Method validation for determination of alkaloid content in goldenseal root powder

A fast, practical ambient extraction methodology followed by isocratic liquid chromatography (LC) analysis with UV detection was validated for the determination of berberine, hydrastine, and canadine in goldenseal (Hydrastis canadensis L.) root powder. The method was also validated for palmatine, a major alkaloid present in the possible bioadulterants Coptis, Oregon grape root, and barberry bark. Alkaloid standard solutions were linear over the evaluated concentration ranges. The analytical method was linear for alkaloid extraction using 0.3-2 g goldenseal root powder/100 mL extraction solvent. Precision of the method was demonstrated using 10 replicate extractions of 0.5 g goldenseal root powder, with percent relative standard deviation for all 4 alkaloids < or = 1.6. Alkaloid recovery was determined by spiking each alkaloid into triplicate aliquots of neat goldenseal root powder. Recoveries ranged from 92.3% for palmatine to 101.9% for hydrastine. Ruggedness of the method was evaluated by performing multiple analyses of goldenseal root powder from 3 suppliers over a 2-year period. The method was also used to analyze Coptis root, Oregon grape root, barberry bark, and celandine herb, which are possible goldenseal bioadulterants. The resulting chromatographic profiles of the bioadulterants were significantly different from that of goldenseal. The method was directly transferred to LC with mass spectrometry, which was used to confirm the presence of goldenseal alkaloids tetrahydroberberastine, berberastine, canadaline, berberine, hydrastine, and canadine, as well as alkaloids from the bioadulterants, including palmatine, jatrorrhizine, and coptisine.     

PVC ion-selective electrodes based on calcium bis-[dialkyl- and di-(4-alkylphenyl) phosphates] and mixed solvent mediators

PVC calcium ion-selective electrodes based on either calcium bis-di(n-decyl)phosphate or calcium bis-di[4-(1,1,3,3-tetramethylbutyl)phenyl]phosphate with various solvent mediators (alone or in pairs) have been evaluated with particular respect to interference from Na(+), K(+), Mg(2+), Sr(2+), Ba(2+), Mn(2+), Cu(2+), Ni(2+) and Zn(2+) ions. PVC calcium ion-selective electrodes based on calcium bis-di[4-(n-octyl)phenyl]phosphate with varied amounts of decan-l-ol plus di-n-octyl phenylphosphonate showed a continuous gradation in selectivity coefficients on going from a high fraction of decan-l-ol to a high fraction of the second mediator. Thus, k(pot)(Ca,Mg) changed from 1.6 for an electrode based exclusively on decan-l-ol to 4.9 x 10(-4) for one based completely on di-n-octyl phenylphosphonate. The corresponding k(pot)(Ca,Na) values were 7.0 x 10(-2) and 1.1 x 10(-3).     

Zur quantitativen Bestimmung von Aluminium, Eisen, Chrom, Zink, Kobalt, Nickel und Zinn

Ohne Zusammenfassung     

New techniques for the analysis of fine-scaled clustering phenomena within atom probe tomography (APT) data.

Nanoscale atomic clusters in atom probe tomographic data are not universally defined but instead are characterized by the clustering algorithm used and the parameter values controlling the algorithmic process. A new core-linkage clustering algorithm is developed, combining fundamental elements of the conventional maximum separation method with density-based analyses. A key improvement to the algorithm is the independence of algorithmic parameters inherently unified in previous techniques, enabling a more accurate analysis to be applied across a wider range of material systems. Further, an objective procedure for the selection of parameters based on approximating the data with a model of complete spatial randomness is developed and applied. The use of higher nearest neighbor distributions is highlighted to give insight into the nature of the clustering phenomena present in a system and to generalize the clustering algorithms used to analyze it. Maximum separation, density-based scanning, and the core linkage algorithm, developed within this study, were separately applied to the investigation of fine solute clustering of solute atoms in an Al-1.9Zn-1.7Mg (at.%) at two distinct states of early phase decomposition and the results of these analyses were evaluated.     

Circular Symmetry of Pinwheel Diffraction

A method is given for explicitly determining the autocorrelation of the pinwheel tiling by use of the substitution system generating the tiling. Using this a new proof of the circular symmetry of the diffraction of the pinwheel tiling is given. Communicated by Jean Bellissard Submitted: 8/10/2004 Accepted: 21/11/2005     

A Characterization of Model Multi-colour Sets

Model sets are always Meyer sets, but not vice versa. This article is about characterizing model sets (general and regular) amongst the Meyer sets in terms of two associated dynamical systems. These two dynamical systems describe two very different topologies on point sets, one local and one global. In model sets these two are strongly interconnected and this connection is essentially definitive. The paper is set in the context of multi-colour sets, that is to say, point sets in which points come in a finite number of colours, that are loosely coupled together by finite local complexity. Communicated by Jean Bellissard submitted 8/10/04, accepted 15/02/05     

The first three anisotropy constants of nickel

The technique of ferromagnetic resonance at 23 GHz has been used to determine the first three anisotropy constants of pure Ni down to 4.2K. A temperature and orientation dependent linewidth has also been observed.     

Auditory thresholds and kanamycin-induced hearing loss in the guinea pig assessed by a positive reinforcement procedure

Absolute thresholds from 125 Hz to 52 kHz are determined for six guinea pigs trained by a positive reinforcement method. Four to five hundred trials were conducted during daily testing sessions and little between- or within-subject variability was found. Two of the six animals were subsequently treated with kanamycin and the development of a hearing loss for the high frequencies was followed. Loss of outer and to a lesser extent inner hair cells was well correlated with the threshold shift observed. Contrary to the experience of previous investigators, this operant training procedure has proved as efficient as that for other species of experimental animals, such as the monkey and the chinchilla. It holds excellent promise for future auditory behavioral work with the guinea pig.