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1

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

PubMed Central

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

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

2014-01-01

2

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

PubMed

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

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

2014-01-01

3

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

PubMed Central

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 ?m) 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

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

2013-01-01

4

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

PubMed

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 ?m) 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

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

2013-12-01

5

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

PubMed Central

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 (250×4.6 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 ?g/ml. The method showed good recoveries (average 100.06%) and relative standard deviation for intra and inter-day were ? 1.5 %. The method was validated for specificity and robustness also. PMID:20502568

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

2009-01-01

6

Stability-indicating RP-HPLC method for the quantitative analysis of perindopril erbumine in tablet dosage form.  

PubMed

A specific, stability-indicating reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed and validated for the estimation of perindopril erbumine (PDE) in tablet dosage form. The HPLC method showed adequate separation of PDE from its degradation products. The separation was achieved on a Phenomenex Luna C18 column (250 × 4.6 mm × 5 µm) using a mobile phase composition of 0.2% trifluoroacetic acid buffer and acetonitrile in the ratio of 60:40 (pH adjusted to 3 with ammonia) at a flow rate of 1 mL/min. The injection volume was 20 µL and the wavelength of detection was kept at 215 nm. Stress studies were performed with 1 mg/mL of each drug, starting with mild conditions and followed by stronger conditions to achieve sufficient degradation at approximately 5-20%. The linearity of the proposed method was investigated in the range of 2.5 to 50 µg/mL for PDE. The limits of detection and quantification were found to be 0.75 and 2.3 µg/mL, respectively. PMID:23690066

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

2014-04-01

7

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

PubMed

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-C(18), Lichrosphere-100(®) (250 mm × 4.6 mm i.d., particle size 5 ?m) 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 ?l 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 ?g/ml and 20-240 ?g/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

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

2012-01-01

8

Validated stability-indicating assay method for simultaneous determination of aceclofenac and thiocolchicoside using RP-HPLC.  

PubMed

A rapid, accurate, precise, robust and specific stability indicating RP-HPLC method has been developed and validated for simultaneous determination of fixed dose combination of Aceclofenac (ACF) and Thiocolchicoside (THC). Combinations and marketed tablets were subjected to stress conditions such as oxidation, hydrolysis, photolysis and heat. Successful separation of drugs from stress degradation products was achieved on Kromasil C18 (250 × 4.6 mm, 5 ?m) column at 30 °C using gradient mobile phase system consisting of (A) 10 mM ammonium acetate pH 5.00 buffer and (B) acetonitrile: water (70:30 v/v). The flow rate was 1.0 mL/min with UV detection at 265 nm. The retention time of THC and ACF was 13.29 and 22.20 min respectively. Peak purity of both the drugs was passing in all degradation conditions demonstrates the specificity of assay method for their estimation in presence of degradation products. The developed HPLC method was validated for linearity, accuracy, precision and robustness. The linearity of the proposed method was investigated in the range of 80-280 µg/mL for ACF and 6.4-22.4 µg/mL for THC. The utility of the procedure was verified by its application to marketed formulations. PMID:24310363

Samanthula, G; Shrigod, V V; Patel, P N

2014-08-01

9

Stability-indicating RP-HPLC method for the simultaneous determination of escitalopram oxalate and clonazepam.  

PubMed

The objective of the current study was to develop a validated, specific stability-indicating reversed-phase liquid chromatographic (LC) method for the quantitative determination of escitalopram oxalate and clonazepam and their related substances in bulk drugs and pharmaceutical dosage forms in the presence of degradation products. Forced degradation studies were performed on the pure drugs of escitalopram oxalate and clonazepam, as per the stress conditions prescribed by the International Conference on Harmonization (ICH) using acid, base, oxidation, thermal stress and photolytic degradation to show the stability-indicating power of the method. Significant degradation was observed during acid and alkaline hydrolysis and no degradation was observed in other stress conditions. The chromatographic method was optimized using the samples generated from forced degradation studies. Good resolution between the peaks corresponded to the active pharmaceutical ingredients, escitalopram oxalate and clonazepam, and degradation products from the analyte were achieved on an ODS Hypersil C18 column (250 × 4.6 mm) using a mobile phase consisting of a mixture of acetonitrile-50 mM phosphate buffer + 10 mM triethylamine (70:30, v/v). The detection was conducted at 268 nm. The limit of detection and the limit of quantitation for escitalopram oxalate and clonazepam were established. The stress test solutions were assayed against the qualified working standards of escitalopram oxalate and clonazepam, which indicated that the developed LC method was stability-indicating. Validation of the developed LC method was conducted as per ICH requirements. The developed LC method was found to be suitable to check the quality of bulk samples of escitalopram oxalate and clonazepam. PMID:23135233

Kakde, Rajendra B; Satone, Dinesh D; Gadapayale, Kamalesh K; Kakde, Megha G

2013-07-01

10

Development and Validation of Stability-indicating RP-HPLC Method for Estimation of Pamabrom in Tablets.  

PubMed

The present study depicts the development of a validated RP-HPLC method for the determination of the pamabrom in presence of degradation products or other pharmaceutical excipients. Stress study was performed on pamabrom and it was found that it degrade sufficiently in acidic, alkali and oxidative condition but less degradation was found in thermal and photolytic condition. The separation was carried out on Enable G 120 A(0) (250×4.6 mm, 5 ?) column having particle size 5 ? using methanol: water (75:25 v/v) with pH 4.0 adjusted with ortho phosphoric acid as mobile phase at flow rate of 1 ml/min. The wavelength of the detection was 280nm. A retention time (Rt) nearly 3.9 min was observed. The calibration curve for pamabrom was linear (r (2) = 0.9997) from range of 10-60 ?g/ml with limit of detection and limit of quantification of 1.41 ?g/ml and 4.28 ?g/ml, respectively. Analytical validation parameter 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 101.35%. Thus, the developed RP-HPLC method was found to be suitable for the determination of pamabrom in bulk as well as stability samples of tablets containing various excipients. PMID:25035530

Shah, U; Kavad, M; Raval, M

2014-05-01

11

Development and Validation of Stability-indicating RP-HPLC Method for Estimation of Pamabrom in Tablets  

PubMed Central

The present study depicts the development of a validated RP-HPLC method for the determination of the pamabrom in presence of degradation products or other pharmaceutical excipients. Stress study was performed on pamabrom and it was found that it degrade sufficiently in acidic, alkali and oxidative condition but less degradation was found in thermal and photolytic condition. The separation was carried out on Enable G 120 A0 (250×4.6 mm, 5 ?) column having particle size 5 ? using methanol: water (75:25 v/v) with pH 4.0 adjusted with ortho phosphoric acid as mobile phase at flow rate of 1 ml/min. The wavelength of the detection was 280nm. A retention time (Rt) nearly 3.9 min was observed. The calibration curve for pamabrom was linear (r2 = 0.9997) from range of 10-60 ?g/ml with limit of detection and limit of quantification of 1.41 ?g/ml and 4.28 ?g/ml, respectively. Analytical validation parameter 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 101.35%. Thus, the developed RP-HPLC method was found to be suitable for the determination of pamabrom in bulk as well as stability samples of tablets containing various excipients. PMID:25035530

Shah, U.; Kavad, M.; Raval, M.

2014-01-01

12

Determination of stress-induced degradation products of cetirizine dihydrochloride by a stability-indicating RP-HPLC method.  

PubMed

BackgroundA new, simple and accurate stability-indicating reverse phase high performance liquid chromatography method was developed and validated during the early stage of drug development of an oral lyophilizate dosage form of cetirizine dihydrochloride.MethodsFor RP-HPLC analysis it was used an Eclipse XDB C8 column 150 mm × 4.6 mm, 5 ¿m (Agilent columns, Barcelona, Spain) as the stationary phase with a mobile phase consisted of a mixture of 0.2 M K2HPO4 pH 7.00 and acetonitrile (65:35, v/v) at a flow rate of 1 mL min ¿1. Detection was performed at 230 nm using diode array detector. The method was validated in accordance with ICH guidelines with respect to linearity, accuracy, precision, specificity, limit of detection and quantification.ResultsThe method results in excellent separation between the drug substance and its stress-induced degradation products. The peak purity factor is >950 for the drug substance after all types of stress, which confirms the complete separation of the drug substance peak from its stress induced degradation products.Regression analysis showed r2¿>¿0.999 for cetirizine dihydrochloride in the concentration range of 650 ¿g mL ¿1 to 350 ¿g mL¿1 for drug substance assay and a r2¿>¿0.999 in the concentration range of 0.25 ¿g mL¿1 to 5 ¿g mL¿1 for degradation products. The method presents a limit of detection of 0.056 ¿g mL ¿1 and a limit of quantification of 0.25 ¿g mL¿1. The obtained results for precision and accuracy for drug substance and degradation products are within the specifications established for the validation of the method.ConclusionsThe proposed stability-indicating method developed in the early phase of drug development proved to be a simple, sensitive, accurate, precise, reproducible and therefore useful for the following stages of the cetirizine dihydrochloride oral lyophilizate dosage form development. PMID:25487685

Flórez Borges, Paloma; Pérez Lozano, Pilar; García Montoya, Encarna; Miñarro, Montserrat; Ticó, Josep R; Jo, Enric; Suñe Negre, Josep M

2014-12-01

13

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 Central

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

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

2013-01-01

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

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

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

2013-06-01

15

Development and Validation of a Stability-Indicating RP-HPLC Method for Duloxetine Hydrochloride in its Bulk and Tablet Dosage Form  

PubMed Central

The objective of the present work was to develop a stability-indicating RP-HPLC method for duloxetine hydrochloride (DUL) in the presence of its degradation products generated from forced decomposition studies. The drug substance was found to be susceptible to stress conditions of acid hydrolysis. The drug was found to be stable to dry heat, photodegradation, oxidation and basic condition attempted. Successful separation of the drug from the degradation products formed under acidic stress conditions was achieved on a Hypersil C-18 column (250 mm × 4.6 mm id, 5?m particle size) using acetonitrile: 0.01 M potassium dihydrogen phosphate buffer (pH 5.4 adjusted with orthophosphoric acid) (50:50, v/v) as the mobile phase at a flow rate of 1.0 ml/min. Quantification was achieved with photodiode array detection at 229 nm over the concentration range 1–25 ?g/ml with range of recovery 99.8–101.3 % for DUL by the RP-HPLC method. Statistical analysis proved the method to be repeatable, specific, and accurate for estimation of DUL. It can be used as a stability-indicating method due to its effective separation of the drug from its degradation products, PMID:21179321

Chhalotiya, Usmangani K.; Bhatt, Kashyap K.; Shah, Dimal A.; Baldania, Sunil L.

2010-01-01

16

Optimization and validation of a stability-indicating RP-HPLC method for determination of azithromycin and its related compounds.  

PubMed

A validated stability-indicating HPLC method was developed for the analysis of azithromycin (AZ) and its related compounds in raw materials, capsule, and suspension using an Xterra RP C18 column at 50 degrees C with UV detection at 215 nm. Isocratic elution was employed using the mobile phase 14 mM disodium hydrogen phosphate (pH 10.5, adjusted by 1 M NaOH)-methanol-acetonitrile-tetrahydrofuran (40.0 + 30.0 + 30.0 + 0.1, v/v/v/v). AZ and 14 of its related compounds were separated and quantified. The described method was linear over the range of 2-1800 microg/mL AZ with (r = 0.9999). The stability of AZ was studied under accelerated acidic, alkaline, and oxidative conditions. The proposed method was used to investigate the kinetics of acidic and alkaline hydrolysis process of AZ at different temperatures, and the apparent pseudo first-order rate constant, half-life, and activation energy were calculated. The major peak detected from the degradation of AZ in alkaline and acidic conditions was decladinosylazithromycine, while azithromycin N-oxide was detected from the oxidative degradation. Long-term stability studies for capsule and oral suspension were carried out. The proposed stability-indicating method was completely validated according to the U.S. Food and Drug Administration requirements. PMID:21563685

El-Gindy, Alaa; Attia, Khalid A; Nassar, Mohammad Wafaa; Al Abasawi, Nasr M; Al-Shabrawi, Maisra

2011-01-01

17

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

PubMed

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

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

2014-09-01

18

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

PubMed

A new stability-indicating high-performance liquid chromatographic method for simultaneous analysis of sitagliptin and simvastatin in pharmaceutical dosage form was developed and validated. The mobile phase consisted of methanol and water (70:30, v/v) with 0.2 % of n-heptane sulfonic acid adjusted to pH 3.0 with ortho phosphoric acid was used. Retentions of sitagliptin and simvastatin were 4.3 min and 30.4 min, respectively with a flow rate of 1 ml/min on C8 (Qualisil BDS, 250×4.6 mm, 5 ?). Eluents were detected at 253 nm using photodiode diode array detector. The linear regression analysis data for the linearity plot showed correlation coefficient values of 0.9998 and 0.9993 for sitagliptin and simvastatin, with respective concentration ranges of 20-150 ?g/ml and 8-60 ?g/ml. The relative standard deviation for inter-day precision was lower than 2.0%. The assay of sitagliptin and simvastatin was determined in tablet dosage form was found to be within limits. Both drugs were subjected to a variety of stress conditions such as acidic, basic, oxidation, photolytic, neutral and thermal stress in order to achieve adequate degradation. Results revealed that considerable degradation was found in all stress conditions except oxidative degradations. The method has proven specificity for stability indicating assay method. PMID:25425754

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

2014-09-01

19

Development and Validation of a Stability-Indicating RP-HPLC Method for the Quantitative Analysis of Anagrelide Hydrochloride.  

PubMed

A simple, rapid, and stability-indicating reverse-phase liquid chromatographic assay method was developed for Anagrelide Hydrochloride (ANG) in the presence of its degradation products generated from forced decomposition studies. The HPLC separation was achieved on a C18 Inertsil column (250 mm × 4.6 mm i.d. particle size is 5 ?m), using solution A, a mixture of 0.03 M potassium di-hydrogen phosphate pH-adjusted to 3.0 using ortho-phosphoric acid (buffer): methanol: acetonitrile (90:5:5, v/v/v), and solution B, which contains a mixture of buffer: acetonitrile (10:90, v/v). The UV detector was operated at 251 nm while column temperature was maintained at 40°C, and the gradient program had the flow rate of 1.0 mL min(-1). The developed method was validated as per ICH guidelines with respect to specificity, linearity, precision, accuracy, robustness, and limit of quantification. The method was found to be simple, specific, precise, accurate, and reproducible. Selectivity was validated by subjecting the stock solution of ANG to acidic, basic, photolysis, oxidative, and thermal degradation. The calibration curve was found to be linear in the concentration range of 0.05-152 ?g mL(-1) (R(2) = 0.9991). The peaks of degradation products did not interfere with that of pure ANG. The utility of the developed method was examined by analyzing the tablets containing ANG. PMID:23008806

Pujeri, Sudhakar S; Khader, Addagadde M A; Seetharamappa, Jaldappagari

2012-09-01

20

Development and Validation of a Stability-Indicating RP-HPLC Method for the Quantitative Analysis of Anagrelide Hydrochloride  

PubMed Central

A simple, rapid, and stability-indicating reverse-phase liquid chromatographic assay method was developed for Anagrelide Hydrochloride (ANG) in the presence of its degradation products generated from forced decomposition studies. The HPLC separation was achieved on a C18 Inertsil column (250 mm × 4.6 mm i.d. particle size is 5 ?m), using solution A, a mixture of 0.03 M potassium di-hydrogen phosphate pH-adjusted to 3.0 using ortho-phosphoric acid (buffer): methanol: acetonitrile (90:5:5, v/v/v), and solution B, which contains a mixture of buffer: acetonitrile (10:90, v/v). The UV detector was operated at 251 nm while column temperature was maintained at 40°C, and the gradient program had the flow rate of 1.0 mL min?1. The developed method was validated as per ICH guidelines with respect to specificity, linearity, precision, accuracy, robustness, and limit of quantification. The method was found to be simple, specific, precise, accurate, and reproducible. Selectivity was validated by subjecting the stock solution of ANG to acidic, basic, photolysis, oxidative, and thermal degradation. The calibration curve was found to be linear in the concentration range of 0.05–152 ?g mL?1 (R2 = 0.9991). The peaks of degradation products did not interfere with that of pure ANG. The utility of the developed method was examined by analyzing the tablets containing ANG. PMID:23008806

Pujeri, Sudhakar S.; Khader, Addagadde M. A.; Seetharamappa, Jaldappagari

2012-01-01

21

Development and validation of a stability-indicating RP-HPLC assay method and stress degradation studies on dapiprazole.  

PubMed

Dapiprazole (DPZ) was subjected to different stress conditions prescribed by the International Conference on Harmonization. A stability-indicating high-performance liquid chromatography method was developed for the analysis of the drug in the presence of its degradation products. The degradation was found to occur in hydrolytic, and to some extent, photolytic conditions, however, the drug was stable to oxidative and thermal stress. The drug was particularly labile under neutral and alkaline hydrolytic conditions. The assay was involved an isocratic elution of DPZ in a Kromasil 100C18 column using a mobile phase composition of water (pH 6.5, 0.05%, w/v, 1-heptane sulfonic acid) and acetonitrile (40:60, v/v). The flow rate was 0.8 mL/min and the detection was conducted at 246 nm. The assay method was found to be linear from 5 to 30 µg/mL. The method was validated for linearity, range, precision, accuracy, specificity, selectivity, limit of detection and limit of quantitation. PMID:23169931

Ramesh, Thippani; Rao, Pothuraju Nageswara

2013-10-01

22

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

PubMed

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

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

2014-03-01

23

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

PubMed Central

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

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

2014-01-01

24

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

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 ?m) 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 ?g/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

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

2012-01-01

25

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

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, 3.5?) 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 ?g/mL, 0.18-62.36 ?g/mL, 0.17-6.26 ?g/mL, 0.47-31.22 ?g/mL, and 0.44-30.45 ?g/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

Roy, Chinmoy; Chakrabarty, Jitamanyu

2013-12-01

26

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

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, 3.5?) 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 ?g/mL, 0.18–62.36 ?g/mL, 0.17–6.26 ?g/mL, 0.47–31.22 ?g/mL, and 0.44–30.45 ?g/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

Roy, Chinmoy; Chakrabarty, Jitamanyu

2013-01-01

27

Development and Validation of Rapid Stability-Indicating RP-HPLC-DAD Method for the Quantification of Lapatinib and Mass Spectrometry Analysis of Degraded Products.  

PubMed

A rapid, simple and stability-indicating high-performance liquid chromatography assay method was developed and validated for quantitative analysis of lapatinib (LPT) in bulk pharmaceuticals. The newly developed method was assessed using a C18 MZ-Analytical column (5 µm, 150 × 4.6 mm, OSD-3), which was protected by a (5 µm, 4.0 × 4.6 mm, OSD-3) pre-column with mobile phase that was composed of acetonitrile and water (70/30, v/v) and a detection wave length of 227 nm. The method was validated according to the ICH guidelines with respect to precision, accuracy, linearity, robustness, specificity and system suitability. Forced degradation studies were also performed for LPT to determine the stability-indicating aspect of developed method. The method was found to be specific for LPT in the presence of degradation products. The retention time of LPT was ?4 min. Accuracy of the method was found to be 2.20% bias for all tested samples. The inter- and intra-day precision of the novel method were found to be 2.84 and 2.78%, respectively. The calibration curve was linear over the concentration range of 5-80 µg/mL with a regression coefficient of 0.9990. The limits of detection and quantification were also found to be 1 and 5 µg/mL, respectively. Mass spectrometry analysis was performed in order to better characterize degraded products. PMID:25491314

Saadat, Ebrahim; Dehghan Kelishady, Pooya; Ravar, Fatemeh; Kobarfard, Farzad; Dorkoosh, Farid A

2014-12-01

28

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

PubMed

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

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

2013-03-01

29

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

PubMed Central

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

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

2013-01-01

30

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

PubMed Central

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

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

2011-01-01

31

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

PubMed

Obtained benzimidazole derivatives, our next synthesized heterocyclic compounds, belong to a new group of chemical bondings with potential anticancer properties (B?aszczak-?wi?tkiewicz & Mikiciuk-Olasik, 2006, J Liguid Chrom Rel Tech 29: 2367-2385; B?aszczak-?wi?tkiewicz & Mikiciuk-Olasik, 2008, Wiad Chem 62: 11-12, in Polish; B?aszczak-?wi?tkiewicz & 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 ?g/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

B?aszczak-?wi?tkiewicz, Katarzyna; Mirowski, Marek; Kapli?ska, Katarzyna; Kruszy?ski, Rafa?; Trz?sowska-Kruszy?ska, Agata; Mikiciuk-Olasik, El?bieta

2012-01-01

32

Validation of assay indicating method development of meloxicam in bulk and some of its tablet dosage forms by RP-HPLC.  

PubMed

A novel, simple and economic reverse phase high performance liquid chromatography (RP-HPLC) method has been developed for the quantification of Meloxicam in bulk and tablet dosage form with greater precision and accuracy. Separation was achieved on Develosil ODS HG-5 RP C18, (15 cm?×?4.6 mm i.d. 5 ?m) column in isocratic mode with mobile phase consisting of acetonitrile: phosphate buffer(pH 3.4) (60:40) with a flow rate of 1 mL/min. The detection was carried out at 268 nm. The retention time of Meloxicam was found to be 2.09 min. The method was validated as per ICH guidelines. Linearity was established for Meloxicam in the range 20 - 120 ?g/ml with R(2) value 0.996. The percentage recovery of Meloxicam was found to be in the range 99.99-100.46%. The high recovery and low relative standard deviation confirm the suitability of the proposed method for the estimation of the drug in bulk and tablet dosage forms. Validation studies demonstrated that the proposed RP-HPLC method is simple, specific, rapid, reliable and reproducible for the determination of Meloxicam for Quality Control level. PMID:24711980

Sahoo, Nalini Kanta; Sahu, Madhusmita; Rao, Podilapu Srinivasa; Rani, N Sandhya; Devi, Jnv Indira; Ghosh, Goutam

2014-01-01

33

Stability-Indicating RP-HPLC Method for the Simultaneous Determination of Prazosin, Terazosin, and Doxazosin in Pharmaceutical Formulations  

PubMed Central

The current study was carried out with an attempt to separate similarly structured title drugs by liquid chromatography. Spectrophotometric techniques were generally insufficient under these conditions because of the spectral overlapping of drugs with similar functional groups. The pharmaceutical drugs prazosin, terazosin, and doxazosin contain the same parent quinazoline nucleus, thus making it especially difficult to separate the former two drugs because of their very similar structures. A simple and sensitive method for the routine determination of these drugs in pharmaceutical formulations was attempted. We found that the mobile phase consisting of A: ACN–diethylamine (0.05 ml), B: methanol, and C: 10 mM Ammonium acetate separated these drugs effectively. Separations were carried out on a new Kromasil C18 column (250 × 4.6 mm, 5.0 ?m) at 254 nm wavelength. The calibration curve was found to be linear in the range of 2–500 ?g/ml. The stated method was then validated in terms of specificity, linearity, precision, and accuracy. Additionally, the proposed method reduced the duration of the analysis. PMID:23008810

Shrivastava, Alankar; Gupta, Vipin B.

2012-01-01

34

Stability Indicating RP-HPLC Method for Simultaneous Determination of Simvastatin and Ezetimibe from Tablet Dosage Form  

PubMed Central

A simple, specific and sensitive reverse phase high performance liquid chromatographic method was developed and validated for simultaneous determination of ezetimibe and simvastatin from pharmaceutical dosage forms. The method uses C18 ODS Hypersil column and isocratic elution. The mobile phase composed of acetonitrile:phosphate buffer (pH 4.5, 0.01M) in the ratio of 65:35 v/v was used at a flow rate of 1.0 ml /min. UV detector was programmed at 232 nm for first 10 min and at 238 nm for 10 to 20 min. All the validation parameters were in acceptable range. The developed method was effectively applied to quantitate amount of ezetimibe and simvastatin from tablets. The method was also applied suitably for determining the degradation products of ezetimibe and simvastatin. PMID:20838524

Dixit, R. P.; Barhate, C. R.; Padhye, S. G.; Viswanathan, C. L.; Nagarsenker, M. S.

2010-01-01

35

Determination of methylparaben, propylparaben, triamcinolone acetonide and its degradation product in a topical cream by RP-HPLC  

Microsoft Academic Search

A novel reversed-phase high-performance liquid chromatographic (RP-HPLC) method was developed and validated for the determination of active component triamcinolone acetonide, its degradation product triamcinolone (occurring in formulation after long-term stability tests) and two preservatives presented in the cream—methylparaben and propylparaben, using hydrocortisone as an internal standard.

L. Matysová; R. Hájková; J. Šícha; P. Solich

2003-01-01

36

Optimization of separation and determination of moxifloxacin and its related substances by RP-HPLC.  

PubMed

A RP-HPLC method for the separation and determination of impurities of moxifloxacin, in its pharmaceutical forms as well as moxifloxacin degradation products, was developed with the aid of DryLab software and chemometric (response surface) approach. The separation of four synthesis-related impurities was achieved on a Waters C(18) XTerra column using a mobile phase of (water+triethylamine (2%, v/v)): acetonitrile=90:10 (v/v%); the pH of water phase being adjusted with phosphoric acid to 6.0. Flow rate of the mobile phase was 1.5 ml/min and UV detection at 290 nm was employed. The column was thermostated at 45 degrees C. The resolution between the two least resolved impurity peaks was in average, R(s,min) > 1.5. Method validation parameters indicate linear dynamic range 0.2-2.0 microg/ml with LOQ ca. 0.20 microg/ml and LOD ca. 0.05 microg/ml for all analytes. The method was applied for the impurities determination in drug tablets and infusion (Avelox), Bayer AG) and for degradation products determination in a stability study of moxifloxacin. The impurity content in the tablets and infusion was quantified as 0.1% of total drug. Two degradation products were noted under hydrolytic conditions. The method can also be used for rapid and accurate quantification of moxifloxacin hydrochloride in its tablets during stability testing. PMID:19464135

Djurdjevic, Predrag; Ciric, Andrija; Djurdjevic, Aleksandra; Stankov, Milena Jelikic

2009-09-01

37

Development and validation of RP-HPLC method for estimation of Cefotaxime sodium in marketed formulations.  

PubMed Central

A RP-HPLC assay method has been developed and validated for cefotaxime. An isocratic RP-HPLC was developed on a SS Wakosil II- C8 column (250 mm ˜4.6 mm i.d., 5 ?m) utilizing a mobile phase of ammonium acetate buffer (pH 6.8) and acetonitrile (85:15 v/v) with UV detection at wavelength 252 nm at the flow rate 0 .8 ml/min. The proposed method was validated for sensitivity, selectivity, linearity, accuracy, precision, ruggedness, robustness and solution stability. The response of the drug was linear in the concentration range of 10-70 ?g/ml. Limit of detection and Limit of quantification was found to be 0.3 ?g/ml and 0.6 ?g/ml respectively. The % recovery ranged within 97-102 %. Method, system, interday and intraday precision was found to be within the limits of acceptance criteria. Method was found to be rugged when analysis was carried out by different analyst. The method was found to be sensitive and efficient with 2216 theoretical plates, 0.1128 mm HETP and tailing factor 1. The method was suitable for the quality control of cefotaxime in injection formulations. PMID:25206249

Lalitha, N; Pai, PN Sanjay

2009-01-01

38

Simultaneous RP-HPLC Estimation of Cefpodoxime Proxetil and Clavulanic Acid in Tablets.  

PubMed

A new, simple, precise, rapid and accurate RP-HPLC method has been developed for the simultaneous estimation of cefpodoxime proxetil and clavulanic acid from pharmaceutical dosage forms. The method was carried out on a Zorbax Eclipse XDB 5 mu C 18 (150x4.6 mm) column with a mobile phase consisting of acetonitrile:50 mM potassium dihydrogen phosphate buffer (pH 3.0, 70:30 v/v) at a flow rate of 1.0 ml/min. Detection was carried out at 228 nm. Aspirin was used as an internal standard. The retention time of clavulanic acid, cefpodoxime proxetil and aspirin was 4.43, 6.44 and 5.6 min, respectively. The developed method was validated in terms of accuracy, precision, linearity, limit of detection, limit of quantification and solution stability. The proposed method can be used for the estimation of these drugs in combined dosage forms. PMID:20177474

Malathi, S; Dubey, R N; Venkatnarayanan, R

2009-01-01

39

Simultaneous RP-HPLC Estimation of Cefpodoxime Proxetil and Clavulanic Acid in Tablets  

PubMed Central

A new, simple, precise, rapid and accurate RP-HPLC method has been developed for the simultaneous estimation of cefpodoxime proxetil and clavulanic acid from pharmaceutical dosage forms. The method was carried out on a Zorbax Eclipse XDB 5 ? C 18 (150×4.6 mm) column with a mobile phase consisting of acetonitrile:50 mM potassium dihydrogen phosphate buffer (pH 3.0, 70:30 v/v) at a flow rate of 1.0 ml/min. Detection was carried out at 228 nm. Aspirin was used as an internal standard. The retention time of clavulanic acid, cefpodoxime proxetil and aspirin was 4.43, 6.44 and 5.6 min, respectively. The developed method was validated in terms of accuracy, precision, linearity, limit of detection, limit of quantification and solution stability. The proposed method can be used for the estimation of these drugs in combined dosage forms. PMID:20177474

Malathi, S.; Dubey, R. N.; Venkatnarayanan, R.

2009-01-01

40

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

PubMed

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

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

2007-07-01

41

Determination and method validation of metamitron in soil by RP-HPLC.  

PubMed

A simple, rapid and economical method was developed and validated for the determination of metamitron using UV detector with RP-HPLC. Study of metamitron in soil was carried out. The compound was extracted from soil by methanol and clean-up was done on C-18 SPE column. Recovery ranged from 90.75 % to 94.05 % within 0.1-2.0 ?g g(-1) and RSD 1.80 %. Retention time was 3.8 min and limit of detection and limit of quantification were 0.001 and 0.008 ?g g(-1). The results indicated that the reported method could meet the requirement for the analysis of metamitron in trace amounts. PMID:24240634

Kumar, Satyendra; Tandon, Shishir; Sand, N K

2014-02-01

42

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

PubMed

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

Sakpakdeejaroen, Intouch; Juckmeta, Thana; Itharat, Arunporn

2014-08-01

43

Concurrent Estimation of Clopidogrel Bisulfate and Aspirin in Tablets by Validated RP-HPLC Method.  

PubMed

A simple, rapid, precise RP-HPLC method was developed for simultaneous estimation of aspirin and clopidogrel bisulphate in tablet dosage form used in the treatment of cardiovascular diseases. To achieve the maximum resolution, acetonitrile:50 mM potassium dihydrogen phosphate buffer:methanol, solution pH adjusted to 3, in the ratio 50:30:20; v/v was selected as mobile phase. This mixture was found to be appropriate allowing good separation of both the components at a flow rate of 1.5 ml/min and detection wavelength 240 nm. In these conditions clopidogrel bisulfate and aspirin were eluated at the 7.47 and 2.2 min. The linearity was found in the concentration range 1.5-7.5 and 3.5-15.0 ?g/ml, respectively. All the analytical validation parameters were determined and found with in the limit as per ICH guideline, which indicates the validity of method. PMID:21394272

Shrivastava, P K; Basniwal, P K; Jain, Deepti; Shrivastava, S K

2008-09-01

44

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

PubMed Central

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

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

2014-01-01

45

Development and validation of a RP-HPLC method for the determination of zidovudine and its related substances in sustained-release tablets.  

PubMed

A reversed-phase high-performance liquid chromatography (RP-HPLC) method for the rapid and accurate quantification of zidovudine (AZT) in sustained release tablets during stability testing was developed. A Waters RP-18 XTerra™(®) column, using a water:methanol (80:20, v/v%) mobile phase at a flow rate of 1.0 ml min(-1), and UV detection at 266 nm, was employed. The method of validation parameters indicate a linear range of between 40.0 to 220.0 µg ml(-1) with an LOQ of 1.985 µg ml(-1) and an LOD of 0.655 µg ml(-1) for the analyte. The degradation products of AZT were isolated and characterized for the first time. There was a very little decline of antiviral by heat, and AZT did not completely degrade either by acid or alkaline hydrolysis. On the other hand, oxidation caused a higher degradation stress in the drug. Finally, the degradation products resulting from stress studies were not found to interfere with the detection of antiviral, which is an advantage of the presently proposed method. PMID:21415511

dos Santos, Jucimary V; de Carvalho, Luís A E Batista; Pina, M Eugénia

2011-01-01

46

Rapid simultaneous determination of marmelosin, umbelliferone and scopoletin from Aegle marmelos fruit by RP-HPLC.  

PubMed

The surge of interest in naturally occurring phytochemicals with high therapeutic potential has led to the discovery of many molecules, out of which naturally occuring coumarins such as marmelosin, umbelliferone and scopoletin present in Aegle marmelos (Bael) fruit shows good therapeutic potential. The aim of the present work is to develop and validate Reverse Phase-High Performance Liquid Chromatography (RP-HPLC) method for simultaneous determination of marmelosin, umbelliferone and scopoletin in A. marmelos fruit extracts. The chromatographic separation was performed with isocratic elution of 55:45 (%, v/v) methanol-water containing 0.1 % acetic acid as mobile phase. The method used to analyse the extract of A. marmelos showed good resolution with retention time within 12 min. The relative concentrations of above phytoconstituent were determined in A. marmelos fruits. The method was found to give compact peaks for scopoletin, umbelliferone and marmelosin (Rt of 4.6, 6.5 and 11.3 min respectively) and were linear over the range 5-30 ?g ml(-1) (R(2)?=?0.9655), 2-10 ?g ml(-1) (R(2)?=?0.9964) and 2-10 ?g ml(-1) (R(2)?=?0.9862) respectively. The mean recoveries for marmelosin, umbelliferone and scopoletin at three concentrations were in the range of 98.8-102.9, 98.8-101.1 and 94.2-98.3 % respectively. The relative standard deviation of accuracy, precision and repeatability were within 2 %, indicating the method produced highly reproducible results. Therefore this simple, precise and accurate method enables simultaneous separation of this phytoconstituent and hence can be successfully applied in analysis and routine quality control of herbal material and formulation containing A. marmelos. PMID:25190892

Shinde, P B; Katekhaye, S D; Mulik, M B; Laddha, K S

2014-09-01

47

Separation and quantification of water buffalo milk protein fractions and genetic variants by RP-HPLC.  

PubMed

A RP-HPLC method, developed for the separation and quantification of the most common genetic variants of bovine milk proteins, was successfully applied to the analysis of water buffalo milk. All the most common buffalo casein and whey proteins fractions, as well as their genetic variants, were detected and separated simultaneously in 40 min. Purified buffalo proteins were used as calibration standards and a total of 536 individual milk samples were analysed for protein composition. ?(S1)-, ?(S2)-, ??-, and ?-casein were 32.2%, 15.8%, 36.5%, and 15.5%, respectively, of total casein content, whereas content of ?-Lactoglobulin was approximately 1.3 times as high as that of ?-Lactalbumin. The existence of a polymorphism of ?-casein was demonstrated in Mediterranean water buffalo and ?(S1)- and ?-casein genetic variants were successfully detected by RP-HPLC. PMID:23122071

Bonfatti, Valentina; Giantin, Mery; Rostellato, Roberta; Dacasto, Mauro; Carnier, Paolo

2013-01-15

48

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

PubMed

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

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

2014-01-01

49

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

A rapid and stability-indicating reversed phase high-performance liquid chromatography (RP-HPLC) method was developed for simultaneous quantification of paracetamol and ibuprofen in their combined dosage form especially to get some more advantages over other methods already developed for this combination. The method was validated according to United States Pharmacopeia (USP) guideline with respect to accuracy, precision, specificity, linearity, solution stability, robustness, sensitivity, and system suitability. Forced degradation study was validated according to International Conference on Harmonisation (ICH). For this, an isocratic condition of mobile phase comprising phosphate buffer (pH 6.8) and acetonitrile in a ratio of 65:35, v/v at a flow rate of 0.7 mL/minute over RP C18 (octadecylsilane (ODS), 150 × 4.6 mm, 5 ?m, Phenomenex Inc.) column at ambient temperature was maintained. The method showed excellent linear response with correlation coefficient (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

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

2014-01-01

50

Determination of methylparaben, propylparaben, clotrimazole and its degradation products in topical cream by RP-HPLC  

Microsoft Academic Search

Summary  Reversed-phase, high-performance liquid chromatographic (RP-HPLC) methods with UV detection were developed and validated for\\u000a determination of compounds in a topical cream. The first method describes determination of the active component clotrimazole\\u000a and two preservatives present in the cream; methylparaben and propylparaben. The second method describes determination of\\u000a two degradation products of clotrimazole, imidazole and (2-chlorophenyl) diphenylmethanol, in a topical cream

P. Solich; R. Hájková; M. Pospíšilová; J. Šícha

2002-01-01

51

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

PubMed

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

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

2011-09-01

52

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

Microsoft Academic Search

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

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

53

Chemical fingerprinting of Isatis indigotica root by RP-HPLC and hierarchical clustering analysis  

Microsoft Academic Search

The aim was to establish a method for extraction and chemical fingerprinting of extracts of Isatis indigotica roots (“Ban–Lan–Gen”) and to apply the method developed to 18 Ban–Lan–Gen samples. RP-HPLC with gradient elution was performed on authentic reference standards of powdered I. indigotica roots, indigotin and indirubin purchased from the National Institute for the Control of Pharmaceutical and Biological Products

P. Zou; Y. Hong; H. L. Koh

2005-01-01

54

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

PubMed

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

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

2014-01-01

55

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

PubMed

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

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

2014-01-01

56

RP-HPLC method development and validation for simultaneous estimation of atorvastatin calcium and pioglitazone hydrochloride in pharmaceutical dosage form.  

PubMed

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

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

2014-10-01

57

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

PubMed

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

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

2014-01-01

58

RP-HPLC prefractionation and its application in expressional proteomics analysis of an in vitro viral infection model.  

PubMed

Prefractionation of complex protein mixtures is an efficient method for increasing the separation power of 2-DE. RP-HPLC has been successfully utilized as a prefractionation method prior to 2-DE. Here we describe the optimization of an efficient RP-HPLC method for prefractionation of baby hamster kidney cell solubilized proteins. A step gradient elution of acetonitrile was optimized and collected fractions were further examined by SDS-PAGE and 2-DE. By utilizing this method an effective increase in separation power of 2-DE is accomplished. Moreover, we describe the application of this method to expressional proteome analysis of a virally infected cell model. PMID:17120811

Vaziri, Behrouz; Rahimpour, Mehdi; Eslami, Naser; Fayaz, Ahmad; Rahimian, Heshmat

2006-10-01

59

Determination of some phenolic compounds in red wine by RP-HPLC: method development and validation.  

PubMed

A methodology employing reversed-phase high-performance liquid chromatography (RP-HPLC) was developed and validated for simultaneous determination of five phenolic compounds in red wine. The chromatographic separation was carried out in a C(18) column with water acidify with acetic acid (pH 2.6) (solvent A) and 20% solvent A and 80% acetonitrile (solvent B) as the mobile phase. The validation parameters included: selectivity, linearity, range, limits of detection and quantitation, precision and accuracy, using an internal standard. All calibration curves were linear (R(2) > 0.999) within the range, and good precision (RSD < 2.6%) and recovery (80-120%) was obtained for all compounds. This method was applied to quantify phenolics in red wine samples from Santa Catarina State, Brazil, and good separation peaks for phenolic compounds in these wines were observed. PMID:21859541

Burin, Vívian Maria; Arcari, Stefany Grützmann; Costa, Léa Luzia Freitas; Bordignon-Luiz, Marilde T

2011-09-01

60

Relationship between vasorelaxation of flavonoids and their retention index in RP-HPLC.  

PubMed

In the present study the relationship between the vasodilation of flavonoids and their retention index (RI) was investigated. Retention index (RI) values of 18 flavonoids, including flavones, flavonols, flavanones, flavanols and isoflavones were measured by an RP-HPLC method based on alkan-2-ones. Vasorelaxation of the flavonoids was measured by measuring the reduction in tension by flavonoids in rat thoracic aorta precontracted by phenylephrine (PE, 10(-6) mol/L). The results demonstrated that the potency of the vasorelaxation of flavonoids was positive by correlated with RI. The regression equation was Rex 11.68 + 0.11 RI (n = 18, r = 0.915, P < 0.01). PMID:16964706

Wu, Haohao; Jiang, Huidi; Wang, Lingfei; Hu, Yongzhou

2006-08-01

61

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

PubMed

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

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

2013-09-01

62

A novel RP-HPLC method for the determination of bharangin in Ghantu bharangi crude extracts.  

PubMed

An accurate, simple, reproducible and sensitive RP-HPLC method for the determination of bharangin has been developed and validated. The separation of bharangin and 2-nitroaniline (internal standard) was achieved on Supelcosil LC-18 (3micro, 150 x 4.6 mm i.d.) column using UV detection at 388 nm. The mobile phase was consisting of methanol and 0.01 M KH(2)PO(4) buffer (pH 3.0, adjusted with ortho-phosphoric acid) (75:25, % v/v). The linear range of detection for bharangin was found to be 10-50 ng/ml. Intra-and inter-days assay relative standard deviations were less than 3.21. The method has been successfully applied to the determination of bharangin in various crude extracts. The method has been shown to be linear, reproducible, specific, and rugged. PMID:19168424

Sathish, Thadikamala; Brahmaiah, Pendyala; Sathya, Kancherla; Bhojaraju, Pullasi; Naik, Nenavath Gopal; Kezia, Devarapalli; Prakasam, Reddy Shetty

2009-01-01

63

Chemical fingerprinting of Isatis indigotica root by RP-HPLC and hierarchical clustering analysis.  

PubMed

The aim was to establish a method for extraction and chemical fingerprinting of extracts of Isatis indigotica roots ("Ban-Lan-Gen") and to apply the method developed to 18 Ban-Lan-Gen samples. RP-HPLC with gradient elution was performed on authentic reference standards of powdered I. indigotica roots, indigotin and indirubin purchased from the National Institute for the Control of Pharmaceutical and Biological Products (NICPBP) of China. Eighteen "Ban-Lan-Gen" samples (including the reference powdered herb) were bought from Singapore and different regions in China. Comparisons of the chromatograms showed that the samples can be divided into three groups. The chromatograms of the extracts of five samples were found to be similar to that of the extract of the authentic sample. Eight other samples had similar peaks as the authentic sample but the intensities of the peaks were generally lower, except for the peaks between retention times of 10-40 min. Peaks in these regions were more intense than those found in the extract of the authentic sample. Forty-five characteristic peaks could be found in the extracts of all the above samples. Peaks at retention times 52 and 53 min were determined to be indigotin and indirubin, respectively. The remaining four samples had similar chemical fingerprints to each other but were different from that of the authentic sample. Hierarchical clustering analysis gave similar results as the visual comparison. The RP-HPLC method developed allows simple identification and comparisons of I. indigotica roots. This is the first report of hierarchical clustering analysis of I. indigotica root. PMID:15925253

Zou, P; Hong, Y; Koh, H L

2005-07-01

64

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

PubMed Central

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

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

2011-01-01

65

Development and validation of RP-HPLC method for the analysis of metformin.  

PubMed

The reversed-phase high-performance liquid chromatographic (RP-HPLC) method has been developed to quantify metformin hydrochloride (MfCl) in raw material and pharmaceutical formulations using C(18) analytical reverse-phase column. Diazepam was used as an internal standard. Mobile phase consisted of methanol-water (30:70 v/v), pumped at a flow rate of 0.5 ml/min at ambient temperature and the retention time was about 4.4 min with symmetrical peaks. (MfCl) was detected by ultraviolet absorbance at 233 nm with no interference of commonly used excipients. The method was linear over the concentration range 0.312-5 mug/mL (R2 = 0.9995). The limit of detection of metformin was 0.1 mug/mL and the limit of quantitation was 0.3 mug/mL. The results obtained showed a good agreement with the declared contents in case of pharmaceutical formulations. The proposed method is rapid, accurate, economical and selective and it may be used for the quantitative analysis of metformin in Neodipar tablets because of its sensitivity and reproducibility. PMID:16935831

Arayne, M Saeed; Sultana, Najma; Zuberi, M Hashim

2006-07-01

66

Role of Organic Modifier and Gradient Shape in RP-HPLC Separation: Analysis of GCSF Variants.  

PubMed

Reversed-phase high-performance liquid chromatography (RP-HPLC) of therapeutic proteins continues to play a significant role in product characterization. This study focuses on two key aspects of HPLC method development, namely the selection of organic modifier and the gradient shape. Separation of granulocyte colony-stimulating factor variants is being used as a case study to illustrate these concepts. The results demonstrate that careful selection of a binary or ternary mixture of solvents with water is an important factor to be considered for achieving the desired resolution of closely related impurities. The resolution of different types of impurities has been shown to be selective toward the choice of eluent along with the ratio in which they are mixed. In addition, this study also presents a systematic approach for selection of gradient shape based on center point solvent composition, initial solvent composition and the steepness of the gradient. The approach proposed in this study was successfully used to reduce the time of analysis from 70 min for the pertinent European Pharmacopeia method to 15 min by using a solvent system with two organic modifiers (acetonitrile and methanol) along with a sigmoidal-shaped gradient. PMID:25637134

Joshi, Varsha S; Kumar, Vijesh; Rathore, Anurag S

2015-03-01

67

RP-HPLC determination of water-soluble vitamins in honey.  

PubMed

The assessment and validation of reliable analytical methods for the determination of vitamins in sugar-based matrices (e.g. honey) are still scarcely explored fields of research. This study proposes and fully validates a simple and fast RP-HPLC method for the simultaneous determination of five water-soluble vitamins (vitamin B(2), riboflavin; vitamin B(3), nicotinic acid; vitamin B(5), pantothenic acid; vitamin B(9), folic acid; and vitamin C, ascorbic acid) in honey. The method provides low detection and quantification limits, very good linearity in a large concentration interval, very good precision, and the absence of any bias. It has been successfully applied to 28 honey samples (mainly from Sardinia, Italy) of 12 different botanical origins. While the overall amount of the analytes in the samples is quite low (always below 40 mg kg(-1)), we have observed a marked dependence of some of their concentrations (i.e. vitamin B(3) and vitamin B(5)) and the botanical origin of the honey. This insight might lead to important characterization features for this food item. PMID:21147338

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

2011-01-15

68

Development and Validation of New RP-HPLC Method for the Determination of Dexrazoxane  

PubMed Central

A new sensitive, precise, rapid and linear RP-HPLC method was developed and validated for the determination of dexrazoxane in formulations and human serum samples. Good chromatographic separation of dexrazoxane was achieved by using Kromasil C18 column. The system was operated at ambient temperature using a mobile phase consisting of methanol, 5% ortho phosphoric acid, 0.01M ammonium dihydrogen phosphate and tetrahydrofuran, pH 4.2 (10:40:30:20, v/v) isocratically at a flow rate of 1 ml/min. The method showed high sensitivity with good linearity (r2=0.9998) over the tested concentration range of 0.1 to 0.9 mg/ml. Detection was carried out at 272 nm and retention time was 7.005 min. The accuracy, formulation assay and percentage of RSD were 100.03, 97.48 and 0.03184, respectively with tailing factor (1.84). This method can be used for the routine quality control analysis. PMID:23798789

Basaveswara Rao, M. V.; Prasanthi, V.; Rao, G. Venkata; Raman, B. V.

2012-01-01

69

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

PubMed

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

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

2014-01-01

70

Drug Dissolution Studies and Determination of Deflazacort in Pharmaceutical Formulations and Human Serum Samples by RP?HPLC  

Microsoft Academic Search

A simple, sensitive, reproducible, and validated RP?HPLC method with UV detection is described for the determination of deflazacort in raw material, pharmaceuticals, human serum samples, and in?vitro drug dissolution studies. The separation was achieved using a C18 (250 × 4.6 mm; 5 µm) column and a mobile phase comprising acetonitrile, methanol, and 0.067 M KH2PO4 in the ratio (27:20:53, v\\/v\\/v), adjusted to pH 6.5 with

Yalç?n Özkan; Ayhan Sava?er; Çetin Ta?; Bengi Uslu; Sibel A. Özkan

2003-01-01

71

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

PubMed

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

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

2014-02-01

72

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

PubMed Central

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 ?m 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 ?g/ml with r2=0.9995. The limit of detection and quantification were found to be 3.144 and 9.52 ?g/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

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

2013-01-01

73

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

PubMed

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 ?m 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 ?g/ml with r(2)=0.9995. The limit of detection and quantification were found to be 3.144 and 9.52 ?g/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

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

2013-11-01

74

RP-HPLC method for simultaneous estimation of bisoprolol fumarate and hydrochlorothiazide in tablet formulation  

Microsoft Academic Search

A simple, precise and stability-indicating HPLC method was developed and validated for the simultaneous determination of bisoprolol fumarate and hydrochlorothiazide in pharmaceutical dosage form. The method involves the use of easily available inexpensive laboratory reagents. The separation was achieved on an Inertsil ODS 3V (25cm×4.6mm) 5?m column with isocratic flow. The mobile phase at a flow rate of 1.0mLmin?1, consisted

Sneha J. Joshi; Pradnya A. Karbhari; Suvarna I. Bhoir; K. S. Bindu; Chhanda Das

2010-01-01

75

Development and validation of a novel stability-indicating HPLC method for the simultaneous assay of betamethasone-17-valerate, fusidic acid, potassium sorbate, methylparaben and propylparaben in a topical cream preparation.  

PubMed

A novel stability-indicating reversed phase high performance liquid chromatographic (RP-HPLC) method for the simultaneous assay of betamethasone-17-valerate, fusidic acid and potassium sorbate as well as methyl- and propylparaben in a topical cream preparation has been developed. A 100mm×3.0mm ID. Ascentis Express C18 column maintained at 30°C and UV detection at 240nm were used. A gradient programme was employed at a flow-rate of 0.75ml/min. Mobile phase A comprised of an 83:17 (v/v) mixture of acetonitrile and methanol and mobile phase B of a 10g/l solution of 85% phosphoric acid in purified water. The method has been validated according to current International Conference on Harmonisation (ICH) guidelines and applied during formulation development and stability studies. The procedure has been shown to be stability-indicating for the topical cream. PMID:24731970

Byrne, Jonathan; Velasco-Torrijos, Trinidad; Reinhardt, Robert

2014-08-01

76

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

PubMed Central

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 ?g/ml for cefixime and 6-36 ?g/ml for linezolid. For RP-HPLC, the separation was achieved by Phenomenex Luna C18 (250×4.6 mm) 5 ?m 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

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

2014-01-01

77

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

PubMed

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 ?g/ml for cefixime and 6-36 ?g/ml for linezolid. For RP-HPLC, the separation was achieved by Phenomenex Luna C18 (250×4.6 mm) 5 ?m 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

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

2014-01-01

78

RP-HPLC method for simultaneous estimation of bisoprolol fumarate and hydrochlorothiazide in tablet formulation.  

PubMed

A simple, precise and stability-indicating HPLC method was developed and validated for the simultaneous determination of bisoprolol fumarate and hydrochlorothiazide in pharmaceutical dosage form. The method involves the use of easily available inexpensive laboratory reagents. The separation was achieved on an Inertsil ODS 3V (25cmx4.6mm) 5microm column with isocratic flow. The mobile phase at a flow rate of 1.0mLmin(-1), consisted of 0.1M potassium dihydrogen phosphate buffer and acetonitrile (70:30, v/v). The UV detection was carried out at 228nm. A linear response was observed over the concentration range 2.5-50microgmL(-1) of bisoprolol fumarate and the concentration range 6.25-125microgmL(-1) of hydrochlorothiazide. Limit of detection and limit of quantitation for bisoprolol fumarate were 0.01 and 0.03microgmL(-1), respectively and for hydrochlorothiazide were 0.01 and 0.05microgmL(-1), respectively. The method was successfully validated in accordance to ICH guidelines acceptance criteria for specificity, linearity, accuracy, precision, robustness, ruggedness and system suitability. Individual drugs (bisoprolol fumarate and hydrochlorothiazide), their combinations and the tablets 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 peaks in the stressed samples was confirmed by photodiode array detector. The method was used for accelerated stability study on marketed and in-house formulations. The analysis concluded that the method was selective for simultaneous estimation of bisoprolol fumarate and hydrochlorothiazide and was stability-indicating. PMID:19926421

Joshi, Sneha J; Karbhari, Pradnya A; Bhoir, Suvarna I; Bindu, K S; Das, Chhanda

2010-07-01

79

A validated RP-HPLC-UV method for quantitative determination of puerarin in Pueraria tuberosa DC tuber extract  

PubMed Central

Background: Pueraria tuberosa (Fabaceae) is a well-known medicinal herbs used in Indian traditional medicines. The puerarin is one of the most important bioactive constituent found in the tubers of this plant. Quantitative estimation of bioactive molecules is essential for the purpose of quality control and dose determination of herbal medicines. The study was designed to develop a validated reversed phase high-performance liquid chromatography (RP-HPLC) method for the quantification of puerarin in the tuber extract of P. tuberosa. Materials and Methods: The RP-HPLC system with Luna C18 (2) 100 Å, 250 × 4.6 mm column was used in this study. The analysis was performed using the mobile phase: 0.1% acetic acid in acetonitrile and 0.1% acetic acid in water (90:10, v/v) under column temperature 25°C. The detection wavelength was set at 254 nm with a flow rate of 1 ml/min. The method validation was performed according to the guidelines of International Conference on Harmonization. Results: The puerarin content of P. tuberosa extract was found to be 9.28 ±0.09%. The calibration curve showed good linearity relationship in the range of 200-1000?g/ml (r2>0.99). The LOD and LOQ were 57.12 and 181.26?g/ml, respectively and the average recovery of puerarin was 99.73% ±1.02%. The evaluation of system suitability, precision, robustness and ruggedness parameters were also found to produce satisfactory results. Conclusions: The developed method is very simple and rapid with excellent specificity, accuracy and precision which can be useful for the routine analysis and quantitative estimation of puerarin in plant extracts and formulations. PMID:23781483

Maji, Amal K.; Maity, Niladri; Banerji, Pratim; Banerjee, Debdulal

2012-01-01

80

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

PubMed Central

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

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

2013-01-01

81

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

PubMed

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

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

2011-12-01

82

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

PubMed

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

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

2013-09-01

83

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

PubMed

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

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

2014-07-01

84

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

PubMed

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 (?max of AMLO), 270.2 nm (?max of HCTZ) and 249.2 nm (?max 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

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

2014-01-01

85

Simultaneous determination of piracetam and its four impurities by RP-HPLC with UV detection.  

PubMed

A simple and rapid high-performance liquid chromatographic method for the separation and determination of piracetam and its four impurities, 2-oxopyrrolidin-1-yl)acetic acid, pyrrolidin-2-one, methyl (2-oxopyrrolidin-1-yl)acetate, and ethyl (2-oxopyrrolidin-1-yl)acetate, was developed. The separation was achieved on a reversed-phase C(18) Nucleosil column (25 cm x 0.46 cm, 10 microm). The mobile phase is composed of an aqueous solution containing 0.2 g/L of triethyl amine-acetonitrile (85:15, v/v). The pH of the mobile phase was adjusted to 6.5 with phosphoric acid at a flow rate of 1 mL/min at ambient temperature and UV detection at 205 nm. The developed method was found to give good separation between the pure drug and its four related substance. The polynomial regression data for the calibration plots showed good linear relationship in the concentration range of 50-10,000 ng/mL, 25-10,000 ng/mL, 45-10,000 ng/mL, 34-10,000 ng/mL, and 55-10,000 ng/mL, respectively, with r(2) = 0.9999. The method was validated for precision, accuracy, ruggedness, and recovery. The minimum quantifiable amounts were found to be 50 ng/mL of piracetam, 25 ng/mL of 2-oxopyrrolidin-1-yl)acetic acid, 45 ng/mL of pyrrolidin-2-one, 34 ng/mL of methyl (2-oxopyrrolidin-1-yl)acetate, and 55 ng/mL of ethyl (2-oxopyrrolidin-1-yl)acetate. Statistical analysis proves that the method is reproducible and selective for the estimation of piracetam as well as its related substance. As the method could effectively separate the drug from the related substances, it can be employed as a stability-indicating one. The proposed method shows high efficiency, allowing the separation of the main component piracetam from other impurities. PMID:20819285

Arayne, M Saeed; Sultana, Najma; Siddiqui, Farhan Ahmed; Mirza, Agha Zeeshan; Qureshi, Faiza; Zuberi, M Hashim

2010-08-01

86

A validated RP-HPLC method to investigate finasteride in human skin after in vitro topically applying vesicular nanocarrier.  

PubMed

The pharmacotherapeutic efficiency of topical drug delivery systems is mainly dominated by the skin distribution of therapeutic agents. In this work, a sensitive, rapid and fully-validated reversed-phase high performance liquid chromatography (RP-HPLC) method was developed to determine finasteride in human cadaver skin after different vesicular formulations were applied. Drug in different depth of skin layers were measured with an EclipseXDB-C18 column. The mobile phase consisted of 75% (v/v) methanol containing 0.2% phosphoric acid buffered to pH 3.0 with triethylamine under isocratic conditions. The system was operated at 40°C and the mobile phase flow rate was set at 1 mL/min. The standard-calibration curve was linear within range of 5 to 200 ng/ml with correlation coefficient 0.9996. The intra-assay precision was less than 3.9% while the inter-assay precision was less than 7.1% with the bias range of -8.6 to 4.1%. This method was found to be specific, accurate, and sensitive and was successfully used to determine the accumulation of finasteride after in-vitro percutaneous delivery by liposomal or ethosomal drug delivery nanocarriers. PMID:24811812

Zheng, Feiyue; Rao, Yuefeng; Lou, Yan; Lu, Xiaoyang

2014-05-01

87

RP-HPLC analysis of the phenolic compounds of plant extracts. investigation of their antioxidant capacity and antimicrobial activity.  

PubMed

Extracts of aromatic plants of Greek origin were examined as potential sources of phenolic compounds. RP-HPLC with UV detection was employed for the identification and quantification of the phenolic antioxidants, present in methanolic extracts. The most abundant phenolic acids were ferulic acid (1.1-280 mg/100 g of dry sample) and caffeic acid (1.2-60 mg/100 g of dry sample). (+)-Catechin and quercetin were the most abundant flavonoids. Apigenin and luteolin were detected in high amounts in Menta pulegium and Thymus vulgaris, respectively. The antioxidant capacity was determined, in dried ground plants and in their methanol extracts, with the Rancimat test using sunflower oil as substrate. Both pulverized plants and extracts showed antioxidant capacity. Total phenolic content in the extracts was determined spectrometrically according to the Folin-Ciocalteu assay and ranged from 1 to 21 mg of gallic acid/100 g of dry sample. Antimicrobial activity of the extracts against selected microbes was also conducted in this study. PMID:15713039

Proestos, C; Chorianopoulos, N; Nychas, G-J E; Komaitis, M

2005-02-23

88

Development and validation of RP-HPLC method for sildenafil citrate in rat plasma-application to pharmacokinetic studies  

PubMed Central

Sildenafil citrate (SIL) is used in the treatment of erectile dysfunction and other chronic disorders. For the pharmacokinetic investigation of SIL we developed a simple and sensitive method for the estimation of SIL in rat plasma by reverse phase high-performance liquid chromatography (RP-HPLC). The drug samples were extracted by liquid–liquid extraction with 300 ?l of acetonitrile and 5 ml of diethyl ether. Chromatographic separation was achieved on C18 column using methanol:water (85:15 v/v) as mobile phase at a flow rate of 1 ml/min and UV detection at 230 nm. The retention time of SIL was found to be 4.0 min having a separation time less than 5 min. The developed method was validated for accuracy, precision, linearity and recovery. Linearity studies were found to be acceptable over the range of 0.1–6 ?g/ml. The method was successfully applied for the analysis of rat plasma sample for the application in pharmacokinetic study, drug interaction, bioavailability and bioequivalence. PMID:23960848

Tripathi, A.S.; Sheikh, I.; Dewani, A.P.; Shelke, P.G.; Bakal, R.L.; Chandewar, A.V.; Mazumder, P.M.

2012-01-01

89

Development and Validation of an RP-HPLC Method for CB13 Evaluation in Several PLGA Nanoparticle Systems  

PubMed Central

A simple, fast, and reversed-phase high-performance liquid chromatographic (RP-HPLC) method has been developed and validated for determining of a cannabinoid derivate, which displays potent antihyperalgesic activity, 1-naphthalenyl[4-(pentyloxy)-1-naphthalenyl]methanone (CB13) into PLGA nanoparticles. Separation was achieved in a C18 column using a mobile phase consisting of two solvents: solvent A, consisting of acetonitrile?:?water?:?acetic acid (75?:?23.7?:?1.3?v/v), and solvent B, consisting of acetonitrile. An isocratic method (70?:?30?v/v), with a flow rate of 1.000?mL/min, and a diode array detector were used. The developed method was precise, accurate, and linear over the concentration range of analysis with a limit of detection and a limit of quantification of 0.5 and 1.25??g/mL, respectively. The developed method was applied to the analysis of CB13 in nanoparticles samples obtained by three different procedures (SEV, FF, and NPP) in terms of encapsulation efficiency and drug release. Nanoparticles size and size distribution were also evaluated founding that NPP method presented the most lowest particle sizes with narrow-size distribution (?320?nm) and slightly negative zeta potential (??25?mV) which presumes a suitable procedure for the synthesis of PLGA-CB13 nanoparticles for oral administration. PMID:22792051

Álvarez-Fuentes, J.; Martín-Banderas, L.; Muñoz-Rubio, I.; Holgado, M. A.; Fernández-Arévalo, M.

2012-01-01

90

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

PubMed Central

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

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

2011-01-01

91

Development and validation of RP-HPLC method for sildenafil citrate in rat plasma-application to pharmacokinetic studies.  

PubMed

Sildenafil citrate (SIL) is used in the treatment of erectile dysfunction and other chronic disorders. For the pharmacokinetic investigation of SIL we developed a simple and sensitive method for the estimation of SIL in rat plasma by reverse phase high-performance liquid chromatography (RP-HPLC). The drug samples were extracted by liquid-liquid extraction with 300 ?l of acetonitrile and 5 ml of diethyl ether. Chromatographic separation was achieved on C18 column using methanol:water (85:15 v/v) as mobile phase at a flow rate of 1 ml/min and UV detection at 230 nm. The retention time of SIL was found to be 4.0 min having a separation time less than 5 min. The developed method was validated for accuracy, precision, linearity and recovery. Linearity studies were found to be acceptable over the range of 0.1-6 ?g/ml. The method was successfully applied for the analysis of rat plasma sample for the application in pharmacokinetic study, drug interaction, bioavailability and bioequivalence. PMID:23960848

Tripathi, A S; Sheikh, I; Dewani, A P; Shelke, P G; Bakal, R L; Chandewar, A V; Mazumder, P M

2013-07-01

92

Chemometrically assissted optimization and validation of RP-HPLC method for the analysis of itraconazole and its impurities.  

PubMed

This paper presents the chemometrically assisted optimization and validation of the RP-HPLC method intended for the quantitative analysis of itraconazole and its impurities in pharmaceutical dosage forms. To reach the desired chromatographic resolution with a limited number of experiments in a minimum amount of time, Box- -Behnken design was used to simultaneously optimize some important chromatographic parameters, such as the acetonitrile content in the mobile phase, pH of the aqueous phase and the column temperature. Separation between itraconazole and impurity F was identified as critical and selected as a response during the optimization. The set optimal mobile phase composition was acetonitrile/ water pH 2.5 adjusted with o-phosphoric acid (50:50, V/V). Separations were performed on a Zorbax Eclipse XDB-C18, 4.6 × 150 mm, 5 ?m particle size column with the flow rate 1 mL min-1, column temperature set at 30 °C and UV detection at 256 nm. The established method was then subjected to method validation and the required validation parameters were tested. For the robustness evaluation, fractional factorial 24-1 design was utilized and factors that might significantly affect the system performance were defined. As other validation parameters were also found to be suitable, the possibility to apply the proposed method for the determination of itraconazole, its impurities B and F in any laboratory under different circumstances has been proven. PMID:23846140

Kasagi?, Irena; Malenovi?, An?elija; Jovanovi?, Marko; Raki?, Tijana; Jan?i? Stojanovi?, Biljana; Ivanovi?, Darko

2013-06-01

93

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

PubMed

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

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

2008-06-01

94

Isolation and determination of alpha-dicarbonyl compounds by RP-HPLC-DAD in green and roasted coffee.  

PubMed

Glyoxal, methylglyoxal, and diacetyl formed as Maillard reaction products in heat-treated food were determined in coffee extracts (coffee brews) obtained from green beans and beans with different degrees of roast. The compounds have been reported to be mutagenic in vitro and genotoxic in experimental animals in a number of papers. More recently, alpha-dicarbonyl compounds have been implicated in the glycation process. Our data show that small amounts of glyoxal and methylglyoxal occur naturally in green coffee beans. Their concentrations increase in the early phases of the roasting process and then decline. Conversely, diacetyl is not found in green beans and forms later in the roasting process. Therefore, light and medium roasted coffees had the highest glyoxal and methylglyoxal content, whereas dark roasted coffee contained smaller amounts of glyoxal, methylglyoxal, and diacetyl. For the determination of coffee alpha-dicarbonyl compounds, a reversed-phase high performance liquid chromatography with a diode array detector (RP-HPLC-DAD) method was devised that involved the elimination of interfering compounds, such as chlorogenic acids, by solid phase extraction (SPE) and their derivatization with 1,2-diaminobenzene to give quinoxaline derivatives. Checks of SPE and derivatization conditions to verify recovery and yield, respectively, resulted in rates of 100%. The results of the validation procedure showed that the proposed method is selective, precise, accurate, and sensitive. PMID:17927199

Daglia, Maria; Papetti, Adele; Aceti, Camilla; Sordelli, Barbara; Spini, Valentina; Gazzani, Gabriella

2007-10-31

95

Studies on log Po/w of quinoxaline di-N-oxides: a comparison of RP-HPLC experimental and predictive approaches.  

PubMed

As reported in our previous papers, a series of quinoxaline-2-carboxamide 1,4-di-N-oxide derivatives were synthesized and studied as anti-tuberculosis agents. Here, the capability of the shake-flask method was studied and the retention time (expressed as log K) of 20 compounds were determined by RP-HPLC analysis. We found that the prediction of log P by the RP-HPLC analysis can result in a high accuracy and can replace the shake-flask method avoiding the experimental problems presented by quinoxaline di-N-oxides. The studied compounds were subjected to the ALOGPS module with the aim of comparing experimental log P(o/w) values and predicted data. Moreover, a preliminary in silico screening of the QSAR relationship was made confirming the influence of reduction peak potential, lipophilicity, H-bond donor capacity and molecular dimension descriptors on anti-tuberculosis activity. PMID:22143549

Moreno, Elsa; Gabano, Elisabetta; Torres, Enrique; Platts, James A; Ravera, Mauro; Aldana, Ignacio; Monge, Antonio; Pérez-Silanes, Silvia

2011-01-01

96

Determination of Heavy Metal Ions in Chinese Herbal Medicine by Microwave Digestion and RP-HPLC with UV-Vis Detection  

Microsoft Academic Search

A new method for the simultaneous determination of heavy metal ions in Chinese herbal medicine by microwave digestion and reversed-phase high-performance liquid chromatography (RP-HPLC) has been developed. The Chinese herbal medicine samples were digested by microwave digestion. Lead, cadmium, mercury, nickel, copper, zinc, and tin ions in the digested samples were pre-column derivatized with tetra-(4-chlorophenyl)-porphyrin (T 4-CPP) to form the

Yaling Yang; Yan Guangyu; Qiang Lin

2004-01-01

97

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

Microsoft Academic Search

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

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

2003-01-01

98

Development and Validation of RP-HPLC Method for Simultaneous Determination of Granisetron and Dexamethasone  

PubMed Central

A new simple, selective, rapid, precise and accurate reverse phase HPLC method has been developed for simultaneous estimation of granisetron and dexamethasone. The method was developed using CPS Hypersil CN column (250×4.6 mm I.D.) with a mobile phase consisting of acetonitrile:buffer (100 mM Triethylamine adjusted to pH 3.0 with o-phosphoric acid) in ratio of 25:75 at a flow rate of 2 ml/min. Detection was carried out at 242 nm. The developed method was evaluated for various system suitability parameters and validated for linearity, accuracy, precision, LOD, LOQ as per ICH guidelines. It was also evaluated for bench top stability and freeze/thaw stability. The proposed method can be used for the estimation of these drugs in their combined dosage forms. PMID:23112409

Heda, A. A.; Kathiriya, J. M.; Gadade, D. D.; Puranik, P. K.

2011-01-01

99

Stability Indicators in Network Reconstruction  

PubMed Central

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 analysis on a second dataset (166 subjects) with good reproducibility. PMID:24587057

Riccadonna, Samantha; Jurman, Giuseppe; Furlanello, Cesare

2014-01-01

100

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

PubMed

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 (150×4.6mm; 5?m) column at ambient temperature and the total run time was less than 7min. A mixture of acetonitrile - 25mM phosphate buffer pH 3 (27:73, v/v) was used as the mobile phase at a flow rate of 1.0mL/min and the effluent monitored by measuring absorbance at 220nm. Calibration graphs were established in the range 20-70mg/L for chloramphenicol, 6-14mg/L for dexamethasone and 3-8mg/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

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

2015-03-15

101

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

PubMed Central

Many in vitro experiments aimed at studying 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, as well as 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 for the actual redox potential of the assayed sample, facilitates the direct correlation between biochemical findings and the experimental redox status. Reversed-Phase High Performance Liquid Chromatography (RP-HPLC) is a widely used, well-established tool for the analysis and purification of biomolecules, including proteins and peptides. Here, we describe a simple, robust, and quantitative RP-HPLC method we developed and tested to determine 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

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

2013-01-01

102

Development and Validation of a RP-HPLC Method for Determination of Cyclosporine in Capsule.  

PubMed

A simple, specific and accurate reverse phase high performance liquid chromatographic method was developed for the determination of cyclosporine in capsule dosage form. XTerra C18 column was used as stationary phase with mobile phase acetonitrile in combination with 0.1% trifluoro acetic acid buffer and pH is adjusted to 1.4. Method was developed in an isocratic run of 20% trifluoro acetic acid with 80% acetonitrile for 10 min, at flow rate of 1 ml/min. Effluents were monitored at 210 nm. Retention time of cyclosporine was 3.855 min. The method was validated for specificity, linearity, accuracy, precision, limit of quantification, limit of detection, robustness and solution stability. Limit of quantification and limit of detection of cyclosporine was found to be 100 ng/ml and 200 ng/ml. Recovery was found to be in the range of 98.08-101.55%. The proposed method was successfully applied for the quantitative determination of cyclosporine in a capsule dosage form. PMID:20838535

Aziz, F; Gupta, A; Khan, M F

2010-03-01

103

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

PubMed

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

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

2013-07-01

104

Development and Validation of a RP-HPLC Method for Determination of Cyclosporine in Capsule  

PubMed Central

A simple, specific and accurate reverse phase high performance liquid chromatographic method was developed for the determination of cyclosporine in capsule dosage form. XTerra C18 column was used as stationary phase with mobile phase acetonitrile in combination with 0.1% trifluoro acetic acid buffer and pH is adjusted to 1.4. Method was developed in an isocratic run of 20% trifluoro acetic acid with 80% acetonitrile for 10 min, at flow rate of 1 ml/min. Effluents were monitored at 210 nm. Retention time of cyclosporine was 3.855 min. The method was validated for specificity, linearity, accuracy, precision, limit of quantification, limit of detection, robustness and solution stability. Limit of quantification and limit of detection of cyclosporine was found to be 100 ng/ml and 200 ng/ml. Recovery was found to be in the range of 98.08-101.55%. The proposed method was successfully applied for the quantitative determination of cyclosporine in a capsule dosage form. PMID:20838535

Aziz, F.; Gupta, A.; Khan, M. F.

2010-01-01

105

Validation of a simple RP-HPLC method developed for the quantification of meta-cresol in parathyroid hormones formulation  

PubMed Central

Aim: To develop and validate a rapid and sensitive reverse phase high performance liquid chromatography (RP-HPLC) method with UV detection for quantification of meta-cresol (m-cresol) in pharmaceutical preparation of parathyroid hormone (1–34) (PTH). Materials and Methods: Chromatography was performed on a Jupiter RP C-18 (4.6 mm ID × 250 mm L, porosity 300 Å, particle size 5 ?m) with a guard column (reversed-phase C18 column of 4.6 mm ID × 12.5 mm L, porosity 300 Å, particle size 5 ?m) using a mobile phase containing 0.1% TFA in 60% methanol with isocratic program at 1.0 mL/min flow rate. Detection was carried out at 217 nm. The method was validated as per ICH guidelines for linearity (correlation coefficient = 0.99), range, accuracy, precision, and robustness (n = 9 during accuracy parameter whereas n =15 during linearity and range parameter and n = 6 during repeatability). Robustness was confirmed by considering two factors; age effect of the mobile phase and test sample and with different columns during method development. Results: The method was linear over the concentration range of 75–120 ?g/mL. The precision of the method in terms of relative standard deviation was evaluated from intra- and inter-day replicate injections of system suitability standards of m-cresol using different equipment and different columns. Components of within- and between-batch variances were found to be below 2% (n = 30) and 3%, respectively, which constituted an acceptable level of variation. Retention time was found to be about 5.2 min and 10.9 min for m-cresol and PTH, respectively. Conclusion: The developed method thus has the potential of being useful for routine quality control of m-cresol. PMID:23781457

Rane, Shaligram S.; Ajameri, Alkesh; Mody, Rustom; Padmaja, P.

2011-01-01

106

[Determination of biogenic amines by RP-HPLC for monitoring the microbial spoilage of poultry].  

PubMed

A simple high-performance liquid chromatographic (HPLC) analysis is described for the determination of biogenic amines in broiler carcasses. The clean-up procedure consists of an extraction with 0.6 M-perchloric acid, formation of dansyl derivatives, separation by a RP-18 column and UV detection at 254 nm. Within 7 min eight amines could be separated. The quantitative determination of spermidine and spermine requires an additional ion-exchange clean-up with Amberlite CG 50 after the extraction. This procedure gives recoveries of 82%-96% with detection limits of 0.2-0.5 microgram/g of broiler skin. Putrescine and cadaverine are good indicators for the onset of spoilage of poultry carcasses, since both amines could be detected at total colony counts of 10(5) cfu/cm2 and their concentration increases rapidly with advancing decomposition. PMID:3223088

Schmitt, R E; Haas, J; Amadò, R

1988-08-01

107

The Effects of Stationary Phases on Retention and Selectivity of Oligonucleotides in IP-RP-HPLC.  

PubMed

There is a growing demand for the separation and identification of short nucleic acid fragments, such as oligonucleotides. There were two main goals of the present investigation, namely, evaluation of the impact of stationary phase type and the influence of various ion-pair reagents on the retention behavior of oligonucleotides in ion-pair liquid chromatography. Three types of ion-pair reagents were studied: triethylammonium acetate, dimethylbuthylammonium acetate and mixtures of 1,1,1,3,3,3-hexafluoro-2-propanol and triethylamine. Two novel types of packing materials, namely, cholesterol and alkylamide were used for this purpose for the first time. The results indicate that the mechanism of oligonucleotides retention is determined by the hydrophobicity of ion-pair reagents and polar ligands localized on the surface of stationary phases. Oligonucleotides were most effectively separated with the use of alkylamide and cholesterol packings. These two stationary phases reduce the time of analysis in comparison with the octadecyl packing material. Moreover, separation was achieved under non-denaturating conditions. PMID:25477554

Studzi?ska, Sylwia; Pietrzak, Lidia; Buszewski, Bogus?aw

2014-01-01

108

Haemagglutinin quantification and identification of influenza A&B strains propagated in PER.C6 cells: a novel RP-HPLC method.  

PubMed

The major antigenic determinant of influenza A and B virus is haemagglutinin (HA). The HA content is an important specification of influenza vaccines. HA in vaccines has typically been quantified by single-radial-immunodiffusion (SRID). However, SRID is a laborious and low throughput assay. Moreover, sensitivity, accuracy, and precision, especially for non-purified (in-process) influenza virus is relatively low. We present a novel method for quantification of HA in influenza viral cultures as well as for the identification of HA from individual influenza strains in trivalent vaccines. The method is based on the separation of HA(1), the hydrophilic subunit of HA, from the more hydrophobic viral and matrix components by reversed-phase high performance liquid chromatography (RP-HPLC). The HA(1) peak area is demonstrated to be proportional to the level of HA in non-purified, semi-purified and purified vaccine products of various epidemic and pandemic influenza A and B strains propagated in PER.C6((R)) cell cultures. The RP-HPLC assay selectivity allows for the simultaneous identification and quantification of HA(1) from influenza A and B strains in the yearly revised trivalent vaccines for epidemic outbreaks. PMID:16490287

Kapteyn, Johan C; Saidi, Mohammed Drissi; Dijkstra, René; Kars, Cennet; Tjon, Joan C M S-K; Weverling, G J; de Vocht, Marcel L; Kompier, Ronald; van Montfort, Bart A; Guichoux, Jean-Yves; Goudsmit, Jaap; Lagerwerf, Fija M

2006-04-12

109

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

PubMed Central

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

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

2013-01-01

110

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

PubMed Central

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

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

2013-01-01

111

Purine metabolite and energy charge analysis of Trypanosoma brucei cells in different growth phases using an optimized ion-pair RP-HPLC/UV for the quantification of adenine and guanine pools.  

PubMed

Human African Trypanosomiasis (HAT) is caused by the protozoan parasite Trypanosoma brucei. Although trypanosomes are well-studied model organisms, only little is known about their adenine and guanine nucleotide pools. Besides being building blocks of RNA and DNA, these nucleotides are also important modulators of diverse biochemical cellular processes. Adenine nucleotides also play an important role in the regulation of metabolic energy. The energetic state of cells is evaluated by the energy charge which gives information about how much energy is available in form of high energy phosphate bonds of adenine nucleotides. A sensitive and reproducible ion-pair RP-HPLC/UV method was developed and optimized, allowing the quantification of guanine and adenine nucleosides/nucleotides in T. brucei. With this method, the purine levels and their respective ratios were investigated in trypanosomes during logarithmic, stationary and senescent growth phases. Results of this study showed that all adenine and guanine purines under investigation were in the low mM range. The energy charge was found to decrease from logarithmic to static and to senescent phase whereas AMP/ATP, ADP/ATP and GDP/GTP ratios increased in the same order. In addition, the AMP/ATP ratio varied as the square of the ADP/ATP ratio, indicating AMP to be the key energy sensor molecule in trypanosomes. PMID:24657574

Graven, Patricia; Tambalo, Margherita; Scapozza, Leonardo; Perozzo, Remo

2014-06-01

112

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

PubMed Central

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

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

2013-01-01

113

Optimization of forced degradation using experimental design and development of a stability-indicating liquid chromatographic assay method for rebamipide in bulk and tablet dosage form.  

PubMed

A novel stability-indicating RP-HPLC assay method was developed and validated for quantitative determination of rebamipide in bulk and tablet dosage form. Rebamipide (drug and drug product) solutions were exposed to acid and alkali hydrolysis, thermal stress, oxidation by hydrogen peroxide and photodegradation. Experimental design has been used during forced degradation to determine significant factors responsible for degradation and to obtain optimal degradation conditions. In addition, acid and alkali hydrolysis was performed using a microwave oven. The chromatographic method employed the HiQ sil C-18HS (250 × 4.6 mm; 5 ?m) column with mobile phase consisting of 0.02 M potassium phosphate (pH adjusted to 6.8) and methanol (40:60, v/v) and the detection was performed at 230 nm. The procedure was validated for specificity, linearity, accuracy, precision and robustness. There was no interference observed of excipients and degradation products in the determination of the active pharmaceutical ingredient. The method showed good accuracy and precision (intra and inter day) and the response was linear in a range from 0.5 to 5 ?g mL(-1). The method was found to be simple and fast with less trial and error experimentation by making use of experimental design. Also, it proved that microwave energy can be used to expedite hydrolysis of rebamipide. PMID:21617774

Sonawane, Sandeep; Gide, Paraag

2011-03-01

114

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

PubMed

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

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

2013-03-01

115

A novel approach for the quantitation of carbohydrates in mash, wort, and beer with RP-HPLC using 1-naphthylamine for precolumn derivatization.  

PubMed

A novel universal method for the determination of reducing mono-, di-, and oligosaccharides in complex matrices on RP-HPLC using 1-naphthylamine for precolumn derivatization with sodium cyanoborhydride was established to study changes in the carbohydrate profile during beer brewing. Fluorescence and mass spectrometric detection enabled very sensitive analyses of beer-relevant carbohydrates. Mass spectrometry additionally allowed the identification of the molecular weight and thereby the degree of polymerization of unknown carbohydrates. Thus, carbohydrates with up to 16 glucose units were detected. Comparison demonstrated that the novel method was superior to fluorophore-assisted carbohydrate electrophoresis (FACE). The results proved the HPLC method clearly to be more powerful in regard to sensitivity and resolution. Analogous to FACE, this method was designated fluorophore-assisted carbohydrate HPLC (FAC-HPLC). PMID:23578308

Rakete, Stefan; Glomb, Marcus A

2013-04-24

116

Development and validation of RP-HPLC method for simultaneous estimation of glimepiride and sildenafil citrate in rat plasma-application to pharmacokinetic studies.  

PubMed

A simple and sensitive method was developed for simultaneous estimation of Glimepiride (GLIM) and Sildenafil citrate (SIL) in rat Plasma by reverse phase high performance liquid chromatography (RP-HPLC). The drug samples were extracted by liquid-liquid extraction with 300 µl of acetonitrile and 5 ml of diethyl ether. Chromatographic separation was achieved on C18 column using methanol: water (85:15 v/v) as mobile phase at a flow rate of 1 ml/min and UV detection at 230 nm. The retention time of GLIM and SIL was found to be 2.5 and 4.0 min respectively with total run time of 7 min. The developed method was validated for accuracy, precision, linearity and recovery. The method was linear and found to be acceptable over the range of 100-12 000 ng/ml. The method was successfully applied for the analysis of rat plasma sample for application to pharmacokinetic. PMID:23884662

Tripathi, A S; Dewani, A P; Shelke, P G; Bakal, R L; Chandewar, A V; Mazumder, P M

2013-10-01

117

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

PubMed

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 (?(ex) = 280/?(em) = 350 nm). The calibration curves were linear for all of the studied compounds over the concentration range of 0.0625-125 ?g mL(-1) (r ( 2 ) ? 0.998) and the limits of detection were below 0.015 ?g mL(-1). The applicability of the method was confirmed by analysis of Pseudomonas putida culture supernatants. PMID:23111785

Szkop, Micha?; Bielawski, Wies?aw

2013-03-01

118

[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

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 related substances of raw material drug of ammonium glycyrrhizinate. It is concluded that the separation of principal component isomer of raw material drug of ammonium glycyrrhizinate and the validity of the substance's structure assignments of retention time being 1.2 in the European pharmacopoeia EP7.0 version, British pharmacopoeia 2012 version remains open to question. It may be of practical value for the quality control of raw material drug, preparation, and Chinese herbal medicine of ammonium glycyrrhizinate. PMID:24187837

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

2013-08-01

119

Optimization and validation of an RP-HPLC method for direct determination of metformin hydrochloride in human urine and in a dosage form.  

PubMed

A simple, selective, sensitive, accurate, and precise method was developed for determination of metformin hydrochloride (MF) in human urine using RP-HPLC. The method depends upon using an octylsilyl (C8) 5 microm particle size column at ambient temperature with mobile phase consisting of 33 mM sodium dihydrogen phosphate containing 6.38 mM hexanesulfonic acid sodium salt and adjusted to apparent pH 3.0 with phosphoric acid-acetonitrile (93 + 7, v/v) at a flow rate of 1.5 mL/min. Quantitation was achieved with UV detection at 231 nm based on peak area with a linear calibration curve over the concentration range of 0.01-50 microg/mL. The proposed method was applied to the determination of the urinary excretion pattern of MF (the cumulative amounts excreted were calculated without pretreatment of the urine sample) and for determination of the dissolution pattern of MF tablets. The proposed method was completely validated according to the U.S. Food and Drug Administration guidelines. PMID:21313808

El-Gindy, Alaa; Nassar, Mohammed Wafaa; El-Abasawy, Nasr Mohammed; Attia, Khalid Abdel-Salam; Al-Shabrawi, Maisra

2010-01-01

120

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

PubMed Central

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

Rocha, Bruno Alves; Bueno, Paula Carolina Pires; Vaz, Mirela Mara de Oliveira Lima Leite; Nascimento, Andresa Piacezzi; Ferreira, 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

121

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

PubMed

A reversed-phase high performance liquid chromatographic coupled to ultraviolet detection (RP-HPLC/UV) method was developed for simultaneous determination of 15 phenolic compounds and caffeine in TEAS (green tea, oolong tea, black tea and mate). Furthermore, the extraction process of total phenolic contents (TPC) from TEAS were optimized using response surface methodology (RSM) based on a central composite design (CCD) and then applied to extraction of TEAS. The best conditions obtained using the model were as follow: green tea - extraction time of 123min, extraction temperature of 70°C and ethanol concentration of 75%, oolong tea - extraction time of 98min, extraction temperature of 70°C and ethanol concentration of 69%, black tea - extraction time of 105min, extraction temperature of 71°C and ethanol concentration of 63%, and mate - extraction time of 103min, 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

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

2015-04-01

122

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

PubMed

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

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

2010-11-01

123

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

PubMed Central

A rapid and sensitive RP-HPLC method with UV detection (244 nm) for routine analysis of montelukast sodium and ebastine in a pharmaceutical formulation (Ebast-M) was developed. Chromatography was performed with mobile phase containing a mixture of methanol:acetonitrile:ammonium acetate (80:10:10, % v/v/v), pH of mobile phase was adjusted 5.5 using glacial acetic acid and flow rate was 1.2 ml/min. The method was validated for linearity, accuracy, robustness and intermediate precision. The linearity was established over the concentration range of 0.01?0.06 mg/ml for both drugs. The correlation coefficients (r2) for ebastine and montelukast were 0.9989 and 0.9955, respectively. Statistical analysis of the data showed that the method was precise, accurate, reproducible and selective for the analysis of ebastine and montelukast drugs. The method was successfully employed for the determination of ebastine and montelukast in commercially available tablet dosage form. PMID:24403662

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

2013-01-01

124

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

PubMed

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

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

2013-09-01

125

Method development and validation for simultaneous determination of lumefantrine and its major metabolite, desbutyl lumefantrine in human plasma using RP-HPLC/UV detection.  

PubMed

A simple, specific, precise and rapid RP-HPLC-UV method was developed for simultaneous determination of lumefantrine and its metabolite desbutyl lumefantrine in human plasma. Experimental parameters were optimized and the method was validated according to standard guidelines. The method showed adequate separation for lumefantrine and desbutyl lumefantrine and best resolution was achieved with Supelco Discovery HS C18 RP (150mm×4.6mm, 5?m) column using acetonitrile and 0.05% trifluroacetic acid (70:30, v/v) as a mobile phase pumped at a flow rate of 1.0ml/min and wavelength of 335nm. The method was linear over the concentration range of 10-12,000ng/ml. The lower limit of detection (LLOD) and lower limit of quantification (LLOQ) for lumefantrine were 10.0 and 18.0ng/ml, while for desbutyl lumefantrine were 7.5 and 15.0ng/ml, respectively. The proposed method was efficiently applied for determination of lumefantrine and desbutyl lumefantrine concentrations in plasma samples for pharmacokinetic studies. PMID:24316521

Khuda, Fazli; Iqbal, Zafar; Shah, Yasar; Ahmmad, Lateef; Nasir, Fazli; Khan, Amir Zada; Amanullah; Shahbaz, Naila

2014-01-01

126

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

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

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

2011-07-27

127

The effect of eluent pH and compound acid–base character on the design of generic-gradient reversed-phase high-performance liquid chromatography (RP-HPLC) methods for use in drug discovery  

Microsoft Academic Search

The design of generic reversed-phase high-performance liquid chromatography (RP-HPLC) gradient methods for the analysis of compound mixtures or ‘cocktails’ has been investigated with particular reference to the eluent pH and the type of compound (acid, base or neutral) analysed. The use of eluents with an acidic eluent pH, an approach which is widely employed, can lead to non-retention of polar

Brian Law

2004-01-01

128

Simultaneous determination of methylparaben, propylparaben, hydrocortisone acetate and its degradation products in a topical cream by RP-HPLC  

Microsoft Academic Search

A novel reversed-phase high-performance liquid chromatographic method with UV spectrophotometric detection was developed and validated for the determination of compounds in topical cream. The method describes determination of active component hydrocortisone acetate (HCA), its degradation products hydrocortisone (HC) and cortisone acetate (occurring in formulation after long-term stability tests) and two preservatives presented in the cream-methylparaben and propylparaben, using dexamethasone as

R. Hájková; P. Solich; J. Dvo?ák; J. Š??cha

2003-01-01

129

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

PubMed

A simple, sensitive and selective HPLC method with UV detection for determination of Glipizide in human plasma was developed. Liquid-liquid extraction method was used to extract the drug from the plasma samples. Chromatographic separation of Glipizide was achieved using C18 column (ZORBAX ODS 4.6 × 150 mm). The mobile phase was comprised of 0.01 M potassium dihydrogen phosphate and acetonitrile (65:35, v/v) adjusted to pH 4.25 with glacial acetic acid. The analysis was run at a flow rate of 1.5 mL/min with an injection volume was 20 ?L. The detector was operated at 275 nm. The calibration curve was linear over a concentration range of 50-1600 ng/mL. Intra-day and inter-day precision and accuracy values were below 15%. The limit of quantification was 50 ng/mL and the mean recovery was above 98%. Freeze-thaw, short-term, long-term and post-preparative stability studies showed that Glipizide in plasma sample was stable. The method may be successfully applied to analyze the Glipizide concentration in plasma samples for bioavailability and bioequivalence studies. PMID:24023449

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

2013-03-01

130

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

PubMed Central

A simple, sensitive and selective HPLC method with UV detection for determination of Glipizide in human plasma was developed. Liquid–liquid extraction method was used to extract the drug from the plasma samples. Chromatographic separation of Glipizide was achieved using C18 column (ZORBAX ODS 4.6 × 150 mm). The mobile phase was comprised of 0.01 M potassium dihydrogen phosphate and acetonitrile (65:35, v/v) adjusted to pH 4.25 with glacial acetic acid. The analysis was run at a flow rate of 1.5 mL/min with an injection volume was 20 ?L. The detector was operated at 275 nm. The calibration curve was linear over a concentration range of 50–1600 ng/mL. Intra-day and inter-day precision and accuracy values were below 15%. The limit of quantification was 50 ng/mL and the mean recovery was above 98%. Freeze-thaw, short-term, long-term and post-preparative stability studies showed that Glipizide in plasma sample was stable. The method may be successfully applied to analyze the Glipizide concentration in plasma samples for bioavailability and bioequivalence studies. PMID:24023449

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

2013-01-01

131

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

PubMed

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

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

2009-02-01

132

Validated stability-indicating methods for the simultaneous determination of amiloride hydrochloride, atenolol, and chlorthalidone using HPTLC and HPLC with photodiode array detector.  

PubMed

Two stability-indicating chromatographic methods are described for simultaneous determination of amiloride hydrochloride (AMI), atenolol (ATE), and chlorthalidone (CHL) in combined dosage forms. The first method was based on HPTLC separation of the three drugs followed by densitometric measurements of their bands at 274 nm. The separation was carried out on Merck HPTLC silica gel 60F254 aluminum sheets using chloroform-methanol-ammonia 27%, w/w (9 + 2 + 0.3, v/v/v) mobile phase. Analysis data was used for the linear regression graph in the range of 0.1-0.5, 0.8-5.0, and 0.3-1.5 microg/band for AMI, ATE, and CHL, respectively. The second method was based on an RP-HPLC separation of the cited drugs performed on an RP stainless steel C18 analytical column (250 x 4.6 mm id) with a gradient elution system of methanol and 0.05 M aqueous phosphate buffer adjusted to pH 4 as the mobile phase, at the flow rate of 1.0 mL/min. Quantitation was achieved with photodiode array detection at 275 nm for AMI and 225 nm for ATE and CHL. The calibration graphs for each drug were rectilinear in the range of 2-50, 25-150, and 2-100 microg/mL for AMI, ATE, and CHL, respectively. The proposed chromatographic methods were successfully applied for determination of the investigated drugs in pharmaceutical preparations. Both methods were validated in compliance with International Conference on Harmonization guidelines in terms of linearity, accuracy, precision, robustness, LOD, and LOQ. PMID:23767356

Youssef, Rasha M; Maher, Hadir M; El-Kimary, Eman I; Hassan, Ekram M; Barary, Magda H

2013-01-01

133

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

E-print Network

Stability and Variability: Indicators for Passive Stability and Active Control in a Rhythmic Task 12 March 2008 Wei K, Dijkstra TM, Sternad D. Stability and variability: indicators for passive stability and active control in a rhythmic task. J Neuro- physiol 99: 3027­3041, 2008. First published March

Sternad, Dagmar

134

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

PubMed Central

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??m, 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

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

2014-01-01

135

A structure-activity relationship study on the mechanisms of methacrylate-induced toxicity using NMR chemical shift of beta-carbon, RP-HPLC log P and semiempirical molecular descriptor.  

PubMed

To clarify the mechanism of methacrylate-induced toxicity, a total of 24 acrylates, methacrylates, and dimethacrylates were chosen for a structure-activity relationship (SAR) study in terms of NMR chemical shifts, semiempirical molecular descriptors, and reverse phase (RP)-HPLC log P. Molecular descriptors as well as bulk, electronic, and energy descriptors were calculated using the PM3/CONFLEX method. A significant multiple linear regression equation for methacrylates in mice was denoted as log 1/LD50 (which was function [-(E(HOMO)+E(LUMO))/2, log P]). Besides, significant linear regression equations for methacrylates were denoted as log 1/ED50 in HeLa S3 and in HGF cells as function [E(HOMO) and/or log P]. Results showed that the 13C NMR chemical shift of beta-carbon for methacrylates was correlated with their E(HOMO). Findings of this study thus suggested that it might be possible to predict methacrylate-induced toxicity using physicochemical properties. PMID:19280976

Ishihara, Mariko; Fujisawa, Seiichiro

2009-01-01

136

Development and validation of RP-HPLC method with ultraviolet detection for estimation of montelukast in rabbit plasma: Application to preclinical pharmacokinetics  

PubMed Central

Objective To develop a liquid–liquid extraction based reverse phase liquid chromatography method for estimation of montelukast in rabbit plasma. Methods Chromatographic separation was carried out using Phenomenex Luna C18 column (250 mm × 4.6 mm × 5 ?m) with mobile phase composed of ammonium acetate buffer (20 Mm), pH 5.5 and acetonitrile in 20:80, v/v ratio. The analyte was monitored with UV detector at 345 nm. The developed method was validated with respect to linearity, accuracy, precision, specificity and stability. Results The peak area ratio of montelukast (MKS) to that of internal standard was used for the quantification of samples. Calibration curves were linear in the concentration range of 20–2000 ng mL?1. The LOD and LLOQ of present method were found out to be 10 ng mL?1 and 20 ng mL?1 respectively. The intra-day and inter-day %CV values for MKS were below 6.06% and 8.43%. Intra-day and inter-day accuracies were within 95.81% and 110.90%, respectively. Extraction recoveries of drug from rabbit plasma were >66.47%. Conclusion A simple, alternative, reproducible and sensitive HPLC-UV method was developed for MKS that can be used in preclinical pharmacokinetics. PMID:24563591

Ranjan, Om Prakash; Nayak, Usha Y.; Reddy, Meka Sreenivasa; Dengale, Swapnil J.; Musmade, Prashant B.; Udupa, Nayanabhirama

2013-01-01

137

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

PubMed Central

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

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

2013-01-01

138

A validated stability indicating LC method for oxcarbazepine  

Microsoft Academic Search

The present paper describes the development of a stability indicating reversed phase liquid chromatographic (RPLC) method for oxcarbazepine in the presence of its impurities and degradation products generated from forced decomposition studies. The drug substance was subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal degradation. The degradation of oxcarbazepine was observed under base hydrolysis. The drug was found

D. B. Pathare; A. S. Jadhav; M. S. Shingare

2007-01-01

139

Determination of Rottlerin, a Natural Protein Kinases C Inhibitor, in Pancreatic Cancer Cells and Mouse Xenografts by RP-HPLC Method.  

PubMed

Rottlerin is a natural polyphenolic ketone isolated from the pericarps of Mallotus phillippinensis. In previous studies we showed that parenteral administration of rottlerin reduced tumor growth in murine xenograft models of pancreatic cancer. The aim of this study was to develop a simple and validated method for the quantitative determination of rottlerin in plasma and tumor tissues of mice fed a rottlerin diet. A xenograft model of pancreatic cancer was prepared by injection of 2×10(6) HPAF-II cells subcutaneously into nude mice. One week before tumor implantation, mice were randomly allocated to standard diet (AIN76A) and standard diet supplement with 0.012% rottlerin (n=6 per group). Mice were sacrificed after 6 weeks on diets. Rottlerin was extracted from the plasma and tissues using protein precipitation-extraction and analyzed by reverse-phase HPLC-DAD method. The same HPLC method was also applied to determine rottlerin levels in conditioned culture media and in cell lysates from HPAF-II cells exposed to 25 µM concentration of rottlerin. A substantial amount of rottlerin was detected in tumor (2.11 ± 0.25 nmol/g tissue) and plasma (2.88 ± 0.41 µM) in mice fed rottlerin diet. In addition, significant levels of rottlerin (57.4 ± 5.4 nmol/mg protein) were detected in cell lysates from rottlerin-treated HPAF-II cells. These data indicate that rottlerin is efficiently absorbed in cells and tissues both in vivo and in vitro and suggest a strong potential for rottlerin as a preventive or adjuvant supplement for pancreatic cancer. PMID:24482742

Lu, Qing-Yi; Zhang, Lifeng; Lugea, Aurelia; Moro, Aune; Edderkaoui, Mouad; Eibl, Guido; Pandol, Stephen J; Go, Vay-Liang W

2013-01-01

140

Stabilization of a recombinant human epidermal growth factor parenteral formulation through freeze-drying.  

PubMed

Development studies were performed to design a pharmaceutical composition that allows the stabilization of a parenteral rhEGF formulation in a lyophilized dosage form. Unannealed and annealed drying protocols were tested for excipients screening. Freeze-dry microscopy was used as criterion for excipients and formulation selection; as well as to define freeze-drying parameters. Excipients screening were evaluated through their effect on freeze-drying recovery and dried product stability at 50 °C by using a comprehensive set of analytical techniques assessing the chemical stability, protein conformation and bioactivity. The highest stability of rhEGF during freeze-drying was achieved by the addition of sucrose or trehalose. After storing the dried product at 50 °C, the highest stability was achieved by the addition of dextran, sucrose, trehalose or raffinose. The selected formulation mixture of sucrose and dextran could prevent protein degradation during the freeze-drying and delivery processes. The degradation rate assessed by RP-HPLC could decrease 100 times at 37 °C and 70 times at 50 °C in dried with respect to aqueous formulation. These results indicate that the freeze-dried formulation represents an appropriate technical solution for stabilizing rhEGF. PMID:25190208

Santana, Héctor; Sotolongo, Jorge; González, Yaima; Hernández, Gerardo; Chinea, Glay; Gerónimo, Haydée; Amarantes, Odalys; Beldarraín, Alejandro; Páez, Rolando

2014-11-01

141

Development of a Validated Stability Indicating LC Method for Lamotrigine  

Microsoft Academic Search

The present method provides the detailed description of development of a simple, time efficient stability indicating reversed\\u000a phase column liquid chromatographic method for lamotrigine in the presence of its impurities namely Imp-A, Imp-B, Imp-C, Imp-D,\\u000a Imp-E, Imp-F and degradation products generated from forced decomposition studies. The drug substance was subjected to stress\\u000a conditions of aqueous hydrolysis, oxidative, photolytic and thermal

Polisetty Srinivasulu; Khagga Mukkanti; Buchi Reddy Reguri; Koduri S. V. Srinivas

2009-01-01

142

A validated stability indicating HPTLC method for determination of nitazoxanide  

Microsoft Academic Search

A simple, selective, precise and stability-indicating high-performance thin-layer chromatographic (HPTLC) method for nitazoxanide in bulk drug and in formulations was developed and validated. Method employed TLC aluminium plates precoated with silica gel 60F-254 as the stationary phase. Solvent system consisted of ethyl acetate-toluene- methanol (4:6:1, v\\/v\\/v). Nitazoxanide was subjected to hydrolysis, oxidation, photolysis and thermal decomposition to establish a validated

C L Gopu; Shibu Thomas; A R Paradkar; K R Mahadik

143

A Validated, Stability-Indicating, LC Method for Rabeprazole Sodium  

Microsoft Academic Search

A simple, economic, and time-efficient stability-indicating, reversed-phase high-performance liquid chromatographic method\\u000a has been developed for analysis of rabeprazole in the presence both of impurities and of degradation products generated by\\u000a decomposition. When rabeprazole was subjected to acid hydrolytic, oxidative, photolytic, and thermal stress, degradation was\\u000a observed after acid hydrolysis, oxidation, and aqueous hydrolysis. The drug was found to be stable

Reguri Buchireddy; Khagga Mukkanti; Polisetty Srinivasulu; Koduri S. V. Srinivas

2008-01-01

144

Development of an HPLC method for measurements of the stability of Irganox-type polymer antioxidants in fatty food simulants  

Microsoft Academic Search

A reversed-phase high-performance liquid chromatography (RP-HPLC) method has been developed to measure the stability of four\\u000a Irganox-type polymer antioxidants (Irganox 245, Irganox 1035, Irganox 1098 and Irganox 3114) in an olive oil food simulant\\u000a and isooctane, which has been proposed as an alternative fatty food simulant. The tests of stability in olive oil were carried\\u000a out under three different conditions,

P. G. Demertzis; R. Franz

1998-01-01

145

Development of stability-indicating methods for cefquinome sulphate.  

PubMed

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

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

2013-09-01

146

Development of Stability-Indicating Methods for Cefquinome Sulphate  

PubMed Central

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

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

2013-01-01

147

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

PubMed

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

Saini, Balraj; Bansal, Gulshan

2014-06-01

148

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

PubMed Central

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

Saini, Balraj; Bansal, Gulshan

2014-01-01

149

Evaluation of time stability indices for soil water storage upscaling  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

150

Screening for stability and compatibility conditions of recombinant human epidermal growth factor for parenteral formulation: effect of pH, buffers, and excipients.  

PubMed

A successful parenteral formulation can be developed by studying stability and compatibility of biopharmaceuticals as a function of solution composition. Here, we evaluate the influence of pH, buffers, ionic strength, protein concentration and presence of excipients on recombinant human epidermal growth factor (rhEGF) stability. The stability was accessed by reversed-phase high performance liquid chromatography (RP-HPLC), size exclusion chromatography (SEC-HPLC), enzyme-linked immunosorbent assay (ELISA), Far-UV circular dichroism (CD) and light scattering. The overall maximal stability was obtained in pH near to 7.0 in phosphate, Tris and histidine buffers as the results of the different methods revealed. The CD results revealed that this protein is stable in an extensive pH range. Aggregation of rhEGF was minimized at pH values ranged from 6.0 to 8.0 as indicated the SEC-HPLC and light scattering results. Nor the ionic strength neither the rhEGF concentration had significant effect on the reaction rate constants. Most rhEGF-excipient instability occurs among this protein and reducing sugars. Polymers like poly(ethylene glycol) (PEG) and polysorbates increased methionine oxidation. The rhEGF oxidation and deamidation were the most common degradation pathways. This research identified critical solution factors to be considered for the development of a successful rhEGF parenteral formulation. PMID:23624083

Santana, Héctor; González, Yaima; Campana, Patricia Targon; Noda, Jesús; Amarantes, Odalys; Itri, Rosangela; Beldarraín, Alejandro; Páez, Rolando

2013-08-16

151

Stabilities of neutral and basic esters of bendamustine in plasma compared to the parent compound: Kinetic investigations by HPLC.  

PubMed

Esters of the cytostatic bendamustine (1), previously demonstrated to be much more potent than the parent compound as antiproliferative agents in vitro, were investigated for stability in buffer and plasma, as well as against porcine liver esterase in the presence of different amounts of albumin using a validated RP-HPLC method with fluorescence detection. The hydrolysis of the nitrogen mustard moiety was retarded (for 1: approximately 130 vs. 11min) in the presence of plasma proteins. For the derivatives, both cleavage of ester and nitrogen mustard moieties were analyzed. Enzymatic hydrolysis was very fast in the case of 2-pyrrolidino-, 2-piperidino- and 2-(4-methylpiperazino)-ethyl esters, whereas methyl, ethyl, morpholinoethyl and branched 2-pyrrolidinoethyl esters were considerably more stable (half-lives between 41 and 116min, compared to <5min). Inhibition by physostigmine indicated unspecific cholinesterases to be involved in the rapid ester cleavage. Due to lower protein content and higher enzymatic activity in murine compared to human plasma, reduced stability of all investigated esters in mouse plasma (t½<2min) has to be taken into account with respect to the design of animal studies. PMID:25499654

Huber, S; Antoni, F; Schickaneder, C; Schickaneder, H; Bernhardt, G; Buschauer, A

2015-02-01

152

Herring gull eggs indicate stabilizing Great Lakes PCB concentrations  

SciTech Connect

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

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

1995-12-31

153

The Stability of School Effectiveness Indices across Years.  

ERIC Educational Resources Information Center

School effectiveness indices (SEIs) based on residuals from regressing test performance in reading and mathematics onto prior-year test performance and a socioeconomic status measure (percentage eligible for a subsidized lunch program) were obtained for two consecutive years for 431 South Carolina elementary schools. The analysis involved school…

Mandeville, Garrett K.

154

Development and validation of a stability-indicating HPLC method for simultaneous determination of salicylic acid, betamethasone dipropionate and their related compounds in Diprosalic Lotion ®  

Microsoft Academic Search

Diprosalic Lotion® is an anti-inflammatory drug product that contains salicylic acid and betamethasone dipropionate as active pharmaceutical ingredients (APIs). A reversed-phase high performance liquid chromatography (RP-HPLC) method was developed for simultaneous determination of salicylic acid, betamethasone dipropionate, and their related compounds in Diprosalic Lotion®. A 150mm×4.6mm I.D. YMC J'sphere ODS-H80 column at 35°C and UV detection at 240nm was used.

Minshan Shou; Wilmer A. Galinada; Yu-Chien Wei; Qinglin Tang; Robert J. Markovich; Abu M. Rustum

2009-01-01

155

Regulatory Aspects in Development of Stability-Indicating Methods: A Review  

Microsoft Academic Search

The main contemporary goal of stability-indicating methods (SIMs) is to provide information about the conditions for stress\\u000a testing so as to establish the stability of drug substances and products. This paper reviews the regulatory aspects for development\\u000a of stability-indicating methods. SIMs are used to differentiate the active pharmaceutical ingredient (API) from its potential\\u000a decomposition products. Regulatory guidance in ICH Q1AR2,

Renu Sehrawat; Mukesh Maithani; Ranjit Singh

2010-01-01

156

Stability-indicating chromatographic methods for the determination of sertindole.  

PubMed

In this work, two chromatographic methods have been developed and validated for the determination of sertindole (an antipsychotic agent) in the presence of its oxidative degradation product. Sertindole was subjected to stress stability studies, including acid, alkali, oxidative, photolytic and thermal degradation. The chromatographic methods included the use of thin-layer chromatography (TLC-densitometry) and high-performance liquid chromatography (HPLC). The TLC method employed aluminum TLC plates precoated with silica gel G.F254 as the stationary phase and methanol-ethyl acetate-33% ammonia (1:9:0.1, by volume) as the mobile phase, and the chromatograms were scanned at 227 nm. The developed HPLC method used a reversed-phase C18 column with isocratic elution. The mobile phase was composed of phosphate buffer pH 3.0-acetonitrile-triethylamine (45:55:0.03, by volume) and run at a flow rate of 1.0 mL/min. Quantitation was achieved with ultraviolet detection at 256 nm. The linearity ranges were found to be 2-14 µg/band and 5-200 µg/mL for TLC and HPLC, respectively. The developed methods were validated according to the International Conference on Harmonization guidelines and were applied for bulk powder and dosage forms. PMID:23733912

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

2014-07-01

157

Environmental stability of PAH source indices in pyrogenic tars  

SciTech Connect

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.

Uhler, A.D.; Emsbo-Mattingly, S.D. [New Fields Environmental Forensics Practice, Rockland, MA (United States)

2006-04-15

158

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

SciTech Connect

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.

Zimmerman, R.A.

1991-01-01

159

Fast and environmentally friendly quantitative analysis of active agents in anti-diabetic tablets by an alternative laser-induced breakdown spectroscopy (LIBS) method and comparison to a validated reversed-phase high-performance liquid chromatography (RP-HPLC) method.  

PubMed

Laser-induced breakdown spectroscopy (LIBS) is evaluated as a potential analytic technique for rapid screening and quality control of anti-diabetic tablets. This paper proposes a simple LIBS-based method for the quantitative analysis of two active pharmaceutical ingredients (APIs): metformin (Met) and glybenclamide (Gly). In order to quantify both APIs, chlorine (Cl) concentration was estimated by employing the Cl/Br optical emission ratio, where Br was introduced as internal standard. Calibration curves were prepared, achieving linearity higher than 99%. On the other hand, for comparison to the proposed method, an isocratic reversed-phase high-performance liquid chromatography (RP-HPLC) method was also developed for quantitative determination of the same analytes by ultraviolet (UV) detection. The chromatographic separation was achieved on a Phenomenex Hypersil C18, 250 mm × 4.6 mm, 5 ?m column. The mobile phase was K(2)HPO(4)/H(3)PO(4)-CH(3)OH and flow rate was 1.0 mL min(-1). The method is linear over a range of 10-60 ?g mL(-1) for Gly and 5-30 ?g mL(-1) for Met and the correlation coefficients were ?0.99. Recoveries were found to be in the range of 95-101%. Furthermore, four different commercial brands of each active agent were evaluated by both proposed LIBS and chromatographic methods and results were compared with each other. The comparison was satisfactorily validated by analysis of variance (ANOVA). PMID:23146185

Contreras, Victor Ulises; Meneses-Nava, Marco A; Ornelas-Soto, Nancy; Barbosa-García, Oracio; López-de-Alba, Pedro L; Maldonado, José L; Ramos-Ortiz, Gabriel; Acevedo-Aguilar, Francisco J; López-Martínez, Leticia

2012-11-01

160

Influence of the transient stability performance indices on a contingency screening and ranking algorithm  

Microsoft Academic Search

In this paper it is studied the influence of the transient stability performance indices on a contingency screening and ranking algorithm. The proposed methodology consists of three modules, with different complexity levels. Due to the large number of contingencies scenarios and calculations required, the application of a hybrid method to assess the system stability reduces drastically the computing time. The

C. M. M. Ferreira; F. P. Maciel Barbosa

2009-01-01

161

Development of validated stability-indicating assay methods—critical review  

Microsoft Academic Search

This write-up provides a review on the development of validated stability-indicating assay methods (SIAMs) for drug substances and products. The shortcomings of reported methods with respect to regulatory requirements are highlighted. A systematic approach for the development of stability-indicating methods is discussed. Critical issues related to development of SIAMs, such as separation of all degradation products, establishment of mass balance,

Monika Bakshi; Saranjit Singh

2002-01-01

162

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

PubMed

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

Khan, Wahid; Kumar, Neeraj

2011-06-01

163

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

PubMed Central

Human ?-hemoglobin stabilizing protein (AHSP) is a conserved mammalian erythroid protein that facilitates the production of Hemoglobin A by stabilizing free ?-globin. AHSP rapidly binds to ferrous ? with association (k?AHSP) and dissociation (kAHSP) rate constants of ?10 ?m?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 ?CO. 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 ?CO was mixed with P30A and P30W AHSP, which are fixed in the trans conformation. This slow phase was also absent when met(Fe3+)-? reacted with wild-type AHSP, suggesting that met-? is capable of rapidly binding to either Pro30 conformer. Both wild-type and Pro30-substituted AHSPs drive the formation of a met-? hemichrome conformation following binding to either met- or oxy(Fe2+)-?. The dissociation rate of the met-?·AHSP complex (kAHSP ? 0.002 s?1) is ?100-fold slower than that for ferrous ?·AHSP complexes, resulting in a much higher affinity of AHSP for met-?. Thus, in vivo, AHSP acts as a molecular chaperone by rapidly binding and stabilizing met-? hemichrome folding intermediates. The low rate of met-? dissociation also allows AHSP to have a quality control function by kinetically trapping ferric ? and preventing its incorporation into less stable mixed valence Hemoglobin A tetramers. Reduction of AHSP-bound met-? allows more rapid release to ? subunits to form stable fully, reduced hemoglobin dimers and tetramers. PMID:22298770

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

2012-01-01

164

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

ERIC Educational Resources Information Center

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

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

2005-01-01

165

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

NASA Technical Reports Server (NTRS)

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.

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

1985-01-01

166

Stress degradation studies on betahistine and development of a validated stability-indicating assay method  

Microsoft Academic Search

The purpose of this work was to study the stability of betahistine (BET) at different stress conditions and to develop a sensitive stability-indicating high-performance liquid chromatographic (HPLC) assay method. The stress conditions applied were including the effect of heat, moisture, acid–base, and ultra-violet (UV) light. Betahistine and its decomposition products were derivatized by reaction with dansyl chloride (Dan-Cl) and analyzed

Alaa Khedr; Mahmoud Sheha

2008-01-01

167

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

PubMed Central

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

Akbari, Asghar; Sarmadi, Alireza; Zafardanesh, Parisa

2014-01-01

168

A validated stability-indicating HPLC method for analysis of glabridin prodrugs in hydrolysis studies  

Microsoft Academic Search

A simple, selective and precise stability- indicating HPLC method for determination of glabridin diacetate and dihexanoate prodrugs was developed, validated and applied to the enzymatic and chemical hydrolysis studies. The chromatographic separation was achieved on a reverse phase C18 (Thermo Hypersil-Keystone, 250 × 4.6 mm, 5 micron) column using the mixture of acetonitrile and water as mobile phase. Elution of

Warunee Jirawattanapong; Ekarin Saifah; Chamnan Patarapanich

2009-01-01

169

A validated HPLC stability-indicating method for the determination of diacerhein in bulk drug substance  

Microsoft Academic Search

A novel stability-indicating high-performance liquid chromatographic (HPLC) method was developed and validated for the assay of diacerhein in bulk forms. Diacerhein was found to degrade in alkaline and acidic conditions and also under oxidative stress. The drug was stable to dry heat and in presence of light. Resolution of drug, its potential impurities and degradation products were achieved on a

Valerio Giannellini; Francesco Salvatore; Gianluca Bartolucci; Silvia A. Coran; Massimo Bambagiotti-Alberti

2005-01-01

170

RP-HPLC ANALYSES OF GLIADINS IN MACEDONIAN WHEAT VARIETIES  

Technology Transfer Automated Retrieval System (TEKTRAN)

HPLC is an analytical method that is widely used for identification of wheat and other cereal varieties. It is also used for determination and prediction of quality, for studies of interactions and processing of cereal proteins, and as a preparative method for cereal proteins and for their characte...

171

Determination of flavonoids in Semen Cuscutae by RP-HPLC  

Microsoft Academic Search

Flavonoids contents in 40 samples of Semen Cuscutae collected from areas all around China were investigated. Five principal flavonoids, quercetin 3-O-?-d-galactoside-7-O-?-d-glucoside, quercetin 3-O-?-d-apiofuranosyl-(1?2)-?-d-galactoside, hyperoside, quercetin and kaempferol were analyzed simultaneously by using a reversed phase liquid chromatograph system with 0.025 M phosphoric acid–methanol as mobile phase. The recovery of the method was 97.0–102.9%, and all the flavonoids showed good linearity

Min Ye; Yan Li; Yuning Yan; Huwei Liu; Xiuhong Ji

2002-01-01

172

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 ...

173

Stability-Indicating HPTLC Method for Simultaneous Determination of Ezetimibe and Simvastatin  

Microsoft Academic Search

Simvastatin and ezetimibe are used to treat hyperlipidemia. A simple, selective and stability-indicating HPTLC method has\\u000a been established for analysis of simvastatin and ezetimibe. The method has been validated so that both drugs can routinely\\u000a be analyzed simultaneously. The method uses aluminum-backed silica gel 60F254 TLC plates as stationary phase with n-hexane–acetone 6:4 (v\\/v) as mobile phase. Densitometric analysis of

Rahul P. Dixit; Chandrashekhar R. Barhate; Mangal S. Nagarsenker

2008-01-01

174

A MARKER-BASED STABILITY INDICATING HIGH PERFORMANCE THIN LAYER CHROMATOGRAPHIC METHOD FOR VITEX TRIFOLIA  

Microsoft Academic Search

Casticin, chrysoplenol-D, p-hydroxy benzoic acid, and p-methoxy benzoic acid are representative flavonoids and benzoic acid derivatives in Vitex trifolia, a well-known traditional Chinese, as well as ayurvedic medicine, with a wide range of biological activities. In the present paper, the aforementioned four markers were isolated and simultaneously quantified by TLC densitometric method. In the present study, a novel stability-indicating high-performance

N. Tiwari; D. Yadav; S. C. Singh; M. M. Gupta

2011-01-01

175

Stress Degradation Studies on Aripiprazole and Development of a Validated Stability Indicating LC Method  

Microsoft Academic Search

The present paper describes the development of a stability indicating reversed phase column liquid chromatographic method\\u000a for aripiprazole in the presence of its impurities and degradation products generated from forced decomposition studies. The\\u000a drug substance was subjected to stress conditions of aqueous hydrolysis, oxidative, photolytic and thermal stress degradation.\\u000a The degradation of aripiprazole was observed under acid hydrolysis and peroxide.

Koduri S. V. Srinivas; Reguri Buchireddy; Gutta Madhusudhan; Khagga Mukkanti; Polisetty Srinivasulu

2008-01-01

176

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

Microsoft Academic Search

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

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

2011-01-01

177

A Validated Stability Indicating HPTLC Method for Determination of Cephalexin in Bulk and Pharmaceutical Formulation  

Microsoft Academic Search

A simple, specific, precise and stability-indicating high performance thin layer chromatographic method of analysis of Cephalexin, both as a bulk drug and in formulation was developed and validated. The method employed TLC (Thin Layer Chromatography) aluminum plates pre-coated with silica gel 60 F 254 as the stationary phase. The solvent system consisted of Ethyl Acetate : Methanol : Ammonia (6:4:1,

R. M. Jeswani; P. K. Sinha; M. C. Damle

178

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

Microsoft Academic Search

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

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

2011-01-01

179

A validated stability-indicating UPLC method for desloratadine and its impurities in pharmaceutical dosage forms  

Microsoft Academic Search

A novel stability-indicating gradient reverse phase ultra-performance liquid chromatographic (RP-UPLC) method was developed for the determination of purity of desloratadine in presence of its impurities and forced degradation products. The method was developed using Waters Aquity BEH C18 column with mobile phase containing a gradient mixture of solvents A and B. The eluted compounds were monitored at 280nm. The run

Dantu Durga Rao; N. V. Satyanarayana; A. Malleswara Reddy; Shakil S. Sait; Dinesh Chakole; K. Mukkanti

2010-01-01

180

STRESS DEGRADATION STUDIES ON MEBEVERINE HYDROCHLORIDE AND DEVELOPMENT OF A VALIDATED STABILITY INDICATING UPLC METHOD  

Microsoft Academic Search

A simple, economic, and time-efficient stability-indicating, reverse-phase ultra-performance liquid chromatographic (RP-UPLC) method has been developed for analysis of mebeverine hydrochloride in the presence of both impurities and degradation products generated by forced degradation. When mebeverine hydrochloride was subjected to acid hydrolytic, oxidative, base hydrolysis, photolytic, and thermal stress, degradation was observed only in base hydrolysis. The drug was found to

V. Srinivasan; H. Sivaramakrishnan; B. Karthikeyan; T. S. Balaji; S. Vijayabaskar

2011-01-01

181

A Validated Stability Indicating LC Method for Mitotane in Bulk Drugs and Pharmaceutical Dosage Forms  

Microsoft Academic Search

A novel, sensitive, stability indicating RP-LC method has been developed for the quantitative determination of mitotane, its\\u000a impurity in both bulk drugs and pharmaceutical dosage forms. Efficient chromatographic separation was achieved using a C18\\u000a stationary phase with simple mobile phase combination delivered in an isocratic mode and quantitation was by ultraviolet detection\\u000a at a wavelength of 230 nm. The mobile phase

Ravi Kiran Kaja; K. V. Surendranath; P. Radhakrishnanand; P. V. V. Satyanarayana

2009-01-01

182

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

Microsoft Academic Search

Two stability-indicating spectrofluorimetric methods have been developed for the determination of ezetimibe and olmesartan\\u000a medoxomil, drugs affecting the cardiovascular system, and validated in the presence of their degradation products. The first\\u000a method, for ezetimibe, is based on an oxidative coupling reaction of ezetimibe with 3-methylbenzothiazolin-2-one hydrazone\\u000a hydrochloride in the presence of cerium (IV) ammonium sulfate in an acidic medium. The

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

2011-01-01

183

A validated stability-indicating HPLC method for the determination of PEGylated puerarin in aqueous solutions  

Microsoft Academic Search

The aim of this study was to develop a validated specific stability-indicating HPLC method for the quantitative determination of PEGylated puerarin (PEG-PUE) in aqueous solutions. The method was validated by subjecting PEG-PUE to forced degradation under stress conditions of acid, alkali, water hydrolysis, and oxidation. Both PEG-PUE and puerarin (PUE) were simultaneously determined and separated on CAPCELL PAK C18 column

Xinyi Liu; Boyang Yu; Naijie Wang; Bei Zhang; Feng Du; Cheng He; Zuguang Ye

2010-01-01

184

Development and Validation of a Stability-Indicating LC Method for Curcumin  

Microsoft Academic Search

A simple, isocratic, stability-indicating liquid chromatographic method for quantitative determination of curcumin was successfully\\u000a developed. The chromatographic separations were achieved using a Hi-Q-Sil C18; 4.6 mm × 250 mm and 10 ?m particle size column\\u000a employing acetonitrile and acetate buffer (pH 3.0; 60: 40, v\\/v) as the mobile phase. The analyte was subjected to acidic, basic, oxidative, thermal and photo degradation. The method was\\u000a validated

Prajakta P. Dandekar; Vandana B. Patravale

2009-01-01

185

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

NASA Astrophysics Data System (ADS)

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 ?com1 and ?com2 of the Comptonized components are almost constant, ?com1 and ?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 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 ?com increases during a spectral evolution from the low state to the high state and ultimately saturates at a high mass accretion rate.

Seifina, Elena; Titarchuk, Lev; Frontera, Filippo

2013-03-01

186

Application of a validated stability-indicating chromatographic method to evaluate the reproducibility between batches of small peptides in solution  

Microsoft Academic Search

A stability-indicating reversed-phase high-performance liquid chromatographic method was developed and validated as per the International Conference on Harmonization (ICH) guidelines to evaluate the reproducibility of batches of synthetic peptides included in a stability program, in particular cholecystokinin (CCK-4) peptide.Both isothermal and nonisothermal approaches were used to determine stability under experimental conditions and the resulting degradation products were identified by liquid

Alexis Oliva; Matías Llabrés; José B. Fariña

2010-01-01

187

Stress degradation study on sulfadimethoxine and development of a validated stability-indicating HPLC assay.  

PubMed

Sulfadimethoxine was subjected to different International Conference on Harmonisation prescribed stress conditions (hydrolysis, oxidation and photolysis). A stability-indicating high-performance liquid chromatography method was developed for analysis of the drug in the presence of its major degradation products. It involved a Knauer Eurospher C18 thermostated column at 25°C, and 9.57 mM phosphate buffer (pH adjusted to 2.0 with orthophosphoric acid)-acetonitrile (70:30 v/v) as mobile phase. The mobile phase flow rate and sample volume injected were 1.2 mL/min and 20 ?L respectively. The selected wavelength for the determination was 248 nm. The method was validated for its linearity, precision, accuracy, specificity and selectivity, and then applied to the assay of sulfadimethoxine in pharmaceutical formulations. The results of the study show that sulfadimethoxine is highly sensitive to basic hydrolysis and oxidation. The mechanisms and schemas of hydrolytic, oxidative and photolytic degradation are also studied. The method developed, which separates all of the most degradation products, is simple, accurate, precise and specific. Thus, it can be applied to study the stability of veterinary preparations containing sulfadimethoxine. PMID:21440101

Louati, K; Mistiri, F; Kallel, M; Safta, F

2011-03-01

188

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

PubMed

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

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

2014-01-01

189

Stability-indicating UPLC method for determining related substances and degradants in dronedarone.  

PubMed

A simple, sensitive and reproducible method was developed on ultra-performance liquid chromatography coupled with photodiode array detection for the quantitative determination of dronedarone hydrochloride (DRO) in drug substance and pharmaceutical dosage forms. The method is applicable for the quantification of related substances and assays of drug substances. Chromatographic separation was achieved on Acquity UPLC BEH C8 100 mm, 2.1 mm and 1.7 µm columns, using gradient elution within a short run time of 10.0 min. The eluted compounds were monitored at 288 nm, the flow rate was 0.5 mL/min and the column oven temperature was maintained at 40°C. The resolution of DRO and 11 impurities (potentials and by-products) was greater than 2.0 for all pairs of components. The high correlation coefficient value (>0.9995) indicates the clear correlations between the concentrations of investigated compound and their peak areas within the test ranges. The repeatability and intermediate precision, expressed by the relative standard deviation, were less than 2.5%. The accuracy and validity of the method were further ascertained by performing recovery studies via a spike method. The accuracy of the method, expressed as relative error, was satisfactory. No interference was observed from concomitant substances normally added to the tablets. DRO was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. DRO was found to degrade significantly in acid and base stress conditions and to remain stable in thermal, photolytic degradation, oxidative and hydrolytic conditions. The degradation products were well resolved from primary peak and its impurities, proving that the method is stability indicating. The developed method was validated as per International Conference on Harmonization guidelines with respect to specificity, limit of detection, limit of quantification, linearity, accuracy, precision, solution stability and robustness. This method is also suitable for the determination of DRO drug substance and pharmaceutical dosage forms. PMID:23863770

Pydimarry, Surya Prakash Rao; Cholleti, Vijay Kumar; Vangala, Ranga Reddy

2014-08-01

190

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

PubMed Central

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

2012-01-01

191

Development and validation of a stability-indicating analytical method for the quantitation of oxytocin in pharmaceutical dosage forms  

Microsoft Academic Search

A single stability-indicating assay for oxytocin (OT) in pharmaceutical dosage forms using gradient elution over 21min has been reported in the literature. Furthermore, published and compendial methods for the analysis of OT containing dosage forms also involve using HPLC with gradient elution and complicated mobile phases that include hydrophobic ion pairing agents. A simple isocratic and stability-indicating assay was developed

F. A. Chaibva; R. B. Walker

2007-01-01

192

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

SciTech Connect

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

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

2013-03-20

193

Labeling, Stability and Biodistribution Studies of 99mTc-cyclized Tyr3-octreotate Derivatives  

PubMed Central

Introduction To probe the interplay between radiotracer stability and somatostatin receptor affinity, Tyr3-octreotate and six variations of its peptide sequence, for which the Re-cyclized products were previously reported, were radiolabeled with 99mTc and investigated for their in vitro stability. Methods Radiolabeling of the peptides was effected by ligand exchange from 99mTc-glucoheptonate, and the desired products were purified by radio-RP-HPLC. The in vitro stability in phosphate-buffered saline, mouse serum, and cysteine solutions at physiological temperature and pH for all seven 99mTc-cyclized peptides was determined by radio-RP-HPLC and radio-TLC. Normal CF-1 mouse biodistribution studies were performed for three of the 99mTc-cyclized peptides. Results Based on the fully characterized Re-cyclized peptide analogues, four 99mTc-coordination motifs were proposed for the 99mTc-cyclized peptides. Technetium-99m-cyclized Tyr3-octreotate derivatives with N2S2 metal coordination modes and large metal ring sizes were susceptible to oxidation and loss of 99mTc in the form of 99mTcO4?, as evidenced by their instability in the various solutions under physiological conditions (15–58% intact at 24 h). As anticipated, the addition of a third cysteine to the sequence stabilized the 99mTc metal coordination, and peptides with NS3 coordination modes remained >85% intact out to 24 h. No significant differences were observed in the biodistribution studies performed with three peptides of varying stabilities. Conclusions Improvements in stability were not sufficient to outweigh the low somatostatin receptor affinity for the peptides in this study. Further improvements in the peptide sequence and/or metal coordination are needed to result in a radiodiagnostic/radiotherapeutic pair for targeting the somatostatin receptor. PMID:21531292

Bigott-Hennkens, Heather M.; Dannoon, Shorouk F.; Noll, Samantha M.; Ruthengael, Varyanna C.; Jurisson, Silvia S.; Lewis, Michael R.

2010-01-01

194

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

PubMed

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

Gupta, Sakshi; Bansal, Gulshan

2011-01-01

195

Validation and application of a stability-indicating HPLC method for the in vitro determination of gastric and intestinal stability of venlafaxine  

Microsoft Academic Search

Gastrointestinal stability of venlafaxine was evaluated in vitro in simulated gastric (SGF) and intestinal (SIF) fluids using a stability indicating HPLC method. The method was validated using a 5?m Ascentis® C18 column (150mm×4.6mm) and mobile phase consisting of 30% acetonitrile in 20mM potassium phosphate buffer (pH 6.5) delivered isocratically at a flow rate of 1mL\\/min with UV detection at 228nm.

Ebenezer B. Asafu-Adjaye; Patrick J. Faustino; Mobin A. Tawakkul; Lawrence W. Anderson; Lawrence X. Yu; Hyojong Kwon; Donna A. Volpe

2007-01-01

196

Bioremediation of contaminated lake sediments and evaluation of maturity indicies as indicators of compost stability.  

PubMed

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. iBioremediatio nî, 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/oxidizable carbon), sorption capacity index (CEC/oxidizable carbon). Enzyme activities of agricultural interest like urease, phosphatase, P-glucosidase, dehydrogenase and BAA-hydrolyzing protease, which are involved in the nitrogen, phosphorus and carbon cycles, were also assessed. Total content of macro and micronutrients in the final compost was also determined to assess the fertilizer value. The studies revealed that composting could be applied as a remediation technology after removing the top sediment. The maturity indices that are evaluated from the present study can be used to validate the success of the remediation technology. PMID:16705825

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

2005-08-01

197

Application of stability-indicating HPTLC method for quantitative determination of metadoxine in pharmaceutical dosage form.  

PubMed

A sensitive, selective, precise and stability-indicating high-performance thin-layer chromatographic method for analysis of metadoxine both as a bulk drug and in formulations was developed and validated. The method employed TLC aluminium plates precoated with silica gel 60F-254 as the stationary phase. The solvent system consisted of acetone-chloroform-methanol-ammonia (7.0:4.0:3.0:1.2, v/v/v/v). Densitometric analysis of metadoxine was carried out in the absorbance mode at 315 nm. This system was found to give compact spots for metadoxine (Rf value of 0.45+/-0.02, for six replicates). Metadoxine was subjected to acid, alkali and neutral hydrolysis, oxidation, dry and wet heat treatment and photo and UV degradation. The drug undergoes degradation under all stress conditions. Also, the degraded products were well resolved from the pure drug with significantly different Rf values. The method was validated for linearity, precision, robustness, LOD, LOQ, specificity and accuracy. Linearity was found to be in the range of 100-1500 ng/spot with significantly high value of correlation coefficient r2=0.9997+/-1.02. The linear regression analysis data for the calibration plots showed good linear relationship with r2=0.9999+/-0.58 in the working concentration range of 200-700 ng/spot. The mean value of slope and intercept were 0.11+/-0.04 and 18.73+/-1.89, respectively. The limits of detection and quantitation were 50 and 100 ng/spot, respectively. Statistical analysis proves that the method is repeatable and specific for the estimation of the said drug. As the method could effectively separate the drug from its degradation products, it can be employed as a stability-indicating one. Moreover, the proposed HPTLC method was utilized to investigate the kinetics of acid and base degradation process. Arrhenius plot was constructed and activation energy was calculated respectively for acid and base degradation process. PMID:15848212

Kaul, Neeraj; Agrawal, Himani; Patil, Bharat; Kakad, Abhijit; Dhaneshwar, S R

2005-04-01

198

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

NASA Astrophysics Data System (ADS)

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.

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

199

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

NASA Astrophysics Data System (ADS)

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, ?em, of 345 nm with the excitation wavelength, ?ex, 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 ?em = 360 nm with ?ex = 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.

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

2011-01-01

200

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

PubMed

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

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

2010-03-01

201

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

PubMed Central

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 ?g/ml and 24-120 ?g/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

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

2013-01-01

202

Stability indicating LC-method for estimation of paracetamol and lornoxicam in combined dosage form.  

PubMed

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

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

2011-03-01

203

Tunable release of clavam from clavam stabilized gold nanoparticles - Design, characterization and antimicrobial study.  

PubMed

A facile one-step approach is developed to synthesize highly stable (up to 6months) gold nanoparticles (GNPs) using Clavam, pharmaceutical form of amoxicillin which contains a mixture of amoxicillin and potassium salt of clavulanic acid, at room temperature (25-30°C). The clavam stabilized GNPs are characterized using various techniques including UV-Visible, FT-IR spectrophotometry and transmission electron microscopy (TEM). Tunable release of clavam from clavam stabilized GNPs is demonstrated using intracellular concentrations of glutathione (GSH). The process is monitored using an UV-Vis spectroscopy and the amount of clavam released in terms of amoxicillin concentration is quantitatively estimated using reverse phase high performance liquid chromatographic (RP-HPLC) technique. In vitro study reveals that the clavam released from GNPs' surface was found to show a significant enhancement in antibacterial activity against Escherichia coli and the cause of enhancement is addressed. PMID:25686977

Manju, V; Dhandapani, P; Gurusamy Neelavannan, M; Maruthamuthu, S; Berchmans, S; Palaniappan, A

2015-04-01

204

Riluzole: validation of stability-indicating HPLC, D1 and DD1 spectrophotometric assays.  

PubMed

A stability-indicating reversed-phase high-performance liquid chromatographic assay procedure has been developed and validated for riluzole in the presence of alkaline and oxidative degradation products. The liquid chromatographic separation was achieved and compared isocratically on C18 Zorbax ODS and Poroshell 120 EC-C18 columns by using a mobile phase containing methanol-water, pH = 3.10 (70:30, v/v), at a flow rate of 1 mL/min and ultraviolet detection at 264 nm. The method was linear over the concentration ranges of 20-200 µg/mL (r = 0.9997) and 10-200 µg/mL (r = 0.9995). The limit of detection and quantitation for the two columns were 2 and 6 µg/mL and 1 and 3 µg/mL, respectively. Moreover, spectrophotometric methods were applied for the determination of riluzole in the presence of its oxidative degradation products by using first derivative spectrophotometry at 252.5 and 275.0 nm. The method was linear over the concentration range of 1-20 µg/mL (r = 0.9995 and 0.9996) at the studied wavelengths, with limits of detection and quantitation of 0.1 and 0.3 µg/mL. In addition, the first derivative ratio spectrophotometry (DD1) method was applied for the determination of riluzole in the presence of its alkaline degradation product at 252.0, 278.5 and 306.3 nm by using 100 µg/mL of alkaline degraded riluzole as a divisor; riluzole was additionally determined in the presence of its hydrogen peroxide oxidative degradation products at 252.5, 275.0 and 305.0 nm by using 200 µg/mL of oxidative degraded riluzole as a divisor. The DD1 method was linear over the concentration range of 1-20 µg/mL (r = 0.9996, 0.9995 and 0.9996 for the alkaline degradation product at the three studied wavelengths, respectively; and r = 0.9995, 0.9996 and 0.9995 for the oxidative degradation product at the three studied wavelengths, respectively), with limits of detection and quantitation of 0.1 and 0.3 µg/mL for both alkaline and oxidative degradation products. The two studied chromatographic and spectrophotometric methods were comparable and display the required accuracy, selectivity, sensitivity and precision to assay riluzole in bulk and pharmaceutical dosage forms. Degradation products resulting from the stress studies did not interfere with the detection of riluzole, which indicates that these are stability-indicating assays. PMID:23744878

Saleh, Ola A; El-Azzouny, Aida A; Aboul-Enein, Hassan Y; Badawey, Amr M

2014-07-01

205

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

PubMed

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

Doomkaew, Athiporn; Prutthiwanasan, Brompoj; Suntornsuk, Leena

2015-01-01

206

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

PubMed Central

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

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

2011-01-01

207

Stability indicating methods for determination of Donepezil Hydrochloride according to ICH guidelines.  

PubMed

Stability indicating assays for determination of Donepezil Hydrochloride in presence of its oxidative degradate were developed and validated. The first three are spectrophotometric methods depending on using zero order (D(0)), first order (D(1)) and second order (D(2)) spectra. The absorbance was measured at 315 nm for (D(0)) while the amplitude was measured at 332.1nm for (D(1)) and 340 nm for (D(2)) using deionized water as a solvent. Donepezil Hydrochloride (I) can be determined in the presence of up to 70% of its oxidative degradate (II) using (D(0)), 80% using (D(1)) and 90% using (D(2)). The linearity range was found to be 8-56 microg ml(-1) for (D(0)), (D(1)) and (D(2)). These methods were applied for the analysis of I in both powder and tablet form. Also, a spectrofluorimetric method depending on measuring the native fluorescence of I in deionized water using lambda excitation 226 nm and lambda emission 391 nm is suggested. The linearity range was found to be 0.32-3.20 microg ml(-1) using this method, I was determined in the presence of up to 90% of II. The proposed method was applied for the analysis of I in tablet form as well as in human plasma. The last method depends on using TLC separation of I from its oxidative degradate II and I was then determined spectrodensitometrically. The mobile phase was methanol : chloroform : 25% ammonia (16 : 64 : 0.1 by volume). The linearity range was found to be 2-15 microg/spot. This method was applied to the analysis of I in both powder and tablet form using acetonitrile as a solvent. PMID:17015988

Abbas, Samah Sayed; Fayez, Yasmin Mohamed; Abdel Fattah, Laila El-Sayed

2006-10-01

208

Testing of conductivity/calcium and rubidium/strontium ratios as indicators of the chemical stability of a river: comparison with a biological indicator.  

PubMed

It is customary to detect pollution in a water flow by monitoring the increase of sensitive elements concentrations (NH4+, PO4(3-), NO3-...). However, concentrations are dependent on the flow rate and these compounds are not conservative, implying a concentration decrease downstream leading to false negative diagnosis of pollution impact. The use of elemental ratios of conservative compounds should diminish these pitfalls. We then thought of the chi/Ca (conductivity/calcium) and Rb/Sr (rubidium/strontium) ratios as water chemical stability indicators to clearly identify and discriminate point from diffuse pollutions. This hypothesis has been tested on 12 brooks located in the basin of Lake Geneva, during 2 hydrological years. The results were compared to the observed land use of the watershed and a biological indicator: the Pollution Sensitivity Index (PSI). The PSI is calculated from diatom taxonomy and evaluates biological quality with a grade ranging from 0 to 20 (bad to excellent). The main results of the research can be summarized as follows. The pollution signal is observable far downstream of the pollution site. Both chi/Ca and Rb/Sr ratios are water quality indicators expressing the stability of water chemistry. They can both be used to detect diffuse and point pollution impact. These indicators provide complementary information: chi/Ca variations increase in case of point pollution; Rb/Sr variations increase when diffuse pollutions occur. The results obtained with the indicators chi/Ca and Rb/Sr agree with biological indicator and observation of the land use. chi/Ca and Rb/Sr ratios represent important tools to identify and discriminate point source pollution from diffuse pollution. PMID:16477998

Nirel, P M V; Lazzarotto, J

2005-01-01

209

DNA damage induced p53 stabilization: no indication for an involvement of p53 phosphorylation  

Microsoft Academic Search

Abundance and activity of p53 are predominantly regulated posttranslationally. Structural disturbance in transcribed genes induced by radiation, e.g. DNA damage, or by transcriptional inhibitors cause p53 protein stabilization by a yet unknown mechanism. Using stable and transient transfections for the analysis of p53 mutant proteins, we have ruled out a role in stabilization by UV, gamma irradiation or actinomycin C

Christine Blattner; Edda Tobiasch; Margarethe Litfen; Hans J Rahmsdorf; Peter Herrlich

1999-01-01

210

Quantification of potential impurities by a stability indicating UV–HPLC method in niacinamide active pharmaceutical ingredient  

Microsoft Academic Search

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

Saji Thomas; Amber Bharati; Kalsang Tharpa; Ashutosh Agarwal

211

On the possibility of the space-dependence of the stability indicator (decay ratio) of a BWR  

E-print Network

On the possibility of the space-dependence of the stability indicator (decay ratio) of a BWR Christophe Demazie`re *, Imre Pa´zsit Department of Reactor Physics, Chalmers University of Technology, SE 2005 Abstract A model is proposed for the explanation of the space-dependence of the so-called decay

Pázsit, Imre

212

HPLC AND LCMS STUDIES ON STRESS DEGRADATION BEHAVIOR OF LEVOCETIRIZINE AND DEVELOPMENT OF A VALIDATED SPECIFIC STABILITY-INDICATING METHOD  

Microsoft Academic Search

The objective of the current investigation was to study the degradation behavior of levocetirizine under different ICH recommended stress conditions using HPLC and LC-MS and to establish a validated stability-indicating method. The drug was subjected to stress conditions of hydrolysis, photolysis, and thermal decomposition. Extensive degradation was found to occur in photolytic stress conditions. Mild degradation was observed in acidic,

Rahul P. Gunjal; G. Raju; A. Ramesh Babu; N. Mallikarjun; Nalini Shastri; R. Srinivas

2011-01-01

213

Validated stability-indicating methods for determination of cilostazol in the presence of its degradation products according to the ICH guidelines  

Microsoft Academic Search

Sensitive and selective stability-indicating assay methods (SIAMs) are suggested for the determination of cilostazol (CIL) in the presence of its acid, alkaline and oxidative degradation products. Developing SIAMs is necessary to carry out any stability study. Stress testing of CIL was performed according to the International Conference on Harmonization (ICH) guidelines in order to validate the stability-indicating power of the

Ahmad S. Fayed; Mostafa A. Shehata; Ahmed Ashour; Nagiba Y. Hassan; Soheir A. Weshahy

2007-01-01

214

Stability-indicating methods for determination of tiapride in pure form, pharmaceutical preparation, and human plasma.  

PubMed

Four different stability-indicating procedures are described for determination of tiapride in pure form, dosage form, and human plasma. Second derivative (D2), first derivative of ratio spectra (1DD), spectrofluorimetric, and high-performance column liquid chromatographic (LC) methods are proposed for determination of tiapride in presence of its acid-induced degradation products, namely 2-methoxy-5-(methylsulfonyl) benzoic acid and 2-diethylaminoethylamine. These approaches were successfully applied to quantify tiapride using the information included in the absorption, excitation, and emission spectra of the appropriate solutions. In the D2 method, Beer's law was obeyed in the concentration range of 1.5-9 microg/mL with a mean recovery of 99.94 +/- 1.38% at 253.4 nm using absolute ethanol as a solvent. In 1DD, which is based on the simultaneous use of the first derivative of ratio spectra and measurement at 245 nm in absolute ethanolic solution, Beer's law was obeyed over a concentration range of 1.5-9 microg/mL with mean recovery 99.64 +/- 1.08%. The spectrofluorimetric method is based on the determination of tiapride native fluorescence at 339 nm emission wavelength and 230 nm excitation wavelength using water-methanol (8 + 2, v/v). The calibration curve was linear over the range of 0.2-3 microg/mL with mean recovery of 99.66 +/- 1.46%. This method was also applied for determination of tiapride in human plasma. A reversed-phase LC method performed at ambient temperature was validated for determination of tiapride using methanol-deionized water-triethylamine (107 + 93 + 0.16, v/v/v) as the mobile phase. Sulpiride was used as an internal standard at a flow rate of 1 mL/min with ultraviolet detection at 214 nm. A linear relation was obtained over a concentration range of 2-30 microg/mL with mean recovery of 99.66 +/- 0.9%. Results were statistically analyzed and compared with those obtained by applying the reference method. They proved both accuracy and precision. PMID:18193732

Metwally, Fadia H; Abdelkawy, Mohammad; Abdelwahab, Nada S

2007-01-01

215

Systematic study of long-term stability of 3,4-dihydroxyphenylglycol in plasma for subsequent determination with liquid chromatography.  

PubMed

The effect of three storage temperature levels (i.e. +4, -20 and -80 degrees C) and time intervals from sampling (3, 6 and 9 months) on the degradation of 3,4-dihydroxyphenylglycol (DHPG) and norepinephrine (NE) was investigated in a systematic study. Extracted human plasma samples and acidified standard solutions were stored for long periods (up to 9 months) without the addition of any stabilizing agent. DHPG and NE values, determined using a ion-pair reversed-phase high-performance liquid chromatography method with electrochemical detection of coulometric type (IP-RP-HPLC-CD), remained constant over time in those plasma samples and standard solutions that had been stored at the lowest storing temperature (i.e. -80 degrees C). The expected degradation was observed at higher temperature levels. Plasma and standard DHPG degradation can, therefore, be prevented by storing samples at a lower temperature than previously suggested with no need to add any stabilizing agent. PMID:15018784

Venneri, Maria Grazia; Del Rio, Graziano

2004-04-01

216

School Effect Indices: Stability of One- and Two-Level Formulations.  

ERIC Educational Resources Information Center

This study evaluated the comparative stability and agreement of three approaches to calculating school effects given both student-level and school-level data. The approaches were hierarchical linear modeling (HLM), ordinary least squares (OLS), and weighted least squares (WLS). Analyses were conducted using data from the 1998 Maryland School…

Yen, Shu-Jing; Schafer, William D.; Rahman, Taslima

217

The enigma of double BSRs: indicators for changes in the hydrate stability field?  

Microsoft Academic Search

A classical bottom simulating reflector (BSR) and a presently unknown double BSR pattern are detectable in reflection seismic\\u000a profiles from the Storegga Slide area west of Norway. Pressure and temperature modeling schemes lead to the assumption that\\u000a the strong BSR marks the base of a hydrate stability zone with a typical methane gas composition of 99%. The upper double\\u000a BSR

J. Posewang; J. Mienert

1999-01-01

218

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

SciTech Connect

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

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

2013-07-01

219

APPLICATION OF A STABILITY-INDICATING TLC METHOD FOR THE QUANTITATIVE DETERMINATION OF DEXKETOPROFEN TROMETAMOL IN PHARMACEUTICAL DOSAGE FORMS  

Microsoft Academic Search

Objective: A sensitive, selective, precise and stability-indicating thin layer chromatographic method for analysis of Dexketoprofen trometamol, both as a bulk drug and in formulation, was developed and validated.Method: The method employed TLC aluminum plates precoated with silica gel 60F-254 as the stationary phase and the solvent system consisted of toluene:ethyl acetate:glacial acetic acid (6:2:0.2 v\\/v\\/v). This system was found to give

Vidhya K. Bhusari; Sunil R. Dhaneshwar

2011-01-01

220

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

Microsoft Academic Search

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

Nandini R. Pai; Deepnandan S. Dubhashi

2010-01-01

221

DEVELOPMENT AND VALIDATION OF TWO CHROMATOGRAPHIC STABILITY-INDICATING METHODS FOR DETERMINATION OF ROSUVASTATIN IN PURE FORM AND PHARMACEUTICAL PREPARATION  

Microsoft Academic Search

Two new, simple, sensitive and accurate stability-indication methods were developed for quantitative determination of rosuvastain in the presence of its degradation products in raw material. The first is a High-Performance Liquid Chromatography (HPLC) method in which separation was achieved on Phenomenex C18 column (250 mm, i.d. 4.6 mm, 5 µm) using acetonitrile: 0.5 % formic acid (50 + 50, v\\/v

Hasumati A. Raj; Sadhana J. Rajput; Jayant B. Dave; Chaggan N. Patel

222

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

E-print Network

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

Iglic, Ales

223

Persistency of bacterial indicators in biosolids stabilization with coal fly ash and lime.  

PubMed

Alkaline coal fly ash and lime were tested for their effectiveness in pathogen removal from biosolids at different time intervals and temperatures. Coal fly ash at 10 and 35% w/w was mixed with dewatered biosolids and then the ash-biosolids mixture was mixed separately with 0, 1.1, 2.2, 4.4, 8.5, 11, and 18% calcium oxide (w/w on a dry weight basis) with and without heating to 55 degrees C. Total bacteria, salmonella, and total coliforms were monitored at various time intervals. Both ash-biosolids mixtures with or without lime amendment had a significantly lower total bacterial population than the biosolids control, but the residual indigenous bacterial flora in the ash and lime stabilized biosolids still maintained a population of greater than 10(4) g(-1) dry biosolids. Alkaline-stabilized biosolids with a lime amendment rate greater than 8.5% could maintain pH greater than or equal to 12 for more than 2 hours, which effectively removed total coliforms and salmonella in the mixture. Heat treatment to 55 degrees C and a storage time of 14 days provided an added advantage resulting in a further reduction in pathogens for all treatments. It is recommended that 10% ash-biosolids mixture should be amended with a minimum of 8.5% lime on a dry weight basis for at least 2 hours to achieve acceptable levels of salmonella and total coliforms to ensure no pathogenic risk following land application. PMID:11765997

Wong, J W; Fang, M; Jiang, R

2001-01-01

224

Stability-indicating HPTLC method for quantitative estimation of silybin in bulk drug and pharmaceutical dosage form.  

PubMed

In the present study a novel stability-indicating high-performance thin-layer chromatography (HPTLC) method for quantitative determination of silybin in bulk drug and nanoemulsion formulation has been developed and validated on silica using solvent chloroform-acetone-formic acid (9 : 2 : 1 v/v/v) (R(f )of silybin 0.46 +/- 0.05) in the absorbance mode at 296 nm. The method showed a good linear relationship (r(2) +/- 0.999) in the concentration range 25-1500 ng per spot. It was found to be linear, accurate, precise, specific, robust and stability-indicating and can be applied for quality control and standardization of several multi-component hepatoprotective formulations as well as for stability testing of different dosage forms. The method proposed was also used to investigate the kinetics of acidic and alkaline degradation processes by quantification of drug at different temperature to calculate the activation energy and half-life for silymarin degradation. PMID:19816854

Parveen, Rabea; Ahmad, Sayeed; Baboota, Sanjula; Ali, Javed; Alka, Ahuja

2010-06-01

225

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

NASA Astrophysics Data System (ADS)

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

Leifeld, Jens; Heiling, Maria; Hajdas, Irka

2014-05-01

226

Development and validation of a stability indicating LC method for the assay and related substances determination of Exemestane, an aromatase inhibitor  

Microsoft Academic Search

A selective stability indicating HPLC method was developed and validated for quantification of impurities (process related and degradants) and assay determination of Exemestane. Stability indicating power of the method was established by forced degradation experiments and mass balance study. The chromatographic separation was achieved with Hypersil BDS-C-18 using gradient elution. The developed method is validated for parameters like accuracy, linearity,

R. Suresh Kumar; M. Narasimha Naidu; Kasa Srinivasulu; K. Raja Sekhar; M. Veerender; M. K. Srinivasu

2009-01-01

227

Stability-indicating spectrofluorimetric method for the assay of ziprasidone in capsules.  

PubMed

A simple, rapid and highly sensitive spectrofluorimetric method was developed for determination of ziprasidone hydrochloride (ZPS) in capsules. The method is based on measuring the native fluorescence of ZPS in acetate buffer of pH 4.5 at 398 nm after excitation at 315 nm. The fluorescence-concentration plot was rectilinear over the range of 0.05-0.80 ?g mL(-1) with a lower detection limit (LOD) of 6.0 ng mL(-1) and quantification limit (LOQ) of 20.0 ng mL(-1). The method was fully validated and successfully applied to the determination of ZPS in its capsules with average percentage recovery of 99.7 ± 1.4. The method was extended to stability study of ZPS. The drug was exposed to acidic, alkaline, oxidative and photolytic degradation according to ICH guidelines. Moreover, the method was utilized to investigate the kinetics of the alkaline, acidic and oxidative degradation of the drug. A proposal for the degradation pathways was postulated. PMID:21327537

Walash, Mohamed I; Belal, Fathalla; El-Enany, Nahed; Eid, Manal; El-Shaheny, Rania N

2011-07-01

228

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

PubMed

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

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

2013-11-01

229

A validated stability-indicating liquid chromatographic method for the determination of retapamulin in topical dosage form.  

PubMed

A sensitive, stability-indicating reversed-phase high-performance liquid chromatographic method is developed and validated for the quantitative determination of retapamulin in topical dosage form. The chromatographic separation is achieved by using a C18 column (XTerra RP 18 250 × 4.6 mm, 5 µm) at 30°C. The mobile phase comprises a mixture of 0.05M potassium dihydrogen phosphate buffer (pH 6.1), acetonitrile and methanol in the ratio of 35:50:15 (v/v/v). The flow rate is set at 1.0 mL/min and chromatograms are extracted at 243 nm using a photodiode array detector. The method is validated with respect to linearity, accuracy, precision, robustness and forced degradation studies, which further prove the stability-indicating supremacy of the method. During forced degradation studies, retapamulin is observed to be labile to oxidative and base hydrolysis stress and stable in thermal, photolytic and acid hydrolysis stress. The degradation products are well separated from the retapamulin peak, thus proving the stability-indicating superiority of the method. The method is found to be sensitive for retapamulin, with a detection limit of 25 ng/mL and a quantification limit of 80 ng/mL. The proposed method is found to be very sensitive and accurate for the determination of retapamulin in topical dosage form. The method is also demonstrated to be robust, because it is resistant to small variations of chromatographic variables such as pH, mobile phase composition, flow rate and column temperature. PMID:23510782

Nalwade, Santaji; Reddy, Vangala Ranga

2014-03-01

230

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

Microsoft Academic Search

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 (50mm×4.6mm, 1.8?m) column using mobile phase of methanol–0.01M ammonium acetate buffer, pH5.0 (80:20, v\\/v)

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

2011-01-01

231

Study of the Degradation Kinetics of Carvedilol by Use of a Validated Stability-Indicating LC Method  

Microsoft Academic Search

The objectives of this investigation were to establish a validated stability-indicating LC method for assay of carvedilol\\u000a and to study the degradation behaviour of the drug under different ICH-recommended stress conditions. Chromatographic separation\\u000a was achieved on a C18 column with 55:45 (%, v\\/v) acetonitrile–0.02 m phosphate buffer, pH 3.5, as mobile phase at a flow rate of 1.0 mL min?1; detection was by

Mohammad Rizwan; Mohammed Aqil; Adnan Azeem; Yasmin Sultana; Sushama Talegaonkar; Asgar Ali

2009-01-01

232

Development and Validation of a Stability-Indicating LC Method to Quantify Hydrochlorothiazide in Oral Suspension for Pediatric Use  

Microsoft Academic Search

A stability-indicating reversed-phase high-performance liquid chromatography (LC) method was developed and validated for the\\u000a determination of hydrochlorothiazide in an oral suspension. Isocratic chromatography was performed on a C18 column with 0.1 M sodium phosphate buffer pH 3.0\\/acetonitrile (70:30 v\\/v) as mobile phase, at a flow rate of 1.3 mL min?1, and UV detection at 254 nm. The method was linear (r\\u000a 2 = 0.9998), accurate (mean

Monika Piazzon Tagliari; Hellen Karine Stulzer; Fabio Seigi Murakami; Gislaine Kuminek; Bruno Valente; Paulo Renato Oliveira; Marcos Antonio Segatto Silva

2008-01-01

233

A Validated Stability-Indicating TLC Method for Determination of Forskolin in Crude Drug and Pharmaceutical Dosage Form  

Microsoft Academic Search

A simple, accurate, selective, precise, economical and stability-indicating high-performance thin-layer chromatographic method\\u000a for analysis of forskolin in crude drug and in pharmaceutical dosage form was developed and validated. The method was developed\\u000a on TLC aluminium plates precoated with silica gel 60F-254 using solvent system benzene:methanol (9:1, v\\/v), which gives compact spot of forskolin (R\\u000a \\u000a f\\u000a value 0.25 ± 0.02). Densitometric analysis of

Sayeed Ahmad; Mohd. Rizwan; Rabea Parveen; Mohd. Mujeeb; Mohd. Aquil

2008-01-01

234

Development and Validation of a Stability Indicating LC Method for the Determination of Faropenem in Pharmaceutical Formulations  

Microsoft Academic Search

A simple, selective and sensitive stability indicating LC method has been developed and validated for the determination of\\u000a faropenem in bulk drug and pharmaceutical formulations in the presence of degradation products. The separation was achieved\\u000a by using an isocratic mobile phase mixture of acetate buffer of pH 3.5 and methanol (65:35, v\\/v) and 250 mm × 4.6 mm I.D., 5 ?m particle size SGE make

Shobhana K. Menon; Jayesh G. Panchal; Ravindra V. Patel

2009-01-01

235

Stability-Indicating HPLC Method for Simultaneous Determination of Pantoprazole and Domperidone from their Combination Drug Product  

Microsoft Academic Search

A stability-indicating HPLC method has been developed and subsequently validated for the simultaneous determination of domperidone\\u000a and pantoprazole in commercial tablets. The proposed HPLC method utilizes Phenomenex® Gemini C18 column (150 mm × 4.6 mm i.d., 5 ?m) and mobile phase consisting of methanol-acetonitrile-20 mM dipotassium hydrogen phosphate\\u000a and phosphoric acid buffer pH 7.0 (20:33:47, v\\/v\\/v) at a flow rate of 1.19 mL min?1. Quantitation was achieved with

Sivakumar Thanikachalam; Manavalan Rajappan; Valliappan Kannappan

2008-01-01

236

Stability-Indicating HPTLC Method for Analysis of Moclobemide, and Use of the Method to Study Degradation Kinetics  

Microsoft Academic Search

A sensitive, selective, precise, and stability-indicating HPTLC method for analysis of moclobemide in the bulk drug and in\\u000a formulations has been established and validated. Aluminium TLC plates precoated with silica gel 60 F254 were used with benzene–methanol–40% ammonia 7:3:0.1 (v\\/v) as mobile phase. Densitometric analysis was performed in absorbance mode at 238 nm. Compact bands were obtained for moclobemide\\u000a (R\\u000a F

Shital S. Patel; Rajesh S. Keshalkar; Mandev B. Patel

2008-01-01

237

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

Microsoft Academic Search

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

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

2008-01-01

238

Development and Validation of a Stability-Indicating LC Method for Determination of Ebastine in Tablet and Syrup  

Microsoft Academic Search

A simple stability-indicating reversed-phase liquid chromatographic method with diode-array detection was developed and validated\\u000a for the quantitative determination of ebastine in tablets and syrup. The LC method was carried out on a C18 column with acetonitrile:phosphoric acid 0.1% pH 3.0 (55:45, v\\/v) as mobile phase, at a flow rate of 1.2 mL min?1. Ultraviolet detection of ebastine was at 254 nm. A linear

Marcela Z. Arend; Simone G. Cardoso; Felipe K. Hurtado; Aline Ravanello; Fibele A. Lanzanova; Clarice M. B. Rolim

2009-01-01

239

Development and validation of a stability indicating HPLC method for the analysis of lornoxicam in powder for injection.  

PubMed

A rapid, isocratic stability indicating high performance liquid chromatographic method was developed and validated for the estimation of lornoxicam in its powder for injection. The analysis was performed on a Shimadzu VP-ODS (4. 6 mm x 15 cm, 5 µm) column. The mobile phase consisted of sodium acetate (pH 5.8; 0.05 M) and methanol (45:55) flowed at 1.0 ml/min. Detection was carried out at 290 nm. The developed method had the good ability to separate lornoxicam well from the degradation products. The regression data showed good linear relationship at the concentration range of 4.04-20.20 ?/mL with r(2)=0.9999. Specificity, linearity, accuracy, precision and robustness of the method were evaluated to validate the proposed method. Stressed degradation studies were conducted to provide an indication of its stability indicating property. The limits of detection and quantitation were 9.70 and 33.94 ng /ml, respectively. Lornoxicam was found to be stable in the mobile phase in 24 h. The co-existed excipients had no interference with the analytical procedure. Additional peaks appeared in the chromatograms of five kinds of forced degraded samples (light, heat, acid, base and oxidation degradation). Mean recovery assessed at three levels was from 99. 7 to 100.3%, indicating the good accuracy of the method. Repeatability and inter-day RSD of the method was determined to be 0.38% and 0.81%, respectively. The HPLC method was demonstrated to be robust for intentional minor changes of ratio, pH change, salt concentration and column temperature. The method should be utilized as the routine analysis and quality control of lornoxicam in injectable formulation. PMID:22459464

Zhang, Jianjun; Li, Li; Gao, Yuan; Fan, Weiming

2012-04-01

240

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

PubMed

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

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

2011-10-01

241

Development and validation of a stability indicating capillary electrophoresis method for the determination of metformin hydrochloride in tablets.  

PubMed

A simple and a stability indicating capillary electrophoresis method was developed and validated for the analysis of metformin hydrochloride in tablet formulation. The method employed 40 mM citrate buffer at pH 6.7 as a background electrolyte with an applied voltage of 15 kV (positive polarity). The capillary used was of 68.5 cm length (60 cm to detector) and the detection wavelength was 230 nm. The method was validated in accordance with the ICH requirements, which involved accuracy, precision, linearity, selectivity and both limit of detection and limit of quantitation. The current method was linear over the concentration range of 0.2-2.0mg/ml of metformin hydrochloride. The method was precise as reflected by inter-day and intra-day relative standard deviation (RSD) of less than 2%. The limit of detection and limit of quantitation were 2.0 microg/ml and 8.0 microg/ml, respectively. The stability indicating capability of the method was established by enforced degradation studies combined with peak purity assessment using photodiode array detection. PMID:20395106

Hamdan, I I; Jaber, A K Bani; Abushoffa, A M

2010-12-15

242

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

PubMed Central

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

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

2011-01-01

243

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

PubMed Central

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

2014-01-01

244

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

NASA Astrophysics Data System (ADS)

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

Seifina, Elena; Titarchuk, Lev; Frontera, Filippo

245

A Stability-indicating HPLC Method for Assay of Lercanidipine Hydrochloride in Tablets and for Determining Content Uniformity  

PubMed Central

A simple, precise and accurate HPLC method has been developed and validated for assay of lercanidipine hydrochloride in tablets and for determination of content uniformity. An isocratic separation was achieved using a Chromasil YMC Pack C8, 150 × 4.6 mm i.d., 5µm particle size columns with a flow rate of 1 ml/min and using a UV detector to monitor the elute at 240 nm. The mobile phase consisted of 0.02 M ammonium dihydrogen phosphate buffer:methanol (35:65, v/v) with pH 3.5 adjusted with phosphoric acid. The method was validated for specificity, linearity, pre-cision, accuracy, robustness and solution stability. The specificity of the method was deter-mined by assessing interference from the placebo and by stress testing of the drug (forced degradation). The method was linear over the concentration range of 20-80 µg/ml (r2= 0.9992) with a limit of detection and quantitation of 0.1 and 0.3 µg/ml respectively. Intraday and interday system and method precision were determined and accuracy was between 99.3-101.9 %. The method was found to be robust and suitable for assay of lercanidipine hydrochloride in a tablet formulation and for determination of content uniformity. Degradation products resulting from the stress studies did not interfere with the detection of lercanidipine hydrochloride and the assay is thus stability-indicating. PMID:21188053

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

2010-01-01

246

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

PubMed Central

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

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

2012-01-01

247

A new strategy to stabilize oxytocin in aqueous solutions: I. The effects of divalent metal ions and citrate buffer.  

PubMed

In the current study, the effect of metal ions in combination with buffers (citrate, acetate, pH 4.5) on the stability of aqueous solutions of oxytocin was investigated. Both monovalent metal ions (Na(+) and K(+)) and divalent metal ions (Ca(2+), Mg(2+), and Zn(2+)) were tested all as chloride salts. The effect of combinations of buffers and metal ions on the stability of aqueous oxytocin solutions was determined by RP-HPLC and HP-SEC after 4 weeks of storage at either 4°C or 55°C. Addition of sodium or potassium ions to acetate- or citrate-buffered solutions did not increase stability, nor did the addition of divalent metal ions to acetate buffer. However, the stability of aqueous oxytocin in aqueous formulations was improved in the presence of 5 and 10 mM citrate buffer in combination with at least 2 mM CaCl(2), MgCl(2), or ZnCl(2) and depended on the divalent metal ion concentration. Isothermal titration calorimetric measurements were predictive for the stabilization effects observed during the stability study. Formulations in citrate buffer that had an improved stability displayed a strong interaction between oxytocin and Ca(2+), Mg(2+), or Zn(2+), while formulations in acetate buffer did not. In conclusion, our study shows that divalent metal ions in combination with citrate buffer strongly improved the stability of oxytocin in aqueous solutions. PMID:21448747

Avanti, Christina; Amorij, Jean-Pierre; Setyaningsih, Dewi; Hawe, Andrea; Jiskoot, Wim; Visser, Jan; Kedrov, Alexej; Driessen, Arnold J M; Hinrichs, Wouter L J; Frijlink, Henderik W

2011-06-01

248

Folding properties of cytosine monophosphate kinase from E. coli indicate stabilization through an additional insert in the NMP binding domain.  

PubMed

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

Beitlich, Thorsten; Lorenz, Thorsten; Reinstein, Jochen

2013-01-01

249

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

PubMed Central

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

Beitlich, Thorsten; Lorenz, Thorsten; Reinstein, Jochen

2013-01-01

250

Stability-Indicating Spectrofluorimetric Methods for the Determination of Metolazone and Xipamide in Their Tablets. Application to Content Uniformity Testing.  

PubMed

A highly sensitive, simple and rapid stability-indicating spectrofluorimetric method was developed for the determination of metolazone (MET) and xipamide (XPM) in their tablets. The proposed method is based on the measurement of the native fluorescence of MET in methanol at 437 nm after excitation at 238 nm and XPM in alkaline methanolic solution at 400 nm after excitation at 255 nm. The fluorescence-concentration plots were rectilinear over the range of 2.0- 20.0 ng/mL for MET and 0.2- 2.0 ?g/mL for XPM, with lower detection limits (LOD) of 0.35 ng/mL and 0.02 ?g/mL and a lower quantification limit (LOQ) of 1.05 ng/mL and 0.07 ?g/mL for MET and XPM, respectively. The method was successfully applied to the analysis of MET and XPM in their commercial tablets and the results were in good agreement with those obtained using the official and comparison methods, respectively. Furthermore, content uniformity testing of the studied pharmaceutical tablets was also conducted. The application of the proposed method was extended to stability studies of MET and XPM after exposure to different forced degradation conditions, such as acidic, alkaline, oxidative and photolytic degradation conditions, according to ICH Guidelines. Moreover, the method was utilized to investigate the kinetics of the alkaline, acidic and photolytic degradation of MET. The apparent first-order rate constants and half-life times were calculated. Proposals for the degradation pathways for both MET and XPM were postulated. PMID:24091803

Walash, M I; El-Enany, N; Eid, M I; Fathy, M E

2013-10-01

251

Comparing prediction power and stability of broadband and hyperspectral vegetation indices for estimation of green leaf area index and canopy chlorophyll density  

Microsoft Academic Search

Hyperspectral reflectance data representing a wide range of canopies were simulated using the combined PROSPECT+SAIL model. The simulations were used to study the stability of recently proposed vegetation indices (VIs) derived from adjacent narrowband spectral reflectance data across the visible (VIS) and near infrared (NIR) region of the electromagnetic spectrum. The prediction power of these indices with respect to green

N. h. Broge; E. Leblanc

2001-01-01

252

Quantification of Halobetasol Propionate and Its Impurities Present in Topical Dosage Forms by Stability-Indicating LC Method.  

PubMed

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

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

2015-01-01

253

New Stability-Indicating RP-UFLC Method for Determination of Trospium Chloride in Tablet Dosage Form  

PubMed Central

A simple, precise, and accurate isocratic RP-UFLC stability-indicating assay method has been developed to determine trospium chloride in tablet dosage form. Isocratic separation was achieved on an Enable-C18G (250 mm × 4.6 mm i.d., particle size 5 ?m) column at room temperature, the mobile phase consisted of acetonitrile:0.01M TBAHS (50:50, v/v) at a flow rate of 1.0 ml/min, the injection volume was 20 ?l, and PDA detection was carried out at 215 nm. 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 10–300 ?g/ml with the correlation coefficient being 0.999. The RSD for repeatability and intermediate precision was well below 2%. The mean recoveries were between 100.52–101.68% for trospium chloride. PMID:23264942

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

2012-01-01

254

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

PubMed Central

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 ?g 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

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

2014-01-01

255

Validating a stability indicating HPLC method for kinetic study of cetirizine degradation in acidic and oxidative conditions.  

PubMed

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

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

2013-01-01

256

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

PubMed

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

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

2009-01-01

257

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

PubMed

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

Patel, Apexa; Patwari, Arpit; Suhagia, Bhanubhai

2014-01-01

258

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

PubMed

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

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

2011-01-01

259

Multivariate development and validation of a stability-indicating HPLC method for the determination of glimepiride in tablets.  

PubMed

This paper describes the multivariate development of a stability-indicating HPLC method for the quantification of glimepiride in pharmaceutical tablets. Full factorial design, Doehlert design, and response-surface methodology were used in conjunction with the desirability function approach. This procedure allowed the adequate separation of glimepiride from all degradant peaks in a short analysis time (about 9 min). This HPLC method uses potassium phosphate buffer (pH 6.5; 27.5 mmol/L)-methanol (34 + 66, v/v) mobile phase at a flow rate of 1.0 mL/min and UV detection at 228 nm. A Waters Symmetry C18 column (250 x 4.6 mm, 5.0 pm) at controlled room temperature (25 degrees C) was used as the stationary phase. The method was validated according to International Conference on Harmonization guidelines and demonstrated linearity from 2 to 40 mg/L glimepiride, selectivity, precision, accuracy, and robustness. The LOD and LOQ were 0.315 and 1.050 mg/L, respectively. The multivariate strategy adopted in this work can be successfully applied in routine laboratories because of its fast optimization without the additional cost of columns or equipment. PMID:24282932

Bonfilio, Rudy; Peres, Carolina; Salgado, Hérida R N; De Araújo, Magali B; Tarley, César R T

2013-01-01

260

Development and validation of stability indicating HPLC and HPTLC methods for determination of sulpiride and mebeverine hydrochloride in combination.  

PubMed

Validated sensitive and highly selective stability indicating methods are adopted for simultaneous quantitative determination of sulpiride and mebeverine hydrochloride in presence of their reported impurities and hydrolytic degradates whether in pure forms or in pharmaceutical formulation. The first method is High Performance Liquid Chromatography, where the mixture of sulpiride and mebeverine hydrochloride together with the reported interferents plus metopimazine as internal standard are separated on a reversed phase cyano column (5 microm ps, 250 mm x 4.6 id) using acetonitrile: water (70:30 v/v) adjusted to pH = 7 as a mobile phase. The drugs were detected at 221 nm over a concentration range of 5-40 microg ml(-1) and 5-60 microg ml(-1) with mean percentage recoveries 99.75% (S.D. 0.910) and 99.99% (S.D. 0.450) for sulpiride and mebeverine hydrochloride respectively. The second method is High Performance Thin Layer Chromatography, where sulpiride and mebeverine hydrochloride are separated on silica gel HPTLC F(254) plates using absolute ethanol:methylene chloride:triethyl amine (7:3:0.2 by volume) as mobile phase and scanning of the separated bands at 221 nm over a concentration range of 0.4-1.4 and 0.2-1.6 microg band(-1) with mean percentage recoveries 101.01% (S.D. 1.991) and 100.40% (S.D. 1.868) for sulpiride and mebeverine hydrochloride respectively. PMID:20538381

Naguib, Ibrahim A; Abdelkawy, Mohammed

2010-09-01

261

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

PubMed Central

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

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

2013-01-01

262

Development and validation of a stability indicating HPLC method for simultaneous determination of four novel fluoroquinolone dimers as potential antibacterial agents  

Microsoft Academic Search

A series of novel 6-fluoro1,4-dihydro-4-oxo-3-quinoline carboxylic acid dimers were synthesized as potential antibacterial agents from commercially available substituted fluorobenzoic acids. A stability indicating HPLC method was developed to determine these novel fluoroquinolone dimers using a systematic method development approach. Samples were subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal degradation; and analyzed to demonstrate the specificity and stability

Muzaffar Khan; C. Naveen Kumar Reddy; G. Ravindra; K. V. S. R. Krishna Reddy; P. K. Dubey

263

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

PubMed

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 ?m) 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

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

2014-04-01

264

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

PubMed

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

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

2007-11-01

265

Validated stability-indicating methods for the determination of nizatidine in the presence of its sulfoxide derivative.  

PubMed

Four new selective, precise, and accurate methods are described for the determination of nizatidine (NIZ) in the presence of its sulfoxide derivative in both the raw material and pharmaceutical preparations. Method A is based on zero-order (0D), first-derivative (1D), and second-derivative (2D) spectrophotometric measurement of NIZ in aqueous solution at the zero-crossing point of its sulfoxide derivative (at 314, 295-334, and 318-348 nm, respectively). Method B is a 1DD spectrophotometric method based on the simultaneous use of the first derivative of the ratio spectra and the measurement of peak amplitude at 297 nm. Method C uses a solvent-induced derivative-difference spectrophotometry with deltaD1 measurement from peak to peak at 315-345 nm. Method D involves quantitative densitometric evaluation of a mixture of the drug and its sulfoxide derivative after separation by high-performance thin-layer chromatography on silica gel plates with chloroform-methanol (9 + 1, v/v) as the mobile phase; Rf values for NIZ and its sulfoxide derivative were 0.4 and 0.2, respectively. The spot was scanned at 254 nm. The first-derivative spectrophotometric method was used to investigate the kinetics of the hydrogen peroxide degradation process at different temperatures. The apparent pseudo-first-order rate constant, half-life, and activation energy were calculated. The results obtained by the proposed methods were analyzed statistically and compared with those obtained by the official method. These methods are suitable as stability-indicating for the determination of NIZ in the presence of its oxidation-induced degradation product (sulfoxide derivative) either in the bulk powder or in pharmaceutical preparations. PMID:18376588

Youssef, Rasha M

2008-01-01

266

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

PubMed

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

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

2015-02-01

267

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

268

A Simple RP-HPLC Method for Quantitation of Itopride HCl in Tablet Dosage Form.  

PubMed

An isocratic reversed phase high-performance liquid chromatographic method with ultraviolet detection at 220 nm has been developed for the quantification of itopride hydrochloride in tablet dosage form. The quantification was carried out using C(8) column (250 mm × 4.6 mm), 5-?m particle size SS column. The mobile phase comprised of two solvents (Solvent A: buffer 1.4 mL ortho-phosphoric acid adjusted to pH 3.0 with triethyl amine and Solvent B: acetonitrile). The ratio of Solvent A: Solvent B was 75:25 v/v. The flow rate was 1.0 mL (-1)with UV detection at 220 nm. The method has been validated and proved to be robust. The calibration curve was linear in the concentration range of 80-120% with coefficient of correlation 0.9995. The percentage recovery for itopride HCl was 100.01%. The proposed method was validated for its selectivity, linearity, accuracy, and precision. The method was found to be suitable for the quality control of itopride HCl in tablet dosage formulation. PMID:21264104

Thiruvengada, Rajan Vs; Mohamed, Saleem Ts; Ramkanth, S; Alagusundaram, M; Ganaprakash, K; Madhusudhana, Chetty C

2010-10-01

269

A Simple RP-HPLC Method for Quantitation of Itopride HCl in Tablet Dosage Form  

PubMed Central

An isocratic reversed phase high-performance liquid chromatographic method with ultraviolet detection at 220 nm has been developed for the quantification of itopride hydrochloride in tablet dosage form. The quantification was carried out using C8 column (250 mm × 4.6 mm), 5-?m particle size SS column. The mobile phase comprised of two solvents (Solvent A: buffer 1.4 mL ortho-phosphoric acid adjusted to pH 3.0 with triethyl amine and Solvent B: acetonitrile). The ratio of Solvent A: Solvent B was 75:25 v/v. The flow rate was 1.0 mL -1with UV detection at 220 nm. The method has been validated and proved to be robust. The calibration curve was linear in the concentration range of 80-120% with coefficient of correlation 0.9995. The percentage recovery for itopride HCl was 100.01%. The proposed method was validated for its selectivity, linearity, accuracy, and precision. The method was found to be suitable for the quality control of itopride HCl in tablet dosage formulation. PMID:21264104

Thiruvengada, Rajan VS; Mohamed, Saleem TS; Ramkanth, S; Alagusundaram, M; Ganaprakash, K; Madhusudhana, Chetty C

2010-01-01

270

RP-HPLC Method Development and Its Validation for Quantitative Determination of Rimonabant in Human Plasma  

PubMed Central

A simple, accurate, and precise HPLC method was developed and validated for determination of rimonabant in human plasma. Following liquid-liquid extraction, chromatographic separation was accomplished using C18 column with mobile phase consisting of acetonitrile?:?water (90?:?10, v/v), drug was detected at 260?nm using UVdetector. The LOD and LOQ were 3.0 and 10.0??g/L, respectively. The method is linear in the interval 50.0–1000.0??g/L. The average extraction recovery of drug from plasma was found to be 92.2%. The percent CV of the method was found to be less than 10.8%, and accuracy was found between 94.5 and 106.7%. The assay may be applied to a pharmacokinetic and bioequivalence study of rimonabant. PMID:22619744

Bankey, Shravan; Tapadiya, Ganesh; Lamale, Jasvant; Jain, Deepti; Saboo, Shweta; Khadabadi, S. S.

2012-01-01

271

Simultaneous estimation of metformin hydrochloride, pioglitazone hydrochloride, and glimepiride by RP-HPLC in tablet formulation.  

PubMed

A simple, precise, rapid, and reproducible reversed-phase high-performance liquid chromatography method is developed for the simultaneous estimation of metformin hydrochloride (MET), pioglitazone hydrochloride (PIO), and glimepiride (GLP) present in multicomponent dosage forms. Chromatography is carried out isocratically at 25 degrees C +/- 0.5 degrees C on an Inertsil-ODS-3 (C-18) Column (250 x 4.60 mm, 5 microm) with a mobile phase composed of methanol-phosphate buffer (pH 4.3) in the ratio of 75:25 v/v at a flow rate of 1 mL/min. Detection is carried out using a UV-PDA detector at 258 nm. Parameters such as linearity, precision, accuracy, recovery, specificity, and ruggedness are studied as reported in the International Conference on Harmonization guidelines. The retention times for MET, PIO, and GLP are 2.66 + 0.5 min, 7.12 + 0.5 min, and 10.17 + 0.5 min, respectively. The linearity range and percentage recoveries for MET, PIO, and GLP are 10-5000, 10-150, and 1-10 microg/mL and 100.4%, 100.06%, and 100.2%, respectively. The correlation coefficients for all components are close to 1. The relative standard deviations for three replicate measurements in three concentrations of samples in tablets are always less than 2%. PMID:18647470

Jain, Deepti; Jain, Surendra; Jain, Deepak; Amin, Maulik

2008-07-01

272

RAPID RP HPLC METHOD FOR QUANTITATIVE DETERMINATION OF LORNOXICAM IN TABLETS  

PubMed Central

The objective of the study was to develop a simple, rapid, specific and precise reverse phase high performance liquid chromatographic method for the determination of lornoxicam in bulk and pharmaceutical preparations. Chromatographic separation of the drug was performed on a eclipse C18 column (150 mm × 4.6 mm, 5 ?m) as stationary phase and mobile phase used is methanol: 0.1% formic acid in water (80:20 v/v), with a flow rate of 0.8 mL min-1 and UV detection at 381 nm. The proposed method was validated for linearity, accuracy, precision, limit of detection (LOD) and limit of quantitation (LOQ). Linearity, accuracy and precision were found to be acceptable over the ranges of 0.5-20 ?g/ml. It can be conveniently adopted for routine quality control analysis of lornoxicam. PMID:24825976

Attimarad, Mahesh

2010-01-01

273

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

PubMed Central

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.

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

2015-01-01

274

Influence of stationary phase properties on the separation of ionic liquid cations by RP-HPLC.  

PubMed

Different types of columns with specific structural properties were used for the separation of mixtures of ionic liquid cations. Two of them were home-made packings and the other two were commercial stationary phases. One of the home-made packings contained cholesterol ligands bonded chemically to silica (SG-CHOL) whereas the other one was a mixed stationary phase (SG-MIX) with cyanopropyl, aminopropyl, phenyl, octyl, and octadecyl ligands. RP-18e Innovation ChromolithTM Performance and Macrosphere 300 C4 packings were also used. A comparison of the separation possibilities offered by these columns for the substances in question revealed significant differences in performance. Packings containing surface-bonded functional groups that are able to undergo protonation are not suitable for separation of such compounds under the given analysis conditions (pH = 4). The best results were obtained for two alkyl stationary phases: butyl and octadecyl. Cluster analysis has also been performed for comparison of the ionic liquid cation properties. PMID:16830726

Buszewski, Bogus?aw; Kowalska, Sylwia; Stepnowski, Piotr

2006-05-01

275

RP-HPLC determination of paraoxonase 3 activity in human blood serum  

Microsoft Academic Search

The aim of the present work was to establish conditions for paraoxonase 3 (PON3) activity determination in human blood serum with simvastatin (SV) as a substrate. The activity of PON3 is considered as a good early predictor of susceptibility to premature atherosclerosis as well as of statin therapy effectiveness. The method used quantifies the SV and ?,?-dihydroxyacid simvastatin (SVA) liberated

Zofia Suchocka; Joanna Swatowska; Jan Pachecka; Piotr Suchocki

2006-01-01

276

Validation and Method Development of Tadalafil in Bulk and Tablet Dosage Form by RP-HPLC.  

PubMed

A novel, precise, rapid and sensitive reverse phase high performance liquid chromatographic method has been developed for the validated estimation of Tadalafil in bulk and tablet dosage form. The separation was achieved on Agilent Eclipse XDB C18 column (150?mm×4.6?mm, 5?µ) using a mobile phase that consists of the buffer (potassium dihydrogen orthophosphate) and acetonitrile in the ration of 50:50?V/V, pH 6 was adjusted with orthophosphoric acid. The flow rate was maintained at 1.2?ml/min and the detection wavelength was 285?nm. The method was validated for linearity, specificity, sensitivity as per ICH guidelines. The retention time was found to be 3.181 for Tadalafil. The calibration curve was linear over the concentration range of 10-150?µg/ml. The % RSD was satisfactory which showed the method found to be reliable. The high percentage recovery confirmed the suitability of the method for estimation of Tadalafil in pharmaceutical dosage form. The developed method could be applicable for routine analysis of Tadalafil in bulk and tablet dosage form. PMID:24782284

Bojanapu, A; Subramaniam, A T; Munusamy, J; Dhanapal, K; Chennakesavalu, J; Sellappan, M; Jayaprakash, V

2015-02-01

277

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

PubMed Central

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 ?m 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 ?g/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

Seerapu, Sunitha; Srinivasan, B. P.

2010-01-01

278

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

PubMed

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

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

2014-04-01

279

Simultaneous RP-HPLC and HPTLC Estimation of Fluoxetine Hydrochloride and Olanzapine in Tablet Dosage Forms  

PubMed Central

A binary mixture of fluoxetine HCl and olanzapine was determined by two different methods. The first method involved determination of fluoxetine HCl and olanzapine using reversed-phase liquid chromatography using acetonitrile:methanol:0.032 M ammonium acetate buffer (45:05:50, v/v/v) as the mobile phase at a flow rate of 1.5 ml/min. Quantitation was achieved with ultraviolet detection at 235 nm over concentration ranges of 0.2-4 and 0.1-2 ?g/ml; mean accuracies were 101.16±0.59 and 99.79±0.56% for fluoxetine HCL and olanzapine, respectively. The second method was based on the high performance thin layer chromatography separation of the two drugs followed by densitometric measurements of their spots at 235 nm. The separation was carried out on Merck TLC aluminium sheets of silica gel 60 F254 using acetone:methanol:triethyleamine (5:3:0.5, v/v/v), as mobile phase. The linearity was found to be in the range of 300–1000 and 150–500 ng/spot; mean accuracies were 100.95±0.52 and 99.31±0.51% for fluoxetine HCl and olanzapine, respectively. The method was successively applied to tablets because no chromatographic interferences from the tablet excipients were found. The methods retained their accuracy and precision when the standard addition technique was applied. The results obtained by applying the proposed methods were statistically analyzed. PMID:20502563

Patel, Sejal; Patel, N. J.

2009-01-01

280

A new RP-HPLC method for analysis of mebeverine hydrochloride in raw materials and tablets.  

PubMed

A simple, sensitive, selective, reliable, least time consuming and rapid high-performance liquid chromatographic method for the determination and quantification of mebeverine hydrochloride using hyoscine butylbromide as internal standard has been developed. The chromatographic system consisted of a Shimadzu LC-10 AT VP pump, SPD-10 AV VP UV visible detector, and a CBM-102 Bus Module integrator. Separation was achieved on the micro Bondapak 125 a C18 10microm column at room temperature. The samples were introduced through an injector valve with a 10 microl sample loop. Acetonitrile-water (1:1 v/v) was used as mobile phase, with flow rate 1.7 ml/minutes. pH was adjusted to 2.9 with phosphoric acid. U.V detection was performed at 205 nm. The results obtained showed a good agreement with the declared content. Recovery values of mebeverine hydrochloride were from 99.80% to 100.13%. The proposed method is rapid, accurate, and selective and may be used for the quantitative analysis of mebeverine hydrochloride. The method was found to be specific, accurate, precise and reliable for the determination and quantification of mebeverine hydrochloride in form of raw materials, in bulk drugs and formulation. It was possible to determine all of them in the concentration range of 5-30 nano grams. The detection limit of mebeverine hydrochloride was 0.4-nano gram. PMID:16431391

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

2005-04-01

281

A validated stability-indicating LC method for acetazolamide in the presence of degradation products and its process-related impurities  

Microsoft Academic Search

The objective of the current study was to develop a validated, specific and stability-indicating reverse phase liquid chromatographic method for the quantitative determination of acetazolamide and its related substances. The determination was done for an active pharmaceutical ingredient, its pharmaceutical dosage form in the presence of degradation products, and its process-related impurities. The drug was subjected to stress conditions of

Prabha Srinivasu; Devarakonda V. SubbaRao; Raju V. K. Vegesna; K. Sudhakar Babu

2010-01-01

282

THE SELECTION OF AN ION PAIRING REAGENT FOR DEVELOPING AND VALIDATING A STABILITY-INDICATING HPLC METHOD FOR CROMOLYN SODIUM AND ITS KNOWN IMPURITIES  

Microsoft Academic Search

A robust, stability-indicating isocratic HPLC method for the quantitation of cromolyn sodium and its related substances was developed and validated. The two known synthetic impurities likely to be present in cromolyn drug substance, designated as impurity 1 and impurity 2, are non-ionic compounds while cromolyn is a weak acid. The described HPLC method exploits the additional selectivity offered by using

M. Barnes; R. Mansfield; S. Thatcher

2002-01-01

283

Development and validation of a stability indicating HPLC method for determination of lisinopril, lisinopril degradation product and parabens in the lisinopril extemporaneous formulation  

Microsoft Academic Search

The purpose of the research described herein was to develop and validate a stability-indicating HPLC method for lisinopril, lisinopril degradation product (DKP), methyl paraben and propyl paraben in a lisinopril extemporaneous formulation. The method developed in this report is selective for the components listed above, in the presence of the complex and chromatographically rich matrix presented by the Bicitra® and

Christopher A. Beasley; Jessica Shaw; Zack Zhao; Robert A. Reed

2005-01-01

284

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

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

285

Development and validation of three stability-indicating methods for determination of bisacodyl in pure form and pharmaceutical preparations.  

PubMed

Three new, simple, sensitive, and accurate stability-indicating methods were developed for quantitative determination of bisacodyl in the presence of its degradation products, monoacetyl bisacodyl (I) and desacetyl bisacodyl (II), in enteric coated tablets, suppositories, and raw material. The first is a spectrodensitometric method in which the drug is separated from I and II on silica gel plates using chloroform-acetone (9 + 1, v/v) as the mobile phase with ultraviolet detection of the separated bands at 223 nm over a concentration range of 0.2-1.4 microg/band for bisacodyl with mean recovery 100.35 +/- 1.923%. The second method is fourth derivative D4 spectrophotometry, which allows determination of bisacodyl in the presence of its degradation products in raw material at 223 nm using acetonitrile as the solvent with adherence to Beer's law over the concentration range 2-18 microg/mL with mean recovery 99.77+/-1.056%. In the third method, the spectrophotometric data of bisacodyl, I, and II using absolute ethanol as solvent were processed by 3 chemometric techniques: classical least-squares, principal component regression, and partial least-squares. A training set consisting of 15 mixtures containing different ratios of bisacodyl, I, and II was used for construction of the 3 models. A validation set consisting of 6 mixtures was used to validate the prediction ability of the suggested models. The 3 chemometric methods were applicable over a concentration range between 2-14microg/mL for bisacodyl with mean recovery of 99.97+/-0.865, 100.01 +/- 0.749, and 99.97 +/- 0.616% for the 3 models, respectively. The proposed methods were checked using laboratory-prepared mixtures and were successfully applied to the analysis of raw material and pharmaceutical formulations containing bisacodyl, except for the second method that applies only for raw material. The validity of the suggested procedures was further assessed by applying the standard addition technique; the recoveries obtained were in accordance with those given by the reference method. PMID:17373442

Metwally, Fadia H; Abdelkawy, Mohammed; Naguib, Ibrahim A

2007-01-01

286

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

Microsoft Academic Search

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

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

2008-01-01

287

Validation of a Stability-Indicating LC Method for Assay of Ezetimibe in Tablets and for Determination of Content Uniformity  

Microsoft Academic Search

A simple, precise, and accurate HPLC method has been developed and validated for assay of ezetimibe in tablets and for determination\\u000a of content uniformity. Reversed-phase liquid chromatographic separation was achieved by use of phosphoric acid (0.1%, v\\/v)–acetonitrile 50:50 (v\\/v) as mobile phase. The method was validated for specificity, linearity, precision, accuracy, robustness, and solution stability.\\u000a The specificity of the method

Ashish S. Doshi; Pankaj K. Kachhadia; Hemendra S. Joshi

2008-01-01

288

A Fast, Stability-Indicating, and Validated Liquid Chromatography Method for the Purity Control of Lercanidipine Hydrochloride in Tablet Dosage Form  

PubMed Central

A robust, sensitive, and stability-indicating rapid resolution liquid chromatography method for the simultaneous determination of process impurities and degradation products of lercanidipine hydrochloride in pharmaceutical dosage form was developed and validated. The chromatographic separation was performed on the Zorbax SB C18 [(50 × 4.6) mm] 1.8 ?m column, using gradient elution of a potassium dihydrogen phosphate buffer (pH 3.5, 0.01 M) and acetonitrile. The flow rate was 1.0 ml/min and UV detection was performed at 220 nm. The method was further evaluated for its stability-indicating capability by hydrolytic, oxidative, thermal, thermal with moisture, and photolytic degradation studies. All acceptance criteria of the International Conference on Harmonization guidelines for validation were covered in the method validation. This method can be used for purity control during manufacture and real time stability studies. A shorter run time of 10 minutes and good solution stability for at least 48 hours allowed the quantification of more than 50 samples per day with comparatively lower costs than existing methods. PMID:24959405

Mehta, Saumil; Singh, Sukhdev; Chikhalia, Kishor

2014-01-01

289

A VALIDATED STABILITY INDICATING HPTLC METHOD FOR SIMULTANEOUS ESTIMATION OF CEFPODOXIME PROXETIL AND POTASSIUM CLAVULANATE IN BULK AND TABLET DOSAGE FORM  

Microsoft Academic Search

Cefpodoxime proxetil (Cef) and Potassium clavulanate (Pot.clav.) are used in the treatment of acute otitis media, typhoid fever, pharyngitis and tonsillitis. A simple, selective and stability indicating HPTLC method has been established for the simultaneous analysis of Cef and Pot.clav. in pharmaceutical formulations. The method uses aluminum-backed silica gel 60F254 HPTLC plates as stationary phase with toluene:methanol:chloroform:acetonitrile [4:3:2:1.5 (v\\/v\\/v\\/v)] as

A. B. Thomas; S. B. Dighe; R. K. Nanda; L. P. Kothapalli; S. N. Jagdale; A. D. Deshpande

2010-01-01

290

Validation of HPLC stability-indicating method for Vitamin C in semisolid pharmaceutical\\/cosmetic preparations with glutathione and sodium metabisulfite, as antioxidants  

Microsoft Academic Search

HPLC stability-indicating method was validated for Vitamin C (ascorbic acid) in semisolid pharmaceutical\\/cosmetic formulations containing glutathione and sodium metabisulfite, as antioxidants. The described procedure included a reliable, precise, accurate and specific method determination employing a 250mm×4.6mm C18 column, 0.2% metaphosphoric acid\\/methanol\\/acetonitrile (90:8:2, v\\/v\\/v) as the mobile phase and detection at 254nm. Nicotinic and ascorbic acids were employed as standards, both

Adriana M. Maia; André Rolim Baby; Wilson J. Yasaka; Eunice Suenaga; Telma M. Kaneko; Maria Valéria R. Velasco

2007-01-01

291

ICH guidance in practice: Validated stability-indicating HPLC method for simultaneous determination of ampicillin and cloxacillin in combination drug products  

Microsoft Academic Search

Ampicillin and cloxacillin were degraded together under different stress test conditions prescribed by International Conference on Harmonization. The samples so generated were used to develop a stability-indicating high performance liquid chromatographic (HPLC) method for the two drugs. The drugs were well separated from degradation products using a reversed-phase (C-18) column and a mobile phase comprising of acetonitrile:phosphate buffer (pH 5.0),

Vijay Kumar; Hemant Bhutani; Saranjit Singh

2007-01-01

292

Direct stability-indicating method development and validation for analysis of etidronate disodium using a mixed-mode column and charged aerosol detector  

Microsoft Academic Search

This paper describes the development and validation of a rapid, direct, and stability-indicating method for analysis of etidronate, a bisphosphonate compound without a UV chromophore. A mixed-mode column was used to separate etidronate from its impurities in an 8-min gradient method and a charged aerosol detector (CAD) was used for detection. The developed HPLC method was validated with respect to

Xiao-Keng Liu; Jiang B. Fang; Nina Cauchon; Pengzu Zhou

2008-01-01

293

DEVELOPMENT AND VALIDATION OF A STABILITY-INDICATING LC METHOD FOR THE DETERMINATION OF DOMPERIDONE, SORBIC ACID, AND PROPYLPARABEN IN PHARMACEUTICAL FORMULATIONS  

Microsoft Academic Search

A simple, selective, and sensitive stability-indicating LC method has been developed and validated for the simultaneous determination of sorbic acid, propylparaben, and domperidone in pharmaceutical oral suspension formulations. The separations was achieved on a Lichrosorb C8, 150 mm × 4.6 mm and 5 ?m column with detection of 280 nm using an isocratic mobile phase mixture of phosphate buffer (0.05 M) and methanol (40:60 v\\/v) at flow rate

Ghulam A. Shabir

2010-01-01

294

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

Microsoft Academic Search

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

B. Aksoy; ?. Küçükgüzel; S. Rollas

2007-01-01

295

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

NASA Technical Reports Server (NTRS)

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

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

2014-01-01

296

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

PubMed

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

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

2014-01-01

297

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

ERIC Educational Resources Information Center

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…

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

2006-01-01

298

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

PubMed

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

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

2011-01-01

299

Stability-indicating method for the determination of clorazepate dipotassium-I. Via its final degradation products.  

PubMed

A sensitive spectrophotometric procedure is described for the determination of 1,4-benzodiazepine (clorazepate dipotassium) in the presence of its degradation products. The procedure is based on acid hydrolysis of clorazepate dipotassium to yield its final degradation products viz., 2-amino-5-chlorobenzophenone and glycine. The amino-chlorobenzophrenone is extracted from the neutralized hydrolysate with diethyl ether, the extract is evaporated, the residue is dissolved in methanol and its absorbance measured at about 240 nm or 380 nm. Glycine, left in the aqueous layer after etherial extraction of aminochlorobenzophenone, is treated with ninhydrin reagent in the presence of pyridine and the bluish violet colour formed is measured at about 560 nm. The suggested procedures determine 20-100 mg of clorazepate dipotassium via its degradation products aminochlorobenzophenone and glycine with mean accuracies of 100.0 +/- 0.5% at 560 nm, 100.2 +/- 0.6% at 380 nm and 99.8 +/- 0.5%. The suggested procedures are suitable for stability-testing of clorazepate dipotassium in bulk powder and in pharmaceutical preparations. PMID:18965571

El-Bardicy, M G; Bebawy, L I; Amer, M M

1992-12-01

300

COMPARATIVE STUDY OF FORCED DEGRADATION BEHAVIOR OF PRASUGREL BY UPLC AND HPLC AND THE DEVELOPMENT OF VALIDATED STABILITY INDICATING ASSAY METHOD  

Microsoft Academic Search

A novel stability-indicating ultra-performance liquid chromatographic (UPLC) assay method was developed and validated for prasugrel and its degradation products. The UPLC separation was performed on Acquity® UPLC BEH C18 column (1.7 µm, 2.1 mm × 150 mm) using isocratic mode (acetonitrile:water, 80:20 v\\/v) at flow rate of 0.1 mL\\/min and the high performance liquid chromatography (HPLC) separation was achieved on Phenomenex® C8 column using isocratic mode

Kapendra Sahu; C. Karthikeyan; N. S. Hari Narayana Moorthy; Piyush Trivedi

2011-01-01

301

Development and Validation of a Stability-Indicating LC Method for Simultaneous Analysis of Aceclofenac and Paracetamol in Conventional Tablets and in Microsphere Formulations  

Microsoft Academic Search

A stability-indicating reversed-phase LC method for analysis of aceclofenac and paracetamol in tablets and in microsphere\\u000a formulations has been developed and validated. The mobile phase was 80:20 (v\\/v) methanol–phosphate buffer (10 mM at pH 2.5 ± 0.02). UV detection was at 276 nm. The method was linear over the concentration\\u000a ranges 16–24 and 80–120 ?g mL?1 for aceclofenac and paracetamol, respectively, with recovery in the range 100.9–102.22%.

Shahid Jamil; Sushma Talegaonkar; Roop K. Khar; Kanchan Kohli

2008-01-01

302

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

PubMed Central

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

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

2014-01-01

303

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

PubMed

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

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

2014-01-01

304

Is there any association between imidapril hydrochloride stability profile under dry air conditions and cancer initiation?  

PubMed

Stability study for imidapril hydrochloride (IMD) was performed under stress conditions of increased temperature (T=373 K) and decreased relative air humidity (RH=0%) in order to obtain and identify its degradation product. The degradation sample stored for 15 days under the above environmental conditions was analyzed by LC-MS technique and it was found that the only degradation impurity formed in the course of the investigated drug degradation was IMD diketopiperazine derivative (DKP) which was produced by dehydration and intramolecular cyclization. The kinetics of its formation was analyzed by a revalidated RP-HPLC method and the kinetic model of this reaction was established. It was concluded that the DKP formation follows Prout-Tompkins kinetics with the rate constant k±?k=2.034±0.157×10(-6) [s(-1)]. The obtained degradation impurity was further assessed with respect to its mutagenic potential using commercial Ames MPF 98/100 microplate format mutagenicity assay kit equipped with Salmonella typhimurium strains TA 98 and TA 100. Both strains were exposed to six concentrations (in a range of 0.16-5.0mg/mL) of DKP in the presence and absence of metabolic activation system. No mutagenic effect was observed confirming that the presence of DKP in IMD final dosage form has no impact on cancer initiation. PMID:24021249

Regulska, Katarzyna; Murias, Marek; Stanisz, Beata; Regulski, Mi?osz

2013-11-18

305

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

PubMed Central

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

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

2012-01-01

306

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

PubMed Central

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

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

2011-01-01

307

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 Central

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 C8, 50 mm × 2.1 mm, 1.7 ?m particle size column with a mobile containing a gradient mixture of solution A (0.10 % v/v o-phosphoric acid in water) and solution B (0.10% v/v o-phosphoric acid in methanol). The flow rate was set at 0.40 mL/min and the run time was 6.0 min. The drug substance was subjected to the stress studies of hydrolysis, oxidation, photolysis, and thermal degradation. Abacavir sulfate was found to degrade significantly under acidic hydrolysis and oxidative stress conditions. The formed degradation products were reported and were well-resolved from Abacavir and its related substances. The mass balance was found to be satisfactory in all of the stress conditions, thus proving the stability-indicating capability of the method. The developed UHPLC method was validated to be in agreement with ICH requirements and found to be rapid, accurate, precise, linear, specific, and suitable for the quantitative determination of related substances and degradants in the bulk drug samples of Abacavir sulfate. PMID:23264939

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

2012-01-01

308

A validated stability-indicating normal phase LC method for clopidogrel bisulfate and its impurities in bulk drug and pharmaceutical dosage form.  

PubMed

A novel stability-indicating normal phase liquid chromatographic (NP-LC) method was developed for the determination of purity of clopidogrel drug substance and drug products in bulk samples and pharmaceutical dosage forms in the presence of its impurities and degradation products. This method is capable of separating all the related substances of clopidogrel along with the chiral impurities. This method can be also be used for the estimation of assay of clopidogrel in drug substance as well as in drug product. The method was developed using Chiralcel OJ-H (250mmx4.6mm, 5microm) column. n-Hexane, ethanol and diethyl amine in 95:5:0.05 (v/v/v) ratio was used as a mobile phase. The eluted compounds were monitored at 240nm. Clopidogrel bisulfate was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. The degradation products were well resolved from main peak and its impurities, proving the stability-indicating power of the method. The developed method was validated as per International Conference on Harmonization (ICH) guidelines with respect to specificity, limit of detection, limit of quantification, precision, linearity, accuracy, robustness and system suitability. PMID:20074888

Durga Rao, Dantu; Kalyanaraman, L; Sait, Shakil S; Venkata Rao, P

2010-05-01

309

Development and validation of a stability-indicating capillary zone electrophoretic method for the assessment of entecavir and its correlation with liquid chromatographic methods.  

PubMed

A stability-indicating capillary zone electrophoresis (CZE) method was validated for the analysis of entecavir in pharmaceutical formulations, using nimesulide as an internal standard. A fused-silica capillary (50 µm i.d.; effective length, 40 cm) was used while being maintained at 25°C; the applied voltage was 25 kV. A background electrolyte solution consisted of a 20 mM sodium tetraborate solution at pH 10. Injections were performed using a pressure mode at 50 mbar for 5 s, with detection at 216 nm. The specificity and stability-indicating capability were proven through forced degradation studies, evaluating also the in vitro cytotoxicity test of the degraded products. The method was linear over the concentration range of 1-200 µg mL(-1) (r(2) = 0.9999), and was applied for the analysis of entecavir in tablet dosage forms. The results were correlated to those of validated conventional and fast LC methods, showing non-significant differences (p > 0.05). PMID:21415508

Dalmora, Sergio Luiz; Nogueira, Daniele Rubert; D'Avila, Felipe Bianchini; Souto, Ricardo Bizogne; Leal, Diogo Paim

2011-01-01

310

Improved efficiency and stability of secnidazole – An ideal delivery system  

PubMed Central

Secnidazole (?,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 ?g/ml, respectively whereas MIC of the pure secnidazole drug against the same bacteria were found to be 4.3 and 6.07 ?g/ml, respectively.

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

2014-01-01

311

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

PubMed

Secnidazole (?,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 ?g/ml, respectively whereas MIC of the pure secnidazole drug against the same bacteria were found to be 4.3 and 6.07 ?g/ml, respectively. PMID:25561882

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

2015-01-01

312

ESI-MSn and LC-ESI-MS studies to characterize forced degradation products of bosentan and a validated stability-indicating LC-UV method.  

PubMed

The present study reports the characterization of forced degradation products of bosentan and a validated stability-indicating HPLC method for the stability testing of bosentan tablets. The forced degradation was carried out under the conditions of hydrolysis, oxidation, dry heat and photolysis. The drug was found unstable in acid, alkali and oxidative media whereas stable to the hydrolysis in water, to dry heat and to photolysis. In total, six degradation products were formed in all conditions which were resolved in a single run on a C-18 column with gradient elution using ammonium acetate buffer (pH 4.5, 5.0mM), methanol and acetonitrile. Structures of all the degradation products were characterized through +ESI-MS(n) and LC-ESI-MS spectral data of bosentan as well as LC-ESI-MS spectral data of the products. The products II-VI were characterized as 6-amino-[2,2']bipyrimidinyl-4,5-diol, 6-amino-5-(2-methoxyphenoxy)-[2,2']-bipyrimidinyl-4-ol, 2-[6-amino-5-(2-methoxyphenoxy)-[2,2']-bipyrimidinyl-4-yloxy]-ethanol, 4-tert-butyl-N-[6-(1-methoxyethoxy)-5-(2-methoxyphenoxy)-[2,2']-bipyrimidinyl-4-yl]-benzenesulfonamide and 4-tert-butyl-N-[6-hydroxy-5-(2-methoxyphenoxy)-[2,2']bipyrimidinyl-4-yl]-benzenesulfonamide, respectively. The peak of the product I was found to be due to two secondary degradation products which co-eluted and were characterized as ?-hydroxyethyl p-tert-butylphenylsulfonate (Ia) and 2-[2-(2-hydroxyethoxy)-phenoxy]-ethanol (Ib). These products were formed due to hydrolysis of sulfonamide and alkylaryl ether and the diaryl ether linkages as well as dehydration of the primary alcohol group. The most probable degradation mechanisms were proposed. The HPLC method was found to be stability-indicating, linear (2-100 ?g ml(-1)), accurate, precise, sensitive, specific, rugged and robust for quantitation of the drug. The method was applied to the stability testing of the commercially available bosentan tablets successfully. PMID:22999302

Bansal, Gulshan; Singh, Ranjit; Saini, Balraj; Bansal, Yogita

2013-01-01

313

Support vector regression and artificial neural network models for stability indicating analysis of mebeverine hydrochloride and sulpiride mixtures in pharmaceutical preparation: A comparative study  

NASA Astrophysics Data System (ADS)

A comparison between support vector regression (SVR) and Artificial Neural Networks (ANNs) multivariate regression methods is established showing the underlying algorithm for each and making a comparison between them to indicate the inherent advantages and limitations. In this paper we compare SVR to ANN with and without variable selection procedure (genetic algorithm (GA)). To project the comparison in a sensible way, the methods are used for the stability indicating quantitative analysis of mixtures of mebeverine hydrochloride and sulpiride in binary mixtures as a case study in presence of their reported impurities and degradation products (summing up to 6 components) in raw materials and pharmaceutical dosage form via handling the UV spectral data. For proper analysis, a 6 factor 5 level experimental design was established resulting in a training set of 25 mixtures containing different ratios of the interfering species. An independent test set consisting of 5 mixtures was used to validate the prediction ability of the suggested models. The proposed methods (linear SVR (without GA) and linear GA-ANN) were successfully applied to the analysis of pharmaceutical tablets containing mebeverine hydrochloride and sulpiride mixtures. The results manifest the problem of nonlinearity and how models like the SVR and ANN can handle it. The methods indicate the ability of the mentioned multivariate calibration models to deconvolute the highly overlapped UV spectra of the 6 components' mixtures, yet using cheap and easy to handle instruments like the UV spectrophotometer.

Naguib, Ibrahim A.; Darwish, Hany W.

2012-02-01

314

Support vector regression and artificial neural network models for stability indicating analysis of mebeverine hydrochloride and sulpiride mixtures in pharmaceutical preparation: a comparative study.  

PubMed

A comparison between support vector regression (SVR) and Artificial Neural Networks (ANNs) multivariate regression methods is established showing the underlying algorithm for each and making a comparison between them to indicate the inherent advantages and limitations. In this paper we compare SVR to ANN with and without variable selection procedure (genetic algorithm (GA)). To project the comparison in a sensible way, the methods are used for the stability indicating quantitative analysis of mixtures of mebeverine hydrochloride and sulpiride in binary mixtures as a case study in presence of their reported impurities and degradation products (summing up to 6 components) in raw materials and pharmaceutical dosage form via handling the UV spectral data. For proper analysis, a 6 factor 5 level experimental design was established resulting in a training set of 25 mixtures containing different ratios of the interfering species. An independent test set consisting of 5 mixtures was used to validate the prediction ability of the suggested models. The proposed methods (linear SVR (without GA) and linear GA-ANN) were successfully applied to the analysis of pharmaceutical tablets containing mebeverine hydrochloride and sulpiride mixtures. The results manifest the problem of nonlinearity and how models like the SVR and ANN can handle it. The methods indicate the ability of the mentioned multivariate calibration models to deconvolute the highly overlapped UV spectra of the 6 components' mixtures, yet using cheap and easy to handle instruments like the UV spectrophotometer. PMID:22137012

Naguib, Ibrahim A; Darwish, Hany W

2012-02-01

315

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

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

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

2013-01-01

316

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

PubMed

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

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

2013-03-01

317

Development and validation of an HPLC stability-indicating method for identification and assay of elemental iron(II) in pharmaceutical drug products using reversed-phase HPLC.  

PubMed

Ferrous sulfate tablets are a supplementary iron source for people who suffer from iron deficiency anemia. A simple, fast, and QC-friendly HPLC method was developed and validated to determine elemental iron in ferrous sulfate drug products. A TSK-GEL Super octadecylsilyl column (50 x 4.6 mm id, 2 microm particle size) with a mobile phase consisting of 0.06 M methanesulfonic acid in water-acetonitrile (40 + 60, v/v) and UV detection at 282 nm were used for this method. Separation of the elemental iron peak from the matrix was achieved within 5 min. This method was successfully validated according to International Conference on Harmonization guidelines, and shown to be stability-indicating for the shelf-life samples of ferrous sulfate tablets, as well as selective for the analyte of interest. PMID:21919357

Dias, Neil C; Rustum, Abu M

2011-01-01

318

Stability-indicating RP-LC method for determination of azilsartan medoxomil and chlorthalidone in pharmaceutical dosage forms: application to degradation kinetics.  

PubMed

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 ?m) 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 ?g mL(-1) for AZL and CLT, respectively (r (2)?=?0.9999). LODs for AZL and CLT were 0.90 and 0.32 ?g mL(-1), whereas LOQs were 2.72 and 0.98 ?g 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

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

2014-10-01

319

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

PubMed

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

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

2014-09-15

320

Development and validation of a stability-indicating high performance liquid chromatographic (HPLC) method for the determination of related substances of micafungin sodium in drug substances.  

PubMed

An isocratic, sensitive and stability-indicating high performance liquid chromatographic (HPLC) method for separation and determination of the related substances of micafungin sodium was developed. The chromatographic separation was achieved on Agilent Zorbax SB-C18 column (250 × 4.6 mm, 5 ?m). Forced degradation study con?rmed that the newly developed method was speci?c and selective to the degradation products. The performance of the method was validated according to the present ICH guidelines for speci?city, linearity, accuracy, precision and robustness. Regression analysis showed correlation coefficient value greater than 0.999 for micafungin sodium and its six impurities. Limit of detection of impurities was in the range of 0.006%-0.013% indicating the high sensitivity of the newly developed method. Accuracy of the method was established based on the recovery obtained between 98.2% and 102.0% for all impurities. RSD obtained for the repeatability and intermediate precision experiments, was less than 1.0%. The method was successfully applied to quantify related substances of micafungin sodium in bulk drugs. PMID:24284389

Zhu, Shengsheng; Meng, Xiang; Su, Xin; Luo, Yongwei; Sun, Zuyue

2013-01-01

321

A rapid stability-indicating, fused-core HPLC method for simultaneous determination of ?-artemether and lumefantrine in anti-malarial fixed dose combination products  

PubMed Central

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 ?-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 ?-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. ?-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 ?l injection volume. Quantification was performed at 210 nm and 335 nm for ?-artemether and for lumefantrine, respectively. In-silico toxicological evaluation of the related impurities was made using Derek Nexus v2.0®. Results Both ?-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 ?-artemether and 99.7 % (± 0.6%) for lumefantrine. All identified ?-artemether-related impurities were predicted in Derek Nexus v2.0® to have toxicity risks similar to ?-artemether active pharmaceutical ingredient (API) itself. Conclusions A rapid, robust, precise and accurate stability-indicating, quantitative fused-core isocratic HPLC method was developed for simultaneous assay of ?-artemether and lumefantrine. This method can be applied in the routine regulatory quality control of FDC products. The in-silico toxicological investigation using Derek Nexus® indicated that the overall toxicity risk for ?-artemether-related impurities is comparable to that of ?-artemether API. PMID:23631682

2013-01-01

322

Validated stability indicating liquid chromatographic determination of ebastine in pharmaceuticals after pre column derivatization: Application to tablets and content uniformity testing  

PubMed Central

An accurate, simple, sensitive and selective reversed phase liquid chromatographic method has been developed for the determination of ebastine in its pharmaceutical preparations. The proposed method depends on the complexation ability of the studied drug with Zn2+ ions. Reversed phase chromatography was conducted using an ODS C18 (150 × 4.6 mm id) stainless steel column at ambient temperature with UV-detection at 260 nm. A mobile phase containing 0.025%w/v Zn2+ in a mixture of (acetonitril/methanol; 1/4) and Britton Robinson buffer (65:35, v/v) adjusted to pH 4.2, has been used for the determination of ebastine at a flow rate of 1 ml/min. The calibration curve was rectilinear over the concentration range of 0.3 - 6.0 ?g/ml with a detection limit (LOD) of 0.13 ?g/ml, and quantification limit (LOQ) of 0.26 ?g/ml. The proposed method was successfully applied for the analysis of ebastine in its dosage forms, the obtained results were favorably compared with those obtained by a comparison method. Furthermore, content uniformity testing of the studied pharmaceutical formulations was also conducted. The composition of the complex as well as its stability constant was also investigated. Moreover, the proposed method was found to be a stability indicating one and was utilized to investigate the kinetics of alkaline and ultraviolet induced degradation of the drug. The first-order rate constant and half life of the degradation products were calculated. PMID:21554731

2011-01-01

323

Coupled solid phase extraction and microparticle-based stability and purity-indicating immunosensor for the determination of recombinant human myelin basic protein in transgenic milk.  

PubMed

An optical immunosensor was developed and validated on the surface of microparticles for the determination of a biopharmaceutical protein. The recombinant human myelin basic protein (rhMBP) was produced in milk of transgenic cows as a His-tagged fusion protein. Previous work indicated exclusive association of rhMBP with milk casein micelles that hindered direct determination of the protein in milk. In this work, a solid phase extraction using a cation exchange matrix was developed in order to liberate rhMBP from casein micelles. A sandwich-type immunoassay was then used for in-process monitoring of the full-length protein in the presence of major milk proteins. The assay was successfully employed for detection of ultra-traces of rhMBP (LOD=6.04 ng mL(-1)?0.3 n mol L(-1)) and for quantitative determination over a wide concentration range (10.00-10,000.00 ng mL(-1)). The assay was able also to detect the rhMBP in the presence of its human counterpart that lacks the His-tag. The high sensitivity along with the ability of the assay to determine the full length protein enabled monitoring of the stability of rhMBP. The testing protocol is particularly useful for intrinsically unstructured proteins that are extremely sensitive to proteolysis and lack a traceable enzymatic activity. This immunosensor provides a specific, ultrasensitive high throughput tool for in-process monitoring in biopharmaceutical industry. PMID:23618134

Al-Ghobashy, Medhat A; Williams, Martin A K; Laible, Götz; Harding, David R K

2013-05-15

324

Study of forced degradation behaviour of florfenicol by LC and LC-MS and development of a validated stability-indicating assay method.  

PubMed

A stability-indicating high performance liquid chromatography (HPLC) method was developed for the analysis of florfenicol in presence of its two available identified degradation products (thiamphenicol and chlorfenicol). The drug was subjected to different International Conference On Harmonisation (ICH) prescribed stress conditions (hydrolysis, oxidation and photolysis). The products formed under different stress conditions were investigated by liquid chromatography (LC) and liquid chromatography-mass spectrometry (LC-MS). The LC method involved a Knauwer Eurospher C18 thermostated column at 25°C; and ammonium acetate buffer 6.49mM (pH adjusted to 4.5)-methanol (70:30 v/v) as mobile phase. The flow rate and detection wavelength were 1ml/min and 225nm respectively. The drug showed instability under acidic, alkaline and photolytic stress conditions mainly in solution state form; however, it remains stable in solid state form and under oxidative stress conditions. The developed method was validated for linearity, precision, accuracy and specificity. The degradation products were characterized by LC-MS. Through the mass/ionization (m/z) values and fragmentation patterns, two principal degradation products listed in bibliography have been shown: the florfenicol amine and thiamphenicol. Based on the results, a more complete degradation pathway of the drug could be proposed. PMID:23177560

Mistiri, F; Louati, K; Grissa, O; Kallel, M; Safta, F

2012-11-01

325

Development and validation of stability-indicating high performance liquid chromatography method to analyze gatifloxacin in bulk drug and pharmaceutical preparations.  

PubMed

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 ?m) 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 ?g.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

Aljuffali, Ibrahim A; Kalam, Mohd Abul; Sultana, Yasmin; Imran, Ahamad; Alshamsan, Aws

2015-01-01

326

A versatile, stability-indicating and high-throughput ultra-fast liquid chromatography method for the determination of isoflavone aglycones in soybeans, topical formulations, and permeation assays.  

PubMed

There is a growing interest in the pharmaceutical field concerning isoflavones topical delivery systems, especially with regard to their skin care properties and antiherpetic activity. In this context, the present work describes an ultra-fast liquid chromatography method (UFLC) for determining daidzein, glycitein, and genistein in different matrices during the development of topical systems containing isoflavone aglycones (IA) obtained from soybeans. The method showed to be specific, precise, accurate, and linear (0.1 to 5µgmL(-1)) for IA determination in soybean acid extract, IA-rich fraction obtained after the purification process, IA loaded-nanoemulsions, and topical hydrogel, as well as for permeation/retention assays in porcine skin and porcine esophageal mucosa. The matrix effect was determined for all complex matrices, demonstrating low effect during the analysis. The stability indicating UFLC method was verified by submitting IA to acidic, alkaline, oxidative, and thermal stress conditions, and no interference of degradation products was detected during analysis. Mass spectrometry was performed to show the main compounds produced after acid hydrolysis of soybeans, as well as suggest the main degradation products formed after stress conditions. Besides the IA, hydroxymethylfurfural and ethoxymethylfurfural were produced and identified after acid hydrolysis of the soybean extract and well separated by the UFLC method. The method's robustness was confirmed using the Plackett-Burman experimental design. Therefore, the new method affords fast IA analysis during routine processes, extract purification, products development, and bioanalytical assays. PMID:25618656

Nemitz, Marina C; Yatsu, Francini K J; Bidone, Juliana; Koester, Letícia S; Bassani, Valquiria L; Garcia, Cássia V; Mendez, Andreas S L; von Poser, Gilsane L; Teixeira, Helder F

2015-03-01

327

Development and validation of a stability-indicating LC method for the determination of venlafaxine in extended-release capsules and dissolution kinetic studies.  

PubMed

A stability-indicating reversed-phase high-performance liquid chromatography method is developed and validated for the determination of venlafaxine hydrochloride (VEN) in extended-release capsules containing spherical beads and for dissolution studies. The method is carried out on a Luna C(18) column (250 mm x 4.6 mm) maintained at 35 degrees C. The mobile phase is composed of ammonium-acetate buffer 32 mM, adjusted to pH 6.8 with phosphoric acid-acetonitrile-methanol (62:30:8, v/v/v), run at a flow rate of 1.0 mL/min, and detection at 226 nm. Validation parameters such as the specificity, linearity, precision, accuracy, and robustness are evaluated, giving results within the acceptable range. In order to evaluate the best dissolution condition, the dissolution profiles are performed under different conditions, such as media (HCl, water, phosphate buffer), apparatus (I and II), and dissolution rates (50, 75, and 100 rpm). The kinetics release mechanism is evaluated by fitting different models, such as the zero order rate, first order, and Higuchi. Moreover, the proposed method is successfully applied for the assay of VEN in extended-release capsules. PMID:19835686

Bernardi, Larissa S; Oliveira, Paulo R; Murakami, Fábio S; Borgmann, Silvia H M; Arend, Marcela Z; Cardoso, Simone G

2009-10-01

328

Development and validation of stability-indicating high performance liquid chromatography method to analyze gatifloxacin in bulk drug and pharmaceutical preparations  

PubMed Central

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 ?m) 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 ?g.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.

Aljuffali, Ibrahim A.; Kalam, Mohd. Abul; Sultana, Yasmin; Imran, Ahamad; Alshamsan, Aws

2014-01-01

329

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

PubMed

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

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

2006-05-01

330

Improved partial least squares models for stability-indicating analysis of mebeverine and sulpiride mixtures in pharmaceutical preparation: a comparative study.  

PubMed

Performance of partial least squares regression (PLSR) is enhanced in the presented work by three multivariate models, including weighted regression PLSR (Weighted-PLSR), genetic algorithm PLSR (GA-PLSR), and wavelet transform PLSR (WT-PLSR). The proposed models were applied for the stability-indicating analysis of mixtures of mebeverine hydrochloride (meb) and sulpiride (sul) in the presence of their reported impurities and degradation products. The work introduced in this paper aims to compare these different chemometric methods, showing the underlying algorithm for each and making a comparison of analysis results. For proper analysis, a 6-factor, 5-level experimental design was established resulting in a training set of 25 mixtures containing different ratios of the interfering species. A test set consisting of 5 mixtures was used to validate the prediction ability of the suggested models. Leave one out (LOO) and bootstrap were applied to predict number of PLS components. The GA-PLSR proposed method was successfully applied for the analysis of raw material (test set 101.03% ± 1.068, 101.47% ± 2.721 for meb and sul, respectively) and pharmaceutical tablets containing meb and sul mixtures (10.10% ± 0.566, 98.16% ± 1.081 for meb and sul). PMID:21898859

Darwish, Hany W; Naguib, Ibrahim A

2013-05-01

331

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

PubMed Central

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

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

2012-01-01

332

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

PubMed Central

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

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

2013-01-01

333

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

PubMed

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

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

2013-01-01

334

Validated Stability-Indicating HPLC-DAD Method for the Simultaneous Determination of Diclofenac Sodium and Diflunisal in Their Combined Dosage Form  

PubMed Central

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 ?m 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 ?g/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

Shaalan, Rasha A.; Belal, Tarek S.

2013-01-01

335

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

PubMed Central

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

2011-01-01

336

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

PubMed Central

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

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

2013-01-01

337

The Development and Validation of a Stability-Indicating UHPLC-DAD Method for Determination of Perindopril l-Arginine in Bulk Substance and Pharmaceutical Dosage Form.  

PubMed

A stability-indicating ultra-high-performance liquid chromatography (UHPLC) method with a diode array detector was developed and validated for the determination of cis/trans isomers of perindopril l-arginine in bulk substance and pharmaceutical dosage form. The separation was achieved on a Poroshell 120 Hilic (4.6 × 150 mm, 2.7 µm) column using a mobile phase composed of acetonitrile-0.1 % formic acid (20:80 v/v) at a flow rate of 1 mL min(-1). The injection volume was 5.0 µL and the wavelength of detection was controlled at 230 nm. The selectivity of the UHPLC-DAD method was confirmed by determining perindopril l-arginine in the presence of degradation products formed during acid-base hydrolysis and oxidation as well as degradation in the solid state, at an increased relative air humidity and in dry air. The method's linearity was investigated in the ranges 0.40-1.40 µg mL(-1) for isomer I and 0.40-2.40 µg mL(-1) for isomer II of perindopril l-arginine. The UHPLC-DAD method met the precision and accuracy criteria for the determination of the isomers of perindopril l-arginine. The limits of detection and quantitation were 0.1503 and 0.4555 µg mL(-1) for isomer I and 0.0356 and 0.1078 µg mL(-1) for isomer II, respectively. PMID:25400289

Paczkowska, Magdalena; Zalewski, Przemys?aw; Garbacki, Piotr; Talaczy?ska, Alicja; Krause, Anna; Cielecka-Piontek, Judyta

2014-01-01

338

Development and Validation of a Stability-Indicating RP-UPLC Method for Determination of Cloxacillin Sodium in Its Bulk Form and Formulation.  

PubMed

A simple, linear gradient, rapid, precise and stability-indicating RP-UPLC method was developed for the determination of Cloxacillin Sodium in its bulk form and formulation. Ultra performance liquid chromatography, a most promising advancement in a world of chromatography, reduces analysis time, increases reliability through higher resolution, sensitivity and selectivity as well as used as an economic method due to reducing solvent consumption. A chromatographic separation of a drug as well as its degradants was achieved using Waters acquity BEH, 2.1 × 100 mm, 1.7 ?m C18 column with gradient of mobile phase A: phosphate buffer, pH 6.8 and mobile phase B: methanol:acetonitrile (75:25). The drug and degradants were monitored at a detection wavelength of 225 nm with a flow rate of 0.35 mL/min and an injection volume of 10 µL. The temperature of the column and auto sampler compartments was at 30°C and 25°C ± 1°C, respectively. The retention time of the drug was ?6.9 min. The resolution of the drug and degradant peak was >1.5 in all cases. Force degradation of CLOX SOD was carried under alkaline, acidic, oxidative, thermal, photo degradation conditions and it was analyzed by the proposed method. The drug degrades under alkaline, acidic and oxidative conditions but was stable in temperature and light. A developed method was validated as per ICH guidelines using validation parameters such as precision, linearity and range, limit of quantification, specificity, assay and robustness. PMID:25368408

Patel, Nikita; Contractor, Pooja; Keshrala, Rajesh; Patel, Parag R; Shridhar, Bhimagoni

2014-11-01

339

Determination of itopride hydrochloride in human plasma by RP-HPLC with fluorescence detection and its use in bioequivalence study.  

PubMed

A sensitive, selective and simple method using a precipitation of protein with 10% perchloric acid, followed by high-performance liquid chromatography (HPLC) with fluorescence detection was developed for the determination of itopride hydrochloride in human plasma, using levofloxacin as the internal standard (IS). Chromatographic separation was obtained within 7.0 min using a reverse phase Hypersil BDS C(18) (250 mm x 4.6 mm, 5 microm) column and an isocratic mobile phase, constituting of a mixture of 0.1 mol/l ammonium acetate-methanol (30:70, v/v) flowing at 1.1 ml/min. The excitation and emission wavelengths were set at 304 and 344 nm, respectively. The method was validated over the concentration range of 5 ng/ml to 1000.0 ng/ml. The lower limit of quantitation (LLOQ) was 5 ng/ml. The extractive recovery of itopride hydrochloride from the biological matrix was more than 80.77%. The intra-day accuracy of the drug containing serum samples was more than 82.94% with a precision of 2.81-4.37%. The inter-day accuracy was 82.91% or more, with a precision of 6.89-9.54%. The limit we have used (70-143%) is based on the local regulatory authority (SFDA). The developed method was validated and successfully applied to bioequivalence studies of itopride hydrochloride in healthy male volunteers. PMID:19101632

Ma, Jing; Yuan, Li-Hua; Ding, Mei-Juan; Zhang, Jun; Zhang, Qing; Xu, Qun-Wei; Zhou, Xue-Min

2009-03-01

340

Development and Validation of RP-HPLC Method for the Determination of Methamphetamine and Propranolol in Tablet Dosage Form.  

PubMed

A new isocratic reversed-phase HPLC method with diode-array UV detection was developed and validated for the determination of methamphetamine and propranolol in tablet dosage forms. Chromatography was carried out on an XTerra RP18 (150×4.6 mm, 5 ?m) column using 50 mM pyrrolidine (pH 11.5) - acetonitrile (50:50, v/v) as mobile phase at a flow rate of 1 ml/min. Spectrophotometric detection was performed at a wavelength of 214 nm. The linearity was established over the concentration range of 0.075-0.60 mg/ml for both drugs. The correlation coefficients (r(2)) were ?0.9998 in each case. The relative standard deviation values for intermediate precision studies were <1%. Statistical analysis of the data showed that the method was precise, accurate, reproducible and selective for the analysis of methamphetamine and propranolol drugs. The method was successfully employed for the determination of propranolol and methamphetamine in commercially available tablet dosage form. PMID:22707828

Shabir, G A

2011-07-01

341

Effect of chemically bonded stationary phases and mobile phase composition on beta-blockers retention in RP-HPLC.  

PubMed

The effects of stationary and mobile phase on retention of 18 beta-adrenolytic drugs (beta-blockers) have been studied. Four 'deactivated surface' stationary phases (polar-embedded or end-capped) were examined. Special attention was drawn to the cholesterolic (SG-CHOL) and alkylamide (SG-AP) stationary phases, and their application for analysis of the compounds. The retention of analyzed substances was also examined in terms of mobile phase composition. Sixteen different configurations of mobile phases were prepared, all based on methanol and acetonitrile with ammonium acetate and ammonium formate. The difference in retention between ammonium formate and acetate water solutions, and peak shape changes related to the addition of triethylamine (TEA), were investigated. Principal component analysis was used to find the similarities between stationary phases. Polar-embedded phases synthesized on the same sorbent possess very similar properties. All phases based on silica gel compared with the monolithic column also showed similarities in retention of beta-blockers. The addition of TEA to the mobile phase did not influence strongly the retention, and analysis of asymmetry factors showed only a little peak broadening for a few compounds on the monolithic column. PMID:18800332

Buszewski, Boguslaw; Welerowicz, Tomasz; Kowalkowski, Tomasz

2009-03-01

342

Development and Validation of RP-HPLC Method for Simultaneous Estimation of Cefpodoxime Proxetil and Dicloxacillin Sodium in Tablets  

PubMed Central

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 ?m) 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 ?g/ml for cefpodoxime proxetil (r2=0.9996) and 5-50 ?g/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 ?g/ml and limit of quantification 0.220, 1.116 ?g/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

Acharya, D. R.; Patel, Dipti B.

2013-01-01

343

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

Microsoft Academic Search

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

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

2012-01-01

344

Validated RP-HPLC and HPTLC methods for determination of anti-inflammatory bis-indole alkaloid in Desmodium gangeticum.  

PubMed

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

Yadav, Akhilesh K; Gupta, Madan M

2014-01-01

345

Separation and Measurement of Plant Alkaloid Enantiomers by RP-HPLC Analysis of their Fmoc-Alanine Analogs  

Technology Transfer Automated Retrieval System (TEKTRAN)

Plants often synthesize secondary metabolites that are enantiomers. Enantiomers can cause very different physiological responses. Ammodendrine (1) and anabasine (2) are teratogens that can cause congenital malformations in livestock and enantiomeric forms of each have been found in Lupinus spp. an...

346

Simplified RP-HPLC method for multi-residue analysis of abamectin, emamectin benzoate and ivermectin in rice.  

PubMed

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

Xie, Xianchuan; Gong, Shu; Wang, Xiaorong; Wu, Yinxing; Zhao, Li

2011-01-01

347

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

PubMed Central

An HPLC method with ultraviolet-visible spectrophotometry detection has been optimized and validated for the simultaneous determination of phenolic compounds, such as butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) as antioxidants, and octyl methyl cinnamate (OMC) as UVB-filter in several personal care products. The dynamic range was between 1 to 250?mg/L with relative standard deviation less than 0.25% (n = 4). Limits of detection for BHA, BHT, and OMC were 0.196, 0.170, and 0.478?mg/L, respectively. While limits of quantification for BHA, BHT, and OMC were 0.593, 0.515, and 1.448?mg/L, respectively. The recovery for BHA, BHT, and OMC was ranged from 92.1–105.9%, 83.2–108.9%, and 87.3–103.7%, respectively. The concentration ranges of BHA, BHT, and OMC in 12 commercial personal care samples were 0.13–4.85, 0.16–2.30, and 0.12–65.5?mg/g, respectively. The concentrations of phenolic compounds in these personal care samples were below than maximum allowable concentration in personal care formulation, that is, 0.0004–10?mg/g, 0.002–5?mg/g, and up to 100?mg/g for BHA, BHT, and OMC, respectively. PMID:21760792

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

2011-01-01

348

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...

349

Development and Validation of RP-HPLC Method for Simultaneous Estimation of Atorvastatin Calcium and Fenofibrate in Tablet Dosage Forms  

PubMed Central

A reverse phase high performance liquid chromatographic method was developed for the simultaneous estimation of atorvastatin calcium and fenofibrate in tablet formulation. The separation was achieved by Luna C18 column and methanol:acetate buffer pH 3.7 (82:18 v/v) as mobile phase, at a flow rate of 1.5 ml/min. Detection was carried out at 248 nm. Retention time of atorvastatin calcium and fenofibrate was found to be 3.02+0.1 and 9.05+0.2 min, respectively. The method has been validated for linearity, accuracy and precision. Linearity for atorvastatin calcium and Fenofibrate were in the range of 1-5 ?g/ml and 16-80 ?g/ml, respectively. The mean recoveries obtained for Atorvastatin calcium and fenofibrate were 101.76% and 100.06%, respectively. Developed method was found to be accurate, precise, selective and rapid for simultaneous estimation of atorvastatin calcium and fenofibrate in tablets. PMID:20046730

Jain, N.; Raghuwanshi, R.; Jain, Deeti

2008-01-01

350

Analytical method development and validation of prasugrel in bulk and its pharmaceutical formulation using the RP-HPLC method  

PubMed Central

Purpose: This study was designed to develop and validate a simple, sensitive, precise, and specific reverse phase high-performance liquid chromatographic (HPLC) method for the determination of prasugrel in bulk and its tablet dosage forms. Materials and Methods: The HPLC separation was carried out by reverse phase chromatography on an inertsil ODS-3V column (5 ?m; 250 × 4.6mm2) with a mobile phase composed of 0.02 M potassium dihydrogen orthophosphate, 0.02 M dipotassium hydrogen orthophosphate in water:acetonitrile (30:70 v/v) in isocratic mode at a flow rate of 1 ml/min. The detection was monitored at 210 nm. Results: The calibration curve for prasugrel was linear from 100 to 600 ?g/ml. The inter-day and intra-day precision was found to be within limits. The proposed method has adequate sensitivity, reproducibility, and specificity for the determination of prasugrel in bulk and its tablet dosage forms. The limit of detection and limit of quantification for prasugrel were found to be 0.25 ?g/ml and 0.75 ?g /ml, respectively. Accuracy (recoveries: 99.8–101.2%) and reproducibility were found to be satisfactory. Conclusion: The proposed method is simple, fast, accurate, and precise for the simultaneous quantification of prasugrel in the dosage form, bulk drugs as well as for routine analysis in quality control. PMID:23781451

Ishaq, B. Mohammed; Prakash, K. Vanitha; Mohan, G. Krishna

2011-01-01

351

Development and Validation of RP-HPLC Method for the Determination of Methamphetamine and Propranolol in Tablet Dosage Form  

PubMed Central

A new isocratic reversed-phase HPLC method with diode-array UV detection was developed and validated for the determination of methamphetamine and propranolol in tablet dosage forms. Chromatography was carried out on an XTerra RP18 (150×4.6 mm, 5 ?m) column using 50 mM pyrrolidine (pH 11.5) – acetonitrile (50:50, v/v) as mobile phase at a flow rate of 1 ml/min. Spectrophotometric detection was performed at a wavelength of 214 nm. The linearity was established over the concentration range of 0.075-0.60 mg/ml for both drugs. The correlation coefficients (r2) were ?0.9998 in each case. The relative standard deviation values for intermediate precision studies were <1%. Statistical analysis of the data showed that the method was precise, accurate, reproducible and selective for the analysis of methamphetamine and propranolol drugs. The method was successfully employed for the determination of propranolol and methamphetamine in commercially available tablet dosage form. PMID:22707828

Shabir, G. A.

2011-01-01

352

Development and Validation of a RP-HPLC Method for Estimation of Prulifloxacin in Tablet Dosage Form  

PubMed Central

A simple, precise, rapid, accurate and economic reverse phase high performance liquid chromatographic method has been developed for the estimation of prulifloxacin in tablet dosage form. The separation was achieved by using octadecylsilane column (C18) and KH2PO4 buffer: acetonitrile adjusted to pH 7.3 with triethyl amine in proportion of 10:90 v/v as mobile phase, at a flow rate of 1.0 ml/min. The detection was carried out at 278 nm. The retention time of prulifloxacin was found to be 2.4 min. The limit of detection and limit of quantitation were found to be 0.14 ?g/ml and 0.42 ?g/ml respectively. The accuracy and reliability of the proposed method was ascertained by evaluating various validation parameters like linearity, precision, accuracy and specificity according to ICH guidelines. The proposed method provides an accurate and precise quality control tool for routine analysis of prulifloxacin in tablet dosage form. PMID:22923873

Singh, S.; Singh, U. K.; Singh, R. M.; Singh, G. N.; Mathur, S. C.; Saini, P. K.; Yadav, A.; Gupta, V.; Duggal, D.

2011-01-01

353

Development and validation of RP-HPLC method for the quantitative estimation of ?s1-genetic variants in goat milk.  

PubMed

A high-performance liquid chromatographic (HPLC) method was developed and validated for separation and quantification of the most common genetic variants of ?s1-casein in goat's milk, to evaluate the effect of ?s1-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 ?s1-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 ?s1-casein in milk. PMID:24629953

Montalbano, Maria; Tortorici, Lina; Mastrangelo, Salvatore; Sardina, Maria Teresa; Portolano, Baldassare

2014-08-01

354

Development and validation of RP-HPLC method: scope of application in the determination of oil solubility of paclitaxel.  

PubMed

A simple, reproducible, feasible and innovative reversed-phase high-performance liquid chromatographic method was developed and validated for the quantitative determination of paclitaxel dissolved in various oils. The method was validated after extraction of the analyte from capryol 90, triacetin and olive oil. The method was conducted on a Hypersil BDS C18 column, 250 × 4.6 mm, 5 µm particle size, with a mobile phase composed of acetonitrile: 10 mM KH2PO4 buffer (pH 3.5) (55:45, v/v) and detection at 227 nm. The linearity, in the range of 5 to 50 µg/mL, presented determination coefficients of 0.9983, 0.9997 and 0.9990 in capryol 90, triacetin and olive oil, respectively, calculated by the least-squares regression method. Intra-day precision values for percentages recovered were 0.68 to 0.80, 0.83 to 1.13 and 0.97 to 1.88, and inter day precision values were 1.52 to 1.92, 1.43 to 1.83 and 1.26 to 2.06 for capryol 90, triacetin and olive oil, respectively. The recovery of paclitaxel from the capryol 90, triacetin and olive oil ranged from 97.94 to 103.55, 96.85 to 103.27 and 97.14 to 103.64%, respectively. This developed and validated method was successfully applied to quantitatively assess paclitaxel dissolved in various oils. The solubility of paclitaxel was found to be higher in triacetin than in other tested oils. PMID:23293041

Choudhury, Hira; Gorain, Bapi; Karmakar, Sanmoy; Pal, Tapan Kumar

2014-01-01

355

RP-HPLC analytical method development and optimization for quantification of donepezil hydrochloride in orally disintegrating tablet.  

PubMed

An easy, fast and validated RV-HPLC method was invented to quantify donepezil hydrochloride in drug solution and orally disintegrating tablet. The separation was carried out using reversed phase C-18 column (Agilent Eclipse Plus C-18) with UV detection at 268 nm. Method optimization was tested using various composition of organic solvent. The mobile phase comprised of phosphate buffer (0.01M), methanol and acetonitrile (50:30:20, v/v) adjusted to pH 2.7 with phosphoric acid (80%) was found as the optimum mobile phase. The method showed intraday precision and accuracy in the range of 0.24% to -1.83% and -1.83% to 1.99% respectively, while interday precision and accuracy ranged between 1.41% to 1.81% and 0.11% to 1.90% respectively. The standard calibration curve was linear from 0.125 ?g/mL to 16 ?g/mL, with correlation coefficient of 0.9997±0.00016. The drug solution was stable under room temperature at least for 6 hours. System suitability studies were done. The average plate count was > 2000, tailing factor <1, and capacity factor of 3.30. The retention time was 5.6 min. The HPLC method was used to assay donepezil hydrochloride in tablet and dissolution study of in-house manufactured donepezil orally disintegrating tablet and original Aricept. PMID:24035953

Liew, Kai Bin; Peh, Kok Khiang; Fung Tan, Yvonne Tze

2013-09-01

356

RP?HPLC Assay of Rofecoxib from Pharmaceutical Dosage Forms and Human Plasma and Its Drug Dissolution Studies  

Microsoft Academic Search

A high performance liquid chromatographic (HPLC) method is described for the determination of rofecoxib (RFC) in bulk drug, tablets, and human plasma samples. The methods are linear over the concentration ranges 0.005–30.0 and 0.010–10 µg mL in mobile phase and human plasma, respectively. Chromatography was carried out on a reversed phase Spherisorb ODSI column using a mixture of acetonitrile:methanol: 0.067

Ayhan Sava?er; Yalçin Özkan; Cansel K. Özkan; Çetin Ta?; Sibel A. Özkan

2004-01-01

357

Development and Validation of RP-HPLC Method for Simultaneous Estimation of Cefpodoxime Proxetil and Dicloxacillin Sodium in Tablets.  

PubMed

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 ?m) 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 ?g/ml for cefpodoxime proxetil (r(2)=0.9996) and 5-50 ?g/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 ?g/ml and limit of quantification 0.220, 1.116 ?g/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

Acharya, D R; Patel, Dipti B

2013-01-01

358

Internet Addiction: Stability and Change  

ERIC Educational Resources Information Center

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

Huang, Chiungjung

2010-01-01

359

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

PubMed Central

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

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

2013-01-01

360

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

PubMed

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

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

2009-11-01

361

Development and validation of stability indicating method for determination of sertraline following ICH guidlines and its determination in pharmaceuticals and biological fluids  

PubMed Central

Background Sertraline is a well known antidepressant drug which belongs to a class called selective serotonin reuptake inhibitor. Most published methods do not enable studying the stability of this drug in different stress conditions. Results Two new methods were developed for the determination of sertraline (SER). Both methods are based on coupling with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) in borate buffer of pH 7.8 and measuring the reaction product spectrophotometrically at 395 nm (Method I) or spectrofluorimetrically at 530 nm upon excitation at 480 nm (Method II). The response-concentration plots were rectilinear over the range 2-24 ?g/mL and 0.25-5 ?g/mL for methods I and II respectively with LOD of 0.18 ?g/mL and 0.07 ?g/mL, and LOQ of 0.56 ?g/mL and 0.21 ?g/mL for methods I and II, respectively. Conclusion Both methods were applied to the analysis of commercial tablets and the results were in good agreement with those obtained using a reference method. The fluorimetric method was further applied to the in vivo determination of SER in human plasma. A proposal of the reaction pathway was presented. The spectrophotometric method was extended to stability study of SER. The drug was exposed to alkaline, acidic, oxidative and photolytic degradation according to ICH guidelines. Moreover, the method was utilized to investigate the kinetics of oxidative degradation of the drug. The apparent first order rate constant and t1/2 of the degradation reaction were determined. PMID:21996025

2011-01-01

362

ESI-MS/MS stability-indicating bioanalytical method development and validation for simultaneous estimation of donepezil, 5-desmethyl donepezil and 6-desmethyl donepezil in human plasma.  

PubMed

A bioanalytical method was developed and validated to estimate donepezil, 6-desmethyl donepezil and 5-desmethyl donepezil simultaneously in human plasma using galantamine as an internal standard (IS). The chromatographic separation was achieved on a reverse-phase XTerra RP (150?×?4.6?mm, 5?µm) column without affecting recovery (mean recovery?>?60% with CV?stability was successfully achieved for 211?days at -15?°C storage temperature. The method was successfully applied to a clinical study after administration of 10?mg donepezil tablets to healthy male Indian volunteers. PMID:22120680

Khuroo, Arshad H; Gurule, Sanjay J; Monif, Tausif; Goswami, Dipanjan; Saha, Arabinda; Singh, Santosh K

2012-05-01

363

Stability-indicating methods for the determination of mosapride citrate in the presence of its degradation products according to ICH guidelines.  

PubMed

In the present work, different spectrophotometric methods and one spectrofluorimetric method have been developed and validated for the determination of mosapride citrate in the presence of its acid-induced degradation products. The drug was subjected to stress stability study including acid, alkali, oxidative, photolytic, and thermal stress degradation. The developed spectrophotometric methods included the use of first order derivative ((1)D), derivative of ratio spectra ((1)DD), mean centring of ratio spectra (MC) and H-point standard additions (HPSAM) spectrophotometric methods. For (1)D method, the peaks amplitudes at 282.8 and 319.6 nm were measured, while for (1)DD method those at 308 nm and 323 nm were measured. Mean centring of ratio spectra method used the values at 317 nm for calibration, while for HPSAM the absorbance at 273 and 288.6 nm were used. These methods were successfully applied for determination of mosapride in the concentration range of 5-70 µg.ml(-1). The spectrofluorimetric method was based on measuring the native fluorescence of mosapride in 0.1 M NaOH using ?(excitation) 276 nm and ?(emission) 344 nm and 684 nm with linearity ranges of 50-3000 ng.ml(-1) and 50-9000 ng.ml(-1), respectively. All the developed methods were validated according to the International Conference on Harmonization (ICH) guidelines and were applied for bulk powder and dosage form. The results obtained were statistically compared to each other using one-way ANOVA testing. PMID:21337721

Hegazy, Maha A; Yehia, Ali M; Mostafa, Azza A

2012-02-01

364

Development and validation of a stability-indicating high-performance liquid chromatography method for the simultaneous determination of albuterol, budesonide, and ipratropium bromide in compounded nebulizer solutions.  

PubMed

In recent years, there has been a large increase in the use of pharmaceutical compounding to prepare medications that are not commercially available. The treatment of asthma typically includes the use of albuterol (ALB), ipratropium bromide (IPB), and/or budesonide (BUD) nebulizer solutions. There is currently no commercially available nebulizer solution containing all three of these compounds, and patients must rely on often-unregulated compounding. There is a distinct need for methodologies that can be used to analyze compounded formulations to ensure patient safety. We report an HPLC-UV method to separate and quantitate ALB, IPB, and BUD in nebulizer solutions. The method used a gradient elution to achieve separation via an RP C18 column. The method was validated, showed good selectivity, and was linear over several orders of magnitude. The method was applied to the analysis of nebulizer solutions and determination of their storage stability. Significant ALB-dependent degradation occurred within 5 h in solutions formulated with the free base of ALB, while those containing the sulfate salt of ALB produced no degradation. Alkali solutions can cause base-catalyzed hydrolysis of IPB and degradation of BUD. Compounded formulations containing ALB need to include an acid to control pH and prevent degradation. PMID:21391487

Blewett, Anthony J; Varma, Deepti; Gilles, Tiffany; Butcher, Rashidi; Jacob, Jaini; Amazan, Jean; Jansen, Susan A

2011-01-01

365

Determination of Cefixime by a Validated Stability-Indicating HPLC Method and Identification of its Related Substances by LC-MS/MS Studies  

PubMed Central

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 ?m) 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 ?g 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

Talebpour, Zahra; Pourabdollahi, Hakimeh; Rafati, Hasan; Abdollahpour, Asem; Bashour, Yusef; Aboul-Enein, Hassan Y.

2013-01-01

366

Capability measurement of size-exclusion chromatography with a light-scattering detection method in a stability study of bevacizumab using the process capability indices.  

PubMed

In this study, we investigated if the size-exclusion chromatography coupled with light-scattering and refractive index detection (SEC/LS/RI) method is fitted for its intended purpose and checked if the analytical method is able to provide enough conforming results. For this, the process capability indices Cp, Cpk, and Cpm were computed. The traditional X-chart and moving range (MR) chart were used by the same analyst to monitor the equipment in the laboratory over a 1-year period. For this, a bovine serum albumin (BSA) sample (0.3 mg mL(-1)) with a nominal Mw of 66.4 kDa was analyzed each working day. The results confirmed that the analytical method is in-control and stable. To determine whether the given process meets the present capability requirement and runs under the desired quality conditions, the Pearn and Shu (2003) method based on the lower confidence bound C on Cpm was used. The estimator Cpm was 1.81, and the lower confidence bound C was 1.40. We therefore conclude that the true value of the method capability Cpm is no less than 1.40 with a 95% level of confidence. This result indicates that the method is satisfactory and no stringent precision control is required. The usefulness of this method was applied in the characterization of bevacizumab commercial pharmaceutical preparations stored under different conditions that lead to aggregation. In this case, the computed Cpm index was 0.98 (0.70, 1.26), which indicates that the method does not comply with the specification limits and needs to be revised. The quality improvement effort should: (1) reduce the uncertainty in the absolute Mw determination; (2) either move the process mean closer to the target value or reduce the process variation, i.e. improve the method accuracy (?-T) and precision (?(2)). On this point, the Bayesian posterior distribution of the mean and standard deviation pointed out the need to control the precision but specially accuracy in order to reduce the overall uncertainty of analytical method and thus, the method is capable. PMID:24786652

Oliva, Alexis; Llabrés, Matías; Fariña, José B

2014-08-01

367

Environmental Indicators  

NSDL National Science Digital Library

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

368

Development and validation of a stability-indicating assay method for simultaneous determination of perindopril and indapamide in combined dosage form by reversed-phase high-performance liquid chromatography.  

PubMed

An approach of forced degradation study was successfully applied for the development of a stability-indicating assay method for simultaneous determination of perindopril and indapamide in a formulation in the presence of its degradation products. The method showed adequate separation of perindopril and indapamide from their associated main impurities and degradation products. Separation was achieved on an XTerra RP18, 5 microm, 150 x 4.6 mm id column at 55 degrees C by using the mobile phase NaH2PO4 buffer (pH 2.0; 0.005 M)-acetonitrile (75 + 25, v/v) at a flow rate of 1 mL/min and UV detection at 215 nm. Comprehensive stress testing of perindopril and indapamide was carried out according to the International Conference on Harmonization (ICH) guideline Q1A (R2). The specificity of the method was determined by assessing interference from the placebo and by stress testing of the drug (forced degradation). The drug was subjected to acid hydrolysis, base hydrolysis, oxidation, dry heat, and photolysis to apply stress conditions. There were no other coeluting, interfering peaks from excipients, impurities, or degradation products due to variable stress conditions, and the method was specific for determination of perindopril and indapamide in the presence of degradation products. The method was validated in terms of linearity, precision, accuracy, specificity, robustness, and solution stability. The linearity of the proposed method was investigated in the range of 24-56 microg/mL (r2 = 0.9993) for perindopril and 7.5-17.5 microg/mL (r2 = 0.9992) for indapamide. Degradation products produced as a result of stress studies did not interfere with the detection of perindopril and indapamide, and the assay can thus be considered stability indicating. PMID:20334172

Jogia, Hitesh; Khandelwal, Umesh; Gandhi, Tripti; Singh, Sukhdev; Modi, Darshana

2010-01-01

369

Development and validation of a stability indicating method for seven novel derivatives of lamivudine with anti-HIV and anti-HBV activity in simulated gastric and intestinal fluids.  

PubMed

A simple micellar liquid chromatography (MLC) method has been developed and validated for use in stability indicating studies of lamivudine and its carbonate derivatives with proved activity against human immunodeficiency and hepatitis B viruses (HIV and HBV, respectively), in simulated gastric (SGF) and intestinal (SIF) fluids samples. The optimized method involves a C18 column thermostated at 30°C, UV detection at 272 nm, a flow rate of 1.0 mL min(-1) and a micellar mobile phase composed by 0.15M sodium dodecyl sulphate (SDS) - 4% (v/v) 1-butanol - 0.01 M KH2PO4-Na2HPO4 (pH 7), using zidovudine (AZT) as internal standard. Validation under Food and Drug Administration (FDA) guideline of the analytical parameters include: linearity (r(2)>0.9996), LODs (1.6 × 10(-7)-6.9 × 10(-6)M) and LOQ (1 × 10(-5)M), intra (0.02-1.48%) and inter-day precision (0.04-1.66%) expressed as relative standard deviation (R.S.D.), and robustness parameters (less than 1.98%). Using this method, recoveries ranging from 92.9 to 119% were obtained for the eight substances. Thus, this method provides a simple, sensitive, accurate and precise assay for the determination of all compounds that can be readily adaptable to routine use by clinical laboratories with standard equipment. In addition, we evaluated the stability of carbonates of lamivudine in buffer pH 1.2 and 6.8; SGF (pH 1.2) and SIF one (pH 6.8), all as indicated in United States Pharmacopeia (USP) 32. Finally, this chromatographic method was applied to stability studies which resulted in all the compounds following a pseudo-first-order kinetics, and in the determination of its kinetic constant and half-life time. PMID:23454677

Gualdesi, María S; Esteve-Romero, Josep; Briñón, Margarita C; Raviolo, Mónica A

2013-05-01

370

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

PubMed Central

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

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

2012-01-01

371

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

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

Prakash, Lakkireddy; Malipeddi, H; Venkata Subbaiah, B; Lakka, Narasimha S

2015-01-01

372

Complexity in Estimation of Esomeprazole and its Related Impurities’ Stability in Various Stress Conditions in Low-Dose Aspirin and Esomeprazole Magnesium Capsules  

PubMed Central

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

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

2013-01-01

373

Stability and Feedback Stabilization 1639 Stability and Feedback Stabilization  

E-print Network

Stability and Feedback Stabilization 1639 Stability and Feedback Stabilization EDUARDO D. SONTAG Sensitivity to Small Measurement Errors Future Directions Bibliography Glossary Stability A globally, with no large excursions. Stabilization A system is stabilizable (with respect to a given state

Sontag, Eduardo

374

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 ...

375

Antioxidant activities and phenolic composition of extracts from Greek oregano, Greek sage, and summer savory.  

PubMed

Oregano vulgare L. ssp. hirtum (Greek oregano), Salvia fruticosa (Greek sage), and Satureja hortensis (summer savory) were examined as potential sources of phenolic antioxidant compounds. The antioxidant capacities (antiradical activity by DPPH* test, phosphatidylcholine liposome oxidation, Rancimat test) and total phenol content were determined in the ethanol and acetone extracts of the dried material obtained from the botanically characterized plants. The ground material was also tested by the Rancimat test for its effect on the stability of sunflower oil. The data indicated that ground material and both ethanol and acetone extracts had antioxidant activity. Chromatographic (TLC, RP-HPLC) and NMR procedures were employed to cross-validate the presence of antioxidants in ethanol and acetone extracts. The major component of all ethanol extracts was rosmarinic acid as determined by RP-HPLC and NMR. Chromatography indicated the presence of other phenolic antioxidants, mainly found in the acetone extracts. The presence of the flavones luteolin and apigenin and the flavonol quercetin was confirmed in the majority of the extracts by the use of a novel (1)H NMR procedure, which is based on the strongly deshielded OH protons in the region of 12-13 ppm without previous chromatographic separation. This deshielding may be attributed to the strong intramolecular six-membered ring hydrogen bond of the OH(5)...CO(4) moiety. PMID:12207464

Exarchou, V; Nenadis, N; Tsimidou, M; Gerothanassis, I P; Troganis, A; Boskou, D

2002-09-11

376

Comparison of Procedures for Resveratrol Analysis in Beer: Assessment of Stilbenoids Stability through Wort Fermentation and Beer Aging  

Microsoft Academic Search

J. Inst. Brew. 114(2), 143-149, 2008 Three resveratrol extraction procedures were compared in beer. Two-step pre-cleaning with toluene and cyclohexane allows 76% trans-resveratrol recovery by solid-phase extraction (SPE) be- fore RP-HPLC-MS\\/MS analysis. This procedure proved much more efficient than liquid\\/liquid extraction, which requires sol- vents that are too hydrophobic for stilbenoids. SPME-GC-MS, where the main limiting factor is non-reproducibility from

Vesna Jerkovic; Fanny Nguyen; Aurore Timmermans; Sonia Collin

377

Social Indicators  

NSDL National Science Digital Library

The House of Commons Library Research Papers are published for the benefit of Parliament members, but this one should be of interest to both researchers and general readers wanting to learn more about contemporary British social issues. Social Indicators is the first paper in a new series that will be published three times a year. The 71-page paper includes a wide range of topic pages that present social statistics on a variety of issues, from the prison population to defense expenses to agricultural outputs. Each Social Indicator paper will also offer feature articles that give a closer look at specific subjects (in this instance,, election turnout and adult literacy) and an article on statistical sources for a particular issue (in this paper, social security statistics). The last few pages are devoted to a list of important, recent governmental statistical publications.

Bolton, Paul.

2001-01-01

378

Validated stability-indicating high-performance thin-layer chromatographic method for estimation of cefpodoxime proxetil in bulk and in pharmaceutical formulation according to International conference on harmonization guidelines  

PubMed Central

Aim: A simple, selective, precise, and stability-indicating high-performance thin-layer chromatographic (HPTLC) method for analysis of cefpodoxime proxetil both in bulk and in pharmaceutical formulation has been developed and validated. Materials and Methods: The method employed HPTLC aluminum plates precoated with silica gel 60 RP-18 F254 as the stationary phase. The solvent system consisted of toluene:methanol:chloroform (4:2:4 v/v). The system was found to give compact spot for cefpodoxime proxetil (Rf value of 0.55 ± 0.02). Densitometric analysis of cefpodoxime proxetil was carried out in the absorbance mode at 289 nm. Results: The linear regression analysis data for the calibration plots showed good linear relationship, with r2 = 0.998 ± 0.0015 with respect to peak area in the concentration range of 100–600 ng per spot. The mean value±SD of slope and intercept were 3.38 ± 1.47 and 986.9 ± 108.78 with respect to peak area. The method was validated for precision, recovery, and robustness. The limits of detection and quantification were 3.99 and 12.39 ng per spot, respectively. Cefpodoxime proxetil was subjected to acid and alkali hydrolysis, oxidation, and thermal degradation. The drug undergoes degradation under acidic and basic conditions, indicating that the drug is susceptible to both acid and base. The degraded product was well resolved from the pure drug, with significantly different Rf value. Statistical analysis proves that the method is repeatable, selective, and accurate for the estimation of the investigated drug. Conclusion: The proposed HPTLC method can be applied for identification and quantitative determination of cefpodoxime proxetil in both bulk drug and pharmaceutical formulation. PMID:22557919

Jain, Pritam; Chaudhari, Amar; Bang, Anup; Surana, Sanjay

2012-01-01

379

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

PubMed

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

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

2014-06-01

380

TWO RP-HPLC METHODS TO QUANTIFY AND IDENTIFY BISPHENOL A DIGLYCIDYL ETHER (BADGE): EUROPEAN UNION FATTY FOOD SIMULANT (OLIVE OIL) DOS MÉTODOS RP-HPLC PARA CUANTIFICAR E IDENTIFICAR BISFENOL A DIGLICIDIL ÉTER (BADGE): SIMULANTE DE ALIMENTOS GRASOS DE LA UNIÓN EUROPEA (ACEITE DE OLIVA) DOUS MÉTODOS RP-HPLC PARA CUANTIFICAR E IDENTIFICAR BISFENOL A DIGLICIDIL ÉTER (BADGE): SIMULANTE DE ALIMENTOS GRASOS DA UNIÓN EUROPEA (ACEITE DE OLIVA)  

Microsoft Academic Search

Two HPLC-UV methods with fluorescence detection have been applied to quantify and identify bisphenol A diglycidyl ether (BADGE: a monomer of epoxy resins used as a coating in packaging materials that contact food), in olive oil (official fatty food simulant in European Union legislation) and in food coatings. Through an extraction process in solid phase employing a Florisil cartridge, BADGE

P. Paseiro-Losada; M. F. López-Fabal; C. Pérez-Lamela; P. Sanmartín-Fenollera; S. Paz-Abuín

1999-01-01

381

Simultaneous RP-HPLC determination of sotalol, metoprolol, alpha-hydroxymetoprolol, paracetamol and its glucuronide and sulfate metabolites in human urine.  

PubMed

The HPLC method for the determination of sotalol (SOT), metoprolol (MET) and alpha-hydroxymetoprolol metabolite (MET-H), paracetamol (PAR), paracetamol glucuronide (PAR-G) and paracetamol sulfate (PAR-S) in human urine is described. Analyses were carried out on a reversed-phase LiChroCART Purospher C18e column (125 mm x 3 mm, 5 microm particles) (Merck) with gradient elution as well as spectrophotometric and fluorometric detection. Good resolution of the analyzed substances was obtained within a time range of no longer than 15 min. The linearity ranges of the callibration curves in human urine (as matrix) were: 3.25-45 microg ml(-1) (SOT), 0.75-40 microg ml(-1) (MET), 0.6-40 microg ml(-1) (MET-H), 4.6-60 microg ml(-1) (PAR-G), 4.95-50 microg ml(-1) (PAR-S), 1.95-45 microg ml(-1) (PAR). An application to human urine samples was performed. PMID:19531885

Baranowska, Irena; Wilczek, Andrzej

2009-06-01

382

RP-HPLC method using 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate incorporated with normalization technique in principal component analysis to differentiate the bovine, porcine and fish gelatins.  

PubMed

The amino acid compositions of bovine, porcine and fish gelatin were determined by amino acid analysis using 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate as derivatization reagent. Sixteen amino acids were identified with similar spectral chromatograms. Data pre-treatment via centering and transformation of data by normalization were performed to provide data that are more suitable for analysis and easier to be interpreted. Principal component analysis (PCA) transformed the original data matrix into a number of principal components (PCs). Three principal components (PCs) described 96.5% of the total variance, and 2 PCs (91%) explained the highest variances. The PCA model demonstrated the relationships among amino acids in the correlation loadings plot to the group of gelatins in the scores plot. Fish gelatin was correlated to threonine, serine and methionine on the positive side of PC1; bovine gelatin was correlated to the non-polar side chains amino acids that were proline, hydroxyproline, leucine, isoleucine and valine on the negative side of PC1 and porcine gelatin was correlated to the polar side chains amino acids that were aspartate, glutamic acid, lysine and tyrosine on the negative side of PC2. Verification on the database using 12 samples from commercial products gelatin-based had confirmed the grouping patterns and the variables correlations. Therefore, this quantitative method is very useful as a screening method to determine gelatin from various sources. PMID:25442566

Azilawati, M I; Hashim, D M; Jamilah, B; Amin, I

2015-04-01

383

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

PubMed

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

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

2014-06-01

384

A simple reversed phase high-performance liquid chromatography (RP-HPLC) method for determination of curcumin in aqueous humor of rabbit  

PubMed Central

This article describes a simple and rapid method for determination of curcumin (diferuloylmethane) in aqueous humor of rabbit using high-performance liquid chromatography (HPLC). Analysis was performed using a C-18 column (250 × 4.6 mm, 5 ? luna) by isocratic elution with a mobile phase containing 25 mM potassium dihydrogen orthophosphate (pH 3.5): Acetonitrile (40:60) and detection at 424 nm using a photodiode array (PDA) detector for curcumin. The regression data for curcumin showed a good linear relationship with r2> 0.998 over the concentration range of 0.1-10 ?g ml?1. Relative standard deviations (RSD) for the intraday and interday coefficient of variations for the assay were less than 5.0 and 8.5, respectively. The recovery of the method was between 79.8-83.6%. The quantification limit of the method for curcumin was 0.01 ?g ml?1. This method has good accuracy, precision, and quantitation limit. It is also concluded that the method is useful for measuring very low curcumin concentrations in aqueous humor. PMID:25126537

Mishra, Akhilesh; Dewangan, Gayatri; Singh, W Ramdas; Hazra, Sarbani; Mandal, Tapan Kumar

2014-01-01

385

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

PubMed Central

The aim of the present work was to develop and validate a reversed-phase high-performance liquid chromatography method for the simultaneous estimation of picroside I, plumbagin, and Z-guggulsterone in a polyherbal formulation containing Picrorhiza kurroa, Plumbago zeylanica, and Commiphora wightii extracts. The analysis was performed on a C18 column using the mobile phase consisting of solvent A (acetonitrile) and solvent B (0.1% orthophosphoric acid in water) with the following gradient: 0-12 min, 25% A; 12-17 min, 25-80% A; 17-32 min, 80% A; and 32-37 min, 80-25% A at a flow rate of 1 ml/min. Ultraviolet detection was at 255 nm. The method was validated for accuracy, precision, linearity, specificity, and sensitivity as per the norms of the International Conference on Harmonization. From the validation study, it was found that the method is specific, accurate, precise, reliable, and reproducible. Good linear correlation coefficients (r2>0.900) were obtained for calibration plots in the ranges tested. Limits of detection were 2.700, 0.090 and 0.099 ?g/ml and limits of quantification were 9.003, 0.310, and 0.330 ?g/ml for picroside I, plumbagin, and Z-guggulsterone, respectively. Intra and interday relative standard deviation (RSD) of retention times and peak areas was less than 3.0%. Recovery was found to be 100.21% for picroside I, 102.5% for plumbagin, and 103.84% for Z-guggulsterone. The established method was appropriate and the three markers were well resolved, enabling efficient quantitative analysis of picroside I, plumbagin and Z-guggulsterone. The method is a rapid and cost-effective quality control tool for routine quantitative analysis of picroside I, plumbagin, and Z-guggulsterone in tablet dosage form. PMID:24302803

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

2013-01-01

386

DEVELOPMENT AND VALIDATION OF AN RP-HPLC METHOD FOR THE DETERMINATION OF CHLORHEXIDINE AND P-CHLOROANILINE IN VARIOUS PHARMACEUTICAL FORMULATIONS  

Microsoft Academic Search

? A simple, rapid and sensitive isocratic reversed-phase (RP) high-performance liquid chromatography (HPLC) method was developed and validated for the simultaneous determination of chlorhexidine (CHX) and p-chloroaniline (CAL) in various pharmaceutical formulations. Compound separation was achieved in less than 10 min with an XBridge C18 column that was maintained at 40°C and a mobile phase consisting of 32:68 (v\\/v) of acetonitrile

Marco A. Cardoso; Maria L. D. Fávero; João C. Gasparetto; Bianca S. Hess; Dile P. Stremel; Roberto Pontarolo

2011-01-01

387

Haemagglutinin quantification and identification of influenza A&B strains propagated in PER.C6 ® cells: A novel RP-HPLC method  

Microsoft Academic Search

The major antigenic determinant of influenza A and B virus is haemagglutinin (HA). The HA content is an important specification of influenza vaccines. HA in vaccines has typically been quantified by single-radial-immunodiffusion (SRID). However, SRID is a laborious and low throughput assay. Moreover, sensitivity, accuracy, and precision, especially for non-purified (in-process) influenza virus is relatively low. We present a novel

Johan C. Kapteyn; Mohammed Drissi Saidi; René Dijkstra; Cennet Kars; Joan C. M. S. K. Tjon; G. J. Weverling; Marcel L. de Vocht; Ronald Kompier; Bart A. van Montfort; Jean-Yves Guichoux; Jaap Goudsmit; Fija M. Lagerwerf

2006-01-01

388

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

PubMed Central

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

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

2012-01-01

389

RP-HPLC METHOD FOR SIMULTANEOUS ESTIMATION OF ATORVASTATIN CALCIUM, LOSARTAN POTASSIUM, ATENOLOL, AND ASPIRIN FROM TABLET DOSAGE FORM AND PLASMA  

Microsoft Academic Search

A rapid, simple, sensitive, and selective chromatographic method has been developed for the simultaneous estimation of atorvastatin calcium, losartan potassium, atenolol, and aspirin in marketed formulation. The separation was carried out on a KYA TECH HiQ Sil C18HS (250 × 4.6 mm i.d., 5 µm particle size) column using a mobile phase of acetonitrile: 0.02 M potassium dihydrogen phosphate buffer (pH 3.4) (70:30% v\\/v). The

Neela M. Bhatia; Sachin B. Gurav; Swapnil D. Jadhav; Manish S. Bhatia

2012-01-01

390

A simple reversed phase high-performance liquid chromatography (RP-HPLC) method for determination of curcumin in aqueous humor of rabbit.  

PubMed

This article describes a simple and rapid method for determination of curcumin (diferuloylmethane) in aqueous humor of rabbit using high-performance liquid chromatography (HPLC). Analysis was performed using a C-18 column (250 × 4.6 mm, 5 ? luna) by isocratic elution with a mobile phase containing 25 mM potassium dihydrogen orthophosphate (pH 3.5): Acetonitrile (40:60) and detection at 424 nm using a photodiode array (PDA) detector for curcumin. The regression data for curcumin showed a good linear relationship with r(2)> 0.998 over the concentration range of 0.1-10 ?g ml(-1). Relative standard deviations (RSD) for the intraday and interday coefficient of variations for the assay were less than 5.0 and 8.5, respectively. The recovery of the method was between 79.8-83.6%. The quantification limit of the method for curcumin was 0.01 ?g ml(-1). This method has good accuracy, precision, and quantitation limit. It is also concluded that the method is useful for measuring very low curcumin concentrations in aqueous humor. PMID:25126537

Mishra, Akhilesh; Dewangan, Gayatri; Singh, W Ramdas; Hazra, Sarbani; Mandal, Tapan Kumar

2014-07-01

391

Development and Validation of a RP-HPLC Method for Estimation of Montelukast Sodium in Bulk and in Tablet Dosage Form  

PubMed Central

The present work describes a simple, precise and accurate HPLC method for estimation of montelukast sodium in bulk and in tablet dosage form. The separation was achieved by using octadecylsilane column (C18) and acetonitrile:1 mM sodium acetate adjusted to pH 6.3 with acetic acid in proportion of 90:10 v/v as mobile phase, at a flow rate of 1.5 ml/min. Detection was carried out at 285 nm. The retention time of montelukast sodium was found to be 3.4 min. The limit of detection was found 1.31 µg/ml and limit of quantification 3.97 µg/ml. The accuracy and reliability of the proposed method was ascertained by evaluating various validation parameters like linearity (1-100 µg/ml), precision, accuracy and specificity according to ICH guidelines. The proposed method provides an accurate and precise quality control tool for routine analysis of montelukast sodium in bulk and in tablet dosage form. PMID:20838530

Singh, R. M.; Saini, P. K.; Mathur, S. C.; Singh, G. N.; Lal, B.

2010-01-01

392

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

PubMed

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

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

2013-07-01

393

Development and Validation of a RP-HPLC Method for the Simultaneous Determination of Aceglutamide and Oxiracetam in an Injection Formulation.  

PubMed

This paper describes a rapid method to determine aceglutamide (ACE) and oxiracetam (OXI) present in an injection formulation using reversed-phase high-performance liquid chromatography. The method was validated with respect to suitability, linearity, accuracy, precision and robustness. Chromatography was carried out on an Elite SinoChrom ODS-BP C18 (5 ?m, 250 × 4.60 mm) column with an isocratic mobile phase composed of methanol-phosphate buffer (pH 3.0) in the ratio of 5:95, v/v, at a flow rate of 1.0 mL/min. Detection was carried out using a UV-PDA detector at 210 nm. The linearity range for ACE and OXI were 10-500 and 10-300 ?g/mL, respectively. The relative standard deviations for replicate measurements were always <2%. PMID:25238766

Wang, Dandan; Wu, Shengde

2014-09-19

394

Validated RP-HPLC/UV method for the quantitation of abiraterone in rat plasma and its application to a pharmacokinetic study in rats.  

PubMed

A novel, simple, specific, sensitive and reproducible high-performance liquid chromatography (HPLC) assay method has been developed and validated for the estimation of abiraterone (ART) in rat plasma. The analytical procedure involves extraction of ART and diclofenac (internal standard, IS) from rat plasma with a simple liquid-liquid extraction process. The chromatographic analysis was performed on a Waters Alliance system with a Betasil C(18) column maintained at ambient room temperature and an isocratic mobile phase [acetonitrile-water-10 mm potassium dihydrogen phosphate (pH 3.0), 55:5:40, v/v/v] at a flow rate of 1.00 mL/min with a total run time of 10 min. The eluate was monitored using an UV detector set at 255 nm. Method validation was performed as per FDA guidelines and the results met the acceptance criteria. The calibration curve was linear over a concentration range of 93.4-3251 ng/mL (r(2) = 0.997). The intra- and inter-day precisions were 0.56-4.98 and 3.03-7.18, respectively, in rat plasma. The validated HPLC method was successfully applied to a pharmacokinetic study of ART in rats. PMID:22763809

Kumar, S Vijay; Rudresha, G; Gurav, Sandip; Zainuddin, Mohd; Dewang, Purushottam; Kethiri, Raghava Reddy; Rajagopal, Sriram; Mullangi, Ramesh

2013-02-01

395

[Study on establishment of RP-HPLC and GC-MS fingerprints for wild germplasm resource of Ophiopogon japonicus in Sichuan and hierarchical clustering analysis].  

PubMed

The chromatographic fingerprint was established for evaluating and controlling the quality of germplasm resource of Ophiopogon japonicus in Sichuan Basin by reversed-phase high performance liquid chromatography and gas chromatography mass spectrometry. The results showed that each sample the characterized by the peak area of 28 HPLC peaks and 13 GC peaks in each program and these peaks were employed for hierarchical cluster analysis. Furthermore, the discrimination of the sample from different regions was achieved by hierarchical cluster analysis via recognizing the 16 (41 datamatrix. This was the first report of hierarchical cluster analysis of the wild germplasm resource of Ophiopogon japonicus according to their chemical fingerprints. Thus, the results proved it is a simple, rapid and accurate method suitable for the quality control of the traditional Chinese medicines. PMID:21246828

Liu, Jiang; Chen, Xingfu; Yang, Wenyu; Liu, Weiguo; Jiang, Tao

2010-10-01

396

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

PubMed

A novel highly sensitive ion-pairing reversed-phase high performance liquid-chromatography/electrochemical detection method for simultaneous determination of L -ascorbic acid, aminothiols, and methionine in biological matrices is presented. Reduced forms of the analytes are extracted from sample matrices with 10% m-phosphoric acid solution(aqueous). To determine the total vitamin C, the total aminothiols, and the total methionine, samples are treated with tris(2-carboxyethyl)phosphine solution in 0.05% trifluoroacetic acid solution(aqueous) subsequent to deproteination to reduce the oxidized forms of these compounds. Various analytes are separated on a C18 (250?×?4.6 mm, 5 ?m) analytical column using methanol-0.05% trifluoroacetic acid solution(aqueous) (05:95 v/v, containing 0.1 mM 1-octane sulfonic acid as the ion-pairing agent) as the isocratic mobile phase that is pumped at a flow rate of 1.5 ml/min at room temperature. The column eluents are monitored at a voltage of 0.85 V. These analytes are efficiently resolved in less than 20 min using n-acetyl cysteine as the internal standard. PMID:25323509

Khan, Muhammad Imran; Iqbal, Zafar; Khan, Abad

2015-01-01

397

Simultaneous determination of the endogenous free ?-lipoic acid and dihydrolipoic acid in human plasma and erythrocytes by RP-HPLC coupled with electrochemical detector.  

PubMed

A highly sensitive, precise, and accurate reversed-phase high performance liquid-chromatography/electrochemical detection method for simultaneous determination of the endogenous free ?-lipoic acid and dihydrolipoic acid in biological matrices is presented. The two analytes are extracted from samples with acetonitrile-10% m-phosphoric acid solution(aqueous) (50:50 v/v). To determine the total lipoic acid, samples are treated with tris(2-carboxyethyl)phosphine solution in phosphate buffer: pH 2.5 with 85% o-phosphoric acid prior to deproteination. The two analytes are separated on a C18 (150?×?4.6 mm, 5 ?m) analytical column using acetonitrile-50 mM phosphate buffer: pH 2.5 with 85% o-phosphoric acid (35:65 v/v) as the isocratic mobile phase pumped at a flow rate of 2.0 ml/min at the column oven temperature of 35 °C. The column eluents are monitored at a potential of 0.9 V. These analytes are efficiently resolved in <7 min. PMID:25323519

Khan, Muhammad Imran; Iqbal, Zafar; Khan, Abad

2015-01-01

398

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  

Microsoft Academic Search

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

Bedrossian

1980-01-01

399

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

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.

Bedrossian, T.L.

1980-01-01

400

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

PubMed Central

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

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

2008-01-01

401

Slope stability and stabilization methods  

SciTech Connect

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.

Abramson, L.W.; Lee, T.S.; Boyce, G.M.; Sharma, S.S.

1995-12-01

402

Torsion--treatment indications.  

PubMed

Rotational problems, when outside the normal range, are referred to as torsional deformity. These deformities are relatively common in infancy and childhood, generally resolve spontaneously with growth, and rarely persist into adult life. There are few situations in which treatment is necessary. (1) Rigid metatarsus adductus that does not resolve during the first six months should be corrected by casting. The long leg cast is most effective, as it controls the rotation of the tibia. With the tibia stabilized, the foot can be laterally rotated and abducted, which usually allows correction using one or two casts. (2) Persistent, severe tibial medial or lateral torsion after the age of eight years may be corrected by a supramalleolar tibial rotational osteotomy. This is indicated for medial torsion beyond 15 degrees and for lateral torsion beyond 30 degrees. Fixation is provided by crossed, smooth pins and a long leg cast. Compartment syndromes and peroneal nerve injury are avoided by the distal correction. (3) Persistent, severe femoral antetorsion of more than 50 degrees after the age of eight years may justify correction. For operative correction, medial rotation should exceed 85 degrees and lateral rotation should be less than 10 degrees. The osteotomy for correction is fixed by threaded Steinmann pins cut off below the skin and supplemented with a spica cast. PMID:2676305

Staheli, L T

1989-10-01

403

Influence of plant growth stage and season on the release of root phenolics by mulberry as related to development of phytoremediation technology  

Microsoft Academic Search

The phenolics released by red mulberry (Morus rubra L.) roots at different growth stages within a season were quantified and the makeup of phenols analyzed by reverse-phase high performance liquid chromatography (RP-HPLC). The data show that total phenols released into the soil solution increased continuously from an early vegetative stage to leaf senescence, indicating their accumulation in the rhizosphere. From

Ramesh S. Hegde; John S. Fletcher

1996-01-01

404

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...

405

Membrane stabilizer  

SciTech Connect

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.

Mingenbach, William A. (P.O. Box 49, Taos, NM 87571)

1988-01-01

406

ECOLOGICAL PERFORMANCE INDICATORS  

EPA Science Inventory

EMAP has traditionally relied on indicators of ecological condition to report on the extent to which coastal waters are impaired. Correlations between biological indicators and physical or chemical indicators may generate hypotheses about potential causes of impairment but are n...

407

Thermal indicator for wells  

DOEpatents

Minute durable plate-like thermal indicators are employed for precision measuring static and dynamic temperatures of well drilling fluids. The indicators are small enough and sufficiently durable to be circulated in the well with drilling fluids during the drilling operation. The indicators include a heat resistant indicating layer, a coacting meltable solid component and a retainer body which serves to unitize each indicator and which may carry permanent indicator identifying indicia. The indicators are recovered from the drilling fluid at ground level by known techniques.

Gaven, Jr., Joseph V. (Oakton, VA); Bak, Chan S. (Newbury Park, CA)

1983-01-01

408

Purification and identification of dipeptidyl peptidase (DPP) IV inhibitory peptides from the macroalga Palmaria palmata.  

PubMed

Dipeptidyl peptidase (DPP)-IV inhibitory peptides were purified and identified from an aqueous Palmaria palmata protein extract hydrolysed with Corolase PP. The hydrolysate was fractionated by solid phase extraction (SPE) using a C18 matrix followed by semi-preparative reverse phase-high performance liquid chromatography (SP RP-HPLC). IC50 values of 1.47 ± 0.09, 0.54 ± 0.03 and 0.36 ± 0.03 mg/ml were obtained for the hydrolysate, the 25%--acetonitrile (ACN) SPE fraction and the most active SP RP-HPLC peptide fraction (SP RP-HPLC 25_F28), respectively. Thirteen peptide sequences were identified following UPLC-ESI MS/MS analysis of SP RP-HPLC 25_F28. Three novel DPP-IV inhibitory peptides, Ile-Leu-Ala-Pro, Leu-Leu-Ala-Pro and Met-Ala-Gly-Val-Asp-His-Ile, with IC50 values in the range 43-159 ?M were identified. The results indicate that P. palmata derived peptides may have potential as functional food ingredients in the prevention and management of type 2 diabetes. PMID:25442570

Harnedy, Pádraigín A; O'Keeffe, Martina B; FitzGerald, Richard J

2015-04-01

409

DNA Sequences Shaped by Selection for Stability  

E-print Network

DNA Sequences Shaped by Selection for Stability Martin Ackermann1,2* , Lin Chao1 1 Division for an important determinant of stability, the presence of mononucleotide repeats. We find that codons are used this bias to selection rather than a neutral process. This indicates that selection for stability, rather

Ackermann, Martin

410

A Validated Stability-Indicating LC Method for Zonisamide  

Microsoft Academic Search

A simple, isocratic, rapid, and accurate reversed-phase high-performance liquid chromatographic method has been established\\u000a for quantitative determination of zonisamide. The method is also applicable to determination of related substances in the\\u000a bulk drug. Chromatographic separation was achieved on a 250 mm ? 4.6 mm, 5-?m particle, C18 column; the mobile phase was a 70:30 (v\\/v) mixture of 0.1% (v\\/v) aqueous triethylamine, adjusted to pH

Dnyandeo B. Pathare; Ashok S. Jadhav; Murlidhar S. Shingare

2007-01-01

411

A Validated Stability Indicating RPLC Method for Tazarotene  

Microsoft Academic Search

A simple, isocratic, rapid and accurate reversed phase high performance liquid chromatography method was developed for the\\u000a quantitative determination of tazarotene. The developed method is also applicable for the related substance determination\\u000a in bulk drugs. The chromatographic separation was achieved on a Hypersil C18 (250 mm ? 4.6 mm 5 ?m) column using water pH\\u000a 2.5 with orthophosphoric acid:acetonitrile (15:85, v\\/v) as a mobile phase.

D. B. Pathare; A. S. Jadhav; M. S. Shingare

2007-01-01

412

Environmental Treaties and Indicators Resource Indicators  

NSDL National Science Digital Library

ENTRI is an international, collaborative effort hosted by the Consortium for International Earth Science Information Network (CIESIN) charged with providing "information about environmental treaties and national resource indicators." These treaties are organized into nine issue areas which cover land use change and desertification, transboundary air pollution, and trade and the environment, among others. Treaties can be searched or browsed. Free text searching of the treaties and treaty summaries is also available.

413

Slope Stability  

NSDL National Science Digital Library

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

414

SRR Ecological Assessment Indicators: Selection and  

E-print Network

of Wyoming Dr. John Mitchell USDA Forest Service #12;Ranch Assessment Indicators · Soils - Bare soil cover, Soil aggregate stability · Water - Surface water frequency, Volume · Plants - Key species, Invasives and habitat for organisms #12;SOIL -General Approach · Pertinent to watershed values, runoff, erosion

Wyoming, University of

415

Fluid leak indicator  

NASA Technical Reports Server (NTRS)

A fluid leak indicator (30) for detecting and indicating leaks in visually inaccessible fluid tubing joints (20, 21), such as those obstructed by insulation (24), includes a bag system (25) and a wicking system (30) surrounding or wrapping the joints (20, 21) under the visual obstructing material (24). Leaking fluid is collected in the bag (25) or on the wicking material (34) where it is conducted along the wicking material (34) to a visibly accessible capturing transparent indicator bulb (35) for providing a visual indication of the leak without requiring a chemical change in the capturing indicator bulb (35).

Anderson, George E. (Inventor); Loo, Shu (Inventor)

1989-01-01

416

Fluid leak indicator  

NASA Technical Reports Server (NTRS)

A fluid leak indicator for detecting and indicating leaks in visually inaccessible fluid tubing joints, such as those obstructed by insulation includes a bag system and a wicking system surrounding or wrapping the joints under the visual obstructing material. Leaking fluid is collected in the bag or on the wicking material where it is conducted along the wicking material to a visily accessible capturing transparent indicator bulb for providing a visual indication of the leak without requiring a chemical change in the capturing indicator bulb.

Anderson, G. E.; Loo, S. (inventors)

1985-01-01

417

Stability, Pole Placement, Observers and Stabilization  

E-print Network

Stability, Pole Placement, Observers and Stabilization H.L. Trentelman1 1University of Groningen, The Netherlands DISC Course Mathematical Models of Systems H.L. Trentelman University of Groningen Stability, Pole Placement, Observers and Stabilization #12;Stability of autonomous Systems Autonomous systems Let P() Rq

Vellekoop, Michel

418

Stability analysis of Newtonian polytropes  

E-print Network

We analyze the stability of Newtonian polytropic static fluid spheres, described by the Lane-Emden equation. In the general case of arbitrary polytropic indices the Lane-Emden equation is a non-linear second order ordinary differential equation. By introducing a set of new variables, the Lane-Emden equation can be reduced to an autonomous system of two ordinary differential equations, which in turn may be transformed to another regular second order differential equation. We perform the study of stability by using linear stability analysis, the Jacobi stability analysis (Kosambi-Cartan-Chern theory) and the Lyapunov function method. Depending on the values of the polytropic index characterizing the fluid, these different methods yield different qualitative results on the stability of the solutions. On the other hand, these techniques offer a powerful method for constraining the physical properties of the Newtonian stars.

Boehmer, Christian G

2009-01-01

419

Indicators of Quality.  

ERIC Educational Resources Information Center

Surveyed students, faculty, administrative staff, governing board, and employers affiliated with a public two-year college to determine their perceptions of various quality indicators and congruence between the groups. Found that all groups placed importance on indicators of customer satisfaction and skill development; beyond that, considerable…

Cleary, Thomas S.

2001-01-01

420

School Readiness Indicator Items.  

ERIC Educational Resources Information Center

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…

Calkins, Julia; Ling, Thomson; Moore, Eric; Halle, Tamara; Hair, Beth; Moore, Kris; Zaslow, Marty

421

Cobb's Red Cabbage Indicator.  

ERIC Educational Resources Information Center

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)

Cobb, Vicki

1998-01-01

422

Quality Indicator System Report.  

ERIC Educational Resources Information Center

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

Colorado Commission on Higher Education, Denver.

423

General Indicators: Performance Statistics  

E-print Network

General Indicators: Performance Statistics Current Month Change from Previous Month Recent Trend for descriptions of performance measures and specific color code target values. Trend status color indicators Initial Target St. Paul - West Health Science East Bank Central Svcs. Energy Mgmt Admin Safety: Lost Time

Webb, Peter

424

General Indicators: Performance Statistics  

E-print Network

General Indicators: Performance Statistics Current Month Change from Previous Month Recent Trend of performance measures and specific color code target values. Trend status color indicators ­ identifies changes Initial Target St. Paul - West Health Science East Bank Central Svcs. Energy Mgmt Admin Safety: Lost Time

Webb, Peter

425

Cabbage Juice Indicator  

NSDL National Science Digital Library

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