World Congress on Biosensors 2014

World Congress on Biosensors 2014
Biosensors 2014

Thursday, 14 November 2013

Just Published: Journal of Pharmaceutical and Biomedical Analysis

A new issue of this journal has just been published. To see abstracts of the papers it contains (with links through to the full papers) click here:
Journal of Pharmaceutical and Biomedical Analysis
http://rss.sciencedirect.com/publication/science/5266

Selected papers from the latest issue:

Improving the efficiency of quantitative 1H NMR: An innovative external standard–internal reference approach

13 November 2013, 23:32:30
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.

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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

13 November 2013, 23:32:30
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.

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Determination of pKa values of a triptolide derivative and its impurities by pressure-assisted capillary electrophoresis

13 November 2013, 23:32:30
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.

Improved detection of variants in recombinant human interferon alpha-2a products by reverse-phase high-performance liquid chromatography on a core–shell stationary phase

13 November 2013, 23:32:30
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.

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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

13 November 2013, 23:32:30
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.

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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

13 November 2013, 23:32:30
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.

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Phase quantification of antihypertensive drugs – Chlorthalidone, Hydrochlorothiazide, Losartan and combinations, Losartan/Chlorthalidone and Losartan/Hydrochlorothiazide – by the Rietveld method

13 November 2013, 23:32:30
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.

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Comparison of (bio-)transformation methods for the generation of metabolite-like compound libraries of p38α MAP kinase inhibitors using high-resolution screening

13 November 2013, 23:32:30
Publication date: 25 January 2014
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 88
Author(s): David Falck , Fatie Rahimi Pirkolachachi , Martin Giera , Maarten Honing , Jeroen Kool , Wilfried M.A. Niessen
Four hydrophobic p38α mitogen-activated protein kinase inhibitors were refluxed with 7.5% hydrogen peroxide at 80°C and irradiated with visible light in order to generate more hydrophilic conversion products. The resulting mixtures were analyzed in a high-resolution screening (HRS) platform, featuring liquid chromatographic separation coupled in parallel with a fluorescence enhancement based continuous-flow affinity bioassay towards the p38α mitogen-activated protein kinase and with high-resolution (tandem) mass spectrometry on an ion-trap-time-of-flight hybrid instrument. The results were compared with similar data where chemical diversity was achieved by means of electrochemical conversion or incubation with either human liver microsomes or cytochrome P450s from Bacillus megaterium (BM3s). In total, more than 50 conversion products were identified. The metabolite-like compound libraries studied are discussed in terms of the reactions enabled, the retention of affinity, and the change in hydrophilicity by modification, in summary the ability to generate bioactive, more hydrophilic potential lead compounds. In this context, HRS is demonstrated to be an effective tool as it reduces the effort directed towards laborious synthesis and purification schemes.

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Quantitative determination of phenolic compounds by UHPLC-UV–MS and use of partial least-square discriminant analysis to differentiate chemo-types of Chamomile/Chrysanthemum flower heads

13 November 2013, 23:32:30
Publication date: 25 January 2014
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 88
Author(s): Bharathi Avula , Yan-Hong Wang , Mei Wang , Cristina Avonto , Jianping Zhao , Troy J. Smillie , Diego Rua , Ikhlas A. Khan
A new rapid UHPLC-UV-QTOF/MS method has been developed for the simultaneous analysis of nine phenolic compounds [(Z)-2-β-d-glucopyranosyloxy-4-methoxycinnamic acid (cis-GMCA), chlorogenic acid, (E)-2-β-d-glucopyranosyloxy-4-methoxycinnamic acid (trans-GMCA), quercetagetin-7-O-β-d-glucopyranoside, luteolin-7-O-β-d-glucoside, apigenin-7-O-β-d-glucoside, chamaemeloside, apigenin 7-O-(6″-O-acetyl-β-d-glucopyranoside), apigenin] and one polyacetylene (tonghaosu) from the flower heads of Chamomile/Chrysanthemum samples. The chromatographic separation was achieved using a reversed phase C18 column with a mobile phase of water and acetonitrile, both containing 0.05% formic acid. The ten compounds were completely separated within 15min at a flow rate of 0.25mL/min with a 2μL injection volume. The different chemo-types of Chamomiles/Chrysanthemum displayed variations in the presence of chemical constituents. German Chamomile samples confirmed the presence of cis-GMCA, trans-GMCA, apigenin-7-O-β-d-glucoside and tonghaosu as major constituents whereas Roman chamomile samples confirmed the presence of chamamaeloside and apigenin as major compounds. The Chrysanthemum morifolium samples showed the presence of luteolin-7-O-β-d-glucose as the major compound. The method was applied for the analysis of various commercial products including capsules, tea bags, body and hair care products. LC-mass spectrometry with electrospray ionization (ESI) interface method is described for the evaluation of ten compounds in plant samples and commercial products. This method involved the detection of [M+Na]+ and [M+H]+ ions in the positive mode. Partial least squares discriminant analysis (PLS-DA) was used to visualize commercial samples quality and may be of value for discriminating between chamomile types and Chrysanthemum with regards to the relative content of individual constituents. The results indicated that the method is suitable as a quality control test for various Chamomile/Chrysanthemum samples and market products.

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Batch-to-batch reproducibility of Transferon™

13 November 2013, 23:32:30
Publication date: 25 January 2014
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 88
Author(s): Emilio Medina-Rivero , Giovanna Merchand-Reyes , Lenin Pavón , Said Vázquez-Leyva , Gilberto Pérez-Sánchez , Nohemí Salinas-Jazmín , Sergio Estrada-Parra , Marco Velasco-Velázquez , Sonia Mayra Pérez-Tapia
Human dialyzable leukocyte extracts (DLEs) are heterogeneous mixtures of low-molecular-weight peptides that modulate immune responses in various diseases. Due their complexity, standardized methods to identify their physicochemical properties and determine that production batches are biologically active must be established. We aimed to develop and validate a size exclusion ultra performance chromatographic (SE-UPLC) method to characterize Transferon™, a DLE that is produced under good manufacturing practices (GMPs). We analyzed an internal human DLE standard and 10 representative batches of Transferon™, all of which had a chromatographic profile characterized by 8 main peaks and a molecular weight range between 17.0 and 0.2kDa. There was high homogeneity between batches with regard to retention times and area percentages, varying by less than 0.2% and 30%, respectively, and the control chart was within 3 standard deviations. To analyze the biological activity of the batches, we studied the ability of Transferon™ to stimulate IFN-γ production in vitro. Transferon™ consistently induced IFN-γ production in Jurkat cells, demonstrating that this method can be included as a quality control step in releasing Transferon™ batches. Because all analyzed batches complied with the quality attributes that were evaluated, we conclude that the DLE Transferon™ is produced with high homogeneity.

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