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papers from the latest issue:
Improving the efficiency of quantitative 1H NMR: An innovative external standard–internal reference approach
21 October 2013,
01:15:21
Publication date: 25 January
2014
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 88
Author(s): Yande Huang , Bao-Ning Su , Qingmei Ye , Venkatapuram A. Palaniswamy , Mark S. Bolgar , Thomas V. Raglione
The classical internal standard quantitative NMR (qNMR) method determines the purity of an analyte by the determination of a solution containing the analyte and a standard. Therefore, the standard must meet the requirements of chemical compatibility and lack of resonance interference with the analyte as well as a known purity. The identification of such a standard can be time consuming and must be repeated for each analyte. In contrast, the external standard qNMR method utilizes a standard with a known purity to calibrate the NMR instrument. The external standard and the analyte are measured separately, thereby eliminating the matter of chemical compatibility and resonance interference between the standard and the analyte. However, the instrumental factors, including the quality of NMR tubes, must be kept the same. Any deviations will compromise the accuracy of the results. An innovative qNMR method reported herein utilizes an internal reference substance along with an external standard to assume the role of the standard used in the traditional internal standard qNMR method. In this new method, the internal reference substance must only be chemically compatible and be free of resonance-interference with the analyte or external standard whereas the external standard must only be of a known purity. The exact purity or concentration of the internal reference substance is not required as long as the same quantity is added to the external standard and the analyte. The new method reduces the burden of searching for an appropriate standard for each analyte significantly. Therefore the efficiency of the qNMR purity assay increases while the precision of the internal standard method is retained.
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 88
Author(s): Yande Huang , Bao-Ning Su , Qingmei Ye , Venkatapuram A. Palaniswamy , Mark S. Bolgar , Thomas V. Raglione
The classical internal standard quantitative NMR (qNMR) method determines the purity of an analyte by the determination of a solution containing the analyte and a standard. Therefore, the standard must meet the requirements of chemical compatibility and lack of resonance interference with the analyte as well as a known purity. The identification of such a standard can be time consuming and must be repeated for each analyte. In contrast, the external standard qNMR method utilizes a standard with a known purity to calibrate the NMR instrument. The external standard and the analyte are measured separately, thereby eliminating the matter of chemical compatibility and resonance interference between the standard and the analyte. However, the instrumental factors, including the quality of NMR tubes, must be kept the same. Any deviations will compromise the accuracy of the results. An innovative qNMR method reported herein utilizes an internal reference substance along with an external standard to assume the role of the standard used in the traditional internal standard qNMR method. In this new method, the internal reference substance must only be chemically compatible and be free of resonance-interference with the analyte or external standard whereas the external standard must only be of a known purity. The exact purity or concentration of the internal reference substance is not required as long as the same quantity is added to the external standard and the analyte. The new method reduces the burden of searching for an appropriate standard for each analyte significantly. Therefore the efficiency of the qNMR purity assay increases while the precision of the internal standard method is retained.
Graphical abstract
Combined HPLC-DAD–MS, HPLC–MSn and NMR spectroscopy for quality control of plant extracts: The case of a commercial blend sold as dietary supplement
21 October 2013,
01:15:21
Publication date: 25 January
2014
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 88
Author(s): A. Karioti , E. Giocaliere , C. Guccione , G. Pieraccini , E. Gallo , A. Vannacci , A.R. Bilia
The efficiency of 1D and 2D NMR spectroscopy along with HPLC-DAD–MS analyses in characterising the content of a dietary supplement is demonstrated. Experiments directly performed on a lyophilised sample of a commercial product gave details on the quality control of the product. The lack of the marker constituents of some of the declared plant species (Crataegus oxyacantha, Olea europea, Capsella bursa-pastoris and Fumaria officinalis) and the presence of banned adulterants, responsible for the strong antihypertensive effect of the supplement were established. The analyses proved the presence of indole alkaloids belonging to the group of Rauwolfia sp., such as ajmaline, reserpine and yohimbine. Quantitative HPLC analysis showed that the content of reserpine in the product was in the therapeutic range and therefore responsible for the collapses of the patients.
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 88
Author(s): A. Karioti , E. Giocaliere , C. Guccione , G. Pieraccini , E. Gallo , A. Vannacci , A.R. Bilia
The efficiency of 1D and 2D NMR spectroscopy along with HPLC-DAD–MS analyses in characterising the content of a dietary supplement is demonstrated. Experiments directly performed on a lyophilised sample of a commercial product gave details on the quality control of the product. The lack of the marker constituents of some of the declared plant species (Crataegus oxyacantha, Olea europea, Capsella bursa-pastoris and Fumaria officinalis) and the presence of banned adulterants, responsible for the strong antihypertensive effect of the supplement were established. The analyses proved the presence of indole alkaloids belonging to the group of Rauwolfia sp., such as ajmaline, reserpine and yohimbine. Quantitative HPLC analysis showed that the content of reserpine in the product was in the therapeutic range and therefore responsible for the collapses of the patients.
Graphical abstract
Determination of pKa values of a triptolide derivative and its impurities by pressure-assisted capillary electrophoresis
21 October 2013,
01:15:21
Publication date: 25 January
2014
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 88
Author(s): Jian-Ling Wang , Xue-Jiao Xu , Dong-Ying Chen
A pressure-assisted capillary zone electrophoresis method was developed to determine the pK a values of a triptolide derivative (LLDT-246) and its impurities. The method was performed in an uncoated fused-silica capillary under the electric voltage of 18kV and 50mbar of external pressure applied simultaneously. A series of running electrolyte buffers were used with pH ranging between 2.2 and 10.0 with the constant ionic strength of 0.05M. The values of pK a of LLDT-246 and two impurities were calculated based on the pH dependence of effective mobilities (μ eff). The pK a value of LLDT-246 was in good agreement with that of determined by potentiometric titration method.
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 88
Author(s): Jian-Ling Wang , Xue-Jiao Xu , Dong-Ying Chen
A pressure-assisted capillary zone electrophoresis method was developed to determine the pK a values of a triptolide derivative (LLDT-246) and its impurities. The method was performed in an uncoated fused-silica capillary under the electric voltage of 18kV and 50mbar of external pressure applied simultaneously. A series of running electrolyte buffers were used with pH ranging between 2.2 and 10.0 with the constant ionic strength of 0.05M. The values of pK a of LLDT-246 and two impurities were calculated based on the pH dependence of effective mobilities (μ eff). The pK a value of LLDT-246 was in good agreement with that of determined by potentiometric titration method.
Improved detection of variants in recombinant human interferon alpha-2a products by reverse-phase high-performance liquid chromatography on a core–shell stationary phase
21 October 2013,
01:15:21
Publication date: 25 January
2014
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 88
Author(s): Yonghong Li , Chunming Rao , Lei Tao , Junzhi Wang , Barry Lorbetskie , Michel Girard
The detection of variants is one of the important aspects in quality control of recombinant DNA drugs. In this study, a gradient reverse-phase high-performance liquid chromatography (RP-HPLC) method with fluorescence detection is described for the separation of interferon alpha-2a (rhIFN α-2a) from several product related variants. The methodology employed a core–shell C18 column with a linear gradient elution of 0.2% (v/v) trifluoroacetic acid (TFA)-acetonitrile (ACN) at 1.0mL/min, and the temperature of the column was maintained at 60°C. The method was validated in terms of linearity, sensitivity, intra- and inter-day variations. Compared to the European Pharmacopeia RP-HPLC method of rhIFN α-2a analysis, this new method can separate N-methionylated variant in both drug substance and finished product, and analyze the variants in untreated, oxidized sample and slightly degraded samples more efficiently. In conclusion the method has an improved capability to detect variants in rhIFN α-2a products.
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 88
Author(s): Yonghong Li , Chunming Rao , Lei Tao , Junzhi Wang , Barry Lorbetskie , Michel Girard
The detection of variants is one of the important aspects in quality control of recombinant DNA drugs. In this study, a gradient reverse-phase high-performance liquid chromatography (RP-HPLC) method with fluorescence detection is described for the separation of interferon alpha-2a (rhIFN α-2a) from several product related variants. The methodology employed a core–shell C18 column with a linear gradient elution of 0.2% (v/v) trifluoroacetic acid (TFA)-acetonitrile (ACN) at 1.0mL/min, and the temperature of the column was maintained at 60°C. The method was validated in terms of linearity, sensitivity, intra- and inter-day variations. Compared to the European Pharmacopeia RP-HPLC method of rhIFN α-2a analysis, this new method can separate N-methionylated variant in both drug substance and finished product, and analyze the variants in untreated, oxidized sample and slightly degraded samples more efficiently. In conclusion the method has an improved capability to detect variants in rhIFN α-2a products.
Graphical abstract
A novel sample preparation and on-line HPLC–DAD–MS/MS–BCD analysis for rapid screening and characterization of specific enzyme inhibitors in herbal extracts: Case study of α-glucosidase
21 October 2013,
01:15:21
Publication date: 25 January
2014
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 88
Author(s): D.Q. Li , J. Zhao , J. Xie , S.P. Li
Drug discovery from complex mixture like Chinese herbs is a challenge and extensive false positives make the obtainment of specific bioactive compounds difficult. In the present study, a novel sample preparation method was proposed to rapidly reveal the specific bioactive compounds from complex mixtures using α-glucosidase as a case. Firstly, aqueous and methanol extracts of 500 traditional Chinese medicines were carried out with the aim of finding new sources of α-glucosidase inhibitors. As a result, the extracts of fruit of Terminalia chebula (FTC), flowers of Rosa rugosa (FRR) and Eugenia caryophyllata (FEC) as well as husk of Punica granatum (HPG) showed high inhibition on α-glucosidase. On-line liquid chromatography–diode array detection–tandem mass spectrometry and biochemical detection (HPLC–DAD–MS/MS–BCD) was performed to rapidly screen and characterize α-glucosidase inhibitors in these four extracts. After tentative identification, most of compounds with inhibitory activity in the investigated crude extracts were found to be tannins commonly recognized as non-specific enzyme inhibitors in vitro. Subsequently, the four extracts were treated with gelatin to improve specificity of the on-line system. Finally, two compounds with specific α-glucosidase inhibition were identified as corilagin and ellagic acid. The developed method could discover specific α-glucosidase inhibitors in complex mixtures such as plant extracts, which could also be used for discovery of specific inhibitors of other enzymes.
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 88
Author(s): D.Q. Li , J. Zhao , J. Xie , S.P. Li
Drug discovery from complex mixture like Chinese herbs is a challenge and extensive false positives make the obtainment of specific bioactive compounds difficult. In the present study, a novel sample preparation method was proposed to rapidly reveal the specific bioactive compounds from complex mixtures using α-glucosidase as a case. Firstly, aqueous and methanol extracts of 500 traditional Chinese medicines were carried out with the aim of finding new sources of α-glucosidase inhibitors. As a result, the extracts of fruit of Terminalia chebula (FTC), flowers of Rosa rugosa (FRR) and Eugenia caryophyllata (FEC) as well as husk of Punica granatum (HPG) showed high inhibition on α-glucosidase. On-line liquid chromatography–diode array detection–tandem mass spectrometry and biochemical detection (HPLC–DAD–MS/MS–BCD) was performed to rapidly screen and characterize α-glucosidase inhibitors in these four extracts. After tentative identification, most of compounds with inhibitory activity in the investigated crude extracts were found to be tannins commonly recognized as non-specific enzyme inhibitors in vitro. Subsequently, the four extracts were treated with gelatin to improve specificity of the on-line system. Finally, two compounds with specific α-glucosidase inhibition were identified as corilagin and ellagic acid. The developed method could discover specific α-glucosidase inhibitors in complex mixtures such as plant extracts, which could also be used for discovery of specific inhibitors of other enzymes.
Graphical abstract
Screening for multiple weight loss and related drugs in dietary supplement materials by flow injection tandem mass spectrometry and their confirmation by liquid chromatography tandem mass spectrometry
21 October 2013,
01:15:21
Publication date: 25 January
2014
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 88
Author(s): Fenhong Song , Douglas Monroe , Aref El-Demerdash , Cynthia Palmer
A new method has been developed using flow injection tandem mass spectrometry to semi-quantitatively screen for weight loss drugs, including sibutramine, N-desmethylsibutramine, N-didesmethylsibutramine, and phenolphthalein in dietary supplements. Positive identification of these drugs in samples was further confirmed and quantified by liquid chromatography tandem mass spectrometry. The degradation products of sibutramine were observed and identified by LC–MS/MS which include N-desmethylsibutramine, N-didesmethylsibutramine, N-formyldesmethylsibutramine, and N-formyldidesmethylsibutramine.
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 88
Author(s): Fenhong Song , Douglas Monroe , Aref El-Demerdash , Cynthia Palmer
A new method has been developed using flow injection tandem mass spectrometry to semi-quantitatively screen for weight loss drugs, including sibutramine, N-desmethylsibutramine, N-didesmethylsibutramine, and phenolphthalein in dietary supplements. Positive identification of these drugs in samples was further confirmed and quantified by liquid chromatography tandem mass spectrometry. The degradation products of sibutramine were observed and identified by LC–MS/MS which include N-desmethylsibutramine, N-didesmethylsibutramine, N-formyldesmethylsibutramine, and N-formyldidesmethylsibutramine.
Graphical abstract
Phase quantification of antihypertensive drugs – Chlorthalidone, Hydrochlorothiazide, Losartan and combinations, Losartan/Chlorthalidone and Losartan/Hydrochlorothiazide – by the Rietveld method
21 October 2013,
01:15:21
Publication date: 25 January
2014
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 88
Author(s): Weberton Reis do Carmo , Fabio Furlan Ferreira , Renata Diniz
The identification and quantification of crystalline phases of antihypertensive drugs – Losartan potassium (LOS-K), Hydrochlorothiazide (HCTZ) and Chlorthalidone (CTD) were carried out by means of X-ray powder diffraction data and the Rietveld method. Quantitative phase analyses of Losartan potassium/Chlorthalidone (LOS-K/CTD) and Losartan potassium/Hydrochlorothiazide (LOS-K/HCTZ) combinations were also evaluated. The results indicated that for diuretics (HCTZ and CTD) only one crystalline phase was found in samples, and for LOS-K the crystal structure showed similarity between the Bragg peaks to the phase described as monoclinic and space group P21/c. After one year storage, the orthorhombic one was also observed in this sample.
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 88
Author(s): Weberton Reis do Carmo , Fabio Furlan Ferreira , Renata Diniz
The identification and quantification of crystalline phases of antihypertensive drugs – Losartan potassium (LOS-K), Hydrochlorothiazide (HCTZ) and Chlorthalidone (CTD) were carried out by means of X-ray powder diffraction data and the Rietveld method. Quantitative phase analyses of Losartan potassium/Chlorthalidone (LOS-K/CTD) and Losartan potassium/Hydrochlorothiazide (LOS-K/HCTZ) combinations were also evaluated. The results indicated that for diuretics (HCTZ and CTD) only one crystalline phase was found in samples, and for LOS-K the crystal structure showed similarity between the Bragg peaks to the phase described as monoclinic and space group P21/c. After one year storage, the orthorhombic one was also observed in this sample.
Graphical abstract
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