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Chemometric Analysis (chemometric + analysis)
Selected AbstractsA near-infrared spectroscopic investigation of relative density and crushing strength in four-component compactsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 3 2009Steven M. Short Abstract Near-infrared spectroscopy (NIRS) is commonly employed for the analysis of chemical and physical attributes of intact pharmaceutical compacts. Specifically, NIRS has proven useful in the nondestructive measurement of tablet hardness or crushing strength. Near-infrared (NIR) reflectance and transmittance spectra were acquired for 174 13-mm compacts, which were produced according to a four-constituent mixture design (29 points) composed of anhydrous theophylline, lactose monohydrate, microcrystalline cellulose, and soluble starch. Six compacts were produced for each design point by compacting at multiple pressures. Physical testing and regression analyses were used to model the effect of variation in relative density (and crushing strength) on NIR spectra. Chemometric analyses demonstrated that the overall spectral variance was strongly influenced by anhydrous theophylline as a result of the experimental design and the component's spectroscopic signature. The calibration for crushing strength was more linear than the relative density model, although accuracy was poorer in comparison to the density model due to imprecision of the reference measurements. Based on the consideration of reflectance and transmittance measurements, a revised rationalization for NIR sensitivity to compact hardness is presented. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:1095,1109, 2009 [source] The analysis of pH-dependent protonated conformers of 1-hydroxyethylidene-1,1-diphosphonic acid by means of FT-Raman spectroscopy, multivariate curve resolution and DFT modellingJOURNAL OF RAMAN SPECTROSCOPY, Issue 12 2009Werner Barnard Abstract 1-Hydroxyethylidene-1,1-diphosphonic acid (HEDP) solutions in the pH range 0.98,13.00 were analysed using FT-Raman spectroscopy and 31P and 23Na NMR spectroscopy. Vibrational bands for different protonated species were observed in the Raman spectra, whereas only a single NMR signal that shifted with pH was observed for all samples over the entire pH range. No significant shift in the 23Na NMR signal was observed, confirming that formation of Na+(aq) complexes did not take place; hence, no interference with the different protonated forms of HEDP occurred. Vibrational bands were assigned using density functional theory(DFT)-calculated spectra of the most likely conformers in solution. Multivariate curve resolution was performed on the Raman spectra in the region containing the PO stretching vibrations to determine the number of protonated species formed over the entire pH range. Chemometric analysis compares very favourably with the experimental species distribution diagram which was generated using the reported log KH values. Copyright © 2009 John Wiley & Sons, Ltd. [source] Infraspecific chemical variability of the essential oil of Lavandula dentata L. from AlgeriaFLAVOUR AND FRAGRANCE JOURNAL, Issue 2 2006Leila Bousmaha Abstract Fifty-five samples of essential oil obtained from individual plants of Lavandula dentata L. var. dentata from Algeria were analysed using GC and 13C-NMR spectroscopy. The results were submitted to chemometric analysis (k-means clustering and principal component analysis). Two principal clusters of equal importance were distinguished within the essential oil of the individuals of L. dentata. The samples belonging to cluster I were characterized by a very high content of 1,8-cineole (mean value 48%). Conversely, the mean composition of the samples of cluster II were dominated by 1,8-cineole, , -pinene, trans -pinocarveol and linalool. Copyright © 2005 John Wiley & Sons, Ltd. [source] Direct analysis of clinical relevant single bacterial cells from cerebrospinal fluid during bacterial meningitis by means of micro-Raman spectroscopyJOURNAL OF BIOPHOTONICS, Issue 1-2 2009Michaela Harz Abstract Bacterial meningitis is a relevant public health concern. Despite the availability of modern treatment strategies it is still a life-threatening disease that causes significant morbidity and mortality. Therefore, an initial treatment approach plays an important role. For in-time identification of specific bacterial pathogens of the cerebrospinal fluid (CSF) and emerged antimicrobial and adjunctive treatment, microbiological examination is of major importance. This contribution spotlights the potential of micro-Raman spectroscopy as a biomedical assay for direct analysis of bacteria in cerebrospinal fluid of patients with bacterial meningitis. The influence of miscellaneous artificial environments on several bacterial species present during bacterial meningitis was studied by means of Raman spectroscopy. The application of chemometric data interpretation via hierarchical cluster analysis (HCA) allows for the differentiation of in vitro cultured bacterial cells and can also be achieved on a single cell level. Moreover as proof of principle the investigation of a CSF sample obtained from a patient with meningococcal meningitis showed that the cerebrospinal fluid matrix does not mask the Raman spectrum of a bacterial cell notably since via chemometric analysis with HCA an identification of N. meningitidis cells from patients with bacterial meningitis could be achieved. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Coumarins and phenolic fingerprints of oak and Brazilian woods extracted by sugarcane spiritJOURNAL OF SEPARATION SCIENCE, JSS, Issue 21 2009Alexandre Ataide da Silva Abstract A total of 25 sugarcane spirit extracts of six different Brazilian woods and oak, commonly used by cooperage industries for aging cachaça, were analyzed for the presence of 14 phenolic compounds (ellagic acid, gallic acid, vanillin, syringaldehyde, synapaldehyde, coniferaldehyde, vanillic acid, syringic acid, quercetin, trans -resveratrol, catechin, epicatechin, eugenol, and myricetin) and two coumarins (scopoletin and coumarin) by HPLC-DAD-fluorescence and HPLC-ESI-MSn. Furthermore, an HPLC-DAD chromatographic fingerprint was build-up using chemometric analysis based on the chromatographic elution profiles of the extracts monitored at 280,nm. Major components identified and quantified in Brazilian wood extracts were coumarin, ellagic acid, and catechin, whereas oak extracts shown a major contribution of catechin, vanillic acid, and syringaldehyde. The main difference observed among oak and Brazilian woods remains in the concentration of coumarin, catechin, syringaldehyde, and coniferaldehyde. The chemometric analysis of the quantitative profile of the 14 phenolic compounds and two coumarins in the wood extracts provides a differentiation between the Brazilian wood and oak extracts. The chromatographic fingerprint treated by multivariate analysis revealed significant differences among Brazilian woods themselves and oak, clearly defining six groups of wood extracts: (i) oak extracts, (ii) jatobá extracts, (iii) cabreúva-parda extracts, (iv) amendoim extracts, (v) canela-sassafrás extracts and (vi) pequi extracts. [source] Improved chromatographic fingerprints for facile differentiation of two Ganoderma spp.BIOMEDICAL CHROMATOGRAPHY, Issue 3 2009Chun-Mei Fu Abstract This paper addresses a comprehensive and comparative study of six phytochemical extraction methods for triterpenes from the fruiting body of Ganoderma spp. Quantitative analysis of extracts was performed by HPLC with photodiode array detection. In general, pressurized liquid extraction and microwave-assisted extraction under optimized conditions produce better yields, and the former also significantly reduces the total time of extraction and manipulation of a sample, as well as the amount of solvent used in comparison with conventional soxhlet, reflux, ultrasonic, and methanol,CO2 supercritical fluid extractions. Based on the improved extraction protocol, the fingerprinting profiles for two species of Lingzhi were established using the consistent chromatographic features of 12 authentic samples. Eleven common peaks of ganoderic/ganoderenic acids were identified using LC-ESI-MS-MS. These specific triterpene groups were adopted as chemical markers for Lingzhi. Using chemometric analysis, the developed fingerprinting was successfully applied to differentiate between the two species under the Ganoderma genus and is applicable as a method for quality evaluation of this valuable medicinal fungus and its related proprietary products. Copyright © 2008 John Wiley & Sons, Ltd. [source] Determination of the enantiomeric excess of an M3 antagonist drug substance by chemometric analysis of the IR spectra of different guest-host complexesCHIRALITY, Issue 5 2006Lili Zhou Abstract A novel approach for the potential on-line determination of the enantiomeric excess (ee) of an M3 antagonist drug substance combining attenuated total reflectance infrared (ATR-IR) spectroscopy, guest-host complexes, and chemometric data analysis is described. Chiral recognition through a formation of diastereomeric complexes was measured by ATR-IR. Small changes on the IR spectra reflect the interaction between the guest (M3) and host (chiral selector). These changes are measured as a function of M3 enantiomer excess. The standard error of prediction is 1.3 ee%. The prediction results based on the IR method were in good agreement with the gravimetric method. The robustness of the calibration model was evaluated by varying the concentration of the chiral selector, the pH of the solution, and the organic solvents. The stability of the calibration model was also demonstrated through measuring different sets of samples on different days. Chirality, 2006. © 2006 Wiley-Liss, Inc. [source] | ||||||||||