World Congress on Biosensors 2014

World Congress on Biosensors 2014
Biosensors 2014

Monday, 28 May 2012

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:

Application of the near-infrared spectroscopy in the pharmaceutical technology

28 May 2012, 09:52:59
Publication year: 2012
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 66
Marzena Jamrógiewicz
Near-infrared (NIR) spectroscopy is currently the fastest-growing and the most versatile analytical method not only in the pharmaceutical sciences but also in the industry. This review focuses on recent NIR applications in the pharmaceutical technology. This article covers monitoring, by NIR, of many manufacturing processes, such as granulation, mixing or drying, in order to determine the end-point of these processes. In this paper, apart from basic theoretical information concerning the NIR spectra, there are included determinations of the quality and quantity of pharmaceutical compounds. Some examples of measurements and control of physicochemical parameters of the final medicinal products, such as hardness, porosity, thickness size, compression strength, disintegration time and potential counterfeit are included. Biotechnology and plant drug analysis using NIR is also described. Moreover, some disadvantages of this method are stressed and future perspectives are anticipated.

Highlights

► This work presents NIR spectroscopy application in the pharmaceutical manufacturing. ► The physical point of view on NIR is shown also with the spectra interpretation. ► A collection of multi-thematic data, also contains aspects of bio-manufacturing. ► NIR quality controlling system of pharmaceuticals and biopharmaceuticals is verified. ► Implementation of NIR method on the contrary to scientific knowledge is pointed out.

HPTLC methods to assay active ingredients in pharmaceutical formulations: A review of the method development and validation steps

28 May 2012, 09:52:59
Publication year: 2012
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 66
D.H. Shewiyo, E. Kaale, P.G. Risha, B. Dejaegher, J. Smeyers-Verbeke, Y. Vander Heyden
High-performance thin-layer chromatography (HPTLC) is still increasingly finding its way in pharmaceutical analysis in some parts of the world. With the advancements in the stationary phases and the introduction of densitometers as detection equipment, the technique achieves for given applications a precision and trueness comparable to high-performance liquid chromatography (HPLC). In this review, the literature is surveyed for developed and validated HPTLC methods to assay active ingredients in pharmaceutical formulations published in the period 2005–2011. Procedures and approaches for method development, validation and quantitative assays are compared with the standard ways of conducting them. Applications of HPTLC in some other areas are also briefly highlighted.

The development and application of a system for simultaneously determining anti-infectives and nasal decongestants using on-line solid-phase extraction and liquid chromatography–tandem mass spectrometry

28 May 2012, 09:52:59
Publication year: 2012
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 66
Ghazanfar Ali Khan, Richard Lindberg, Roman Grabic, Jerker Fick
A method for the simultaneous analysis of antibiotics, antiviral and nasal decongestants in treated sewage effluent and surface water has been developed and validated. The method uses on-line solid phase extraction (SPE) of injected high-volume samples in conjunction with liquid chromatography–tandem mass spectrometry (LC–MS/MS). This method includes a range of antibiotics (Trimethoprim, Oxytetracycline, Ofloxacin, Norfloxacin, Ciprofloxacin, Azithromycin, Doxycycline, Sulfamethoxazole, Erythromycin and Clarithromycin), an antiviral (Oseltamivir) and nasal decongestants (Naphazoline, Oxymetazoline and Xylometazoline). The method's detection limits (MDLs) ranged from (0.2ngL−1) to (3.1ngL−1), based on a 1mL extraction volume. Its intra-day precision was determined by performing nine runs with 200ngL−1 samples; the intra-day relative standard deviation (RSD) ranged from 1% to 19%. Inter-day precision was determined by analyzing samples in triplicate over the course of three days, yielding relative standard deviations ranging from <5% to <26%. The linearity (R 2) for all compounds tested was >0.90. Spike relative recoveries ranged from 40% to 157% and 40% to 152% for STP effluent and surface water samples, respectively. Finally, the method was used to analyze real effluent and surface water.

HPTLC method for the simultaneous determination of four indole alkaloids in Rauwolfia tetraphylla: A study of organic/green solvent and continuous/pulse sonication

28 May 2012, 09:52:59
Publication year: 2012
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 66
Shikha Gupta, Karuna Shanker, Santosh K. Srivastava
A new validated high-performance thin-layer chromatographic (HPTLC) method has been developed for the simultaneous quantitation of four antipsychotic indole alkaloids (IAs), reserpiline (RP, 1), α-yohimbine (YH, 2), isoreserpiline (IRP, 3) and 10-methoxy tetrahydroalstonine (MTHA, 4) as markers in the leaves of Rauwolfia tetraphylla. Extraction efficiency of the targeted IAs from the leaf matrix with organic and ecofriendly (green) solvents using percolation, ultrasonication and microwave techniques were studied. Non-ionic surfactants, viz. Triton X-100, Triton X-114 and Genapol X-80 were used for extraction and no back-extraction or liquid chromatographic steps were used to remove the targeted IAs from the surfactant-rich extractant phase. The optimized cloud point extraction was found a potentially useful methodology for the preconcentration of the targeted IAs. The separation was achieved on silica gel 60F254 HPTLC plates using hexane-ethylacetate-methanol (5:4:1, v/v/v) as mobile phase. The quantitation of IAs (1–4) was carried out using the densitometric reflection/absorption mode at 520nm after post chromatographic derivatization using Dragendorff's reagent. The method was validated for peak purity, precision, accuracy, robustness, limit of detection (LOD) and quantitation (LOQ). Method specificity was confirmed using retention factor (R f ) and visible spectral (post chromatographic scan) correlation of marker compounds in the samples and standard tracks.

Highlights

► Development of a rapid HPTLC analytical method for the quality assessment of R. tetraphylla using ecofriendly (green) solvents. ► Extraction efficiency of the targeted indole alkaloids from the leaf matrix with organic and ecofriendly (green) solvents have been discussed. ► Non-ionic surfactants, Triton X-100, Triton X-114 and Genapol X-80 used as ecofriendly solvents for the extraction of targeted indole alkaloids. ► No back-extraction or liquid chromatographic steps were used to remove the targeted indole alkaloids from the surfactant-rich extractant phase. ► The optimized cloud point extraction was found a potentially useful methodology for the preconcentration of the targeted indole alkaloids.

Structural characterization of a novel degradant of the antifungal agent posaconazole

28 May 2012, 09:52:59
Publication year: 2012
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 66
Wendy Zhong, Xi Yang, Weidong Tong, Gary E. Martin
A number of degradants of the antifungal agent posaconazole have been isolated and characterized. Degradation chemistry occurs primarily in the piperazine moiety located near the center of the molecule and typically involves oxidative processes. At least one ring contraction product has also been fully characterized by MS and NMR methods. We report the isolation and characterization of a novel degradant of posaconazole in which remnants of the piperazine ring have been incorporated into a 1,4-benzodiazepine moiety. The structure of the novel degradant was unequivocally established through accurate mass measurements, MS/MS studies, H/D exchange, and a range of 2D NMR experiments that included 1,1-ADEQUATE and covariance calculated HSQC-1,1-ADEQUATE spectra.

Triprotic site-specific acid–base equilibria and related properties of fluoroquinolone antibacterials

28 May 2012, 09:52:59
Publication year: 2012
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 66
Aura Rusu, Gergő Tóth, Levente Szőcs, József Kökösi, Márta Kraszni, Árpád Gyéresi, Béla Noszál
The complete macro- and microequilibrium analyses of six fluoroquinolone drugs – ciprofloxacin, enrofloxacin, norfloxacin, pefloxacin, ofloxacin and moxifloxacin – are presented. Previous controversial literature data are straightened up, the protonation centers are unambiguously identified, and the protonation macro- and microconstant values are reported. The macroconstants were determined by 1H NMR-pH titrations while the microconstants were determined by a multi-modal spectroscopic-deductive methodology, in which methyl ester derivatives were synthesized and their NMR-pH titration data contributed to the evaluation of all the microconstants. The full 1H, 13C and 15N NMR assignments, NMR-pH profiles, macro- and microprotonation schemes and species-specific diagrams are included. Our studies show that the fluoroquinolones have three protonation centers: the carboxylate group, the N-1′ and N-4′ piperazine nitrogens and concentration of the uncharged microspecies is way below the values published earlier. The results could be well interpreted in terms of structural properties. The protonation macro- and microconstant values allow the pre-planned method development in techniques such as capillary zone electrophoresis and also, the interpretation of fluoroquinolone mechanism of biological action, including the pharmacokinetic properties, and antibacterial activities that are all heavily influenced by the states of protonation.

Highlights

► The protonation centers of fluoroquinolone antibacterials are unambiguously identified. ► The protonation macro- and microconstants of fluoroquinolones were determined. ► The results could be well explained in terms of their structural properties. ► Protonation states of these drugs are crucial for binding of bacterial DNA gyrase.

Usefulness of reversed-phase HPLC enriched with room temperature imidazolium based ionic liquids for lipophilicity determination of the newly synthesized analgesic active urea derivatives

28 May 2012, 09:52:59
Publication year: 2012
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 66
Jolanta Flieger, Anna Czajkowska-Żelazko, Marzena Rządkowska, Elżbieta Szacoń, Dariusz Matosiuk
Lipophilicity of several novel analgesic active 1-(1-arylimidazolidyn-2-ylidyn)-3-arylalkyl urea derivatives has been estimated by the use of chromatographic method. The investigated compounds were analyzed by reversed-phase high performance liquid chromatography (RP-HPLC) using mixtures of methanol or acetonitrile and water with addition of imidazolium based room temperature ionic liquids varying in an anion chaotropicity as the mobile phases. The relationships between log k values vs. concentration of organic solvent was used for determination of the log k w values by extrapolation technique. The partition coefficients (log P) values were calculated by means of the Pallas 3.1.1.2. and Spartan 10.0 softwares and further correlated with log k w measured experimentally in classical organic–aqueous eluent system and systems modified with ionic liquids addition. It was found that log k w values measured in eluent system modified with butyl-methyl imidazoilum chloride correlate the best with the logarithm of partition coefficient calculated by Pallas software (log P calc.). Furthermore, it was found that the examined compounds form H-bonding with imidazoilum cation of modifiers improving the chromatographic peak parameters (the symmetry factor, the theoretical plates number) especially when ionic liquid's anion was more chaotropic. Amphiphilic ionic liquid possessing longer alkyl chain substituent (OMIM BF4) can be considered as a new cationic surfactant. Micellar conditions improved separation selectivity of chloro- and methoxy substituted derivatives.

Quantification of main bioactive metabolites from saffron (Crocus sativus) stigmas by a micellar electrokinetic chromatographic (MEKC) method

28 May 2012, 09:52:59
Publication year: 2012
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 66
Sándor Gonda, Péter Parizsa, Gyula Surányi, Gyöngyi Gyémánt, Gábor Vasas
Saffron is an expensive spice, cultivated in many regions of the world. Its chief metabolites include crocins, which are responsible for the coloring ability, safranal, which is the main essential oil constituent, and picrocrocin which is the main bitter constituent of the spice. A simple micellar capillary electrochromatographic (MEKC) method capable of quantifying all three types of main constituents was established. The pH, sodium dodecyl sulphate (SDS) content and electrolyte concentration of the background electrolyte was optimized. A simple extraction protocol was developed which can extract all metabolites of different polarity from the saffron stigmas. Optimal background electrolyte composed of 20mM disodium phosphate, 5mM sodium tetraborate, 100mM SDS, pH was set 9.5. Optimal extracting solvent was the background electrolyte, incubated with the sample for 60min. The proposed method allows quantification of picrocrocin, safranal, crocetin- Di-(β-d-gentiobiosyl) ester and crocetin (β-d-glycosyl)-(β-d-gentiobiosyl) ester within 17.5min, with limit of detection values ranging from 0.006 to 0.04mg/ml, from a single stigma.

A high pH based reversed-phase high performance liquid chromatographic method for the analysis of aminoglycoside plazomicin and its impurities

28 May 2012, 09:52:59
Publication year: 2012
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 66
Li Tan, Kenneth B. Wlasichuk, Donald E. Schmidt, Robert L. Campbell, Pam Hirtzer, Lisa Cheng, Dane E. Karr
A reversed-phase high performance liquid chromatographic (RP-HPLC) method has been developed for the aminoglycoside (AG) plazomicin (ACHN-490). This method employed a high pH mobile phase (pH>11) with a gradient of 0.25M ammonium hydroxide in water and acetonitrile, an XBridge C18 column and UV detection at 210nm. Although the molar UV absorption of plazomicin is weak, the high pH conditions of this method allow for higher loadings, which compensates for the inherent low UV sensitivity. Under these high pH conditions, impurities and degradants were base line separated from plazomicin. The mobile phases used for this method allowed for on-line mass detection for the impurities and degradants. The RP-HPLC method has been validated in terms of specificity, linearity and range, accuracy, and precision. The analytical method met specificity requirements of a homogenous peak with no interferences from the blank or from the known impurities in plazomicin. The linearity of the method for the plazomicin impurity determination was excellent, with a coefficient of determination (r 2) of 0.9993, over the freebase (FB) concentration range of 0.0025–3.0mg/mL. The method is capable of detecting impurities down to 0.1% of the peak area of plazomicin. A single point standard at a concentration of 1.0mg/mL FB was validated over the range of 50–150% for quantitation of the freebase content (the assay) in bulk drug substance. The mean recoveries of FB are in the range 98.6–102.0% with a mean RSD (relative standard deviation) <1.0%. The study also examined the method precision for purity, impurities and the assay with two instruments on two different days. The method showed adequate accuracy and precision for the intended use. This high pH method was successfully used to determine the impurity and measure the drug content in the final plazomicin drug substance. In addition, the method with an on-line mass spectrometry detector has been used to characterize the structures of the impurities in plazomicin.

Non-destructive detection of adulterated tablets of glibenclamide using NIR and solid-phase fluorescence spectroscopy and chemometric methods

28 May 2012, 09:52:59
Publication year: 2012
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 66
Rafael da Silva Fernandes, Fernanda Saadna Lopes da Costa, Patrícia Valderrama, Paulo Henrique Março, Kássio Michell Gomes de Lima
This study describes a method for non-destructive detection of adulterated glibenclamide tablets. This method uses near infrared spectroscopy (NIRS) and fluorescence spectroscopy along with chemometric tools such as Soft Independent Modeling of Class Analogy (SIMCA), Partial Least Squares-Discriminant Analysis (PLS-DA) and Unfolded Partial Least Squares with Discriminant Analysis (UPLS-DA). Both brand name (Daonil) and generic glibenclamide tablets were used for analysis. The levels of glibenclamide in each type of tablet were evaluated by derivative spectrophotometry in the ultraviolet region. The results obtained from the NIR and fluorescence spectroscopy along with those obtained from multivariate data classification show that this combined technique is an effective way to detect adulteration in drugs for the treatment of diabetes. In the future, this method may be extended to detect different types of counterfeit medications.

Comparison of solid phase microextraction versus spectroscopic techniques for binding studies of carbamazepine

28 May 2012, 09:52:59
Publication year: 2012
Source:Journal of Pharmaceutical and Biomedical Analysis, Volume 66
Barbara Bojko, Dajana Vuckovic, Janusz Pawliszyn
The binding of carbamazepine to human serum albumin was studied in vitro using solid-phase microextraction (SPME) with liquid chromatography–ultraviolet detection (LC–UV), as well as spectroscopic fluorescence and nuclear magnetic resonance (1H NMR) techniques. We were able to recognize one high affinity binding site with both fluorescence and SPME methods. Additionally, SPME experiment showed the existence of one lower affinity binding site for carbamazepine at the range of concentrations studied with fluorescence. The analysis of Hill's plot indicated positive cooperativity between drugs located in these two binding sites. Two low affinity-binding sites have been found with SPME–LC–UV analysis performed in parallel to 1H NMR study, which does not show any complex formation. In conclusion, the results of the studies with carbamazepine as a model drug showed the advantages of simultaneous use of solid phase microextraction and spectroscopic methods in protein binding studies and indicated complementary information, which can be obtained with the use of SPME. Furthermore, we show that SPME in combination with liquid chromatography–mass spectrometry permitted direct in vitro determination of plasma–protein binding and direct in vivo evaluation of inter-animal variability in free concentrations of carbamazepine at physiologically relevant concentrations, the type of experiments typically inaccessible by spectroscopic techniques due to poor sensitivity and different mode of implementation. 

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