambrisentan as per the ICH-prescribed stress conditions using acid, base, oxidative, thermal stress and photolytic degradation to show the stability-indicating power of the LC method. Significant degradation in acidic, basic stress conditions was observed and no degradation was observed in other stress conditions. The chromatographic method was optimized using the samples generated from the forced degradation studies and the impurity-spiked solution. Good resolution between the peaks corresponds to Ambrisentan-related impurities and degradation products from the analyte were achieved on a SunFire C18 column using a mobile phase consisting of a mixture of potassium dihydrogen orthophosphate at a pH adjusted to 2.5 with ortho-phosphoric acid in water and a mixture of acetonitrile:methanol using a simple linear gradient. The detection was carried out at 225 nm. The limit of detection and the limit of quantification for the Ambrisentan and its related impurities were established. The stressed test solutions were assayed against the qualified working standard of Ambrisentan and the mass balance in each case was between 98.9 and 100.3%, indicating that the developed LC method was stability indicating. Validation of the developed LC method was carried out as per the ICH requirements. The developed method was found to be suitable to check the quality of bulk samples of Ambrisentan at the time of batch release and also during its storage (long-term and accelerated stability). PMID:23926121

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

    PubMed Central

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

    2014-01-01

    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 μ). 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 μg/ml and 8-60 μg/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. PMID:25425754

  3. Development of validated stability indicating assay method for simultaneous estimation of metformin hydrochloride and vildagliptin by RP-HPLC.

    PubMed

    Satheeshkumar, N; Pradeepkumar, M; Shanthikumar, S; Rao, V J

    2014-03-01

    A simple, precise and stability-indicating HPLC method was developed and validated for the simultaneous determination of metformin hydrochloride (MET) and vildagliptin (VLG) in pharmaceutical dosage forms. The method involves use of easily available inexpensive laboratory reagents. The separation was achieved on Grace Cyano column (250 mm×4.6 mm) 5 µm with isocratic flow. The mobile phase was pumped at a flow rate of 1.0 mL/min, consisted of 25 mM ammonium bicarbonate buffer and acetonitrile (65:35, v/v). The UV detection was carried out at 207 nm. A linear response was observed over the concentration range of 25-125 µg/mL for MET and 50-250 µg/mL for VLG respectively. Limit of detection and limit of quantification for MET were 0.36 µg/mL and 1.22 µg/mL, and for VLG were 0.75 µg/mL and 2.51 µg/mL respectively. The method was successfully validated in accordance to ICH guidelines acceptance criteria for specificity, linearity, accuracy, precision, robustness, and system suitability. Individual drugs (MET and VLG) were exposed to thermal, photolytic, hydrolytic and oxidative stress conditions. The resultant stressed samples were analyzed by the proposed method. The method gave high resolution among the degradation products and the analytes. The peak purity of analyte peak in the stressed samples was confirmed by photo diode array detector. The proposed method was successfully applied for the quantitative analysis of MET and VLG in tablet dosage form, which will help to improve quality control and contribute to stability studies of pharmaceutical tablets containing these drugs. PMID:24081820

  4. A stability-indicating RP-HPLC method for the quantitative analysis of meclizine hydrochloride in tablet dosage form.

    PubMed

    Peraman, Ramalingam; Manikala, Maheswari; Kondreddy, Vinod Kumar; Yiragamreddy, Padmanabha Reddy

    2015-01-01

    A specific stability-indicating reversed-phase high-performance liquid chromatographic method was developed and validated for the estimation of meclizine hydrochloride (MEC) in tablet dosage form. The HPLC method has shown adequate separation of MEC from their degradation products. The separation was achieved on a C8 (250 mm×4.6 mm×5 µm) column using a mobile phase composition of 0.2% triethylamine in water and methanol in the ratio of 65:35(pH adjusted to 3.0 with orthophosphoric acid) with a flow rate of 1 mL/min. The wavelength of a photo-diode array detector was kept at 229 nm. Stress studies were performed initially under milder conditions followed by stronger conditions so as to get sufficient degradation around 5-20%. There were six degradation products observed with adequate separation from the analyte peak. Among those detected degradation products, structures of four degradation products were verified by comparison with known impurities of meclizine analogs. The method was validated as per the International Conference on Harmonization (Q2) guidelines. The method was specific, selective, accurate and precise to quantify meclizine in the presence of degradation products. PMID:25644814

  5. Development and validation of a stability indicating RP-HPLC method for the simultaneous determination of related substances of albuterol sulfate and ipratropium bromide in nasal solution.

    PubMed

    Kasawar, Gajanan B; Farooqui, Mazahar

    2010-05-01

    A simple, sensitive and specific RP-HPLC method was developed for the quantification of related impurities of albuterol sulfate (AS) and ipratropium bromide (IB) in liquid pharmaceutical dosage form. The chromatographic separation employs gradient elution using an inertsil C8-3, 250mmx4.6mm, 5mum columns. Mobile phase consisting of solvent A (solution containing 2.5g of potassium dihydrogen phosphate and 2.87g of heptane-1-sulfonic acid sodium salt per liter of water, adjusted to pH 4 with orthophosphoric acid) and solvent B (acetonitrile) delivered at a flow rate of 1.0mlmin(-1). The analytes were detected and quantified at 210nm using photodiode array (PDA) detector. The method was validated as per ICH guidelines, demonstrating to be accurate and precise (repeatability and intermediate precision level) within the corresponding linear range of known impurities of AS and IB. The specificity of the method was investigated under different stress conditions including hydrolytic, oxidative, photolytic and thermal as recommended by ICH guidelines. Relevant degradation was found to take place under hydrolytic and oxidative conditions. Robustness against small modification in pH, column oven temperature, flow rate and percentage of the mobile phase composition was ascertained. Lower limit of quantification and detection were also determined. The peak purity indices (purity anglestability indicating capability of the method. PMID:20045275

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

    PubMed Central

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

    2014-01-01

    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 μm 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 μg/mL, 0.231–9.995 μg/mL, 0.230–10.089 μg/mL, 0.334–10.011 μg/mL, and 0.324–10.050 μg/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

  7. Development and validation of a stability indicating RP-HPLC method for simultaneous estimation of Olmesartan Medoxomil and Metoprolol Succinate in pharmaceutical dosage form

    PubMed Central

    Thakker, Nirmal M.; Panchal, Haresh B.; Rakholiya, Dinesh R.; Murugan, R.; Choudhari, Vishnu P.; Kuchekar, Bhanudas S.

    2012-01-01

    Aim and Backrgound: A simple, rapid, precise and isocratic RP-HPLC (Reverse Phase High Performance Liquid Chromatography) method is aimed to develop for the simultaneous estimation of Olmesartan Medoxomil and Metoprolol Succinate in bulk drug and pharmaceutical dosage form. Materials and Methods: The quantification is carried out using YMC-Pack CN (250 × 4.6 mm, 5.0 μm) column and the mobile phase comprises of 0.05% Trifluoro acetic acid (TFA) and Acetonitrile (ACN) (70:30 v/v). The flow rate is 1.0 ml/min. The eluent is monitored at 220 nm. The retention times of Olmesartan Medoxomil and Metoprolol Succinate are 7.9 min and 4.1 min respectively. The method is validated in terms of linearity, precision, accuracy, specificity, limit of detection and limit of quantitation. Results: Linearity and percentage recoveries of both Olmesartan Medoxomil and Metoprolol Succinate are in the range of 5-35 μg/ml and 100 ± 2%, respectively. The stress testing of both the drugs individually and their mixture is carried out under acidic, alkaline, oxidation, photo-stability and thermal degradation (dry heat and wet heat) conditions and its degradation products are well resolved from the analyte peaks. Conclusion: This method was successfully validated for accuracy, precision, and linearity. PMID:23781484

  8. Stability Indicating RP-HPLC Method for the Simultaneous Determination of Atorvastatin Calcium, Metformin Hydrochloride, and Glimepiride in Bulk and Combined Tablet Dosage Form

    PubMed Central

    Ramesh, Devi; Habibuddin, Mohammad

    2014-01-01

    A simple, rapid, and precise RP-HPLC method for simultaneous analysis of atorvastatin calcium, metformin hydrochloride, and glimepiride in bulk and its pharmaceutical formulations has been developed and validated. These drugs were separated by using Grace Smart Altima C-8 column (250 × 4.6 mm, 5-μm) with a mobile phase consisting of acetonitrile : phosphate buffer (60 : 40 (v/v), pH 3.0) at a flow rate of 1 mL/min, injection volume 25 µL, and detection at 235 nm. Metformin, atorvastatin, and glimepiride were eluted with retention times of 2.57 min, 7.06 min, and 9.39 min, respectively. The method was validated for accuracy, precision, linearity, specificity, and sensitivity in accordance with ICH (Q2B) guidelines. The results of all the validation parameters were found to be within the acceptable limits. The calibration plots were linear over the concentration ranges from 10 to 150 µg/mL, 20 to 200 µg/mL, and 10 to 150 µg/mL for atorvastatin, metformin, and glimepiride, respectively. The accuracy and precision were found to be between 98.2%–105% and ≤2% for three drugs. Developed method was successfully applied for the determination of the drugs in tablet dosage form and recovery was found to be >98% for three drugs. The degradation products produced as a result of stress studies did not interfere with drug peaks.

  9. Development and Validation of a Stability-Indicating RP-HPLC Method for the Simultaneous Determination of Phenoxyethanol, Methylparaben, Propylparaben, Mometasone Furoate, and Tazarotene in Topical Pharmaceutical Dosage Formulation

    PubMed Central

    Roy, Chinmoy; Chakrabarty, Jitamanyu

    2013-01-01

    A stability-indicating RP-HPLC method has been developed and validated for the simultaneous determination of phenoxyethanol (PE), methylparaben (MP), propylparaben (PP), mometasone furoate (MF), and tazarotene (TA) in topical pharmaceutical dosage formulation. The desired chromatographic separation was achieved on the Waters X-Bridge™ C18 (50×4.6mm, 3.5μ) column using gradient elution at 256 nm detection wavelength. The optimized mobile phase consisted of 0.1%v/v orthophosphoric acid in water as solvent-A and acetonitrile as solvent-B. The method showed linearity over the range of 5.88–61.76 μg/mL, 0.18–62.36 μg/mL, 0.17–6.26 μg/mL, 0.47–31.22 μg/mL, and 0.44–30.45 μg/mL for PE, MP, PP, MF, and TA, respectively. The recovery for all of the components was in the range of 98–102%. The stability-indicating capability of the developed method was established by analysing the forced degradation samples, in which the spectral purity of PE, MP, PP, MF, and TA along with the separation of degradation products from the analyte peaks was achieved. The proposed method was successfully applied for the quantitative determination of PE, MP, PP, MF, and TA in a cream sample. PMID:24482766

  10. Development and Validation of a Stability-Indicating RP-HPLC Method for the Simultaneous Determination of Phenoxyethanol, Methylparaben, Propylparaben, Mometasone Furoate, and Tazarotene in Topical Pharmaceutical Dosage Formulation.

    PubMed

    Roy, Chinmoy; Chakrabarty, Jitamanyu

    2013-12-01

    A stability-indicating RP-HPLC method has been developed and validated for the simultaneous determination of phenoxyethanol (PE), methylparaben (MP), propylparaben (PP), mometasone furoate (MF), and tazarotene (TA) in topical pharmaceutical dosage formulation. The desired chromatographic separation was achieved on the Waters X-Bridge™ C18 (50×4.6mm, 3.5μ) column using gradient elution at 256 nm detection wavelength. The optimized mobile phase consisted of 0.1%v/v orthophosphoric acid in water as solvent-A and acetonitrile as solvent-B. The method showed linearity over the range of 5.88-61.76 μg/mL, 0.18-62.36 μg/mL, 0.17-6.26 μg/mL, 0.47-31.22 μg/mL, and 0.44-30.45 μg/mL for PE, MP, PP, MF, and TA, respectively. The recovery for all of the components was in the range of 98-102%. The stability-indicating capability of the developed method was established by analysing the forced degradation samples, in which the spectral purity of PE, MP, PP, MF, and TA along with the separation of degradation products from the analyte peaks was achieved. The proposed method was successfully applied for the quantitative determination of PE, MP, PP, MF, and TA in a cream sample. PMID:24482766

  11. Identification of Degradation Products and a Stability-Indicating RP-HPLC Method for the Determination of Flupirtine Maleate in Pharmaceutical Dosage Forms

    PubMed Central

    Peraman, Ramalingam; Lalitha, K. V.; Raja, Naga Mallikarjuna; Routhu, Hari Babu

    2014-01-01

    In this stability-indicating, reversed-phase high-performance liquid chromatographic method for flupiritine maleate, forced degradation has been employed and the formed degradants were separated on a C18 column with a 80:20% v/v mixture of methanol-water containing 0.2% (v/v) triethylamine; the pH was adjusted to 3.1. The flow rate was 1 mLmin−1 and the photodiode array detection wavelength was 254 nm. Forced degradation of the drug was carried out under acidic, basic, thermal, photolytic, peroxide, and neutral conditions. Chromatographic peak purity data indicated no co-eluting peaks with the main peaks. This method resulted in the detection of seven degradation products (D1–D7). Among these, three major degradation products from acidic and basic hydrolysis were identified and characterized by 1H-NMR, 13C-NMR, and mass spectral data. The method was validated as per International Conference on Harmonization guidelines (Q2). The linearity of the method was in the concentration range of 20–120 μgmL−1. The relative standard deviations for intra- and interday precision were below 1.5%. The specificity of the method is suitable for the stability-indicating assay. PMID:24959399

  12. Identification of Degradation Products and a Stability-Indicating RP-HPLC Method for the Determination of Flupirtine Maleate in Pharmaceutical Dosage Forms.

    PubMed

    Peraman, Ramalingam; Lalitha, K V; Raja, Naga Mallikarjuna; Routhu, Hari Babu

    2014-06-01

    In this stability-indicating, reversed-phase high-performance liquid chromatographic method for flupiritine maleate, forced degradation has been employed and the formed degradants were separated on a C18 column with a 80:20% v/v mixture of methanol-water containing 0.2% (v/v) triethylamine; the pH was adjusted to 3.1. The flow rate was 1 mLmin(-1) and the photodiode array detection wavelength was 254 nm. Forced degradation of the drug was carried out under acidic, basic, thermal, photolytic, peroxide, and neutral conditions. Chromatographic peak purity data indicated no co-eluting peaks with the main peaks. This method resulted in the detection of seven degradation products (D1-D7). Among these, three major degradation products from acidic and basic hydrolysis were identified and characterized by (1)H-NMR, (13)C-NMR, and mass spectral data. The method was validated as per International Conference on Harmonization guidelines (Q2). The linearity of the method was in the concentration range of 20-120 μgmL(-1). The relative standard deviations for intra- and interday precision were below 1.5%. The specificity of the method is suitable for the stability-indicating assay. PMID:24959399

  13. 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

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

    2013-05-01

    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 μm) 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 μg/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

  14. Development and validation of a RP-HPLC method for stability-indicating assay of gemifloxacin mesylate including identification of related substances by LC-ESI-MS/MS, 1H and 13C NMR spectroscopy.

    PubMed

    Rao, R Nageswara; Naidu, Ch Gangu; Prasad, K Guru; Narasimha, R

    2011-11-01

    A validated stability indicating RP-HPLC assay of gemifloxacin mesylate was developed by separating its related substances on an Inertsil-ODS3V-C18 (4.6 × 250 mm; 5 μm) column using 0.1% trifluoroaceticacid (pH 2.5) and methanol as a mobile phase in a gradient elution mode at a flow rate of 1.0 mL/min at 27°C. The column effluents were monitored by a photodiode array detector set at 287 nm. The method was validated in terms of accuracy, precision and linearity as per ICH guidelines. Forced degradation of gemifloxacin (GFX) was carried out under acidic, basic, thermal, photolysis and peroxide conditions and the degradation products were separated and characterized by ESI-MS/MS, (1) H and (13) C NMR spectroscopy. The method was successfully applied to the analysis of bulk drugs and the recoveries of gemifloxacin and impurities were in the range of 97.60-102.90 and 96.99-102.10%, respectively. No previous reports were found in the literature on identification of degradation products of gemifloxacin. PMID:21370250

  15. Stability indicating RP-HPLC method development and validation for the simultaneous determination of aminexil and minoxidil in pharmaceutical dosage form.

    PubMed

    Siddiraju, S; Sahithi, M

    2015-03-01

    The objective of the present work is to develop stability indicating high-performance liquid chromatographic method for the simultaneous determination of aminexil and minoxidil in pharmaceutical dosage form. The chromatographic separation was achieved with BDS Hypersil C18 column (250 mm×4.6 mm×5 μ) as stationary phase and phosphate buffer and acetonitrile (78:22) as mobile phase. The method was employed by using a flow rate of 1.1 mL/min kept at 30°C. The detection wavelength was kept at 238 nm by using photo-diode array detector. The retention times of the aminexil and minoxidil were found to be 2.3 min and 3.9 min, respectively. The method developed was validated in accordance with ICH guidelines with respect to the stability indicating capacity of the method including system suitability, accuracy, precision, linearity, range, limit of detection, limit of quantification and robustness. The linearity responses of aminexil and minoxidil were found to be in the concentration ranges of 18.75-112.5 μg/mL and 25-150 μg/mL, respectively. The LOD and LOQ values for aminexil were found to be 0.31 and 0.92 μg/mL and minoxidil were found to be 0.03 and 0.10 μg/mL respectively. The percentage recoveries for both the drugs were found in the range of 98-101%. This method is accurate, precise and sensitive; hence, it can be employed for routine quality control of aminexil and minoxidil in pharmaceutical industries and drug testing laboratories. PMID:25542653

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

    PubMed Central

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

    2011-01-01

    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 μm 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

  17. A Validated Stability Indicating RP-HPLC Method for the Determination of Emtricitabine, Tenofovir Disoproxil Fumarate, Elvitegravir and Cobicistat in Pharmaceutical Dosage Form.

    PubMed

    Runja, Chinnalalaiah; Ravi Kumar, Pigili; Avanapu, Srinivasa Rao

    2016-05-01

    A new simple, rapid stability indicating assay method has been developed and validated for the determination of emtricitabine, tenofovir disoproxil fumarate, elvitegravir and cobicistat using reverse-phase high-performance liquid chromatography in their pharmaceutical dosage form. The chromatographic separation was performed on an ODS column (250 × 4.6 mm, 5 µm) using mobile phase A (potassium dihydrogen orthophosphate, pH adjusted to 2.5) and mobile phase B (acetonitrile) in the ratio of 55:45% v/v at a flow rate of 1 mL/min. The analytes were detected at 250 nm. The method was found to be linear in the concentration range of 2-12 µg/mL for EMT, 3-18 µg/mL for TNDF, 1.5-9 µg/mL for ELV and COB, with the coefficient value (R(2)) of >0.9990. The accuracy was measured via recovery studies and found to be acceptable, and the percentage recoveries were found in the range of 99.93-100.08 ± 0.5%. Forced degradation studies were also conducted, and the drugs were subjected to various stress conditions such as acid hydrolysis, base hydrolysis, oxidative, photolytic and thermal degradation. The proposed method was successfully validated and applied for the quantitative estimation of these drugs in both bulk and tablet dosage forms. PMID:26865655

  18. Validated Stability-Indicating RP-HPLC Method for Simultaneous Determination of Clorsulon and Ivermectin Employing Plackett-Burman Experimental Design for Robustness Testing.

    PubMed

    Saad, Ahmed S; Ismail, Nahla S; Soliman, Marwa; Zaazaa, Hala E

    2016-03-01

    A sensitive and highly selective stability-indicating gradient HPLC method was developed and validated for simultaneous determination of clorsulon (CLO) and ivermectin (IVM) in the presence of their degradation products. The drugs were subjected to different stress conditions, including acid and alkaline hydrolysis, oxidative, thermal, and photolytic forced degradation. The robustness of the proposed method was assessed using the Plackett-Burman experimental design, the factors affecting system performance were defined, and nonsignificant intervals for the significant factors were determined. The separation was carried out on a ZORBAX SB phenyl analytical column (250 × 4.6 mm id, 5 μm particle size), with gradient elution utilizing 10 mM sodium dihydrogen phosphate and acetonitrile as mobile phase. UV detection was performed for CLO and IVM at 254 nm over a concentration range of 4-140 and 5-50 μg/mL, respectively, with mean percentage recoveries of 99.90 ± 1.30 and 98.59 ± 1.16%, respectively. The proposed method was successfully applied to a pharmaceutical dosage form containing the investigated drugs. The results were statistically compared with the official HPLC methods, and no significant differences were found. PMID:26997479

  19. LC-MS-MS Characterization of Forced Degradation Products of Fidarestat, a Novel Aldose Reductase Inhibitor: Development and Validation of a Stability-Indicating RP-HPLC Method.

    PubMed

    Talluri, M V N Kumar; Khatoon, Lubna; Kalariya, Pradipbhai D; Chavan, Balasaheb B; Ragampeta, Srinivas

    2015-10-01

    An accurate, precise, robust and selective stability-indicating liquid chromatographic (LC) method has been developed for the monitoring of fidarestat in the presence of its forced degradants. The drug was subjected to hydrolysis (acid, alkali and neutral degradation), oxidation, photolysis and thermal stress conditions. The drug degraded significantly under hydrolytic (basic, acidic and neutral) and oxidative stress conditions, whereas it was found to be stable in photolytic and thermal conditions. The chromatographic separation was achieved on a Grace C18, (250 mm × 4.6 mm × 5 μm) column using gradient mobile phase system consisting of 10 mM of ammonium acetate buffer at pH 4 and acetonitrile at a flow rate of 1 mL/min with UV detection at 283 nm. The developed method was extended to liquid chromatography quadrupole time-of-flight tandem mass spectrometry (LC-QTOF-MS-MS) for characterization of all the degradation products. A total of five new degradation products were identified and characterized by LC-QTOF-MS-MS. The developed LC method was validated as per ICH guideline Q2 (R1). The proposed method was found to be successively applied for the quality control of fidarestat in bulk drug analysis. PMID:26014964

  20. Stability-Indicating RP-HPLC Methods for the Determination of Fluorometholone in Its Mixtures with Sodium Cromoglycate and Tetrahydrozoline Hydrochloride.

    PubMed

    El-Bagary, Ramzia I; Fouad, Marwa A; El-Shal, Manal A; Tolba, Enas H

    2016-07-01

    Two stability-indicating reversed-phase liquid chromatographic methods were developed and validated for the determination of fluorometholone (FLU) in its mixtures with sodium cromoglycate (SCG) and tetrahydrozoline hydrochloride (THZ). The first HPLC method (Method 1) was based on isocratic elution of FLU and SCG along with their alkaline degradation products on a reversed phase C18 column (250 × 4.6 mm id)-ACE Generix 5, using a mobile phase consisting of methanol-water (70 : 30, v/v), pH adjusted to 2.5 using orthophosphoric acid at a flow rate of 1.2 mL min(-1) Quantitation was achieved with UV detection at 240 nm. The second HPLC method (Method 2) was based on isocratic elution of FLU, its alkaline degradation product and THZ on a reversed phase C8 column (250 × 4.6 mm)-ACE Generix 5, using a mobile phase consisting of acetonitrile-50 mM potassium dihydrogen orthophosphate (40 : 60, v/v) at a flow rate of 2 mL min(-1) Quantitation was achieved by applying dual-wavelength detection, where FLU and its alkaline degradation product were detected at 240 nm and THZ was detected at 215 nm at ambient temperatures. Linearity, accuracy and precision were found to be acceptable over the concentration range of 5-50 and 10-500 μg mL(-1) for FLU and SCG (Method 1) and over the concentration range of 5-80 and 5-60 μg mL(-1) for FLU and THZ (Method 2), respectively. Besides, the FLU alkaline degradation product was verified using IR, NMR and LC-MS spectroscopy. The two proposed methods could be successfully applied for the routine analysis of the studied drugs either in their pure bulk powders or in their pharmaceutical preparations without any preliminary separation step. PMID:26921897

  1. Stability-indicating method for simultaneous estimation of olmesartan medoxomile, amlodipine besylate and hydrochlorothiazide by RP-HPLC in tablet dosage form.

    PubMed

    Jain, P S; Patel, M K; Gorle, A P; Chaudhari, A J; Surana, S J

    2012-09-01

    A simple, specific, accurate and precise stability-indicating reversed-phase high-performance liquid chromatographic method was developed for simultaneous estimation of olmesartan medoxomile (OLME), amlodipine besylate (AMLO) and hydrochlorothiazide (HCTZ) in tablet dosage form. The method was developed using an RP C18 base deactivated silica column (250 × 4.6 mm, 5 µm) with a mobile phase consisting of triethylamine (pH 3.0) adjusted with orthophosphoric acid (A) and acetonitrile (B), with a timed gradient program of T/%B: 0/30, 7/70, 8/30, 10/30 with a flow rate of 1.4 mL/min. Ultraviolet detection was used at 236 nm. The retention times for OLME, AMLO and HCTZ were found to be 6.72, 4.28 and 2.30, respectively. The proposed method was validated for precision, accuracy, linearity, range, robustness, ruggedness and force degradation study. The calibration curves of OLME, AMLO and HCTZ were linear over the range of 50-150, 12.5-37.5 and 31-93 µg/mL, respectively. The method was found to be sensitive. The limits of detection of OLME, AMLO and HCTZ were determined 0.19, 0.16 and 0.22 µg/mL and limits of quantification of OLME, AMLO and HCTZ were determined 0.57, 0.49 and 0.66, respectively. Forced degradation study was performed according to International Conference on Harmonization guidelines. PMID:22593253

  2. Quality by Design-Based Development of a Stability-Indicating RP-HPLC Method for the Simultaneous Determination of Methylparaben, Propylparaben, Diethylamino Hydroxybenzoyl Hexyl Benzoate, and Octinoxate in Topical Pharmaceutical Formulation.

    PubMed

    Roy, Chinmoy; Chakrabarty, Jitamanyu

    2014-09-01

    A stability-indicating RP-HPLC method has been developed and validated for the simultaneous determination of methylparaben (MP), propylparaben (PP), diethylamino hydroxybenzoyl hexyl benzoate (DAHHB), and octinoxate (OCT) in topical pharmaceutical formulation. The desired chromatographic separation was achieved on the Kinetex(TM) C18 (250 × 4.6 mm, 5 μm) column using gradient elution at 257 nm detection wavelength. The optimized mobile phase consisted of a buffer : acetonitrile : tetrahydrofuran (60 : 30 : 10, v/v/v) as solvent A and acetonitrile : tetrahydrofuran (70 : 30, v/v) as solvent B. The method showed linearity over the range of 0.19-148.4 μg/mL, 0.23-15.3 μg/mL, 1.97-600.5 μg/mL, and 1.85-451.5 μg/mL for MP, PP, DAHHB, and OCT, respectively. Recovery for all the components was found to be in the range of 98-102%. The stability-indicating capability of the developed method was established by analysing the forced degradation samples in which the spectral purity of MP, PP, DAHHB, and OCT, along with the separation of the degradation products from the analyte peaks, was achieved. The proposed method was successfully applied for the quantitative determination of MP, PP, DAHHB, and OCT in the lotion sample. The design expert with ANOVA software with the linear model was applied and a 2(4) full factorial design was employed to estimate the model coefficients and also to check the robustness of the method. Results of the two-level full factorial design, 2(4) with 20 runs including four centrepoint analysis based on the variance analysis (ANOVA), demonstrated that all four factors, as well as the interactions of resolution between DAHHB and OCT are statistically significant. PMID:25853065

  3. Development and Validation of Stability-Indicating RP-HPLC Method for Simultaneous Determination of Metformin HCl and Glimepiride in Fixed-Dose Combination

    PubMed Central

    Vaingankar, Pradnya N.; Amin, Purnima D.

    2016-01-01

    A simple reversed-phase high-performance liquid chromatography method was developed and validated for simultaneous determination of Metformin hydrochloride (MET) and Glimepiride (GLM) in combination and estimation of their principal degradation products. The separation was achieved using JASCO Finepak SIL (250 mm × 4.6 mm i.d. 5 μm) at ambient temperature. The optimized mobile phase composed of an aqueous phase (20 mM phosphate buffer, adjusted to pH 3.0) and an organic phase (methanol:acetonitrile; 62.5:37.5) in the ratio of 80:20. The flow rate was 1 mL/minute, and the analytes were detected at 230 nm. The developed method was validated for accuracy, precision, specificity, linearity, and sensitivity. The chromatographic analysis time was approximately six minutes with the complete resolution of MET (Rt = 2.75 minutes) and GLM (Rt = 5.87 minutes). The method exhibited good linearity over the range of 5–30 μg/mL for MET and 1–10 μg/mL for GLM. The drugs in combination were subjected to various stress degradation studies as per the International Conference Harmonization (ICH) guidelines. Results obtained from the stress degradation studies revealed that the developed method is applicable for stability studies. PMID:26997866

  4. Development and Validation of Stability-Indicating RP-HPLC Method for Simultaneous Determination of Metformin HCl and Glimepiride in Fixed-Dose Combination.

    PubMed

    Vaingankar, Pradnya N; Amin, Purnima D

    2016-01-01

    A simple reversed-phase high-performance liquid chromatography method was developed and validated for simultaneous determination of Metformin hydrochloride (MET) and Glimepiride (GLM) in combination and estimation of their principal degradation products. The separation was achieved using JASCO Finepak SIL (250 mm × 4.6 mm i.d. 5 μm) at ambient temperature. The optimized mobile phase composed of an aqueous phase (20 mM phosphate buffer, adjusted to pH 3.0) and an organic phase (methanol:acetonitrile; 62.5:37.5) in the ratio of 80:20. The flow rate was 1 mL/minute, and the analytes were detected at 230 nm. The developed method was validated for accuracy, precision, specificity, linearity, and sensitivity. The chromatographic analysis time was approximately six minutes with the complete resolution of MET (Rt = 2.75 minutes) and GLM (Rt = 5.87 minutes). The method exhibited good linearity over the range of 5-30 μg/mL for MET and 1-10 μg/mL for GLM. The drugs in combination were subjected to various stress degradation studies as per the International Conference Harmonization (ICH) guidelines. Results obtained from the stress degradation studies revealed that the developed method is applicable for stability studies. PMID:26997866

  5. Highly efficient, selective, sensitive and stability indicating RP-HPLC-UV method for the quantitative determination of potential impurities and characterization of four novel impurities in eslicarbazepine acetate active pharmaceutical ingredient by LC/ESI-IT/MS/MS.

    PubMed

    Thomas, Saji; Bharti, Amber; Maddhesia, Pawan Kumar; Shandilya, Sanjeev; Agarwal, Ashutosh; Dharamvir; Biswas, Sujay; Bhansal, Vikas; Gupta, Ashish Kumar; Tewari, Praveen Kumar; Mathela, Chandra S

    2012-03-01

    A novel, sensitive, selective and stability indicating LC-UV method was developed for the determination of potential impurities of eslicarbazepine acetate. High performance liquid chromatographic investigation of eslicarbazepine acetate laboratory sample revealed the presence of several impurities. Three impurities were characterized rapidly and four impurities were found to be unknown. The unknown impurities were identified by liquid chromatography coupled with electrospray ionization, ion trap mass spectrometry (LC/ESI-IT/MS/MS). Structural confirmation of these impurities was unambiguously carried out by synthesis followed by characterization using nuclear magnetic resonance spectroscopy (NMR), infrared spectroscopy (FT-IR) and mass spectrometry (MS). Based on the spectroscopic, spectrometric and elemental analysis data unknown impurities were characterized as 5-acetyl-5,11-dihydro-10H-dibenzo [b,f]azepin-10-one, N-acetyl-5H-dibenzo[b,f]azepine-5-carboxamide, 5-acetyl-10,11-dihydro-5H-dibenzo[b,f]azepin-10-yl acetate and 5-acetyl-5H-dibenzo[b,f]azepin-10-yl acetate. The newly developed LC-UV method was validated according to ICH guidelines considering eleven potential impurities and four new impurities to demonstrate specificity, precision, linearity, accuracy and stability indicating nature of the method. The newly developed method was found to be highly efficient, selective, sensitive and stability indicating. A plausible pathway for the formation of four new impurities is proposed. PMID:22178334

  6. Development and Validation of a Novel Stability-Indicating RP-HPLC Method for the Simultaneous Determination of Related Substances of Ketoprofen and Omeprazole in Combined Capsule Dosage Form.

    PubMed

    Koppala, Srinivasarao; Ranga Reddy, V; Anireddy, Jaya Shree

    2016-05-01

    A novel, simple, sensitive, selective and reproducible stability-indicating high performance liquid chromatographic method was developed for the quantitative determination of degradation products and process-related impurities of ketoprofen (KET) and omeprazole (OMZ) in combined oral solid dosage form. Chromatographic separation was achieved on a Phenomenex Luna C18 (2) column (150 × 4.6 mm, 5 μm) under gradient elution by using a binary mixture of potassium dihydrogen phosphate buffer and acetonitrile at a flow rate of 0.8 mL/min. Chromatogram was monitored at 233 nm for KET impurities and at 305 nm for OMZ impurities using a dual wavelength UV detector. Resolution for KET and OMZ and 14 impurities was found to be >1.5 for any pair of components. Typical retention behaviors of impurities at various pH values were depicted graphically. To prove the stability-indicating power of the method, the drug product was subjected to hydrolytic, oxidative, photolytic, humidity and thermal stress conditions as per ICH. The developed method was validated according to the current ICH guidelines for specificity, limit of detection, limit of quantification, linearity, accuracy, precision, ruggedness and robustness. PMID:26860397

  7. Development and Validation of a Stability Indicating RP-HPLC Method for Hydrocortisone Acetate Active Ingredient, Propyl Parahydroxybenzoate and Methyl Parahydroxybenzoate Preservatives, Butylhydroxyanisole Antioxidant, and Their Degradation Products in a Rectal Gel Formulation.

    PubMed

    Ascaso, Magda; Pérez-Lozano, Pilar; García, Mireia; García-Montoya, Encarna; Miñarro, Montse; Ticó, Josep R; Fàbregas, Anna; Carrillo, Carolina; Sarrate, Rocío; Suñé-Negre, Josep M

    2015-01-01

    A stability indicating method was established through a stress study, wherein different methods of degradation (oxidation, hydrolysis, photolysis, and temperature) were studied simultaneously to determine the active ingredient hydrocortisone acetate, preservatives propyl parahydroxybenzoate, and methyl parahydroxybenzoate, antioxidant butylhydroxyanisole (BHA), and their degradation products in a semisolid dosage gel form. The proposed method was suitably validated using a Zorbax SB-Phenyl column and gradient elution. The mobile phase consisted of a mixture of methanol, acetonitrile, and water in different proportions according to a planned program at a flow rate of 1.5 mL/min. The diode array detector was set at 240 nm for the active substance and two preservatives, and 290 nm for BHA. The validation study was conducted according to International Conference on Harmonization guidelines for specificity, linearity, repeatability, precision, and accuracy. The method was used for QC of hydrocortisone acetate gel and for the stability studies with the aim of quantifying the active substance, preservatives, antioxidant, and degradation products. It has proved to be suitable as a fast and reliable method for QC. PMID:25857875

  8. Identification and characterization of stress degradants of lacosamide by LC-MS and ESI-Q-TOF-MS/MS: development and validation of a stability indicating RP-HPLC method.

    PubMed

    Ramisetti, Nageswara Rao; Kuntamukkala, Ramakrishna; Lakshetti, Sridhar; Sripadi, Prabhakar

    2014-07-01

    The current study dealt with the degradation behavior of lacosamide (LAC) under ICH prescribed stress conditions. LAC was found to be labile under acid and base hydrolytic stress conditions, while it was stable to neutral hydrolytic, oxidative, photolytic and thermal stress. In total, seven degradation products (DPs) were formed, which were separated on a C18 column using a stability-indicating method. LC-MS analyses indicated that one of the DPs had the same molecular mass as that of the drug. Structural characterization of DPs was carried out using ESI-Q-TOF-MS/MS technique. The degradation pathways and mechanisms of degradation of the drug were delineated by carrying out the degradation in different co-solvents viz. methanol, deuterated methanol, ethanol, 1-propanol and acetonitrile. The developed LC method was validated for the determination of related substances and assay of LAC as per ICH guidelines. This study demonstrates a comprehensive approach of LAC degradation studies during its development phase. PMID:24699370

  9. New benzimidazole derivatives with potential cytotoxic activity--study of their stability by RP-HPLC.

    PubMed

    Błaszczak-Świątkiewicz, Katarzyna; Mirowski, Marek; Kaplińska, Katarzyna; Kruszyński, Rafał; Trzęsowska-Kruszyńska, Agata; Mikiciuk-Olasik, Elżbieta

    2012-01-01

    Obtained benzimidazole derivatives, our next synthesized heterocyclic compounds, belong to a new group of chemical bondings with potential anticancer properties (Błaszczak-Świątkiewicz & Mikiciuk-Olasik, 2006, J Liguid Chrom Rel Tech 29: 2367-2385; Błaszczak-Świątkiewicz & Mikiciuk-Olasik, 2008, Wiad Chem 62: 11-12, in Polish; Błaszczak-Świątkiewicz & Mikiciuk-Olasik, 2011, J Liguid Chrom Rel Tech 34: 1901-1912). We used HPLC analysis to determine stability of these compounds in 0.2% DMSO (dimethyl sulfoxide). Optimisation of the chromatographic system and validation of the established analytical method were performed. Reversed phases (RP-18) and a 1:1 mixture of acetate buffer (pH 4.5) and acetonitrile as a mobile phase were used for all the analysed compounds at a flow rate 1.0 mL/min. The eluted compounds were monitored using a UV detector, the wavelength was specific for compounds 6 and 9 and compounds 7 and 10. The retention time was specific for all four compounds. The used method was found to have linearity in the concentration range of (0.1 mg/mL-0.1 μg/mL) with a correlation coefficient not less than r(2)=0.9995. Statistical validation of the method proved it to be a simple, highly precise and accurate way to determine the stability of benzimidazole derivatives in 0.2% DMSO. The recoveries of all four compounds examined were in the range 99.24-100.00%. The developed HPLC analysis revealed that the compounds studied remain homogeneous in 0.2% DMSO for up to 96 h and that the analysed N-oxide benzimidazole derivatives do not disintegrate into their analogues - benzimidazole derivatives. Compounds 8, 6 and 9 exhibit the best cytotoxic properties under normoxic conditions when tested against cells of human malignant melanoma WM 115. PMID:22693687

  10. Forced degradation studies of clobetasol 17-propionate in methanol, propylene glycol, as bulk drug and cream formulations by RP-HPLC.

    PubMed

    Fauzee, Ayeshah Fateemah Beebee; Walker, Roderick Bryan

    2013-03-01

    A rapid, simple, stability-indicating forced degradation study of clobetasol 17-propionate was conducted using RP-HPLC. The method was used to analyze clobetasol 17-propionate in methanol, propylene glycol, and a cream formulation. Isocratic elution of clobetasol and its degradation products was achieved using a Nova-Pak® 4 μm C18 150 mm × 3.9 mm id cartridge column and a mobile phase of methanol: water (68:32 v/v) at a flow rate of 0.9 mL min(-1). Quantitation was achieved with UV detection at 239 nm. Nondegraded clobetasol was eluted at a retention time of 6.0 min. Clobetasol 17-propionate was subjected to different stress conditions viz., acidic, basic, heat, oxidation, light, and neutral hydrolysis. The greatest degradation occurred under strong base and oxidative conditions. Strong base-degraded clobetasol produced additional peaks at retention times of 1.8, 4.0, 5.0, and 8.0 min and clobetasol oxidation degradation peaks eluted at 2.2 and 24 min. Complete validation was performed for linearity, accuracy, and precision over the concentration range 0.15-15 μg mL(-1). All data were analyzed statistically and this RP-HPLC method proved to be accurate, precise, linear, and stability indicating for the quantitation of clobetasol 17-propionate in methanol, propylene glycol, and cream formulations. PMID:23355423

  11. Identification of Rhodiola species by using RP-HPLC*

    PubMed Central

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

    2005-01-01

    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 μm 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

  12. Structural Analysis and Quantitative Determination of Clevidipine Butyrate Impurities Using an Advanced RP-HPLC Method.

    PubMed

    Zhou, Yuxia; Zhou, Fan; Yan, Fei; Yang, Feng; Yao, Yuxian; Zou, Qiaogen

    2016-03-01

    Eleven potential impurities, including process-related compounds and degradation products, have been analyzed by comprehensive studies on the manufacturing process of clevidipine butyrate. Possible formation mechanisms could also be devised. MS and NMR techniques have been used for the structural characterization of three previously unreported impurities (Imp-3, Imp-5 and Imp-11). To separate and quantify the potential impurities in a simultaneous fashion, an efficient and advanced RP-HPLC method has been developed. In doing so, four major degradation products (Imp-2, Imp-4, Imp-8 and Imp-10) can be observed under varying stress conditions. This analytical method has been validated according to ICH guidelines with respect to specificity, accuracy, linearity, robustness and stability. The method described has been demonstrated to be applicable in routine quality control processes and stability evaluation studies of clevidipine butyrate. PMID:26489435

  13. Development and validation of a stability-indicating RP-HPLC method for the determination of febuxostat (a xanthine oxidase inhibitor).

    PubMed

    Mukthinuthalapati, Mathrusri Annapurna; Bandaru, Sai Pavan Kumar; Bukkapatnam, Venkatesh; Mohapatro, Chitaranjan

    2013-01-01

    Febuxostat is a selective inhibitor of xanthine oxidase that is used for the treatment of hyperuricaemia in patients with gout. An isocratic liquid chromatographic method was developed and validated for the determination of febuxostat. Chromatographic separation was achieved on a C18 column using sodium acetate buffer (pH 4.0)-acetonitrile (40:60, v/v), with a flow rate 1.2 mL/min (ultraviolet detection at 254 nm). Linearity was observed in the concentration range of 0.1-200 µg/mL (R(2) = 0.9999) with a linear regression equation of y = 21148x - 2025.1. The limit of quantification was found to be 0.0783 µg/mL and the limit of detection was found to be 0.0257 µg/mL. Febuxostat was subjected to stress conditions of degradation in aqueous solutions, including acidic, alkaline, oxidation, photolysis and thermal degradation. The forced degradation studies were performed by using sodium hydroxide, hydrochloric acid, hydrogen peroxide and thermal and ultraviolet radiation. Febuxostat is more sensitive toward acidic conditions than oxidation and very resistant toward alkaline, thermal and photolytic degradations. The method was validated as per the guidelines of the International Conference on Harmonization. The intra-day and inter-day precision (relative standard deviation) was found to be 0.29-0.41 and 0.63-0.76, respectively. The method is simple, specific, precise, robust and accurate for the determination of febuxostat in pharmaceutical dosage forms (tablets). PMID:23204011

  14. Study of RP HPLC Retention Behaviours in Analysis of Carotenoids.

    PubMed

    Ligor, M; Kováčová, J; Gadzała-Kopciuch, R M; Studzińska, S; Bocian, Sz; Lehotay, J; Buszewski, B

    2014-01-01

    For determination of selected carotenoids, various types of columns for high-performance liquid chromatography (HPLC) with different properties have been used. The characteristics of the laboratory-used packing material containing monomeric alkyl-bonded phases (C18, C30) and phenyl as well as phenyl-hexyl stationary phases were studied. The retention data of the examined compounds were used to determine the hydrophobicity and silanol activity of stationary phases applied in the study. The presence of the polar and carboxyl groups in the structure of the bonded ligand strongly influences the polarity of the stationary phase. Columns were compared according to methylene selectivity using a series of benzene homologues. The measurements were done using a methanol-water mobile phase. Knowledge of the properties of the applied stationary phase provided the possibility to predict the RP HPLC retention behaviours in analysis of carotenoids including lutein, lycopene and β-carotene. The composition of the mobile phase, the addition of triethylamine and the type of stationary phase had been taken into account in designing the method of carotenoid identification. Also a monolithic column characterised by low hydrodynamic resistance, high porosity and high permeability was applied. The presented results show that the coverage density of the bonded ligands on silica gel packings and length of the linkage strongly influence the carotenoid retention behaviours. In our study, the highest retention parameters for lutein, lycopene and β-carotene were observed for C30 and C18 stationary phase. This effect corresponds with pore size of column packing greater than 100 Å and carbon content higher than 11 %. PMID:25089049

  15. Development and validation of RP-HPLC method to determine anti-allergic compound in Thai traditional remedy called Benjalokawichien.

    PubMed

    Sakpakdeejaroen, Intouch; Juckmeta, Thana; Itharat, Arunporn

    2014-08-01

    Benjalokawichien (BLW) or Ya-Ha-Rak (HR) is a traditional remedy in the Nationaldrug list of herbal medicinal products AD 2012 of Thailand. For traditional use, BLW is used as antipyretic agent. It also has anti-allergic effect, particularly treating allergic rash. The ethanolic extract of BLW exhibited anti-allergic activity via inhibitory effect against a release ofbeta-hexosaminidase in RBL-2H3 cell line. Pectolinarigenin has been identified as the active compound ofBLW extract. In this study, a reversed-phase high performance liquid chromatography (RP-HPLC) method was developed in order to control quality ofpreparation in three aspects such as chemical fingerprint, quantification and stability of the ethanolic extract. The RP-HPLC was performed with a gradient mobile phase composed of 0.1% ortho phosphoric acid and acetronitrile, and peaks were detected at 331 nm. Based on validation results, this analytical method is precise, accurate and stable for quantitative determination ofpectolinarigenin. The amount ofpectolinarigenin in Benjalokawichien extract determined by this method was 18.50 mg/g ofextract. Therefore, this method could be consideredfor quality control ofBLWextract. PMID:25518297

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

    PubMed

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

    2006-02-15

    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

  17. Cerebral nuclei distribution study of dehydrodiisoeugenol as an anxiogenic agent determined by RP-HPLC.

    PubMed

    Zhang, You-Bo; Zhu, Li-Qiao; Yang, Xiu-Wei

    2013-01-01

    A sensitive RP-HPLC-DAD method was established to quantify dehydrodiisoeugenol (DDIE) in rat cerebral nuclei. The assay procedure involved one-step extraction of DDIE and daidzein, as an internal standard, from rat plasma and various cerebral nuclei with ethyl acetate. Chromatographic separation was performed on a Diamonsil™ ODS C(18) column with methanol-water (81:19, v/v) as a mobile phase. The UV absorbance of the samples was measured at the wavelength of 270nm. The analysis method was proved to be precise and accurate at linearity ranges in plasma and each cerebral nucleus with correlation coefficients of ≥0.9971. The results indicated that the method established was successfully applied to cerebral nuclei distribution study of DDIE after intravenous administration at a single dose of 40mg/kg to rat. DDIE showed high concentration in all of cerebral nuclei at 8min, which indicated that DDIE could cross the blood-brain barrier rapidly and might be one of the main bioactive substances of nutmeg. The results provide fundamental data for evaluating the effects of DDIE on the central nervous system and to be developed into an effective anxiogenic agent. PMID:23059843

  18. FTIR assay method for UV inactive drug carisoprodol and identification of degradants by RP-HPLC and ESI-MS.

    PubMed

    Acharya, Pratap Chandra; Vasi, Ruqaiya; Suares, Divya

    2016-09-01

    A new method of analysis has been developed for UV inactive drug carisoprodol using FTIR spectroscopy. These methods were validated for various parameters according to ICH guidelines. The proposed method has also been successfully applied for the determination of the drug concentration in a tablet formulation. The method proved to be accurate (mean percentage recovery between 95 and 105%), precise and reproducible (relative standard deviation<2%), while being simple, economical and less time consuming than other methods and can be used for routine estimation of carisoprodol in the pharmaceutical industry. The developed method also implicates its utility for other UV inactive substances. The stability of the drug under various stress conditions was studied and the drug was found to be particularly susceptible to alkaline hydrolysis. Degradation products of the alkaline hydrolysis were detected by RP-HPLC and tentatively identified by ESI-MS. PMID:27398631

  19. HPTLC and RP-HPLC methods for simultaneous determination of Paracetamol and Pamabrom in presence of their potential impurities.

    PubMed

    Abdelaleem, Eglal A; Naguib, Ibrahim A; Hassan, Eman S; Ali, Nouruddin W

    2015-10-10

    Two chromatgraphic methods were developed for determination of Paracetamol (PCM) and Pamabrom (PAM) in presence of P-aminophenol (PAP) and Theophylline (THEO) as potential impurities of both drugs respectively. First method is HPTLC which depends on separation and quantitation of the studied drugs on aluminum plates pre-coated with silica gel 60 F₂₅₄ as a stationary phase using chloroform:methanol:ethyl acetate:glacial acetic acid (8:0.8:0.6:0.2, v/v/v/v) as mobile phase followed by densitometric measurement of the bands at 254 nm. Second method is RP-HPLC which comprises separation of the studied drugs on a Phenomenex C8 column by gradient elution using mobile phase consisting of sodium dihydrogen phosphate buffer (0.05 M): methanol:acetonitrile (85:10:5, v/v/v) at a flow rate of 1 mL/min for first 7.5 min and (70:20:10, v/v/v) at a flow rate of 1.5 mL/min for the next 5 min. The proposed methods were successfully applied for determination of the potential impurities of PCM and PAM after resolving them from the pure drugs. The developed methods have been validated and proved to meet the requirements delineated by ICH guidelines with respect to linearity, accuracy, precision, specificity and robustness. The validated methods were successfully applied for determination of the studied drugs in their pharmaceutical formulation. The results were statistically compared to those obtained by the reported RP-HPLC method where no significant difference was found; indicating the ability of proposed methods to be used for routine quality control analysis of these drugs. PMID:26001162

  20. 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

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

    2014-01-01

    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 μm, Phenomenex Inc.) column at ambient temperature was maintained. The method showed excellent linear response with correlation coefficient (R (2)) values of 0.999 and 1.0 for paracetamol and ibuprofen respectively, which were within the limit of correlation coefficient (R (2) > 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. PMID:25452691

  1. 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

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

    2014-01-01

    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 μm, 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. PMID:25452691

  2. A stability-indicating HPLC method for medroxyprogesterone acetate in bulk drug and injection formulation.

    PubMed

    Burana-Osot, Jankana; Ungboriboonpisal, Sooksri; Sriphong, Lawan

    2006-03-18

    A stability-indicating HPLC assay method has been developed and validated for medroxyprogesterone acetate (MPA) in bulk drug and injectable suspension. An isocratic RP-HPLC was achieved on a Hichrom C(18) column (150 mm x 4.6mm i.d., 5 microm) utilizing a mobile phase of methanol 0.020 M acetate buffer pH 5 (65:35, v/v) and a photodiode array detector at 245 nm. The stress testing of MPA was carried out under acidic and alkaline hydrolysis, and oxidation conditions. MPA was well resolved from its degradation products, a main related substance (megestrol acetate) and two preservatives (methyl paraben and propyl paraben) with the resolution >or=2. The proposed method was validated for selectivity, linearity, accuracy, precision and solution stability. The method was found to be suitable for the quality control of MPA in bulk drug and injections as well as the stability-indicating studies. PMID:16242876

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

    PubMed

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

    2014-01-01

    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

  4. Monitoring seasonal variation of epicatechin and gallic acid in the bark of Saraca asoca using reverse phase high performance liquid chromatography (RP-HPLC) method

    PubMed Central

    Ketkar, Pushkar M.; Nayak, Shraddha U.; Pai, Sandeep R.; Joshi, Rajesh K.

    2015-01-01

    Background: Saraca asoca (Roxb.) Wilde (Fabaceae) is a high valued but vulnerable medicinal plant of Western Ghats region. This plant is mainly known for its use in various gynecological disorders. Objective: The objective of the present study was to investigate seasonal variation of the polyphenolic compounds viz., epicatechin and gallic acid in the bark of S. asoca by using Reverse Phase High Performance Liquid Chromatography-Diode Array Detector (RP-HPLC-DAD) method. Materials and Methods: The bark was collected in six different Ritu (season) viz. Varsha (monsoon), Sharad (autumn), hemant (early winter), Shishir (winter), Vasanta (spring), and Grishma (summer) mentioned in Ayurveda. Results: The RP-HPLC-DAD analysis indicated that levels of epicatechin and gallic acid in the bark of S. asoca vary seasonally. The highest concentration of epicatechin was observed in Shishir Ritu (3315.19 ± 165.76 mg/100g) and gallic acid during Hemant Ritu (211.90 ± 10.60 mg/100 g). Conclusions: In present study, the ability to synthesize and accumulate both the compounds in bark of S. asoca varied greatly throughout the seasons. It was also observed that the compound epicatechin was present abundantly as compared to gallic acid throughout the seasons. PMID:25878461

  5. Validated RP-HPLC and TLC-Densitometric Methods for Analysis of Ternary Mixture of Cetylpyridinium Chloride, Chlorocresol and Lidocaine in Oral Antiseptic Formulation.

    PubMed

    Abdelwahab, Nada S; Ali, Nouruddin W; Abdelkawy, M; Emam, Aml A

    2016-03-01

    This work was concerned with development, optimization, application and validation of reversed phase high performance liquid chromatography (RP-HPLC) and thin layer chromatography (TLC)-densitometric methods for analysis of cetylpyridinium chloride, chlorocresol and lidocaine in Canyon(®) gel. The first developed RP-HPLC method depended on chromatographic separation on a ZORBAX Eclipse Plus C8 column, with elution with a mobile phase consisting of 0.05% phosphoric acid solution : acetonitrile : methanol (15 : 24 : 61, by volume), pumping the mobile phase at a flow rate of 1.00 mL min(-1), with ultraviolet detection at 220 nm. While in the subsequently developed method, the TLC-densitometric method, complete separation of the studied mixture was achieved using methanol : acetone : acetic acid (7 : 3 : 0.2, by volume) as a mobile phase, aluminum plates precoated with silica gel 60 F254 as a stationary phase and 215 nm as the scanning wavelength. Factors affecting the developed methods were studied and optimized; moreover, methods had been validated as per the International Conference of Harmonization guideline and the results indicated that the suggested methods were reproducible, reliable and applicable for rapid routine analysis. Statistical comparison of the two developed methods with the reported HPLC ones using F- and Student's t tests showed no significant difference. PMID:26363491

  6. A sensitive and practical RP-HPLC-FLD for determination of the low neuroactive amino acid levels in body fluids and its application in depression.

    PubMed

    Wu, Juan-Li; Yu, Si-Yang; Wu, Shi-Hua; Bao, Ai-Min

    2016-03-11

    Ion-exchange high performance liquid chromatography (HPLC) generally fails as a method to determine low levels of free amino acids (AAs) in body fluids. Here we present a modified reversed-phase HPLC (RP-HPLC) protocol for the determination of AAs in body fluids and its application in mood disorder patients. We improved a previous research protocol by modifying i) sample preparation, including deproteination, ii) derivitization, including derivating agent and condition, and iii) sample separation, which is mainly determined by the pH value, the components and the additives of the mobile phases. The combination of these modifications, together with fluorescence detection (FLD), allows sensitive and practical determination of free AA levels in body fluids of depressive patients. This protocol was validated by determining the postmortem cerebrospinal fluid (CSF) glutamic acid (Glu) and γ-aminobutyric acid (GABA) levels of 8 major depressive disorder (MDD) patients, 9 bipolar disorder (BD) patients, and 19 well-matched controls, while also testing the plasma and CSF AA levels of living MDD patients. CSF Glu and GABA levels were both significantly decreased in MDD but not in BD patients. The data indicate that this RP-HPLC-FLD protocol is applicable for detection of low levels of neuroactive AAs in body fluids, as well as for routine clinical applications. PMID:26808642

  7. Use of thiolysis hyphenated to RP-HPLC-ESI(-)-MS/MS for the analysis of flavanoids in fresh lager beers.

    PubMed

    Callemien, Delphine; Guyot, Sylvain; Collin, Sonia

    2008-10-15

    Proanthocyanidins are well known for their involvement in haze and colour development during beer ageing. New methodologies are needed, however, to understand what happens to them in the bottled beer. For the first time in the brewing field, thiolysis was hyphenated to RP-HPLC-ESI(-)-MS/MS to investigate these flavanoids. Thirty minutes at 40°C followed by 10h at room temperature emerged as the best conditions for complete depolymerisation. NP-HPLC-ESI(-)-MS/MS was used to quantify and isolate fractions from monomers to trimers in a Sephadex LH20 acetone/water (70/30, v/v) beer extract. Unsurprisingly, a lower dimer/monomer ratio was evidenced in PVPP-treated beers than in silica gel-filtered beers. Most beer dimers are procyanidins B3 (two catechin units) whilst most trimers are prodelphinidins (catechin in terminal units and gallocatechins or catechins in extension units). Gallocatechin appeared to come mainly from malt. Despite the absence of chromatographic peaks corresponding to oligomers above trimers, an apparent degree of polymerisation close to six was calculated in the total LH20 extract. Still higher mean degrees of polymerisation (mDPs) were calculated for malt and hop, indicating selective extraction or depolymerisation from raw materials to beer. The main part of beer polyphenols is composed of complex undefined structures not degraded by toluene-α-thiol. PMID:26047295

  8. A direct RP-HPLC method for the determination of furanic aldehydes and acids in honey.

    PubMed

    Spano, Nadia; Ciulu, Marco; Floris, Ignazio; Panzanelli, Angelo; Pilo, Maria I; Piu, Paola C; Salis, Severyn; Sanna, Gavino

    2009-04-15

    In this study 5-hydroxymethyl-2-furaldehyde (HMF), 2-furaldehyde, 3-furaldehyde, 2-furoic acid and 3-furoic acid are contemporarily determined in honey using a swift and direct RP-HPLC approach. The validation protocol was performed in terms of detection and quantification limits, precision (by repeatability and reproducibility), linearity and accuracy (by recovery tests); the acceptability of the precision and accuracy results was positively verified using Horwitz's model and AOAC guidelines, respectively. The method was tested on 18 honey samples of different ages, and botanical and geographical origin. HMF and 2-furaldehyde correlated highly with the age of the samples, whereas no correlation was observed with regards to 2-furaldehyde and 2-furoic acid. Hypotheses relating to the formation of minority furanic compounds are also proposed. PMID:19174244

  9. [Determination of 7 bio-active alkaloids in Stephania plants by RP-HPLC].

    PubMed

    Huang, J; Guo, J; Duan, G

    1998-07-01

    Seven bio-active alkaloids (stepholidine, sinoacutine, isocorydine, l-tetrahydropalmatine, crebanine, fanchinoline and tetrandrine) in Stephania plants were determined by RP-HPLC, using UV detection (282 nm) and gradient elution. The reversed phase system consisted of ODS column and methanol-water-triethylamine as mobile phase. The flow rate was 1.0 ml.min-1. Good linearity between peak heights and concentrations of the alkaloids was obtained in the concentration range. The HPLC method proved accurate, precise and sensitive. The results showed that there were some differences in the occurrence and content of the alkaloids between various species and between the same species from different habitats and collecting time. Based on the results, some species with high content of the 7 bio-active alkaloids were selected. The study provided some useful information for the utilization of medicinal plant resources in the genus Stephania. PMID:12016887

  10. Stability indicating studies on NMITLI 118RT+ (standardized extract of withania somnifera dunal)

    PubMed Central

    Ahmad, Hafsa; Khandelwal, Kiran; Pachauri, Shakti Deep; Sanghwan, Rajender Singh; Dwivedi, Anil Kumar

    2014-01-01

    Background: Withania somnifera Dunal (Ashwagandha) is an Indian medicinal plant of great medicinal value; used in many clinically proven conditions. NMITLI-118RT+ is a candidate drug under a Council of Scientific and Industrial Research (CSIR) networking project. It is a chemotype of W. somnifera's root extract, which has been used for the present study. Objectives: The present investigation aims to develop and validate a simple isocratic reverse phase-high performance liquid chromatography (RP-HPLC) system for the detection and estimation of Withanolide A (marker compound) and its analytical application for stability indicating studies on NMITLI-118RT+. Material and Methods: A validated RP-HPLC method for Withanolide A was established on a Waters HPLC system and the same was used on NMITLI-118RT+ for quantification and fingerprinting purposes, and for establishing forced degradation, isothermal stress tests, and drug-excipient testing protocols as per International Conference on Harmonization (ICH) guidelines. Results: A validated method was established, which could detect the marker at a retention time of around 6.3 minutes, with a linearity range of 2-100 μg/mL, by varying the amounts of the said marker, which were estimated in four different batches of NMITLI-118RT+. Photostability as per ICH guidelines suggested a slight loss of the active constituent and maximum degradation was afforded with alkali followed by acid, and then peroxide, in the forced degradation studies. In the drug-excipient studies, the maximum amount of active constituent could be detected in the samples with ethyl cellulose and the least with hydroxy propyl cellulose. Conclusion: The method developed here was simple and rapid. The various stability indicating studies carried out in the present investigation would be useful for formulation development and were suggestive of deciding the recommended storage conditions for NMITLI-118RT+. PMID:25210308

  11. Development of Novel RP-HPLC Method for Separation and Estimation of Critical Geometric Isomer and Other Related Impurities of Tafluprost Drug Substance and Identification of Major Degradation Compounds by Using LC-MS.

    PubMed

    Sreenivasulu, J; Venkata Ramana, P; Sampath Kumar Reddy, G; Rakesh, M; Nagaraju, Ch V S; Thirumalai Rajan, S; Eswaraiah, S; Kishore, M; Ramakrishna, M

    2016-09-01

    A novel, simple, sensitive and stability-indicating reverse-phase high-performance liquid chromatography (RP-HPLC) method was developed and validated for the quantitative determination of the geometric isomer (Trans) and other related substances in the active pharmaceutical ingredient (API) of Tafluprost (TFL), with their determination by an assay. A chromatographic separation of TFL and its impurities was achieved with a C18 analytical column, using gradient elution with mobile phase A consisting of a mixture of water, methanol and orthophosphoric acid (900:100:1, v/v) and mobile phase B consisting of a mixture of acetonitrile and water (900:100, v/v). The instrumental settings included a flow rate of 1.0 mL/min for related substances and 1.2 mL/min for the assay, a column temperature of 50°C and a detector wavelength of 210 nm, using a photodiode array detector. TFL was exposed to thermal, photolytic, hydrolytic and oxidative stress conditions and the stressed samples were analyzed by the proposed method. Peak homogeneity data of TFL were obtained by using a photodiode array detector in the stressed sample chromatograms, which demonstrated the specificity of the method for estimation in the presence of degradants. The developed method was validated for parameters such as precision, accuracy, linearity, limit of detection, limit of quantification, ruggedness and robustness as per ICH guidelines. PMID:27226462

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

    PubMed Central

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

    2011-01-01

    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 μm, 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 μg/ml for NAP and 2-10 μg/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

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

    PubMed Central

    Li, Ying-hua; Lu, Xiu-yang

    2005-01-01

    The origin of 5-HMF (5-hydroxymethyl-2-furaldehyde) in a Shengmaiyin decoction was investigated by the RP-HPLC method below. A C18 column (250 mm×4.6 mm, i.d. 5 μm) with a column temperature of 25 °C was used. The mobile phase was a mixture of ultra-pure water-acetonitrile (95:5, V/V) and the flow rate was 1.0 ml/min. The detection wavelength was 280 nm. The injection volume was 1 μl and the running time was about 20 min. The addition of Schisandra was regulated to assess the contribution of an acid environment to the production of 5-HMF. In order to confirm the role of saccharides in the production of 5-HMF, different amount of fructose was used. The 5-HMF level in decoctions of processed and unprocessed Schisandra was investigated in order to determine the origin of 5-HMF. The results showed that 5-HMF was derived mainly from the decoction of Schisandra only and not the mixed decoction of Ophionpogon and Schisandra. The appearance of 5-HMF is not simply the result of the decomposition of saccharides under the acid environment created by Schisandra, but the processing procedure plays an important role in the production of 5-HMF. PMID:16187416

  14. Occurrence and behavior of system peaks in RP HPLC with solely aqueous mobile phases.

    PubMed

    Kalíková, Kveta; Hruska, Vlastimil; Svobodová, Jana; Chudoba, Richard; Gas, Bohuslav; Tesarová, Eva

    2009-09-01

    System peaks are important but often also disturbing phenomena occurring in separation systems. Behavior of system peaks was studied in reversed phase high performance liquid chromatography (RP HPLC) systems consisting of an RP Amide C16 column and aqueous solutions of organic acids with alkaline metal hydroxides as mobile phases. Binary mobile phases, composed of benzoic acid and lithium hydroxide (LiOH) or cesium hydroxide (CsOH), yielded two system peaks. The first peak was stationary and the second one moved with dilution of the mobile phase or with changes of the alkaline metal hydroxide concentration. The latter changes affected dissociation of the benzoic acid present in the mobile phase and thereby its retention. The presumption that the first system peak is not influenced by the type of alkaline metal cation and that it is related to the non-adsorbed component of the mobile phase was confirmed by a cyclic procedure. Three-component mobile phases composed of benzoic acid, tropic acid, and a hydroxide gave rise to three system peaks as expected. The first peak was again stationary and the two others shifted depending on the concentration variation of both acids. Resonance causing a zigzag peak, well described in capillary zone electrophoresis (CZE), was observed if 1-pentanol was injected into a chromatographic system with one-component mobile phase. PMID:19639550

  15. RP-HPLC analysis of flucloxacillin in human plasma: validation and application to a bioequivalence study.

    PubMed

    Zhou, Q; Ruan, Z; Yuan, H; Jiang, B; Xu, D

    2007-02-01

    A RP-HPLC method with rapid sample processing was developed for quantitation of flucloxacillin in human plasma using dicloxacillin as the internal standard. The plasma sample (100 microL) was acidified with glacial acetic acid, and deproteinized by precipitation with acetonitrile. The supernatant was directly injected into the HPLC system. Separation was achieved on an Alltima C18 column (250 mmx4.6 mm I.D., 5 microm), with a mixture of 10 mmol x L(-1) KH2PO4-acetonitrile (64.5:35.5, v/v) as mobile phase. The assay was successfully applied to a randomized, two-period cross-over bioequivalence study in 20 healthy Chinese volunteers following a single oral dose of 250 mg flucloxacillin capsules. A non-compartmental method was used for pharmacokinetic analysis. Compared with data in the literature, flucloxacillin was eliminated more slowly in Chinese than in Caucasians. Cmax, AUC(0-t) and AUC(0-infinity) were tested for bioequivalence after log-transformation of data. No significant difference was found. Tmax was analyzed by Wilcoxon's test and no significant difference was obtained (P > 0.05). Based on these statistical inferences, the two formulations were judged to be bioequivalent and, thus, can be prescribed interchangeably. PMID:17341027

  16. Dissemination of the highly expressed Bx7 glutenin subunit (Glu-B1al allele) in wheat as revealed by novel PCR markers and RP-HPLC.

    PubMed

    Butow, B J; Gale, K R; Ikea, J; Juhász, A; Bedö, Z; Tamás, L; Gianibelli, M C

    2004-11-01

    Increased expression of the high molecular weight glutenin subunit (HMW-GS) Bx7 is associated with improved dough strength of wheat (Triticum aestivum L.) flour. Several cultivars and landraces of widely different genetic backgrounds from around the world have now been found to contain this so-called 'over-expressing' allelic form of the Bx7 subunit encoded by Glu-B1al. Using three methods of identification, SDS-PAGE, RP-HPLC and PCR marker analysis, as well as pedigree information, we have traced the distribution and source of this allele from a Uruguayan landrace, Americano 44D, in the mid-nineteenth century. Results are supported by knowledge of the movement of wheat lines with migrants. All cultivars possessing the Glu-B1al allele can be identified by the following attributes: (1) the elution of the By sub-unit peak before the Dx sub-unit peak by RP-HPLC, (2) high expression levels of Bx7 (>39% Mol% Bx), (3) a 43 bp insertion in the matrix-attachment region (MAR) upstream of the gene promoter relative to Bx7 and an 18 bp nucleotide duplication in the coding region of the gene. Evidence is presented indicating that these 18 and 43 bp sequence insertions are not causal for the high expression levels of Bx7 as they were also found to be present in a small number of hexaploid species, including Chinese Spring, and species expressing Glu-B1ak and Glu-B1a alleles. In addition, these sequence inserts were found in different isolates of the tetraploid wheat, T. turgidum, indicating that these insertion/deletion events occurred prior to hexaploidization. PMID:15340686

  17. An Experimental Design Approach for Impurity Profiling of Valacyclovir-Related Products by RP-HPLC.

    PubMed

    Katakam, Prakash; Dey, Baishakhi; Hwisa, Nagiat T; Assaleh, Fathi H; Chandu, Babu R; Singla, Rajeev K; Mitra, Analava

    2014-09-01

    Impurity profiling has become an important phase of pharmaceutical research where both spectroscopic and chromatographic methods find applications. The analytical methodology needs to be very sensitive, specific, and precise which will separate and determine the impurity of interest at the 0.1% level. Current research reports a validated RP-HPLC method to detect and separate valacyclovir-related impurities (Imp-E and Imp-G) using the Box-Behnken design approach of response surface methodology. A gradient mobile phase (buffer: acetonitrile as mobile phase A and acetonitrile: methanol as mobile phase B) was used. Linearity was found in the concentration range of 50-150 μg/mL. The mean recovery of impurities was 99.9% and 103.2%, respectively. The %RSD for the peak areas of Imp-E and Imp-G were 0.9 and 0.1, respectively. No blank interferences at the retention times of the impurities suggest the specificity of the method. The LOD values were 0.0024 μg/mL for Imp-E and 0.04 μg/mL for Imp-G and the LOQ values were obtained as 0.0082 μg/mL and 0.136 μg/mL, respectively, for the impurities. The S/N ratios in both cases were within the specification limits. Proper peak shapes and satisfactory resolution with good retention times suggested the suitability of the method for impurity profiling of valacyclovir-related drug substances. PMID:25853072

  18. An Experimental Design Approach for Impurity Profiling of Valacyclovir-Related Products by RP-HPLC

    PubMed Central

    Katakam, Prakash; Dey, Baishakhi; Hwisa, Nagiat T; Assaleh, Fathi H; Chandu, Babu R; Singla, Rajeev K; Mitra, Analava

    2014-01-01

    Abstract Impurity profiling has become an important phase of pharmaceutical research where both spectroscopic and chromatographic methods find applications. The analytical methodology needs to be very sensitive, specific, and precise which will separate and determine the impurity of interest at the 0.1% level. Current research reports a validated RP-HPLC method to detect and separate valacyclovir-related impurities (Imp-E and Imp-G) using the Box-Behnken design approach of response surface methodology. A gradient mobile phase (buffer: acetonitrile as mobile phase A and acetonitrile: methanol as mobile phase B) was used. Linearity was found in the concentration range of 50–150 μg/mL. The mean recovery of impurities was 99.9% and 103.2%, respectively. The %RSD for the peak areas of Imp-E and Imp-G were 0.9 and 0.1, respectively. No blank interferences at the retention times of the impurities suggest the specificity of the method. The LOD values were 0.0024 μg/mL for Imp-E and 0.04 μg/mL for Imp-G and the LOQ values were obtained as 0.0082 μg/mL and 0.136 μg/mL, respectively, for the impurities. The S/N ratios in both cases were within the specification limits. Proper peak shapes and satisfactory resolution with good retention times suggested the suitability of the method for impurity profiling of valacyclovir-related drug substances. PMID:25853072

  19. Development and Validation of an RP-HPLC Method for Quantitative Estimation of Eslicarbazepine Acetate in Bulk Drug and Tablets

    PubMed Central

    Singh, M.; Kumar, L.; Arora, P.; Mathur, S. C.; Saini, P. K.; Singh, R. M.; Singh, G. N.

    2013-01-01

    A convenient, simple, accurate, precise and reproducible RP-HPLC method was developed and validated for the estimation of eslicarbazepine acetate in bulk drug and tablet dosage form. Objective was achieved under optimised chromatographic conditions on Dionex RP-HPLC system with Dionex C18 column (250×4.6 mm, 5 μm particle size) using mobile phase composed of methanol and ammonium acetate (0.005 M) in the ratio of 70:30 v/v. The separation was achieved using an isocratic elution method with a flow rate of 1.0 ml/ min at room temperature. The effluent was monitored at 230 nm using diode array detector. The retention time of eslicarbazepine acetate is found to be 4.9 min and the standard calibration plot was linear over a concentration range of 10-90 μg/ml with r2=0.9995. The limit of detection and quantification were found to be 3.144 and 9.52 μg/ml, respectively. The amount of eslicarbazepine acetate in bulk and tablet dosage form was found to be 99.19 and 97.88%, respectively. The method was validated statistically using the percent relative standard deviation and the values are found to be within the limits. The recovery studies were performed and the percentage recoveries were found to be 98.33± 0.5%. PMID:24591752

  20. Development and Validation of an RP-HPLC Method for Quantitative Estimation of Eslicarbazepine Acetate in Bulk Drug and Tablets.

    PubMed

    Singh, M; Kumar, L; Arora, P; Mathur, S C; Saini, P K; Singh, R M; Singh, G N

    2013-11-01

    A convenient, simple, accurate, precise and reproducible RP-HPLC method was developed and validated for the estimation of eslicarbazepine acetate in bulk drug and tablet dosage form. Objective was achieved under optimised chromatographic conditions on Dionex RP-HPLC system with Dionex C18 column (250×4.6 mm, 5 μm particle size) using mobile phase composed of methanol and ammonium acetate (0.005 M) in the ratio of 70:30 v/v. The separation was achieved using an isocratic elution method with a flow rate of 1.0 ml/ min at room temperature. The effluent was monitored at 230 nm using diode array detector. The retention time of eslicarbazepine acetate is found to be 4.9 min and the standard calibration plot was linear over a concentration range of 10-90 μg/ml with r(2)=0.9995. The limit of detection and quantification were found to be 3.144 and 9.52 μg/ml, respectively. The amount of eslicarbazepine acetate in bulk and tablet dosage form was found to be 99.19 and 97.88%, respectively. The method was validated statistically using the percent relative standard deviation and the values are found to be within the limits. The recovery studies were performed and the percentage recoveries were found to be 98.33± 0.5%. PMID:24591752

  1. Improved RP-HPLC method to determine biapenem in human plasma/urine and its application to a pharmacokinetic study.

    PubMed

    Zhao, Libo; Liu, Yi; Kou, Zhibin; Bayasi, Aidijie; Cai, Huan; Zhang, Chunyan; Wang, Qian; Li, Yuzhen; Fang, Yi

    2011-01-01

    Existing methods to determine biapenem (CAS 120410-24-4), a carbapenem, either lacked sensitivity/reproducibility or had no internal standard as a control. Here an improved reversed-phase high-performance liquid chromatographic (RP-HPLC) method was established in human plasma and urine. After adding p-aminobenzoic acid as the internal standard to plasma or urine, plasma samples were ultra-filtrated and urine samples were diluted directly. Chromatographic separations were carried out on a 4.6 mm x 150 mm column with acetonitrile-0.1 mol/l sodium acetate (2:98, v:v; pH 4.38 or 4.00) as mobile phase and UV detection at 300 nm. The extraction recovery was 91.51% for biapenem at the concentration level of 5 microg /ml in human plasma. The linear quantification range of the method was 0.1 to approximately 50 microg /ml for plasma and urine, with linear correlation coefficients greater than 0.998. The intra-day and inter-day relative standard deviations (R.S.D.) for biapenem at low, middle and high levels in human samples were less than 12.51% for plasma and less than 7.05% for urine. The RP-HPLC method was successfully applied to pharmacokinetic studies, in which healthy subjects received multiple doses of biapenem (300 mg, i.v., b.i.d., for 5 continuous days). The pharmacokinetic results are presented. PMID:21528646

  2. Characterization of potential degradation products in a PEGylating reagent 20 kDa monomethoxy polyethylene glycol propionaldehyde by RP-HPLC, APCI-MS and NMR.

    PubMed

    Zhang, Heidi; Wilson, John; Zhang, Jifeng; Luo, Ying

    2014-02-01

    Ensuring quality of PEGylating reagents is essential for the successful development and manufacturing of PEGylated biopharmaceuticals. However, little is known about how to maintain and verify the quality of PEG raw materials for PEGylated protein manufacturing. In this study, monomethoxy polyethylene glycol propionaldehyde (mPEG-aldehyde) was subjected to conditions that mimic accelerated stability conditions. Separation of trace-level degradation products in the presence of mPEG-aldehyde was achieved by derivatization with 2,4-dinitrophenylhydrazine (DNPH), followed by reversed phase high performance liquid chromatography with ultraviolet detection (RP-HPLC-UV) at 355nm. Structural characterization by atmospheric pressure chemical ionization mass spectrometry (APCI-MS) identified formaldehyde, acetaldehyde, crotonaldehyde, acrolein, benzaldehyde, and tolualdehyde as major degradation products or process-related impurities. The presence of formaldehyde and acrolein was confirmed by (1)H NMR in the forced degraded mPEG-aldehyde samples without derivatization of mPEG-aldehyde. Findings from this study imply that reactive impurities could form as a result of inappropriate mPEG-aldehyde handling or storage. Further, a rapid screening method based on reversed phase HPLC was shown to be an effective screening assay used for routine screening of mPEG-aldehyde to ensure consistent PEGylated protein product quality. PMID:24316423

  3. Stability-Indicating Assay for the Determination of Pentobarbital Sodium in Liquid Formulations.

    PubMed

    Ajemni, Myriam; Balde, Issa-Bella; Kabiche, Sofiane; Carret, Sandra; Fontan, Jean-Eudes; Cisternino, Salvatore; Schlatter, Joël

    2015-01-01

    A stability-indicating assay by reversed-phase high performance liquid chromatography (RP-HPLC) method was developed for the determination of pentobarbital sodium in oral formulations: a drug used for infant sedation in computed tomography (CT) or magnetic resonance imaging (MRI) scan. The chromatographic separation was achieved on a reversed-phase C18 column, using isocratic elution and a detector set at 214 nm. The optimized mobile phase consisted of a 0.01 M potassium buffer pH 3 and methanol (40 : 60, v/v). The flow rate was 1.0 mL/min and the run time of analysis was 5 min. The linearity of the method was demonstrated in the range of 5 to 250 μg/mL pentobarbital sodium solution (r (2) = 0.999). The limit of detection and limit of quantification were 2.10 and 3.97 μg/mL, respectively. The intraday and interday precisions were less than 2.1%. Accuracy of the method ranged from 99.2 to 101.3%. Stability studies indicate that the drug is stable to sunlight and in aqueous solution. Accelerated pentobarbital sodium breakdown by strong alkaline, acidic, or oxidative stress produced noninterfering peaks. This method allows accurate and reliable determination of pentobarbital sodium for drug stability assay in pharmaceutical studies. PMID:26543481

  4. Quantification of 4'-geranyloxyferulic acid (GOFA) in honey samples of different origin by validated RP-HPLC-UV method.

    PubMed

    Genovese, Salvatore; Taddeo, Vito Alessandro; Fiorito, Serena; Epifano, Francesco

    2016-01-01

    Natural honey has been employed as a nutraceutical agent with benefits and therapeutic promises for humans for many centuries. It has been largely used as food and medicine by all generations, traditions, and civilizations, both ancient and modern. Several chemicals having beneficial effects for human health have been reported as components of natural honey and these include sugars, organic acids, aminoacids, minerals, and vitamins. Also some important phytochemicals have been described and these comprise tannins, flavonoids, terpenes, saponins, and alkaloids. In this note it is described the successful application of a RP HPLC-UV-vis method for the separation and quantification of 4'-geranyloxyferulic acid (GOFA) in four honey samples of different origin. Concentration values showed a great variation between the four samples tested, being chestnut honey the one richest in GOFA (7.87 mg/g). The findings described herein represent the first example reported in the literature of the characterization of an oxyprenylated phenylpropanoid in honey. PMID:26421962

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

    PubMed Central

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

    2012-01-01

    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

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

    PubMed

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

    2012-01-01

    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

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

    PubMed

    Bhosale, Suryakant D; Rajput, Sadhana J

    2011-01-01

    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

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

    PubMed Central

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

    2013-01-01

    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

  9. Development and Validation of a RP-HPLC Method for Determination of Related Substances and Degradants in Entacapone.

    PubMed

    Purnachand, Dasari; Veerareddy, Arava; Ramadevi, Bhoomireddy; Kameswarrao, Ch V S L; Madhusudhanreddy, Bethi

    2016-09-01

    A new reverse phase-liquid chromatography (RP-HPLC) method has been developed for simultaneous determination of entacapone and its pharmacopoeia impurities, in-house impurities and degradation impurities (total 17 analytes). Chromatographic separation was achieved on a C18 column (size: 250 × 4.6 mm; 5 µm particle size) at a flow rate of 1.0 mL/min with 210 nm detection. The mobile phase (MP) consists of 1.361 g of potassium di-hydrogen phosphate and 1.742 g of di-potassium phosphate in 1.0 L water, pH adjusted to 2.5 with ortho phosphoric acid (MP-A) and acetonitrile (MP-B) through gradient elution. The product was subjected to stress conditions such as acid, base, peroxide, thermal and photolytic degradation. Two new impurities above 2% level were observed and isolated through preparative HPLC and well characterized. However, no interference observed due to degradation impurities and entacapone and its EP impurities, in-house impurities. As part of the method validation, specificity, limit of detection, limit of quantitation (LOQ), linearity, accuracy, precision, robustness and ruggedness were determined. LOQ values were achieved between 0.01 and 0.04%. Good linearity (r(2) > 0.99) was obtained ranging from LOQ to 150%. Recovery was verified for all impurities at concentrations ranging from LOQ to 150%. Hence, a newly developed RP-HPLC method was capable for well separation of all analytes with acceptable resolution and tailing factor. PMID:27165569

  10. Concurrent estimation of amlodipine besylate, hydrochlorothiazide and valsartan by RP-HPLC, HPTLC and UV-spectrophotometry.

    PubMed

    Sharma, Manish; Kothari, Charmy; Sherikar, Omkar; Mehta, Priti

    2014-01-01

    Accurate, sensitive and reproducible reversed-phase high-performance liquid chromatography (RP-HPLC), high-performance thin-layer chromatography (HPTLC) and ultraviolet (UV) spectrophopometric methods were developed for the concurrent estimation of amlodipine besylate (AMLO), hydrochlorothiazide (HCTZ) and valsartan (VALS) in bulk and combined tablet dosage forms. For the RP-HPLC method, separation was achieved on a C18 column using potassium dihydrogen orthophosphate buffer (50 mM, pH 3.7) with 0.2% triethylamine as the modifier and acetonitrile in the ratio of 56:44 (v/v) as the mobile phase. Quantification was achieved using a photodiode array detector at 232 nm over a concentration range of 2-25 µg/mL for AMLO, 5-45 µg/mL for HCTZ and 20-150 µg/mL for VALS. For the HPTLC method, the drugs were separated by using ethyl acetate-methanol-toluene-ammonia (7.5:3:2:0.8, v/v/v/v) as the mobile phase. Quantification was achieved using UV detection at 242 nm over a concentration range of 100-600 ng/spot for AMLO, 150-900 ng/spot for HCTZ and 1,200-3,200 ng/spot for VALS. The UV-spectrophotometric simultaneous equation method was based on the measurement of absorbance at three wavelengths; i.e., at 237.6 nm (λmax of AMLO), 270.2 nm (λmax of HCTZ) and 249.2 nm (λmax of VALS) in methanol. Quantification was achieved over the concentration range of 2-20 µg/mL for AMLO, 5-25 µg/mL HCTZ and 10-50 µg/mL for VALS. All methods were validated according to International Conference on Harmonization guidelines and successfully applied to marketed pharmaceutical formulations. Additionally, the three methods were compared statistically by an analysis of variance test, which revealed no significant difference between the proposed methods with respect to accuracy and precision. PMID:23293040

  11. Development and Validation of Stability-indicating HPLC Method for Simultaneous Estimation of Cefixime and Linezolid

    PubMed Central

    Patel, Nidhi S.; Tandel, Falguni B.; Patel, Yogita D.; Thakkar, Kartavya B.

    2014-01-01

    A stability-indicating reverse phase high performance liquid chromatography method was developed and validated for cefixime and linezolid. The wavelength selected for quantitation was 276 nm. The method has been validated for linearity, accuracy, precision, robustness, limit of detection and limit of quantitation. Linearity was observed in the concentration range of 2-12 μg/ml for cefixime and 6-36 μg/ml for linezolid. For RP-HPLC, the separation was achieved by Phenomenex Luna C18 (250×4.6 mm) 5 μm column using phosphate buffer (pH 7):methanol (60:40 v/v) as mobile phase with flow rate 1 ml/min. The retention time of cefixime and linezolid were found to be 3.127 min and 11.986 min, respectively. During force degradation, drug product was exposed to hydrolysis (acid and base hydrolysis), H2O2, thermal degradation and photo degradation. The % degradation was found to be 10 to 20% for both cefixime and linezolid in the given condition. The method specifically estimates both the drugs in presence of all the degradants generated during forced degradation study. The developed methods were simple, specific and economic, which can be used for simultaneous estimation of cefixime and linezolid in tablet dosage form. PMID:25593387

  12. Development and Validation of Stability-indicating HPLC Method for Simultaneous Estimation of Cefixime and Linezolid.

    PubMed

    Patel, Nidhi S; Tandel, Falguni B; Patel, Yogita D; Thakkar, Kartavya B

    2014-01-01

    A stability-indicating reverse phase high performance liquid chromatography method was developed and validated for cefixime and linezolid. The wavelength selected for quantitation was 276 nm. The method has been validated for linearity, accuracy, precision, robustness, limit of detection and limit of quantitation. Linearity was observed in the concentration range of 2-12 μg/ml for cefixime and 6-36 μg/ml for linezolid. For RP-HPLC, the separation was achieved by Phenomenex Luna C18 (250×4.6 mm) 5 μm column using phosphate buffer (pH 7):methanol (60:40 v/v) as mobile phase with flow rate 1 ml/min. The retention time of cefixime and linezolid were found to be 3.127 min and 11.986 min, respectively. During force degradation, drug product was exposed to hydrolysis (acid and base hydrolysis), H2O2, thermal degradation and photo degradation. The % degradation was found to be 10 to 20% for both cefixime and linezolid in the given condition. The method specifically estimates both the drugs in presence of all the degradants generated during forced degradation study. The developed methods were simple, specific and economic, which can be used for simultaneous estimation of cefixime and linezolid in tablet dosage form. PMID:25593387

  13. Simultaneous quantitative determination of nine active chemical compositions in traditional Chinese medicine Glycyrrhiza by RP-HPLC with full-time five-wavelength fusion method.

    PubMed

    Wu, Yin-Ping; Meng, Xian-Sheng; Bao, Yong-Rui; Wang, Shuai; Kang, Ting-Guo

    2013-01-01

    A new, simple, accurate and reliable full-time five-wavelength fusion method for the simultaneous separation and determination of nine active chemical compositions (liquiritin apioside, liquiritin, isoliquiritin apioside, ononin, isoliquiritin, liquiritigenin, calycosin, isoliquiritigenin, Glycyrrhizic acid monoammonium salt) in traditional Chinese medicine Glycyrrhiza was developed using reverse phase high-performance liquid chromatography (RP-HPLC) coupled with a diode-array detector (DAD). The chromatographic separation was performed on an Agilent TC-C18 column with gradient elution using 0.04% methanoic acid (A) and acetonitrile (B) at a flow rate of 1.0 mL min(-1) and UV detection at 248 nm, 250 nm, 276 nm, 362 nm, 370 nm. The standard curves were linear over the range of 2.1379-12.8272 μg for liquiritin apioside, 3.9299-23.5794 μg for liquiritin, 1.0432-6.2592 μg for isoliquiritin apioside, 0.8764-5.8584 μg for ononin, 1.0701-6.4205 μg for isoliquiritin, 1.3685-8.2111 μg for liquiritigenin, 0.3927-2.3563 μg for calycosin, 0.2498- 1.4986 μg for isoliquiritigenin, 2.0094-12.0564 μg for Glycyrrhizic acid monoammonium salt, respectively (r(2) > 0.9997). The recoveries and relative standard deviation (RSD) varied from 95.09% to 103.54% and 1.09% to 2.36%, respectively. The precision for all the analytes was less than 2.52%. The method indicated good performance in terms of precision, accuracy and linearity. The method enabled the simultaneous determination of nine active chemical compositions for quality control of Glycyrrhiza. PMID:23336517

  14. Comparison of RP-HPLC modes to analyse the N-glycome of the free-living nematode Pristionchus pacificus.

    PubMed

    Yan, Shi; Wilson, Iain B H; Paschinger, Katharina

    2015-06-01

    Pristionchus pacificus is a free-living nematode increasingly used as an organism for comparison to the more familiar model Caenorhabditis elegans. In this study, we examined the N-glycans of this organism isolated after serial release with peptide:N-glycosidases F and A; after fluorescent labelling with 2-aminopyridine, chromatographic fractionation by three types of RP-HPLC (with either classical C18, fused core C18 or alkylamide-bonded phases) followed by mass spectrometric analyses revealed key features of its N-glycome. In addition to paucimannosidic and oligomannosidic glycans typical of invertebrates, N-glycans with two core fucose residues were detected. Furthermore, a range of glycans carrying up to three phosphorylcholine residues was observed whereas, unlike C. elegans, no tetrafucosylated N-glycans were detected. Structures with three fucose residues, unusual methylation of core α1,3-fucose or with galactosylated fucose motifs were found in low amounts; these features may correlate with a different ensemble or expression of glycosyltransferase genes as compared to C. elegans. From an analytical perspective, both the alkylamide RP-amide and fused core C18 columns, as compared to a classical C18 material, offer advantages in terms of resolution and of elution properties, as some minor pyridylamino-labelled glycans (e.g. those carrying phosphorylcholine) appear in earlier fractions and so potential losses of such structures due to insufficient gradient length can be avoided. PMID:25639343

  15. A validated RP-HPLC method for quantitative determination of related impurities of ursodeoxycholic acid (API) by refractive index detection.

    PubMed

    Peepliwal, Ashok; Bonde, C G; Bothara, K G

    2011-03-25

    An isocratic RP-HPLC method was developed and validated for quantitative determination of ursodeoxycholic acid (UDCA) and its related impurities. Considering the lower molecular absorptivity of UDCA, refractive index detector was used to detect the impurities on a Phenomenex Luna C(18), 150 mm × 4.6 mm, 5 μm column. The mobile phase was 0.1% acetic acid/methanol (30:70, v/v) and flow rate was 0.8 ml/min. The detector and column temperature was maintained at 40°C. The method is linear over a range of 0.25-3.5 μg/ml for all impurities and coefficient of correlation (r(2)) was ≥0.9945. The accuracy of method demonstrated at three levels in the range of 50-150% of the specification limit and recoveries were found to be in the range of 97.11-100.75%. The precision for all related impurities was below 3.5% R.S.D. The method was applied to commercial bulk drug sample for assay purpose. PMID:21095088

  16. Biodiversity of Salix spp. honeydew and nectar honeys determined by RP-HPLC and evaluation of their antioxidant capacity.

    PubMed

    Tuberoso, Carlo I G; Jerković, Igor; Bifulco, Ersilia; Marijanović, Zvonimir

    2011-05-01

    Rare unifloral willow (Salix spp.) honeys obtained from nectar or honeydew were investigated by direct RP-HPLC-DAD method in order to identify and quantify compounds that can be used as possible markers of their origin. Antioxidant and antiradical activities of willow honeys were evaluated using FRAP (=ferric reducing antioxidant assay) and DPPH (=1,1-diphenyl-2-picrylhydrazyl radical) tests, respectively. Also HMF (=5-(hydroxymethyl)furfural), diastase activity, and CIE L*a*b*C*h* chromatic coordinates were evaluated. Abscisic acids (ABA) are typical of willow nectar honey, with a predominance of (Z,E)-ABA on (E,E)-ABA (98.2 and 31.7 mg/kg, resp.). Kinurenic acid and salicylic acid are useful to mark willow honeydew honey. The proposed HPLC-DAD method proved to be easy and reliable to identify the two different Salix spp. honeys, being not affected from any sample preparation artifact. Total antioxidant activity measured with the FRAP assay ranged from 3.2 to 12.6 mmol Fe(2+) /kg, and the antiradical activity measured with the DPPH assay ranged from 0.6 to 3.0 mmol TEAC (=Trolox equivalent antioxidant capacity)/kg in nectar and honeydew honeys, respectively. Salix spp. nectar and honeydew honeys proved to be two completely different honeys, because, besides color attributes, they show different antioxidant properties and specific compounds. PMID:21560235

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

    PubMed Central

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

    2011-01-01

    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 μm) 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 μg/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 μg. The proposed method can be used for routine analysis of ethacridine lactate in bulk drug and pharmaceutical formulation. PMID:23781440

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

    PubMed

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

    2011-04-01

    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 μm) 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 μg/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 μg. The proposed method can be used for routine analysis of ethacridine lactate in bulk drug and pharmaceutical formulation. PMID:23781440

  19. Enantioseparation of Citalopram by RP-HPLC, Using Sulfobutyl Ether-β-Cyclodextrin as a Chiral Mobile Phase Additive

    PubMed Central

    Peng, Yangfeng; He, Quan Sophia; Cai, Jiang

    2016-01-01

    Enantiomeric separation of citalopram (CIT) was developed using a reversed phase HPLC (RP-HPLC) with sulfobutylether-β-cyclodextrin (SBE-β-CD) as a chiral mobile phase additive. The effects of the pH value of aqueous buffer, concentration of chiral additive, composition of mobile phase, and column temperature on the enantioseparation of CIT were investigated on the Hedera ODS-2 C18 column (250 mm × 4.6 mm × 5.0 um). A satisfactory resolution was achieved at 25°C using a mobile phase consisting of a mixture of aqueous buffer (pH of 2.5, 5 mM sodium dihydrogen phosphate, and 12 mM SBE-β-CD), methanol, and acetonitrile with a volumetric ratio of 21 : 3 : 1 and flow rate of 1.0 mL/min. This analytical method was evaluated by examining the precision (lower than 3.0%), linearity (regression coefficients close to 1), limit of detection (0.070 µg/mL for (R)-CIT and 0.076 µg/mL for (S)-CIT), and limit of quantitation (0.235 µg/mL for (R)-CIT and 0.254 µg/mL for (S)-CIT). PMID:26880921

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

    PubMed

    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

    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

  1. Enantioseparation of Citalopram by RP-HPLC, Using Sulfobutyl Ether-β-Cyclodextrin as a Chiral Mobile Phase Additive.

    PubMed

    Peng, Yangfeng; He, Quan Sophia; Cai, Jiang

    2016-01-01

    Enantiomeric separation of citalopram (CIT) was developed using a reversed phase HPLC (RP-HPLC) with sulfobutylether-β-cyclodextrin (SBE-β-CD) as a chiral mobile phase additive. The effects of the pH value of aqueous buffer, concentration of chiral additive, composition of mobile phase, and column temperature on the enantioseparation of CIT were investigated on the Hedera ODS-2 C18 column (250 mm × 4.6 mm × 5.0 um). A satisfactory resolution was achieved at 25°C using a mobile phase consisting of a mixture of aqueous buffer (pH of 2.5, 5 mM sodium dihydrogen phosphate, and 12 mM SBE-β-CD), methanol, and acetonitrile with a volumetric ratio of 21 : 3 : 1 and flow rate of 1.0 mL/min. This analytical method was evaluated by examining the precision (lower than 3.0%), linearity (regression coefficients close to 1), limit of detection (0.070 µg/mL for (R)-CIT and 0.076 µg/mL for (S)-CIT), and limit of quantitation (0.235 µg/mL for (R)-CIT and 0.254 µg/mL for (S)-CIT). PMID:26880921

  2. Biochemical characterization of two crotamine isoforms isolated by a single step RP-HPLC from Crotalus durissus terrificus (South American rattlesnake) venom and their action on insulin secretion by pancreatic islets.

    PubMed

    Toyama, M H; Carneiro, E M; Marangoni, S; Barbosa, R L; Corso, G; Boschero, A C

    2000-03-01

    Crotamine, a neurotoxin present in the venom of the South American rattlesnake Crotalus durrisus terrificus exists as several polymorphic variants, as demonstrated by recombinant DNA technology (Smith and Schmidt, Toxicon 28 (1990) 575-585). We have isolated native crotamine by chromatography on Sephadex G75, and have purified two crotamine isoforms (F2 and F3) by a single step of RP-HPLC. Native crotamine and RP-HPLC fractions F2 and F3 produced skeletal muscle spasms and spastic paralysis in mice. At low glucose concentrations (2.8-5.6 mmol/l), none of the crotamines altered the insulin secretion by rat isolated islets. In the presence of 16.7 mmol glucose/l, F2 (5 microg/ml), but not F3, increased insulin secretion two-fold, whereas native crotamine (1.5, 5 and 16.5 microg/ml) potentiated the secretion dose-dependently. The increase in insulin secretion induced by F2 fraction (5 microg/ml) was similar to that obtained with 16.5 microg of native crotamine/ml. These results indicate that the mode of action of the F2 and F3 isoforms in beta-cells is different from that in muscle cells. This difference may be related to the binding affinity of each isoform for the Na(+) channels located in the beta-cell membrane. Crotamine isoforms may be valuable tools for studying the involvement of Na(+) channels in the mechanism of insulin secretion. PMID:10699490

  3. Stability-Indicating HPLC Method for Simultaneous Determination of Chloramphenicol, Dexamethasone Sodium Phosphate and Tetrahydrozoline Hydrochloride in Ophthalmic Solution

    PubMed Central

    AlAani, Hashem; Alnukkary, Yasmin

    2016-01-01

    Purpose: A simple stability-indicating RP-HPLC assay method was developed and validated for quantitative determination of Chloramphenicol, Dexamethasone Sodium Phosphate and Tetrahydrozoline Hydrochloride in ophthalmic solution in the presence of 2-amino-1-(4-nitrophenyl)propane-1,3-diol, a degradation product of Chloramphenicol, and Dexamethasone, a degradation product of Dexamethasone Sodium Phosphate. Methods: Effective chromatographic separation was achieved using C18 column (250 mm, 4.6 mm i.d., 5 μm) with isocratic mobile phase consisting of acetonitrile - phosphate buffer (pH 4.0; 0.05 M) (30:70, v/v) at a flow rate of 1 mL/minute. The column temperature was maintained at 40°C and the detection wavelength was 230 nm. Results: The proposed HPLC procedure was statistically validated according to the ICH guideline, and was proved to be stability-indicating by resolution of the APIs from their forced degradation products. Conclusion: The developed method is suitable for the routine analysis as well as stability studies. PMID:27123429

  4. Simultaneous determination of chloramphenicol, dexamethasone and naphazoline in ternary and quaternary mixtures by RP-HPLC, derivative and wavelet transforms of UV ratio spectra

    NASA Astrophysics Data System (ADS)

    Hoang, Vu Dang; Hue, Nguyen Thu; Tho, Nguyen Huu; Nguyen, Hue Minh Thi

    2015-03-01

    The application of chemometrics-assisted UV spectrophotometry and RP-HPLC to the simultaneous determination of chloramphenicol, dexamethasone and naphazoline in ternary and quaternary mixtures is presented. The spectrophotometric procedure is based on the first-order derivative and wavelet transforms of ratio spectra using single, double and successive divisors. The ratio spectra were differentiated and smoothed using Savitzky-Golay filter; whereas wavelet transform realized with wavelet functions (i.e. db6, gaus5 and coif3) to obtain highest spectral recoveries. For the RP-HPLC procedure, the separation was achieved on a ZORBAX SB-C18 (150 × 4.6 mm; 5 μm) column at ambient temperature and the total run time was less than 7 min. A mixture of acetonitrile - 25 mM phosphate buffer pH 3 (27:73, v/v) was used as the mobile phase at a flow rate of 1.0 mL/min and the effluent monitored by measuring absorbance at 220 nm. Calibration graphs were established in the range 20-70 mg/L for chloramphenicol, 6-14 mg/L for dexamethasone and 3-8 mg/L for naphazoline (R2 > 0.990). The RP-HPLC and ratio spectra transformed by a combination of derivative-wavelet algorithms proved to be able to successfully determine all analytes in commercial eye drop formulations without sample matrix interference (mean percent recoveries, 97.4-104.3%).

  5. Protein separation and characterization by np-RP-HPLC followed by intact MALDI-TOF mass spectrometry and peptide mass mapping analyses

    PubMed Central

    Dauly, Claire; Perlman, David H.; Costello, Catherine E.; McComb, Mark E.

    2008-01-01

    Due to their complexity, the separation of intact proteins from complex mixtures is an important step to comparative proteomics and the identification and characterization of the proteins by mass spectrometry (MS). In the study reported, we evaluated the use of non-porous-reversed-phase (np-RP) HPLC for intact protein separation prior to MS analyses. The separation system was characterized and compared to 1D-SDS-PAGE electrophoresis in terms of resolution and sensitivity. We demonstrate that np-RP HPLC protein separation is highly reproducible and provides intact protein fractions which can be directly analyzed by MALDI-TOF MS for intact molecular weight determination. An in-well digestion protocol was developed, allowing for rapid protein identification by peptide mass fingerprinting (PMF) and resulted in comparable or improved peptide recovery compared with in-gel digestion. The np-RP sensitivity of detection by UV absorbance at 214 nm for intact proteins was at the low ng level and the sensitivity of peptide analysis by MALDI-TOF MS was in the 10–50 pg level. A membrane protein fraction was characterized to demonstrate application of this methodology. Among the identified proteins, multiple forms of vimentin were observed. Overall we demonstrate that np-RP HPLC followed by MALDI-TOF MS allows for rapid, sensitive and reproducible protein fractionation and very specific protein characterization by integration of PMF analysis with MS intact molecular weight information. PMID:16823977

  6. Using UV-absorbance of intrinsic dithiothreitol (DTT) during RP-HPLC as a measure of experimental redox potential in vitro.

    PubMed

    Seo, Angie; Jackson, Janelle L; Schuster, Jolene V; Vardar-Ulu, Didem

    2013-07-01

    Many in-vitro experiments performed to study the response of thiol-containing proteins to changes in environmental redox potentials use dithiothreitol (DTT) to maintain a preset redox environment throughout the experiments. However, the gradual oxidation of DTT during the course of the experiments, and the interaction between DTT and other components in the system, can significantly alter the initial redox potential and complicate data interpretation. Having an internal reporter of the actual redox potential of the assayed sample facilitates direct correlation of biochemical findings with experimental redox status. Reversed-phase high-performance liquid chromatography (RP-HPLC) is a widely used, well-established tool for analysis and purification of biomolecules, including proteins and peptides. Here, we describe a simple, robust, and quantitative RP-HPLC method we developed and tested for determination of the experimental redox potential of an in-vitro sample at the time of the experiment. It exploits the specific UV-absorbance of the oxidized intrinsic DTT in the samples and retains the high resolving power and high sensitivity of RP-HPLC with UV detection. PMID:23743664

  7. Simultaneous determination of chloramphenicol, dexamethasone and naphazoline in ternary and quaternary mixtures by RP-HPLC, derivative and wavelet transforms of UV ratio spectra.

    PubMed

    Hoang, Vu Dang; Hue, Nguyen Thu; Tho, Nguyen Huu; Nguyen, Hue Minh Thi

    2015-03-15

    The application of chemometrics-assisted UV spectrophotometry and RP-HPLC to the simultaneous determination of chloramphenicol, dexamethasone and naphazoline in ternary and quaternary mixtures is presented. The spectrophotometric procedure is based on the first-order derivative and wavelet transforms of ratio spectra using single, double and successive divisors. The ratio spectra were differentiated and smoothed using Savitzky-Golay filter; whereas wavelet transform realized with wavelet functions (i.e. db6, gaus5 and coif3) to obtain highest spectral recoveries. For the RP-HPLC procedure, the separation was achieved on a ZORBAX SB-C18 (150×4.6 mm; 5 μm) column at ambient temperature and the total run time was less than 7 min. A mixture of acetonitrile - 25 mM phosphate buffer pH 3 (27:73, v/v) was used as the mobile phase at a flow rate of 1.0 mL/min and the effluent monitored by measuring absorbance at 220 nm. Calibration graphs were established in the range 20-70 mg/L for chloramphenicol, 6-14 mg/L for dexamethasone and 3-8 mg/L for naphazoline (R(2)>0.990). The RP-HPLC and ratio spectra transformed by a combination of derivative-wavelet algorithms proved to be able to successfully determine all analytes in commercial eye drop formulations without sample matrix interference (mean percent recoveries, 97.4-104.3%). PMID:25546493

  8. Simple and rapid RP-HPLC method for simultaneous determination of acyclovir and zidovudine in human plasma.

    PubMed

    Sharma, Megha; Nautiyal, Pragya; Jain, Surendra; Jain, Deepti

    2010-01-01

    Combination therapy with acyclovir and zidovudine is used for the treatment of herpes-infected immunocompromised patients. In the view of the optimal drug concentrations (minimum effective concentrations) for viral suppression and avoidance of drug toxicity, monitoring of drug levels has been considered essential to determine drug concentrations in plasma after administration of a dose of acyclovir and zidovudine. A simple, precise, and rapid RP-HPLC method has been developed for this purpose. Chromatographic separation was performed using methanol-water (50 + 50, v/v), pH 2.5 adjusted with orthophosphoric acid, as an isocratic mobile phase at a flow rate of 0.8 mL/min with an Inertsil ODS (C18) column (5 microm particle size, 250 x 4.60 mm id). Detection was carried out using a UV photo diode array detector at 258 nm. The plasma samples were prepared by a protein precipitation method. The retention time for acyclovir and zidovudine was 3.5 +/- 0.2 and 6.2 +/- 0.3 min, respectively. The method was linear in the range of 200-1800 and 400-3600 ng/mL with LOQ of 200 ng (SD = +/-1.4) and 400 ng (SD = +/-0.9) for zidovudine and acyclovir, respectively, in plasma. The mean accuracy was 98.0 and 96.4%, with average extraction recovery of 64.8 +/- 2.1 and 77.5 +/- 1.7% for lower nominal concentrations of acyclovir and zidovudine, respectively. PMID:21140658

  9. Simultaneous Estimation of Withaferin A and Z-Guggulsterone in Marketed Formulation by RP-HPLC.

    PubMed

    Agrawal, Poonam; Vegda, Rashmi; Laddha, Kirti

    2015-07-01

    A simple, rapid, precise and accurate high-performance liquid chromatography (HPLC) method was developed for simultaneous estimation of withaferin A and Z-guggulsterone in a polyherbal formulation containing Withania somnifera and Commiphora wightii. The chromatographic separation was achieved on a Purosphere RP-18 column (particle size 5 µm) with a mobile phase consisting of Solvent A (acetonitrile) and Solvent B (water) with the following gradients: 0-7 min, 50% A in B; 7-9 min, 50-80% A in B; 9-20 min, 80% A in B at a flow rate of 1 mL/min and detection at 235 nm. The marker compounds were well separated on the chromatogram within 20 min. The results obtained indicate accuracy and reliability of the developed simultaneous HPLC method for the quantification of withaferin A and Z-guggulsterone. The proposed method was found to be reproducible, specific, precise and accurate for simultaneous estimation of these marker compounds in a combined dosage form. The HPLC method was appropriate and the two markers are well resolved, enabling efficient quantitative analysis of withaferin A and Z-guggulsterone. The method can be successively used for quantitative analysis of these two marker constituents in combination of marketed polyherbal formulation. PMID:25572656

  10. RP-HPLC analysis of seco-iridoid glycoside swertiamarin from different Swertia species.

    PubMed

    Kshirsagar, Parthraj R; Pai, Sandeep R; Nimbalkar, Mansingraj S; Gaikwad, Nikhil B

    2016-01-01

    Genus Swertia is valued for its great medicinal potential; mainly Swertia chirayita (Roxb. ex Fleming) H. Karst. is used in traditional medicine for a wide range of diseases. Seco-iridoid glycosides like swertiamarin is referred with enormous pharmacological potentials. The aim of the study was to identify a suitable substitute to S. chirayita by quantifying seco-iridoid swertiamarin from five different Swertia species endemic to the Western Ghats. The reverse-phase high-performance liquid chromatography diode array detector analyses were performed and chromatographic separation was achieved on a Lichrospher 100, C18e (5 µm) column (250-4.6 mm). A mobile phase consisting of acetonitrile and water (25:75) was used for separation. Results indicated that the concentration of the marker compound has been found to vary largely between and within the species from different localities. The content of swertiamarin was the highest in S. chirayita compared to the other species studied herein, advocating the use of Swertia minor as an alternate source to S. chirayita. PMID:26299409

  11. Development and validation of a stability-indicating HPLC method for determination of voriconazole and its related substances.

    PubMed

    Gu, Ping; Li, Yuru

    2009-08-01

    An isocratic reversed-phase high performance liquid chromatographic (RP-HPLC) method has been developed and validated for the determination of voriconazole and its related substances. The drug substance was subjected to stress conditions of UV light, water hydrolysis, acid, base, oxidation, and deoxidization to observe the degradation products. The successful separation of voriconazole from its synthetic impurities and degradation products formed under stress conditions was achieved using an Agilent Zorbax SB-C18 (250mm x 4.6 mm i.d., 5 microm) column maintained at 25 degrees C with a mobile phase of a mixture of ammonium phosphate dibasic buffer (pH adjusted to 6.0 using diluted orthophosphoric acid; 50 mM)-acetonitrile (52:48, v/v). The mobile phase flow rate was 1.0 mL/min, and the detection wavelength was 250 nm. The stress sample solutions were assayed against the qualified reference standard of voriconazole and the mass balance in each case was close to 99.7%, confirming its stability-indication capacity. The developed HPLC method was validated with respect to linearity, accuracy, precision, specificity, and robustness. The developed HPLC method to determine the related substances and assay determination of voriconazole can be used to evaluate the quality of regular production samples. It can be also used to test the stability samples of voriconazole. PMID:19772734

  12. Validation and Uncertainty Estimation of an Ecofriendly and Stability-Indicating HPLC Method for Determination of Diltiazem in Pharmaceutical Preparations

    PubMed Central

    Sadeghi, Fahimeh; Navidpour, Latifeh; Bayat, Sima; Afshar, Minoo

    2013-01-01

    A green, simple, and stability-indicating RP-HPLC method was developed for the determination of diltiazem in topical preparations. The separation was based on a C18 analytical column using a mobile phase consisted of ethanol: phosphoric acid solution (pH = 2.5) (35 : 65, v/v). Column temperature was set at 50°C and quantitation was achieved with UV detection at 240 nm. In forced degradation studies, the drug was subjected to oxidation, hydrolysis, photolysis, and heat. The method was validated for specificity, selectivity, linearity, precision, accuracy, and robustness. The applied procedure was found to be linear in diltiazem concentration range of 0.5–50 μg/mL (r2 = 0.9996). Precision was evaluated by replicate analysis in which % relative standard deviation (RSD) values for areas were found below 2.0. The recoveries obtained (99.25%–101.66%) ensured the accuracy of the developed method. The degradation products as well as the pharmaceutical excipients were well resolved from the pure drug. The expanded uncertainty (5.63%) of the method was also estimated from method validation data. Accordingly, the proposed validated and sustainable procedure was proved to be suitable for routine analyzing and stability studies of diltiazem in pharmaceutical preparations. PMID:24163778

  13. Validation and uncertainty estimation of an ecofriendly and stability-indicating HPLC method for determination of diltiazem in pharmaceutical preparations.

    PubMed

    Sadeghi, Fahimeh; Navidpour, Latifeh; Bayat, Sima; Afshar, Minoo

    2013-01-01

    A green, simple, and stability-indicating RP-HPLC method was developed for the determination of diltiazem in topical preparations. The separation was based on a C18 analytical column using a mobile phase consisted of ethanol: phosphoric acid solution (pH = 2.5) (35 : 65, v/v). Column temperature was set at 50°C and quantitation was achieved with UV detection at 240 nm. In forced degradation studies, the drug was subjected to oxidation, hydrolysis, photolysis, and heat. The method was validated for specificity, selectivity, linearity, precision, accuracy, and robustness. The applied procedure was found to be linear in diltiazem concentration range of 0.5-50  μ g/mL (r (2) = 0.9996). Precision was evaluated by replicate analysis in which % relative standard deviation (RSD) values for areas were found below 2.0. The recoveries obtained (99.25%-101.66%) ensured the accuracy of the developed method. The degradation products as well as the pharmaceutical excipients were well resolved from the pure drug. The expanded uncertainty (5.63%) of the method was also estimated from method validation data. Accordingly, the proposed validated and sustainable procedure was proved to be suitable for routine analyzing and stability studies of diltiazem in pharmaceutical preparations. PMID:24163778

  14. Stability indicators in network reconstruction.

    PubMed

    Filosi, Michele; Visintainer, Roberto; Riccadonna, Samantha; Jurman, Giuseppe; Furlanello, Cesare

    2014-01-01

    The number of available algorithms to infer a biological network from a dataset of high-throughput measurements is overwhelming and keeps growing. However, evaluating their performance is unfeasible unless a 'gold standard' is available to measure how close the reconstructed network is to the ground truth. One measure of this is the stability of these predictions to data resampling approaches. We introduce NetSI, a family of Network Stability Indicators, to assess quantitatively the stability of a reconstructed network in terms of inference variability due to data subsampling. In order to evaluate network stability, the main NetSI methods use a global/local network metric in combination with a resampling (bootstrap or cross-validation) procedure. In addition, we provide two normalized variability scores over data resampling to measure edge weight stability and node degree stability, and then introduce a stability ranking for edges and nodes. A complete implementation of the NetSI indicators, including the Hamming-Ipsen-Mikhailov (HIM) network distance adopted in this paper is available with the R package nettools. We demonstrate the use of the NetSI family by measuring network stability on four datasets against alternative network reconstruction methods. First, the effect of sample size on stability of inferred networks is studied in a gold standard framework on yeast-like data from the Gene Net Weaver simulator. We also consider the impact of varying modularity on a set of structurally different networks (50 nodes, from 2 to 10 modules), and then of complex feature covariance structure, showing the different behaviours of standard reconstruction methods based on Pearson correlation, Maximum Information Coefficient (MIC) and False Discovery Rate (FDR) strategy. Finally, we demonstrate a strong combined effect of different reconstruction methods and phenotype subgroups on a hepatocellular carcinoma miRNA microarray dataset (240 subjects), and we validate the

  15. Isolation, Characterization, Crystal Structure Elucidation of Two Flavanones and Simultaneous RP-HPLC Determination of Five Major Compounds from Syzygium campanulatum Korth.

    PubMed

    Memon, Abdul Hakeem; Ismail, Zhari; Al-Suede, Fouad Saleih Resq; Aisha, Abdalrahim F A; Hamil, Mohammad Shahrul Ridzuan; Saeed, Mohammed Ali Ahmed; Laghari, Madeeha; Majid, Amin Malik Shah Abdul

    2015-01-01

    Two flavanones named (2S)-7-Hydroxy-5-methoxy-6,8-dimethyl flavanone (1), (S)-5,7-dihydroxy-6,8-dimethyl-flavanone (2), along with known chalcone, namely, (E)-2',4'- dihydroxy-6'-methoxy-3',5'-dimethylchalcone (3) and two triterpenoids, namely, betulinic and ursolic acids (4 and 5), were isolated from the leaves of Syzygium campanulatum Korth (Myrtaceae). The structures of compounds (1 and 2) were determined on the basis of UV-visible, FTIR, NMR spectroscopies and LC-EIMS analytical techniques. Furthermore, new, simple, precise, selective, accurate, highly sensitive, efficient and reproducible RP-HPLC method was developed and validated for the quantitative analysis of the compounds (1-5) from S. campanulatum plants of five different age. RP-HPLC method was validated in terms of specificity, linearity (r2 ≤ 0.999), precision (2.0% RSD), and recoveries (94.4%-105%). The LOD and LOQ of these compounds ranged from 0.13-0.38 and 0.10-2.23 μg·mL-1, OPEN ACCESS respectively. Anti-proliferative activity of isolated flavanones (1 and 2) and standardized extract of S. campanulatum was evaluated on human colon cancer (HCT 116) cell line. Compounds (1 and 2) and extract revealed potent and dose-dependent activity with IC50 67.6, 132.9 and 93.4 μg·mL-1, respectively. To the best of our knowledge, this is the first study on isolation, characterization, X-ray crystallographic analysis of compounds (1 and 2) and simultaneous RP-HPLC determination of five major compounds (1-5) from different age of S. campanulatum plants. PMID:26248073

  16. Isolation, Characterization, and RP-HPLC Estimation of P-Coumaric Acid from Methanolic Extract of Durva Grass (Cynodon dactylon Linn.) (Pers.)

    PubMed Central

    Karthikeyan, Ramadoss; Devadasu, Chapala; Srinivasa Babu, Puttagunta

    2015-01-01

    P-coumaric acid is a nonflavonoid phenolic acid and is a major constituent of the species Cynodon dactylon Linn. (Pers.). In this study isolation of P-coumaric acid was achieved by preparative TLC and the compound thus isolated was characterised by UV, mass, and H1 NMR spectral analysis. An isocratic RP-HPLC method was developed for the estimation of P-coumaric acid from methanolic extracts of durva grass. The chromatographic separations were achieved by RP-C18 column (250 mm × 4.6 mm, 5 μ), Shimadzu LC-20AT Prominence liquid chromatograph, and a mobile phase composed of water : methanol : glacial acetic acid (65 : 34 : 1 v/v). The flow rate was 1.0 mL/min and the analyses of column effluents were performed using UV-visible detector at 310 nm. Retention time of P-coumaric acid was found to be 6.617 min. This method has obeyed linearity over the concentration range of 2–10 μg/mL and the regression coefficient obtained from linearity plot for P-coumaric acid was found to be 0.999. RP-HPLC method was validated in pursuance of ICH guidelines. PMID:25788944

  17. Validation of a RP-HPLC-DAD Method for Chamomile (Matricaria recutita) Preparations and Assessment of the Marker, Apigenin-7-glucoside, Safety and Anti-Inflammatory Effect

    PubMed Central

    Miguel, Felipe Galeti; Cavalheiro, Amanda Henriques; Spinola, Nathália Favaretto; Ribeiro, Diego Luis; Barcelos, Gustavo Rafael Mazzaron; Antunes, Lusânia Maria Greggi; Hori, Juliana Issa; Marquele-Oliveira, Franciane; Rocha, Bruno Alves; Berretta, Andresa Aparecida

    2015-01-01

    Chamomile is a medicinal plant, which presents several biological effects, especially the anti-inflammatory effect. One of the compounds related to this effect is apigenin, a flavonoid that is mostly found in its glycosylated form, apigenin-7-glucoside (APG), in natural sources. However, the affectivity and safety of this glycoside have not been well explored for topical application. In this context, the aim of this work was to develop and validate a reversed-phase high-performance liquid chromatography (RP-HPLC-DAD) method to quantify APG in chamomile preparations. Additionally, the safety and the anti-inflammatory potential of this flavonoid were verified. The RP-HPLC-DAD method was developed and validated with linearity at 24.0–36.0 μg/mL range (r = 0.9994). Intra- and interday precision (RSD) were 0.27–2.66% and accuracy was 98.27–101.21%. The validated method was applied in the analysis of chamomile flower heads, glycolic extract, and Kamillen cream, supporting the method application in the quality control of chamomile preparations. Furthermore, the APG safety was assessed by MTT cytotoxicity assay and mutagenic protocols and the anti-inflammatory activity was confirmed by a diminished TNF-α production showed by mice macrophages treated with APG following LPS treatment. PMID:26421053

  18. Validation of a RP-HPLC-DAD Method for Chamomile (Matricaria recutita) Preparations and Assessment of the Marker, Apigenin-7-glucoside, Safety and Anti-Inflammatory Effect.

    PubMed

    Miguel, Felipe Galeti; Cavalheiro, Amanda Henriques; Spinola, Nathália Favaretto; Ribeiro, Diego Luis; Barcelos, Gustavo Rafael Mazzaron; Antunes, Lusânia Maria Greggi; Hori, Juliana Issa; Marquele-Oliveira, Franciane; Rocha, Bruno Alves; Berretta, Andresa Aparecida

    2015-01-01

    Chamomile is a medicinal plant, which presents several biological effects, especially the anti-inflammatory effect. One of the compounds related to this effect is apigenin, a flavonoid that is mostly found in its glycosylated form, apigenin-7-glucoside (APG), in natural sources. However, the affectivity and safety of this glycoside have not been well explored for topical application. In this context, the aim of this work was to develop and validate a reversed-phase high-performance liquid chromatography (RP-HPLC-DAD) method to quantify APG in chamomile preparations. Additionally, the safety and the anti-inflammatory potential of this flavonoid were verified. The RP-HPLC-DAD method was developed and validated with linearity at 24.0-36.0 μg/mL range (r = 0.9994). Intra- and interday precision (RSD) were 0.27-2.66% and accuracy was 98.27-101.21%. The validated method was applied in the analysis of chamomile flower heads, glycolic extract, and Kamillen cream, supporting the method application in the quality control of chamomile preparations. Furthermore, the APG safety was assessed by MTT cytotoxicity assay and mutagenic protocols and the anti-inflammatory activity was confirmed by a diminished TNF-α production showed by mice macrophages treated with APG following LPS treatment. PMID:26421053

  19. Two-dimensional separation of peptides using RP-RP-HPLC system with different pH in first and second separation dimensions.

    PubMed

    Gilar, Martin; Olivova, Petra; Daly, Amy E; Gebler, John C

    2005-09-01

    Two-dimensional high performance liquid chromatography is a useful tool for proteome analysis, providing a greater peak capacity than single-dimensional LC. The most popular 2D-HPLC approach used today for proteomic research combines strong cation exchange and reversed-phase HPLC. We have evaluated an alternative mode for 2D-HPLC of peptides, employing reversed-phase columns in both separation dimensions. The orthogonality of 2D separation was investigated for selected types of RP stationary phases, ion-pairing agents and mobile phase pH. The pH appears to have the most significant impact on the RP-LC separation selectivity; the greatest orthogonality was achieved for the system with C18 columns using pH 10 in the first and pH 2.6 in the second LC dimension. Separation was performed in off-line mode with partial fraction evaporation. The achievable peak capacity in RP-RP-HPLC and overall performance compares favorably to SCX-RP-HPLC and holds promise for proteomic analysis. PMID:16224963

  20. RP-HPLC-DAD analysis of phenolic compounds in pomace extracts from five grape cultivars: Evaluation of their antioxidant, antiradical and antifungal activities in orange and apple juices.

    PubMed

    Sagdic, Osman; Ozturk, Ismet; Ozkan, Gulcan; Yetim, Hasan; Ekici, Lutfiye; Yilmaz, Mustafa Tahsin

    2011-06-15

    Phenolic compounds, related to antioxidative and antifungal properties of ethanolic extracts from five commercial grape cultivars (three red and two white) grown in Turkey were determined. A reversed-phase high performance liquid chromatography (RP-HPLC) procedure was developed, and a total 18 different phenolic compounds were identified. Total phenolic contents of the extracts were determined using Folin-Ciocalteau method. Antioxidant activities of the extracts were evaluated by using DPPH radical scavenging and phosphomolybdenum methods. All extracts exhibited strong antioxidant and antiradical activity. Phenolic compounds and antioxidant activities of the extracts were variety dependent. Antifungal activities of the pomaces and extracts were screened by both in vitro agar-well diffusion assay and antifungal activity in apple and orange juices in situ using Zygosaccharomyces rouxii and Z. bailii. Antifungal activities revealed that the pomaces and extracts of Gamay and Kalecik karasi could be more effective antifungal agents than those of Emir, Narince and Okuzgozu grape cultivars. PMID:25213954

  1. A simple method for simultaneous RP-HPLC determination of indolic compounds related to bacterial biosynthesis of indole-3-acetic acid.

    PubMed

    Szkop, Michał; Bielawski, Wiesław

    2013-03-01

    In this short technical report, we present a fast and simple procedure for sample preparation and a single-run Reversed Phase High Performance Liquid Chromatography (RP-HPLC) determination of seven indoles (indole-3-acetic acid, indole-3-acetamide, indole-3-acetonitrile, indole-3-ethanol, indole-3-lactic acid, tryptamine and tryptophan) in bacterial culture supernatants. The separation of the analytes, after a single centrifugal filtration clean-up step, was performed using a gradient elution on a symmetry C8 column followed by fluorimetric detection (λ(ex) = 280/λ(em) = 350 nm). The calibration curves were linear for all of the studied compounds over the concentration range of 0.0625-125 μg mL(-1) (r ( 2 ) ≥ 0.998) and the limits of detection were below 0.015 μg mL(-1). The applicability of the method was confirmed by analysis of Pseudomonas putida culture supernatants. PMID:23111785

  2. Tocochromanols composition in kernels recovered from different apricot varieties: RP-HPLC/FLD and RP-UPLC-ESI/MS(n) study.

    PubMed

    Górnaś, Paweł; Mišina, Inga; Grāvīte, Ilze; Soliven, Arianne; Kaufmane, Edīte; Segliņa, Dalija

    2015-01-01

    Composition of tocochromanols in kernels recovered from 16 different apricot varieties (Prunus armeniaca L.) was studied. Three tocopherol (T) homologues, namely α, γ and δ, were quantified in all tested samples by an RP-HPLC/FLD method. The γ-T was the main tocopherol homologue identified in apricot kernels and constituted approximately 93% of total detected tocopherols. The RP-UPLC-ESI/MS(n) method detected trace amounts of two tocotrienol homologues α and γ in the apricot kernels. The concentration of individual tocopherol homologues in kernels of different apricots varieties, expressed in mg/100 g dwb, was in the following range: 1.38-4.41 (α-T), 42.48-73.27 (γ-T) and 0.77-2.09 (δ-T). Moreover, the ratio between individual tocopherol homologues α:γ:δ was nearly constant in all varieties and amounted to approximately 2:39:1. PMID:25567675

  3. Comparative studies on performance of CCC and preparative RP-HPLC in separation and purification of steroid saponins from Dioscorea zingiberensis C.H.Wright

    PubMed Central

    Zhang, Xinxin; Liang, Jinru; Zhang, Yongmin; Liu, Jianli; Sun, Wenji; Ito, Yoichiro

    2015-01-01

    Steroid saponins from Dioscorea zingiberensis C.H.Wright were separated for the first time using two chromatographic methods for comparison: counter-current chromatography (CCC) coupled with evaporative light scattering detector (ELSD) and preparative reversed phase high-performance liquid chromatography (RP-HPLC) with an ultraviolet detector. Ethyl acetate-n-butanol-methanol-water (4:1:2:4, v/v) was chosen as the two-phase solvent system for CCC, while the acetonitrile-water (25:75 for the first step and15:85 for the second step, v/v) was used as the mobile phase in the preparative RP-HPLC. The following five steroid saponins were purified by theses two chromatographic methods, in one-step operation by CCC and by two-step operation in preparative RP-HPLC: 1) 26-O-β-D- glucopyranosyl-(25R)-furost-5-en-3β, 22ζ, 26-triol-3-O-[β-D-glucopyranosyl-(1→3)-β-D-glucopyranosyl-(1→4)-α-L-rhamnopyranosyl-(1→2)]-β-D-glucopyranoside (compound A), 2) 26-O-β-D-glucopyranosyl-(25R)-furost-5-en-3β, 22ζ, 4) 26-triol-3-O-[β-D-glucopyranosyl-(1→3)-α-L-rhamnopyranosyl-(1→2)]-β-D-glucopyranoside (compound B), 3) 26-O-β-D-glucopyranosyl-(25R)-furost-5-en-3β, 22ζ, 26-triol-3-O-[α-L-rhamnopyranosyl-(1→4)]-β-D-glucopyranoside (compound C), 4) 26-O-β-D-glucopyranosyl-(25R)-furost-5, 20(22)-diene-3β, 26-diol-3-O-{α-L-rhamnopyranosyl-(1→4)-[β-D-glucopyranosyl-(1→3)-β-D-glucopyranosyl-(1→2)]}-β-D-glucopyranoside (compound D) and 5) 26-O-β-D-glucopyranosyl-(25R)-furost-5, 20(22)-diene-3β, 26-diol-3-O-[β-D-glucopyranosyl-(1→4)-α-L-rhamnopyranosy-(1→2)]-β-D-glucopyranoside (compound E). The purities of these five steroid saponins separated by both methods were over 95%, and structural identification of these compounds was performed by ESI-MS, and 13C NMR. Comparison of these two established approaches revealed that CCC required a longer separation time but with less solvent consumption, whereas preparative RP-HPLC gave a shorter separation time but

  4. Dual Wavelength RP-HPLC Method for Simultaneous Determination of Two Antispasmodic Drugs: An Application in Pharmaceutical and Human Serum

    PubMed Central

    Hasan, Najmul; Chaiharn, Mathurot; Khan, Sauleha; Khalid, Hira; Sher, Nawab; Siddiqui, Farhan Ahmed; Siddiqui, Muhammad Zain

    2013-01-01

    A reverse phase stability indicating HPLC method for simultaneous determination of two antispasmodic drugs in pharmaceutical parenteral dosage forms (injectable) and in serum has been developed and validated. Mobile phase ingredients consist of Acetonitrile : buffer : sulfuric acid 0.1 M (50 : 50 : 0.3 v/v/v), at flow rate 1.0 mL/min using a Hibar μBondapak ODS C18 column monitored at dual wavelength of 266 nm and 205 nm for phloroglucinol and trimethylphloroglucinol, respectively. The drugs were subjected to stress conditions of hydrolysis (oxidation, base, acid, and thermal degradation). Oxidation degraded the molecule drastically while there was not so much significant effect of other stress conditions. The calibration curve was linear with a correlation coefficient of 0.9999 and 0.9992 for PG and TMP, respectively. The drug recoveries fall in the range of 98.56% and 101.24% with 10 pg/mL and 33 pg/mL limit of detection and limit of quantification for both phloroglucinol and trimethylphloroglucinol. The method was validated in accordance with ICH guidelines and was applied successfully to quantify the amount of trimethylphloroglucinol and phloroglucinol in bulk, injectable form and physiological fluid. Forced degradation studies proved the stability indicating abilities of the method. PMID:24286017

  5. Dual Wavelength RP-HPLC Method for Simultaneous Determination of Two Antispasmodic Drugs: An Application in Pharmaceutical and Human Serum.

    PubMed

    Hasan, Najmul; Chaiharn, Mathurot; Khan, Sauleha; Khalid, Hira; Sher, Nawab; Siddiqui, Farhan Ahmed; Siddiqui, Muhammad Zain

    2013-01-01

    A reverse phase stability indicating HPLC method for simultaneous determination of two antispasmodic drugs in pharmaceutical parenteral dosage forms (injectable) and in serum has been developed and validated. Mobile phase ingredients consist of Acetonitrile : buffer : sulfuric acid 0.1 M (50 : 50 : 0.3 v/v/v), at flow rate 1.0 mL/min using a Hibar μ Bondapak ODS C18 column monitored at dual wavelength of 266 nm and 205 nm for phloroglucinol and trimethylphloroglucinol, respectively. The drugs were subjected to stress conditions of hydrolysis (oxidation, base, acid, and thermal degradation). Oxidation degraded the molecule drastically while there was not so much significant effect of other stress conditions. The calibration curve was linear with a correlation coefficient of 0.9999 and 0.9992 for PG and TMP, respectively. The drug recoveries fall in the range of 98.56% and 101.24% with 10 pg/mL and 33 pg/mL limit of detection and limit of quantification for both phloroglucinol and trimethylphloroglucinol. The method was validated in accordance with ICH guidelines and was applied successfully to quantify the amount of trimethylphloroglucinol and phloroglucinol in bulk, injectable form and physiological fluid. Forced degradation studies proved the stability indicating abilities of the method. PMID:24286017

  6. Stability-Indicating HPLC Method for the Simultaneous Determination of HIV Tablet Containing Emtricitabine, Tenofovir Disoproxil Fumarate, and Rilpivirine Hydrochloride in Pharmaceutical Dosage Forms

    PubMed Central

    Venkatesan, S.; Kannappan, N.; Mannemala, Sai Sandeep

    2014-01-01

    A simple, accurate, rapid, and stability-indicating RP-HPLC method for a combination of tenofovir disoproxil fumarate, emtricitabine, and rilpivirine has been developed and subsequently validated in commercial tablets. The proposed HPLC method utilizes Phenomenex Gemini C18 column (150 mm × 4.6 mm i.d., 5 µm) and mobile phase consisting of MeCN, potassium dihydrogen phosphate buffer (20 mM, pH 3.3), and triethylamine 58.72 : 41.23 : 0.05 (v/v) at a flow rate of 1.7 mL/min. Quantitation was achieved with UV detection at 270 nm. The method was validated in terms of accuracy, precision, linearity, limits of detection, limits of quantitation, and robustness. This optimized method has been successively applied to pharmaceutical formulation and no interference from the tablet excipients was found. TDF, EMT, and RPV and their combination drug product were subjected to acid, base, neutral hydrolysis, oxidation, dry heat, and photolytic stress conditions and the stressed samples were analyzed by the proposed method. As the proposed LC method could effectively separate the drugs from its degradation products, it can be employed as stability-indicating method for the determination of instability of these drugs in bulk and commercial tablets.

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

    PubMed Central

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

    2013-01-01

    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 μm 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 μg/mL of propranolol and the concentration range 4-32 μg/mL of valsartan. Limit of detection and limit of quantitation for propranolol were 0.27 μg/mL and 0.85 μg/mL, and for valsartan were 0.45 μg/mL and 1.39 μg/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

  8. [Simultaneous separation and detection of principal component isomer and related substances of raw material drug of ammonium glycyrrhizinate by RP-HPLC and structure confirmation].

    PubMed

    Zhao, Yan-Yan; Liu, Li-Yan; Han, Yuan-Yuan; Li, Yue-Qiu; Wang, Yan; Shi, Min-Jian

    2013-08-01

    A simple, fast and sensitive analytical method for the simultaneous separation and detection of 18alpha-glycyrrhizinic acid, 18beta-glycyrrhizinic acid, related substance A and related substance B by RP-HPLC and drug quality standard was established. The structures of principal component isomer and related substances of raw material drug of ammonium glycyrrhizinate have been confirmed. Reference European Pharmacopoeia EP7.0 version, British Pharmacopoeia 2012 version, National Drug Standards of China (WS 1-XG-2002), domestic and international interrelated literature were referred to select the composition of mobile phase. The experimental parameters including salt concentration, pH, addition quantities of organic solvent, column temperature and flow rate were optimized. Finally, the assay was conducted on a Durashell-C18 column (250 mm x 4.6 mm, 5 microm) with 0.01 mol x mL(-1) ammonium perchlorate (add ammonia to adjust the pH value to 8.2) -methanol (48 : 52) as mobile phase at the flow rate of 0.8 mL x min(-1), and the detection wavelength was set at 254 nm. The column temperature was 50 degrees C and the injection volume was 10 microL. The MS, NMR, UV and RP-HPLC were used to confirm the structures of principal component isomer and related substances of raw material drug of ammonium glycyrrhizinate. Under the optimized separation conditions, the calibration curves of 18 alpha-glycyrrhizinic acid, 18beta-glycyrrhizinic acid, related substance A and related substance B showed good linearity within the concentration of 0.50-100 microg x mL(-1) (r = 0.999 9). The detection limits for 18alpha-glycyrrhizinic acid, 18beta-glycyrrhizinic acid, related substance A and related substance B were 0.15, 0.10, 0.10, 0.15 microg x mL(-1) respectively. The method is sensitive, reproducible and the results are accurate and reliable. It can be used for chiral resolution of 18alpha-glycyrrhizinic acid, 18Pbeta-glycyrrhizinic acid, and detection content of principal component and

  9. Antioxidant, Biomolecule Oxidation Protective Activities of Nardostachys jatamansi DC and Its Phytochemical Analysis by RP-HPLC and GC-MS

    PubMed Central

    Razack, Sakina; Hemanth Kumar, Kandikattu; Nallamuthu, Ilaiyaraja; Naika, Mahadeva; Khanum, Farhath

    2015-01-01

    The study aimed at analyzing the metabolite profile of Nardostachys jatamansi using RP-HPLC, GC-MS and also its antioxidant, biomolecule protective and cytoprotective properties. The 70% ethanolic extract of Nardostachys jatamansi (NJE) showed the presence of polyphenols and flavonoids (gallic acid, catechin, chlorogenic acid, homovanillin, epicatechin, rutin hydrate and quercetin-3-rhamnoside) analyzed by RP-HPLC, whereas hexane extract revealed an array of metabolites (fatty acids, sesquiterpenes, alkane hydrocarbons and esters) by GC-MS analysis. The antioxidant assays showed the enhanced potency of NJE with a half maximal inhibitory concentration (IC50) value of 222.22 ± 7.4 μg/mL for 2,2-diphenyl-1-picrylhydrazyl (DPPH), 13.90 ± 0.5 μg/mL for 2,2′-azino-bis(3-ethyl benzothiazoline-6-sulfonic acid) diammonium salt (ABTS), 113.81 ± 4.2 μg/mL for superoxide, 948 ± 21.1 μg/mL for metal chelating and 12.3 ± 0.43 mg FeSO4 equivalent/g of extract for ferric reducing antioxidant power assays and was more potent than hexane extract. NJE effectively inhibited 2,2′-azobis(2-methylpropionamidine) dihydrochloride (AAPH)-induced oxidation of biomolecules analyzed by pBR322 plasmid DNA damage, protein oxidation of bovine serum albumin and lipid peroxidation assays. The observed effects might be due to the high content of polyphenols, 53.06 ± 2.2 mg gallic acid equivalents/g, and flavonoids, 25.303 ± 0.9 mg catechin equivalents/g, of NJE compared to the hexane fraction. Additionally, the extract abrogated the protein, carbonyl, and ROS formation, and NJE showed cytotoxicity in SH-SY5Y neuronal cells above 75 μg/mL. Thus, the study suggests that the herb unequivocally is a potential source of antioxidants and could aid in alleviating oxidative stress-mediated disorders. PMID:26785345

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

    PubMed

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

    2013-03-01

    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 μm 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 μg/ml & 0.05 μg/ml, whereas the limit of quantification was 0.19 μg/ml & 0.15 μg/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

  11. Development and validation of a stability-indicating RP-HPL C-CAD method for gabapentin and its related impurities in presence of degradation products.

    PubMed

    Ragham, Pramod Kumar; Chandrasekhar, Kothapalli B

    2016-06-01

    The objective of the current study was to develop and validate a sensitive and specific LC-MS compatible stability indicating reversed phase liquid chromatographic method for the quantitative determination of Gabapentin and its related substances using Corona charged aerosol detection (CAD). The chromatographic conditions were optimized using a Kinetix Biphenyl column with gradient elution using a mobile phase composed of pH 4.2 ammonium acetate, acetonitrile, and methanol. Forced degradation was observed in basic and peroxide conditions and the major degradants were identified by LC-MS/MS analysis. The developed RP-HPLC CAD method was validated according to ICH guidelines. The LOD and LOQ values for Gabapentin and all its related impurities ranged from 0.075μg/mL to 0.18μg/mL and 0.25μg/mL to 0.60μg/mL, respectively. The recovery for all impurities ranged from 91.0 to 105.6%w/w. Solutions were stable for 7days at room temperature. The validated method produced acceptable precision, linearity, accuracy, robustness and ruggedness. PMID:27018505

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

    PubMed Central

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

    2013-01-01

    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 μm 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 μg/ml & 0.05 μg/ml, whereas the limit of quantification was 0.19 μg/ml & 0.15 μg/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

  13. Simultaneous RP-HPLC-DAD quantification of bromocriptine, haloperidol and its diazepane structural analog in rat plasma with droperidol as internal standard for application to drug-interaction pharmacokinetics

    PubMed Central

    Billups, Johnique; Jones, Cynthia; Jackson, Tanise L.; Ablordeppey, Seth Y.; Spencer, Shawn D.

    2010-01-01

    A simple and rapid RP-HPLC-DAD method was developed and validated for simultaneous determination of the dopamine antagonists haloperidol, its diazepane analog, and the dopamine agonist bromocriptine in rat plasma, to perform pharmacokinetic drug-interaction studies. Samples were prepared for analysis by acetonitrile (22.0 μg/mL) plasma protein precipitation with droperidol as an internal standard, followed by a double-step liquid-liquid extraction with hexane:chloroform (70:30) prior to C-18 separation. Isocratic elution was achieved using a 0.1% (v/v) trifluoroacetic acid in deionized water, methanol and acetonitrile (45/27.5/27.5, v/v/v). Triple-wavelength diode-array detection at the λmax of 245 nm for haloperidol, 254 nm for the diazepane analog and droperidol, and 240 nm for bromocriptine was carried out. The LLOQ of DAL, HAL, and BCT were 45.0, 56.1, and 150 ng/mL, respectively. In rats, the estimated pharmacokinetic parameters (i.e., t1/2, CL, and Vss) of HAL when administered with DAL and BCT were t1/2 = 16.4 min, Vss = 0.541 L/kg for HAL, t1/2 = 28.0 min, Vss = 2.00 L/kg for DAL, and t1/2 = 24.0 min, Vss = 0.106 L/kg for BCT. The PK parameters for HAL differed significantly from those previously reported, which may be an indication of a drug-drug interaction. PMID:19908205

  14. Development and Validation of Simple RP-HPLC Method for Intracellular Determination of Fluconazole Concentration and Its Application to the Study of Candida albicans Azole Resistance

    PubMed Central

    Davtyan, Tigran K.; Melikyan, Levon A.; Nikoyan, Nune A.; Aleksanyan, Hripsime P.; Grigoryan, Nairi G.

    2015-01-01

    Candida albicans (strains NCTC-885-653 and ATCC-10231) long-term cultivated in the presence of antifungal agent fluconazole (FLC) and classical microbiological methods for determination of minimal inhibitory concentration (MIC) were used in this study. A simple and sensitive method based on reverse-phase high-performance liquid chromatography (RP-HPLC) has been developed for the determination of FLC intracellular concentration in C. albicans using tinidazole as an internal standard. Following extraction with dichloromethane, the chromatographic separation was achieved on a Machery-Nagel EC250/2 Nucleodur-100-3 C18 column by gradient elution using the mobile phase consisting of (A) 0.01 M ammonium acetate buffer, pH = 5.00, and (B) acetonitrile. Different analytical performance parameters such as linearity, precision, accuracy, limit of quantification (LOQ), and robustness were determined according to US DHHS FDA and EMEA guidelines. The method was linear for FLC (r = 0.9999) ranging from 100 to 10000 ng/mL. The intraday and interday precisions (relative standard deviation) were within 2.79 and 2.64%, respectively, and the accuracy (relative error) was less than 2.82%. The extraction recovery ranged from 79.3 to 85.5%. The reliable method was successfully applied to C. albicans azole-resistance study and it was shown that intracellular concentration of FLC correlated with a yeast drug susceptibility profile and MIC values. PMID:26783393

  15. Simultaneous determination of multi drug components Theophylline, Etofylline, Guaiphenesine and Ambroxol Hydrochloride by validated RP-HPLC method in liquid dosage form.

    PubMed

    Jain, Jainendra Kumar; Prakash, M S; Mishra, Rajnish K; Khandhar, Amit P

    2008-04-01

    The RP-HPLC (reverse phase high performance liquid chromatography) method was developed and validated for simultaneous determination of Multi drug components i.e., Theophylline, Etofylline, Guaiphenesine and Ambroxol Hydrochloride in a liquid dosage form. Chromatographic separation of the four drugs was performed on a Hypersil Phenyl BDS (25cmX4.6mm, 5mm). The mobile phase constituted of triethylamine pH 3.0 buffer: methanol (85:15) v/v was delivered at the flow rate 1.5 mL/min. Detection was performed at 235 nm. The peak purity of Theophylline, Etofylline, Guaiphenesine and Ambroxol Hydrochloride were 0.99970, 0.99979, 0.99986 and 0.99949 respectively. Calibration curves were linear with correlation coefficient between 0.99995 to 0.99997 over a concentration range of 5 to 37 microg/mL for Theophylline, 19 to 140 microg/mL for Etofylline, 20 to 149 microg/mL for Guaiphenesine and 6 to 45 microg/mL for Ambroxol hydrochloride. The relative standard deviation (RSD) was found < 2.0%. The percentage recovery was found between the range of 98.6% and 100.5% at three different levels. Robustness and ruggedness were performed and result found within the RSD of 2%. All the parameters of validation were found in the acceptance range of ICH guideline. PMID:18390446

  16. The salivary proteome profile in patients affected by SAPHO syndrome characterized by a top-down RP-HPLC-ESI-MS platform.

    PubMed

    Sanna, Monica; Firinu, Davide; Manconi, Paolo Emilio; Pisanu, Maria; Murgia, Giuseppe; Piras, Valentina; Castagnola, Massimo; Messana, Irene; del Giacco, Stefano Renato; Cabras, Tiziana

    2015-06-01

    SAPHO syndrome is a rare and often unrecognized disease with prominent inflammatory cutaneous and articular symptoms characterized by musculoskeletal manifestations (synovitis, hyperostosis, osteomyelitis) associated with dermatological conditions (severe acne and pustulosis). The acidic soluble fraction of whole saliva from 10 adult women affected by SAPHO syndrome and from a group of 28 healthy women was analysed by RP-HPLC-ESI-MS with the aim of discovering salivary biomarkers of the disorder. The levels of the oral proteins and peptides were correlated with clinical data. The following proteins showed a significant decreased concentration in saliva of SAPHO subjects with respect to controls: cystatin S1 and SN, histatins, the major acidic PRPs, P-C and P-B peptides. The cystatin SN abundance lowered according to the disease duration and histatins showed positive correlations with the C reactive protein. Statistical analysis performed excluding one patient with a different pattern of salivary proteins/peptides highlighted a positive relationship between cystatin S1, histatins 3, histatin 5, and the neutrophil count. Moreover, histatin 3 correlated positively with the total white cell count and negatively with the erythrocyte sedimentation rate. Levels and frequency of S100A12 protein showed a trend to increase in SAPHO patients. The high expression of this pro-inflammatory protein is probably related to the inflammatory response and to the altered neutrophil responses to functional stimuli that characterize SAPHO syndrome suggesting a possible application as a salivary biomarker. PMID:25671558

  17. Separation and quantitative determination of cinacalcet metabolites in urine sample using RP-HPLC after derivation with a fluorescent labeling reagent.

    PubMed

    Farnoudian-Habibi, Amir; Jaymand, Mehdi

    2016-08-01

    In this investigation, a novel strategy for separation and quantitative determination of four metabolites of cinacalcet (M2a-Glu, M2b-Glu, M7-Gly, and M8-Gly) in human urine is suggested. The analytical assay is based on a pre-column derivation procedure of cinacalcet metabolites with 1-pyrenyldiazomethane (PDAM) as a fluorescent labeling reagent, and subsequently separation and quantitative determination with reverse-phase high-performance liquid chromatography (RP-HPLC) coupled with a fluorescence detector. Metabolites were separated on a Microsorb-MV 100-5 C18 chromatography column (250×4.6mm, 5μm) using acetate buffer (pH 3.5):methanol (30:70 v/v) as mobile phase at a flow rate of 1.0mLmin(-1). The method was fully validated in terms of linearity (r(2)>0.996; 1-10ngmL(-1)), precision (both intra-day and inter-day; RSD<6.2%), accuracy (92-110%), specificity, robustness (0.15%

  18. Simultaneous and rapid determination of the anticarcinogenic proteins Bowman-Birk inhibitor and lectin in soybean crops by perfusion RP-HPLC.

    PubMed

    Anta, Lucía; Luisa Marina, M; García, M Concepción

    2010-11-01

    There are numerous studies demonstrating a direct association between the ingestion of soybean and low cancer incidence. This fact has been related to the presence of Bowman-Birk inhibitor (BBI) and lectin in soybean. The simultaneous and fast determination of BBI and lectin in soybean is proposed, for the first time, in this work. Two different strategies were designed for the extraction of BBI and lectin: extraction of soybean proteins using a Tris-HCl buffer followed by isolation of BBI and lectin by the isoelectric precipitation of other soybean proteins (method I) or by the direct extraction of BBI and lectin using an acetate buffer (method II). The effect of the previous soybean defating on the extraction of BBI and lectin was also studied. Moreover, the possibility of using a high-intensity focalized ultrasonic probe for accelerating the extraction was explored and an optimization of the extraction time and ultrasound amplitude was performed. The extracts obtained were analysed by RP-HPLC-ESI-MS for the correct identification of BBI and lectin in soybean. Moreover, a fast chromatographic methodology using a perfusion column and UV detection was optimized for the rapid determination of BBI and lectin in soybean. After evaluating its analytical characteristics (linearity, precision, and recovery), the method was applied to the quantitation of BBI and lectin in different soybean varieties. PMID:20889157

  19. Analytical Eco-Scale for Assessing the Greenness of a Developed RP-HPLC Method Used for Simultaneous Analysis of Combined Antihypertensive Medications.

    PubMed

    Mohamed, Heba M; Lamie, Nesrine T

    2016-09-01

    In the past few decades the analytical community has been focused on eliminating or reducing the usage of hazardous chemicals and solvents, in different analytical methodologies, that have been ascertained to be extremely dangerous to human health and environment. In this context, environmentally friendly, green, or clean practices have been implemented in different research areas. This study presents a greener alternative of conventional RP-HPLC methods for the simultaneous determination and quantitative analysis of a pharmaceutical ternary mixture composed of telmisartan, hydrochlorothiazide, and amlodipine besylate, using an ecofriendly mobile phase and short run time with the least amount of waste production. This solvent-replacement approach was feasible without compromising method performance criteria, such as separation efficiency, peak symmetry, and chromatographic retention. The greenness profile of the proposed method was assessed and compared with reported conventional methods using the analytical Eco-Scale as an assessment tool. The proposed method was found to be greener in terms of usage of hazardous chemicals and solvents, energy consumption, and production of waste. The proposed method can be safely used for the routine analysis of the studied pharmaceutical ternary mixture with a minimal detrimental impact on human health and the environment. PMID:27492952

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

    PubMed

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

    2015-04-01

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

  1. Determination of free and bound phenolic compounds in buckwheat spaghetti by RP-HPLC-ESI-TOF-MS: effect of thermal processing from farm to fork.

    PubMed

    Verardo, Vito; Arraez-Roman, David; Segura-Carretero, Antonio; Marconi, Emanuele; Fernandez-Gutierrez, Alberto; Caboni, Maria Fiorenza

    2011-07-27

    Nowadays there is considerable interest in the consumption of alternative crops as potential recipes for gluten-free products production. Therefore, the use of buckwheat for the production of gluten-free pasta has been investigated in the present study. RP-HPLC-ESI-TOF-MS has been applied for the separation and characterization of free and bound phenolic compounds in buckwheat flour and buckwheat spaghetti. Thus, 32 free and 24 bound phenolic compounds in buckwheat flour and spaghetti have been characterized and quantified. To the authors' knowledge, protochatechuic-4-O-glucoside acid and procyanidin A have been detected in buckwheat for the first time. The results have demonstrated a decrease of total free phenolic compounds from farm to fork (from flour to cooked spaghetti) of about 74.5%, with a range between 55.3 and 100%, for individual compounds. The decrease in bound phenols was 80.9%, with a range between 46.2 and 100%. The spaghetti-making process and the cooking caused losses of 46.1 and 49.4% of total phenolic compounds, respectively. Of the total phenolic compounds present in dried spaghetti, 11.6% were dissolved in water after cooking. PMID:21678994

  2. Simultaneous determination of cefazolin or ceftizoxime in presence of ascorbic acid from pharmaceutical formulation and human serum by RP-HPLC.

    PubMed

    Arayne, M Saeed; Sultana, Najma; Bi Bi, Zakia

    2007-01-01

    A rapid, sensitive and specific RP-HPLC method involving HPLC-UV detection was developed and validated for simultaneous determination and quantification of cefazoline or ceftizoxime in presence of ascorbic acid. Chromatography was carried out on a pre-packed Kromasil 100, C(18) (5 microm 25 x 0.46 cm) column using acetonitrile: water (60:40; v/v) as mobile phase at a flow rate of 0.75 ml/minute and effluent were monitored at 265 nm for cefazoline and ascorbic acid while at 270 nm for ceftizoxime. The assay was linear over the concentration range of 0.05-100 microg/ml. The method is convenient for determination of cefazoline or ceftizoxime in presence of ascorbic acid with percent recovery ranging from 99.0-100.0% with an inter and intra day CV <3%. The method does not require more than 8 minutes for analysis with good peak resolution and low LOD 0.1 microg/ml and LOQ 0.3 microg/ml. PMID:17337430

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

    PubMed

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

    2014-12-01

    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. PMID:24944096

  4. 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.

    PubMed

    Hu, Qiufen; Yang, Guangyu; Zhao, Yiyun; Yin, Jiayuan

    2003-03-01

    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 (T m-APP) to form colored chelates. The metal-T m-APP chelates in 100 mL of sample were preconcentrated to 1 mL by solid-phase extraction with a C(18 )cartridge; an enrichment factor of 100 was achieved. The chelates were separated on a Waters Xterra()RP(18) column by gradient elution with methanol (containing 0.05 mol L(-1) pyrrolidine-acetic acid buffer salt, pH 10.0) and acetone (containing 0.05 mol L(-1) pyrrolidine-acetic acid buffer salt, pH 10.0) as mobile phase at a flow rate of 1.0 mL min(-1) and detected with a photodiode array detector. The detection limits of copper, cobalt, nickel, silver, lead, cadmium, and mercury are 2, 2, 3, 4, 3, 3, and 3 ng L(-1), respectively, in the original sample. The method was also applied to the determination of these metals in water with good results. PMID:12664186

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

    PubMed Central

    Rocha, Bruno Alves; Bueno, Paula Carolina Pires; Vaz, Mirela Mara de Oliveira Lima Leite; Nascimento, Andresa Piacezzi; Ferreira, Nathália 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; Acésio, Nathália de Oliveira; Martins, Sabrina de Paula Lima; Tavares, Denise Crispim; Berretta, Andresa Aparecida

    2013-01-01

    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

  6. 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

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

    2013-03-12

    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

  7. RP-HPLC method and its validation for the determination of naloxone from a novel transdermal formulation.

    PubMed

    Panchagnula, Ramesh; Sharma, Puneet; Khandavilli, Sateesh; Varma, Manthena V S

    2004-10-01

    The aim of the present work was to develop a simple and reliable liquid chromatographic method for the quantitative determination of naloxone (NLX) in a novel transdermal formulation. Chromatography was carried out by reversed-phase technique on a C-18 column with a mobile phase composed of methanol, acetonitrile and 50 mM phosphate buffer (pH 7) in the proportion of 40:20:40 v/v/v, at a flow rate of 1 ml/min. The UV spectrophotometric determination was performed at 220 nm. This method was found to be specific and accurate with the mean recovery of 98.72% in the range of 2-50 microg/ml, and a run time of 15 min (retention time of NLX 11.3 min). Method was applied for stability testing of novel transdermal formulation developed in our laboratory. Assay content of NLX in the formulation was determined in stability samples and compared with the control samples. Statistical analysis by Student's t-test showed no significant difference between the assay content of NLX in control and test samples at 95% confidence interval. Overall, the proposed method is highly sensitive, precise and accurate and can be used for the reliable quantitation of NLX in developed transdermal formulation with the added advantage of simple procedure. PMID:15474062

  8. Simultaneous Quantitative Determination of 12 Active Components in Yuanhu Zhitong Prescription by RP-HPLC Coupled with Photodiode Array Detection

    PubMed Central

    Zhang, Xiaokai; Zhang, Song; Yang, Qian; Cao, Wei; Xie, Yanhua; Qiu, Pengcheng; Wang, Siwang

    2015-01-01

    Background: Yuanhu Zhitong prescription (YZP) is a famous traditional Chinese medicine formula, which is officially recorded in Chinese Pharmacopoeia for the treatment of stomach pain, hypochondriac pain, headache and dysmenorrhea caused by qi-stagnancy and blood stasis. It is the first report for the simultaneous determination of 12 active components in YZP. Objective: A newly, simple, accurate and reliable method for the separation and determination of 12 active components (protopine, α-allocryptopine, coptisine, xanthotol, palmatine, dehydrocorydaline, glaucine, tetrahydropalmatine, tetrahydroberberine, imperatorin, corydaline, isoimperatorin) in YZP was developed and validated using HPLC-PAD. Materials and Methods: The analytes were performed on a Phenomenex Luna-C18 (2) column (250×4.6 mm, 5.0 μm) with a gradient elution program using a mixture of acetonitrile and 0.1% phosphoric acid water solution (adjusted with triethylamine to pH 5.6) as mobile phase. Analytes were performed at 30°C with a flow rate of 1.0 mL/min. Results: The validated method was applied to analyze four major dosage forms of YZP coming from different manufacturers with good linearity (r2, 0.9981~0.9999), precision (RSD, 0.24~2.89%), repeatability (RSD, 0.15~3.34%), stability (RSD, 0.14~3.35%), recovery (91.13~110.81%) of the 12 components. Conclusion: The proposed method enables the separation and determination of 12 active components in a single run for the quality control of YZP. PMID:25709212

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

    PubMed Central

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

    2013-01-01

    Chemometrics-assisted UV spectrophotometric and RP-HPLC methods are presented for the simultaneous determination of tolperisone hydrochloride (TOL) and diclofenac sodium (DIC) from their combined pharmaceutical dosage form. Chemometric methods are based on principal component regression and partial least-square regression models. Two sets of standard mixtures, calibration sets, and validation sets were prepared. Both models were optimized to quantify each drug in the mixture using the information included in the UV absorption spectra of the appropriate solution in the range 241–290 nm with the intervals λ = 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 μg/mL for TOL and 1–10 μg/mL for DIC. The robustness of the HPLC method was tested using an experimental design approach. The developed HPLC method, and the PCR and PLS models were used to determine the amount of TOL and DIC in tablets. The data obtained from the PCR and PLS models were not significantly different from those obtained from the HPLC method at 95% confidence limit. PMID:24482768

  10. Identification and optimization of parameters for the semi-continuous production of garbage enzyme from pre-consumer organic waste by green RP-HPLC method.

    PubMed

    Arun, C; Sivashanmugam, P

    2015-10-01

    Reuse and management of organic solid waste, reduce the environmental impact on human health and increase the economic status by generating valuable products for current and novel applications. Garbage enzyme is one such product produced from fermentation of organic solid waste and it can be used as liquid fertilizer, antimicrobial agents, treatment of domestic wastewater, municipal and industrial sludge treatment, etc. The semi-continuous production of garbage enzyme in large quantity at minimal time period and at lesser cost is needed to cater for treatment of increasing quantities of industrial waste activated sludge. This necessitates a parameter for monitoring and control for the scaling up of current process on semi-continuous basis. In the present study a RP-HPLC (Reversed Phase-High Performance Liquid Chromatography) method is used for quantification of standard organic acid at optimized condition 30°C column oven temperature, pH 2.7, and 0.7 ml/min flow rate of the mobile phase (potassium dihydrogen phosphate in water) at 50mM concentration. The garbage enzyme solution collected in 15, 30, 45, 60, 75 and 90 days were used as sample to determine the concentration of organic acid. Among these, 90th day sample showed the maximum concentration of 78.14 g/l of acetic acid in garbage enzyme, whereas other organic acids concentration got decreased when compare to the 15th day sample. This result confirms that the matured garbage enzyme contains a higher concentration of acetic acid and thus it can be used as a monitoring parameter for semi-continuous production of garbage enzyme in large scale. PMID:26205805

  11. Validation of RP-HPLC method and stress degradation for the combination of metformin HCl, atorvastatin calcium and glimepiride: application to nanoparticles.

    PubMed

    Gite, Sandip; Patravale, Vandana

    2015-01-01

    A stability-indicating high-performance liquid chromatography (HPLC) procedure was developed for the determination of metformin HCl (MTH), atorvastatin calcium (AC) and glimepiride (GP) in combination and their main degradation products. The separation and quantization were achieved on a 5-µm Qualisil gold, C18 column (4.6 mm × 250 mm). The mobile phase selected was phosphate buffer (pH 2.9)-organic phase in proportion of 70:30. Organic phase consisted of methanol-acetonitrile (90:10) at a flow rate of 1 mL/min and detection of analytes was carried out at 230 nm. The method exhibited good linearity over the range of 10-60 µg/mL for MTH, 2-20 µg/mL for AC and 5-30 µg/mL for GP. Square of the correlation coefficients was found to be >0.999. Various stress degradation studies were carried out in combination as per International Conference of Harmonization (ICH) guidelines for 4 h. The recovery and precision were determined in terms of intraday and interday precisions and expressed as relative standard deviations. These were <1 and <2%, respectively. Finally, the applicability of the method was evaluated in nanoparticle analysis of MTH, AC and GP as well as in stability studies of nanoformulation. PMID:26071607

  12. Determination of hydromorphone in human plasma by a sensitive RP-HPLC-ESI-MS method and its application to a clinical pharmacokinetic study in postoperative patients after low dose intravenous administration with infusion pump.

    PubMed

    Sun, Luning; Pan, Yinbin; Ding, Li; Luo, Xuemei; Yan, Zhengyu; Liu, Cunming; Qian, Yanning; Chu, Yan

    2012-03-01

    A sensitive reverse phase high performance liquid chromatography-electrospray ionization-mass spectrometry (RP-HPLC-ESI-MS) method has been developed and validated for the determination of hydromorphone in human plasma using naloxone as the internal standard (IS). After alkalization with saturated sodium bicarbonate, the plasma samples were extracted with ethyl acetate. Chromatographic separation was performed on a C18 column with the column temperature of 50 °C and a mobile phase of 5mM ammonium acetate buffer containing 1% formic acid-methanol (88:12, v/v). Hydromorphone and the IS were detected by selected ion monitoring using the protonated molecules at m/z 286.2 for hydromorphone and m/z 328.2 for the IS. Calibration curve was linear over the range of 0.01-50 ng/mL. The lower limit of quantification was 0.01 ng/mL. The method was successfully applied to the pharmacokinetic study in postoperative patients after intravenous infusion of 1.5mg hydromorphone hydrochloride. The obtained main pharmacokinetic parameters of hydromorphone in postoperative patients were as follows: the maximum hydromorphone plasma concentration (C(max)) was (24.15 ± 12.51)ng/mL, the time to the C(max) was (10.0 ± 0.0)min, and the elimination half-life was (2.7 ± 0.8)h. PMID:22169470

  13. Unique variability of tocopherol composition in various seed oils recovered from by-products of apple industry: rapid and simple determination of all four homologues (α, β, γ and δ) by RP-HPLC/FLD.

    PubMed

    Górnaś, Paweł

    2015-04-01

    The tocochromanol profile was studied in seed oils recovered from by-products of fruit industry, five dessert and seven crab apple varieties grown in Eastern Europe (Latvia). The seed oils obtained from dessert apples were characterized by higher contents of tocopherols (191.05-379.08 mg/100g oil) when compared to seed oils recovered from crab apples (130.55-202.54 mg/100g oil). The predominant homologues of tocopherol in all the studied samples were α and β over γ and δ. However, seed oils recovered from the apple cultivars 'Antej' and 'Beforest' had a unique profile of four tocopherol homologues (α:β:γ:δ) 91.41:80.55:72.46:79.03 and 114.55:112.84:78.69:73.00 mg/100g oil, respectively. A single dilution of seed oils in 2-propanol facilitated the direct use samples in the DPPH assay as well as injection into the RP-HPLC system containing a PFP (pentafluorophenyl) column, which resulted in a rapid separation of all four tocopherol homologues with excellent repeatability and reproducibility. PMID:25442533

  14. [Indications for operative stabilization of spinal fractures].

    PubMed

    Zilch, H

    1984-01-01

    Absolute indications are seen in lesions of the spinal cord; increase of an incomplete paralysis, paralysis after free interval or after a primarily good restitution and in case of an ascending complete paralysis. The decompression depends on the actual site of compression. If there is an anterior compression not laminectomy but only the anterior approach will be successful. Relative indications are instability, especially disco-ligamentious ones. Late results with permanent instability, pseudarthrosis of the dens axis and marked angulation (40 degrees) of the vertebral body. PMID:6503539

  15. [Unilateral triangular lumbopelvic stabilization: indications and techniques].

    PubMed

    Hoffmann, M F; Dudda, M; Schildhauer, T A

    2013-11-01

    Operative fixation has become treatment of choice for unstable sacral fractures. Osteosynthesis for these fractures results in loss of reduction in up to 15%. Vertical sacral fractures involving the S1 facet joint (Isler 2 and 3) may lead to multidirectional instability. Multidirectional instability of the posterior pelvic ring and lumbopelvic junction may be stabilized and forces balanced by a so-called lumbopelvic triangular fixation. Lumbopelvic triangular fixation combines vertical fixation between the lumbar vertebral pedicle and the ilium, with horizontal fixation, as an iliosacral screw or a transiliacal plate osteosynthesis. The iliac screw is directed from the posterior superior iliac spine (PSIS) to the anterior inferior iliac spine (AIIS). Thereby, lumbopelvic fixation decreases the load to the sacrum and SI joint and transfers axial loads from the lumbar spine directly onto the ilium. Triangular lumbopelvic fixation allows early full weight bearing and therefore reduces prolonged immobilization. The placement of iliac screws may be a complex surgical procedure. Thus, the technique requires thorough surgical preparation and operative logistics. Wound-related complications may occur. Preexisting Morell-Lavalée lesions increase the risk for infection. Prominent implants cause local irritation and pain. Hardware prominence and pain are markedly reduced with screw head recession into the PSIS. PMID:24233083

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

    PubMed

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

    2012-07-01

    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 μm) 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

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

    PubMed

    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

    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

  18. Study on determination of iron, cobalt, nickel, copper, zinc and manganese in drinking water by solid-phase extraction and RP-HPLC with 2-(2-quinolinylazo)-5-diethylaminophenol as precolumn derivatizing reagent.

    PubMed

    Hu, Qiufen; Yang, Guanyu; Yang, Jihong; Yin, Jiayuan

    2002-12-01

    A new method for the determination of iron, cobalt, nickel, copper, zinc and manganese in drinking water by the reversed-phase high-performance liquid chromatography (RP-HPLC) with 2-(2-quinolinylazo)-5-diethylaminophenol (QADEAP) as precolumn derivatizing reagent was studied in this paper. The iron, cobalt, nickel, copper, zinc, and manganese ions react with QADEAP to form color chelates in the presence of cetyl trimethylammonium bromide (CTMAB) and acetic acid-sodium acetic buffer solution medium of pH 4.0. These chelates were enriched by solid-phase extraction with a Waters Nova-Pak C18 cartridge and eluted the retained chelates from the cartridge with tetrahydrofuran (THF). The enrichment factor of 100 was achieved. Then the chelates were separated on a Waters Nova-Pak C18 column (3.9 x 150 mm, 5 microm) by gradient elution with methanol (containing 0.2% of acetic acid and 0.1% of CTMAB) and 0.05 mol L(-1) acetic acid-sodium acetic buffer solution (containing 0.1% of CTMAB) (pH 4.0) as mobile phase at a flow rate of 0.5 ml min(-1), and monitored with a photodiode array detector from 450 approximately 700 nm. The detection limits (S/N = 3) of iron, cobalt, nickel, copper, zinc and manganese are 0.8, 1.1, 0.9, 1.1, 1.5 and 2.0 ng L(-1), respectively, in the original sample. This method can be applied to determination at the microg L(-1) level of iron, cobalt, nickel, copper, zinc and manganese in drinking water with good results. PMID:12509050

  19. Simultaneous determination of domperidone and Itopride in pharmaceuticals and human plasma using RP-HPLC/UV detection: Method development, validation and application of the method in in-vivo evaluation of fast dispersible tablets.

    PubMed

    Khan, Amjad; Iqbal, Zafar; Khadra, Ibrahim; Ahmad, Lateef; Khan, Abad; Khan, Muhammad Imran; Ullah, Zia; Ismail

    2016-03-20

    Domperidone and Itopride are pro-kinetic agents, regulating the gastric motility and are commonly prescribed as anti emetic drugs. In the present study a simple, rapid and sensitive RP-HPLC/UV method was developed for simultaneous determination of Domperidone and Itopride in pharmaceutical samples and human plasma, using Tenofavir as internal standard. Experimental conditions were optimized and method was validated according to the standard guidelines. Combination of water (pH 3.0) and acetonitrile (65:35 v/v) was used as mobile phase, pumped at the flow rate of 1.5 ml/min. Detector wavelength was set at 210 nm and column oven temperature was 40oC. Unlike conventional liquid-liquid extraction, simple precipitation technique was applied for drug extraction from human plasma using acetonitrile for deprotienation. The method showed adequate separation of both the analytes and best resolution was achieved using Hypersil BDS C8 column (150 mm × 4.6 mm, 5 μm). The method was quite linear in the range of 20-600 ng/ml. Recovery of the method was 92.31% and 89.82% for Domperidone and Itopride, respectively. Retention time of both the analytes and internal standard was below 15 min. The lower limit of detection (LLOD) and lower limit of quantification (LLOQ) for Domperidone were 5 and 10 ng/ml while for Itopride was 12 and 15 ng/ml, respectively. The developed method was successfully applied for in-vivo analysis of fast dispersible tablets of Domperidone in healthy human volunteer. The proposed method was a part of formulation development study and was efficiently applied for determination of the two drugs in various pharmaceutical products and human plasma. PMID:26773534

  20. Quantitative and chemical fingerprint analysis for the quality evaluation of Receptaculum Nelumbinis by RP-HPLC coupled with hierarchical clustering analysis.

    PubMed

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

    2013-01-01

    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-β-d-glucuronide, isorhamnetin-3-O-β-d-galactoside and syringetin-3-O-β-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

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

    PubMed Central

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

    2013-01-01

    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-β-d-glucuronide, isorhamnetin-3-O-β-d-galactoside and syringetin-3-O-β-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

  2. Development of Stability-Indicating Methods for Cefquinome Sulphate

    PubMed Central

    Shantier, Shaza W.; Gadkariem, Elrasheed A.; Adam, Mohamed O.; Mohamed, Magdi A.

    2013-01-01

    The degradation behavior of cefquinome sulphate in alkaline medium at different temperatures was investigated using both first derivative spectrophotometric and HPLC methods. The drug degradation was found to be pH and temperature dependant. The pH-rate profile indicated a first order dependence of Kobs on [OH-] at pHs ranging between 9 and 11. Arrhenius plot obtained at pH 10 was linear between 65° and 100°C. The estimated activation energy of the hydrolysis was found to be 21.1 kcal mol-1. Stability-indicating thin-layer chromatographic method for the separation of the drug and its alkaline hydrolysis product has been developed. PMID:24170991

  3. A stability indicating capillary electrophoresis method for analysis of buserelin.

    PubMed

    Tamizi, Elnaz; Kenndler, Ernst; Jouyban, Abolghasem

    2014-01-01

    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 μm 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 μg/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. PMID:25276180

  4. A Review of Voltage Stability Assessment Techniques with an Improved Voltage Stability Indicator

    NASA Astrophysics Data System (ADS)

    Danish, Mir Sayed Shah; Yona, Atsushi; Senjyu, Tomonobu

    2015-04-01

    A blackout can take place in entire power system or a part of the system due to extreme voltage instability (voltage collapse) that can appear abruptly. Instability prediction and continuous monitoring of the power system performance is, therefore, known exigent. This paper is conducted with a broad overview of the voltage stability indices, which are previously studied in the literature, and have the same foundation during their formulation. Afterward, an improved voltage stability indicator is introduced as a result of the multi-criteria integration and enhancement of the original indices by employing linear algebra methods. It is found that the proposed algorithm can overcome on the probable limitations from calculating point view. Then comparative analysis of the indices is presented in order to reach a unique consensus about the typical techniques of modal analysis (sensitivity, eigenvalue, right eigenvectors, and bus participation factor) as a precise algorithm. Finally, the IEEE 14-bus, and 30-bus test systems are selected to verify the algorithm, and compare the performance of the improved indicator approach with the existing indices.

  5. Stability-Indicating HPLC Method for Posaconazole Bulk Assay

    PubMed Central

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

    2012-01-01

    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 μg 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

  6. Ratio manipulating spectrophotometry versus chemometry as stability indicating methods for cefquinome sulfate determination

    NASA Astrophysics Data System (ADS)

    Yehia, Ali M.; Arafa, Reham M.; Abbas, Samah S.; Amer, Sawsan M.

    2016-01-01

    Spectral resolution of cefquinome sulfate (CFQ) in the presence of its degradation products was studied. Three selective, accurate and rapid spectrophotometric methods were performed for the determination of CFQ in the presence of either its hydrolytic, oxidative or photo-degradation products. The proposed ratio difference, derivative ratio and mean centering are ratio manipulating spectrophotometric methods that were satisfactorily applied for selective determination of CFQ within linear range of 5.0-40.0 μg mL- 1. Concentration Residuals Augmented Classical Least Squares was applied and evaluated for the determination of the cited drug in the presence of its all degradation products. Traditional Partial Least Squares regression was also applied and benchmarked against the proposed advanced multivariate calibration. Experimentally designed 25 synthetic mixtures of three factors at five levels were used to calibrate and validate the multivariate models. Advanced chemometrics succeeded in quantitative and qualitative analyses of CFQ along with its hydrolytic, oxidative and photo-degradation products. The proposed methods were applied successfully for different pharmaceutical formulations analyses. These developed methods were simple and cost-effective compared with the manufacturer's RP-HPLC method.

  7. Storage stability of Bacillus subtilis ethylene oxide biological indicators.

    PubMed Central

    Reich, R R

    1980-01-01

    Bacillus subtilis biological indicators, stored at ambient and freezer conditions for 24 months, demonstrated no statistical difference in ethylene oxide resistance and spore viability from initial production levels. PMID:6766701

  8. Environmental stability of PAH source indices in pyrogenic tars

    SciTech Connect

    Uhler, A.D.; Emsbo-Mattingly, S.D.

    2006-04-15

    Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental contaminants found in soil, sediments, and airborne particulates. The majority of PAHs found in modern soils and sediments arise from myriad anthropogenic petrogenic and pyrogenic sources. Tars and tar products such as creosote produced from the industrial pyrolysis of coal or oil at former manufactured gas plants (MGPs) or in coking retorts are viscous, oily substances that contain significant concentrations of PAH, usually in excess of 30% w/w. Pyrogenic tars and tar products have unique PAH patterns (source signatures) that are a function of their industrial production. Among pyrogenic materials, certain diagnostic ratios of environmentally recalcitrant 4-, 5- and 6-ring PAHs have been identified as useful environmental markers for tracking the signature of tars and petroleum in the environment. The use of selected PAH source ratios is based on the concept that PAHs with similar properties (i.e., molecular weight, partial pressure, solubility, partition coefficients, and biotic/abiotic degradation) will weather at similar rates in the environment thereby yielding stable ratios. The stability of more than 30 high molecular weight PAH ratios is evaluated during controlled studies of tar evaporation and aerobic biodegradation. The starting materials in these experiments consisted of relatively unweathered tars derived from coal and petroleum, respectively. The PAH ratios from these laboratory studies are compared to those measured in PAH residues found in tar-contaminated soils at a former MGP that operated with a carburetted water gas process.

  9. Trifluoroethanol-containing RP-HPLC mobile phases for the separation of transmembrane peptides human glycophorin-A, integrin alpha-1, and p24: analysis and prevention of potential side reactions due to formic acid.

    PubMed

    Hara, Toshiaki; Huang, Yue; Ito, Akihiro; Kawakami, Toru; Hojo, Hironobu; Murata, Michio

    2015-02-01

    Reversed-phase high-pressure liquid chromatography analysis and purification of three hydrophobic, aggregation-prone peptides, composed mainly of the transmembrane (TM) sequence, were performed using elution systems containing 2,2,2-trifluoroethanol (TFE). The addition of 10-16% TFE to a common mobile phase, such as a water/acetonitrile/propanol (PrOH) or a water/PrOH/formic acid system, markedly improved the chromatographic separation of these peptides. The superior performance of TFE-containing systems in separating peptides over water/PrOH/formic acid systems [Bollhagen R. et al., J. Chromatogr. A, 1995; 711: 181-186.] clearly demonstrated that adding TFE to the mobile phase is one of best methods for TM-peptide purification. Characterization of the potential side reactions using MALDI and ESI-LIT/Orbitrap mass spectrometry indicated that prolonged incubation of peptides in a mixture of TFE-formic acid possibly induces O-formylation of the Ser residue and N-formylation of the N-terminus of peptides. The conditions for selective removal of the formyl groups from TM peptides were also screened. We believe that these results will expand our ability to analyze and prepare hydrophobic, aggregation-prone TM peptides and proteins. PMID:25504594

  10. RP-HPLC characterization of lupenone and β-sitosterol in rhizoma musae and evaluation of the anti-diabetic activity of lupenone in diabetic Sprague-Dawley rats.

    PubMed

    Xu, Feng; Wu, Hongmei; Wang, Xiangpei; Yang, Ye; Wang, Yuanmin; Qian, Haibing; Zhang, Yanyan

    2014-01-01

    With the aim of characterizing the active ingredients lupenone and β-sitosterol in Rhizoma Musae samples a reversed-phase HPLC method for the separation of these two compounds in Rhizoma Musae samples was developed (regression coefficient>0.9996). The method was further applied to quantify lupenone and β-sitosterol content in Rhizoma Musae samples cultured in different growth environments. Different variables such as geographical location, growth stage, and harvest time, demonstrated differential effects on lupenone and β-sitosterol levels. Moreover, we determined the optimum conditions for cultivation and harvesting of Rhizoma Musae herbs. Lupenone administration caused a significant reduction in fasting blood glucose (FBG) levels in diabetic rats at doses of 1.78, 5.33, and 16.00 mg·kg⁻¹·day⁻¹ for 14 days, the glycated hemoglobin (HbA1c) levels of diabetic rats also significantly reduced at doses of 5.33, and 16.00 mg·kg⁻¹·day⁻¹, indicating a robust antidiabetic activity. To our knowledge, this is the first report of an optimized HPLC method successfully applied to quantify lupenone and β-sitosterol, and its applicability in optimizing Rhizoma Musae growth. Animal experiments also showed for the first time that lupenone from Rhizoma Musae has anti-diabetic activity. PMID:25207716

  11. Development of New Method for Simultaneous Analysis of Piracetam and Levetiracetam in Pharmaceuticals and Biological Fluids: Application in Stability Studies

    PubMed Central

    Siddiqui, Farhan Ahmed; Sher, Nawab; Shafi, Nighat; Wafa Sial, Alisha; Ahmad, Mansoor; Mehjebeen

    2014-01-01

    RP-HPLC ultraviolet detection simultaneous quantification of piracetam and levetiracetam has been developed and validated. The chromatography was obtained on a Nucleosil C18 column of 25 cm × 0.46 cm, 10 μm, dimension. The mobile phase was a (70 : 30 v/v) mixture of 0.1 g/L of triethylamine and acetonitrile. Smooth flow of mobile phase at 1 mL/min was set and 205 nm wavelength was selected. Results were evaluated through statistical parameters which qualify the method reproducibility and selectivity for the quantification of piracetam, levetiracetam, and their impurities hence proving stability-indicating properties. The proposed method is significantly important, permitting the separation of the main constituent piracetam from levetiracetam. Linear behavior was observed between 20 ng/mL and 10000 ng/mL for both drugs. The proposed method was checked in bulk drugs, dosage formulations, physiological condition, and clinical investigations and excellent outcome was witnessed. PMID:25114921

  12. Evaluation of oxygen utilization as an indicator of municipal solid-waste compost stability

    SciTech Connect

    Zimmerman, R.A.

    1991-01-01

    This research evaluated oxygen utilization parameters as indicators of MSW compost stability. Parameters evaluated were the oxygen utilization rate (OUR), specific oxygen uptake rate (SOUR), five-day biochemical oxygen demand, and chemical oxygen demand. In addition, other suggested indicators of stability were investigated including percent volatile solids, volatile solids reduction, nitrogen content, carbon: nitrogen ratio, and reheating potential (RP). OUR is a measure of the rate of oxygen utilization by the microorganisms in the decomposition of organic matter in compost. OUR was observed to be sensitive to the degree of stabilization and decreased with increasing compost age and stability. OUR values near zero indicate that the compost microorganisms are in a state of endogenous respiration, which is characteristic of a stable compost. Therefore, OUR is an excellent indicator of stability. A number of disadvantages are associated with OUR for practical application. Therefore, other parameters were evaluated as indicators of stability based on their statistical correlation to OUR. RP exhibited the strongest correlation to OUR. In combination, RP and SOUR were the two parameters which exhibited the strongest correlation to OUR. OUR, RP, and SOUR are all measures of microbial activity which reflect the degree of organic decomposition, and therefore, stability. Based on the results of this research; OUR, RP, and SOUR are useful parameters in assessing compost stability.

  13. The Effects of Balance Training on Static and Dynamic Postural Stability Indices After Acute ACL Reconstruction

    PubMed Central

    Akbari, Asghar; Ghiasi, Fateme; Mir, Mohsen; Hosseinifar, Mohammad

    2016-01-01

    Background: Proprioception and postural stability play an important role in knee movements. However, there are controversies about the overall recovery time of proprioception following knee surgery and onset of balance and neuromuscular training after ACL reconstruction. Therefore, it is necessary to evaluate the effect of balance training in early stage of knee rehabilitation after anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to evaluate the effect of balance exercises on postural stability indices in subjects with anterior cruciate ligament (ACL) reconstruction. Methods: The study was a controlled randomized trial study. Twenty four patients who had ACL reconstructed (balance training group) and twenty four healthy adults without any knee injury (control group) were recruited in the study. The balance exercises group performed balance exercises for 2 weeks. 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. T-tests were used for statistical analysis (p<0.05). Results: Results showed that amount of static stability indices did not change after training and there were not significant differences in static stability indices before and after balance training (p>0.05). Although amount of dynamic stability indices decreased, there were not significant differences in dynamic stability indices before and after balance training (p>0.05). Amount of dynamic stability indices were decreased in balance training group, however, there were not significant differences between groups (p>0.05). Conclusion: These results support that balance exercise could partially improved dynamic stability indices in early stage of ACL reconstruction rehabilitation. The results of this study suggest that balance exercises should be part of the rehabilitation program following ACL reconstruction. PMID

  14. Sorption of benzotriazoles under the conditions of RP HPLC

    NASA Astrophysics Data System (ADS)

    Dzhabieva, S. A.; Kurbatova, S. V.; Belousova, Z. P.

    2016-02-01

    The results of a chromatographic study of sorption of several benzotriazole derivatives on octadecyl silica gel were reported. The physicochemical and electronic parameters of benzotriazoles were calculated. The effect of the structure of analyte molecules and eluent composition on chromatographic retention of these substances was analyzed.

  15. Simultaneous Estimation of Nebivolol Hydrochloride and Valsartan using RP HPLC

    PubMed Central

    Kokil, S. U.; Bhatia, M. S.

    2009-01-01

    In this study, a rapid, precise, accurate, specific and sensitive ion-paired reverse phase liquid chromatographic method has been developed for the simultaneous estimation of nebivolol hydrochloride and valsartan in their capsule formulation. The chromatographic method was standardized using a HIQ sil C18 column (250×4.6 mm i.d., 5 μm particle size) with UV detection at 289 nm and flow rate of 1 ml/min. The mobile phase consisting of methanol:water (80:20 v/v) with addition of 0.1 percent 1-hexanesulfonic acid monohydrate sodium salt as an ion-pairing reagent was selected. The method was validated and produced accurate and precise results for estimation of the two drugs. PMID:20336202

  16. Separation of kafirins on surface porous RP-HPLC columns

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Surface porous HPLC columns were investigated for the separation of kafarins, storage proteins of grain sorghum. Kafirins were successfully separated using C3, C8 and C18 surface porous stationary phases in less than 17 min. Separations using a monolithic C18 stationary phase were also developed ...

  17. Optimal placement of unified power flow controllers to improve dynamic voltage stability using power system variable based voltage stability indices.

    PubMed

    Albatsh, Fadi M; Ahmad, Shameem; Mekhilef, Saad; Mokhlis, Hazlie; Hassan, M A

    2015-01-01

    This study examines a new approach to selecting the locations of unified power flow controllers (UPFCs) in power system networks based on a dynamic analysis of voltage stability. Power system voltage stability indices (VSIs) including the line stability index (LQP), the voltage collapse proximity indicator (VCPI), and the line stability index (Lmn) are employed to identify the most suitable locations in the system for UPFCs. In this study, the locations of the UPFCs are identified by dynamically varying the loads across all of the load buses to represent actual power system conditions. Simulations were conducted in a power system computer-aided design (PSCAD) software using the IEEE 14-bus and 39- bus benchmark power system models. The simulation results demonstrate the effectiveness of the proposed method. When the UPFCs are placed in the locations obtained with the new approach, the voltage stability improves. A comparison of the steady-state VSIs resulting from the UPFCs placed in the locations obtained with the new approach and with particle swarm optimization (PSO) and differential evolution (DE), which are static methods, is presented. In all cases, the UPFC locations given by the proposed approach result in better voltage stability than those obtained with the other approaches. PMID:25874560

  18. Optimal Placement of Unified Power Flow Controllers to Improve Dynamic Voltage Stability Using Power System Variable Based Voltage Stability Indices

    PubMed Central

    Albatsh, Fadi M.; Ahmad, Shameem; Mekhilef, Saad; Mokhlis, Hazlie; Hassan, M. A.

    2015-01-01

    This study examines a new approach to selecting the locations of unified power flow controllers (UPFCs) in power system networks based on a dynamic analysis of voltage stability. Power system voltage stability indices (VSIs) including the line stability index (LQP), the voltage collapse proximity indicator (VCPI), and the line stability index (Lmn) are employed to identify the most suitable locations in the system for UPFCs. In this study, the locations of the UPFCs are identified by dynamically varying the loads across all of the load buses to represent actual power system conditions. Simulations were conducted in a power system computer-aided design (PSCAD) software using the IEEE 14-bus and 39- bus benchmark power system models. The simulation results demonstrate the effectiveness of the proposed method. When the UPFCs are placed in the locations obtained with the new approach, the voltage stability improves. A comparison of the steady-state VSIs resulting from the UPFCs placed in the locations obtained with the new approach and with particle swarm optimization (PSO) and differential evolution (DE), which are static methods, is presented. In all cases, the UPFC locations given by the proposed approach result in better voltage stability than those obtained with the other approaches. PMID:25874560

  19. Subtle alternating electrocardiographic morphology as an indicator of decreased cardiac electrical stability

    NASA Technical Reports Server (NTRS)

    Smith, J. M.; Blue, B.; Clancy, E.; Valeri, C. R.; Cohen, R. J.

    1985-01-01

    Observations from finite-element computer models, together with analytic developments based on percolation theory have suggested that subtle fluctuations of ECG morphology might serve as an indicator diminished cardiac electrical stability. With fixed-rate atrial pacing in canines, we have previously observed a pattern of alternation in T wave energy which correlated with cardiac electrical stability. We report here on a series of 20 canine experiments in which cardiac electrical stability (measured via Ventricular Fibrillation Threshold determination) was compared to a non-degenerate, multidimensional measurement of the degree of alternating activity present in the ECG complex morphology. The decrease in cardiac electrical stability brought on by both coronary artery occlusion and systemic hypothermia was consistently accompanied by subtle alternation in ECG morphology, with the absolute degree of alternating activity being significantly (negatively) correlated with cardiac electrical stability.

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

    PubMed Central

    Akbari, Asghar; Sarmadi, Alireza; Zafardanesh, Parisa

    2014-01-01

    [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

  1. Development and Validation of Stability-indicating High Performance Liquid Chromatographic Method for the Estimation of Everolimus in Tablets

    PubMed Central

    Sharmila, D.; Rao, A. Lakshmana; Kalyani, L.

    2015-01-01

    The present study depicts the development of a validated reversed-phase high performance liquid chromatographic method for the determination of the everolimus in presence of degradation products or pharmaceutical excipients. Stress study was performed on everolimus and it was found that it degrade sufficiently in oxidizing and acidic conditions but less degradation was found in alkaline, neutral, thermal and photolytic conditions. The separation was carried out on Hypersil BDS C18 column (100×4.6 mm, 5 μ) column having particle size 5 μ using acetate buffer:acetonitrile (50:50 v/v) with pH 6.5 adjusted with orthophosphoric acid as mobile phase at flow rate of 1 ml/min. The wavelength of the detection was 280 nm. A retention time (Rt) nearly 3.110 min was observed. The calibration curve for everolimus was linear (r2=0.999) from range of 25-150 μg/ml with limit of detection and limit of quantification of 0.036 μg/ml and 0.109 μg/ml, respectively. Analytical validation parameters such as selectivity, specificity, linearity, accuracy and precision were evaluated and relative standard deviation value for all the key parameters were less than 2.0%. The recovery of the drug after standard addition was found to be 100.55%. Thus, the developed RP-HPLC method was found to be suitable for the determination of everolimus in tablets containing various excipients. PMID:26798176

  2. Development and Validation of Stability-indicating High Performance Liquid Chromatographic Method for the Estimation of Everolimus in Tablets.

    PubMed

    Sharmila, D; Rao, A Lakshmana; Kalyani, L

    2015-01-01

    The present study depicts the development of a validated reversed-phase high performance liquid chromatographic method for the determination of the everolimus in presence of degradation products or pharmaceutical excipients. Stress study was performed on everolimus and it was found that it degrade sufficiently in oxidizing and acidic conditions but less degradation was found in alkaline, neutral, thermal and photolytic conditions. The separation was carried out on Hypersil BDS C18 column (100×4.6 mm, 5 μ) column having particle size 5 μ using acetate buffer:acetonitrile (50:50 v/v) with pH 6.5 adjusted with orthophosphoric acid as mobile phase at flow rate of 1 ml/min. The wavelength of the detection was 280 nm. A retention time (Rt) nearly 3.110 min was observed. The calibration curve for everolimus was linear (r(2)=0.999) from range of 25-150 μg/ml with limit of detection and limit of quantification of 0.036 μg/ml and 0.109 μg/ml, respectively. Analytical validation parameters such as selectivity, specificity, linearity, accuracy and precision were evaluated and relative standard deviation value for all the key parameters were less than 2.0%. The recovery of the drug after standard addition was found to be 100.55%. Thus, the developed RP-HPLC method was found to be suitable for the determination of everolimus in tablets containing various excipients. PMID:26798176

  3. Certain Actions from the Functional Movement Screen Do Not Provide an Indication of Dynamic Stability.

    PubMed

    Lockie, Robert G; Callaghan, Samuel J; Jordan, Corrin A; Luczo, Tawni M; Jeffriess, Matthew D; Jalilvand, Farzad; Schultz, Adrian B

    2015-09-29

    Dynamic stability is an essential physical component for team sport athletes. Certain Functional Movement Screen (FMS) exercises (deep squat; left- and right-leg hurdle step; left- and right-leg in-line lunge [ILL]; left- and right-leg active straight-leg raise; and trunk stability push-up [TSPU]) have been suggested as providing an indication of dynamic stability. No research has investigated relationships between these screens and an established test of dynamic stability such as the modified Star Excursion Balance Test (mSEBT), which measures lower-limb reach distance in posteromedial, medial, and anteromedial directions, in team sport athletes. Forty-one male and female team sport athletes completed the screens and the mSEBT. Participants were split into high-, intermediate-, and low-performing groups according to the mean of the excursions when both the left and right legs were used for the mSEBT stance. Any between-group differences in the screens and mSEBT were determined via a one-way analysis of variance with Bonferroni post hoc adjustment (p < 0.05). Data was pooled for a correlation analysis (p < 0.05). There were no between-group differences in any of the screens, and only two positive correlations between the screens and the mSEBT (TSPU and right stance leg posteromedial excursion, r = 0.37; left-leg ILL and left stance leg posteromedial excursion, r = 0.46). The mSEBT clearly indicated participants with different dynamic stability capabilities. In contrast to the mSEBT, the selected FMS exercises investigated in this study have a limited capacity to identify dynamic stability in team sport athletes. PMID:26557187

  4. Certain Actions from the Functional Movement Screen Do Not Provide an Indication of Dynamic Stability

    PubMed Central

    Lockie, Robert G.; Callaghan, Samuel J.; Jordan, Corrin A.; Luczo, Tawni M.; Jeffriess, Matthew D.; Jalilvand, Farzad; Schultz, Adrian B.

    2015-01-01

    Dynamic stability is an essential physical component for team sport athletes. Certain Functional Movement Screen (FMS) exercises (deep squat; left- and right-leg hurdle step; left- and right-leg in-line lunge [ILL]; left- and right-leg active straight-leg raise; and trunk stability push-up [TSPU]) have been suggested as providing an indication of dynamic stability. No research has investigated relationships between these screens and an established test of dynamic stability such as the modified Star Excursion Balance Test (mSEBT), which measures lower-limb reach distance in posteromedial, medial, and anteromedial directions, in team sport athletes. Forty-one male and female team sport athletes completed the screens and the mSEBT. Participants were split into high-, intermediate-, and low-performing groups according to the mean of the excursions when both the left and right legs were used for the mSEBT stance. Any between-group differences in the screens and mSEBT were determined via a one-way analysis of variance with Bonferroni post hoc adjustment (p < 0.05). Data was pooled for a correlation analysis (p < 0.05). There were no between-group differences in any of the screens, and only two positive correlations between the screens and the mSEBT (TSPU and right stance leg posteromedial excursion, r = 0.37; left-leg ILL and left stance leg posteromedial excursion, r = 0.46). The mSEBT clearly indicated participants with different dynamic stability capabilities. In contrast to the mSEBT, the selected FMS exercises investigated in this study have a limited capacity to identify dynamic stability in team sport athletes. PMID:26557187

  5. Development and Validation of Stability-Indicating Derivative Spectrophotometric Methods for Determination of Dronedarone Hydrochloride

    NASA Astrophysics Data System (ADS)

    Chadha, R.; Bali, A.

    2016-05-01

    Rapid, sensitive, cost effective and reproducible stability-indicating derivative spectrophotometric methods have been developed for the estimation of dronedarone HCl employing peak-zero (P-0) and peak-peak (P-P) techniques, and their stability-indicating potential assessed in forced degraded solutions of the drug. The methods were validated with respect to linearity, accuracy, precision and robustness. Excellent linearity was observed in concentrations 2-40 μg/ml (r 2 = 0.9986). LOD and LOQ values for the proposed methods ranged from 0.42-0.46 μg/ml and 1.21-1.27 μg/ml, respectively, and excellent recovery of the drug was obtained in the tablet samples (99.70 ± 0.84%).

  6. Development and Validation of Stability-Indicating Derivative Spectrophotometric Methods for Determination of Dronedarone Hydrochloride

    NASA Astrophysics Data System (ADS)

    Chadha, R.; Bali, A.

    2016-05-01

    Rapid, sensitive, cost effective and reproducible stability-indicating derivative spectrophotometric methods have been developed for the estimation of dronedarone HCl employing peak-zero (P-0) and peak-peak (P-P) techniques, and their stability-indicating potential assessed in forced degraded solutions of the drug. The methods were validated with respect to linearity, accuracy, precision and robustness. Excellent linearity was observed in concentrations 2-40 μg/ml ( r 2 = 0.9986). LOD and LOQ values for the proposed methods ranged from 0.42-0.46 μg/ml and 1.21-1.27 μg/ml, respectively, and excellent recovery of the drug was obtained in the tablet samples (99.70 ± 0.84%).

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

    PubMed

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

    2013-03-01

    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-μm, 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

  8. Radon as an Indicator of Nocturnal Atmospheric Stability: A Simplified Theoretical Approach

    NASA Astrophysics Data System (ADS)

    Omori, Yasutaka; Nagahama, Hiroyuki

    2016-02-01

    Nocturnal evolution of radon concentration and the height of a box model, which is determined from radon concentration and local radon flux at the ground, are used as indicators of nocturnal atmospheric stability in single-height observations. However, quantitative relationships between these indicators and meteorological conditions, including the turbulent diffusion coefficient, have not yet been well established. Here, we construct a simple model based on the heat exchange process of the lower atmosphere to relate these parameters. The model neglects radiative flux divergence and assumes a uniform constant radon flux, making it most applicable to low wind conditions at sites well-removed from coastal influences, when advective effects are minimal. The model shows that the box height (equivalent mixing height) can be determined from near-surface parameters including sensible heat flux and the decrease in potential temperature after sunset. For these parameters, static stability and mechanical mixing components are incorporated. In addition, the constructed equations suggest the equivalent mixing height is proportional to the inversion layer height with a slope that depends on the vertical profile of potential temperature. The equivalent mixing height can be also related to the turbulent diffusion intensity. We demonstrate that radon observations at a single height are useful for monitoring nocturnal atmospheric stability.

  9. Stability-indicating LC method for the simultaneous determination of lisinopril and hydrochlorothiazide.

    PubMed

    de Diego, Marta; Soto, Jorge; Mennickent, Sigrid

    2014-01-01

    A simple and rapid stability-indicating liquid chromatographic method was developed and validated for the simultaneous determination of lisinopril and hydrochlorotiazide (HCTZ) in drug substances and dosage forms in the presence of degradation products. Forced degradation studies were conducted on the pure drugs under hydrolytic, oxidative, thermal and photolytic conditions. A chromatographic separation of the two drugs and its degradation products was achieved with an RP-18 column, using methanol, acetonitrile and phosphate buffer (pH 7.1; 0.05 M) (15:15:70, v/v/v) as mobile phase at a flow rate of 0.8 mL min(-1) and UV detection at 210 nm. Lisinopril and HCTZ were well resolved from its degradation products showing the stability-indicating capability of the method. The described method was linear over a range of 40-200 µg mL(-1) for lisinopril and 25-175 µg mL(-1) for HCTZ. The assay was also selective, accurate and precise for lisinopril and HCTZ determination. This method represents an alternative to the United States Pharmacopeia (USP) method showing shorter retention time. The method was successfully applied for determination of lisinopril and HCTZ in combined commercial tablets. The results showed that the proposed method was found to be suitable for quantitative determination and the stability study of lisinopril and HCTZ in pharmaceutical samples. PMID:24297524

  10. Soil aggregate stability as an indicator for eco-engineering effectiveness?

    NASA Astrophysics Data System (ADS)

    Graf, Frank

    2015-04-01

    Eco-engineering aims at stabilising soil and slopes by applying technical and biological measures. Engineering structures are commonly well defined, immediately usable and operative, and their stability effects quantifiable and verifiable. Differently, the use of plants requires more restrictive boundary conditions and the protection potential is rarely easily calculable and develop-ing as a function of growth rate. Although the use of vegetation is widely appreciated and their stabilising effect recognised, there is an increasing demand on sound facts on its efficiency, in particular, in relation to time. Conclusively, a certain necessity has been recognised to monitor, assess and quantify the effectiveness of ecological restora-tion measures in order to facilitate the transfer of technology and knowledge. Recent theoretical models emphasize the im-portance of taking an integrated monitoring approach that considers multiple variables. However, limited financial and time resources often prevent such comprehensive assessments. A solution to this problem may be to use integrated indicators that reflect multiple aspects and, therefore, allow extensive information on ecosystem status to be gathered in a relatively short time. Among various other indicators, such as fractal dimension of soil particle size distribution or microbiological parameters, soil aggregate stability seems the most appropriate indicator with regard to protecting slopes from superficial soil failure as it is critical to both plant growth and soil structure. Soil aggregation processes play a crucial role in re-establishing soil structure and function and, conclusively, for successful and sustainable re-colonisation. Whereas the key role of soil aggregate stability in ecosystem functioning is well known concerning water, gas, and nutrient fluxes, only limited information is available with regard to soil mechanical and geotechnical aspects. Correspondingly, in the last couple of years several studies

  11. Stability-indicating HPLC method for the determination of darunavir ethanolate.

    PubMed

    Reddy, B V Rami; Jyothi, G; Reddy, B S; Raman, N V V S S; Reddy, K Subhash Chander; Rambabu, C

    2013-01-01

    A novel stability-indicating reversed-phase high-performance liquid chromatographic (HPLC) method has been developed for the quantitative determination of darunavir ethanolate, an HIV-1 protease inhibitor. The chromatographic separation was achieved using an X-Bridge C18 (150 × 4.6 mm × 3.5 µm) HPLC column in isocratic mode employing 0.01M ammonium formate (pH.3.0) buffer and acetonitrile in the ratio of 55:45 (v/v) with a flow rate of 1.0 mL/min. The detector wavelength was monitored at 265 nm and the column temperature was maintained at 30°C. Darunavir ethanolate was exposed to thermal, photolytic, acid, base and oxidative stress conditions. Considerable degradation of the drug substance was found to occur under acid, base and oxidative stress conditions. The peak homogeneity data of darunavir ethanolate obtained by photodiode array detection demonstrated the specificity of the method in the presence of degradants. The degradation products were well resolved from primary peak of darunavir, indicating that the method is specific and stability-indicating. The HPLC method was validated as per International Conference on Harmonization guidelines with respect to specificity, precision, linearity, accuracy and robustness. Regression analysis showed a correlation coefficient value greater than 0.999. The accuracy of the method was established based on the recovery obtained for darunavir ethanolate. PMID:23097581

  12. Novel indication for posterior dynamic stabilization: Correction of disc tilt after lumbar total disc replacement

    PubMed Central

    Cheng, Wayne K.; Palmer, Daniel Kyle; Jadhav, Vikram

    2011-01-01

    Background The increase in total disc replacement procedures performed over the last 5 years has increased the occurrence of patients presenting with postoperative iatrogenic deformity requiring revision surgery. Proposed salvage treatments include device retrieval followed by anterior lumbar interbody fusion or posterior fusion. We propose a novel approach for the correction of disc tilt after total disc replacement using a posterior dynamic stabilization system. Methods Pedicle screws can be inserted either in an open manner or percutaneously by standard techniques under fluoroscopy. The collapsed side is expanded, and the convex side is compressed. Universal spacers are placed bilaterally, with the spacer on the collapsed side being taller by 6 mm. Cords are threaded through the spacers and pulled into place with the tensioning instrument. Extra tension is applied to the convex side, and the wound is closed by standard techniques. Results Three patients presenting with tilted total disc replacement devices underwent corrective surgery with posterior dynamic stabilization. Radiographs confirmed correction of deformity in all cases. Conclusions/Level of Evidence This technical note presents a novel indication for posterior dynamic stabilization and describes its surgical application to the correction of disc tilt after total disc replacement. This is level V evidence. PMID:25802667

  13. PrimeSupplier Cross-Program Impact Analysis and Supplier Stability Indicator Simulation Model

    NASA Technical Reports Server (NTRS)

    Calluzzi, Michael

    2009-01-01

    PrimeSupplier, a supplier cross-program and element-impact simulation model, with supplier solvency indicator (SSI), has been developed so that the shuttle program can see early indicators of supplier and product line stability, while identifying the various elements and/or programs that have a particular supplier or product designed into the system. The model calculates two categories of benchmarks to determine the SSI, with one category focusing on agency programmatic data and the other focusing on a supplier's financial liquidity. PrimeSupplier was developed to help NASA smoothly transition design, manufacturing, and repair operations from the Shuttle program to the Constellation program, without disruption in the industrial supply base.

  14. On the Calculation of Lyapunov Indicators with Post-stabilization in a Weyl Field

    NASA Astrophysics Data System (ADS)

    Wu, Xin; Zhang, Hong; Wan, Xiao-Sheng

    2006-04-01

    We present details of a work aiming at the overestimation of Lyapunov exponents defined by the geodesic deviation equations in the previous work. The geodesic deviation vector with post-stabilization is used to compute the fast Lyapunov indicator, considered to be a very sensitive tool for discrimination between ordered or weakly chaotic motions. We make a detailed study of the dynamics in the superposed Weyl field between a black hole and shell of octopoles by using the fast Lyapunov indicator with the Poincaré surface of section. In particular, we examine the effects on the dynamics around the fixed points, of varying one of the three parameters (specific energy E, specific angular momentum L and octopolar moment Script O), while keeping the other two fixed, and identify the intervals of the varying parameter where the motion is regular or chaotic.

  15. Evaluation of the stability indices for the thunderstorm forecasting in the region of Belgrade, Serbia

    NASA Astrophysics Data System (ADS)

    Vujović, D.; Paskota, M.; Todorović, N.; Vučković, V.

    2015-07-01

    The pre-convective atmosphere over Serbia during the ten-year period (2001-2010) was investigated using the radiosonde data from one meteorological station and the thunderstorm observations from thirteen SYNOP meteorological stations. In order to verify their ability to forecast a thunderstorm, several stability indices were examined. Rank sum scores (RSSs) were used to segregate indices and parameters which can differentiate between a thunderstorm and no-thunderstorm event. The following indices had the best RSS values: Lifted index (LI), K index (KI), Showalter index (SI), Boyden index (BI), Total totals (TT), dew-point temperature and mixing ratio. The threshold value test was used in order to determine the appropriate threshold values for these variables. The threshold with the best skill scores was chosen as the optimal. The thresholds were validated in two ways: through the control data set, and comparing the calculated indices thresholds with the values of indices for a randomly chosen day with an observed thunderstorm. The index with the highest skill for thunderstorm forecasting was LI, and then SI, KI and TT. The BI had the poorest skill scores.

  16. Stability-Indicating HPLC Determination of Trandolapril in Bulk Drug and Pharmaceutical Dosage Forms

    PubMed Central

    Al-Hawash, Leena A.; Shakya, Ashok K.; Saleem, Maher L.

    2015-01-01

    A rapid, simple, accurate, precise, economical, robust, and stability indicating reverse phase HPLC-PDA procedure has been developed and validated for the determination of trandolapril. The trandolapril was separated isocratically on Hypersil-Gold C18 column (250 mm × 4.6 mm, 5 μm) with a mobile phase consisting of 50% acetonitrile and 50% water (containing 0.025% triethylamine, pH 3.0 ± 0.1), at 25 ± 2°C. Retention time of the drug was ~4.6 min. The eluted compounds were monitored and identified at 210 nm. The linearity of the method was excellent (r2 > 0.9999) over the concentration range of 1–24 μg/mL; the limit of detection (LOD) and limit of quantitation (LOQ) were 0.0566 μg/mL and 0.1715 μg/mL, respectively. The overall precision was less than 2%. Mean recovery of trandolapril was more than 99%; no interference was found from the component present in the preparation. Stability studies indicate that the drug was stable to sunlight and UV light. The drug gives 6 different oxidative products on exposure to hydrogen peroxide. Slight degradation was observed in acidic condition. Degradation was higher in the alkaline condition compared to other conditions. The robustness of the method was studied using factorial design experiment. PMID:25802524

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

    PubMed

    Liew, Kai Bin; Peh, Kok Khiang

    2014-01-01

    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

  18. Stability-indicating HPLC determination of trandolapril in bulk drug and pharmaceutical dosage forms.

    PubMed

    Al-Hawash, Leena A; Shakya, Ashok K; Saleem, Maher L

    2015-01-01

    A rapid, simple, accurate, precise, economical, robust, and stability indicating reverse phase HPLC-PDA procedure has been developed and validated for the determination of trandolapril. The trandolapril was separated isocratically on Hypersil-Gold C18 column (250 mm × 4.6 mm, 5 μm) with a mobile phase consisting of 50% acetonitrile and 50% water (containing 0.025% triethylamine, pH 3.0 ± 0.1), at 25 ± 2°C. Retention time of the drug was ~4.6 min. The eluted compounds were monitored and identified at 210 nm. The linearity of the method was excellent (r (2) > 0.9999) over the concentration range of 1-24 μg/mL; the limit of detection (LOD) and limit of quantitation (LOQ) were 0.0566 μg/mL and 0.1715 μg/mL, respectively. The overall precision was less than 2%. Mean recovery of trandolapril was more than 99%; no interference was found from the component present in the preparation. Stability studies indicate that the drug was stable to sunlight and UV light. The drug gives 6 different oxidative products on exposure to hydrogen peroxide. Slight degradation was observed in acidic condition. Degradation was higher in the alkaline condition compared to other conditions. The robustness of the method was studied using factorial design experiment. PMID:25802524

  19. Determination of rupatadine in pharmaceutical formulations by a validated stability-indicating MEKC method.

    PubMed

    Nogueira, Daniele Rubert; da Silva Sangoi, Maximiliano; da Silva, Lucélia Magalhães; Todeschini, Vítor; Dalmora, Sérgio Luiz

    2008-09-01

    A stability-indicating MEKC was developed and validated for the analysis of rupatadine in tablet dosage forms, using nimesulide as internal standard. The MEKC method was performed on a fused-silica capillary (50 microm id; effective length, 40 cm). The BGE consisted of 15 mM borate buffer and 25 mM anionic detergent SDS solution at pH 10. The capillary temperature was maintained at 35 degrees C and the applied voltage was 25 kV. The injection was performed using the hydrodynamic mode at 50 mbar for 5 s, with detection by photodiode array detector set at 205 nm. The method was linear in the range of 0.5-150 microg/mL (r2=0.9996). The specificity and stability-indicating capability of the method were proven through degradation studies inclusive by MS, and showing also that there was no interference of the excipients and no increase of the cytotoxicity. The accuracy was 99.98% with bias lower than 1.06%. The LOD and LOQ were 0.1 and 0.5 microg/mL, respectively. The proposed method was successfully applied for the quantitative analysis of rupatadine in pharmaceutical formulations, and the results were compared to a validated RP-LC method, showing non-significant difference (p>0.05). PMID:18693320

  20. Stress degradation studies and stability-indicating TLC-densitometric method of glycyrrhetic acid

    PubMed Central

    2013-01-01

    Background Glycyrrhetic acid, a pentacyclic triterpenoid, possesses a broad range of pharmacological activities and serves as template to synthesize many bioactive drugs. This paper describes a simple, accurate, and sensitive stability-indicating TLC densitometric method for the determination of glycyrrhetic acid and its degradation product as per the ICH guidelines. Results Separation was carried out on TLC aluminium sheet pre-coated with silica gel 60F254 using chloroform, methanol and formic acid (9:0.9:0.1, v/v). Compact spot for glycyrrhetic acid was found at Rf value of 0.42 ± 0.03. Densitometric analysis was carried out in the absorbance mode at λmax 254 nm. Glycyrrhetic acid was found to be stable to the exposure of base, neutral, oxidation, dry heating treatment and wet heating treatment, but showed degradation under acidic and photochemical conditions. Moreover, fragmentation pattern of glycyrrhetic acid was developed by using a positive ion electrospray ionization quadrupole time-of-flight mass spectrometry (ESI-QqTOF-MS/MS) hybrid instrument. A photo-degraded product was characterized through comparison of mass spectrometric studies with glycyrrhetic acid. Conclusion The developed stability-indicating TLC-densitometric method can be applied for routine analysis of glycyrrhetic acid in the presence of its degradation products. PMID:23327365

  1. Postural stability of biped robots and the foot-rotation indicator (FRI) point

    SciTech Connect

    Goswami, A.

    1999-06-01

    The focus of this paper is the problem of foot rotation in biped robots during the single-support phase. Foot rotation is an indication of postural instability, which should be carefully treated in a dynamically stable walk and avoided altogether in a statically stable walk. The author introduces the foot-rotation indicator (FRI) point, which is a point on the foot/ground-contact surface where the net ground-reaction force would have to act to keep the foot stationary. To ensure no foot rotation, the FRI point must remain within the convex hull of the foot-support area. In contrast with the ground projection of the center of mass (GCoM), which is a static criterion, the FRI point incorporates robot dynamics. As opposed to the center of pressure (CoP) -- better known as the zero-moment point (ZMP) in the robotics literature -- which may not leave the support area, the FRI point may leave the area. In fact, the position of the FRI point outside the footprint indicates the direction of the impending rotation and the magnitude of rotational moment acting on the foot. Owing to these important properties, the FRI point helps not only to monitor the state of postural stability of a biped robot during the entire gait cycle, but indicates the severity of instability of the gait as well. In response to a recent need, the paper also resolves the misconceptions surrounding the CoP/ZMP equivalence.

  2. Stability-indicating HPTLC determination of ambroxol hydrochloride in bulk drug and pharmaceutical dosage form.

    PubMed

    Jain, P S

    2010-01-01

    A simple, selective, precise, and stability-indicating high-performance thin-layer chromatographic (HPTLC) method for the analysis of ambroxol hydrochloride both as a bulk drug and in formulations was developed and validated. The method employed HPTLC aluminium plates precoated with silica gel 60F-254 as the stationary phase. The solvent system consisted of methanol-triethylamine (4:6 v/v). The system was found to give a compact spot for ambroxol hydrochloride (R(f) value of 0.53 +/- 0.02). Densitometric analysis of ambroxol hydrochloride was carried out in the absorbance mode at 254 nm. The linear regression analysis data for the calibration plots showed good linear relationship with r(2) = 0.9966 +/- 0.0013 with respect to peak area in the concentration range 100-1000 ng/spot. The mean value +/- standard deviation of slope and intercept were 164.85 +/- 0.72 and 1168.3 +/- 8.26 with respect to peak area. The method was validated for precision, recovery, and robustness. The limits of detection and quantitation were 10 and 30 ng/spot, respectively. Ambroxol hydrochloride was subjected to oxidation and thermal degradation. The drug undergoes degradation under oxidation and heat conditions. This indicates that the drug is susceptible to oxidation and heat. Statistical analysis proves that the method is repeatable, selective, and accurate for the estimation of said drug. Stability indicating of new chemical entities is an important part for the drug development of ambroxol hydrochloride and for its estimation in plasma and other biological fluids; the novel Statistical analysis proves that the method is repeatable and selective for the analysis of ambroxol hydrochloride as bulk drug and in pharmaceutical formulations. The proposed developed HPTLC method can be applied for identification and quantitative determination of ambroxol hydrochloride in bulk drug and dosage forms. This work is to determine the purity of the drug available from the various sources by detecting

  3. Stability of the Photon Indices in Z-source GX 340+0 for Spectral States

    NASA Astrophysics Data System (ADS)

    Seifina, Elena; Titarchuk, Lev; Frontera, Filippo

    2013-03-01

    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) kTe 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 s1 <~ 1 keV coming from the disk (first component Comptb1), and seed photons of temperature T s2 <~ 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 Γcom1 and Γcom2 of the Comptonized components are almost constant, Γcom1 and Γcom2 ~ 2 when kTe 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 Γcom increases during a spectral evolution from the low state to the high state and ultimately saturates at a high mass accretion rate.

  4. Forced degradation of nepafenac: Development and validation of stability indicating UHPLC method.

    PubMed

    Runje, Mislav; Babić, Sandra; Meštrović, Ernest; Nekola, Irena; Dujmić-Vučinić, Željka; Vojčić, Nina

    2016-05-10

    This paper presents stability study of the nonsteroidal anti-inflammatory drug (NSAID) nepafenac. In order to investigate stability of nepafenac, it was subjected to forced degradation under different stress conditions: acid and base hydrolysis, oxidation, humidity, heat and light. A novel stability indicating reverse phase ultra high performance liquid chromatographic (UHPLC) method coupled to ultraviolet detector has been developed to separate nepafenac and all related compounds (2-aminobenzophenone, Cl-thionepafenac, thionepafenac, Cl-nepafenac, hydroxy-nepafenac, and cyclic-nepafenac). Efficient chromatographic separation was achieved on a Waters Acquity BEH C18 stationary phase with a gradient elution. Quantification was carried out at 235 nm at a flow rate of 0.6 mL/min(-1). The resolution between nepafenac and six potential impurities is found to be greater than 2.0. The developed method was validated with respect to specificity, LOD, LOQ, linearity, precision, accuracy and robustness. The r(2) values for nepafenac and six potential impurities were all greater than 0.999. The developed method is capable to detect impurities of nepafenac at a level of 0.005% with respect to test concentration of 1.0mg/mL. Significant degradation is observed in acid, base and oxidative degradation conditions and degradation products (DPs) were identified using mass spectrometry analysis; two of them were found to be a known process related impurities (hydroxy- and cyclic-nepafenac) whereas four degradation products were identified as new degradation impurities. The forced degradation samples were assayed against a qualified reference standard and the mass balance was found to be close to 99.5%. PMID:26871279

  5. Stability-indicating LC method for the estimation of bendamustine hydrochloride and its related impurities.

    PubMed

    Kasa, Srinivasulu; Raja Sekhar Reddy, M; Kadaboina, Raja Sekhar; Murki, Veerender; Mulukutla, Venkata Suryanarayana

    2014-08-01

    A novel, simple, sensitive and stability-indicating high-performance liquid chromatography method was developed and validated for the quantification of impurities (process related and degradants) and the assay determination of Bendamustine hydrochloride. A chromatographic separation of Bendamustine and its impurities was achieved with an Inertsil ODS-2 analytical column, 250 × 4.6 mm, 5 µm, using gradient elution with mobile phase A consisting of a mixture of water and trifluoroacetic acid (1000:1, v/v) and mobile phase B consisting of acetonitrile. The instrumental settings included a flow rate of 1.0 mL/min, column temperature of 27°C and a detector wavelength of 233 nm, using a photodiode array detector. The tailing factor for Bendamustine was 1.10. Bendamustine hydrochloride was exposed to thermal, photolytic, hydrolytic and oxidative stress conditions and the stressed samples were analyzed by the proposed method. Peak homogeneity data of Bendamustine were obtained by using a photodiode array detector in the stressed sample chromatograms, which demonstrated the specificity of the method for estimation in the presence of degradants. The developed method was validated for parameters such as precision, accuracy, linearity, limit of detection, limit of quantification, ruggedness and robustness. The stability tests were also performed on drug substances as per International Conference on Harmonization guidelines. PMID:23825351

  6. Concentration-dependent changes in apparent diffusion coefficients as indicator for colloidal stability of protein solutions.

    PubMed

    Bauer, Katharina Christin; Göbel, Mathias; Schwab, Marie-Luise; Schermeyer, Marie-Therese; Hubbuch, Jürgen

    2016-09-10

    The colloidal stability of a protein solution during downstream processing, formulation, and storage is a key issue for the biopharmaceutical production process. Thus, knowledge about colloidal solution characteristics, such as the tendency to form aggregates or high viscosity, at various processing conditions is of interest. This work correlates changes in the apparent diffusion coefficient as a parameter of protein interactions with observed protein aggregation and dynamic viscosity of the respective protein samples. For this purpose, the diffusion coefficient, the protein phase behavior, and the dynamic viscosity in various systems containing the model proteins α-lactalbumin, lysozyme, and glucose oxidase were studied. Each of these experiments revealed a wide range of variations in protein interactions depending on protein type, protein concentration, pH, and the NaCl concentration. All these variations showed to be mirrored by changes in the apparent diffusion coefficient in the respective samples. Whereas stable samples with relatively low viscosity showed an almost linear dependence, the deviation from the concentration-dependent linearity indicated both an increase in the sample viscosity and probability of protein aggregation. This deviation of the apparent diffusion coefficient from concentration-dependent linearity was independent of protein type and solution properties for this study. Thus, this single parameter shows the potential to act as a prognostic tool for colloidal stability of protein solutions. PMID:27421911

  7. A Stability Indicating HPLC Method for the Determination of Nitisinone in Capsules.

    PubMed

    Souri, Effat; Lahiji, Farnaz R; Nourhashemi, Tannaz; Jalalizadeh, H

    2015-01-01

    In this study a simple and efficient stability-indicating HPLC method with short run time was developed for the determination of nitisinone. The stress degradation of nitisinone was studied in different acidic, basic, oxidative, thermal and photolytic conditions. The chromatographic separation was achieved on a Nova-Pak C18 column using a mixture of 50 mM NaH2PO4 (pH 2.5) and acetonitrile (45:55, v/v) as mobile phase. UV detection was performed at 280 nm. Good linearity was observed over the concentration range of 0.5-50 μg/ml with r(2)>0.999. The within-day and between-day precision values were less than 2%. The proposed method could be used for the determination of nitisinone in the presence of its degradation products and also dosage form excipients for the quality control purposes. PMID:26180282

  8. A Stability Indicating HPLC Method for the Determination of Nitisinone in Capsules

    PubMed Central

    Souri, Effat; Lahiji, Farnaz R.; Nourhashemi, Tannaz; Jalalizadeh, H.

    2015-01-01

    In this study a simple and efficient stability-indicating HPLC method with short run time was developed for the determination of nitisinone. The stress degradation of nitisinone was studied in different acidic, basic, oxidative, thermal and photolytic conditions. The chromatographic separation was achieved on a Nova-Pak C18 column using a mixture of 50 mM NaH2PO4 (pH 2.5) and acetonitrile (45:55, v/v) as mobile phase. UV detection was performed at 280 nm. Good linearity was observed over the concentration range of 0.5-50 μg/ml with r2>0.999. The within-day and between-day precision values were less than 2%. The proposed method could be used for the determination of nitisinone in the presence of its degradation products and also dosage form excipients for the quality control purposes. PMID:26180282

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

    PubMed Central

    2012-01-01

    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 μm) 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 μg mL-1 for moxifloxacin (r2 ≥ 0.998) and 40–160 μg 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

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

    SciTech Connect

    Seifina, Elena

    2013-03-20

    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.

  11. Bioremediation of Contaminated Lake Sediments and Evaluation of Maturity Indicies as Indicators of Compost Stability

    PubMed Central

    Rekha, P.; Suman Raj, D. S.; Aparna, C.; Bindu, V. Hima; Anjaneyulu, Y.

    2005-01-01

    Land contamination is one of the widely addressed problems, which is gaining importance in many developed and developing countries. International efforts are actively envisaged to remediate contaminated sites as a response to adverse health effects. Popular conventional methodologies only transfer the phase of the contaminant involving cost intensive liabilities besides handling risk of the hazardous waste. Physico-chemical methods are effective for specific wastes, but are technically complex and lack public acceptance for land remediation. “Bioremediation”, is one of the emerging low-cost technologies that offer the possibility to destroy various contaminants using natural biological activities. Resultant non -toxic end products due to the microbial activity and insitu applicability of this technology is gaining huge public acceptance. In the present study, composting is demonstrated as a bioremediation methodology for the stabilization of contaminated lake sediments of Hyderabad, A.P, India. Lake sediment contaminated with organics is collected from two stratums – upper (0.25 m) and lower (0.5m) to set up as Pile I (Upper) and Pile II (Lower) in the laboratory. Lime as a pretreatment to the lake sediments is carried out to ensure metal precipitation. The pretreated sediment is then mixed with organic and inorganic fertilizers like cow dung, poultry manure, urea and super phosphate as initial seeding amendments. Bulking agents like sawdust and other micronutrients are provided. Continuous monitoring of process control parameters like pH, moisture content, electrical conductivity, total volatile solids and various forms of nitrogen were carried out during the entire course of the study. The stability of the compost was evaluated by assessing maturity indices like C/N, Cw (water soluble carbon), CNw (Cw/Nw), nitrification index (NH4/NO−3), Cation Exchange Capacity (CEC), germination index, humification ratio, compost mineralization index (ash content

  12. Stability-Indicating HPTLC Determination of Imatinib Mesylate in Bulk Drug and Pharmaceutical Dosage

    NASA Astrophysics Data System (ADS)

    Musmade, P.; Vadera, N.; Subramanian, G.

    A simple, selective, precise and stability-indicating high-performance thin-layer chromatographic method of analysis of imatinib mesylate both as a bulk drug and in formulations was developed and validated. The method employed HPTLC aluminum plates precoated with silica gel 60F-254 as the stationary phase. The solvent system consisted of chloroform:methanol (6:4, v/v). The system was found to give compact spot for imatinib mesylate (R f value of 0.53 ± 0.02). Densitometric analysis of imatinib mesylate was carried out in the absorbance mode at 276 nm. The linear regression analysis data for the calibration plots showed good linear relationship with r 2 = 0.9966 ± 0.0013 with respect to peak area in the concentration range 100-1,000 ng per spot. The mean value ± SD of slope and intercept were 164.85 ± 0.72 and 1168.3 ± 8.26, respectively, with respect to peak area. The method was validated for precision, recovery, and robustness. The limits of detection and quantitation were 10 and 30 ng per spot, respectively. Imatinib mesylate was subjected to acid and alkali hydrolysis, and oxidation and thermal degradation. The drug undergoes degradation under acidic, basic, oxidation, and heat conditions. This indicates that the drug is susceptible to acid, base hydrolysis, oxidation, and heat. Statistical analysis proves that the method is repeatable, selective, and accurate for the estimation of the said drug. The proposed developed HPTLC method can be applied for identification and quantitative determination of imatinib mesylate in bulk drug and dosage forms.

  13. Stability-indicating HPLC Method for Simultaneous Determination of Montelukast and Fexofenadine Hydrochloride

    PubMed Central

    Pankhaniya, Mona; Patel, Parula; Shah, J. S.

    2013-01-01

    A simple, specific, accurate, and stability-indicating reversed-phase high-performance liquid chromatographic method was developed for the simultaneous determination of montelukast and fexofenadine hydrochloride, using a Lichrospher® 100, RP-18e column and a mobile phase composed of methanol:0.1% o-phosphoric acid (90:10 v/v), pH 6.8. The retention times of montelukast and fexofenadine hydrochloride were found to be 10.16 and 12.03 min, respectively. Linearity was established for montelukast and fexofenadine hydrochloride in the range of 2-10 μg/ml and 24-120 μg/ml, respectively. The percentage recoveries of montelukast and fexofenadine hydrochloride were found to be in the range of 99.09 and 99.81%, respectively. Both the drugs were subjected to acid and base hydrolysis, oxidation, photolytic, and thermal degradation conditions. The degradation products of montelukast and fexofenadine hydrochloride were well resolved from the pure drug with significant differences in their retention time values. This method can be successfully employed for simultaneous quantitative analysis of montelukast and fexofenadine hydrochloride in bulk drugs and formulations. PMID:24082344

  14. Stability-indicating spectrofluorometric method for the determination of some cephalosporin drugs via their degradation products.

    PubMed

    Mostafa, Nadia M; Abdel-Fattah, Laila; Weshahy, Soheir A; Hassan, Nagiba Y; Boltia, Shereen A

    2015-01-01

    A stability-indicating spectrofluorometric method was investigated for the determination of three cephalosporin drugs, namely, cefpodoxime proxetil (CPD), cefixime trihydrate (CFX), and cefepime hydrochloride (CPM), via their acid and alkali degradation products. The three drugs were determined via their acid degradation at 432, 422, and 435 nm using an excitation wavelength of 310, 330, and 307 nm for CPD, CFX, and CPM determination, respectively, and via their alkali degradation at 407, 411, and 405 nm using an excitation wavelength of 310, 305, and 297 nm for CPD, CFX, and CPM determination, respectively. Linearity was achieved in the ranges of 0.35-3.50, 0.4-4.0, and 0.3-3.0 μg/mL for the acid degradation products of CPD, CFX, and CPM, respectively, and in ranges of 0.05-0.5, 0.1-1.0, and 0.08-0.80 μg/mL for the alkali degradation products of CPD, CFX, and CPM, respectively. The method was validated for various parameters according to International Conference on Harmonization guidelines. The method was successfully applied for the determination of these cephalosporin drugs in pharmaceutical dosage forms with good accuracy and precision. The results obtained by the proposed spectrofluorometric method were compared with good agreement to the official HPLC method. PMID:25905742

  15. Smart stability-indicating spectrophotometric methods for determination of binary mixtures without prior separation.

    PubMed

    El-Bardicy, Mohammad G; Lotfy, Hayam M; El-Sayed, Mohammad A; El-Tarras, Mohammad F

    2008-01-01

    Ratio subtraction and isosbestic point methods are 2 innovating spectrophotometric methods used to determine vincamine in the presence of its acid degradation product and a mixture of cinnarizine (CN) and nicergoline (NIC). Linear correlations were obtained in the concentration range from 8-40 microg/mL for vincamine (I), 6-22 microg/mL for CN (II), and 6-36 microg/mL for NIC (III), with mean accuracies 99.72 +/- 0.917% for I, 99.91 +/- 0.703% for II, and 99.58 +/- 0.847 and 99.83 +/- 1.039% for III. The ratio subtraction method was utilized for the analysis of laboratory-prepared mixtures containing different ratios of vincamine and its degradation product, and it was valid in the presence of up to 80% degradation product. CN and NIC in synthetic mixtures were analyzed by the 2 proposed methods with the total content of the mixture determined at their respective isosbestic points of 270.2 and 235.8 nm, and the content of CN was determined by the ratio subtraction method. The proposed method was validated and found to be suitable as a stability-indicating assay method for vincamine in pharmaceutical formulations. The standard addition technique was applied to validate the results and to ensure the specificity of the proposed methods. PMID:18476341

  16. Stability-indicating methods for determination of vincamine in presence of its degradation product.

    PubMed

    Shehata, Mostafa A M; El Sayed, Mohammad A; El Tarras, Mohammad F; El Bardicy, Mohammad G

    2005-06-01

    Three different stability indicating assay methods are developed and validated for determination of vincamine in the presence of its degradation product (vincaminic acid). The first method is based on the derivative ratio zero crossing spectrophotometric technique using 0.1 N hydrochloric acid as a solvent. In the second method, measurements are based on spectro-densitometric technique using high performance thin-layer chromatography (HPTLC) plates with a developing system consisting of methanol-chloroform-ethyl acetate (2:1:1, v/v/v). The third method depends on high-performance liquid chromatography (HPLC). Separation of vincamine from vincaminic acid using Lichrocart RP-18 column (250 mm x 4.6 mm i.d.) with a mobile phase consisting of acetonitrile-ammonium carbonate (0.01 M) (7:3, v/v) is achieved. The methods showed high sensitivity with good linearity over the concentration ranges of 12 to 48 microg ml-1, 3 to 17 microg/spot, and 2 to 20 microg ml-1 for derivative spectrophotometry, spectro-densitometry and HPLC methods, respectively. The developed methods were successfully applied to the analysis of pharmaceutical formulations containing vincamine with excellent recoveries. PMID:15907622

  17. A Stability Indicating HPLC Method for the Determination of Fluvoxamine in Pharmaceutical Dosage Forms

    PubMed Central

    Souri, Effat; Donyayi, Hassan; khaniha, Reza Ahmad; Barazandeh Tehrani, Maliheh

    2015-01-01

    Fluvoxamine maleate is a selective serotonin reuptake inhibitor, which is used for the treatment of different types of depressive disorders. In the present study, a stability indicating HPLC method was developed and validated for the determination of fluvoxamine maleate. The chromatographic separation was carried out using a Nova-Pak CN column and a mixture of K2HPO4 50 mM (pH 7.0) and acetonitrile (60: 40, v/v) as the mobile phase. Target compounds were detected using a UV detector set at 235 nm. The developed method was linear over the concentration range of 1-80 μg/ml with acceptable precision (CV values < 2.0%) and accuracy (error values < 1.6%). The degradation studies showed that fluvoxamine maleate is relatively unstable under acidic, basic and oxidative conditions and also when exposed to UV radiation. On the other hand, the bulk powder of fluvoxamine maleate was relatively stable when exposed to visible light or heat. The proposed method was successfully applied for the determination of active ingredient of fluvoxamine dosage form without any interference from tablet excipients. PMID:26664372

  18. A Stability Indicating HPLC Method for the Determination of Fluvoxamine in Pharmaceutical Dosage Forms.

    PubMed

    Souri, Effat; Donyayi, Hassan; Khaniha, Reza Ahmad; Barazandeh Tehrani, Maliheh

    2015-01-01

    Fluvoxamine maleate is a selective serotonin reuptake inhibitor, which is used for the treatment of different types of depressive disorders. In the present study, a stability indicating HPLC method was developed and validated for the determination of fluvoxamine maleate. The chromatographic separation was carried out using a Nova-Pak CN column and a mixture of K2HPO4 50 mM (pH 7.0) and acetonitrile (60: 40, v/v) as the mobile phase. Target compounds were detected using a UV detector set at 235 nm. The developed method was linear over the concentration range of 1-80 μg/ml with acceptable precision (CV values < 2.0%) and accuracy (error values < 1.6%). The degradation studies showed that fluvoxamine maleate is relatively unstable under acidic, basic and oxidative conditions and also when exposed to UV radiation. On the other hand, the bulk powder of fluvoxamine maleate was relatively stable when exposed to visible light or heat. The proposed method was successfully applied for the determination of active ingredient of fluvoxamine dosage form without any interference from tablet excipients. PMID:26664372

  19. Spectrofluorimetric methods of stability-indicating assay of certain drugs affecting the cardiovascular system

    NASA Astrophysics Data System (ADS)

    Moussa, B. A.; Mohamed, M. F.; Youssef, N. F.

    2011-01-01

    Two stability-indicating spectrofluorimetric methods have been developed for the determination of ezetimibe and olmesartan medoxomil, drugs affecting the cardiovascular system, and validated in the presence of their degradation products. The first method, for ezetimibe, is based on an oxidative coupling reaction of ezetimibe with 3-methylbenzothiazolin-2-one hydrazone hydrochloride in the presence of cerium (IV) ammonium sulfate in an acidic medium. The quenching effect of ezetimibe on the fluorescence of excess cerous ions is measured at the emission wavelength, λem, of 345 nm with the excitation wavelength, λex, of 296 nm. Factors affecting the reaction were carefully studied and optimized. The second method, for olmesartan medoxomil, is based on measuring the native fluorescence intensity of olmesartan medoxomil in methanol at λem = 360 nm with λex = 286 nm. Regression plots revealed good linear relationships in the assay limits of 10-120 and 8-112 g/ml for ezetimibe and olmesartan medoxomil, respectively. The validity of the methods was assessed according to the United States Pharmacopeya guidelines. Statistical analysis of the results exposed good Student's t-test and F-ratio values. The introduced methods were successfully applied to the analysis of ezetimibe and olmesartan medoxomil in drug substances and drug products as well as in the presence of their degradation products.

  20. Stability-indicating HPLC method for the determination of impurities in meprobamate with refractive index detection.

    PubMed

    Karthikeyan, K; Balaji, T S; Shanmugasundaram, P; Chandrasekara Pillai, K

    2010-03-01

    The purpose of this study is to develop and validate a simple, sensitive, and robust high-performance liquid chromagraphic (HPLC) method for the determination of impurities ca. 2-methyl-2-propyl-1,3-propane diol (MP0) and 2-hydroxymethyl-2-methyl pentyl carbamate (MP1) in meprobamate (MEP) drug substance with refractive index (RI) detection. This method utilizes a Zorbax Eclipse XDB C(18) HPLC column, a mobile phase of 80:20 (v/v) 10 mM KH(2)PO(4),-acetonitrile, respectively. The stability-indicating capability of the method has been established by performing stress studies under acidic, basic, oxidation, light, humidity, and thermal conditions. The major degradation products of acid and base hydrolysis are identified as MP0 and MP1. The recovery data obtained for impurities are between 96.0-109.8%. The detection and quantitation limits of this method ranges from 0.009 to 0.017 mg/mL and 0.029 to 0.055 mg/mL, respectively. The relative standard deviation (RSD) for the area at QL is less than 6.1%. Good linearity (r(2) > 0.99) and precision (RSD < 2.2%) have been obtained for MEP, MP0, and MP1. This method has been applied successfully to determine the content of impurities in MEP bulk drug. PMID:20223088

  1. A stability-indicating HPLC method for simultaneous determination of morphine and naltrexone.

    PubMed

    Jafari-Nodoushan, Milad; Barzin, Jalal; Mobedi, Hamid

    2016-02-01

    This study developed a stability-indicating reversed-phase HPLC method for the simultaneous determination of morphine sulfate and naltrexone hydrochloride content in bulk, Solid dosage forms and in-vitro dissolution samples to support product development and quality control efforts. Chromatographic separation of the pharmaceutical compound was achieved on a perfectSil™ MZ C18 column (250×4.6mm, 5μm) with an isocratic mobile phase composed of a mixture of acetate buffer (10mM, pH 4, containing 0.1% of 1-heptanesulfonic acid sodium salt) and acetonitrile with 80/20 at a flow rate of 1.5mlmin(-1). Both analytes were quantified using a photodiode array detector set at a wavelength of 280nm and column temperature was set to 30°C. naltrexone, morphine and a mixture of the two were subjected to thermal, peroxide, acid, base and photolytic degradation and their peak homogeneity was obtained using a photodiode array detector, demonstrating the specificity of method. These pharmaceuticals were spiked in biological fluid to examine method selectivity. The method was validated for system suitability, linearity, accuracy, precision, detection and quantification limits and robustness and was found it is acceptable in range of 2-250μgml(-1) for morphine and 4-100μgml(-1) for naltrexone. PMID:26773883

  2. Stability-indicating HPLC method for the determination of the stability of oxytocin parenteral solutions prepared in polyolefin bags.

    PubMed

    Kaushal, G; Sayre, B E; Prettyman, T

    2012-02-01

    Oxytocin is very commonly used in clinical settings and is a nonapeptide hormone that stimulates the contraction of uterine smooth muscles. In this study the stability of extemporaneously compounded oxytocin solutions was investigated in polyolefin bags. The sterile preparations of oxytocin were compounded to the strength of 0.02 U/mL in accordance with United States Pharmacopeia (USP) <797> standards. In order to carry out the stability testing of these parenteral products, the solutions were stored under three different temperature conditions of -20°C (frozen), 2-6°C (refrigerated), and 22-25°C (room temperature). Three solutions from each temperature were withdrawn and were assessed for stability on days 0, 7, 15, 21, and 30 as per the USP guidelines. The assay of oxytocin was examined by an HPLC method at each time point. No precipitation, cloudiness or color change was observed during this study at all temperatures. The assay content by HPLC revealed that oxytocin retains greater than at least 90% of the initial concentrations for 21 days. There was no significant change in pH and absorbance values for 21 days under all the conditions of storage. Oxytocin parenteral solutions in the final concentration of 0.02 U/mL and diluted in normal saline are stable for at least 30 days under frozen and refrigerated conditions for 30 days. At the room temperature, the oxytocin solutions were stable for at least 21 days. The stability analysis results show that the shelf-life of 21 days observed in this study was far better than their recommended expiration dates. PMID:22460429

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

    PubMed

    Doomkaew, Athiporn; Prutthiwanasan, Brompoj; Suntornsuk, Leena

    2015-01-01

    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 5 min using 10mM phosphate buffer (pH 7.0) containing 15 mM sodium dodecyl sulfate on a fused-silica capillary with an effective length of 40 cm and an inner diameter of 50 μm, injection at 50 mbar for 5s, temperature of 25°C, applied voltage of 20 kV and photodiode array detection at 225 nm. The method showed good linearity (r(2)>0.99, in the ranges of 128-192, 20-60 and 10-50 μg/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 μg/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

  4. Improving The Retrieval Of Atmospheric Stability Indices By Combining Ground-based And Satellite Remote Sensing

    NASA Astrophysics Data System (ADS)

    Loehnert, U.; Ebell, K.; Orlandi, E.

    2015-12-01

    A new generation of high-resolution (~1km) weather forecast models now becoming operational over Europe promises to revolutionize predictions of severe weather, specifically by explicitly resolving convection. For this, a dense observing network is required, focusing especially on the lowest few km of the atmosphere, so that forecast models have the most realistic state of the atmosphere for initialization, continuous assimilation and verification. In this context, the current European COST action TOPROF (ES1303) deals with operational networking of three existing but so far under-exploited, ground-based remote sensing instruments throughout Europe: i) Several hundreds of ceilometers, ii) more than 20 Doppler lidars, and iii) About 30 microwave profilers (MWP) giving profiles of temperature and humidity in the lowest few km every 10 minutes. Specifically, MWP are highly suited for continuously monitoring the temporal development of atmospheric stability (i.e. Cimini et al. 2015, AMT) before the initiation of deep convection. However, the vertical resolution of MWP temperature profiles is best in the lowest kilometer above the surface, decreasing rapidly with increasing height. In addition, humidity profile retrievals typically cannot be resolved with more than two degrees of freedom for signal, resulting in a rather poor vertical resolution throughout the troposphere. Typical stability indices (i.e. K-index, Lifted Index, Showalter Index, CAPE,..) rely on temperature and humidity values not only in the region of the boundary layer (850 hPa) but also at 700 hPa, 500 hPa, in between these levels or even higher above. In this study, for clear sky cases, satellite remote sensing (i.e. SEVIRI radiances from the geostationary METEOSAT ) is used to complement the ground-based MWP information. The theoretical basis of the combined retrieval is highlighted, error reductions resulting from the sensor synergy are discussed and applications to real data are shown. The study

  5. Kinetics of α-Globin Binding to α-Hemoglobin Stabilizing Protein (AHSP) Indicate Preferential Stabilization of Hemichrome Folding Intermediate*

    PubMed Central

    Mollan, Todd L.; Khandros, Eugene; Weiss, Mitchell J.; Olson, John S.

    2012-01-01

    Human α-hemoglobin stabilizing protein (AHSP) is a conserved mammalian erythroid protein that facilitates the production of Hemoglobin A by stabilizing free α-globin. AHSP rapidly binds to ferrous α with association (k′AHSP) and dissociation (kAHSP) rate constants of ≈10 μm−1 s−1 and 0.2 s−1, respectively, at pH 7.4 at 22 °C. A small slow phase was observed when AHSP binds to excess ferrous αCO. This slow phase appears to be due to cis to trans prolyl isomerization of the Asp29-Pro30 peptide bond in wild-type AHSP because it was absent when αCO was mixed with P30A and P30W AHSP, which are fixed in the trans conformation. This slow phase was also absent when met(Fe3+)-α reacted with wild-type AHSP, suggesting that met-α is capable of rapidly binding to either Pro30 conformer. Both wild-type and Pro30-substituted AHSPs drive the formation of a met-α hemichrome conformation following binding to either met- or oxy(Fe2+)-α. The dissociation rate of the met-α·AHSP complex (kAHSP ≈ 0.002 s−1) is ∼100-fold slower than that for ferrous α·AHSP complexes, resulting in a much higher affinity of AHSP for met-α. Thus, in vivo, AHSP acts as a molecular chaperone by rapidly binding and stabilizing met-α hemichrome folding intermediates. The low rate of met-α dissociation also allows AHSP to have a quality control function by kinetically trapping ferric α and preventing its incorporation into less stable mixed valence Hemoglobin A tetramers. Reduction of AHSP-bound met-α allows more rapid release to β subunits to form stable fully, reduced hemoglobin dimers and tetramers. PMID:22298770

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

    PubMed Central

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

    2011-01-01

    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 μl. 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

  7. Stability-Indicating HPTLC Method for Studying Stress Degradation Behavior of Sulbutiamine HCl.

    PubMed

    Farid, Nehal F; Abdelwahab, Nada S

    2016-04-01

    Sulbutiamine (SUL) is an ester of thiazides with neurotropic action. A new stability indicating HPTLC method has been developed and validated for the determination of SUL in the presence of different degradation products. The drug was subjected to different stress conditions following ICH strategy such as hydrolytic degradation (neutral, alkaline and acidic hydrolysis), oxidation, photodegradation and dry heat degradation. The drug demonstrated degradation under all decomposition conditions except neutral hydrolysis and dry heat, where the drug was completely degraded with 0.1 N NaOH, 1 N HCl and 30% H2O2 while it was partially degradaed by 0.1 N HCl, 3% H2O2 and UV light. Structure elucidation of the resulting degradation products was performed using ESI-Q-MS-MS. A well-defined peak for SUL was obtained at Rf = 0.46 and was completely separated from all obtained degradation products. Chromatographic separation was carried out on HPTLC aluminum plates precoated with silica gel 60 F254 using acetone-methylene chloride-ammonia buffer (pH 8.5 ± 0.2) (7:3:0.5, v/v) as a developing system. Densitometric scanning of the separated peaks was performed at 254 nm. System suitability testing parameters were calculated to ascertain the quality performance of the developed method. The method was validated with respect to USP guidelines regarding accuracy, precision, specificity, robustness and ruggedness. Good correlation coefficients were achieved in the range of 0.4-5.0 µg/band, and the limit of detection and limit of quantitation were found to be 0.11 and 0.33 µg/band, respectively. The utility of the suggested method was verified by application to Arcalion forte® tablets where no interference from additives was found. PMID:26759487

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

    PubMed

    Porel, A; Haty, Sanjukta; Kundu, A

    2011-01-01

    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 μl. The calibration graphs plotted with five concentrations of each component were linear with a regression coefficient R(2) >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

  9. Reduction of indicator and pathogenic microorganisms in pig manure through fly ash and lime addition during alkaline stabilization.

    PubMed

    Wong, Jonathan W C; Selvam, Ammaiyappan

    2009-09-30

    A pilot scale study was conducted to evaluate the effect of lime and alkaline coal fly ash (CFA) on the reduction of pathogens in pig manure during alkaline stabilization and suppression of re-growth during post-stabilization incubation. Pig manure was mixed with CFA at 25%, 33% and 50%, and a control without fly ash was maintained. To these manure-ash mixtures, lime was added at the rate of 2% or 4% and incubated for 8 days. During the incubation, the population of Salmonella, fecal coliforms, Escherichia coli, fecal Streptococcus and total bacteria were enumerated. After the alkaline stabilization process, the mixtures were incubated under green house condition to evaluate the re-growth of pathogens. During the 8-day alkaline stabilization, Salmonella, fecal coliforms, E. coli and fecal Streptococcus were completely devitalized in manure-ash-lime mixtures, whereas in the control, incubation reduced the pathogen and total bacterial population by 2-3 logs. Fecal streptococcus was destructed within 4 days of alkaline stabilization, whereas other pathogens needed 8 days for their destruction. During the incubation in green house, an increase in the population of the pathogens and total bacteria was observed. Results indicate that alkaline stabilization of pig manure with lime at 4% and CFA at 50% is effective in devitalizing the pathogens and reducing the post-stabilization re-growth. PMID:19442442

  10. GO annotation in InterPro: why stability does not indicate accuracy in a sea of changing annotations

    PubMed Central

    Sangrador-Vegas, Amaia; Mitchell, Alex L.; Chang, Hsin-Yu; Yong, Siew-Yit; Finn, Robert D.

    2016-01-01

    The removal of annotation from biological databases is often perceived as an indicator of erroneous annotation. As a corollary, annotation stability is considered to be a measure of reliability. However, diverse data-driven events can affect the stability of annotations in both primary protein sequence databases and the protein family databases that are built upon the sequence databases and used to help annotate them. Here, we describe some of these events and their consequences for the InterPro database, and demonstrate that annotation removal or reassignment is not always linked to incorrect annotation by the curator. Database URL: http://www.ebi.ac.uk/interpro PMID:26994912

  11. Identification and quantification of furanocoumarins in stem bark and wood of eight Algerian varieties of Ficus carica by RP-HPLC-DAD and RP-HPLC-DAD-MS.

    PubMed

    Rouaiguia-Bouakkaz, Samia; Amira-Guebailia, Habiba; Rivière, Céline; Delaunay, Jean-Claude; Waffo-Téguo, Pierre; Mérillon, Jean-Michel

    2013-04-01

    Furanocoumarins are the major phytoalexins of Ficus carica and are effective natural drug candidates for treatment of several types of cancer and skin disease. The objectives of this study were to analyze and quantify linear furanocoumarins, mainly psoralen and bergapten, in wood and bark of stems from eight Algerian varieties of fig and to establish the differences in the content of these metabolites in the eight local samples. Psoralen and bergapten contents in the stem bark and wood (in microg/g DW) varied respectively from 146.6 to 1110.3 and from 395.7 to 1671.8 for psoralen, and from 114.3 to 524.0 and from 144.2 to 718.6 for bergapten. This study fills a gap in our knowledge of furanocoumarin distribution in different parts of the fig tree. Psoralen and bergapten concentrations were higher in the wood than in the stem bark. Most of the dark fruited fig trees produce these two coumarins more than the green ones. PMID:23738460

  12. Stability and maturity of biowaste composts derived by small municipalities: Correlation among physical, chemical and biological indices.

    PubMed

    Oviedo-Ocaña, E R; Torres-Lozada, P; Marmolejo-Rebellon, L F; Hoyos, L V; Gonzales, S; Barrena, R; Komilis, D; Sanchez, A

    2015-10-01

    Stability and maturity are important criteria to guarantee the quality of a compost that is applied to agriculture or used as amendment in degraded soils. Although different techniques exist to evaluate stability and maturity, the application of laboratory tests in municipalities in developing countries can be limited due to cost and application complexities. In the composting facilities of such places, some classical low cost on-site tests to monitor the composting process are usually implemented; however, such tests do not necessarily clearly identify conditions of stability and maturity. In this article, we have applied and compared results of stability and maturity tests that can be easily employed on site (i.e. temperature, pH, moisture, electrical conductivity [EC], odor and color), and of tests that require more complex laboratory techniques (volatile solids, C/N ratio, self-heating, respirometric index, germination index [GI]). The evaluation of the above was performed in the field scale using 2 piles of biowaste applied compost. The monitoring period was from day 70 to day 190 of the process. Results showed that the low-cost tests traditionally employed to monitor the composting process on-site, such as temperature, color and moisture, do not provide consistent determinations with the more complex laboratory tests used to assess stability (e.g. respiration index, self-heating, volatile solids). In the case of maturity tests (GI, pH, EC), both the on-site tests (pH, EC) and the laboratory test (GI) provided consistent results. Although, stability was indicated for most of the samples, the maturity tests indicated that products were consistently immature. Thus, a stable product is not necessarily mature. Conclusively, the decision on the quality of the compost in the installations located in developing countries requires the simultaneous use of a combination of tests that are performed both in the laboratory and on-site. PMID:26216503

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

    SciTech Connect

    Koubsky, T.; Kalvoda, L.; Drab, M.

    2013-07-01

    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)

  14. Survey of Wastewater Indicators and Human Pathogen Genomes in Biosolids Produced by Class A and Class B Stabilization Treatments ▿

    PubMed Central

    Viau, Emily; Peccia, Jordan

    2009-01-01

    Accurate modeling of the infectious aerosol risk associated with the land application of biosolids requires an in-depth knowledge of the magnitudes and changes in pathogen concentrations for a variety of class A and class B stabilization methods. The following survey used quantitative PCR (qPCR) and culture assays to detect environmentally resistant bacterial and viral pathogens and biosolid indicator organisms for 36 biosolid grab samples. Biosolids were collected from 14 U.S. states and included 16 class B mesophilic anaerobic digestion (MAD) samples and 20 class A biosolid samples from temperature-phased anaerobic digestion (TPAD), MAD plus composting (COM), and MAD plus heat pelletization processes. The indicator concentrations of fecal coliforms and male-specific coliphages as well as pathogen genome concentrations for human adenovirus species, Legionella pneumophila, Staphylococcus aureus, and Clostridium difficile were significantly lower in the class A samples, and a multivariate analysis of variance ranked the stabilization processes from the lowest pathogen/indicator load to the highest as (i) class A COM, (ii) class A TPAD, and (iii) class B MAD. Human adenovirus genomes were found in 88% of the class B samples and 70 to 100% of the class A samples. L. pneumophila, S. aureus, and C. difficile genomes were detected at the qPCR assay detection limits in 19 to 50% of the class B and class A anaerobic digestion samples, while L. pneumophila was detected in 50% of the class A compost samples. When considering all the stabilization methods, both the fecal coliform and the male-specific coliphage concentrations show a significant linear correlation with the pathogen genome concentrations. This survey provides the necessary pathogen concentrations to add to biosolid aerosol risk and pathogen exposure analyses and clarifies the effectiveness of class A stabilization methods with the pathogen and indicator loads in biosolids. PMID:18997022

  15. Removal of bacterial and viral faecal indicator organisms in a waste stabilization pond system in Choconta, Cundinamarca (Colombia).

    PubMed

    Campos, C; Guerrero, A; Cárdenas, M

    2002-01-01

    A major objective for domestic wastewater treatment using waste stabilization pond systems is the removal of pathogenic microorganisms. Traditional evaluation parameters for faecal contamination are the total and faecal coliforms. However, epidemiological studies, environmental resistance and the behaviour in the treatment systems, show that viruses are an important disease agent and even more resistant to disinfection than bacteria. Therefore, it is important to introduce viruses as a faecal indicator and to compare them with the traditional bacterial indicators. A waste stabilization pond system was evaluated in the municipality of Chocontá, Cundinamarca (Colombia), for the removal of faecal indicators (such as Escherichia coli, Streptococcus faecalis, Clostridium perfringens) and viruses like F+, somatic and Bacteroides fragilis phages. The system includes two facultative ponds in series with a flow of 1555 m3/day. Samples were collected at the entrance of the system, in the two ponds and from the final effluent. Results show a decrease between 0.3 and 4.7 logarithmic units in the bacterial indicators and between 1 and 4.6 logarithmic units with viral indicators. PMID:11833732

  16. Stability-Indicating HPLC-UV Method for Vitamin D3 Determination in Solutions, Nutritional Supplements and Pharmaceuticals.

    PubMed

    Temova, Žane; Roškar, Robert

    2016-08-01

    A simple and fast high-performance liquid chromatography method with UV detection for determination of vitamin D3 in stability studies as well as in solutions, nutritional supplements and pharmaceuticals was developed. Successful separation of vitamin D3 from its degradation products was achieved on a Gemini C18 100 × 3.0 mm column using a mixture of acetonitrile and water (99:1, v/v) as а mobile phase. The method was successfully validated according to the ICH guidelines. The described reversed-phase HPLC method is favorable compared with other published HPLC-UV methods because of its stability-indicating nature, short run time (3.3 min) and wide analytical range with outstanding linearity, accuracy and precision. The method was further applied for quantification of vitamin D3 in selected liquid and solid nutritional supplements and prescription medicines, confirming its suitability for routine analysis. Degradation products, formed under stress conditions (hydrolysis, oxidation, photolysis and thermal degradation), were additionally elucidated by suitable equipment (LC-DAD-MS) to confirm the stability-indicating nature of the developed method. PMID:27048642

  17. Characterization of mandarin (Citrus deliciosa Ten.) essential oil. Determination of volatiles, non-volatiles, physico-chemical indices and enantiomeric ratios.

    PubMed

    Bonaccorsi, Ivana; Dugo, Paola; Trozzi, Alessandra; Cotroneo, Antonella; Dugo, Giovanni

    2009-11-01

    An investigation of 27 samples of mandarin essential oils (Citrus deliciosa Tenore), industrially produced in Sicily during the 2007-2008 season, was performed to determine the composition of the volatile fraction by GC/FID and GC/MS-LRI, the enantiomeric distribution of some monoterpene hydrocarbons and linalol by Es-GC, the non-volatile oxygen heterocyclic components by RP-HPLC/PDA and the physico-chemical indices (relative density, refractive index, optical rotation, residue on evaporation, and UV spectroscopic CD value). This study up-dates the information available in the literature on Sicilian mandarin (C. deliciosa Ten.) essential oils, and provides information on the composition and quality parameters for the evaluation of this product. PMID:19967998

  18. Development and validation of a stability indicating UPLC method for determination of ticlopidine hydrochloride in its tablet formulation

    PubMed Central

    Ram, Vijay; Kher, Govind; Dubal, Kapil; Dodiya, Bhavesh; Joshi, Hitendra

    2011-01-01

    The objective of the current study was the development of a simple, precise and accurate isocratic reversed-phase stability indicating Ultra Performance Liquid Chromatography [UPLC] assay method and validated for determination of ticlopidine hydrochloride in solid pharmaceutical dosage forms. Isocratic separation was achieved on a Zorbax SB-C18 (50 mm × 4.6 mm, 1.8 μm) column using mobile phase of methanol–0.01 M ammonium acetate buffer, pH 5.0 (80:20, v/v) at a flow rate of 0.8 ml min−1, the injection volume was 4.0 μl and the detection was carried out at 235 nm by using photo-diode array detector. The drug was subjected to oxidation, hydrolysis, photolysis and heat to apply stress condition. The method was validated for specificity, linearity, precision, accuracy, robustness and solution stability. The method was linear in the drug concentration range of 62.5–375 μg ml−1 with a correlation coefficient of 0.9999. The precision (relative standard deviation – RSD) of six samples was 1.31% for repeatability and the intermediate precision [RSD] among six-sample preparation was 0.77%. The accuracy (recovery) was between 98.80% and 101.50%. Degradation products produced as a result of stress studies did not interfere with detection of ticlopidine hydrochloride and the assay can thus be considered stability indicating. PMID:23960754

  19. Simultaneous, stability indicating, HPLC-DAD determination of guaifenesin and methyl and propyl-parabens in cough syrup.

    PubMed

    Grosa, Giorgio; Del Grosso, Erika; Russo, Roberta; Allegrone, Gianna

    2006-06-01

    A stability indicating high performance liquid chromatography procedure has been developed for the simultaneous determination of guaifenesin (GUA), methyl p-hydroxybenzoate (MHB) and propyl p-hydroxybenzoate (PHB) in a commercial cough syrup dosage form. The method was specific and stability indicating as chromatographic conditions were selected to provide adequate separation of GUA, MHB and PHB from the putative degradation products guaiacol (GUAI) and p-hydroxybenzoic acid (HBA) as well as from excipients. The isocratic separation and quantitation were achieved within 17 min on a 150-mm column with an ether-linked phenyl stationary phase and a hydrophilic endcapping. The mobile phase was constituted of eluant A: aqueous phosphate buffer (pH 3.0, 10 mM)/acetonitrile 25/75 (v/v) and eluant B:methanol; the A:B ratio was 85:15 (v/v) with a flow rate 1 ml min-1 and detection of analytes at 254 and 276 nm. The method showed good linearity for the GUA-MHB-PHB mixture in the 95-285, 4-12, and 1-3 microg ml-1 ranges, respectively, being all the square of the correlation coefficients greater than 0.999. The interday R.S.D.s were 1.17, 1.14, and 0.91%, for GUA, MHB, and PHP, respectively. The method demonstrated also to be accurate; indeed the average recoveries, at 100% of the target assay concentration, were 100.5, 100.3, and 100.7% with relative standard deviations of 0.8, 0.7, and 0.4% for GUA, MHB, and PHB, respectively, from laboratory prepared samples. The applicability of the method was evaluated in commercial dosage form analysis as well as in stability studies. PMID:16497471

  20. A validated stability-indicating TLC-densitometric method for the determination of stanozolol in pharmaceutical formulations

    PubMed Central

    2013-01-01

    Background Stanozolol is a synthetic derivative of dihydrotestosterone (DHT), and one of the frequently detected anabolic steroids in doping analysis. The current work describes the development and validation of the stability-indicating TLC-densitometric method for sensitive and specific estimation of stanozolol even its degradation product being there. Precoated silica gel TLC aluminium plates were utilized as the stationary phase and the eluent comprised of petroleum ether: acetone (6:4, v/v). Densitometric analysis of stanozolol was achieved at λmax 750 nm in the absorbance mode after staining with phosphomolybdic acid (PMA). Stress degradation of stanozolol was carried out under various reaction conditions including acid, base and neutral hydrolysis, wet and dry heating treatment, oxidation, and photo-degradation. Resulted stress samples and pharmaceutical products were analyzed with the developed TLC method. Results This system showed a compact spot for stanozolol at Rf value of 0.46 ± 0.02. The data of linear regression analysis indicated a good linear relationship over the range of 200–1200 ng/spot concentrations. The method was validated for robustness, precision and recovery. The LOD and LOQ were 1.6 and 5.1 ng/spot, respectively. Under various stressed conditions, stanozolol showed degradation only under acidic hydrolysis. Peak of a degraded product was well resolved from the stanazolol with reasonably different Rf value and identified as 17, 17-dimethyl-l8-nor-5α-androst-13(14)-eno [3,2c] pyrazole through 1D- and 2D-NMR spectroscopic techniques and ESI-QqTOF-MS/MS analysis. Conclusion Result reflected that the stanozolol is majorly affected by the acidic condition. Statistical analysis indicated the application of the developed stability-indicating TLC-densitometric method for routine analysis of stanozolol in the presence of its degradation product. PMID:23978309

  1. ICH guidance in practice: establishment of inherent stability of secnidazole and development of a validated stability-indicating high-performance liquid chromatographic assay method.

    PubMed

    Bakshi, Monika; Singh, Saranjit

    2004-11-19

    The degradation behaviour of secnidazole was investigated under different stress degradation (hydrolytic, oxidative, photolytic and thermal) conditions recommended by International Conference on Harmonisation (ICH) using HPLC and LC-MS. A stability-indicating HPLC method was developed that could separate drug from degradation products formed under various conditions. Secnidazole was found to degrade significantly in alkaline conditions, oxidative stress, and also in the presence of light. Mild degradation of the drug occurred in acidic and neutral conditions. The drug was stable to dry heat. Resolution of drug and the degradation products formed under different stress studies were successfully achieved on a C-18 column utilizing water-methanol in the ratio of 85:15 and at the detection wavelength of 310 nm. The method was validated with respect to linearity, precision (including intermediate precision), accuracy, selectivity and specificity. PMID:15533669

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

    PubMed Central

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

    2011-01-01

    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 μm) 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 μg/ml (r2=0.9995) for atenolol and 8-32 μg/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

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

    PubMed

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

    2015-03-01

    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 μg/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

  4. Development and Validation of a Stability Indicating RP-UPLC Method for Determination of Quetiapine in Pharmaceutical Dosage Form

    PubMed Central

    Trivedi, Rakshit Kanubhai; Patel, Mukesh C.

    2011-01-01

    The present work reports a stability indicating reversed phase ultra performance liquid chromatography (RP-UPLC) method for the quantitative determination of quetiapine in pharmaceutical dosage form. The chromatographic separation is performed on an Agilent Eclipse Plus C18, RRHD 1.8 μm (50 mm x 2.1 mm) column using gradient elution. The optimized mobile phase consists of 0.1 % aqueous triethylamine (pH 7.2) as a solvent-A and 80:20 v/v mixture of acetonitrile and methanol as solvent-B. The eluted compounds are monitored at 252 nm wavelength using a UV detector. The developed method separates quetiapine from its five impurities/degradation products within a run time of 5 min. Stability indicating capability of the developed method is established by analyzing forced degradation samples in which the spectral purity of quetiapine is ascertained along with the separation of degradation products from analyte peak. The developed RP-UPLC method is validated as per International Conference on Harmonization (ICH) guidelines with respect to system suitability, specificity, precision, accuracy, linearity, robustness and filter compatibility. PMID:21617775

  5. Development, Optimization, and Validation of a Green and Stability-Indicating HPLC Method for Determination of Daptomycin in Lyophilized Powder.

    PubMed

    Tótoli, Eliane Gandolpho; Salgado, Hérida Regina Nunes

    2015-01-01

    Daptomycin is an antimicrobial that plays an important role in clinical practice today because it is considered a promising drug to combat resistant strains, such as methicilin and vancomycin-resistant Gram-positive bacteria. Considering the analysis of daptomycin in a pharmaceutical dosage form, the only method found in literature uses potentially toxic organic solvents. Therefore, the objective of this work was to develop a green and stability-indicating HPLC method for determination of daptomycin in lyophilized powder. The mobile phase was ethanol-water (55+45, v/v) at pH 4.5 pumped at a flow rate of 0.6 mL/min. A C18 column was used, and UV detection was performed at 221 nm. Stress degradation studies were conducted in order to demonstrate the specificity and stability-indicating capability of the method. The method was validated according to International Conference on Harmonization guidelines, proving to be linear (r=0.9996), precise, accurate, robust (demonstrated by the Plackett-Burman model), and specific within the range 20-70 μg/mL. The retention time of daptomycin was 5.8 min. It can be concluded that the validated method can be a fast, safe, and environmentally friendly alternative for the analysis of daptomycin. PMID:26525246

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

    PubMed Central

    2014-01-01

    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 μm) 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 μg mL-1 and naphazoline hydrochloride in 12.5-100 μg 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

  7. The unique stability of the photon indices in "dipping" Z-source GX 340+0 throughout spectral states

    NASA Astrophysics Data System (ADS)

    Seifina, Elena; Titarchuk, Lev; Frontera, Filippo

    We present an analysis of the spectral and timing properties of X-ray radiation from accreting neutron star source GX340+0 during its evolution when the electron temperature of the transition layer (TL) kTe 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_s1≤1 keV coming from the disk (first component Comptb1), and seed photons of temperature T_{s2}≤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_com1 and Gamma_{com2} of the Comptonized components are almost constant, Gamma_{com1} and Gamma_{com2} 2 when kTe 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 GX340+0 is similar to that previously established in the atoll sources 4U1728-34, 4U1820-30 and GX3+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_{com} increases during a spectral evolution from the low state to the high state and ultimately saturates at a high mass accretion rate

  8. A Validated Stability-Indicating and Stereoselective HPLC Method for the Determination of Lenalidomide Enantiomers in Bulk Form and Capsules.

    PubMed

    Alzoman, Nourah Z

    2016-01-01

    A simple, rapid and stability-indicating chiral HPLC (CHR-HPLC) method was designed for the enantiomeric separation of lenalidomide (LDM) in the presence of its degradation products. LDM was exposed to different accelerated stress factors. The degradation products were well resolved from the pure drug enantiomers. Separation of the LDM enantiomers was achieved on a LUX 5U cellulose-2 chiral column (250 × 4.6 mm i.d.) with a mobile phase consisting of methanol : glacial acetic acid : triethyl amine (100 : 0.01 : 0.01, v/v/v) at a flow rate of 1.2 mL/min. The detection wavelength was 220 nm, and ornidazole was the internal standard. The chiral method was validated in terms of its specificity, linearity, range, precision and accuracy as well as solution stability, robustness, limit of detection and limit of quantification. The calibration curve was linear for concentrations ranging from 2 to 1,000 ng/mL (r= 0.9999) for both LDM enantiomers. The proposed method, which met International Conference on Harmonization/Food and Drug Administration regulatory requirements, was utilized successfully for the determination of LDM in bulk and in capsules with acceptable accuracy and precision; the label demand percentages were 100.09 ± 0.80 and 99.97 ± 0.93 for the S-(-) and R-(+)-LDM enantiomers, respectively. Based on these results, this method should have great value when applied to quality control and stability studies of LDM. PMID:26850732

  9. A stability-Indicating HPLC Method for Simultaneous Determination of Creatine Phosphate Sodium and its Related Substances in Pharmaceutical Formulation.

    PubMed

    Xie, Zengkun; Wei, Lihua; Yang, Qin; Yang, Min; Pan, Hongchun; Liu, Hong

    2016-01-01

    The objective of the study was to develop a simple, specific and stability-indicating HPLC method for the simultaneous determination of creatine phosphate sodium (CPS) and its related substances in pharmaceutical formulation. Separation of creatine phosphate sodium from its major process impurities and degradation products was achieved on a Hypersil BDS C18 column (250 × 4.6 mm, 5 μm) with an aqueous mobile phase containing 0.2% (w/v) tetrabutylammonium hydroxide (TAH) and 0.2% (w/v) monopotassium phosphate adjusted to pH 6.6 with orthophosphoric acid at a flow rate of 1.0 mL min(-1). The analytes were detected at 210 nm. Different chromatographic parameters were carefully optimized. The relative response factors for creatine, creatinine and creatinine phosphate disodium salt relative to CPS were determined. The method has been validated with respect to solution stability, system suitability, LOD, LOQ, linearity, accuracy, precision, specificity and robustness. The validation criteria were met in all cases. The developed method was successfully applied to determine the purity of CPS in pharmaceutical formulation. PMID:27610152

  10. Stability-Indicating High-Performance Liquid Chromatography Assay for the Determination of Sulthiame in Pharmaceutical Dosage Forms.

    PubMed

    Haidar, Ammar; Kabiche, Sofiane; Majoul, Elyes; Balde, Issa-Bella; Fontan, Jean-Eudes; Cisternino, Salvatore; Schlatter, Joël

    2016-01-01

    A stability-indicating assay by reversed-phase high performance liquid chromatography method was developed and validated for the determination of sulthiame (STM). The chromatographic separation was achieved on a reversed-phase NovaPack C18 column and an isocratic mobile phase consisting of deionized water:methanol (70:30, v/v). The flow rate was 1.0 mL/min (ultraviolet detection at 210 nm). The STM was separated within 2.83 min. The linearity of the method was demonstrated in the range of 20.0-200.0 μg/mL and a coefficient of determination of r (2) = 0.9999. The limits of detection and quantification were 4.2 and 9.5 μg/mL, respectively. The intraday and interday precisions were less than 1%. Accuracy of the method ranged from 98.3% to 101.7%, with a relative standard deviation of <1%. STM was degraded by accelerated breakdown in alkaline, acidic, or oxidative stress conditions. This method allows accurate and reliable determination of STM for drug stability assay in pharmaceutical studies. PMID:27625574

  11. Stability-Indicating High-Performance Liquid Chromatography Assay for the Determination of Sulthiame in Pharmaceutical Dosage Forms

    PubMed Central

    Haidar, Ammar; Kabiche, Sofiane; Majoul, Elyes; Balde, Issa-Bella; Fontan, Jean-Eudes; Cisternino, Salvatore; Schlatter, Joël

    2016-01-01

    A stability-indicating assay by reversed-phase high performance liquid chromatography method was developed and validated for the determination of sulthiame (STM). The chromatographic separation was achieved on a reversed-phase NovaPack C18 column and an isocratic mobile phase consisting of deionized water:methanol (70:30, v/v). The flow rate was 1.0 mL/min (ultraviolet detection at 210 nm). The STM was separated within 2.83 min. The linearity of the method was demonstrated in the range of 20.0–200.0 μg/mL and a coefficient of determination of r2 = 0.9999. The limits of detection and quantification were 4.2 and 9.5 μg/mL, respectively. The intraday and interday precisions were less than 1%. Accuracy of the method ranged from 98.3% to 101.7%, with a relative standard deviation of <1%. STM was degraded by accelerated breakdown in alkaline, acidic, or oxidative stress conditions. This method allows accurate and reliable determination of STM for drug stability assay in pharmaceutical studies. PMID:27625574

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

    PubMed

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

    2011-11-01

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

  13. A stability-Indicating HPLC Method for Simultaneous Determination of Creatine Phosphate Sodium and its Related Substances in Pharmaceutical Formulation

    PubMed Central

    Xie, Zengkun; Wei, Lihua; Yang, Qin; Yang, Min; Pan, Hongchun; Liu, Hong

    2016-01-01

    The objective of the study was to develop a simple, specific and stability-indicating HPLC method for the simultaneous determination of creatine phosphate sodium (CPS) and its related substances in pharmaceutical formulation. Separation of creatine phosphate sodium from its major process impurities and degradation products was achieved on a Hypersil BDS C18 column (250 × 4.6 mm, 5 μm) with an aqueous mobile phase containing 0.2% (w/v) tetrabutylammonium hydroxide (TAH) and 0.2% (w/v) monopotassium phosphate adjusted to pH 6.6 with orthophosphoric acid at a flow rate of 1.0 mL min-1. The analytes were detected at 210 nm. Different chromatographic parameters were carefully optimized. The relative response factors for creatine, creatinine and creatinine phosphate disodium salt relative to CPS were determined. The method has been validated with respect to solution stability, system suitability, LOD, LOQ, linearity, accuracy, precision, specificity and robustness. The validation criteria were met in all cases. The developed method was successfully applied to determine the purity of CPS in pharmaceutical formulation. PMID:27610152

  14. Simultaneous quantification of related substances of perindopril tert-butylamine using a novel stability indicating liquid chromatographic method.

    PubMed

    Szabó, Zoltán-István; Réti, Zenkő-Zsuzsánna; Gagyi, László; Kis, Erika Lilla; Sipos, Emese

    2015-03-01

    A novel stability indicating gradient reverse-phased high-performance liquid chromatographic method has been developed for the quantification of impurities of perindopril tert-butylamine (PER) in pharmaceutical dosage form. Separation of the active substance and its known (Impurities B, C, D, E, F) and unknown impurities was achieved on a BDS Hypersil C18 column (250 mm × 4.6 mm, 5 µm), thermostated at 70°C, using a mobile phase comprised of aqueous solution of sodium 1-heptanesulfonate adjusted to pH 2 with perchloric acid and acetonitrile. The flow rate was maintained at 1.5 mL min(-1), injection volume of 20 µL was utilized and detection of analytes was performed at 215 nm. The developed method was validated in accordance with current ICH Guidelines for all suggested parameters, including forced degradation studies and proved to be linear, accurate, precise and suitable for the impurity testing of PER, being subsequently applied during on-going stability studies of a newly developed generic formulation. PMID:25616989

  15. LipStaT: The Lip Stabilization Technique- Indications and Guidelines for Case Selection and Classification of Excessive Gingival Display.

    PubMed

    Bhola, Monish; Fairbairn, Peter Jm; Kolhatkar, Shilpa; Chu, Stephen J; Morris, Tamaara; de Campos, Marinele

    2015-01-01

    Excessive gingival display (EGD) is an esthetic concern affecting a substantial portion of the population. Identification, diagnosis, and classification of all factors resulting in EGD are imperative for its appropriate management. While many authors have described these factors individually, the authors of the current study propose a simple classification, which includes major etiologies of EGD. Where EGD is associated with maxillary lip hypermobility, a proposal of a subclass 1-3 is offered. A "decision-making tree" to help guide clinicians in managing EGD is included. A detailed description of the lip stabilization technique (LipStaT), including indications, surgical guidelines, postsurgical management, and clinical cases with long-term follow-up, is presented. PMID:26133145

  16. Pharmacokinetic study of arctigenin in rat plasma and organ tissue by RP-HPLC method.

    PubMed

    He, Fan; Dou, De-Qiang; Hou, Qiang; Sun, Yu; Kang, Ting-Guo

    2013-01-01

    A high-performance liquid chromatography (HPLC) technique was developed for the determination of arctigenin in plasma and various organs of rats after the oral administration of 30, 50 and 70 mgkg(-1) of arctigenin to the Sprague-Dawley rats. Results showed that the validated HPLC method was simple, fast, reproducible and suitable to the determination of arctigenin in rat plasma and organ tissue and one-compartmental model with zero-order absorption process can well describe the changes of arctigenin concentration in the plasma. The concentration of compound was highest in the spleen, less in the liver and the least in the lung. PMID:22404522

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

    PubMed

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

    2008-09-01

    Rapid, precise, accurate, specific and sensitive reverse phase liquid chromatographic and absorbance ratio spectrophotometric methods have been developed for the simultaneous analysis of ambroxol hydrochloride and cetirizine hydrochloride in their tablet formulation. The chromatographic methods were standardized using a HIQ SIL-C(18) column (250×4.6 mm i.d., 10 μm particle size) with UV detection at 229 nm and mobile phase consisting of methanol-acetonitrile-water (40:40:20, v/v/v). Ambroxol hydrochloride and cetirizine hydrochloride have absorbance maxima at 243 nm and 229 nm, respectively. The isoabsorptive wavelength for both the drugs was 236 nm. For absorbance ratio method developed, wavelengths selected were 243 nm and 236 nm. The proposed methods were successfully applied to the determination of ambroxol hydrochloride and cetirizine hydrochloride in tablets, with high percentage of recovery, good accuracy and acceptable precision. Different analytical performance parameters such as linearity, precision, accuracy, limit of detection, limit of quantitation and robustness were determined according to International Conference on Harmonization ICH Q2B guidelines. Results of analysis of the developed method were compared by performing ANOVA. PMID:21394256

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

    PubMed Central

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

    2011-01-01

    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 λmax of 224 nm, using Princeton Sphere-100 C18 (250×4.6 mm. 5 μ) 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 R2 values 0.994 in the range of 5 to 30 μg/ml 0.1 to 1 μg/ml for diethylcarbamazine and levocetirizine, respectively. Hence this method can be applied for quantification of different formulations containing diethylcarbamazine and levocetirizine simultaneously. PMID:22457560

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

    PubMed

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

    2014-04-01

    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 μg mL(-1), 38.46±2.26 μg 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

  20. Regularities of Anthocyanins Retention in RP HPLC for “Water–Acetonitrile–Phosphoric Acid” Mobile Phases

    PubMed Central

    Deineka, V. I.; Deineka, L. A.; Saenko, I. I.

    2015-01-01

    The influence of exchange of HCOOH (System 2) by phosphoric acid (System 1) for acidification of the “acetonitrile–water” mobile phases for reversed-phase HPLC of anthocyanins was investigated in the framework of relative retention analysis. The differences and similarities of anthocyanins separation were revealed. It has been shown that some common features of the quantitative relationships may be used for preliminary anthocyanins structure differentiation, according to the number of OH-groups in anthocyanidin backbone as well as to a number of saccharide molecules in glycoside radicals in position 3 of the anthocyanin without MS detection. PMID:25692073

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

    PubMed

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

    2011-05-01

    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 λ(max) of 224 nm, using Princeton Sphere-100 C(18) (250×4.6 mm. 5 μ) 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 μg/ml 0.1 to 1 μg/ml for diethylcarbamazine and levocetirizine, respectively. Hence this method can be applied for quantification of different formulations containing diethylcarbamazine and levocetirizine simultaneously. PMID:22457560

  2. RP-HPLC Method for the Determination of Losartan Potassium and Ramipril in Combined Dosage Form

    PubMed Central

    Rao, K. Srinivasa; Srinivas, K.

    2010-01-01

    A simple, specific and accurate reverse phase liquid chromatographic method was developed for the simultaneous determination of losartan potassium and ramipril in table dosage forms. A hypersil ODS C18, 4.6×250 mm, 5 μm column in isocratic mode, with mobile phase acetonitrile:methanol:10 mM tetra butyl ammonium hydrogen sulphate in water in the ratio of 30:30:40% v/v/v was used. The flow rate was 1.0 ml/min and effluent was monitored at 210 nm. The retention times of losartan potassium and ramipril were 4.7 and 3.3 min, respectively. The linearity range for losartan potassium and ramipril were in the range of 0.04-100 μg/ml and 0.2-300 μg/ml, respectively. The proposed method was also validated and successfully applied to the estimation of losartan potassium and ramipril in combined tablet formulations. PMID:20582199

  3. Development and Validation of RP-HPLC Method for the Estimation of Ivabradine Hydrochloride in Tablets

    PubMed Central

    Seerapu, Sunitha; Srinivasan, B. P.

    2010-01-01

    A simple, sensitive, precise and robust reverse–phase high-performance liquid chromatographic method for analysis of ivabradine hydrochloride in pharmaceutical formulations was developed and validated as per ICH guidelines. The separation was performed on SS Wakosil C18AR, 250×4.6 mm, 5 μm column with methanol:25 mM phosphate buffer (60:40 v/v), adjusted to pH 6.5 with orthophosphoric acid, added drop wise, as mobile phase. A well defined chromatographic peak of Ivabradine hydrochloride was exhibited with a retention time of 6.55±0.05 min and tailing factor of 1.14 at the flow rate of 0.8 ml/min and at ambient temperature, when monitored at 285 nm. The linear regression analysis data for calibration plots showed good linear relationship with R=0.9998 in the concentration range of 30-210 μg/ml. The method was validated for precision, recovery and robustness. Intra and Inter-day precision (% relative standard deviation) were always less than 2%. The method showed the mean % recovery of 99.00 and 98.55 % for Ivabrad and Inapure tablets, respectively. The proposed method has been successfully applied to the commercial tablets without any interference of excipients. PMID:21695008

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

    PubMed Central

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

    2012-01-01

    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 μm) 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 μl injection volume and the column temperature was maintained at 50°. The limit of detection and limit of quantitation were found to be 0.02 μg/ml and 0.07 μg/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 μg/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

  5. Stability indicating validated HPLC method for quantification of levothyroxine with eight degradation peaks in the presence of excipients.

    PubMed

    Shah, R B; Bryant, A; Collier, J; Habib, M J; Khan, M A

    2008-08-01

    A simple, sensitive, accurate, and robust stability indicating analytical method is presented for identification, separation, and quantitation of l-thyroxine and eight degradation impurities with an internal standard. The method was used in the presence of commonly used formulation excipients such as butylated hydroxyanisole, povidone, crospovidone, croscarmellose sodium, mannitol, sucrose, acacia, lactose monohydrate, confectionary sugar, microcrystalline cellulose, sodium laurel sulfate, magnesium stearate, talc, and silicon dioxide. The two active thyroid hormones: 3,3',5,5'-tetra-iodo-l-thyronine (l-thyroxine-T4) and 3,3',5-tri-iodo-l-thyronine (T3) and degradation products including di-iodothyronine (T2), thyronine (T0), tyrosine (Tyr), di-iodotyrosine (DIT), mono-iodotyrosine (MIT), 3,3',5,5'-tetra-iodothyroacetic acid (T4AA) and 3,3',5-tri-iodothyroacetic acid (T3AA) were assayed by the current method. The separation of l-thyroxine and eight metabolites along with theophylline (internal standard) was achieved using a C18 column (25 degrees C) with a mobile phase of trifluoroacetic acid (0.1%, v/v, pH 3)-acetonitrile in gradient elution at 0.8 ml/min at 223 nm. The sample diluent was 0.01 M methanolic NaOH. Method was validated according to FDA, USP, and ICH guidelines for inter-day accuracy, precision, and robustness after checking performance with system suitability. Tyr (4.97 min), theophylline (9.09 min), MIT (9.55 min), DIT (11.37 min), T0 (11.63 min), T2 (14.47 min), T3 (16.29 min), T4 (17.60 min), T3AA (22.71 min), and T4AA (24.83 min) separated in a single chromatographic run. Linear relationship (r2>0.99) was observed between the peak area ratio and the concentrations for all of the compounds within the range of 2-20 microg/ml. The total time for analysis, equilibration and recovery was 40 min. The method was shown to separate well from commonly employed formulation excipients. Accuracy ranged from 95 to 105% for T4 and 90 to 110% for all other

  6. Development and Validation of Stability-Indicating Method for the Simultaneous Determination of Ketoconazole and Beauvericin in Pharmaceutical Tablets.

    PubMed

    Tian, Tingting; Yang, Min; Zhao, Zhongxi; Luan, Yuxia; Tang, Xuan; Zhu, Meihua; Liu, Yan

    2016-03-01

    In this work, a stability-indicating high-performance liquid chromatography (HPLC) method was developed and validated for the simultaneous analysis of ketoconazole (KCZ) and beauvericin (BEA) as well as their degradation products in the combination tablets. KCZ is a synthetic broad-spectrum antifungal agent with the risk of hepatoxicity. However, it was found that the combined use of KCZ and BEA in their low dose had not only maintained the antifungal activity of KCZ but also significantly reduced the liver toxicity. The method development was started from forced degradation studies including acidic, basic, oxidative, thermal and photolytic degradations in the solution mixtures of KCZ and BEA. The forced degradation study results indicate that hydrolysis and oxidation were the major degradation pathways for KCZ while BEA mainly decomposed under basic hydrolytic condition. The newly developed HPLC method was validated according to the International Conference on Harmonization (ICH) guidelines with respect to specificity, linearity, precision, accuracy, limits of detection and quantification and robustness. The method validation results indicate that the new HPLC method could be successfully applied in the simultaneous detection and quantitation of KCZ and BEA and their degradation products. For example, the accuracy and the precision of the method were determined by a recovery study at 80, 100 and 120% of the tablet dosage levels. The recovery was found to be 99.6-100.2 for both analytes with a relative standard deviation of no more than 1.2% (n = 5) at any concentration level. This new method can be used for further development of various KCZ and BEA combination drug products. PMID:26486149

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

    PubMed

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

    2009-01-01

    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

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

    PubMed Central

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

    2013-01-01

    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 μg/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

  9. Measuring sperm whales from their clicks: Stability of interpulse intervals and validation that they indicate whale length

    NASA Astrophysics Data System (ADS)

    Rhinelander, Marcus Q.; Dawson, Stephen M.

    2004-04-01

    Multiple pulses can often be distinguished in the clicks of sperm whales (Physeter macrocephalus). Norris and Harvey [in Animal Orientation and Navigation, NASA SP-262 (1972), pp. 397-417] proposed that this results from reflections within the head, and thus that interpulse interval (IPI) is an indicator of head length, and by extrapolation, total length. For this idea to hold, IPIs must be stable within individuals, but differ systematically among individuals of different size. IPI stability was examined in photographically identified individuals recorded repeatedly over different dives, days, and years. IPI variation among dives in a single day and days in a single year was statistically significant, although small in magnitude (it would change total length estimates by <3%). As expected, IPIs varied significantly among individuals. Most individuals showed significant increases in IPIs over several years, suggesting growth. Mean total lengths calculated from published IPI regressions were 13.1 to 16.1 m, longer than photogrammetric estimates of the same whales (12.3 to 15.3 m). These discrepancies probably arise from the paucity of large (12-16 m) whales in data used in published regressions. A new regression is offered for this size range.

  10. Development of a validated stability-indicating HPTLC method for rufinamide in bulk and its pharmaceutical dosage form.

    PubMed

    Patel, Apexa; Patwari, Arpit; Suhagia, Bhanubhai

    2014-01-01

    A sensitive, selective, precise and stability indicating a high-performance thin layer chromatographic method for the analysis of rufinamide (Rf) in bulk drug and its formulations was developed and validated. The method employed thin layer chromatography aluminum plates precoated with silica gel 60 F254 as the stationary phase. The solvent system consisted of chloroform : methanol : glacial acetic acid (9 : 1 : 0.1 v/v/v). This system was found to give compact spots for Rf (Rf value of 0.68 ± 0.02). Rf was subjected to acid and alkali hydrolysis, oxidation, photodegradation and dry heat treatment. Also, the degraded products were well separated from the pure drug. Densitometric analysis of Rf was carried out in the absorbance mode at 210 nm, which is wavelength maxima for the degradant. The linear regression data for the calibration plots showed a good linear relationship with an r(2) of 0.9989 in the concentration range of 1,000-3,500 ng. The method was validated for precision, accuracy, ruggedness and recovery. The limits of detection and quantitation were 196.59 and 595.74 ng spot(-1), respectively. The drug undergoes degradation under acidic and basic conditions. All the peaks of degraded products were resolved from the standard drug with significantly different Rf values. PMID:24297523

  11. Quantification of halobetasol propionate and its impurities present in topical dosage forms by stability-indicating LC method.

    PubMed

    Nalwade, Santaji; Reddy, Vangala Ranga; Kulkarni, Dipak; Todamal, Sandip

    2015-01-01

    A novel, sensitive, stability-indicating, gradient, reverse-phase high-performance liquid chromatographic method has been developed for quantitative determination of halobetasol propionate and its impurities in topical dosage forms. The chromatographic separation was achieved on a Phenomenex Synergi polar reverse phase, 250 × 4.6 mm, 4 µm column. Mobile phase A comprises a mixture of 0.01 M KH2PO4 buffer containing 0.2% 1-octane sulfonic acid sodium salt (pH 3.0), acetonitrile and methanol in the ratio 80:15:05 (v/v/v), respectively, and mobile phase B contains a mixture of 0.01 M KH2PO4 buffer containing 0.2% 1-octane sulfonic acid sodium salt (pH 3.0), acetonitrile and methanol in the ratio 20:70:10 (v/v/v), respectively. The flow rate is 0.8 mL min(-1). The column compartment temperature is set at 40°C and the detection wavelength is set at 240 nm. The resolutions between Halobetasol propionate and all the impurities are >2.0 for all pairs of compounds. The drug product was subjected to International Conference on Harmonization (ICH)-prescribed hydrolytic, oxidative, photolytic and thermal stress conditions. The method is validated as per the ICH guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision, robustness and ruggedness. PMID:24784115

  12. Kinetic Study of the Alkaline Degradation of Oseltamivir Phosphate and Valacyclovir Hydrochloride using Validated Stability Indicating HPLC.

    PubMed

    Al-Bagary, Ramzia I; El-Zaher, Asmaa A; Morsy, Fahima A; Fouad, Mai M

    2014-01-01

    Aqueous alkaline degradation was performed for oseltamivir phosphate (OP) and valacyclovir hydrochloride (VA). Isocratic stability indicating the use of high-performance liquid chromatography (HPLC) was presented for each drug in the presence of its degradation product. The separations were performed using the Nucleosil ODS column and a mobile phase consisting of phosphate buffer (pH = 7), acetonitrile, and methanol 50:25:25 (v/v/v) for OP. For VA separation, a Nucleosil CN column using phosphate buffer (pH = 7) and methanol 85:15 (v/v) was used as a mobile phase. Ultraviolet detection at 210 nm and 254 nm was used for OP and VA, respectively. The method showed high sensitivity concerning linearity, accuracy, and precision over the range 1-250 μg mL(-1) for both drugs. The proposed method was used to determine the drug in its pharmaceutical formulation and to investigate the degradation kinetics of each drug's alkaline-stressed samples. The reactions were found to follow a first-order reaction. The activation energy could also be estimated. International Conference on Harmonisation guidelines were adopted for method validation. PMID:24932100

  13. Stability-indicating High-performance Liquid Chromatography Method for Simultaneous Determination of Aminophylline and Chlorpheniramine Maleate in Pharmaceutical Formulations

    PubMed Central

    Ali, A.; Ahmed, M.; Mahmud, T.; Qadir, M. A.; Nadeem, K.; Saleem, A.

    2015-01-01

    The present work deals with the development and validation of method for simultaneous determination of antihistaminic drugs in pharmaceutical formulations. A precise, specific and accurate reverse phase-high-performance liquid chromatography method for the simultaneous measurement of aminophylline and chlorpheniramine maleate was developed. The separation of drugs was achieved on C-18 (5 μm, 250×4.6 mm) high-performance liquid chromatography column. The runtime for analysis was 10 min. Mobile phase is mixture containing dilute H2SO4:methanol (60:40% v/v) with flow rate adjusted at 1.5 ml/min. The detection of components was performed at a wavelength of 264 nm. Retention times of aminophylline and chlorphinramine maleate were found to be 2.00 and 3.25 min, respectively. Linearity was found in the range of 16-24 μg/ml for chlorpheniramine maleate and 102.4-153.6 μg/ml for aminophylline with a correlation coefficient of 0.9998 and 0.9996, respectively. High peak purity index of 99.99% indicated the complete separation of analytes in the presence of degradation products is justification of method stability. Linearity, accuracy, specificity, precision and robustness studies were performed for method validation. PMID:26798164

  14. Development and Validation of a Stability-Indicating Liquid Chromatographic Method for Estimating Olmesartan Medoxomil Using Quality by Design.

    PubMed

    Beg, Sarwar; Sharma, Gajanand; Katare, O P; Lohan, Shikha; Singh, Bhupinder

    2015-08-01

    The current studies entail systematic quality by design (QbD)-based development of a simple, rapid, sensitive and cost-effective stability-indicating method for the estimation of olmesartan medoxomil. Quality target method profile was defined and critical analytical attributes (CAAs) for the reverse-phase liquid chromatography method earmarked. Chromatographic separation accomplished on a C18 column using acetonitrile and water (containing 0.1% orthophosphoric acid, pH 3.5) in 40 : 60 (v/v) as mobile phase at a flow rate of 1.0 mL/min with UV detection at 243 nm. Risk assessment studies and screening studies facilitated comprehensive understanding of the factors affecting CAAs. The mobile phase ratio and flow rate were identified as critical method parameters (CMPs) and were systematically optimized using face-centered cubic design, evaluating for CAAs, namely peak area, retention time, theoretical plates and peak tailing. Statistical modelization was accomplished followed by response surface analysis for comprehending plausible interaction(s) among CMPs. Search for optimum solution was conducted through numerical and graphical optimization for demarcating the design space. Analytical method validation and subsequent forced degradation studies corroborated the method to be highly efficient for routine analysis of drug and its degradation products. The studies successfully demonstrate the utility of QbD approach for developing the highly sensitive liquid chromatographic method with enhanced method performance. PMID:25583970

  15. Quality by design (QbD) based development of a stability indicating HPLC method for drug and impurities.

    PubMed

    Karmarkar, S; Garber, R; Genchanok, Y; George, S; Yang, X; Hammond, R

    2011-01-01

    In this paper, an application of Quality by Design (QbD) concepts to the development of a stability indicating HPLC method for a complex pain management drug product containing drug substance, two preservatives, and their degradants is described. The QbD approach consisted of (i) developing a full understanding of the intended purpose, (ii) developing predictive solutions, (iii) designing a meaningful system suitability solution that helps to identify failure modes, and (iv) following design of experiments (DOE) approach. The starting method lacked any resolution among drug degradant and preservative oxidative degradant peaks, and peaks for preservative and another drug degradant. The method optimization was accomplished using Fusion AE™ software (S-Matrix Corporation, Eureka, CA) that follows a DOE approach. Column temperature (50 ± 5°C), mobile phase buffer pH (2.9 ± 0.2), initial % acetonitrile (ACN, 2 ± 1%), and initial hold time (2.5, 5, or 10 min) of the HPLC method were simultaneously studied to optimize separation of the unresolved peaks. The optimized HPLC conditions (column temperature of 50°C, buffer pH of 3.1, 3% initial ACN with 2.5 min initial hold) resulted in fully resolved peaks in the two critical pairs. The QbD based method development helped in generating a design space and operating space with knowledge of all method performance characteristics and limitations and successful method robustness within the operating space. PMID:21682993

  16. Stability-indicating High-performance Liquid Chromatography Method for Simultaneous Determination of Aminophylline and Chlorpheniramine Maleate in Pharmaceutical Formulations.

    PubMed

    Ali, A; Ahmed, M; Mahmud, T; Qadir, M A; Nadeem, K; Saleem, A

    2015-01-01

    The present work deals with the development and validation of method for simultaneous determination of antihistaminic drugs in pharmaceutical formulations. A precise, specific and accurate reverse phase-high-performance liquid chromatography method for the simultaneous measurement of aminophylline and chlorpheniramine maleate was developed. The separation of drugs was achieved on C-18 (5 μm, 250×4.6 mm) high-performance liquid chromatography column. The runtime for analysis was 10 min. Mobile phase is mixture containing dilute H2SO4:methanol (60:40% v/v) with flow rate adjusted at 1.5 ml/min. The detection of components was performed at a wavelength of 264 nm. Retention times of aminophylline and chlorphinramine maleate were found to be 2.00 and 3.25 min, respectively. Linearity was found in the range of 16-24 μg/ml for chlorpheniramine maleate and 102.4-153.6 μg/ml for aminophylline with a correlation coefficient of 0.9998 and 0.9996, respectively. High peak purity index of 99.99% indicated the complete separation of analytes in the presence of degradation products is justification of method stability. Linearity, accuracy, specificity, precision and robustness studies were performed for method validation. PMID:26798164

  17. Stability of the Associations between Early Life Risk Indicators and Adolescent Overweight over the Evolving Obesity Epidemic

    PubMed Central

    Graversen, Lise; Sørensen, Thorkild I. A.; Petersen, Liselotte; Sovio, Ulla; Kaakinen, Marika; Sandbæk, Annelli; Laitinen, Jaana; Taanila, Anja; Pouta, Anneli

    2014-01-01

    Background Pre- and perinatal factors and preschool body size may help identify children developing overweight, but these factors might have changed during the development of the obesity epidemic. Objective We aimed to assess the associations between early life risk indicators and overweight at the age of 9 and 15 years at different stages of the obesity epidemic. Methods We used two population-based Northern Finland Birth Cohorts including 4111 children born in 1966 (NFBC1966) and 5414 children born in 1985–1986 (NFBC1986). In both cohorts, we used the same a priori defined prenatal factors, maternal body mass index (BMI), birth weight, infant weight (age 5 months and 1 year), and preschool BMI (age 2–5 years). We used internal references in early childhood to define percentiles of body size (<50, 50–75, 75–90 and >90) and generalized linear models to study the association with overweight, according to the International Obesity Taskforce (IOTF) definitions, at the ages of 9 and 15 years. Results The prevalence of overweight at the age of 15 was 9% for children born in 1966 and 16% for children born in 1986. However, medians of infant weight and preschool BMI changed little between the cohorts, and we found similar associations between maternal BMI, infant weight, preschool BMI, and later overweight in the two cohorts. At 5 years, children above the 90th percentile had approximately a 12 times higher risk of being overweight at the age of 15 years compared to children below the 50th percentile in both cohorts. Conclusions The associations between early body size and adolescent overweight showed remarkable stability, despite the increase in prevalence of overweight over the 20 years between the cohorts. Using consequently defined internal percentiles may be a valuable tool in clinical practice. PMID:24748033

  18. A Stability-Indicating HPLC Method for the Determination of Nitrosylcobalamin (NO-Cbl), a Novel Vitamin B12 Analog

    PubMed Central

    Dunphy, Michael J.; Sysel, Annette M.; Lupica, Joseph A.; Griffith, Kristie; Sherrod, Taylor

    2014-01-01

    Nitrosylcobalamin (NO-Cbl), a novel vitamin B12 analog and anti-tumor agent, functions as a biologic ‘Trojan horse’, utilizing the vitamin B12 transcobalamin II transport protein and cell surface receptor to specifically target cancer cells. a stability-indicating HPLC method was developed for the detection of NO-Cbl during forced degradation studies. This method utilized an ascentis® RP-amide (150 mm × 4.6 mm, 5 μm) column at 35 °C with a mobile phase (1.0 mL min−1) combining a gradient of methanol and an acetate buffer at pH 6.0. Detection wavelengths of 450 and 254 nm were used to detect corrin and non-corrin-based products, respectively. NO-Cbl, synthesized from hydroxocobalamin and pure nitric oxide gas, was subjected to degradative stress conditions including oxidation, hydrolysis and thermal and radiant energy challenge. The method was validated by assessing linearity, accuracy, precision, detection and quantitation limits and robustness. The method was applied successfully for purity assessment of synthesized NO-Cbl and for the determination of NO-Cbl during kinetic studies in aqueous solution and in solid-state degradation assessments. This HPLC method is suitable for the separation of cobalamins in aqueous and methanolic solutions, for routine detection of NO-Cbl and for purity assessment of synthesized NO-Cbl. additionally, this method has potential application in identification and monitoring of diseases involving altered nitric oxide homeostasis where vitamin B12 therapy is utilized to scavenge excess nitric oxide, subsequently resulting in the in vivo production of NO-Cbl. PMID:24855323

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  20. Effect of chain length on the formation and stability of synthetic alpha-helical coiled coils.

    PubMed

    Su, J Y; Hodges, R S; Kay, C M

    1994-12-27

    A series of polypeptides containing 9, 12, 16, 19, 23, 26, 30, 33, and 35 amino acid residues was designed to investigate the effects of peptide chain length on the formation and stability of two-stranded alpha-helical dimers or coiled coils. These peptides were synthesized by the solid-phase method, purified by reversed-phase high-performance liquid chromatography (RP-HPLC), and characterized by RP-HPLC, amino acid composition analysis, and mass spectrometry. The amphipathic alpha-helical peptides were designed to dimerize by interchain hydrophobic interactions at positions a and d and interchain salt bridges between lysine and glutamic acid residues at positions e and g of the repeating heptad sequence of Glu-Ile-Glu-Ala-Leu-Lys-Ala (g-a-b-c-d-e-f). The ability of these peptides to form alpha-helical structures in the presence and absence of a helix-inducing reagent (trifluoroethanol) was monitored by circular dichroism spectroscopy. The helicity of the peptides increased with increasing chain length in a cooperative manner. A minimum of three heptads corresponding to six helical turns was required for a peptide to adopt the two-stranded alpha-helical coiled coil conformation in aqueous medium. The increased stability of the peptides as a result of an increase in hydrophobic interactions (chain length) was demonstrated by the shift in the transitions of the guanidine hydrochloride (Gdn.HCl) denaturation and thermal unfolding profiles. The concentrations of denaturant (Gdn.HCl) required to achieve 50% denaturation are 3.2, 4.9, 6.9, and 7.5 M for peptides 23r, 26r, 30r, and 33r, respectively, in aqueous medium. However, the effect of a chain length increase on coiled-coil stability was not additive. The melting temperature, Tm, at which 50% of the helicity is lost, increased by 34 degrees C in changing the peptide chain length from 23 to 26; however, that shift was only 14 degrees C when the chain length was increased from 30 to 33 residues. These results are

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

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

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

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

    PubMed

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

    2014-11-20

    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

  3. Isolation, Identification, and Characterisation of Degradation Products and the Development and Validation of a Stability-Indicating Method for the Estimation of Impurities in the Tolterodine Tartrate Formulation

    PubMed Central

    Prakash, Lakkireddy; Himaja, Malipeddi; Vasudev, Rudraraju

    2015-01-01

    A short and sensitive stability-indicating gradient RP-UPLC method was developed for the quantitative determination of process-related impurities and degradation products of tolterodine tartrate in pharmaceutical formulations. The method was developed by using the Waters ACQUITY UPLC™ BEH shield RP18 (2.1 × 100 mm, 1.7 μm) column with a mobile phase containing a gradient mixture of solvent A and B at a detection wavelength of 210 nm. During the stress study, the degradation products of tolterodine tartrate were well-resolved from tolterodine and its impurities and the mass balances were 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, ruggedness, and robustness. During the stability (40°C/75% RH, 3 months) analysis of the drug product, one unknown impurity was detected by the above stability-indicating method. The unknown impurity was isolated by preparative HPLC and subjected to mass and NMR studies. Based on the spectral data, the unknown impurity was characterised as 2-(3-amino-1-phenylpropyl)-4-methylphenol (des-N,N-diisopropyl tolterodine). Structural elucidation of the impurity by spectral data is discussed in detail. PMID:26839802

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

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

    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.

  5. [DYNAMICS OF BACTERIOLOGICAL AND PLANIMETRIC INDICES OF THE WOUND UNDER THE ACTION OF THE SILVER NANOPARTICLES, STABILIZED BY MEXIDOL AND POLYVINYLPYRROLIDONE].

    PubMed

    Lyakhovskyi, V I; Lobahn, G A; Gancho, O V; Vazhnycha, O M; Kolomiyets, S V; Jaber, V Kh O

    2016-04-01

    Changes in bacteriological indices through the square of the wound of chemical origin under local impact of the silver nanoparticles (NP), stabilized by 2-ethyl-6-methyl-3-hydroxypyridine succinate (mexidol) and polyvinylpyrrolidone were studied. The wounds of submandibular region were simulated in white rats, using injection of 10% solution of calcium chloride with further opening of necrotic foci and open management of the wound. Beginning from the fifth day, every day the wound was irrigated with liquid, which have contented the stabilized NP of the silver, 0.05% water solution of chlorhexidine or isotonic solution of the the sodium chloride (control). There was established, that the silver NP impact antiseptically and regenerative while the wound treatment, and reduce during 10 days microbial contamination of exudate in 24 times, the wound square--in three times in comparison with original indices. These changes were identical to those while application of chlorhexidine. PMID:27434961

  6. A Novel, Rapid, and Validated Stability-Indicating UPLC Method for the Estimation of Drotaverine Hydrochloride and Ibuprofen Impurities in Oral Solid Dosage Form.

    PubMed

    Vijay Kumar, Rekulapally; Rao, Vinay U; Anil Kumar, N; Venkata Subbaiah, B

    2015-01-01

    A novel, stability-indicating, reversed-phase ultra-performance liquid chromatographic (RP-UPLC) method was developed for the determination of pure drotaverine hydrochloride and ibuprofen in the presence of their impurities and degradation products. The method was developed using a Waters UPLC BEH C18, 100 × 2.1 mm, 1.7 µm column with a flow rate of 0.3 mL/min and detector wavelength at 210 nm. The mobile phase consisted of potassium dihydrogen orthophosphate buffer and acetonitrile. Drotaverine hydrochloride and ibuprofen were subjected to the stress conditions of oxidative, acid, base, photolytic, and thermal degradation. Degradation products resulting from the stress studies were well-resolved, thus confirming the test method as stability-indicating. Validation of the method was carried out as per International Conference on Harmonization guidelines. PMID:26839839

  7. A Novel, Rapid, and Validated Stability-Indicating UPLC Method for the Estimation of Drotaverine Hydrochloride and Ibuprofen Impurities in Oral Solid Dosage Form

    PubMed Central

    Vijay Kumar, Rekulapally; Rao, Vinay U.; Anil Kumar, N.; Venkata Subbaiah, B.

    2015-01-01

    A novel, stability-indicating, reversed-phase ultra-performance liquid chromatographic (RP-UPLC) method was developed for the determination of pure drotaverine hydrochloride and ibuprofen in the presence of their impurities and degradation products. The method was developed using a Waters UPLC BEH C18, 100 × 2.1 mm, 1.7 µm column with a flow rate of 0.3 mL/min and detector wavelength at 210 nm. The mobile phase consisted of potassium dihydrogen orthophosphate buffer and acetonitrile. Drotaverine hydrochloride and ibuprofen were subjected to the stress conditions of oxidative, acid, base, photolytic, and thermal degradation. Degradation products resulting from the stress studies were well-resolved, thus confirming the test method as stability-indicating. Validation of the method was carried out as per International Conference on Harmonization guidelines. PMID:26839839

  8. Stability-indicating spectrophotometric methods for determination of the anticoagulant drug apixaban in the presence of its hydrolytic degradation product.

    PubMed

    Tantawy, Mahmoud A; El-Ragehy, Nariman A; Hassan, Nagiba Y; Abdelkawy, Mohamed

    2016-04-15

    Apixaban (a novel anticoagulant agent) was subjected to a stress stability study including acid, alkali, oxidative, photolytic, and thermal degradation. The drug was found to be only liable to acidic and alkaline hydrolysis. The degradation product was then isolated and identified by IR and GC-mass spectrometry. Four spectrophotometric methods, namely; first derivative (D(1)), derivative ratio (DR), ratio difference (RD) and mean centering of ratio spectra (MCR), have been suggested for the determination of apixaban in presence of its hydrolytic degradation product. The proposed methods do not require any preliminary separation step. The accuracy, precision and linearity ranges of the proposed methods were determined, and the methods were validated as per ICH guidelines and the specificity was assessed by analyzing synthetic mixtures containing different percentages of the degradation product with the drug. The developed methods were successfully applied for the determination of apixaban in bulk powder and its tablet dosage form. PMID:26824484

  9. Stability-indicating spectrophotometric methods for determination of the anticoagulant drug apixaban in the presence of its hydrolytic degradation product

    NASA Astrophysics Data System (ADS)

    Tantawy, Mahmoud A.; El-Ragehy, Nariman A.; Hassan, Nagiba Y.; Abdelkawy, Mohamed

    2016-04-01

    Apixaban (a novel anticoagulant agent) was subjected to a stress stability study including acid, alkali, oxidative, photolytic, and thermal degradation. The drug was found to be only liable to acidic and alkaline hydrolysis. The degradation product was then isolated and identified by IR and GC-mass spectrometry. Four spectrophotometric methods, namely; first derivative (D1), derivative ratio (DR), ratio difference (RD) and mean centering of ratio spectra (MCR), have been suggested for the determination of apixaban in presence of its hydrolytic degradation product. The proposed methods do not require any preliminary separation step. The accuracy, precision and linearity ranges of the proposed methods were determined, and the methods were validated as per ICH guidelines and the specificity was assessed by analyzing synthetic mixtures containing different percentages of the degradation product with the drug. The developed methods were successfully applied for the determination of apixaban in bulk powder and its tablet dosage form.

  10. Integrated Community Profiling Indicates Long-Term Temporal Stability of the Predominant Faecal Microbiota in Captive Cheetahs

    PubMed Central

    Becker, Anne A. M. J.; Janssens, Geert P. J.; Snauwaert, Cindy; Hesta, Myriam; Huys, Geert

    2015-01-01

    Understanding the symbiotic relationship between gut microbes and their animal host requires characterization of the core microbiota across populations and in time. Especially in captive populations of endangered wildlife species such as the cheetah (Acinonyx jubatus), this knowledge is a key element to enhance feeding strategies and reduce gastrointestinal disorders. In order to investigate the temporal stability of the intestinal microbiota in cheetahs under human care, we conducted a longitudinal study over a 3-year period with bimonthly faecal sampling of 5 cheetahs housed in two European zoos. For this purpose, an integrated 16S rRNA DGGE-clone library approach was used in combination with a series of real-time PCR assays. Our findings disclosed a stable faecal microbiota, beyond intestinal community variations that were detected between zoo sample sets or between animals. The core of this microbiota was dominated by members of Clostridium clusters I, XI and XIVa, with mean concentrations ranging from 7.5-9.2 log10 CFU/g faeces and with significant positive correlations between these clusters (P<0.05), and by Lactobacillaceae. Moving window analysis of DGGE profiles revealed 23.3-25.6% change between consecutive samples for four of the cheetahs. The fifth animal in the study suffered from intermediate episodes of vomiting and diarrhea during the monitoring period and exhibited remarkably more change (39.4%). This observation may reflect the temporary impact of perturbations such as the animal’s compromised health, antibiotic administration or a combination thereof, which temporarily altered the relative proportions of Clostridium clusters I and XIVa. In conclusion, this first long-term monitoring study of the faecal microbiota in feline strict carnivores not only reveals a remarkable compositional stability of this ecosystem, but also shows a qualitative and quantitative similarity in a defined set of faecal bacterial lineages across the five animals under

  11. Integrated community profiling indicates long-term temporal stability of the predominant faecal microbiota in captive cheetahs.

    PubMed

    Becker, Anne A M J; Janssens, Geert P J; Snauwaert, Cindy; Hesta, Myriam; Huys, Geert

    2015-01-01

    Understanding the symbiotic relationship between gut microbes and their animal host requires characterization of the core microbiota across populations and in time. Especially in captive populations of endangered wildlife species such as the cheetah (Acinonyx jubatus), this knowledge is a key element to enhance feeding strategies and reduce gastrointestinal disorders. In order to investigate the temporal stability of the intestinal microbiota in cheetahs under human care, we conducted a longitudinal study over a 3-year period with bimonthly faecal sampling of 5 cheetahs housed in two European zoos. For this purpose, an integrated 16S rRNA DGGE-clone library approach was used in combination with a series of real-time PCR assays. Our findings disclosed a stable faecal microbiota, beyond intestinal community variations that were detected between zoo sample sets or between animals. The core of this microbiota was dominated by members of Clostridium clusters I, XI and XIVa, with mean concentrations ranging from 7.5-9.2 log10 CFU/g faeces and with significant positive correlations between these clusters (P<0.05), and by Lactobacillaceae. Moving window analysis of DGGE profiles revealed 23.3-25.6% change between consecutive samples for four of the cheetahs. The fifth animal in the study suffered from intermediate episodes of vomiting and diarrhea during the monitoring period and exhibited remarkably more change (39.4%). This observation may reflect the temporary impact of perturbations such as the animal's compromised health, antibiotic administration or a combination thereof, which temporarily altered the relative proportions of Clostridium clusters I and XIVa. In conclusion, this first long-term monitoring study of the faecal microbiota in feline strict carnivores not only reveals a remarkable compositional stability of this ecosystem, but also shows a qualitative and quantitative similarity in a defined set of faecal bacterial lineages across the five animals under

  12. The Stability of Rankings Derived from Composite Indicators: Analysis of the "IL Sole 24 Ore" Quality of Life Report

    ERIC Educational Resources Information Center

    Lun, G.; Holzer, D.; Tappeiner, G.; Tappeiner, U.

    2006-01-01

    The calculation of composite indicators and the derivation of respective rankings is a common method used to benchmark countries or regions. However, although the statistical robustness of these rankings is often criticised, they often still spark off heated political debate. Here, we assess the sensitivity of the province ranking published by the…

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

    PubMed

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

    2011-01-01

    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

  14. Improvement of a stability-indicating method by Quality-by-Design versus Quality-by-Testing: a case of a learning process.

    PubMed

    Hubert, C; Lebrun, P; Houari, S; Ziemons, E; Rozet, E; Hubert, Ph

    2014-01-01

    The understanding of the method is a major concern when developing a stability-indicating method and even more so when dealing with impurity assays from complex matrices. In the presented case study, a Quality-by-Design approach was applied in order to optimize a routinely used method. An analytical issue occurring at the last stage of a long-term stability study involving unexpected impurities perturbing the monitoring of characterized impurities needed to be resolved. A compliant Quality-by-Design (QbD) methodology based on a Design of Experiments (DoE) approach was evaluated within the framework of a Liquid Chromatography (LC) method. This approach allows the investigation of Critical Process Parameters (CPPs), which have an impact on Critical Quality Attributes (CQAs) and, consequently, on LC selectivity. Using polynomial regression response modeling as well as Monte Carlo simulations for error propagation, Design Space (DS) was computed in order to determine robust working conditions for the developed stability-indicating method. This QbD compliant development was conducted in two phases allowing the use of the Design Space knowledge acquired during the first phase to define the experimental domain of the second phase, which constitutes a learning process. The selected working condition was then fully validated using accuracy profiles based on statistical tolerance intervals in order to evaluate the reliability of the results generated by this LC/ESI-MS stability-indicating method. A comparison was made between the traditional Quality-by-Testing (QbT) approach and the QbD strategy, highlighting the benefit of this QbD strategy in the case of an unexpected impurities issue. On this basis, the advantages of a systematic use of the QbD methodology were discussed. PMID:24176744

  15. A modeling approach to estimate the solar disinfection of viral indicator organisms in waste stabilization ponds and surface waters.

    PubMed

    Kohn, Tamar; Mattle, Michael J; Minella, Marco; Vione, Davide

    2016-01-01

    Sunlight is known to be a pertinent factor governing the infectivity of waterborne viruses in the environment. Sunlight inactivates viruses via endogenous inactivation (promoted by absorption of solar light in the UVB range by the virus) and exogenous processes (promoted by adsorption of sunlight by external chromophores, which subsequently generate inactivating reactive species). The extent of inactivation is still difficult to predict, as it depends on multiple parameters including virus characteristics, solution composition, season and geographical location. In this work, we adapted a model typically used to estimate the photodegradation of organic pollutants, APEX, to explore the fate of two commonly used surrogates of human viruses (coliphages MS2 and ϕX174) in waste stabilization pond and natural surface water. Based on experimental data obtained in previous work, we modeled virus inactivation as a function of water depth and composition, as well as season and latitude, and we apportioned the contributions of the different inactivation processes to total inactivation. Model results showed that ϕX174 is inactivated more readily than MS2, except at latitudes >60°. ϕX174 inactivation varies greatly with both season (20-fold) and latitude (10-fold between 0 and 60°), and is dominated by endogenous inactivation under all solution conditions considered. In contrast, exogenous processes contribute significantly to MS2 inactivation. Because exogenous inactivation can be promoted by longer wavelengths, which are less affected by changes in season and latitude, MS2 exhibits smaller fluctuations in inactivation throughout the year (10-fold) and across the globe (3-fold between 0 and 60°) compared to ϕX174. While a full model validation is currently not possible due to the lack of sufficient field data, our estimated inactivation rates corresponded well to those reported in field studies. Overall, this study constitutes a step toward estimating microbial water

  16. Comparison of Stability-Indicating LC Methods Using Light Scattering and Photodiode Array Detection with Monolithic Column for Determination of Quinapril and Hydrochlorothiazide.

    PubMed

    de Diego, Marta; Godoy, Ricardo; Mennickent, Sigrid; Vergara, Carola; Charnock, Henry; Hernández, Camilo

    2016-09-01

    Rapid stability-indicating LC methods for simultaneous analysis of quinapril and hydrochlorothiazide were developed, validated and compared using evaporative light scattering detection (ELSD) and diode array detection (DAD). For the separation of quinapril, hydrochlorothiazide and its major degradation products, a monolithic column was used and the analytes were eluted within 7 min, applying gradient mobile phase in both methods. Quinapril was subjected to hydrolytic, oxidative, thermal, humidity and photolytic stress conditions. Degradation products were well resolved from main peaks and from each other, proving the stability-indicating power of the methods. The response with DAD was linear and the response with ELSD was fitted to a power function, for quinapril and hydrochlorothiazide concentrations of 20-160 and 12.5-100 µg mL(-1), respectively. DAD method achieved better precision than ELSD method, the LOQ of DAD was lower and the accuracy of the methods was similar. Quinapril degrade by hydrolysis and thermal stress, showing the formation of quinaprilat and quinapril diketopiperazine as degradants, which were identified by MS-MS. The methods were successfully applied to quantify quinapril and hydrochlorothiazide in commercial tablets. LC-DAD and LC-ELSD methods are suitable to assess the stability and routine analysis of quinapril and hydrochlorothiazide in pharmaceutical industry. PMID:27165572

  17. 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

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

    2007-07-20

    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

  18. Engineering deamidation-susceptible asparagines leads to improved stability to thermal cycling in a lipase

    PubMed Central

    Bhanuramanand, K; Ahmad, Shoeb; Rao, N M

    2014-01-01

    At high temperatures, protein stability is influenced by chemical alterations; most important among them is deamidation of asparagines. Deamidation kinetics of asparagines depends on the local sequence, solvent, pH, temperature, and the tertiary structure. Suitable replacement of deamidated asparagines could be a viable strategy to improve deamidation-mediated loss in protein properties, specifically protein thermostability. In this study, we have used nano RP-HPLC coupled ESI MS/MS approach to identify residues susceptible to deamidation in a lipase (6B) on heat treatment. Out of 15 asparagines and six glutamines in 6B, only five asparagines were susceptible to deamidation at temperatures higher than 75°C. These five positions were subjected to site saturation mutagenesis followed by activity screen to identify the most suitable substitutions. Only three of the five asparagines were found to be tolerant to substitutions. Best substitutions at these positions were combined into a mutant. The resultant lipase (mutC) has near identical secondary structure and improved thermal tolerance as compared to its parent. The triple mutant has shown almost two-fold higher residual activity compared to 6B after four cycles at 90°C. MutC has retained more than 50% activity even after incubation at 100°C. Engineering asparagines susceptible to deamidation would be a potential strategy to improve proteins to withstand very high temperatures. PMID:25043738

  19. Advanced stability indicating chemometric methods for quantitation of amlodipine and atorvastatin in their quinary mixture with acidic degradation products

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    Two advanced, accurate and precise chemometric methods are developed for the simultaneous determination of amlodipine besylate (AML) and atorvastatin calcium (ATV) in the presence of their acidic degradation products in tablet dosage forms. The first method was Partial Least Squares (PLS-1) and the second was Artificial Neural Networks (ANN). PLS was compared to ANN models with and without variable selection procedure (genetic algorithm (GA)). For proper analysis, a 5-factor 5-level experimental design was established resulting in 25 mixtures containing different ratios of the interfering species. Fifteen mixtures were used as calibration set and the other ten mixtures were used as validation set to validate the prediction ability of the suggested models. The proposed methods were successfully applied to the analysis of pharmaceutical tablets containing AML and ATV. The methods indicated the ability of the mentioned models to solve the highly overlapped spectra of the quinary mixture, yet using inexpensive and easy to handle instruments like the UV-VIS spectrophotometer.

  20. Advanced stability indicating chemometric methods for quantitation of amlodipine and atorvastatin in their quinary mixture with acidic degradation products.

    PubMed

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

    2016-02-01

    Two advanced, accurate and precise chemometric methods are developed for the simultaneous determination of amlodipine besylate (AML) and atorvastatin calcium (ATV) in the presence of their acidic degradation products in tablet dosage forms. The first method was Partial Least Squares (PLS-1) and the second was Artificial Neural Networks (ANN). PLS was compared to ANN models with and without variable selection procedure (genetic algorithm (GA)). For proper analysis, a 5-factor 5-level experimental design was established resulting in 25 mixtures containing different ratios of the interfering species. Fifteen mixtures were used as calibration set and the other ten mixtures were used as validation set to validate the prediction ability of the suggested models. The proposed methods were successfully applied to the analysis of pharmaceutical tablets containing AML and ATV. The methods indicated the ability of the mentioned models to solve the highly overlapped spectra of the quinary mixture, yet using inexpensive and easy to handle instruments like the UV-VIS spectrophotometer. PMID:26513228

  1. Improved efficiency and stability of secnidazole - An ideal delivery system.

    PubMed

    Khan, Salman; Haseeb, Mohd; Baig, Mohd Hassan; Bagga, Paramdeep Singh; Siddiqui, H H; Kamal, M A; Khan, Mohd Sajid

    2015-01-01

    Secnidazole (α,2-Dimethyl-5-nitro-1H-imidazole-1-ethanol) is a highly effective drug against a variety of G(+)/G(-) bacteria but with significant side effects because it is being used in very high concentration. In this study, gold nanoparticles (GNPS) were selected as a vehicle to deliver secnidazole drug at the specific site with more accuracy which made the drug highly effective at substantially low concentrations. The as-synthesized GNPs were capped with Human Serum Albumin (HSA) and subsequently bioconjugated with secnidazole because HSA provides the stability and improves the solubility of the bioconjugated drug, secnidazole. The quantification of covalently bioconjugated secnidazole with HSA encapsulated on enzymatically synthesized GNPs was done with RP-HPLC having SPD-20 A UV/VIS detector by using the C-18 column. The bioconjugation of GNPs with secnidazole was confirmed by Transmission Electron Microscopy (TEM) and Dynamic Light Scattering (DLS). The bioconjugated GNPs were characterized by UV-VIS spectroscopy, TEM, Scanning Electron Microscopy (SEM) and DLS. Zeta potential confirmed the stability and uniform distribution of particles in the emulsion of GNPs. The separation of bioconjugated GNPs, unused GNPs and unused drug was done by gel filtration chromatography. The minimal inhibitory concentration of secnidazole-conjugated gold nanoparticles (Au-HSA-Snd) against Klebsiella pneumonia (NCIM No. 2957) and Bacillus cereus (NCIM No. 2156) got improved by 12.2 times and 14.11 times, respectively, in comparison to pure secnidazole. Precisely, the MIC of Au-HSA-Snd against K. pneumonia (NCIM No. 2957) and B. cereus (NCIM No. 2156) were found to be 0.35 and 0.43 μg/ml, respectively whereas MIC of the pure secnidazole drug against the same bacteria were found to be 4.3 and 6.07 μg/ml, respectively. PMID:25561882

  2. Development and validation of a stability-indicating LC-UV method for the determination of pantethine and its degradation product based on a forced degradation study.

    PubMed

    Canavesi, Rossana; Aprile, Silvio; Varese, Elena; Grosa, Giorgio

    2014-08-01

    Pantethine (d-bis-(N-pantothenyl-β-aminoethyl)-disulfide, PAN), the stable disulfide form of pantetheine, has beneficial effects in vascular diseases being able to decrease the hyperlipidaemia, moderate the platelet function and prevent the lipid peroxidation. Furthermore, recent studies suggested that PAN may be an effective therapeutic agent for cerebral malaria and, possibly, for neurodegenerative processes. Interestingly, in the literature, there were no data dealing with the chemical stability and the analytical aspects of PAN. Hence, in the present work the chemical stability of PAN was for the first time established through a forced degradation study followed by liquid chromatography tandem mass spectrometry investigation showing the formation of three degradation products of PAN (PD1, PD2 and POx) arising from hydrolytic, thermal and oxidative stresses. Based on these data a stability-indicating LC-UV method for simultaneous estimation of PAN, and its most relevant degradation product (PD1) was developed and validated; moreover the method allowed also the separation and the quantification of the preservative system, constituted by a paraben mixture. The method showed linearity for PAN (0.4-1.2mgmL(-1)), MHB, PHB (0.4-1.2μgmL(-1)) and PD1 (2.5-100μgmL(-1)); the precision, determined in terms of intra-day and inter-day precision, expressed as RSDs, were in the ranges 0.4-1.2 and 0.7-1.4, respectively. The method demonstrated to be accurate and robust; indeed the average recoveries were 100.2, 99.9, and 100.0% for PAN, MHB and PHB, respectively, and 99.9% for PD1. By applying small variations of the mobile phase composition, counter-ion concentration and pH the separation of analytes was not affected. Finally, the applicability of this method was evaluated analyzing the available commercial forms at release as well as during stability studies. PMID:24863372

  3. Heuman indices of hydrophobicity of bile acids and their comparison with a newly developed and conventional molecular descriptors.

    PubMed

    Poša, Mihalj

    2014-02-01

    Bile salts (BSs), in addition to their physiological role in the digestion of lipids in vertebrates, are also of significant importance in biomedical investigations. For predicting biological-pharmacological activity and physico-chemical properties of BSs it is important to develop such molecular descriptors that adequately describe the structural characteristics of the steroid skeleton. The present study encompassed the following bile acids (BAs): cholic, chenodeoxycholic, deoxycholic, hyodeoxycholic, ursodeoxycholic, hyocholic, and ursocholic acid, as well as oxo derivatives of certain BAs. For all of them, Heuman hydrophobicity indices (HI(BA)) (RP-HPLC parameters) were determined, and a detailed conformational analysis of the steroid skeleton showed that HI(BA) has the discrimination power for BAs based on the size of the hydrophobic surface on the β side and the lateral L7 and L12 sides of the steroid skeleton. Also, HI(BA) discerns the regiochemical characteristics of OH and oxo groups. Based on a survey of the structural factors of the steroid skeleton that influence the HI(BA) values of the tested BAs, we constructed a new molecular descriptor, CHIBA, with the characteristics of 2D and 3D topological descriptors. In respect of the structure of the steroid skeleton, the descriptor CHIBA behaves as a reversed-phase chromatographic descriptor of BAs. PMID:24076126

  4. Stability-indicating capillary zone electrophoresis method for the assessment of recombinant human interleukin-11 and its correlation with reversed-phase liquid chromatography and biossay.

    PubMed

    Souto, Ricardo Bizogne; Stamm, Fernanda Pavani; Schumacher, Jéssica Barbieri; Cardoso, Clovis Dervil Appratto; de Freitas, Guilherme Weber; Perobelli, Rafaela Ferreira; Dalmora, Sérgio Luiz

    2014-06-01

    A stability-indicating capillary zone electrophoresis (CZE) method was validated for the analysis of recombinant human interleukin-11(rhIL-11) using rupatadine fumarate, as internal standard (IS). A fused-silica capillary, (50 µm i.d.; effective length, 40 cm) was used at 25°C; the applied voltage was 20 kV. The background electrolyte solution consisted of 50 mmol L(-1) sodium dihydrogen phosphate solution at pH 3.0. Injections were performed using a pressure mode at 50 mbar for 45 s, with detection by photodiode array detector set at 196 nm. Specificity and stability-indicating capability were established in degradation studies, which also showed that there was no interference of the excipients. The method was linear over the concentration range of 1.0-300 µg mL(-1) (r(2)=0.9992) and the limit of detection (LOD) and limit of quantitation (LOQ) were 0.2 µg mL(-1) and 1.0 µg mL(-1), respectively. The accuracy was 100.4% with bias lower than 1.1%. Moreover, the in vitro cytotoxicity test of the degraded products showed significant differences (p<0.05). The method was applied for the content/potency assessment of rhIL-11 in biopharmaceutical formulations, and the results were correlated to those of a validated reversed-phase LC method (RP-LC) and an TF-1 cell culture assay, showing non-significant differences (p>0.05). In addition the CZE and RP-LC methods were applied for the analysis of rhIL-11 in human plasma. Therefore, the proposed alternative method can be applied to monitor stability, to assure the batch-to-batch consistency and quality of the bulk and finished biotechnology-derived medicine. PMID:24725881

  5. Stability-indicating UHPLC method for determination of nevirapine in its bulk form and tablets: identification of impurities and degradation kinetic study.

    PubMed

    Reis, Naialy Fernandes Araújo; de Assis, Jéssica Camille; Fialho, Sílvia Ligório; Pianetti, Gerson Antônio; Fernandes, Christian

    2016-07-15

    Nevirapine (NVP), a non-nucleoside reverse transcriptase inhibitor, is a drug widely used in the treatment of Acquired Immunodeficiency Syndrome (AIDS). The evaluation of NVP stability is of fundamental importance in order to guarantee drug product efficacy, safety and quality. In this study, NVP active pharmaceutical ingredient (API) and tablets were subjected to a detailed study of forced degradation, employing several degrading agents (acid, alkaline, water, metal ions, humidity, heat, light and oxidation agents). In order to determine NVP and the degradation products formed, a stability-indicating UHPLC method using fused core column was developed and validated. The separation was carried out using a Poroshell 120C18 column (100×2.1mm i.d.; 2.7μm particle size) and the mobile phase was composed of acetonitrile and water in a gradient elution, at a flow rate of 0.2ml/min. Chemical structures and mechanisms for the formation of three degradation products were proposed by means of LC/MS-MS. Also, NVP degradation kinetic was studied and its order of degradation evaluated. NVP was degraded in acidic and oxidative conditions and the degradation profile for NVP tablets and API were similar. The stability-indicating method proved to be selective for NVP and its degradation products. Calibration curve was linear in the range of 8-48μg/ml and the method showed to be precise, accurate and robust for both NVP API and tablets, with detection and quantification limits of 0.092μg/ml and 0.174μg/ml, respectively. PMID:27179642

  6. Nifedipine-loaded polymeric nanocapsules: validation of a stability-indicating HPLC method to evaluate the drug entrapment efficiency and in vitro release profiles.

    PubMed

    Granada, Andréa; Tagliari, Monika Piazzon; Soldi, Valdir; Silva, Marcos António Segatto; Zanetti-Ramos, Betina Ghiel; Fernandes, Daniel; Stulzer, Hellen Karine

    2013-01-01

    A simple stability-indicating analytical method was developed and validated to quantify nifedipine in polymeric nanocapsule suspensions; an in vitro drug release study was then carried out. The analysis was performed using an RP C18 column, UV-Vis detection at 262 nm, and methanol-water (70 + 30, v/v) mobile phase at a flow rate of 1.2 mL/min. The method was validated in terms of specificity, linearity and range, LOQ, accuracy, precision, and robustness. The results obtained were within the acceptable ranges. The nanocapsules, made of poly(epsilon-caprolactone), were prepared by the solvent displacement technique and showed high entrapment efficiency. The entrapment efficiency was 97.6 and 98.2% for the nifedipine-loaded polymeric nanocapsules prepared from polyvinyl alcohol (PVA) and Pluronic F68 (PF68), respectively. The particle size and zeta potential of nanocapsules were found to be influenced by the nature of the stabilizer used. The mean diameter and zeta potential for nanocapsules with PVA and PF68 were 290.9 and 179.9 nm, and -17.7 mV and -32.7 mV, respectively. The two formulations prepared showed a drug release of up to 70% over 4 days. This behavior indicates the viability of this drug delivery system for use as a controlled-release system. PMID:23767350

  7. 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

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

    2012-12-01

    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 μm 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

  8. Validation of a Stability-Indicating Hydrophilic Interaction Liquid Chromatographic Method for the Quantitative Determination of Vitamin K3 (Menadione Sodium Bisulfite) in Injectable Solution Formulation

    PubMed Central

    Ghanem, Mashhour M.; Abu-Lafi, Saleh A.; Hallak, Hussein O.

    2013-01-01

    A simple, specific, accurate, and stability-indicating method was developed and validated for the quantitative determination of menadione sodium bisulfite in the injectable solution formulation. The method is based on zwitterionic hydrophilic interaction liquid chromatography (ZIC-HILIC) coupled with a photodiode array detector. The desired separation was achieved on the ZIC-HILIC column (250 mm × 4.6 mm, 5 μm) at 25°C temperature. The optimized mobile phase consisted of an isocratic solvent mixture of 200mM ammonium acetate (NH4AC) solution and acetonitrile (ACN) (20:80; v/v) pH-adjusted to 5.7 by glacial acetic acid. The mobile phase was fixed at 0.5 ml/min and the analytes were monitored at 261 nm using a photodiode array detector. The effects of the chromatographic conditions on the peak retention, peak USP tailing factor, and column efficiency were systematically optimized. Forced degradation experiments were carried out by exposing menadione sodium bisulfite standard and the injectable solution formulation to thermal, photolytic, oxidative, and acid-base hydrolytic stress conditions. The degradation products were well-resolved from the main peak and the excipients, thus proving that the method is a reliable, stability-indicating tool. The method was validated as per ICH and USP guidelines (USP34/NF29) and found to be adequate for the routine quantitative estimation of menadione sodium bisulfite in commercially available menadione sodium bisulfite injectable solution dosage forms. PMID:24106670

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

    PubMed

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

    2011-09-01

    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 μm (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

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

    PubMed Central

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

    2011-01-01

    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 μm (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

  11. Development and Validation of a Stability-Indicating RP-UPLC Method for the Estimation of Impurities in Cinacalcet Hydrochloride API and its Formulation.

    PubMed

    Sunil Reddy, Pingili; Raju, Thummala Veera Raghava; Raju, Penmetsa Satyanarayana; Varma, Nadimpalli Sunil; Babu, Kondra Sudhakar

    2015-01-01

    A sensitive, stability-indicating, gradient reversed-phase ultra-performance liquid chromatography method has been developed for the quantitative estimation of cinacalcet hydrochloride impurities in active pharmaceutical ingredients and pharmaceutical formulations. Efficient chromatographic separation was achieved on an Acquity BEH Shield RP18, 100 × 2.1 mm, 1.7 µm column with the mobile phase containing pH 6.6 phosphate buffer and acetonitrile. The flow rate of the mobile phase was 0.3 mL min(-1) with a column temperature of 35°C and detection wavelength at 223 nm. The relative response factor values of (+)-R-1-(1-Naphthyl)ethylamine, regioisomer, diastereomer isomer-1, and diastereomer isomer-2 were 1.79, 0.99, 0.89, and 0.88, respectively. The cinacalcet hydrochloride formulation sample was subjected to the stress conditions of acid, base, oxidative, hydrolytic, thermal, humidity, and photolytic degradation. Cinacalcet hydrochloride was found to degrade significantly under the peroxide stress conditions. The degradation products were well-resolved from cinacalcet hydrochloride and its impurities. The peak purity test results confirmed that the cinacalcet hydrochloride peak was homogenous in all stress samples and the mass balance was found to be more than 96%, thus proving the stability-indicating power of the method. The developed method was validated according to ICH guidelines. PMID:26839840

  12. Quantitative determination of the β-methyl carbapenem doripenem in powder for injection by a stability-indicating capillary zone electrophoresis method.

    PubMed

    Paliosa, P K; Garcia, C V; Schapoval, E E S; Mendez, A S L; Steppe, M

    2015-09-01

    A capillary zone electrophoresis method for quantitative determination of doripenem in synthetic matrix was developed. The stability-indicating capability was performed applying stress testing protocols. The selected analytical conditions include 100 mM sodium borate buffer (pH 8.0) as run electrolyte, voltage of +15 kV, hydrodynamic injection of 5s (50 mBar), detection at 298 nm and temperature of analysis of 25 degrees C. The electrophoretic separation was carried out in a fused silica capillary (effective length 40 cm, 50 μm i.d.), using procainamide hydrochloride as internal standard. The proposed method showed quickness and reproducibility, with an analytical run in a total time of 5 min. The percentage of drug amount estimated was 101.33% (RSD = 0.80), with satisfactory intra-day and inter-day precision. In the recovery test, the method was found to be reliable and accurate in the drug quantitation (mean recovery = 101.86%). The robustness was performed applying the Plackett-Burman experimental design which confirmed the assay reliability. Based on results from forced degradation study, the stability-indicating capability was established, being observed a major degradation in alkaline, photolytic and thermal conditions. In comparison to HPLC method previously developed, the proposed capillary electrophoresis assay is statistically equivalent. PMID:26492640

  13. Development and Validation of a Stability-Indicating RP-UPLC Method for the Estimation of Impurities in Cinacalcet Hydrochloride API and its Formulation

    PubMed Central

    Sunil Reddy, Pingili; Raju, Thummala Veera Raghava; Raju, Penmetsa Satyanarayana; Varma, Nadimpalli Sunil; Babu, Kondra Sudhakar

    2015-01-01

    A sensitive, stability-indicating, gradient reversed-phase ultra-performance liquid chromatography method has been developed for the quantitative estimation of cinacalcet hydrochloride impurities in active pharmaceutical ingredients and pharmaceutical formulations. Efficient chromatographic separation was achieved on an Acquity BEH Shield RP18, 100 × 2.1 mm, 1.7 µm column with the mobile phase containing pH 6.6 phosphate buffer and acetonitrile. The flow rate of the mobile phase was 0.3 mL min−1 with a column temperature of 35°C and detection wavelength at 223 nm. The relative response factor values of (+)-R-1-(1-Naphthyl)ethylamine, regioisomer, diastereomer isomer-1, and diastereomer isomer-2 were 1.79, 0.99, 0.89, and 0.88, respectively. The cinacalcet hydrochloride formulation sample was subjected to the stress conditions of acid, base, oxidative, hydrolytic, thermal, humidity, and photolytic degradation. Cinacalcet hydrochloride was found to degrade significantly under the peroxide stress conditions. The degradation products were well-resolved from cinacalcet hydrochloride and its impurities. The peak purity test results confirmed that the cinacalcet hydrochloride peak was homogenous in all stress samples and the mass balance was found to be more than 96%, thus proving the stability-indicating power of the method. The developed method was validated according to ICH guidelines. PMID:26839840

  14. Development and validation of stability-indicating TLC-densitometric method for determination of betaxolol with LC-ESI/MS analysis of degradation product.

    PubMed

    Kwiecień, Anna; Krzek, Jan; Walczak, Maria; Mazur, Mateusz

    2013-01-01

    The purpose of this work was to develop a sensitive stability indicating TLC-densitometric method for the determination of betaxolol (Bx) in pharmaceutical preparations and to study the stability of Bx in acidic solutions. The method was developed on TLC aluminium plates precoated with silica gel F254using the mobile phase chloroform-methanol-ammonia 25% (18 : 4: 0.2, v/v/v) which gives compact spots for Bx (R(f) approximately equal to 0.64) and its degradation product (R(f) approximately equal to 0.39). Densitometric analysis was carried out in UV at 280 nm. The developed method is highly sensitive (LOD = 66.6 ng/spot, LOQ = 200 ng/spot), precise (RSD = 2.73%) and accurate (mean recovery = 100.28% at 100% level). Bx was subjected to acidic and alkaline hydrolysis but degradation was observed only in acidic solutions. The degradation process was described with kinetic and thermodynamic parameters. Based on LC-ESI/MS analysis, it was found that Bx decomposes in acidic solution to produce ethoxyphenoxy-3-[(1-methylethyl)amino]propan-2-ol. PMID:23923388

  15. Characterization of a potential medium for 'biorelevant' in vitro release testing of a naltrexone implant, employing a validated stability-indicating HPLC method.

    PubMed

    Iyer, Sunil S; Barr, William H; Karnes, H Thomas

    2007-02-19

    A variety of factors have been recognized that influence media optimization for drug release studies of implant dosage forms. Of primary importance is selection of a medium that physiologically mimics the milieu at the site of administration (a condition termed 'biorelevance'). We describe in this paper, the characterization of Hanks' balanced salts solution, with necessary modification, for application as a 'biorelevant' medium for in vitro release studies of a biodegradable, subcutaneous implant of naltrexone. A detailed investigation of changes in pH, osmolality and ultraviolet (UV) spectrum as a function of time and temperature was conducted. Variation in the parameters evaluated was found to be within acceptable limits. Validation of a simple and selective, high performance liquid chromatography (HPLC) assay method for naltrexone was carried out to evaluate stability. The calibration curves were linear from 0.16 to 20.00 microg ml(-1). Imprecision and inaccuracy were less than 2% and no interference was observed from degradation peaks. Stability studies of naltrexone indicated the media should be replaced every 7-8 days for real-time testing. This was applied to an investigation of in vitro drug release. The method has been proven to be suitable for investigation of naltrexone released from the implant. PMID:17045445

  16. A Stability-Indicating HPLC-DAD Method for Determination of Ferulic Acid into Microparticles: Development, Validation, Forced Degradation, and Encapsulation Efficiency.

    PubMed

    Nadal, Jessica Mendes; Toledo, Maria da Graça; Pupo, Yasmine Mendes; Padilha de Paula, Josiane; Farago, Paulo Vitor; Zanin, Sandra Maria Warumby

    2015-01-01

    A simple stability-indicating HPLC-DAD method was validated for the determination of ferulic acid (FA) in polymeric microparticles. Chromatographic conditions consisted of a RP C18 column (250 mm × 4.60 mm, 5 μm, 110 Å) using a mixture of methanol and water pH 3.0 (48 : 52 v/v) as mobile phase at a flow rate of 1.0 mL/min with UV detection at 320 nm. The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of quantification, limit of detection, accuracy, precision, and robustness provided suitable results regarding all parameters investigated. The calibration curve was linear in the concentration range of 10.0-70.0 μg/mL with a correlation coefficient >0.999. Precision (intraday and interday) was demonstrated by a relative standard deviation lower than 2.0%. Accuracy was assessed by the recovery test of FA from polymeric microparticles (99.02% to 100.73%). Specificity showed no interference from the components of polymeric microparticles or from the degradation products derived from acidic, basic, and photolytic conditions. In conclusion, the method is suitable to be applied to assay FA as bulk drug and into polymeric microparticles and can be used for studying its stability and degradation kinetics. PMID:26075139

  17. 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 Central

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

    2013-01-01

    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 μ) 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 μg/ml for ketorolac tromethamine, 20.8-62.4 μg/ml for sodium methylparaben and 2.38-7.13 μg/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

  18. Analytical Quality by Design Approach in RP-HPLC Method Development for the Assay of Etofenamate in Dosage Forms

    PubMed Central

    Peraman, R.; Bhadraya, K.; Reddy, Y. Padmanabha; Reddy, C. Surayaprakash; Lokesh, T.

    2015-01-01

    By considering the current regulatory requirement for an analytical method development, a reversed phase high performance liquid chromatographic method for routine analysis of etofenamate in dosage form has been optimized using analytical quality by design approach. Unlike routine approach, the present study was initiated with understanding of quality target product profile, analytical target profile and risk assessment for method variables that affect the method response. A liquid chromatography system equipped with a C18 column (250×4.6 mm, 5 μ), a binary pump and photodiode array detector were used in this work. The experiments were conducted based on plan by central composite design, which could save time, reagents and other resources. Sigma Tech software was used to plan and analyses the experimental observations and obtain quadratic process model. The process model was used for predictive solution for retention time. The predicted data from contour diagram for retention time were verified actually and it satisfied with actual experimental data. The optimized method was achieved at 1.2 ml/min flow rate of using mobile phase composition of methanol and 0.2% triethylamine in water at 85:15, % v/v, pH adjusted to 6.5. The method was validated and verified for targeted method performances, robustness and system suitability during method transfer. PMID:26997704

  19. Determination of rifaximin in rat serum by ionic liquid based dispersive liquid-liquid microextraction combined with RP-HPLC.

    PubMed

    Rao, Ramisetti Nageswara; Vali, Rajavarapu Mastan; Rao, Alamanda Vara Prasada

    2012-08-01

    An efficient and environmental friendly ionic liquid based dispersive liquid-liquid microextraction procedure was optimized for determination of rifaximin in rat serum by reverse phase high-performance liquid chromatography. The effect of ionic liquids, dispersive solvents, extractant/disperser ratio, and salt concentrations on sample recovery and enrichment factors were studied. Among the five ionic liquids studied in the present investigation, 1-butyl-3-methylimidazolium hexafluorophosphate was found to be most effective for extraction of rifaximin. The recovery was found to be more than 98% using 1-butyl-3-methylimidazolium hexafluorophosphate and methanol as extraction and dispersive solvents, at an extractant/disperser ratio of 0.43. The recovery was further enhanced to 99.5% by the addition of 5.0% NaCl solution. A threefold enhancement in detection limit was achieved when compared to protein precipitation. The ionic liquid containing the extracted rifaximin was directly injected into HPLC system. The linear relationship was observed in the range of 0.03-10.0 μg/mL with the correlation coefficient (r(2)) 0.9998. Limits of detection and quantification were found to be 0.01 and 0.03 μg/mL, respectively. The relative standard deviation was 2.5%. The method was validated and applied to study pharmacokinetics of rifaxmin in rat serum. PMID:22753340

  20. Simplified RP-HPLC method for multi-residue analysis of abamectin, emamectin benzoate and ivermectin in rice.

    PubMed

    Xie, Xianchuan; Gong, Shu; Wang, Xiaorong; Wu, Yinxing; Zhao, Li

    2011-01-01

    A rapid, reliable and sensitive reverse-phase high-performance liquid chromatography method with fluorescence detection (RP-FLD-HPLC) was developed and validated for simultaneous analysis of the abamectin (ABA), emamectin (EMA) benzoate and ivermectin (IVM) residues in rice. After extraction with acetonitrile/water (2 : 1) with sonication, the avermectin (AVMs) residues were directly derivatised by N-methylimidazole (N-NMIM) and trifluoroacetic anhydride (TFAA) and then analysed on RP-FLD-HPLC. A good linear relationship (r(2 )> 0.99) was obtained for three AVMs ranging from 0.01 to 5 microg ml(-1), i.e. 0.01-5.0 microg g(-1) in rice matrix. The limit of detection (LOD) and the limit of quantification (LOQ) were between 0.001 and 0.002 microg g(-1) and between 0.004 and 0.006 microg g(-1), respectively. Recoveries were from 81.9% to 105.4% and precision less than 12.4%. The proposed method was successfully applied to routine analysis of the AVMs residues in rice. PMID:21132591

  1. Quality by Design Approach for Simultaneous Estimation of Doxycycline Hyclate and Curcumin by RP-HPLC Method

    PubMed Central

    Dhal, C.; Ahmad, F. J.; Chauhan, A.; Jyothi, M.; Singh, R. M.; Saini, P. K.; Mathur, S. C.; Singh, G. N.

    2015-01-01

    A simple, rapid, reliable, robust and optimized reversed phase high performance liquid chromatographic method for simultaneous estimation of doxycycline hyclate and curcumin was successfully developed and validated as per International Conference on Harmonization guidelines. The objective was achieved in terms of well separated peaks within 10 min on a Waters Sunfire C8 column with dimensions of 250×4.6 mm, particle size 5.0 μm using mobile phase consisting of 30 volumes of potassium dihydrogen phosphate buffer (50 mM) adjusted to pH 6.5±0.1 with triethylamine and 70 volumes of methanol at flow rate of 0.85 ml/min. The column effluents were monitored at 400 nm maintained at ambient column temperature (28o). The developed method was found linear over the concentration range of 200-700 μg/ml for doxycycline hyclate and 8-28 μg/ml for curcumin, the detection and quantitation limit was found to be 26.063 and 78.97 μg/ml for doxycycline hyclate; 0.795 and 2.13 μg/ml for curcumin, respectively. The developed method was optimized using Minitab software version 16 to meet the current quality by design requirements. The method validation was done for linearity, range, detection and quantitation limit, accuracy, precision, specificity, system suitability testing, and robustness. PMID:26997700

  2. RP-HPLC analysis of phenolic compounds and flavonoids in beverages and plant extracts using a CoulArray detector.

    PubMed

    Jandera, Pavel; Skeifíková, Veronika; Rehová, Lucie; Hájek, Tomás; Baldriánová, Lucie; Skopová, Gabriela; Kellner, Vladimír; Horna, Ales

    2005-06-01

    Methods were developed for the analysis of natural antioxidants including phenolic compounds and flavonoids in beverages and plant extracts using gradient HPLC with multi-channel electrochemical coulometric detection. Suitability of various reversed-phase columns for this purpose was compared; pH and mobile phase gradients were optimized with respect to the separation selectivity and sensitivity of detection. Because of different target compounds in various sample types, the overlapping resolution maps and the normalized resolution product approaches described earlier were used to select optimum columns and gradients to suit the analysis of the individual sample types. The methods were applied to the analysis of phenolic compounds and flavonoids in beer, wine, tea, and yacon extracts. 32 phenolic compounds were identified and determined, including derivatives of benzoic and cinnamic acids, flavones, and a few related glycosides. Eight-channel CoulArray detection offers high selectivity and sensitivity with limits of detection in the low microg L(-1) range, at least an order of magnitude lower than single-channel coulometric detection using the Coulochem detector. No special sample pretreatment is necessary and, because of the compatibility of the CoulArray detector with gradient elution, phenolic antioxidants of different polarities can be determined in a single run. In addition to the retention times, the ratios of the areas of the pre-dominant and post-dominant peaks to the area of the dominant peak can be used for improved identification of natural antioxidants. PMID:16013828

  3. Comparison of RP-HPLC modes to analyse the N-glycome of the free-living nematode Pristionchus pacificus

    PubMed Central

    Yan, Shi; Wilson, Iain B. H.; Paschinger, Katharina

    2015-01-01

    Pristionchus pacificus is a free-living nematode increasingly used as an organism for comparison to the more familiar model Caenorhabditis elegans. In this study, we examined the N-glycans of this organism isolated after serial release with peptide:N-glycosidases F and A; after fluorescent labelling with 2-aminopyridine, chromatographic fractionation by three types of reversed-phase HPLC (with either classical C18, fused core C18 or alkylamide bonded phases) followed by mass spectrometric analyses revealed key features of its N-glycome. In addition to paucimannosidic and oligomannosidic glycans typical of invertebrates, N-glycans with two core fucose residues were detected. Furthermore, a range of glycans carrying up to three phosphorylcholine residues was observed whereas, unlike C. elegans, no tetrafucosylated N-glycans were detected. Structures with three fucose residues, unusual methylation of core α1,3-fucose or with galactosylated fucose motifs were found in low amounts; these features may correlate with a different ensemble or expression of glycosyltransferase genes as compared to C. elegans. From an analytical perspective, both the alkylamide RP-amide and fused core C18 columns, as compared to a classical C18 material, offer advantages in terms of resolution and of elution properties, as some minor pyridylamino-labelled glycans (e.g., those carrying phosphorylcholine) appear in earlier fractions and so potential losses of such structures due to insufficient gradient length can be avoided. PMID:25639343

  4. Analytical Quality by Design Approach in RP-HPLC Method Development for the Assay of Etofenamate in Dosage Forms.

    PubMed

    Peraman, R; Bhadraya, K; Reddy, Y Padmanabha; Reddy, C Surayaprakash; Lokesh, T

    2015-01-01

    By considering the current regulatory requirement for an analytical method development, a reversed phase high performance liquid chromatographic method for routine analysis of etofenamate in dosage form has been optimized using analytical quality by design approach. Unlike routine approach, the present study was initiated with understanding of quality target product profile, analytical target profile and risk assessment for method variables that affect the method response. A liquid chromatography system equipped with a C18 column (250×4.6 mm, 5 μ), a binary pump and photodiode array detector were used in this work. The experiments were conducted based on plan by central composite design, which could save time, reagents and other resources. Sigma Tech software was used to plan and analyses the experimental observations and obtain quadratic process model. The process model was used for predictive solution for retention time. The predicted data from contour diagram for retention time were verified actually and it satisfied with actual experimental data. The optimized method was achieved at 1.2 ml/min flow rate of using mobile phase composition of methanol and 0.2% triethylamine in water at 85:15, % v/v, pH adjusted to 6.5. The method was validated and verified for targeted method performances, robustness and system suitability during method transfer. PMID:26997704

  5. Development and validation of a fast RP-HPLC method for the determination of clobetasol propionate in topical nanocapsule suspensions.

    PubMed

    Fontana, M C; Bastos, M O; Beck, R C R

    2010-09-01

    A simple and rapid high-performance liquid chromatographic method is validated for the determination of clobetasol propionate in topical nanocapsule suspensions. The method is carried out on an RP-18 column with a mobile phase composed of methanol-water (80:20 v/v) and UV detection at 241 nm. The method validation yields good results with respect to linearity, specificity, precision, accuracy, and robustness. The calibration curve in the range of 5.0-40.0 microg/mL shows a correlation coefficient of 0.9999. Precision (intra-day and inter-day) is demonstrated by a relative standard deviation lower than 1.5%. Accuracy is assessed by the recovery test of clobetasol propionate from sample matrixes (98.33 +/- 0.88%). In conclusion, the method is suitable to be applied to assay clobetasol propionate in topical formulations of polymeric nanocapsules, avoiding the use of a buffer solution in the mobile phase. PMID:20819292

  6. Validated RP-HPLC and HPTLC methods for determination of anti-inflammatory bis-indole alkaloid in Desmodium gangeticum.

    PubMed

    Yadav, Akhilesh K; Gupta, Madan M

    2014-01-01

    Here, two simple and accurate methods, namely high-performance liquid chromatography and high-performance thin-layer chromatography for the detection of gangenoid, an anti-inflammatory alkaloid, in a well-known Indian medicinal plant Desmodium gangeticum, are described. The proposed methods were successfully used for the estimation of gangenoid in D. gangeticum root. PMID:24079376

  7. Development and Validation of RP-HPLC Method for Simultaneous Estimation of Cefpodoxime Proxetil and Dicloxacillin Sodium in Tablets.

    PubMed

    Acharya, D R; Patel, Dipti B

    2013-01-01

    A simple, accurate, rapid and precise reversed-phase high-performance liquid chromatographic method has been developed and validated for simultaneous determination of cefpodoxime proxetil and dicloxacillin sodium in tablet. The chromatographic separation was carried out on kromasil C18 analytical column (250×4.6 mm; 5 μm) with a mixture of acetonitrile:methanol:trifloroacetic acid (0.001%) with pH 6.5 (30:50:20, v/v/v) as mobile phase; at a flow rate of 1.0 ml/min. UV detection was performed at 235 nm. The dicloxacillin sodium and cefpodoxime proxetil were eluted at 1.92 and 3.35 min, respectively. The peaks were eluted with better resolution. Calibration plots were linear over the concentration range 0.5-20 μg/ml for cefpodoxime proxetil (r(2)=0.9996) and 5-50 μg/ml for dicloxacillin sodium (r(2)=0.9987). The method was validated for accuracy, precision, linearity and specificity. The method was very sensitive with limit of detection 0.0726, 0.3685 μg/ml and limit of quantification 0.220, 1.116 μg/ml for cefpodoxime proxetil and dicloxacillin sodium, respectively. The high recovery and low relative standard deviation confirm the suitability of the method for routine determination of cefpodoxime proxetil and dicloxacillin sodium in bulk drug and tablet dosage form. PMID:23901158

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

    PubMed Central

    Giang, Do T; Hoang, Vu D

    2010-01-01

    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

  9. Development and Validation of RP-HPLC Method for Simultaneous Estimation of Cefpodoxime Proxetil and Dicloxacillin Sodium in Tablets

    PubMed Central

    Acharya, D. R.; Patel, Dipti B.

    2013-01-01

    A simple, accurate, rapid and precise reversed-phase high-performance liquid chromatographic method has been developed and validated for simultaneous determination of cefpodoxime proxetil and dicloxacillin sodium in tablet. The chromatographic separation was carried out on kromasil C18 analytical column (250×4.6 mm; 5 μm) with a mixture of acetonitrile:methanol:trifloroacetic acid (0.001%) with pH 6.5 (30:50:20, v/v/v) as mobile phase; at a flow rate of 1.0 ml/min. UV detection was performed at 235 nm. The dicloxacillin sodium and cefpodoxime proxetil were eluted at 1.92 and 3.35 min, respectively. The peaks were eluted with better resolution. Calibration plots were linear over the concentration range 0.5-20 μg/ml for cefpodoxime proxetil (r2=0.9996) and 5-50 μg/ml for dicloxacillin sodium (r2=0.9987). The method was validated for accuracy, precision, linearity and specificity. The method was very sensitive with limit of detection 0.0726, 0.3685 μg/ml and limit of quantification 0.220, 1.116 μg/ml for cefpodoxime proxetil and dicloxacillin sodium, respectively. The high recovery and low relative standard deviation confirm the suitability of the method for routine determination of cefpodoxime proxetil and dicloxacillin sodium in bulk drug and tablet dosage form. PMID:23901158

  10. RP-HPLC method for the quantitative analysis of naturally occurring flavonoids in leaves of Blumea balsamifera DC.

    PubMed

    Nessa, Fazilatun; Ismail, Zhari; Karupiah, Sundram; Mohamed, Nornisah

    2005-09-01

    A selective and sensitive reversed-phase (RP) high-performance liquid chromatographic method is developed for the quantitative analysis of five naturally occurring flavonoids of Blumea balsamifera DC, namely dihydroquercetin-7,4'-dimethyl ether (DQDE), blumeatin (BL), quercetin (QN), 5,7,3',5'-tetrahydroxyflavanone (THFE), and dihydroquercetin-4'-methyl ether (DQME). These compounds have been isolated using various chromatographic methods. The five compounds are completely separated within 35 min using an RP C18, Nucleosil column and with an isocratic methanol-0.5% phosphoric acid (50:50, v/v) mobile phase at the flow rate of 0.9 mL/min. The separation of the compounds is monitored at 285 nm using UV detection. Identifications of specific flavonoids are made by comparing their retention times with those of the standards. Reproducibility of the method is good, with coefficients of variation of 1.48% for DQME, 2.25% for THFE, 2.31% for QN, 2.23% for DQDE, and 1.51% for BL. The average recoveries of pure flavonoids upon addition to lyophilized powder and subsequent extraction are 99.8% for DQME, 99.9% for THFE, 100.0% for BL, 100.6% for DQDE, and 97.4% for QN. PMID:16212782

  11. Simultaneous Determination of Fangchinoline and Tetrandrine in Qi-Fang-Xi-Bi-Granules by RP-HPLC.

    PubMed

    Lu, XinGang; Zhang, RuoXi; Fu, Feng; Shen, Jie; Nian, Hua; Wu, Tao

    2015-09-01

    Knee Osteoarthritis is one of the most common diseases of elder worldwide. Qi-Fang-Xi-Bi-Granules (QFXBG) is a new Chinese medicine granules employed for the treatment of Knee Osteoarthritis. Fangchinoline (FAN) and tetrandrine (TET) are used as targets of quality control of QFXBG. A simple, practical high-performance liquid chromatographic method was developed for the simultaneous quantitation of FAN and TET in Stephaniae tetrandrae radix and QFXBG. The analysis was performed on a Athena C18 column (250 × 4.6 mm, 5 µm) with mobile phase of methanol-water (65 : 35, v/v, pH 3.0, adjusted by glacial acetic acid) containing 1.0 g/L sodium 1-octanesulfonate. This method was validated in terms of linearity, precision, accuracy and recovery. Results showed that this method had good linearity with R(2) at >0.999. The limit of detection and limit of quantification for FAN were 0.13 and 0.35 mg/L, while for TET were 0.28 and 0.76 mg/L, respectively. The relative standard deviations of precision were 0.1-1.3% for intraday and 0.5-2.4% for interday. The recovery was 94.56-98.81% of FAN and 94.07-99.12% of TET, respectively. The chromatographic analytical time was 14 min. This method was successfully applied for the quantitative analysis of FAN and TET in Stephaniae tetrandrae radix and QFXBG, so that it could be extended to quality control of QFXGB in commercial. PMID:25754692

  12. RP-HPLC method with electrochemical detection for the determination of metoclopramide in serum and its use in pharmacokinetic studies.

    PubMed

    Lamparczyk, H; Chmielewska, A; Konieczna, L; Plenis, A; Zarzycki, P K

    2001-12-01

    A rapid and sensitive reversed-phase high performance liquid chromatographic method has been developed for the determination of metoclopramide in serum. The assay was performed after single extraction with ethyl ether using methyl parahydroxybenzoate as internal standard. Chromatographic separations were performed on C(18) stationary phase with a mobile phase composed of methanol-phosphate buffer pH 3 (30:70 v/v). Analytes were detected electrochemically. The quantification limit for metoclopramide in serum was 2 ng mL(-1). Linearity of the method was confirmed in the range of 5-120 ng mL(-1) (correlation coefficient 0.9998). Within-day relative standard deviations (RSDs) ranged from 0.3 to 5.5% and between-day RSDs from 0.8 to 6.0%. The analytical method was successfully applied for the determination of pharmacokinetic parameters after ingestion of 10 mg dose of metoclopramide. Studies were performed on 18 healthy volunteers of both sexes. PMID:11748686

  13. A novel RP-HPLC method for the detection and quantification of roxithromycin in topical delivery studies.

    PubMed

    Aucamp, M E; Csongradi, C; Gerber, M; Du Plessis, J

    2016-04-01

    A novel HPLC method with UV detection for the identification and quantification of roxithromycin (ROX) during in vitro skin penetration studies has been developed and validated. The method proved to be simple and rapid with isocratic elution (flow rate: 1.0 mL/min) of ROX, using a C18 column and UV detection at 205 nm. The mobile phase consisted of 0.06 M potassium di-hydrogen orthophosphate buffer (pH adjusted to 7.4 with sodium hydroxide) and acetonitrile in a 50:50 (v/v) ratio. This method showed linearity across the concentration range of 5 - 1000 μg/mL with a correlation coefficient of 0.9999. An average recovery of 101.78% was obtained. Limit of detection (LOD) and lower limit of quantification (LLOQ) values proved that ROX can still be detected at a concentration level of 0.3 μg/mL and accurately quantified at a concentration of 0.5 μg/mL. The specificity testing during method validation proved that this method is suitable for the accurate detection and quantification of ROX even when combined with different compounds typically used during the formulation of topical delivery systems. PMID:27209694

  14. RP-HPLC Determination of Phenylalkanoids and Monoterpenoids in Rhodiola rosea and Identification by LC-ESI-TOF

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An HPLC method permitting the simultaneous determination of fourteen compounds (phenylalkanoids and monoterpenoids) from the roots of Rhodiola rosea was developed. A separation was achieved within 35 minutes by using C-18 column material, a water/acetonitrile mobile phase, both containing 0.05% phos...

  15. Characterization of zebrafish cardiac proteome using online pH gradient SCX-RP HPLC-MS/MS platform.

    PubMed

    Zhang, Jiang; Lanham, Kevin A; Heideman, Warren; Peterson, Richard E; Li, Lingjun

    2013-01-01

    Two-dimensional HPLC coupled with tandem MS (MS/MS) has become a mainstream technique in the shotgun proteomics for large-scale identification of proteins from biological samples. This powerful technology provides speed, sensitivity, and dynamic range which are essential to probe complex peptide mixtures from proteomic samples. Herein we present a pH gradient SCX-RP 2D HPLC-MS/MS method designed to improve the peptide resolution and protein identification from complex proteomic samples. The comparison between the pH gradient SCX-RP 2D HPLC method and traditional salt gradient SCX-RP method was presented. A two-step sample prefractionation method utilizing microwave-assisted tryptic digestion to improve the identification of insoluble proteins was also introduced. This novel 2D HPLC-MS/MS method was applied to the heart proteomic sample of the zebrafish, Danio rerio, to provide comprehensive cardiac proteomic profiling of this important model organism for cardiovascular and environmental toxicology studies. PMID:23606253

  16. Isolation and characterization of degradation products of citalopram and process-related impurities using RP-HPLC.

    PubMed

    Rao, Ramisetti Nageswara; Raju, Ale Narasa; Narsimha, Ramaram

    2008-06-01

    A reversed-phase high-performance liquid chromatographic method for simultaneous separation and determination of citalopram hydrobromide and its process impurities in bulk drugs and pharmaceutical formulations was developed. The separation was accomplished on an Inertsil ODS 3V (250x4.6 mm; particle size 5 mum) column using 0.3% diethylamine (pH = 4.70) and methanol/acetonitrile (55:45 v/v) as mobile phase in a gradient elution mode. The eluents were monitored by a photodiode array detector set at 225 nm. The chromatographic behavior of all the related substances was examined under variable conditions of different solvents, buffer concentrations, and pH. The method was validated in terms of accuracy, precision, and linearity. The method could be of use not only for rapid and routine evaluation of the quality of citalopram in bulk drug manufacturing units but also for the detection of its impurities in pharmaceutical formulations. Three unknown impurities were consistently observed during the analysis of different batches of citalopram. Forced degradation of citalopram was carried out under thermal, photo, acidic, alkaline, and peroxide conditions. The degradation products and unknown impurities were isolated and characterized by ESI-MS/MS, (1)H NMR, and FT-IR spectroscopy. PMID:18481321

  17. Simultaneous Determination of Six Active Compounds in Yixin Badiranjibuya Granules, a Traditional Chinese Medicine, by RP-HPLC-UV Method

    PubMed Central

    Yu, Ning; He, ChenHui; Awuti, Gulistan; Zeng, Cheng; Xing, JianGuo; Huang, Wei

    2015-01-01

    In this study, a sensitive, precise, and accurate HPLC-UV method was developed and validated to simultaneously determine the six analytes (luteolin-7-O-β-D-glucuronide, apigenin-7-O-β-D-glucuronide, diosmetin-7-O-β-D-glucuronide, acacetin-7-O-β-D-glucuronide, tilianin, and rosmarinic acid) in Yixin Badiranjibuya Granules, in which five analytes (i.e., luteolin-7-O-β-D-glucuronide, apigenin-7-O-β-D-glucuronide, diosmetin-7-O-β-D-glucuronide, acacetin-7-O-β-D-glucuronide, and rosmarinic acid) were determined for the first time in Yixin Badiranjibuya Granules, the content of tilianin in Yixin Badiranjibuya Granules was reported in other literatures, and the content of tilianin in our work was higher than that of the literature reports. The quality of 11 batch samples from four different manufacturers was evaluated using the proposed determination method. The contents of the six analytes were largely different among samples from various manufacturers. Therefore, this determination method can provide a scientific basis for quality evaluation and control of Yixin Badiranjibuya Granules. PMID:26587308

  18. Validation of RP-HPLC Method for Simultaneous Quantification of Bicalutamide and Hesperetin in Polycaprolactone-Bicalutamide-Hesperetin-Chitosan Nanoparticles.

    PubMed

    Arya, Abhishek; Khandelwal, Kiran; Singh, Aanchal; Ahmad, Hafsa; Agrawal, Satish; Khatik, Renuka; Mittapelly, Naresh; Dwivedi, Anil Kumar

    2015-10-01

    Bicalutamide is a non-steroidal anti-androgen drug used for the treatment of androgen-dependent prostate cancer. Hesperetin is a natural bioflavonoid that can be used in combination with bicalutamide to improve efficacy and decrease tolerance. The aim of the present work was to develop and validate a simple, sensitive, rapid reverse phase-high performance liquid chromatographic method for simultaneous estimation of bicalutamide and hesperetin. The validation parameters such as specificity, linearity, precision and accuracy, limit of detection (LOD) and limit of quantification (LOQ) were determined according to International Conference on Harmonization ICH Q2 (R1) guidelines. Chromatographic separation was achieved on Lichrocart(®) CN column (250 × 4 mm, 5 µm, MERCK) with isocratic elution. The retention times and detection wavelength, for hesperetin and bicalutamide were 4.28 min, 288 nm and 5.90 min, 270 nm respectively. The intra-day and inter-day assay precision and accuracy were found to be <2% over linearity of 50-2000 ng/mL with R(2) 0.999. LOD and LOQ, of bicalutamide and hesperetin was 14.70, 44.57 ng/mL and 16.11, 48.84 ng/mL, respectively. The method was successfully applied for encapsulation efficiency and drug release studies from bicalutamide and hesperetin loaded nanoparticles. PMID:26045585

  19. A Validated RP-HPLC Method for the Analysis of 1-Fluoronaphthalene and Its Process-Related Impurities.

    PubMed

    Karagiannidou, Evrykleia G; Bekiari, Eleni T; Vastardi, Elli I

    2015-09-01

    A simple and precise reversed-phase high-performance liquid chromatography method was developed and validated for the determination of 1-fluoronaphthalene and its process-related impurities, 1-aminonaphthalene, 1-nitronaphthalene, naphthalene and 2-fluoronaphthalene. 1-Fluoronaphthalene is the key starting material for the synthesis of duloxetine hydrochloride active pharmaceutical ingredient and is therefore a potential impurity of the API. The determination of the impurity profile is critical for the safety assessment of a substance and manufacturing process thereof. In duloxetine hydrochloride active pharmaceutical ingredient, only 1-fluoronaphthalene is detected and neither of its related impurities of 1-aminonaphthalene, 1-nitronaphthalene, naphthalene and 2-fluoronaphthalene. Chromatography was carried out on a Symmetry C18 (250 × 4.6 mm, 5 μm) column, using mobile phase A-a mixture of 0.01 Μ KH2PO4 buffer (pH 2.5 ± 0.1):methanol:acetonitrile in the ratio of 35:52:13 v/v/v and mobile phase B-a mixture of methanol:acetonitrile in the ratio of 80:20 v/v at a flow rate of 1.0 mL/min. The analytes were monitored using photo diode array detector at 230 nm. The proposed method is found to be having linearity in the concentration of 0.075-5.000 μg/mL, 0.150-5.000 μg/mL, 0.3125-5.000 μg/mL and 0.3125-5.000 μg/mL for 1-aminonaphthalene, 1-nitronaphthalene, naphthalene and 2-fluoronaphthalene, respectively, with correlation coefficients of 0.9998, 0.9998, 0.9997 and 0.9997, respectively. The proposed method was validated as per the International Conference on Harmonization guidelines. The mean recoveries for all the studied impurities are in the range of 90-110%. Due to its specificity, high precision and accuracy, the developed method can be used for the determination of 1-fluoronaphthalene, key starting material for the synthesis of duloxetine hydrochloride API. PMID:25713107

  20. Quality by Design Approach for Simultaneous Estimation of Doxycycline Hyclate and Curcumin by RP-HPLC Method.

    PubMed

    Dhal, C; Ahmad, F J; Chauhan, A; Jyothi, M; Singh, R M; Saini, P K; Mathur, S C; Singh, G N

    2015-01-01

    A simple, rapid, reliable, robust and optimized reversed phase high performance liquid chromatographic method for simultaneous estimation of doxycycline hyclate and curcumin was successfully developed and validated as per International Conference on Harmonization guidelines. The objective was achieved in terms of well separated peaks within 10 min on a Waters Sunfire C8 column with dimensions of 250×4.6 mm, particle size 5.0 μm using mobile phase consisting of 30 volumes of potassium dihydrogen phosphate buffer (50 mM) adjusted to pH 6.5±0.1 with triethylamine and 70 volumes of methanol at flow rate of 0.85 ml/min. The column effluents were monitored at 400 nm maintained at ambient column temperature (28(o)). The developed method was found linear over the concentration range of 200-700 μg/ml for doxycycline hyclate and 8-28 μg/ml for curcumin, the detection and quantitation limit was found to be 26.063 and 78.97 μg/ml for doxycycline hyclate; 0.795 and 2.13 μg/ml for curcumin, respectively. The developed method was optimized using Minitab software version 16 to meet the current quality by design requirements. The method validation was done for linearity, range, detection and quantitation limit, accuracy, precision, specificity, system suitability testing, and robustness. PMID:26997700

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  2. Stability-indicating reversed-phase HPLC method development and characterization of impurities in vortioxetine utilizing LC-MS, IR and NMR.

    PubMed

    Liu, Lei; Cao, Na; Ma, Xingling; Xiong, Kaihe; Sun, Lili; Zou, Qiaogen; Yao, Lili

    2016-01-01

    The current study reports the development and validation of a stability-indicating reversed phase HPLC method for the separation and identification of potential impurities in vortioxetine, a recently developed antidepressant. The structures of a new compound and four process-related impurities formed during the synthesis were characterized and confirmed by NMR, MS, and IR spectroscopy analyses. The most probable formation mechanisms of the impurities identified were proposed. Based on the characterization data, the new compound was proposed to be 1-[4-[(2,4-dimethylphenyl)thio]phenyl]-piperazine. In addition, an efficient chromatographic method was optimized to separate and quantify the impurities, which were obtained in the 0.05-0.75 μg/mL range. The developed HPLC method was validated with respect to accuracy, precision, linearity, robustness, and limits of detection and quantitation. PMID:26412721

  3. Optimization of a reversed-phase high-performance liquid chromatography/mass spectrometry method for characterizing recombinant antibody heterogeneity and stability.

    PubMed

    Dillon, Thomas M; Bondarenko, Pavel V; Rehder, Douglas S; Pipes, Gary D; Kleemann, Gerd R; Ricci, Margaret Speed

    2006-07-01

    An enhanced analytical RP-HPLC/MS method was developed for monitoring the stability and production of intact and fragmented monoclonal antibodies (MAbs). The use of high column temperatures (70-80 degrees C), organic solvents with high eluotropic strength coefficients (isopropyl and n-propyl alcohols), and Zorbax StableBond columns, were critical for good recovery and resolution of immunoglobulin G1 (IgG1) and IgG2 monoclonal antibodies. Using this method, cleavage products of a degraded IgG1 antibody were clearly separated and identified by in-line electrospray ionization time-of-flight (ESI-TOF) mass spectrometry generating exact masses and unique terminal ladder sequences. The glycosylation profile, including mapping of the terminal galactose and fucose heterogeneity of the N-linked sugars, was determined by mass spectrometry of intact MAbs. In addition, we discovered that several IgG2 MAbs exhibited greater structural heterogeneity compared to IgG1s. Mass spectral characterization data and reduction data suggested that the heterogeneity is disulfide related. This reversed-phase LC/MS method represents a key advancement in monitoring intact MAb production and stability. PMID:16448656

  4. A New Rapid and Sensitive Stability-Indicating UPLC Assay Method for Tolterodine Tartrate: Application in Pharmaceuticals, Human Plasma and Urine Samples

    PubMed Central

    Yanamandra, Ramesh; Vadla, Chandra Sekhar; Puppala, Umamaheshwar; Patro, Balaram; Murthy, Yellajyosula. L. N.; Ramaiah, Parimi Atchuta

    2012-01-01

    A new rapid, simple, sensitive, selective and accurate reversed-phase stability-indicating Ultra Performance Liquid Chromatography (RP-UPLC) technique was developed for the assay of Tolterodine Tartrate in pharmaceutical dosage form, human plasma and urine samples. The developed UPLC method is superior in technology to conventional HPLC with respect to speed, solvent consumption, resolution and cost of analysis. Chromatographic run time was 6 min in reversed-phase mode and ultraviolet detection was carried out at 220 nm for quantification. Efficient separation was achieved for all the degradants of Tolterodine Tartrate on BEH C18 sub-2-μm Acquity UPLC column using Trifluoroacetic acid and acetonitrile as organic solvent in a linear gradient program. The active pharmaceutical ingredient was extracted from tablet dosage form using a mixture of acetonitrile and water as diluent. The calibration graphs were linear and the method showed excellent recoveries for bulk and tablet dosage form. The test solution was found to be stable for 40 days when stored in the refrigerator between 2 and 8 °C. The developed UPLC method was validated and meets the requirements delineated by the International Conference on Harmonization (ICH) guidelines with respect to linearity, accuracy, precision, specificity and robustness. The intra-day and inter-day variation was found be less than 1%. The method was reproducible and selective for the estimation of Tolterodine Tartrate. Because the method could effectively separate the drug from its degradation products, it can be employed as a stability-indicating one. PMID:22396907

  5. Development and validation of a stability-indicating reverse phase ultra performance liquid chromatographic method for the estimation of nebivolol impurities in active pharmaceutical ingredients and pharmaceutical formulation.

    PubMed

    Thummala, Veera Raghava Raju; Lanka, Mohana Krishna

    2015-10-01

    A sensitive, stability-indicating gradient reverse phase ultra performance liquid chromatographic method has been developed for the quantitative estimation of nebivolol impurities in active pharmaceutical ingredient (API) and pharmaceutical formulation. Efficient chromatographic separation was achieved on an Acquity BEH C18 column (100 mm x 2.1 mm, 1.7 μm) with mobile phase of a gradient mixture. The flow rate of the mobile phase was 0.18 mL/min with column temperature of 30 degrees C and detection wavelength of 281 nm. The relative response factor values of (R*)-2-( benzylamino)-1-((S*)-6-fluorochroman-2-yl) ethanol ((R x S*) NBV-), (R)-1-((R)-6-fluorochroman-2-yl)-2-((S)-2-((S)-6-fluoro-chroman-2-yl)-2-hydroxyethyl-amino) ethanol ((RRSS) NBV-3), 1-(chroman-2-yl)-2-(2-(6-fluorochroman-2-yl)-2-hydroxyethyl amino) ethanol (monodesfluoro impurity), (S)-1-((R)-6-fluorochroman-2-yl)-2-((R)-2 (S*)-6-fluoro-chroman-2-yl)-2-hydroxyethylamino) ethanol hydrochloride ((RSRS) NBV-3) and (R*)-1-((S*)-6-fluorochroman-2-yl)-2-((S*)-2-((S*)-6-fluoro-chroman-2-yl)-2-hydroxyethylamino) ethanol ((R* S* S* S*) NBV-2) were 0.65, 0.91, 0.68, 0.92 and 0.91 respectively. Nebivolol formulation sample was subjected to the stress conditions of acid, base, oxidative, hydrolytic, thermal, humidity and photolytic degradation. Nebivolol was found to degrade significantly under peroxide stress condition. The degradation products were well resolved from nebivolol and its impurities. The peak purity test results confirmed that the nebivolol 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 International Conference on Hormonization (ICH) guidelines with respect to specificity, linearity, limits of detection and quantification, accuracy, precision and robustness. PMID:26930962

  6. Development and validation of a stability indicating method for S-carboxymethyl-L-cysteine and related degradation products in oral syrup formulation.

    PubMed

    Fanigliulo, Ameriga; De Filippis, Piero; Curcuruto, Ornella; Repeto, Paolo; Roveda, Davide; Hartenstein, Matthew; Adams, Erwin; Cabooter, Deirdre

    2015-11-10

    A stability-indicating method for the determination of S-carboxymethyl-L-cysteine and related degradation impurities in Exputex® 250mg/5mL syrup was developed in anion-exchange liquid chromatography mode. A forced degradation study supported the method development to ensure stability indicating conditions. Aqueous solutions of the active pharmaceutical ingredient and syrup samples at different pH-values were stress-tested in different thermal, light exposure and headspace conditions. One degradation product was detected in thermal stress studies at 60°C and 80°C in the pH range 5.0-7.0 and was identified by mass spectrometry as 5-oxo-thiomorpholine-3-carboxylic acid (lactam of carbocysteine). A second degradation product was only generated in moderately strong oxidizing conditions (0.5% H2O2 aqueous solution) and was identified as S-carboxymethyl-L-cysteine-(R/S)-sulphoxide (carbocysteine sulphoxide). The method was developed on a Zorbax SAX column, in isocratic mode. The mobile phase consisted of 200mM phosphate solution at pH 4.0 and acetonitrile (50:50 v/v) and UV detection was performed at a wavelength of 205nm. The method was linear for carbocysteine (R>0.9982) over a concentration range of 2.5-50μg/mL and 0.4-0.6mg/mL. Linearity for the impurities was shown from the LOQ to 50μg/mL. Specificity was verified and accuracy demonstrated for the active ingredient and its degradation products in syrup samples at 3 levels around their respective specification limits. Repeatability, intermediate precision and inter-laboratory reproducibility were assessed on three commercial batches, analyzed in triplicate by two operators at both the transferring and the receiving site and demonstrated a successful method transfer to the manufacturing quality control laboratory. PMID:26159351

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

    PubMed Central

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

    2012-01-01

    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 μm 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 μg/mL to 76.194 μg/mL for desloratadine and 1.006 μg/mL to 301.67 μg/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

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

    PubMed

    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

    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 μm) 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 μg 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 μg 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

  9. 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)

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

    2014-09-01

    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 (λmax: 520 nm) or amaranth dye (λmax: 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 μg mL-1 for methods A, B and C, respectively. The limits of detection and quantitation were 0.40, 0.292 and 0.113 μg mL-1 and 0.782, 0.973 and 0.376 μg 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.

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

    PubMed

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

    2014-09-15

    Simple, rapid and accurate high performance liquid chromatographic (HPLC) and spectrophotometric methods are described for determination of antihistaminic acrivastine in capsules. The first method (method A) is based on accurate, sensitive and stability indicating chromatographic separation method. Chromolith® Performance RP-18e column, a relatively new packing material consisting of monolithic rods of highly porous silica, was used as stationary phase applying isocratic binary mobile phase of ACN and 25 mM NaH2PO4 pH 4.0 in the ratio of 22.5:77.5 at flow rate of 5.0 mL/min and 40°C. A diode array detector was used at 254 nm for detection. The elution time of acrivastine was found to be 2.080±0.032. The second and third methods (methods B and C) are based on the oxidation of acrivastine with excess N-bromosuccinimide (NBS) and determination of the unconsumed NBS with, metol-sulphanilic acid (λmax: 520 nm) or amaranth dye (λmax: 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 μg mL(-1) for methods A, B and C, respectively. The limits of detection and quantitation were 0.40, 0.292 and 0.113 μg mL(-1) and 0.782, 0.973 and 0.376 μg mL(-1) for methods A, B and C, respectively. The HPLC method was validated for system suitability, linearity, precision, limits of detection and quantitation, specificity, stability and robustness. Stability tests were done through exposure of the analyte solution for four different stress conditions and the results indicate no interference of degradants with HPLC-method. The proposed methods was favorably applied for determination of acrivastine in capsules formulation. Statistical comparison of the obtained results from the analysis of the studied drug to those of the reported method using t- and F-tests showed no significant difference between them. PMID:24813276

  11. Least-Squares Regression and Spectral Residual Augmented Classical Least-Squares Chemometric Models for Stability-Indicating Analysis of Agomelatine and Its Degradation Products: A Comparative Study.

    PubMed

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

    2016-01-01

    Two accurate, sensitive, and selective stability-indicating methods are developed and validated for simultaneous quantitative determination of agomelatine (AGM) and its forced degradation products (Deg I and Deg II), whether in pure forms or in pharmaceutical formulations. Partial least-squares regression (PLSR) and spectral residual augmented classical least-squares (SRACLS) are two chemometric models that are being subjected to a comparative study through handling UV spectral data in range (215-350 nm). For proper analysis, a three-factor, four-level experimental design was established, resulting in a training set consisting of 16 mixtures containing different ratios of interfering species. An independent test set consisting of eight mixtures was used to validate the prediction ability of the suggested models. The results presented indicate the ability of mentioned multivariate calibration models to analyze AGM, Deg I, and Deg II with high selectivity and accuracy. The analysis results of the pharmaceutical formulations were statistically compared to the reference HPLC method, with no significant differences observed regarding accuracy and precision. The SRACLS model gives comparable results to the PLSR model; however, it keeps the qualitative spectral information of the classical least-squares algorithm for analyzed components. PMID:26987554

  12. 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

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

    2014-03-01

    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

  13. A rapid stability-indicating, fused-core HPLC method for simultaneous determination of β-artemether and lumefantrine in anti-malarial fixed dose combination products

    PubMed Central

    2013-01-01

    Background Artemisinin-based fixed dose combination (FDC) products are recommended by World Health Organization (WHO) as a first-line treatment. However, the current artemisinin FDC products, such as β-artemether and lumefantrine, are inherently unstable and require controlled distribution and storage conditions, which are not always available in resource-limited settings. Moreover, quality control is hampered by lack of suitable analytical methods. Thus, there is a need for a rapid and simple, but stability-indicating method for the simultaneous assay of β-artemether and lumefantrine FDC products. Methods Three reversed-phase fused-core HPLC columns (Halo RP-Amide, Halo C18 and Halo Phenyl-hexyl), all thermostated at 30°C, were evaluated. β-artemether and lumefantrine (unstressed and stressed), and reference-related impurities were injected and chromatographic parameters were assessed. Optimal chromatographic parameters were obtained using Halo RP-Amide column and an isocratic mobile phase composed of acetonitrile and 1mM phosphate buffer pH 3.0 (52:48; V/V) at a flow of 1.0 ml/min and 3 μl injection volume. Quantification was performed at 210 nm and 335 nm for β-artemether and for lumefantrine, respectively. In-silico toxicological evaluation of the related impurities was made using Derek Nexus v2.0®. Results Both β-artemether and lumefantrine were separated from each other as well as from the specified and unspecified related impurities including degradants. A complete chromatographic run only took four minutes. Evaluation of the method, including a Plackett-Burman robustness verification within analytical QbD-principles, and real-life samples showed the method is suitable for quantitative assay purposes of both active pharmaceutical ingredients, with a mean recovery relative standard deviation (± RSD) of 99.7 % (± 0.7%) for β-artemether and 99.7 % (± 0.6%) for lumefantrine. All identified β-artemether-related impurities were predicted in Derek

  14. A new, rapid, stability-indicating UPLC method for separation and determination of impurities in amlodipine besylate, valsartan and hydrochlorothiazide in their combined tablet dosage form.

    PubMed

    Vojta, Jiří; Jedlička, Aleš; Coufal, Pavel; Janečková, Lucie

    2015-05-10

    A new rapid stability-indicating UPLC method for separation and determination of impurities in amlodipine besylate, valsartan and hydrochlorothiazide in their combined tablet dosage form was developed. The separation of Ph. Eur. related substances of amlodipine besylate (A, B, D, E, F, G), hydrochlorothiazide (A, B, C), valsartan (B, C), two other valsartan impurities (S)-2-(N-{[2'-cyanobiphenyl-4-yl]methyl}pentanamido)-3-methylbutanoic acid and (S)-3-methyl-2-{[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methylamino}butanoic acid and several unknown impurities was achieved by reversed phase liquid chromatography with UV detection. The detection wavelengths were set as follows: 225nm for valsartan, its impurities and for the impurity D of amlodipine, 271nm for hydrochlorothiazide and its impurities and 360nm for amlodipine and its impurities except for impurity D. Zorbax Eclipse C8 RRHD (100mm×3.0mm, 1.8μm) was used as a separation column and the analytes were eluted within 11min by a programmed gradient mixture of 0.01M phosphate buffer pH 2.5 and acetonitrile. The method was successfully validated in accordance to the International Conference of Harmonization (ICH) guidelines for amlodipine besylate and its impurity D, valsartan and its impurity C and hydrochlorothiazide and its impurities A, B and C. The triple-combined tablets were exposed to thermal, higher humidity, acid, alkaline, oxidative and photolytic stress conditions. Stressed samples were analyzed by the proposed method. All the significant degradation products and impurities were satisfactory separated from each other and from the principal peaks of drug substances. The peak purity test complied for peaks of amlodipine, valsartan and hydrochlorothiazide in all the stressed samples and indicated no co-elution of degradation products. The method was found to be precise, linear, accurate, sensitive, specific, robust and stability-indicating and could be used as a routine purity test method for amlodipine

  15. A bioanalytical HPLC method for coumestrol quantification in skin permeation tests followed by UPLC-QTOF/HDMS stability-indicating method for identification of degradation products.

    PubMed

    Bianchi, Sara E; Teixeira, Helder F; Kaiser, Samuel; Ortega, George G; Schneider, Paulo Henrique; Bassani, Valquiria L

    2016-05-01

    Coumestrol is present in several species of the Fabaceae family widely distributed in plants. The estrogenic and antioxidant activities of this molecule show its potential as skin anti-aging agent. These characteristics reveal the interest in developing analytical methodology for permeation studies, as well as to know the stability of coumestrol identifying the major degradation products. Thus, the present study was designed, first, to develop and validate a versatile liquid chromatography (HPLC) method to quantify coumestrol in a hydrogel formulation in different porcine skin layers (stratum corneum, epidermis, and dermis) in permeation tests. In the stability-indicating test coumestrol samples were exposed to stress conditions: temperature, UVC light, oxidative, acid and alkaline media. The degradation products, as well as the constituents extracted from the hydrogel, adhesive tape or skin were not eluted in the retention time of the coumestrol. Hence, the HPLC method showed to be versatile, specific, accurate, precise and robust showing excellent performance for quantifying coumestrol in complex matrices involving skin permeation studies. Coumestrol recovery from porcine ear skin was found to be in the range of 97.07-107.28μg/mL; the intra-day precision (repeatability) and intermediate precision (inter-day precision), respectively lower than 4.71% and 2.09%. The analysis using ultra-performance liquid chromatography coupled to a quadrupole time-of-flight high definition mass spectrometry detector (UPLC-QTOF/HDMS) suggest the MS fragmentation patterns and the chemical structure of the main degradation products. These results represent new and relevant findings for the development of coumestrol pharmaceutical and cosmetic products. PMID:27010353

  16. Stability-indicating RP-LC method for determination of azilsartan medoxomil and chlorthalidone in pharmaceutical dosage forms: application to degradation kinetics.

    PubMed

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

    2014-10-01

    A RP-LC method was developed and validated for simultaneous determination of the active components, azilsartan medoxomil (AZL) and chlorthalidone (CLT), in their novel antihypertensive combined recipe. The chromatographic separation was achieved on an Eclipse XDB-C18 (4.6 × 150 mm, 5 μm) column using a mobile phase consisting of methanol/potassium hydrogen phosphate buffer (pH 8, 0.05 M) (40:60, v/v) in isocratic mode. The flow rate was maintained at 0.8 mL min(-1) at ambient temperature. Detection was carried out at 210 nm. The method was validated according to the ICH guidelines. Linearity, accuracy, and precision were satisfactory over the concentration range of 5.0-50.0 and 2.5-25.0 μg mL(-1) for AZL and CLT, respectively (r (2) = 0.9999). LODs for AZL and CLT were 0.90 and 0.32 μg mL(-1), whereas LOQs were 2.72 and 0.98 μg mL(-1), respectively. Both drugs were subjected to forced degradation studies under hydrolysis (neutral, acidic, and alkaline), oxidative, and photolytic extensive stress conditions. The proposed method is stability indicating by the resolution of the investigated drugs from their degradation products. Moreover, the kinetics of the acidic degradation of AZL as well as the kinetics of the alkaline degradation of CLT were investigated. Arrhenius plots were constructed and the apparent first-order rate constants, half-life times, shelf-life times, and the activation energies of the degradation processes were calculated. The method was successfully applied for the determination of the studied drugs simultaneously in their coformulated tablet. The developed method is specific and stability indicating for the quality control and routine analysis of the cited medications in their pharmaceutical preparations. PMID:25190009

  17. Using an innovative Quality-by-Design approach for development of a stability indicating UHPLC method for ebastine in the API and pharmaceutical formulations.

    PubMed

    Schmidt, Alexander H; Molnár, Imre

    2013-05-01

    A stability-indicating ultra high performance liquid chromatographic (UHPLC) method has been developed for purity testing of ebastine and its pharmaceutical formulations. Successful chromatographic separation of the API from impurities was achieved on a Waters Acquity UPLC BEH C18, 50 mm × 2.1 mm, 1.7 μm particle size column with gradient elution of 10 mM acetate buffer pH 6.2 and a mixture of acetonitrile/2-propanol (1:1) as the mobile phase. Incorporating Quality by Design (QbD) principles to the method development approach by using the chromatography modeling software DryLab4 allows the visualization of a "Design Space", a region in which changes to method parameters will not significantly affect the results as defined in the ICH guideline Q8 (R2). A verification study demonstrated that the established model for Design Space is accurate with a relative error of prediction of only 0.6%. The method was fully validated for specificity, linearity, accuracy and precision, and robustness in compliance to the ICH guideline Q2 (R1). The method was found to be linear in the concentration range from the quantification limit (LOQ) to 125% of the specification limit for ebastine and each of the impurities with correlation coefficients of not less than 0.999. The recovery rate was between 98.15 and 100.30% for each impurity. The repeatability and intermediate precision (RSD) were less than 3.2% for ebastine and each of the impurities. The robustness of the developed method was studied by varying the six parameters: gradient time, temperature, ternary composition of the eluent, flow rate and start and end concentration of the gradient at 3 levels (+1, 0, -1). The resulting 729 experiments were performed in silico from the previously constructed model for Design Space and showed that the required resolution of 2.0 can be reached in all experiments. To prove the stability-indicating performance of the method, forced degradation (acid and base hydrolysis, oxidation, photolytic

  18. Pathogens and fecal indicators in waste stabilization pond systems with direct reuse for irrigation: Fate and transport in water, soil and crops.

    PubMed

    Verbyla, M E; Iriarte, M M; Mercado Guzmán, A; Coronado, O; Almanza, M; Mihelcic, J R

    2016-05-01

    Wastewater use for irrigation is expanding globally, and information about the fate and transport of pathogens in wastewater systems is needed to complete microbial risk assessments and develop policies to protect public health. The lack of maintenance for wastewater treatment facilities in low-income areas and developing countries results in sludge accumulation and compromised performance over time, creating uncertainty about the contamination of soil and crops. The fate and transport of pathogens and fecal indicators was evaluated in waste stabilization ponds with direct reuse for irrigation, using two systems in Bolivia as case studies. Results were compared with models from the literature that have been recommended for design. The removal of Escherichia coli in both systems was adequately predicted by a previously-published dispersed flow model, despite more than 10years of sludge accumulation. However, a design equation for helminth egg removal overestimated the observed removal, suggesting that this equation may not be appropriate for systems with accumulated sludge. To assess the contamination of soil and crops, ratios were calculated of the pathogen and fecal indicator concentrations in soil or on crops to their respective concentrations in irrigation water (termed soil-water and crop-water ratios). Ratios were similar within each group of microorganisms but differed between microorganism groups, and were generally below 0.1mLg(-1) for coliphage, between 1 and 100mLg(-1) for Giardia and Cryptosporidium, and between 100 and 1000mLg(-1) for helminth eggs. This information can be used for microbial risk assessments to develop safe water reuse policies in support of the United Nations' 2030 Sustainable Development Agenda. PMID:26881733

  19. Development and validation of a stability-indicating RP-UPLC method for the quantitative analysis of nabumetone in tablet dosage form.

    PubMed

    Sethi, Neha; Anand, Ankit; Chandrul, Kaushal K; Jain, Garima; Srinivas, Kona S

    2012-02-01

    High efficiency and less run time are the basic requirements of high-speed chromatographic separations. To fulfill these requirements, a new separation technique, ultra-performance liquid chromatography (UPLC), has shown promising developments. A rapid, specific, sensitive, and precise reverse-phase UPLC method is developed for the determination of nabumetone in tablet dosage form. In this work, a new isocratic chromatographic method is developed. The newly developed method is applicable for assay determination of the active pharmaceutical ingredient. The chromatographic separation is achieved on a Waters Acquity BEH column (100 mm, i.d., 2.1 mm, 1.7 µm) within a short runtime of 2 min using a mobile phase of 5 mM ammonium acetate-acetonitrile (25:75, v/v), at a flow rate of 0.3 mL/min at an ambient temperature. Quantification is achieved with photodiode array detection at 230 nm, over the concentration range of 0.05-26 µg/mL. Forced degradation studies are also performed for nabumetone bulk drug samples to demonstrate the stability-indicating power of the UPLC method. Comparison of system performance with conventional high-performance liquid chromatography is made with respect to analysis time, efficiency, and sensitivity. The method is validated according to the ICH guidelines and is applied successfully for the determination of nabumetone in tablets. PMID:22298755

  20. Development and validation of stability-indicating high performance liquid chromatography method to analyze gatifloxacin in bulk drug and pharmaceutical preparations

    PubMed Central

    Aljuffali, Ibrahim A.; Kalam, Mohd. Abul; Sultana, Yasmin; Imran, Ahamad; Alshamsan, Aws

    2014-01-01

    Quantitative determination of gatifloxacin in tablets, solid lipid nanoparticles (SLNs) and eye-drops using a very simple and rapid chromatographic technique was validated and developed. Formulations were analyzed using a reverse phase SUPELCO® 516 C-18-DB, 50306-U, HPLC column (250 mm × 4.6 mm, 5 μm) and a mobile phase consisting of disodium hydrogen phosphate buffer:acetonitrile (75:25, v/v) and with orthophosphoric acid pH was adjusted to 3.3 The flow rate was 1.0 mL/min and analyte concentrations were measured using a UV-detector at 293 nm. The analyses were performed at room temperature (25 ± 2 °C). Gatifloxacin was separated in all the formulations within 2.767 min. There were linear calibration curves over a concentration range of 4.0–40 μg.mL−1 and correlation coefficients of 0.9998 with an average recovery above 99.91%. Detection of analyte from different dosage forms at the same Rt indicates the specificity and stability of the developed method. PMID:25685047

  1. QbD-Based Development and Validation of a Stability-Indicating HPLC Method for Estimating Ketoprofen in Bulk Drug and Proniosomal Vesicular System.

    PubMed

    Yadav, Nand K; Raghuvanshi, Ashish; Sharma, Gajanand; Beg, Sarwar; Katare, Om P; Nanda, Sanju

    2016-03-01

    The current studies entail systematic quality by design (QbD)-based development of simple, precise, cost-effective and stability-indicating high-performance liquid chromatography method for estimation of ketoprofen. Analytical target profile was defined and critical analytical attributes (CAAs) were selected. Chromatographic separation was accomplished with an isocratic, reversed-phase chromatography using C-18 column, pH 6.8, phosphate buffer-methanol (50 : 50v/v) as a mobile phase at a flow rate of 1.0 mL/min and UV detection at 258 nm. Systematic optimization of chromatographic method was performed using central composite design by evaluating theoretical plates and peak tailing as the CAAs. The method was validated as per International Conference on Harmonization guidelines with parameters such as high sensitivity, specificity of the method with linearity ranging between 0.05 and 250 µg/mL, detection limit of 0.025 µg/mL and quantification limit of 0.05 µg/mL. Precision was demonstrated using relative standard deviation of 1.21%. Stress degradation studies performed using acid, base, peroxide, thermal and photolytic methods helped in identifying the degradation products in the proniosome delivery systems. The results successfully demonstrated the utility of QbD for optimizing the chromatographic conditions for developing highly sensitive liquid chromatographic method for ketoprofen. PMID:26514627

  2. Stability-Indicating Liquid Chromatographic Method for the Quantification of the New Antipsychotic Agent Asenapine in Bulk and in Pharmaceutical Formulation

    PubMed Central

    Chhalotiya, Usmangani K.; Bhatt, Kashyap K.; Shah, Dimal A.; Patel, Jigar R.

    2012-01-01

    A simple, specific and stability-indicating reversed phase high performance liquid chromatographic method was developed for the quantitative determination of asenapine in tablet dosage form. A SunFire C18, 5 μm column having 250×4.6 mm i.d. in isocratic mode, with mobile phase containing 0.02 M potassium dihydrogen phosphate: acetonitrile (95:05, v/v, pH 3.5 adjusted with 1% o-phosphoric acid) was used. The flow rate was 1.0 mL min−1 and effluents were monitored at 232 nm. The retention time of asenapine was 5.51 min. The linearity for asenapine was in the range of 0.1–20 μg/ml. The recoveries obtained for asenapine were 98.31–101.51%. Asenapine stock solutions were subjected to acid and alkali hydrolysis, chemical oxidation, sunlight and dry heat degradation. The degraded product peaks were well resolved from the pure drug peak with significant difference in their retention time values. Stressed samples were assayed using developed LC method. The proposed method was validated with respect to linearity, accuracy, precision and robustness. The method was successfully applied to the estimation of asenapine in tablet dosage form. PMID:22896826

  3. Development and validation of stability-indicating high performance liquid chromatography method to analyze gatifloxacin in bulk drug and pharmaceutical preparations.

    PubMed

    Aljuffali, Ibrahim A; Kalam, Mohd Abul; Sultana, Yasmin; Imran, Ahamad; Alshamsan, Aws

    2015-01-01

    Quantitative determination of gatifloxacin in tablets, solid lipid nanoparticles (SLNs) and eye-drops using a very simple and rapid chromatographic technique was validated and developed. Formulations were analyzed using a reverse phase SUPELCO® 516 C-18-DB, 50306-U, HPLC column (250 mm × 4.6 mm, 5 μm) and a mobile phase consisting of disodium hydrogen phosphate buffer:acetonitrile (75:25, v/v) and with orthophosphoric acid pH was adjusted to 3.3 The flow rate was 1.0 mL/min and analyte concentrations were measured using a UV-detector at 293 nm. The analyses were performed at room temperature (25 ± 2 °C). Gatifloxacin was separated in all the formulations within 2.767 min. There were linear calibration curves over a concentration range of 4.0-40 μg.mL(-1) and correlation coefficients of 0.9998 with an average recovery above 99.91%. Detection of analyte from different dosage forms at the same Rt indicates the specificity and stability of the developed method. PMID:25685047

  4. Removal of Fecal Indicators, Pathogenic Bacteria, Adenovirus, Cryptosporidium and Giardia (oo)cysts in Waste Stabilization Ponds in Northern and Eastern Australia

    PubMed Central

    Sheludchenko, Maxim; Padovan, Anna; Katouli, Mohammad; Stratton, Helen

    2016-01-01

    Maturation ponds are used in rural and regional areas in Australia to remove the microbial loads of sewage wastewater, however, they have not been studied intensively until present. Using a combination of culture-based methods and quantitative real-time PCR, we assessed microbial removal rates in maturation ponds at four waste stabilization ponds (WSP) with (n = 1) and without (n = 3) baffles in rural and remote communities in Australia. Concentrations of total coliforms, E. coli, enterococci, Campylobacter spp., Salmonella spp., F+ RNA coliphage, adenovirus, Cryptosporidium spp. and Giardia (oo) cysts in maturation ponds were measured at the inlet and outlet. Only the baffled pond demonstrated a significant removal of most of the pathogens tested and therefore was subjected to further study by analyzing E. coli and enterococci concentrations at six points along the baffles over five sampling rounds. Using culture-based methods, we found a decrease in the number of E. coli and enterococci from the initial values of 100,000 CFU per 100 mL in the inlet samples to approximately 1000 CFU per 100 mL in the outlet samples for both bacterial groups. Giardia cysts removal was relatively higher than fecal indicators reduction possibly due to sedimentation. PMID:26729150

  5. Development and Validation of Stability-Indicating HPTLC Method for Estimation of Naratriptan Hydrochloride in Its Pharmaceutical Dosage Form and Its Content Uniformity Testing.

    PubMed

    Prajapati, Pintu B; Chotalia, Jagdish; Bodiwala, Kunjan B; Marolia, Bhavin P; Shah, Shailesh A

    2016-08-01

    The present research project involves development and validation of a stability-indicating HPTLC method for the estimation of naratriptan-HCl in their pharmaceutical dosage forms and its content uniformity testing. Naratriptan-HCl was subjected to alkaline, acidic, oxidative, neutral, thermal (dry heat) and photo-degradation conditions. The chromatographic separation was carried out using a precoated silica gel G 60 F254 TLC plate as the stationary phase and dichloromethane-toluene-methanol-triethylamine (4 : 4 : 2 : 1, v/v/v/v) as the mobile phase. The spots of NRT-HCl and its degradation products were detected at 290 nm. The Rf value of NRT-HCl was found to be 0.60 ± 0.02. The linearity was obtained in the range of 100-500 ng/spot. The limit of detection and limit of quantitation were found to be 6.07 ng/spot and 18.41 ng/spot, respectively. The percentage recovery was found in the range of 98.87-99.55%. NRT-HCl was degraded under acidic, alkaline and oxidative conditions while stable under photolytic, neutral and dry heat conditions. The developed method was applied for estimation of naratriptan-HCl in marketed formulations and its content uniformity testing. PMID:27406125

  6. Stress degradation studies and development of stability-indicating TLC-densitometry method for determination of prednisolone acetate and chloramphenicol in their individual and combined pharmaceutical formulations.

    PubMed

    Musharraf, Syed Ghulam; Fatima, Urooj; Sultana, Rahat

    2012-01-01

    A rapid and reproducible stability indicating TLC method was developed for the determination of prednisolone acetate and chloramphenicol in presence of their degraded products. Uniform degradation conditions were maintained by refluxing sixteen reaction mixtures for two hours at 80°C using parallel synthesizer including acidic, alkaline and neutral hydrolysis, oxidation and wet heating degradation. Oxidation at room temperature, photochemical and dry heating degradation studies were also carried out. Separation was done on TLC glass plates, pre-coated with silica gel 60F-254 using chloroform: methanol (14:1 v/v). Spots at Rf 0.21 ± 0.02 and Rf 0.41 ± 0.03 were recognized as chloramphenicol and prednisolone acetate, respectively. Quantitative analysis was done through densitometric measurements at multiwavelength (243 nm, λmax of prednisolone acetate and 278 nm, λmax of chloramphenicol), simultaneously. The developed method was optimized and validated as per ICH guidelines. Method was found linear over the concentration range of 200-6000 ng/spot with the correlation coefficient (r2 ± S.D.) of 0.9976 ± 3.5 and 0.9920 ± 2.5 for prednisolone acetate and chloramphenicol, respectively. The developed TLC method can be applied for routine analysis of prednisolone acetate and chloramphenicol in presence of their degraded products in their individual and combined pharmaceutical formulations. PMID:22264235

  7. Stress degradation studies and development of stability-indicating TLC-densitometry method for determination of prednisolone acetate and chloramphenicol in their individual and combined pharmaceutical formulations

    PubMed Central

    2012-01-01

    A rapid and reproducible stability indicating TLC method was developed for the determination of prednisolone acetate and chloramphenicol in presence of their degraded products. Uniform degradation conditions were maintained by refluxing sixteen reaction mixtures for two hours at 80°C using parallel synthesizer including acidic, alkaline and neutral hydrolysis, oxidation and wet heating degradation. Oxidation at room temperature, photochemical and dry heating degradation studies were also carried out. Separation was done on TLC glass plates, pre-coated with silica gel 60F-254 using chloroform: methanol (14:1 v/v). Spots at Rf 0.21 ± 0.02 and Rf 0.41 ± 0.03 were recognized as chloramphenicol and prednisolone acetate, respectively. Quantitative analysis was done through densitometric measurements at multiwavelength (243 nm, λmax of prednisolone acetate and 278 nm, λmax of chloramphenicol), simultaneously. The developed method was optimized and validated as per ICH guidelines. Method was found linear over the concentration range of 200-6000 ng/spot with the correlation coefficient (r2 ± S.D.) of 0.9976 ± 3.5 and 0.9920 ± 2.5 for prednisolone acetate and chloramphenicol, respectively. The developed TLC method can be applied for routine analysis of prednisolone acetate and chloramphenicol in presence of their degraded products in their individual and combined pharmaceutical formulations. PMID:22264235

  8. A validated stability-indicating ultra performance liquid chromatography method for the determination of potential process-related impurities in eplerenone.

    PubMed

    Du, Mingluo; Pan, Chunyan; Chen, Jing; Song, Min; Zhu, Tingting; Hang, Taijun

    2016-08-01

    A simple, sensitive, and accurate stability-indicating analytical method has been developed and validated using ultra high performance liquid chromatography. The developed method is used to evaluate the related substances of eplerenone (EP). The degradation behavior of EP under stress conditions was determined, and the major degradants were identified by ultra high performance liquid chromatography with tandem mass spectrometry. The chromatographic conditions were optimized using an impurity-spiked solution, and the samples, generated from forced degradation studies. The resolution of EP, its potential impurities, and its degradation products was performed on a Waters UPLC BEH C18 column (50 × 2.1 mm, 1.7 μm) by linear gradient elution using a mobile phase consisting of 10 mmol/L ammonium acetate adjusted to pH 4.5, methanol and acetonitrile. A photo-diode array detector set at 245 nm was used for detection. The flow rate was set at 0.3 mL/min. The procedure had good specificity, linearity (0.02-3.14 μg/mL), recovery (96.1-103.9%), limit of detection (0.01-0.02 μg/mL), limit of quantitation (0.03-0.05 μg/mL), and robustness. The correction factors of the process-related substances were calculated. PMID:27256957

  9. Validated stability-indicating liquid chromatographic method for the determination of ribavirin in the presence of its degradation products: application to degradation kinetics.

    PubMed

    Belal, Fathalla; Sharaf El-Din, Mohie K; Eid, Manal I; El-Gamal, Rania M

    2015-04-01

    Ribavirin was found to be liable to acidic, alkaline, oxidative and photolytic degradation. Hence, a simple, sensitive and stability-indicating reversed-phase liquid chromatographic method was developed and validated for the determination of ribavirin in the presence of its degradation products. The analysis was carried out on an ODS C18 (250 × 4.6 mm i.d.) stainless steel column using a mobile phase consisting of 0.02 M potassium dihydrogen phosphate. The analysis was performed at ambient temperature with a flow rate of 1 mL/min and UV detection at 207 nm. Pyridoxine hydrochloride was used as an internal standard. The method showed good linearity over the concentration range of 2.0-40 µg/mL with limit of detection of 0.34 µg/mL and limit of quantification of 1.03 µg/mL. The suggested method was successfully applied for the analysis of ribavirin in its commercial capsules. Statistical evaluation and comparison of the data obtained by the proposed and comparison method revealed good accuracy and precision of the proposed method. The drug was exposed to forced alkaline, acidic, oxidative and photolytic degradation according to the ICH guidelines. Moreover, the method was utilized to investigate the kinetics of alkaline and acidic degradation of the drug. The apparent first-order rate constants, half-life times and activation energies of the degradation process were calculated. PMID:25092904

  10. Removal of Fecal Indicators, Pathogenic Bacteria, Adenovirus, Cryptosporidium and Giardia (oo)cysts in Waste Stabilization Ponds in Northern and Eastern Australia.

    PubMed

    Sheludchenko, Maxim; Padovan, Anna; Katouli, Mohammad; Stratton, Helen

    2016-01-01

    Maturation ponds are used in rural and regional areas in Australia to remove the microbial loads of sewage wastewater, however, they have not been studied intensively until present. Using a combination of culture-based methods and quantitative real-time PCR, we assessed microbial removal rates in maturation ponds at four waste stabilization ponds (WSP) with (n = 1) and without (n = 3) baffles in rural and remote communities in Australia. Concentrations of total coliforms, E. coli, enterococci, Campylobacter spp., Salmonella spp., F+ RNA coliphage, adenovirus, Cryptosporidium spp. and Giardia (oo) cysts in maturation ponds were measured at the inlet and outlet. Only the baffled pond demonstrated a significant removal of most of the pathogens tested and therefore was subjected to further study by analyzing E. coli and enterococci concentrations at six points along the baffles over five sampling rounds. Using culture-based methods, we found a decrease in the number of E. coli and enterococci from the initial values of 100,000 CFU per 100 mL in the inlet samples to approximately 1000 CFU per 100 mL in the outlet samples for both bacterial groups. Giardia cysts removal was relatively higher than fecal indicators reduction possibly due to sedimentation. PMID:26729150

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

    PubMed

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

    2013-01-01

    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, 150Χ4.6 mm, 5 μ 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

  12. Implementation of design of experiments for optimization of forced degradation conditions and development of a stability-indicating method for furosemide.

    PubMed

    Kurmi, Moolchand; Kumar, Sanjay; Singh, Bhupinder; Singh, Saranjit

    2014-08-01

    The study involved optimization of forced degradation conditions and development of a stability-indicating method (SIM) for furosemide employing the design of experiment (DoE) concept. The optimization of forced degradation conditions, especially hydrolytic and oxidative, was done by application of 2(n) full factorial designs, which helped to obtain the targeted 20-30% drug degradation and also enriched levels of degradation products (DPs). For the selective separation of the drug and its DPs for the development of SIM, DoE was applied in three different stages, i.e., primary parameter selection, secondary parameter screening and method optimization. For these three, IV-optimal, Taguchi orthogonal array and face-centred central composite designs were employed, respectively. The organic modifier, buffer pH, gradient time and initial hold time were selected as primary parameters. Initial and final organic modifier percentage, and flow rate came out as critical parameters during secondary parameter screening, which were further evaluated during method optimization. Based on DoE results, an optimized method was obtained wherein a total of twelve DPs were separated successfully. The study also exposed the degradation behaviour of the drug in different forced degradation conditions. PMID:24742772

  13. Stability-indicating determination of trimetazidine dihydrochloride inthe presence of two of its related substances using a direct GC/MS method.

    PubMed

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

    2014-01-01

    A novel, simple, direct, and selective stability- indicating GC/MS procedure was developed for the determination of the anti-ischemic drug trimetazidine dihydrochloride (TMZ) in the presence of two of its related substances (potential impurities), namely, 2,3,4-trimethoxybenzyl alcohol (T1) and 2,3,4-trimethoxybenzaldehyde (T2). The method involved resolution of the undeilvatized compounds using a 100% dimethylpolysiloxane (Rtx-1) capillary column, and MS detection was carried out in the electron-impact mode. The peaks of the three compounds eluted at retention times 11.69, 11.92, and 15.47 min for T1, T2, and TMZ, respectively. Quantification of the parent drug TMZ was based on measuring its peak area. The reliability and analytical performance of the proposed method, including linearity, range, precision, accuracy, selectivity, detection, and quantification limits, were statistically validated. The calibration curve of TMZ was linear over the range 100-600 μg/mL. The proposed method was successfully applied to the assay of TMZ in several commercially available pharmaceutical formulations with recoveries not lessthan 96.2%. PMID:25632428

  14. Stability-indicating LC assay for butenafine hydrochloride in creams using an experimental design for robustness evaluation and photodegradation kinetics study.

    PubMed

    Barth, Aline Bergesch; de Oliveira, Gabriela Bolfe; Malesuik, Marcelo Donadel; Paim, Clésio Soldatelli; Volpato, Nadia Maria

    2011-08-01

    A stability-indicating liquid chromatography method for the determination of the antifungal agent butenafine hydrochloride (BTF) in a cream was developed and validated using the Plackett-Burman experimental design for robustness evaluation. Also, the drug photodegradation kinetics was determined. The analytical column was operated with acetonitrile, methanol and a solution of triethylamine 0.3% adjusted to pH 4.0 (6:3:1) at a flow rate of 1 mL/min and detection at 283 nm. BTF extraction from the cream was done with n-butyl alcohol and methanol in ultrasonic bath. The performed degradation conditions were: acid and basic media with HCl 1M and NaOH 1M, respectively, oxidation with H(2)O(2) 10%, and the exposure to UV-C light. No interference in the BTF elution was verified. Linearity was assessed (r(2) = 0.9999) and ANOVA showed non-significative linearity deviation (p > 0.05). Adequate results were obtained for repeatability, intra-day precision, and accuracy. Critical factors were selected to examine the method robustness with the two-level Plackett-Burman experimental design and no significant factors were detected (p > 0.05). The BTF photodegradation kinetics was determined for the standard and for the cream, both in methanolic solution, under UV light at 254 nm. The degradation process can be described by first-order kinetics in both cases. PMID:21801482

  15. Improved efficiency and stability of secnidazole – An ideal delivery system

    PubMed Central

    Khan, Salman; Haseeb, Mohd; Baig, Mohd Hassan; Bagga, Paramdeep Singh; Siddiqui, H.H.; Kamal, M.A.; Khan, Mohd Sajid

    2014-01-01

    Secnidazole (α,2-Dimethyl-5-nitro-1H-imidazole-1-ethanol) is a highly effective drug against a variety of G+/G− bacteria but with significant side effects because it is being used in very high concentration. In this study, gold nanoparticles (GNPS) were selected as a vehicle to deliver secnidazole drug at the specific site with more accuracy which made the drug highly effective at substantially low concentrations. The as-synthesized GNPs were capped with Human Serum Albumin (HSA) and subsequently bioconjugated with secnidazole because HSA provides the stability and improves the solubility of the bioconjugated drug, secnidazole. The quantification of covalently bioconjugated secnidazole with HSA encapsulated on enzymatically synthesized GNPs was done with RP-HPLC having SPD-20 A UV/VIS detector by using the C-18 column. The bioconjugation of GNPs with secnidazole was confirmed by Transmission Electron Microscopy (TEM) and Dynamic Light Scattering (DLS). The bioconjugated GNPs were characterized by UV–VIS spectroscopy, TEM, Scanning Electron Microscopy (SEM) and DLS. Zeta potential confirmed the stability and uniform distribution of particles in the emulsion of GNPs. The separation of bioconjugated GNPs, unused GNPs and unused drug was done by gel filtration chromatography. The minimal inhibitory concentration of secnidazole-conjugated gold nanoparticles (Au-HSA-Snd) against Klebsiella pneumonia (NCIM No. 2957) and Bacillus cereus (NCIM No. 2156) got improved by 12.2 times and 14.11 times, respectively, in comparison to pure secnidazole. Precisely, the MIC of Au-HSA-Snd against K. pneumonia (NCIM No. 2957) and B. cereus (NCIM No. 2156) were found to be 0.35 and 0.43 μg/ml, respectively whereas MIC of the pure secnidazole drug against the same bacteria were found to be 4.3 and 6.07 μg/ml, respectively. PMID:25561882

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

    PubMed

    Vidović, Stojanka; Stojanović, Biljana; Veljković, Jelena; Prazić-Arsić, Ljiljana; Roglić, Goran; Manojlović, Dragan

    2008-08-22

    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

  17. A selective and sensitive stability-indicating HPLC method for the validated assay of etoposide from commercial dosage form and polymeric tubular nanocarriers.

    PubMed

    Algan, Aslihan Hilal; Gumustas, Mehmet; Karatas, Aysegul; Ozkan, Sibel A

    2016-05-30

    Etoposide is a topoisomerase II enzyme inhibitor type chemotherapeutic agent which is widely used in the therapy of various cancers. Its short half-life and toxicity to normal tissues are the major drawbacks in its clinical applications. Polymeric nanoparticulate drug delivery systems are rational carriers to deliver etoposide with higher efficiency and fewer side effects. In addition tubular shaped drug carriers are found to show a great potential for drug delivery on the basis of promising results regarding particle shape and cellular uptake. In this study, etoposide loaded polymeric tubular nanocarriers have been developed by template wetting method using porous anodic aluminum oxide membranes as templates. The developed poly(methyl methacrylate) nanocarriers were evaluated for structural analysis, in vitro drug release studies and drug release kinetics. Accurate and reliable determination of the drug release from newly developed nanocarriers, is of great importance. For this reason a selective and sensitive reversed phase liquid chromatography method was developed and fully validated from the point of system suitability, specificity, linearity and range, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy and robustness for the reliable determination of etoposide. Stability indicating capability was shown with forced degradation studies and the chromatographic conditions were optimized on ACE 5C18 (150 mm × 4.6mm I.D., 5 μm) analytical column. Related to the calibration results ETP was found linear in the range between 0.2 from 100 μg mL(-1) with the LOD as 0.015 μg.mL(-1). The resultant conditions were applied for the selective and sensitive determination of etoposide from its commercial dosage form with the high accuracy values (99.82-100.65%). The method was successfully detected assay of etoposide release from newly developed polymeric tubular nanocarriers, which was found as 72.2% at the end of 24h. PMID:26971031

  18. Application of a Stability-Indicating HPTLC Method for Simultaneous Quantitative Determination of Olmesartan Medoxomil and Hydrochlorothiazide in Pharmaceutical Dosage Forms.

    PubMed

    Ilango, Kaliappan; Shiji Kumar, Pushpangadhan S

    2013-01-01

    A rapid, precise, sensitive, economical, and validated high performance thin layer chromatographic method is developed for simultaneous quantification of olmesartan medoxomil and hydrochlorothiazide in combined tablet dosage form. The method used amlodipine as internal standard (IS). Chromatographic separations were achieved on silica gel 60 F254 plates using toluene-methanol-ethyl acetate-acetone (2.5 : 1 : 0.5 : 2, v/v/v/v) as mobile phase. Densitometric analysis was carried out in the reflectance mode at 258 nm. Calibration curves were linear over a range of 80-480 ng/band for olmesartan medoxomil and 25-150 ng/band for hydrochlorothiazide. The detection and quantification limits were found to be 18.12 and 56.35 ng/band for olmesartan medoxomil and 6.31 and 18.56 ng/band for hydrochlorothiazide, respectively. Intra- and interassay precision provided relative standard deviations lower than 2% for both analytes. Recovery from 99.60 to 101.22% for olmesartan medoxomil and 98.30 to 99.32% for hydrochlorothiazide show good accuracy. Both the drugs were also subjected to acid, alkali, oxidation, heat, and photodegradation studies. The degradation products obtained were well resolved from pure drugs with significantly different R f values. As the method could effectively separate the drugs from their degradation products, it can be used for stability-indicating analysis. Validation of the method was carried out as per international conference on harmonization (ICH) guidelines. PMID:24319604

  19. Validated Stability-Indicating HPLC-DAD Method for the Simultaneous Determination of Diclofenac Sodium and Diflunisal in Their Combined Dosage Form

    PubMed Central

    Shaalan, Rasha A.; Belal, Tarek S.

    2013-01-01

    A simple, rapid, and highly selective HPLC-DAD method was developed for the simultaneous determination of diclofenac sodium (DIC) and diflunisal (DIF) in pure form and in their combined formulation. Effective chromatographic separation was achieved using a Zorbax SB-C8 (4.6×250 mm, 5 μm particle size) column with a mobile phase composed of 0.05 M phosphoric acid, acetonitrile, and methanol in the ratio of 40:48:12 (by volume). The mobile phase was pumped isocratically at a flow rate of 1 mL/min, and quantification of the analytes was based on measuring their peak areas at 228 nm. The retention times for diflunisal and diclofenac were about 7.9 and 9.5 min, respectively. The reliability and analytical performance of the proposed HPLC procedure were statistically validated with respect to system suitability, linearity, ranges, precision, accuracy, specificity, robustness, detection, and quantification limits. Calibration curves were linear in the ranges of 5–100 μg/mL for both drugs with correlation coefficients >0.9998. The proposed method proved to be selective and stability-indicating by the resolution of the two analytes from four of their related substances and potential impurities as well as from forced-degradation (hydrolysis, oxidation, photolysis, and dry heat) products. The validated HPLC method was successfully applied to the analysis of DIC and DIF in their combined dosage form (suppositories). The proposed method made use of the diode array detector (DAD) as a tool for peak identity and purity confirmation. PMID:24106669

  20. LC and LC-MS study of stress decomposition behaviour of isoniazid and establishment of validated stability-indicating assay method.

    PubMed

    Bhutani, Hemant; Singh, Saranjit; Vir, Sanjay; Bhutani, K K; Kumar, Raj; Chakraborti, Asit K; Jindal, K C

    2007-03-12

    Isoniazid was subjected to different ICH prescribed stress conditions of thermal stress, hydrolysis, oxidation and photolysis. The drug was stable to dry heat (50 and 60 degrees C). It showed extensive decomposition under hydrolytic conditions, while it was only moderately sensitive to oxidation stress. The solid drug turned intense yellow on exposure to light under accelerated conditions of temperature (40 degrees C) and humidity (75% RH). In total, three major degradation products were detected by LC. For establishment of stability-indicating assay, the reaction solutions in which different degradation products were formed were mixed, and the separation was optimized by varying the LC conditions. An acceptable separation was achieved using a C-18 column and a mobile phase comprising of water:acetonitrile (96:4, v/v), with flow rate and detection wavelength being 0.5 ml min(-1) and 254 nm, respectively. The degradation products appeared at relative retention times (RR(T)) of 0.71, 1.34 and 4.22. The validation studies established a linear response of the drug at concentrations between 50 and 1000 microg ml(-1). The mean values (+/-R.S.D.) of slope, intercept and correlation coefficient were 35,199 (+/-0.88), 114,310 (+/-4.70) and 0.9998 (+/-0.01), respectively. The mean R.S.D. values for intra- and inter-day precision were 0.24 and 0.90, respectively. The recovery of the drug ranged between 99.42 and 100.58%, when it was spiked to a mixture of solutions in which sufficient degradation was observed. The specificity was established through peak purity testing using a photodiode array detector. The method worked well on application to marketed formulation of isoniazid, and a fixed-dose combination containing isoniazid and ethambutol HCl. It was even extendable to LC-MS studies, which were carried out to identify the three degradation products. The m/z values of the peaks at RR(T) 0.71 and RR(T) 1.34 matched with isonicotinic acid and isonicotinamide, respectively

  1. Setup and validation of a convenient sampling procedure to promptly and effectively stabilize vitamin C in blood and plasma specimens stored at routine temperatures.

    PubMed

    Rossi, Barbara; Tittone, Francesca; Palleschi, Simonetta

    2016-07-01

    Vitamin C (ascorbic acid, AA) is very labile in nature and decays quickly after blood withdrawal. To ensure AA stability, the current procedure prescribes immediate plasma acidification followed by sample storage at ultra-low temperature. The aim of this study was to set up a pre-analytical procedure to promptly stabilize AA at routine temperatures while minimizing both specimen manipulation and instrumental requirement. Blood from healthy subjects was collected in lithium-heparin gel separator tubes containing or not different reducing agents (dithioerythritol, tris(2-carboxyethyl)phosphine, n-acetylcysteine and sodium thiosulfate). Plasma AA stability during blood and plasma storage at routine temperatures was evaluated. Plasma AA concentration was assayed by RP-HPLC-UV under ion suppression conditions. Each of the reductants tested was able to slow down the ex vivo degradation of plasma AA; dithioerythritol was the most effective. Five to 10 mmol/L dithioerythritol did not interfere with blood separation and allowed plasma AA to be stabilized up to 6 h, 24 h and 60 days at room temperature, +4 °C and -25 °C, respectively. The method worked well even in case of delayed blood separation and/or incomplete vacutainer filling. The procedure is feasible and reliable. Of special usefulness in clinical and epidemiological studies, prompt plasma manipulation after blood withdrawal or special storage equipments are not required. Graphical Abstract Collecting blood in tubes containing a reducing agent is a feasible method to promptly and effectively stabilize plasma vitamin C at routine temperature. PMID:27113458

  2. Longitudinal Stability of Social Competence Indicators in a Portuguese Sample: Q-Sort Profiles of Social Competence, Measures of Social Engagement, and Peer Sociometric Acceptance

    ERIC Educational Resources Information Center

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

    2014-01-01

    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…

  3. Stability-indicating HPLC method development and structural elucidation of novel degradation products in posaconazole injection by LC-TOF/MS, LC-MS/MS and NMR.

    PubMed

    Yang, Yidi; Zhu, Xi; Zhang, Fei; Li, Wei; Wu, Ying; Ding, Li

    2016-06-01

    Stress testing was carried out under acidic, alkaline, oxidative, thermal and photolytic conditions to evaluate the intrinsic stability of posaconazole injection. A total of four degradation products were detected and the drug was found to be susceptible to oxidative and thermal degradations. Three unknown degradants formed under oxidative stress condition were isolated by preparative HPLC and unambiguously elucidated by LC-TOF/MS, LC-MS/MS, (1)H NMR, (13)C NMR and 2D NMR techniques. Based on the spectrometric and spectroscopic information, these novel degradation products were unequivocally assigned as the N-oxides of posaconazole. Probable mechanisms for the formation of the degradants were proposed. A new and selective HPLC method was developed and validated to separate, detect and quantify all the degradants in posaconazole injection. PMID:27023129

  4. Determination of Cefixime by a Validated Stability-Indicating HPLC Method and Identification of its Related Substances by LC-MS/MS Studies

    PubMed Central

    Talebpour, Zahra; Pourabdollahi, Hakimeh; Rafati, Hasan; Abdollahpour, Asem; Bashour, Yusef; Aboul-Enein, Hassan Y.

    2013-01-01

    Cefixime is an important cephalosporin antibiotic that easily decomposes and releases different related substances in preparation and storage steps. The objective of the current study was to develop a simple, precise, and accurate isocratic liquid chromatography (LC) method for the determination of cefixime in the presence of its related substances generated from thermal stress in the bulk drug. The chromatographic conditions were comprised of a reversed-phase C18 column (4.6 × 250 mm, 5 μm) with a mobile phase composed of water: acetonitrile (85:15 v/v, with 0.5% formic acid) and ultraviolet detection (UV). Some thermal degradation products were identified using a proposed liquid chromatography-mass spectrometry method. Five peaks (A, B, C, D, and E impurities based on British Pharmacopoeia) were known and a few unknown peaks appeared in the thermal stress solution of cefixime. The linear regression analysis data for the calibration plot of the LC-UV method showed a good linear relationship in the concentration range 0.9–1000.0 μg mL−1. The recovery of the optimized method was between 94.6 and 98.4% and the inter- and intra-day relative standard deviations were less than 3.3%. The obtained results shown in the LC-UV proposed method can be conveniently used in a quality control laboratory for routine analysis of cefixime for the assay and related substances, as well as for the evaluation of stability samples of bulk drugs. PMID:23833715

  5. Development and validation of a selective, sensitive and stability indicating UPLC-MS/MS method for rapid, simultaneous determination of six process related impurities in darunavir drug substance.

    PubMed

    A, Vijaya Bhaskar Reddy; Yusop, Zulkifli; Jaafar, Jafariah; Aris, Azmi B; Majid, Zaiton A; Umar, Khalid; Talib, Juhaizah

    2016-09-01

    In this study a sensitive and selective gradient reverse phase UPLC-MS/MS method was developed for the simultaneous determination of six process related impurities viz., Imp-I, Imp-II, Imp-III, Imp-IV, Imp-V and Imp-VI in darunavir. The chromatographic separation was performed on Acquity UPLC BEH C18 (50 mm×2.1mm, 1.7μm) column using gradient elution of acetonitrile-methanol (80:20, v/v) and 5.0mM ammonium acetate containing 0.01% formic acid at a flow rate of 0.4mL/min. Both negative and positive electrospray ionization (ESI) modes were operated simultaneously using multiple reaction monitoring (MRM) for the quantification of all six impurities in darunavir. The developed method was fully validated following ICH guidelines with respect to specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), accuracy, precision, robustness and sample solution stability. The method was able to quantitate Imp-I, Imp-IV, Imp-V at 0.3ppm and Imp-II, Imp-III, and Imp-VI at 0.2ppm with respect to 5.0mg/mL of darunavir. The calibration curves showed good linearity over the concentration range of LOQ to 250% for all six impurities. The correlation coefficient obtained was >0.9989 in all the cases. The accuracy of the method lies between 89.90% and 104.60% for all six impurities. Finally, the method has been successfully applied for three formulation batches of darunavir to determine the above mentioned impurities, however no impurity was found beyond the LOQ. This method is a good quality control tool for the trace level quantification of six process related impurities in darunavir during its synthesis. PMID:27262107

  6. Development and Validation of Stability-Indicating Method for Estimation of Chlorthalidone in Bulk and Tablets with the Use of Experimental Design in Forced Degradation Experiments

    PubMed Central

    Sonawane, Sandeep; Jadhav, Sneha; Rahade, Priya; Chhajed, Santosh; Kshirsagar, Sanjay

    2016-01-01

    Chlorthalidone was subjected to various forced degradation conditions. Substantial degradation of chlorthalidone was obtained in acid, alkali, and oxidative conditions. Further full factorial experimental design was applied for acid and alkali forced degradation conditions, in which strength of acid/alkali, temperature, and time of heating were considered as independent variables (factors) and % degradation was considered as dependent variable (response). Factors responsible for acid and alkali degradation were statistically evaluated using Yates analysis and Pareto chart. Furthermore, using surface response curve, optimized 10% degradation was obtained. All chromatographic separation was carried out on Phenomenex HyperClone C 18 column (250 × 4.6 mm, 5 μ), using mobile phase comprising methanol : acetonitrile : phosphate buffer (20 mM) (pH 3.0 adjusted with o-phosphoric acid): 30 : 10 : 60% v/v. The flow rate was kept constant at 1 mL/min and eluent was detected at 241 nm. In calibration curve experiments, linearity was found to be in the range of 2–12 μg/mL. Validation experiments proved good accuracy and precision of the method. Also there was no interference of excipients and degradation products at the retention time of chlorthalidone, indicating specificity of the method. PMID:27123364

  7. Planktonic Foram Sr/Ca Indicates Long-Term Stability of Carbonate Saturation State and Seawater Sr/Ca during the Cenozoic

    NASA Astrophysics Data System (ADS)

    Caves, J. K.; Opdyke, B.; Owens, R.

    2012-12-01

    Changes in ocean chemistry are poorly understood over timescales of tens of millions of years; yet, such changes reflect the interplay of fundamental Earth processes, such as the long-term carbon-cycle, evolution, tectonics, and weathering. Simultaneously constraining two ocean chemical parameters could help deconvolve these processes and improve our understanding of the marine response to anthropogenic perturbations to the carbon cycle. We use a multi-proxy and modeling approach, utilizing planktonic foram Sr/Ca, calcite cements, and box-modeling to produce a first-attempt at a Cenozoic carbonate saturation state (Ω) curve and to improve estimates of long-term seawater Sr/Ca variability. Evidence from both culturing studies and glacial-interglacial records indicate that foram Sr/Ca is dominantly sensitive to Ω, suggesting that foram Sr/Ca can be used to reconstruct Ω if seawater Sr/Ca can be constrained. We apply this new proxy to an updated Cenozoic planktonic foram Sr/Ca record, comprising 1680 records from 18 publications. Our foram Sr/Ca record is largely constant during the Cenozoic, with a minimum at the Miocene-Pliocene boundary and a pronounced shift at 38Mya, corresponding to a major planktonic foram overturning event, which we interpret as a species offset. To constrain seawater Sr/Ca, we use both trace element data from calcite cements and a box-model linked to the 87Sr/86Sr record. Both the model and calcite cement data suggest seawater Sr/Ca has remained relatively stable, with slightly higher values during the Paleogene, a minimum during the mid-Miocene, and variability driven by changes in carbonate deposition and mineralogy. Relative to calcite, Ω was low (~4) during much of the Paleogene, but increased during the Oligocene, reaching a maximum during the mid-Miocene. Ω declined to a local minimum at the Miocene-Pliocene boundary, and has since increased to pre-industrial values of 5-6. This record helps explain the lag between the aragonite

  8. Degradation kinetics study of cabozantinib by a novel stability-indicating LC method and identification of its major degradation products by LC/TOF-MS and LC-MS/MS.

    PubMed

    Wu, Chunyong; Xu, Xue; Feng, Chao; Shi, Yuanyuan; Liu, Wenyuan; Zhu, Xiaoyun; Zhang, Junying

    2014-09-01

    The chemical stability of cabozantinib (CBZ) was investigated using a novel stability-indicating LC method. Forced degradation of CBZ was carried out under acidic, basic, thermal, oxidative and photolytic stress conditions. Hydrolysis and oxidation were the primary pathways for this compound and three major unknown degradation products were characterized by LC/TOF-MS and LC-MS/MS. The major oxidative degradation product was isolated by preparative LC and identified by UV, HRMS and NMR techniques to be N-{4-[(N-oxide-6,7-dimethoxyquinolin-4-yl)oxy]phenyl}-N'-(4-fluorophenyl)-cyclopropane-1,1-dicarboxamide. The developed method was validated as per ICH guidelines and then successfully applied to investigate the degradation kinetics of CBZ. Degradation of CBZ followed first-order kinetics under all experimental conditions. A V-shaped pH-rate profile over the pH range 2-10 was observed with maximum stability at pH 6. The effect of temperature on the rate of CBZ degradation was characterized using the Arrhenius equation. The activation energy for hydrolysis was 57.31kJmol(-1) in alkaline solution. PMID:24992215

  9. A validated stability-indicating RP-LC method for the simultaneous determination of amlodipine and perindopril in tablet dosage form and their stress degradation behavior under ICH-recommended stress conditions.

    PubMed

    Gumustas, Mehmet; Ozkan, Sibel A

    2013-01-01

    A stability-indicating RP-LC assay method was developed for the simultaneous determination of the cardiovascular drugs amlodipine and perindopril in the presence of degradation products generated from forced decomposition studies. The developed method is applicable for the determination of related substances in bulk drugs and simultaneous assay in a tablet pharmaceutical dosage form. Separation of the drugs and their degradation products was obtained using an RP Waters Spherisorb ODS1 column (250 x 4.6 mm id, 5 pm particle size) with the mobile phase acetonitrile-water (30 + 70, v/v) containing 15 mM phosphoric acid. The pH of the mobile phase was adjusted to 5.0. A flow rate of 1.2 mL/min was used for the separations, with detection at 215 nm. The chromatographic separation was performed at a column temperature of 45 degrees C. Atenolol was chosen as the internal standard. Amlodipine and perindopril were exposed to thermal, photolytic, hydrolytic, and oxidative stress conditions, and the stressed samples were analyzed by the proposed method. Degradation studies showed that both compounds were degraded under these stress conditions. The method was found to be stability-indicating and can be used for the routine analysis of amlodipine and perindopril in the studied combined tablet dosage form. PMID:24000747

  10. Internet Addiction: Stability and Change

    ERIC Educational Resources Information Center

    Huang, Chiungjung

    2010-01-01

    This longitudinal study examined five indices of stability and change in Internet addiction: structural stability, mean-level stability, differential stability, individual-level stability, and ipsative stability. The study sample was 351 undergraduate students from end of freshman year to end of junior year. Convergent findings revealed stability…

  11. Development of RP UPLC-TOF/MS, stability indicating method for omeprazole and its related substances by applying two level factorial design; and identification and synthesis of non-pharmacopoeial impurities.

    PubMed

    Jadhav, Sushant Bhimrao; Kumar, C Kiran; Bandichhor, Rakeshwar; Bhosale, P N

    2016-01-25

    A new UPLC-TOF/MS compatible, reverse phase-stability indicating method was developed for determination of Omeprazole (OMP) and its related substances in pharmaceutical dosage forms by implementing Design of Experiment (DoE) i.e. two level full factorial Design (2(3)+3 center points=11 experiments) to understand the Critical Method Parameters (CMP) and its relation with Critical Method Attribute (CMA); to ensure robustness of the method. The separation of eleven specified impurities including conversion product of OMP related compound F (13) and G (14) i.e. Impurity-I (1), OMP related compound-I (11) and OMP 4-chloro analog (12) was achieved in a single method on Acquity BEH shield RP18 100 × 2.1 mm, 1.7 μm column, with inlet filter (0.2 μm) using gradient elution and detector wavelength at 305 nm and validated in accordance with ICH guidelines and found to be accurate, precise, reproducible, robust and specific. The drug was found to degrade extensively in heat, humidity and acidic conditions and forms unknown degradation products during stability studies. The same method was used for LC-MS analysis to identify m/z and fragmentation of maximum unknown impurities (Non-Pharmacopoeial) i.e. Impurity-I (1), Impurity-III (3), Impurity-V (5) and Impurity-VIII (9) formed during stability studies. Based on the results, degradation pathway for the drug has been proposed and synthesis of identified impurities i.e. impurities (Impurity-I (1), Impurity-III (3), Impurity-V (5) and Impurity-VIII (9)) are discussed in detail to ensure in-depth understanding of OMP and its related impurities and optimum performance during lifetime of the product. PMID:26600119

  12. RBC indices

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/003648.htm RBC indices To use the sharing features on this page, please enable JavaScript. Red blood cell (RBC) indices are part of the complete blood count ( ...

  13. Development and Validation of a Rapid RP-HPLC-DAD Analysis Method for the Simultaneous Quantitation of Paclitaxel and Lapatinib in a Polymeric Micelle Formulation

    PubMed Central

    Saadat, Ebrahim; Ravar, Fatemeh; Dehghankelishadi, Pouya; Dorkoosh, Farid A.

    2016-01-01

    A robust and rapid analysis method was developed and validated for the simultaneous assay of paclitaxel (PTX) and lapatinib (LPT) in a polymeric micelle formulation as a novel drug delivery system using high-performance liquid chromatography (HPLC). The assay was performed using the C18 MZ-Analytical Column (5 μm, 150 × 4.6 mm, OSD-3) which was protected with the C18 pre-column (5 μm, 4.0 × 4.6 mm, OSD-3). The mobile phase was composed of acetonitrile and water (70/30; V/V) with a flow rate of 0.5 mL/min and detection wavelength of 227 nm. Accuracy was reported as the relative error and was found to be less than 6.8%. The interday assay was evaluated to be 3.22% and 5.76% RSD for PTX and LPT, respectively. The intraday precision was found to be at its maximum value of 5.83% RSD. The limit of detection for both PTX and LPT was found to be 1 µg/mL by means of the newly developed method. The limit of quantitation for PTX and LPT was found to be 5 µg/mL. The calibration curves for both drugs were linear in the concentration range of 5 to 80 μg/mL. In vitro release for both drugs from the polymeric micelle was evaluated using the newly developed analysis method. PMID:27222608

  14. Simultaneous determination of methocarbamol and aspirin by RP-HPLC using fluorescence detection with time programming: its application to pharmaceutical dosage form.

    PubMed

    El-Din, M Sharaf; Eid, M; Zeid, A M

    2013-01-01

    A new simple, rapid and sensitive reversed-phase liquid chromatographic method was developed and validated for the simultaneous determination of methocarbamol (MET) and aspirin (ASP) in their combined dosage form. The separation of these compounds was achieved within 6.0 min on a CLC Shim-pack C8 column (250 × 4.6 mm, 5 µm particle size) using isocratic mobile phase consisting of acetonitrile and 0.02 M dihydrogenphosphate buffer (30:70, v/v) at pH = 5.0. The analysis was performed at a flow rate of 1.0 mL/min with fluorescence detection at 277/313 nm for MET and 298/410 nm for ASP using real-time programming. The selectivity, linearity of calibration, accuracy, inter- and intra-day precision and recovery were examined as parts of the method validation. The concentration-response relationship was linear over concentration ranges of 0.02-0.20 and 0.02-0.40 µg/mL for MET and ASP, respectively, with a limit of detection of 6 and 32 ng/mL for MET and ASP, respectively. The proposed method was successfully applied for the analysis of both MET and ASP in prepared tablets with average recoveries of 99.88 ± 0.65% for MET and 100.44 ± 0.78% for ASP. The results were favourably compared to those obtained by a reference method. PMID:22715138

  15. Development and validation of an RP-HPLC method for the quantitation of odanacatib in rat and human plasma and its application to a pharmacokinetic study.

    PubMed

    Police, Anitha; Gurav, Sandip; Dhiman, Vinay; Zainuddin, Mohd; Bhamidipati, Ravi Kanth; Rajagopal, Sriram; Mullangi, Ramesh

    2015-11-01

    A simple, specific, sensitive and reproducible high-performance liquid chromatography (HPLC) assay method has been developed and validated for the estimation of odanacatib in rat and human plasma. The bioanalytical procedure involves extraction of odanacatib and itraconazole (internal standard, IS) from a 200 μL plasma aliquot with simple liquid-liquid extraction process. Chromatographic separation was achieved on a Symmetry Shield RP18 using an isocratic mobile phase at a flow rate of 0.7 mL/min. The UV detection wave length was 268 nm. Odanacatib and IS eluted at 5.5 and 8.6 min, respectively with a total run time of 10 min. Method validation was performed as per US Food and Drug Administration guidelines and the results met the acceptance criteria. The calibration curve was linear over a concentration range of 50.9-2037 ng/mL (r(2) = 0.994). The intra- and inter-day precisions were in the range of 2.06-5.11 and 5.84-13.1%, respectively, in rat plasma and 2.38-7.90 and 6.39-10.2%, respectively, in human plasma. The validated HPLC method was successfully applied to a pharmacokinetic study in rats. PMID:25914381

  16. Standardization of RP-HPLC methods for the detection of the major peanut allergens Ara h 1, Ara h 2 and Ara h 3.

    PubMed

    Singh, Harmit; Cantoria, Mary Jo; Malave, Poonam; Saputra, Denny; Maleki, Soheila

    2016-03-01

    Crude peanut extract (CPE) was analyzed for three major allergens (Ara h 1, h 2, and h 3) using a C12 and a C18 column at two wavelengths (280 and 220nm) and under different solvent conditions. HPLC profiles were compared for retention time, resolution, and peak heights. CPE samples were spiked with pure allergens to identify the peaks corresponding to allergens. The HPLC fractions of corresponding allergens were collected and freeze-dried in order to perform SDS-PAGE and immunoblotting tests. The best method was identified the one with a shorter retention time, better resolution, and greater peak height as compared with the other methods. In general, the peak heights were greater at 220nm than at 280nm. The major disadvantage of the C12 column was the need for two sets of conditions to identify the allergens as compared to the C18 column where all three allergens could be identified in one run. PMID:26471570

  17. Standardization of RP-HPLC methods for the detection of the major peanut allergens Ara h 1, Ara h 2 and Ara h 3

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Crude peanut extract (CPE) was analyzed for three major allergens (Ara h 1, h 2, and h 3) using a C12 and a C18 column at two wavelengths (280 and 220 nm) and under different solvent conditions. HPLC profiles were compared for retention time, resolution, and peak heights. CPE samples were spiked wit...

  18. Identification and quantification of glutathione and phytochelatins from Chlorella vulgaris by RP-HPLC ESI-MS/MS and oxygen-free extraction.

    PubMed

    Simmons, Denina B D; Hayward, Allison R; Hutchinson, Thomas C; Emery, R J Neil

    2009-10-01

    Phytochelatins are short, cysteine-containing, detoxification peptides produced by plants, algae, and fungi in response to heavy metal exposure. These peptides auto-oxidize easily. Current extraction protocols do not adequately address losses of phytochelatins because of their oxidation and the use of indirect methods for quantification. Method enhancements include the use of an argon environment during extraction to reduce auto-oxidation, the use of glycine-(13)C2-labeled glutathione as an internal standard, and an electrospray ionization source with a triple quadrupole mass spectrometer as a detector. The method-detection limits were 0.081 microM for glutathione, 0.440 microM for phytochelatin 2, and 0.120 microM for phytochelatin 3. These detection limits were comparable to similar studies and were not compromised incorporating these adjustments. The use of a labeled internal standard and an inert gaseous environment during sample preparation greatly improved calibration linearity and sensitivity. Furthermore, phytochelatin degradation was significantly reduced and more accurately tracked. Previous studies involving phytochelatin analyses have likely been subject to higher variability caused by this propensity for phytochelatins to degrade rapidly in air. The method adjustments were simple and cost-effective and allowed phytochelatin analyses to be performed for hours at a time with minimal auto-oxidation. PMID:19688341

  19. Development and validation of RP-HPLC method for the quantitative estimation of αs1-genetic variants in goat milk.

    PubMed

    Montalbano, Maria; Tortorici, Lina; Mastrangelo, Salvatore; Sardina, Maria Teresa; Portolano, Baldassare

    2014-08-01

    A high-performance liquid chromatographic (HPLC) method was developed and validated for separation and quantification of the most common genetic variants of αs1-casein in goat's milk, to evaluate the effect of αs1-casein polymorphisms on casein content. Chromatography was carried out by binary gradient technique on a reversed-phase C8 Zorbax column and the detection was made at a wavelength of 214nm. The procedure was developed using individual raw milk samples of Girgentana goats. For calibration experiments, pure genetic variants were extracted from individual milk samples of animals with known genotypes, considering that commercial standards for goat genetic variants were not available. The data obtained for Girgentana goat breed showed that A, B, F variants were alleles associated with a content of αs1-casein in milk of 3.2±0.4, 5.4±0.5 and 0.7±0.1g/L, respectively, whereas N variant was a 'null' allele associated with the absence of αs1-casein in milk. PMID:24629953

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

    PubMed

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

    2014-01-01

    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

  1. RP-HPLC analysis and in vitro identification of antimycobacterial activity of novel thiosemicarbazides and 1,2,4-triazole derivatives.

    PubMed

    Flieger, Jolanta; Tatarczak-Michalewska, Małgorzata; Wujec, Monika; Pitucha, Monika; Świeboda, Ryszard

    2015-03-25

    It has been widely recognized that chromatography can be applied to derive parameters useful for anticipation of the pharmacological properties of xenobiotics. The purpose of this study was to evaluate the use of C18 stationary phase in chromatographic experiments as to assess antimycobacterial activity of series of novel thiosemicarbazides and their cyclization products: 1,2,4-triazole derivatives. Chromatographically determined lipophilicity descriptors log k(w), S and φ0 and computer generated molecular descriptors were obtained for 32 compounds and Rifampicin as a representative anti-tuberculosis drug. As experimental parameters were not significantly related to the calculated values, the data were analyzed by the principal component analysis PCA allowing for the extraction of "dipole moment" and "energy due to solvation" as the most powerful parameters from large set of diverse data. The approach ranked the examined analytes as active and inactive against Mycobacterium strains. More significant clustering of examined compounds was achieved by construction of 3D graph relating computational (dipole moment, energy due to solvation) and experimental log k(w) (MeOH) descriptors. It was proved that lack of substituent in the C5 position in the triazole ring appears to be characteristic for active derivatives. Provided conclusions can be taken into account in planning further synthesis of new derivatives with antimycobacterial activity. PMID:25700183

  2. Central composite design with the help of multivariate curve resolution in loadability optimization of RP-HPLC to scale-up a binary mixture.

    PubMed

    Taheri, Mohammadreza; Moazeni-Pourasil, Roudabeh Sadat; Sheikh-Olia-Lavasani, Majid; Karami, Ahmad; Ghassempour, Alireza

    2016-03-01

    Chromatographic method development for preparative targets is a time-consuming and subjective process. This can be particularly problematic because of the use of valuable samples for isolation and the large consumption of solvents in preparative scale. These processes could be improved by using statistical computations to save time, solvent and experimental efforts. Thus, contributed by ESI-MS, after applying DryLab software to gain an overview of the most effective parameters in separation of synthesized celecoxib and its co-eluted compounds, design of experiment software that relies on multivariate modeling as a chemometric approach was used to predict the optimized touching-band overloading conditions by objective functions according to the relationship between selectivity and stationary phase properties. The loadability of the method was investigated on the analytical and semi-preparative scales, and the performance of this chemometric approach was approved by peak shapes beside recovery and purity of products. PMID:26768981

  3. Identification of lipopeptide isoforms by MALDI-TOF-MS/MS based on the simultaneous purification of iturin, fengycin, and surfactin by RP-HPLC.

    PubMed

    Yang, Huan; Li, Xu; Li, Xue; Yu, Huimin; Shen, Zhongyao

    2015-03-01

    A three-stage linear gradient strategy using reverse-phase high-performance liquid chromatography (HPLC) was optimized for rapid, high-quality, and simultaneous purification of the lipopeptide isoforms of iturin, fengycin, and surfactin, which may differ in composition by only a single amino acid and/or the fatty acid residue. Matrix-assisted laser desorption ionization time-of-flight tandem mass spectrometry (MALDI-TOF-MS/MS) was applied to detect the lipopeptides harvested from each reversed-phase HPLC peak. Amino acid analysis based on phenyl isothiocyanate derivatization was further used for confirmation of the amino acid species and molar ratio in a certain HPLC fraction. By this MALDI-TOF-MS/MS coupled with amino acid analysis, it was revealed that iturin at m/z 1,043 consists of a circular Asn-Tyr-Asn-Gln-Pro-Asn-Ser peptide and C14 β-OH fatty acid. Surfactin homologs from Bacillus subtilis THY-7 at m/z 1,030, 1,044, 1,058, and 1,072 possess a circular Glu-Leu-Leu-Val-Asp-Leu-Leu peptide and the β-OH fatty acid with a different length (C13-C16). Fengycin species at m/z 1,463 and 1,477 are homologs possessing the circular peptide Glu-Orn-Tyr-Thr-Glu-Ala-Pro-Gln-Tyr-Ile linked to a C16 or C17 γ-OH fatty acid, whereas fengycin at m/z 1,505 contains a Glu-Orn-Tyr-Thr-Glu-Val-Pro-Gln-Tyr-Ile sequence with a Val instead of Ala at position 6. The method developed in this work provided an efficient approach for characterization of diverse lipopeptide isoforms from the iturin, fengycin, and surfactin families. PMID:25662934

  4. Development of a Simple RP-HPLC-UV Method for Determination of Azithromycin in Bulk and Pharmaceutical Dosage forms as an Alternative to the USP Method

    PubMed Central

    Ghari, Tayebeh; Kobarfard, Farzad; Mortazavi, Seyed Alireza

    2013-01-01

    The present study was designed to develop a simple, validated liquid chromatographic method for the analysis of azithromycin in bulk and pharmaceutical dosage forms using ultraviolet detector. The best stationary phase was determined as C18 column, 5 μm, 250 mm × 4.6 mm. Mobile phase was optimized to obtain a fast and selective separation of the drug. Flow rate was 1.5 mL/min, Wavelength was set at 210 nm and the volume of each injection was 500 μL. An isocratic methanol/buffer mobile phase at the ratio of 90:10 v/v gave the best separation and resolution. The proposed method was accurate, precise, sensitive, and linear over a wide range of concentration of azithromycin. The developed method has the advantage of using UV detector compared to the USP method in which electrochemical detector has been used. The validated method was successfully applied to the determination of azithromycin in bulk and pharmaceutical dosage forms. PMID:24250672

  5. Development and validation of RP-HPLC method for simultaneous estimation of nimesulide, phenylephrine hydrochloride, chlorpheniramine maleate and caffeine anhydrous in pharmaceutical dosage form.

    PubMed

    Kumar, Ashok; Sharma, Rishbha; Nair, Anroop; Saini, Gautam

    2012-01-01

    In this study, a simple, specific and accurate reverse phase high performance liquid chromatographic method was developed for the simultaneous determination of nimesulide (NS), phenylephrine hydrochloride (PE), chlorpheniramine maleate (CPM) and caffeine anhydrous (CF) in pharmaceutical dosage forms. A reversed phase Hypersil phenyl column (4.6 mm x 25 cm) with mobile phase having pH 5.5 consisting of methanol and buffer (55:45, v/v) was used. The flow rate was 1.0 mL per minute and the effluents were monitored at 214 nm. The retention times of all the drugs were found to be 7.47 min (NS), 3.944 min (PE), 4.55 min (CF) and 17.15 min (CPM), respectively. The linearity for all the drugs was obtained in the range of 300-800 microg/mL (NS), 15-32 microg/mL (PE), 16-32 microg/mL (CPM) and 30-180 microg/mL (CF), respectively. The results of analysis have been well validated according to guidelines of International Conference of Harmonisation of technical requirements for registration of pharmaceuticals for human use. The method was found to be simple, precise, economical, less time consuming and reproducible. Hence, the suggested procedure could be used for the determination of all the four drugs in commercial preparations. PMID:23285660

  6. Impurity profiling and a stability-indicating UPLC method development and validation for the estimation of related impurities of halobetasol propionate in halobetasol propionate 0.05% (w/w) cream.

    PubMed

    Prakash, Lakkireddy; Malipeddi, H; Subbaiah, B Venkata; Lakka, Narasimha S

    2015-01-01

    A simple, short and stability-indicating reverse phase-ultra-performance liquid chromatography method was developed and validated for the quantitative determination of related impurities of halobetasol propionate in halobetasol propionate 0.05% cream formulation. The proposed method was developed on an ACQUITY UPLC™ BEH Phenyl (2.1 × 100 mm, 1.7 µm) column at 40°C with a mobile phase containing a gradient mixture of potassium hydrogen phosphate buffer and acetonitrile and methanol as modifiers with a runtime of 13.0 min at a monitored wavelength of 242 nm. A simple preparative method and liquid chromatography-mass spectrometry-compatible UPLC method also were developed for the isolation and identification of impurities and degradation products. The drug was subjected to forced-degradation conditions and found to degrade significantly. The stability-indicating capability of the developed method is established by analyzing forced-degradation samples in which the spectral purity of halobetasol propionate is ascertained along with the separation of degradation products from the analyte peak. The developed method was validated as per International Conference on Harmonization guidelines. The developed method is precise (%relative standard deviation <2.0) and is capable of detecting and quantifying all the six impurities at a level of 0.01 and 0.03%, respectively, with respect to test concentration. The wide linearity range, sensitivity, accuracy, short retention time and simple mobile phase imply that the method is suitable for routine quantification of halobetasol propionate and its related substances. PMID:24795078

  7. An eco-friendly stability-indicating spectrofluorimetric method for the determination of two anticancer stereoisomer drugs in their pharmaceutical preparations following micellar enhancement: Application to kinetic degradation studies

    NASA Astrophysics Data System (ADS)

    El-Kimary, Eman I.; El-Yazbi, Amira F.

    2016-06-01

    A new rapid and highly sensitive stability-indicating spectrofluorimetric method was developed for the determination of two stereoisomers anticancer drugs, doxorubicin (DOX) and epirubicin (EPI) in pure form and in pharmaceutical preparations. The fluorescence spectral behavior of DOX and EPI in a sodium dodecyl sulfate (SDS) micellar system was investigated. It was found that the fluorescence intensity of DOX and EPI in an aqueous solution of phosphate buffer pH 4.0 and in the presence of SDS was greatly (about two fold) enhanced and the mechanism of fluorescence enhancement effect of SDS on DOX was also investigated. The fluorescence intensity of DOX or EPI was measured at 553 nm after excitation at 497 nm. The plots of fluorescence intensity versus concentration were rectilinear over a range of 0.03-2 μg/mL for both DOX and EPI with good correlation coefficient (r > 0.999). High sensitivity to DOX and EPI was attained using the proposed method with limits of detection of 10 and 9 ng/mL and limits of quantitation of 29 and 28 ng/mL, for DOX and EPI, respectively. The method was successfully applied for the determination of DOX and EPI in biological fluids and in their commercial pharmaceutical preparations and the results were concordant with those obtained using a previously reported method. The application of the proposed method was extended to stability studies of DOX following different forced degradation conditions (acidic, alkaline, oxidative and photolytic) according to ICH guidelines. Moreover, the kinetics of the alkaline and oxidative degradation of DOX was investigated and the apparent first-order rate constants and half-life times were calculated.

  8. An eco-friendly stability-indicating spectrofluorimetric method for the determination of two anticancer stereoisomer drugs in their pharmaceutical preparations following micellar enhancement: Application to kinetic degradation studies.

    PubMed

    El-Kimary, Eman I; El-Yazbi, Amira F

    2016-06-15

    A new rapid and highly sensitive stability-indicating spectrofluorimetric method was developed for the determination of two stereoisomers anticancer drugs, doxorubicin (DOX) and epirubicin (EPI) in pure form and in pharmaceutical preparations. The fluorescence spectral behavior of DOX and EPI in a sodium dodecyl sulfate (SDS) micellar system was investigated. It was found that the fluorescence intensity of DOX and EPI in an aqueous solution of phosphate buffer pH4.0 and in the presence of SDS was greatly (about two fold) enhanced and the mechanism of fluorescence enhancement effect of SDS on DOX was also investigated. The fluorescence intensity of DOX or EPI was measured at 553nm after excitation at 497nm. The plots of fluorescence intensity versus concentration were rectilinear over a range of 0.03-2μg/mL for both DOX and EPI with good correlation coefficient (r>0.999). High sensitivity to DOX and EPI was attained using the proposed method with limits of detection of 10 and 9ng/mL and limits of quantitation of 29 and 28ng/mL, for DOX and EPI, respectively. The method was successfully applied for the determination of DOX and EPI in biological fluids and in their commercial pharmaceutical preparations and the results were concordant with those obtained using a previously reported method. The application of the proposed method was extended to stability studies of DOX following different forced degradation conditions (acidic, alkaline, oxidative and photolytic) according to ICH guidelines. Moreover, the kinetics of the alkaline and oxidative degradation of DOX was investigated and the apparent first-order rate constants and half-life times were calculated. PMID:27045788

  9. RBC indices

    MedlinePlus

    ... corpuscular hemoglobin concentration (MCHC); Mean corpuscular volume (MCV); Red blood cell indices ... and hemoglobin. The MCV reflects the size of red blood cells. The MCH and MCHC reflect the ...

  10. Position indicator

    DOEpatents

    Tanner, David E.

    1981-01-01

    A nuclear reactor system is described in which a position indicator is provided for detecting and indicating the position of a movable element inside a pressure vessel. The movable element may be a valve element or similar device which moves about an axis. Light from a light source is transmitted from a source outside the pressure vessel to a first region inside the pressure vessel in alignment with the axis of the movable element. The light is redirected by a reflector prism to a second region displaced radially from the first region. The reflector prism moves in response to movement of the movable element about its axis such that the second region moves arcuately with respect to the first region. Sensors are arrayed in an arc corresponding to the arc of movement of the second region and signals are transmitted from the sensors to the exterior of the reactor vessel to provide indication of the position of the movable element.

  11. Food Fortification Stability Study

    NASA Technical Reports Server (NTRS)

    Sirmons, T. A.; Cooper, M. R.; Douglas, G. L.

    2016-01-01

    This study aims to assess the stability of vitamin content, sensory acceptability and color variation in fortified spaceflight foods over a period of 2 years. Findings will identify optimal formulation, processing, and storage conditions to maintain stability and acceptability of commercially available fortification nutrients. Changes in food quality are being monitored to indicate whether fortification affects quality over time (compared to the unfortified control), thus indicating their potential for use on long-duration missions.

  12. Geology and slope stability in selected parts of The Geysers geothermal resources area: a guide to geologic features indicative of stable and unstable terrain in areas underlain by Franciscan and related rocks

    SciTech Connect

    Bedrossian, T.L.

    1980-01-01

    The results of a 4-month study of various geologic and topographic features related to the stability of Franciscan terrain in The Geysers GRA are presented. The study consisted of investigations of geologic and topographic features, throughout The Geysers GRA, and geologic mapping at a scale of 1:12,000 of approximately 1500 acres (600 hectares) of landslide terrain within the canyon of Big Sulphur Creek in the vicinity of the Buckeye mine (see plate 1). The area mapped during this study was selected because: (1) it is an area of potential future geothermal development, and (2) it illustrates that large areas mapped as landslides on regional scales (McLaughlin, 1974, 1975b; McNitt, 1968a) may contain zones of varying slope stability and, therefore, should be mapped in more detail prior to development of the land.

  13. 46 CFR 178.210 - Stability information.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Stability information. 178.210 Section 178.210 Shipping... information. (a) Stability information (stability details indicated on the Certificate of Inspection, a... this section. Enough stability information, including stability calculations and assumptions made...

  14. Slope stability and stabilization methods

    SciTech Connect

    Abramson, L.W.; Lee, T.S.; Boyce, G.M.; Sharma, S.S.

    1995-12-01

    Slope stability can be a major problem during the construction of surface facilities. Cutting into existing ground disturbs the mechanics of the surrounding area, which can result in landslides and rock falls. This practical reference gives you the comprehensive information you need for slope stability analysis, suitable methods of analysis with and without the use of computers, and examples of common stability problems and stabilization methods for cuts and fills. It includes detailed discussions of methods used in slope stability analysis, including the Ordinary Method of Slices, Simplified Janbu Method, Simplified Bishop Method, Spencer`s Method, other limit equilibrium methods, numerical methods, total stress analysis, effective stress analysis, and the use of computer programs to solve problems. Chapters include: General Slope Stability Concepts; Engineering Geology Principles; Groundwater Conditions; Geologic Site Exploration; Laboratory Testing Interpretation; Slope Stability Concepts; Slope Stabilization Methods; and Design, Construction and Maintenance.

  15. Chromium and Genomic Stability

    PubMed Central

    Wise, Sandra S.; Wise, John Pierce

    2014-01-01

    Many metals serve as micronutrients which protect against genomic instability. Chromium is most abundant in its trivalent and hexavalent forms. Trivalent chromium has historically been considered an essential element, though recent data indicate that while it can have pharmacological effects and value, it is not essential. There are no data indicating that trivalent chromium promotes genomic stability and, instead may promote genomic instability. Hexavalent chromium is widely accepted as highly toxic and carcinogenic with no nutritional value. Recent data indicate that it causes genomic instability and also has no role in promoting genomic stability. PMID:22192535

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

    PubMed Central

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

    2008-01-01

    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 μ, 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 μg/ml. Mean recovery was 99.1% and 98.6% for bisoprolol fumarate and amlodipine besylate, respectively. PMID:20046793

  17. The operator's emotional stability

    NASA Technical Reports Server (NTRS)

    Zilberman, P. B.

    1975-01-01

    An attempt is made to provide a psychological interpretation of the concept of emotional stability in connection with other psychics qualities of an operator's personality. Emotional stability is understood as a person's capacity to control his emotional state for the purpose of maintaining the necessary level of work performance under extreme stress conditions. By modeling the operator's sensorimotor activity and by comparing the productivity indicators under ordinary conditions with those obtained during work involving an emotional load, the level of emotional stability can be determined.

  18. Membrane stabilizer

    DOEpatents

    Mingenbach, William A.

    1988-01-01

    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.

  19. Mass Spectrometric Identification of the Arginine and Lysine deficient Proline Rich Glutamine Rich Wheat Storage Proteins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tandem mass spectrometry (MS/MS) of enzymatic digest has made possible identification of a wide variety of proteins and complex samples prepared by such techniques as RP-HPLC or 2-D gel electrophoresis. Success requires peptide fragmentation to be indicative of the peptide amino acid sequence. The f...

  20. Automatic stabilization

    NASA Technical Reports Server (NTRS)

    Haus, FR

    1936-01-01

    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.

  1. Metallic alloy stability studies

    NASA Technical Reports Server (NTRS)

    Firth, G. C.

    1983-01-01

    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.

  2. Indications for ulnar head replacement.

    PubMed

    Berger, Richard A

    2008-08-01

    Implanting an endoprosthesis is a clinically proven means of reestablishing mechanical contact between the distal radius and ulna, thus providing the foundation for stability of the entire forearm. The indications for, contraindications to, and outcomes of ulnar head replacement are discussed, together with the underlying mechanics, pathomechanics of ulnar head excision, the theoretical basis for implant arthroplasty, and the designs that have been employed. PMID:18836608

  3. Membrane stabilizer

    DOEpatents

    Mingenbach, W.A.

    1988-02-09

    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.

  4. Stability of Aggressive Behavior.

    ERIC Educational Resources Information Center

    Eron, Leonard D.; Huesmann, L. Rowell

    As indicated by multiple measures (including overt criminal behavior), stability of aggressive behavior was investigated across 22 years for males and females in a variety of situations. Originally, subjects included the entire population enrolled in the third grade in a semi-rural county in New York State. The sample included approximately 870…

  5. Laser Stabilization

    SciTech Connect

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

    2010-01-01

    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.

  6. Phytotoxicity as an indicator of stability of broiler production residues.

    PubMed

    Mendes, P M; Becker, R; Corrêa, L B; Bianchi, I; Dai Prá, M A; Lucia, T; Corrêa, E K

    2016-02-01

    Beddings used for successive broiler lots act as substrate to absorb water and feed from the excreta and may be subsequently used as agricultural fertilizers. This study evaluated the physicochemical characteristics and the phytotoxicity of beddings used to raise five consecutive broiler lots in five aviaries. Samples were collected for beddings not used yet and for beddings used at each of the five broiler lots. Lettuce and cucumber seeds were considered as phytotoxicity bioindicators. As beddings were used for greater number of lots, N, Ca, K, Mg and P contents generally increased, but the C content decreased, the pH alkalinized and humidity was reduced (P < 0.05). The germination index for lettuce and cucumber seeds was reduced with increased bedding (P < 0.05). Beddings used for at least five broiler lots presented decreased C:N ratio and would not recommended for agricultural use due to its toxicity for both tested seeds. PMID:26686067

  7. Visual stability

    PubMed Central

    Melcher, David

    2011-01-01

    Our vision remains stable even though the movements of our eyes, head and bodies create a motion pattern on the retina. One of the most important, yet basic, feats of the visual system is to correctly determine whether this retinal motion is owing to real movement in the world or rather our own self-movement. This problem has occupied many great thinkers, such as Descartes and Helmholtz, at least since the time of Alhazen. This theme issue brings together leading researchers from animal neurophysiology, clinical neurology, psychophysics and cognitive neuroscience to summarize the state of the art in the study of visual stability. Recently, there has been significant progress in understanding the limits of visual stability in humans and in identifying many of the brain circuits involved in maintaining a stable percept of the world. Clinical studies and new experimental methods, such as transcranial magnetic stimulation, now make it possible to test the causal role of different brain regions in creating visual stability and also allow us to measure the consequences when the mechanisms of visual stability break down. PMID:21242136

  8. Stabilization of compactible waste

    SciTech Connect

    Franz, E.M.; Heiser, J.H. III; Colombo, P.

    1990-09-01

    This report summarizes the results of series of experiments performed to determine the feasibility of stabilizing compacted or compactible waste with polymers. The need for this work arose from problems encountered at disposal sites attributed to the instability of this waste in disposal. These studies are part of an experimental program conducted at Brookhaven National Laboratory (BNL) investigating methods for the improved solidification/stabilization of DOE low-level wastes. The approach taken in this study was to perform a series of survey type experiments using various polymerization systems to find the most economical and practical method for further in-depth studies. Compactible dry bulk waste was stabilized with two different monomer systems: styrene-trimethylolpropane trimethacrylate (TMPTMA) and polyester-styrene, in laboratory-scale experiments. Stabilization was accomplished by wetting or soaking compactible waste (before or after compaction) with monomers, which were subsequently polymerized. Three stabilization methods are described. One involves the in-situ treatment of compacted waste with monomers in which a vacuum technique is used to introduce the binder into the waste. The second method involves the alternate placement and compaction of waste and binder into a disposal container. In the third method, the waste is treated before compaction by wetting the waste with the binder using a spraying technique. A series of samples stabilized at various binder-to-waste ratios were evaluated through water immersion and compression testing. Full-scale studies were conducted by stabilizing two 55-gallon drums of real compacted waste. The results of this preliminary study indicate that the integrity of compacted waste forms can be readily improved to ensure their long-term durability in disposal environments. 9 refs., 10 figs., 2 tabs.

  9. Calculation of enviromental indices

    SciTech Connect

    1995-10-01

    This portion of the Energy Vision 2020 draft report discusses the development of environmental indices. These indices were developed to be a quantitative measure of characterizing how TVA power system operations and alternative energy strategies might affect the environment. All indices were calculated relative to the reference strategy, and for the environmental review, the reference strategy was `no action`.

  10. ECOLOGICAL INDICATOR OVERVIEW

    EPA Science Inventory

    The Ecological Indicator Program in NERL is developing indicators for two key purposes. The first is to characterize the biological condition of shallow streams and large rivers. The second is to develop diagnostic indicators to evaluate the causes of impairment to these commun...

  11. Stabilizing brokerage

    PubMed Central

    Stovel, Katherine; Golub, Benjamin; Milgrom, Eva M. Meyersson

    2011-01-01

    A variety of social and economic arrangements exist to facilitate the exchange of goods, services, and information over gaps in social structure. Each of these arrangements bears some relationship to the idea of brokerage, but this brokerage is rarely like the pure and formal economic intermediation seen in some modern markets. Indeed, for reasons illuminated by existing sociological and economic models, brokerage is a fragile relationship. In this paper, we review the causes of instability in brokerage and identify three social mechanisms that can stabilize fragile brokerage relationships: social isolation, broker capture, and organizational grafting. Each of these mechanisms rests on the emergence or existence of supporting institutions. We suggest that organizational grafting may be the most stable and effective resolution to the tensions inherent in brokerage, but it is also the most institutionally demanding. PMID:22198763

  12. STABILIZED OSCILLATOR

    DOEpatents

    Jessen, P.L.; Price, H.J.

    1958-03-18

    This patent relates to sine-wave generators and in particular describes a generator with a novel feedback circuit resulting in improved frequency stability. The generator comprises two triodes having a common cathode circuit connected to oscillate at a frequency and amplitude at which the loop galn of the circutt ls unity, and another pair of triodes having a common cathode circuit arranged as a conventional amplifier. A signal is conducted from the osciliator through a frequency selective network to the amplifier and fed back to the osciliator. The unique feature of the feedback circuit is the amplifier operates in the nonlinear portion of its tube characteristics thereby providing a relatively constant feedback voltage to the oscillator irrespective of the amplitude of its input signal.

  13. Energy-conservation indicators

    SciTech Connect

    Belzer, D.B.

    1982-06-01

    A series of Energy Conservation Indicators were developed for the Department of Energy to assist in the evaluation of current and proposed conservation strategies. As descriptive statistics that signify current conditions and trends related to efficiency of energy use, indicators provide a way of measuring, monitoring, or inferring actual responses by consumers in markets for energy services. Related sets of indicators are presented in some 30 one-page indicator summaries. Indicators are shown graphically, followed by several paragraphs that explain their derivation and highlight key findings. Indicators are classified according to broad end-use sectors: Aggregate (economy), Residential, Commercial, Industrial, and transportation. In most cases annual time series information is presented covering the period 1960 through 1981.

  14. Welding-Current Indicator

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    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.

  15. Chemical Calcium Indicators

    PubMed Central

    Paredes, R. Madelaine; Etzler, Julie C.; Watts, Lora Talley; Lechleiter, James D.

    2008-01-01

    Our understanding of the underlying mechanisms of Ca2+ signaling as well as our appreciation for its ubiquitous role in cellular processes and has been rapidly advanced, in large part, due to the development of fluorescent Ca2+ indicators. In this chapter, we discuss some of the most common chemical Ca2+ indicators that are widely used for the investigation of intracellular Ca2+ signaling. Advantages, limitations and relevant procedures will be presented for each dye including their spectral qualities, dissociation constants, chemical forms, loading methods and equipment for optimal imaging. Chemical indicators that are now available allow for intracellular Ca2+ detection over a very large range (<50 nM to >50 μM). Higher affinity indicators can be used to quantify Ca2+ levels in the cytosol while lower affinity indicators can be optimized for measuring Ca2+ in subcellular compartments with higher concentrations. Indicators can be classified into either single wavelength or ratiometric dyes. Both classes require specific lasers, filters, and/or detection methods that are dependent upon their spectral properties and both classes have advantages and limitations. Single wavelength indicators are generally very bright and optimal for Ca2+ detection when more than one fluorophore is being imaging. Ratiometric indicators can be calibrated very precisely and they minimize the most common problems associated with chemical Ca2+ indicators including uneven dye loading, leakage, photobleaching and changes in cell volume. Recent technical advances that permit in vivo Ca2+ measurements will also be discussed. PMID:18929663

  16. Educational Quality Indicators.

    ERIC Educational Resources Information Center

    McEwen, Nelly

    1993-01-01

    The Educational Quality Indicators initiative, a 3-year collaboration between Alberta Education and 12 school districts, generated 10 action research projects that developed educational indicator systems with a broad range of student outcomes, methods of data collection and interpretation, and outcomes reporting. Field testing of these systems…

  17. Indicators of CETA Performance.

    ERIC Educational Resources Information Center

    Borus, Michael E.

    1978-01-01

    A study to find valid indicators of the long-run effects of Comprehensive Employment and Training Act of 1973 (CETA) manpower programs that would meet prime sponsors' needs for short-term feedback indicated that the proxies being used were not strongly correlated with success in CETA programs. (MF)

  18. School Readiness Indicator Items.

    ERIC Educational Resources Information Center

    Calkins, Julia; Ling, Thomson; Moore, Eric; Halle, Tamara; Hair, Beth; Moore, Kris; Zaslow, Marty

    This report provides a compilation of indicators of school readiness used in national, state, and local surveys in the United States, delineating the advantages and disadvantages for each indicator. The report begins with a legend to assist in interpreting the tables and includes contact information for national and state surveys. The remainder of…

  19. Performance Indicators in Education.

    ERIC Educational Resources Information Center

    Hattie, John

    1990-01-01

    Higher education performance indicators are being increasingly used in the United Kingdom, United States, and Australia. A model of performance indicators was applied to departments of education in 17 Australian universities, ranking departments on inputs, processes, and outputs. Implications of various weighting schemes are discussed. Tables…

  20. Institutional Effectiveness Indicators.

    ERIC Educational Resources Information Center

    Parker, Lynn S.; And Others

    Prepared for discussion at a retreat of the board of trustees of Florida Community College at Jacksonville (FCCJ), this packet of materials identifies 31 indicators of institutional performance and assesses FCCJ in terms of those indicators for which data were available. First, the packet presents a flow chart which illustrates the model used by…

  1. Retractable Visual Indicator Assembly

    NASA Technical Reports Server (NTRS)

    Hackler, George R. (Inventor); Gamboa, Ronald J. (Inventor); Dominquez, Victor (Inventor)

    1998-01-01

    A retractable indicator assembly may be mounted on a container which transmits air through the container and removes deleterious gases with an activated charcoal medium in the container. The assembly includes: an elongate indicator housing has a chamber therein; a male adaptor with an external threads is used for sealing engagement with the container; a plug located at the upper end of the housing; a housing that includes a transparent wall portion for viewing at least a portion of the chamber; a litmus indicator, moveable by a retractable rod from a retracted position within the container to an extended position within the chamber of the housing; and an outer housing that is secured to the upper end of the rod, and protects the indicator housing while the litmus indicator is in its normally retracted position. The assembly may be manually manipulated between its extended position wherein the litmus indicator may be viewed through the transparent wall of the indicator housing, and a retracted position wherein the outer housing encloses the indicator housing and engages the exterior of the container.

  2. Temperature-indicating Paints

    NASA Technical Reports Server (NTRS)

    Penzig, F

    1939-01-01

    This report is an attempt at a new method of coating the surface of the cylinder with materials that undergo chemical change at definite temperatures as indicated by a change in color. In this way it was hoped that the substance itself would indicate directly the position of its isotherms, which in measurements with thermocouples requires a tedious amount of labor.

  3. Cobb's Red Cabbage Indicator.

    ERIC Educational Resources Information Center

    Cobb, Vicki

    1998-01-01

    Describes the use of an indicator made from the pigment in red cabbage. Cabbage is grated then soaked in water. When the water is a strong red, the cabbage is strained out. The cabbage-juice indicator is then used to test for acids and bases. Includes a list of good foods to test for acidity and alkalinity. (PVD)

  4. 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

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

    2013-09-01

    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 μm 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

  5. Tamper indicating bolt

    DOEpatents

    Blagin, Sergei V.; Barkanov, Boris P.

    2004-09-14

    A tamper-indicating fastener has a cylindrical body with threads extending from one end along a portion of the body, and a tamper indicating having a transducer for converting physical properties of the body into electronic data; electronics for recording the electronic data; and means for communicating the recorded information to a remote location from said fastener. The electronics includes a capacitor that varies as a function of force applied by the fastener, and non-volatile memory for recording instances when the capacitance varies, providing an indication of unauthorized access.

  6. Stability of climate reconstructions

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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

  7. Health expectancy indicators.

    PubMed Central

    Robine, J. M.; Romieu, I.; Cambois, E.

    1999-01-01

    An outline is presented of progress in the development of health expectancy indicators, which are growing in importance as a means of assessing the health status of populations and determining public health priorities. PMID:10083720

  8. Sustainability Indicators and Metrics

    EPA Science Inventory

    Sustainability is about preserving human existence. Indicators and metrics are absolutely necessary to provide at least a semi-quantitative assessment of progress towards or away from sustainability. Otherwise, it becomes impossible to objectively assess whether progress is bei...

  9. 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...

  10. Health Care Indicators

    PubMed Central

    Donham, Carolyn S.; Letsch, Suzanne W.; Maple, Brenda T.; Singer, Naphtale; Cowan, Cathy A.

    1991-01-01

    Contained in this regular feature of the journal is a section on each of the following four topics community hospital statistics; employment, hours, and earnings in the private health sector; 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 provide indicators of the direction and magnitude of health care costs prior to the availability of more comprehensive data. PMID:10112766

  11. Health Care Indicators

    PubMed Central

    Letsch, Suzanne W.; Maple, Brenda T.; Cowan, Cathy A.; Donham, Carolyn S.

    1991-01-01

    This regular feature of the journal includes a section on 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 provide indicators of the direction and magnitude of health care costs prior to the availability of more comprehensive data. PMID:10114933

  12. Health Care Indicators

    PubMed Central

    Cowan, Cathy A.; Letsch, Suzanne W.; Levit, Katharine R.; Maple, Brenda T.; Stewart, Madie W.

    1991-01-01

    This regular feature of the journal includes a section on each of the following four topics: community hospital statistics; employment, hours, and earnings in the private health sector; 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 provide indicators of the direction and magnitude of health care costs prior to the availability of more comprehensive data. PMID:10110874

  13. Health Care Indicators

    PubMed Central

    Maple, Brenda T.; Cowan, Cathy A.; Donham, Carolyn S.; Letsch, Suzanne W.

    1991-01-01

    This regular feature of the journal includes a section on 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 provide indicators of the direction and magnitude of health care costs prior to the availability of more comprehensive data. PMID:10122365

  14. Health Care Indicators

    PubMed Central

    Cowan, Cathy A.; Donham, Carolyn S.; Letsch, Suzanne W.; Maple, Brenda T.; Lazenby, Helen C.

    1992-01-01

    This regular feature of the journal includes a section on 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 provide indicators of the direction and magnitude of health care costs prior to the availability of more comprehensive data. PMID:10120177

  15. Stability of Metronidazole Suspensions.

    PubMed

    Donnelly, Ronald F; Ying, James

    2015-01-01

    Metronidazole is an antiprotozoal agent used in the treatment of bacterial and protozoal anaerobic infections. The objectives of this study were to develop concentrated metronidazole suspensions that are inexpensive and easy to prepare and determine the stability of these suspensions after storage in amber polyvinyl chloride bottles at room temperature (23°C) and under refrigeration (5°C). Metronidazole suspensions (50 mg/mL) were prepared from powder using Ora-Blend or simple syrup as the vehicles. Samples were collected in triplicate from each container on days 0, 7, 14, 28, 56, and 93. Samples were assayed using a high-performance liquid chromatography method that had been validated as stability indicating. Color, change in physical appearance, and pH were also monitored at each time interval. There was no apparent change in color or physical appearance. The pH values changed by less than 0.20 units over the 93 days. The stability of metronidazole suspensions compounded from United States Pharmacopeia powder using Ora-Blend or simple syrup and packaged in amber polyvinyl chloride bottles was determined to be 93 days when stored at either room temperature or under refrigeration. PMID:26714365

  16. Composite stabilizer unit

    DOEpatents

    Ebaugh, Larry R.; Sadler, Collin P.; Carter, Gary D.

    1992-01-01

    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.

  17. Aircraft control position indicator

    NASA Technical Reports Server (NTRS)

    Dennis, Dale V. (Inventor)

    1987-01-01

    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.

  18. Indicator Systems and Evaluation

    NASA Technical Reports Server (NTRS)

    Canright, Shelley; Grabowski, Barbara

    1995-01-01

    Participants in the workshop session were actively engaged in a hands-on, minds-on approach to learning about indicators and evaluation processes. The six hour session was broken down into three two hour sessions. Each session was built upon an instructional model which moved from general understanding to specific IITA application. Examples and practice exercises served to demonstrate tand reinforce the workshop concepts. Each successive session built upon the previous session and addressed the major steps in the evaluation process. The major steps covered in the workshop included: project descriptions, writing goals and objectives for categories, determining indicators and indicator systems for specific projects, and methods and issues of data collection. The workshop served as a baseline upon which the field centers will build during the summer in undertaking a comprehensive examination and evaluation of their existing K-12 education projects.

  19. Internationally Comparable Health Indices

    PubMed Central

    Meijer, Erik; Kapteyn, Arie; Andreyeva, Tatiana

    2013-01-01

    One of the most intractable problems in international health research is the lack of comparability of health measures across countries or cultures. We develop a cross-country measurement model for health in which functional limitations, self-reports of health, and a physical measure are interrelated to construct health indices. To establish comparability across countries, we define the measurement scales by the physical measure while other parameters vary by country to reflect cultural and linguistic differences in response patterns. We find significant cross-country variation in response styles of health reports along with variability in genuine health that is related to differences in national income. Our health indices achieve satisfactory reliability of about 80% and their gradients by age, income, and wealth for the most part show the expected patterns. Moreover, the health indices correlate much more strongly with income and net worth than self reported health measures. PMID:20572201

  20. Enzymatic temperature change indicator

    DOEpatents

    Klibanov, Alexander M.; Dordick, Jonathan S.

    1989-01-21

    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.

  1. 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...

  2. ZERO-TIME INDICATOR

    DOEpatents

    Sander, H.H.

    1960-08-30

    The travel time of a nuclear shock wave from its point of origin to a location can be determined accurately by an apparatus for noting and comparably recording both zerotime, as indicated by the electromagnetic transient associated with the nuclear detonation, and shock wave arrival time.

  3. Triboluminescent indicator system

    DOEpatents

    Goods, Steven H.; Dentinger, Paul M.; Whinnery, Jr., Leroy L.

    2003-06-24

    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.

  4. Fluorescent Gage Indication

    NASA Technical Reports Server (NTRS)

    Barns, C. E.; Gilbaugh, B. L.; Gin, B.; Holt, W. L.; Lesak, P.; Mancini, R.; Spencer, H. F.

    1985-01-01

    Transfer of dye shows quality of contact between two mating parts. Mating parts checked for fit by spreading fluorescent dye on one, making brief light contact with other, and looking (under UV light) for transferred dye. Dye offers greater visibility under ultraviolet illumination, allowing better indication of how precisely parts match and what areas interfere.

  5. "Healthy" Human Development Indices

    ERIC Educational Resources Information Center

    Engineer, Merwan; Roy, Nilanjana; Fink, Sari

    2010-01-01

    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…

  6. Trends & Indicators: Enrollment Period

    ERIC Educational Resources Information Center

    Harney, John O.

    2011-01-01

    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…

  7. Supersonic Wave Interference Affecting Stability

    NASA Technical Reports Server (NTRS)

    Love, Eugene S.

    1958-01-01

    Some of the significant interference fields that may affect stability of aircraft at supersonic speeds are briefly summarized. Illustrations and calculations are presented to indicate the importance of interference fields created by wings, bodies, wing-body combinations, jets, and nacelles.

  8. Quantifying Stability in Complex Networks: From Linear to Basin Stability

    NASA Astrophysics Data System (ADS)

    Kurths, Jürgen

    The human brain, power grids, arrays of coupled lasers and the Amazon rainforest are all characterized by multistability. The likelihood that these systems will remain in the most desirable of their many stable states depends on their stability against significant perturbations, particularly in a state space populated by undesirable states. Here we claim that the traditional linearization-based approach to stability is in several cases too local to adequately assess how stable a state is. Instead, we quantify it in terms of basin stability, a new measure related to the volume of the basin of attraction. Basin stability is non-local, nonlinear and easily applicable, even to high-dimensional systems. It provides a long-sought-after explanation for the surprisingly regular topologies of neural networks and power grids, which have eluded theoretical description based solely on linear stability. Specifically, we employ a component-wise version of basin stability, a nonlinear inspection scheme, to investigate how a grid's degree of stability is influenced by certain patterns in the wiring topology. Various statistics from our ensemble simulations all support one main finding: The widespread and cheapest of all connection schemes, namely dead ends and dead trees, strongly diminish stability. For the Northern European power system we demonstrate that the inverse is also true: `Healing' dead ends by addition of transmission lines substantially enhances stability. This indicates a crucial smart-design principle for tomorrow's sustainable power grids: add just a few more lines to avoid dead ends. Further, we analyse the particular function of certain network motifs to promote the stability of the system. Here we uncover the impact of so-called detour motifs on the appearance of nodes with a poor stability score and discuss the implications for power grid design. Moreover, it will be shown that basin stability enables uncovering the mechanism for explosive synchronization and

  9. MATLAB Stability and Control Toolbox Trim and Static Stability Module

    NASA Technical Reports Server (NTRS)

    Kenny, Sean P.; Crespo, Luis

    2012-01-01

    MATLAB Stability and Control Toolbox (MASCOT) utilizes geometric, aerodynamic, and inertial inputs to calculate air vehicle stability in a variety of critical flight conditions. The code is based on fundamental, non-linear equations of motion and is able to translate results into a qualitative, graphical scale useful to the non-expert. MASCOT was created to provide the conceptual aircraft designer accurate predictions of air vehicle stability and control characteristics. The code takes as input mass property data in the form of an inertia tensor, aerodynamic loading data, and propulsion (i.e. thrust) loading data. Using fundamental nonlinear equations of motion, MASCOT then calculates vehicle trim and static stability data for the desired flight condition(s). Available flight conditions include six horizontal and six landing rotation conditions with varying options for engine out, crosswind, and sideslip, plus three take-off rotation conditions. Results are displayed through a unique graphical interface developed to provide the non-stability and control expert conceptual design engineer a qualitative scale indicating whether the vehicle has acceptable, marginal, or unacceptable static stability characteristics. If desired, the user can also examine the detailed, quantitative results.

  10. LEADING WITH LEADING INDICATORS

    SciTech Connect

    PREVETTE, S.S.

    2005-01-27

    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.

  11. Stability of missile forces and defenses

    SciTech Connect

    Canavan, G.H.

    1997-04-01

    This note derives the exchange equation for mixes of missiles and defenses and discusses the impact on stability of varying their relative proportions. For fixed offenses increasing defenses decreases stability until first strikes fall to zero. The same is true of decreasing offenses for fixed defenses, although the decrease in indices is smaller. A judicious increase in defenses and decrease in offenses should effect that transition with minimum loss of stability.

  12. Health Care Indicators

    PubMed Central

    Donham, Carolyn S.; Maple, Brenda T.; Letsch, Suzanne W.

    1993-01-01

    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:25372246

  13. Tamper-indicating seal

    DOEpatents

    Fiarman, Sidney; Degen, Michael F.; Peters, Henry F.

    1985-01-01

    There is disclosed a tamper-indicating seal that permits in the field inspection and detection of tampering. Said seal comprises a shrinkable tube having a visible pattern of markings which is shrunk over the item to be sealed, and a second transparent tube, having a second visible marking pattern, which is shrunk over the item and the first tube. The relationship between the first and second set of markings produces a pattern so that the seal may not be removed without detection.

  14. Magnetic Location Indicator

    NASA Technical Reports Server (NTRS)

    Stegman, Thomas W.

    1992-01-01

    Ferrofluidic device indicates point of highest magnetic-flux density in workspace. Consists of bubble of ferrofluid in immiscible liquid carrier in clear plastic case. Used in flat block or tube. Axes of centering circle on flat-block version used to mark location of maximum flux density when bubble in circle. Device used to find point on wall corresponding to known point on opposite side of wall.

  15. Health Care Indicators

    PubMed Central

    Donham, Carolyn S.; Maple, Brenda T.; Letsch, Suzanne W.

    1993-01-01

    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

  16. Nitrogen enrichment weakens ecosystem stability through decreased species asynchrony and population stability in a temperate grassland.

    PubMed

    Zhang, Yunhai; Loreau, Michel; Lü, Xiaotao; He, Nianpeng; Zhang, Guangming; Han, Xingguo

    2016-04-01

    Biodiversity generally promotes ecosystem stability. To assess whether the diversity-stability relationship observed under ambient nitrogen (N) conditions still holds under N enriched conditions, we designed a 6-year field experiment to test whether the magnitude and frequency of N enrichment affects ecosystem stability and its relationship with species diversity in a temperate grassland. Results of this experiment showed that the frequency of N addition had no effect on either the temporal stability of ecosystem and population or the relationship between diversity and stability. Nitrogen addition decreased ecosystem stability significantly through decreases in species asynchrony and population stability. Species richness was positively associated with ecosystem stability, but no significant relationship between diversity and the residuals of ecosystem stability was detected after controlling for the effects of the magnitude of N addition, suggesting collinearity between the effects of N addition and species richness on ecosystem stability, with the former prevailing over the latter. Both population stability and the residuals of population stability after controlling for the effects of the magnitude of N addition were positively associated with ecosystem stability, indicating that the stabilizing effects of component populations were still present after N enrichment. Our study supports the theory predicting that the effects of environmental factors on ecosystem functioning are stronger than those of biodiversity. Understanding such mechanisms is important and urgent to protect biodiversity in mediating ecosystem functioning and services in the face of global changes. PMID:26511538

  17. Trapped particle stability for the kinetic stabilizer

    NASA Astrophysics Data System (ADS)

    Berk, H. L.; Pratt, J.

    2011-08-01

    A kinetically stabilized axially symmetric tandem mirror (KSTM) uses the momentum flux of low-energy, unconfined particles that sample only the outer end-regions of the mirror plugs, where large favourable field-line curvature exists. The window of operation is determined for achieving magnetohydrodynamic (MHD) stability with tolerable energy drain from the kinetic stabilizer. Then MHD stable systems are analysed for stability of the trapped particle mode. This mode is characterized by the detachment of the central-cell plasma from the kinetic-stabilizer region without inducing field-line bending. Stability of the trapped particle mode is sensitive to the electron connection between the stabilizer and the end plug. It is found that the stability condition for the trapped particle mode is more constraining than the stability condition for the MHD mode, and it is challenging to satisfy the required power constraint. Furthermore, a severe power drain may arise from the necessary connection of low-energy electrons in the kinetic stabilizer to the central region.

  18. Plutonium inventories for stabilization and stabilized materials

    SciTech Connect

    Williams, A.K.

    1996-05-01

    The objective of the breakout session was to identify characteristics of materials containing plutonium, the need to stabilize these materials for storage, and plans to accomplish the stabilization activities. All current stabilization activities are driven by the Defense Nuclear Facilities Safety Board Recommendation 94-1 (May 26, 1994) and by the recently completed Plutonium ES&H Vulnerability Assessment (DOE-EH-0415). The Implementation Plan for accomplishing stabilization of plutonium-bearing residues in response to the Recommendation and the Assessment was published by DOE on February 28, 1995. This Implementation Plan (IP) commits to stabilizing problem materials within 3 years, and stabilizing all other materials within 8 years. The IP identifies approximately 20 metric tons of plutonium requiring stabilization and/or repackaging. A further breakdown shows this material to consist of 8.5 metric tons of plutonium metal and alloys, 5.5 metric tons of plutonium as oxide, and 6 metric tons of plutonium as residues. Stabilization of the metal and oxide categories containing greater than 50 weight percent plutonium is covered by DOE Standard {open_quotes}Criteria for Safe Storage of Plutonium Metals and Oxides{close_quotes} December, 1994 (DOE-STD-3013-94). This standard establishes criteria for safe storage of stabilized plutonium metals and oxides for up to 50 years. Each of the DOE sites and contractors with large plutonium inventories has either started or is preparing to start stabilization activities to meet these criteria.

  19. On the crisis stability of a submarine deterrent

    SciTech Connect

    Canavan, G.H.

    1992-05-01

    Without defenses, stability indices fall monotonically as the number of submarine-launched ballistic missiles (SLBMs) is reduced. For few SLBMs, the favorable stability properties of the survivable SLBMs are masked by the unfavorable stability properties of the non-survivable land missiles. With ground-based interceptor (GBI) defenses, stability initially falls faster. The number of GBIs could be increased gradually to minimize their impact on stability.

  20. Tamper-indicating seal

    DOEpatents

    Fiarman, S.; Degen, M.F.; Peters, H.F.

    1982-08-13

    There is disclosed a tamper-indicating seal that permits in the field inspection and detection of tampering. Said seal comprises a shrinkable tube having a visible pattern of markings which is shrunk over th item to be sealed, and a second transparent tube, having a second visible marking pattern, which is shrunk over the item and the first tube. The relationship between the first and second set of markings produces a pattern so that the seal may not be removed without detection. The seal is particularly applicable to UF/sub 6/ cylinder valves.

  1. Life Span Personality Stability in Sibling Statuses.

    ERIC Educational Resources Information Center

    Rosenberg, B. G.

    Personality stability and change in sibling status in the one- and two-child-family are examined in this Study. Q-sort data were analyzed for the same 33 male and 34 female subjects during four periods of their lives-- early and late adolescence and early and middle adulthood. Results indicate that stability of personality was greatest during…

  2. Residential Stability and Academic Sense of Control

    ERIC Educational Resources Information Center

    Gigliotti, Richard J.

    1976-01-01

    Suggests that stability level of an individual and the community in which he operates is directly related to a child's sense of control and consequently his achievement in school. Findings indicate that for whites, community stability is positively and significantly related to sense of control, with the inverse for blacks. (Author/AM)

  3. Breathiness in Indic languages

    NASA Astrophysics Data System (ADS)

    Esposito, Christina; Khan, Sameeruddowla; Hurst, Alex

    2005-04-01

    Previous work on breathiness in Indic languages has focused on the acoustic properties of breathy oral stops in languages like Hindi ([bal] hair versus [bhal] forehead) or Bengali ([baSa] house versus [bhaSa] language). However, breathiness in Indic languages often extends to nasals (e.g., Marathi ([maar] beat versus [mhaar] a caste). It is unclear if languages such as Hindi and Bengali have breathy nasals in addition to breathy oral stops. This study addresses the following questions: (1) Are breathy nasals (Nh) acoustically different from N+h sequences, both in languages where they are phonemic and ones where they are not? (2) In sequences of a breathy stop and a modal nasal (e.g., Hindi [udhmi] naughty) where is the breathiness realized, if at all? To answer these questions, audio, aerodynamic, and electroglottographic recordings will be made of Hindi, Bengali, and Marathi speakers. It is hypothesized that acoustically breathy nasals in Hindi and Bengali will not be distinct from sequences of N+ h. We believe that this will also be true for the oral stops. In addition, it is believed that in sequences of breathy oral stop followed by a modal nasal (e.g., ChN), the breathiness will be produced on the nasal.

  4. Tamper indicating packaging

    SciTech Connect

    Baumann, M.J.; Bartberger, J.C.; Welch, T.D.

    1994-08-01

    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.

  5. Nonintegral Maslov indices

    SciTech Connect

    Friedrich, H.; Trost, J.

    1996-08-01

    The phase loss of a wave reflected by a smooth potential generally varies continuously from {pi} in the long-wave limit to {pi}/2 in the limit of short waves. Incorporating the corresponding nonintegral multiples of {pi}/2 as nonintegral Maslov indices in the formulation of the WKB approximation leads to a substantial improvement of accuracy when the conditions for applicability of the WKB method are violated only near the classical turning points. We demonstrate the efficacy of using nonintegral Maslov indices for a Woods-Saxon potential and a repulsive 1/{ital x}{sup 2} potential. The nonintegral Maslov index for a given 1/{ital x}{sup 2} potential yields far more accurate wave functions than the conventional Langer modification of the potential in conjunction with phase loss {pi}/2. The energy spectrum of the radial harmonic oscillator (including the centrifugal potential), which is reproduced exactly by the standard WKB method with the Langer modification, is also reproduced exactly without the Langer modification when the nonintegral Maslov index is used. We suggest a method for approximately calculating the nonintegral Maslov index near the long-wave limit from the decaying WKB wave function in the classically forbidden region. {copyright} {ital 1996 The American Physical Society.}

  6. Angle-indicating digital servo

    NASA Technical Reports Server (NTRS)

    Parra, G. T.

    1977-01-01

    Device determines position of capacitive pickup relative to gravity-stabilized inductive element. Self nulling bridge with digital readout is faster and more accurate than electromechanical equivalent.

  7. International energy indicators

    NASA Astrophysics Data System (ADS)

    Rossi, E., Jr.

    1981-12-01

    Data on international energy indicators were tabulated and graphically represented. The following data are presented: world crude oil production, 1974 to October 1981; OPEC crude oil productive capacity; world crude oil and refined product inventory levels, 1975 to October, 1981; oil consumption in OECD countries, 1975 to October 1981; USSR crude oil production and exports, 1975 to October 1981; free world and US nuclear electricity generation, 1973 to December, 1981 and current capacity. Specific US data presented are: US domestic oil supply, 1977 to June, 1981; US gross imports of crude oil and products, 1973 to October, 1981; landed cost of Saudi crude current and 1974 dollars; US coal trade, 1975 to September, 1981; US natural gas trade, 1981; and energy/GNP ratio.

  8. Trust in performance indicators?

    PubMed Central

    Davies, H. T.; Lampel, J.

    1998-01-01

    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

  9. Enhanced tamper indicator

    DOEpatents

    Garcia, Anthony R.; Johnston, Roger G.

    2003-07-08

    The present invention provides an apparatus and method whereby the reliability and tamper-resistance of tamper indicators can be improved. A flexible connector may be routed through a latch for an enclosure such as a door or container, and the free ends of the flexible connector may be passed through a first locking member and firmly attached to an insert through the use of one or more attachment members such as set screws. A second locking member may then be assembled in interlocking relation with the first locking member to form an interlocked assembly around the insert. The insert may have one or more sharp projections extending toward the first or second locking member so that any compressive force applied in an attempt to disassemble the interlocked assembly results in permanent, visible damage to the first or second locking member.

  10. Stability at low symmetric force levels

    SciTech Connect

    Canavan, G.H.

    1997-09-01

    At low force levels stability indices depend primarily on the number of vulnerable missiles and the number of weapons on them. The index reduces to a product of the number of vulnerable missiles and the differences between normalized second and first strikes by vulnerable weapons. As the number of weapons per vulnerable missile decreases, the index rapidly approaches stability. Further reductions in vulnerable and survivable missiles and weapons do not affect stability, although they do reduce first and second strikes. Modest weapon reconstitution degrades stability significantly.

  11. Precipitation Indices Low Countries

    NASA Astrophysics Data System (ADS)

    van Engelen, A. F. V.; Ynsen, F.; Buisman, J.; van der Schrier, G.

    2009-09-01

    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

  12. Entanglement–breaking indices

    SciTech Connect

    Lami, L.; Giovannetti, V.

    2015-09-15

    We study a set of new functionals (called entanglement–breaking indices) which characterize how many local iterations of a given (local) quantum channel are needed in order to completely destroy the entanglement between the system of interest over which the transformation is defined and an external ancilla. The possibility of contrasting the noisy effects introduced by the channel iterations via the action of intermediate (filtering) transformations is analyzed. We provide some examples in which our functionals can be exactly calculated. The differences between unitary and non-unitary filtering operations are analyzed showing that, at least for systems of dimension d larger than or equal to 3, the non-unitary choice is preferable (the gap between the performances of the two cases being divergent in some cases). For d = 2 (qubit case), on the contrary, no evidences of the presence of such gap is revealed: we conjecture that for this special case unitary filtering transformations are optimal. The scenario in which more general filtering protocols are allowed is also discussed in some detail. The case of a depolarizing noise acting on a two–qubit system is exactly solved in a general case.

  13. Workshop on Feedback Stabilization of MHD Stabilities

    SciTech Connect

    McGuire, K.; Kugel, H.; La Haye, R.; Mauel, M.; Nevins, W.; Prager, S.

    1996-12-31

    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.

  14. Solar Indices Forecasting Tool

    NASA Astrophysics Data System (ADS)

    Henney, Carl John; Shurkin, Kathleen; Arge, Charles; Hill, Frank

    2016-05-01

    Progress to forecast key space weather parameters using SIFT (Solar Indices Forecasting Tool) with the ADAPT (Air Force Data Assimilative Photospheric flux Transport) model is highlighted in this presentation. Using a magnetic flux transport model, ADAPT, we estimate the solar near-side field distribution that is used as input into empirical models for predicting F10.7(solar 10.7 cm, 2.8 GHz, radio flux), the Mg II core-to-wing ratio, and selected bands of solar far ultraviolet (FUV) and extreme ultraviolet (EUV) irradiance. Input to the ADAPT model includes the inferred photospheric magnetic field from the NISP ground-based instruments, GONG & VSM. Besides a status update regarding ADAPT and SIFT models, we will summarize the findings that: 1) the sum of the absolute value of strong magnetic fields, associated with sunspots, is shown to correlate well with the observed daily F10.7 variability (Henney et al. 2012); and 2) the sum of the absolute value of weak magnetic fields, associated with plage regions, is shown to correlate well with EUV and FUV irradiance variability (Henney et al. 2015). This work utilizes data produced collaboratively between Air Force Research Laboratory (AFRL) and the National Solar Observatory (NSO). The ADAPT model development is supported by AFRL. The input data utilized by ADAPT is obtained by NISP (NSO Integrated Synoptic Program). NSO is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under a cooperative agreement with the National Science Foundation (NSF). The 10.7 cm solar radio flux data service, utilized by the ADAPT/SIFT F10.7 forecasting model, is operated by the National Research Council of Canada and National Resources Canada, with the support of the Canadian Space Agency.

  15. Predicting vegetation-stabilized dune field morphology

    NASA Astrophysics Data System (ADS)

    Barchyn, Thomas E.; Hugenholtz, Chris H.

    2012-09-01

    The morphology of vegetation-stabilized dune fields on the North American Great Plains (NAGP) mostly comprises parabolic dunes; stabilized barchan and transverse dunes are rare, with the exception of transverse and barchan mega-dunes in the Nebraska Sand Hills. We present a hypothesis from a numerical dune field model explaining the vegetation-stabilized morphology of dunes under unidirectional wind. Simulations with a range of initial dune morphologies (closely-spaced transverse to disperse barchans) indicate that stabilized morphology is determined by the ratio of slipface deposition rate to deposition tolerance of vegetation. Slipface deposition rate is related to dune height, flux, and celerity. With a fixed depositional tolerance, large, slow-moving dunes have low slipface deposition rates and ‘freeze’ in place once vegetation is introduced. Relatively small, fast dunes have high slipface deposition rates and evolve into parabolic dunes, often colliding during stabilization. Our hypothesis could explain differences in stabilized morphology across the NAGP and elsewhere.

  16. Precipitation Indices Low Countries

    NASA Astrophysics Data System (ADS)

    van Engelen, A. F. V.; Ynsen, F.; Buisman, J.; van der Schrier, G.

    2009-09-01

    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

  17. High Stability Engine Control (HISTEC)

    NASA Technical Reports Server (NTRS)

    DeLaat, John C.; Southwick, Robert D.; Gallops, George W.

    1996-01-01

    Future aircraft turbine engines, both commercial and military, must be able to successfully accommodate expected increased levels of steady-state and dynamic engine-face distortion. The current approach of incorporating a sufficient component design stall margin to tolerate these increased levels of distortion would significantly reduce performance. The objective of the High Stability Engine Control (HISTEC) program is to design, develop, and flight demonstrate an advanced, high-stability, integrated engine control system that uses measurement-based, real-time estimates of distortion to enhance engine stability. The resulting distortion tolerant control reduces the required design stall margin, with a corresponding increase in performance and decrease in fuel burn. The HISTEC concept, consisting of a Distortion Estimation System and a Stability Management Control, has been designed and developed. The Distortion Estimation System uses a small number of high-response pressure sensors at the engine face to calculate indicators of the type and extent of distortion in real time. The Stability Management Control, through direct control of the fan and compressor pressure ratio, accommodates the distortion by transiently increasing the amount of stall margin available based on information from the Distortion Estimation System. Simulation studies have shown the HISTEC distortion tolerant control is able to successfully estimate and accommodate time-varying distortion. Currently, hardware and software systems necessary for flight demonstration of the HISTEC concept are being designed and developed. The HISTEC concept will be flight tested in early 1997.

  18. Stabilization of somatropin by heparin.

    PubMed

    Zamiri, Camellia; Groves, Michael J

    2005-05-01

    Somatropin, human growth hormone (hGH), is an unstable protein, posing challenging problems for its formulation and long-term stability. Since hGH formed insoluble adducts with heparin our aim was to evaluate heparin as a stabilizing agent for the drug. These adducts were characterized by particle diameter, tertiary structure variations and release studies. Studies were also carried out to determine the stability of hGH in the presence and absence of heparin by an interfacial denaturation method and real-time stability studies by measuring hGH activity and particle diameter. Moreover, biological activity of hGH and hGH/UH (unfractionated heparin) adducts was identified by daily subcutaneous injections to hypophysectomized rats. There was a decrease in mean hydrodynamic particle diameter of hGH/UH adducts with increased pH (54.4 to 12.2 nm from pH 3 to pH 7) indicating that the adducts were either dissociating or dissolving at high pH. Furthermore, second-derivative spectroscopy indicated that complexation of hGH with heparin did not cause a major disruption in the tertiary structure of hGH but decreased the hydrophilic environment around the tyrosine residues. Release of hGH from hGH/UH adducts was pH and ionic strength dependent with the highest release at pH 8 (93%) and lowest release at pH 3 (0%) over the first hour. Interfacial denaturation methods indicated that vortex agitation over 120 s resulted in no change in the optical density of hGH/UH adducts compared with a substantial increase for hGH alone at pH 6.8. Real-time stability studies over 93 days demonstrated that hGH/UH adducts at both pH 3 and 7 with an excess of heparin produced the highest percent of active hGH remaining in the solution at 4 degrees C and 37 degrees C. The higher stability of hGH/UH adducts with excess heparin compared with the stoichiometric ratio was also confirmed by particle size measurements during storage. The biological activity of these adducts was comparable with hGH alone

  19. Physicochemical characterization of native glycyl-l-histidyl-l-lysine tripeptide for wound healing and anti-aging: a preformulation study for dermal delivery.

    PubMed

    Badenhorst, Travis; Svirskis, Darren; Wu, Zimei

    2016-03-01

    This study investigates the physicochemical properties of glycyl-histidyl-lysine-copper (GHK-Cu) to support the development of a formulation for effective topical delivery. The solubility and distribution coefficients (log D) were investigated using conventional methods and GHK concentrations were quantified with a validated stability-indicating reversed phase high performance liquid chromatography (RP-HPLC) method. In addition, the stability of GHK-Cu under stressed conditions and the compatibility with some potential formulation components were assessed. The peptide was susceptible to hydrolytic cleavage under basic and oxidative stressors and to a lesser extent acidic stress with first-order degradation profiles. Surprisingly, the peptide was stable in water and in pH (4.5-7.4) buffers for at least two weeks at 60  °C. The HPLC in conjunction with mass spectrometry identified three key degradation products, one of which was the constituent amino acid histidine. The distribution coefficients in octanol-phosphate buffered saline indicated the highly hydrophilic nature of GHK-Cu with log D values between -2.38 and -2.49 at pH range of 4.5-7.4. Furthermore, GHK-Cu was compatible with Span 60 based niosomes but less stable in the presence of the negatively charged lipid dicetyl phosphate. In summary, the preformulation studies provided information useful to deliver the GHK-Cu complex by carrier. PMID:25384620

  20. Limits to Stability

    ERIC Educational Resources Information Center

    Cottey, Alan

    2012-01-01

    The author reflects briefly on what limited degree of global ecological stability and human cultural stability may be achieved, provided that humanity retains hope and does not give way to despair or hide in denial. These thoughts were triggered by a recent conference on International Stability and Systems Engineering. (Contains 5 notes.)