Length Of Spot Research Articles

Direct quantification of thin-layer chromatograms by empirical methods : Mathematical analysis

Ideally, the material in a spot on a two-dimensional chromatogram forms a bivariate normal distribution in which the base of the figure corresponds to the dimensions of the circular spot and the height of the curve is a function of the maximum absorbance. Using a paraboloid as an approximation of the Gaussian figure, it has been possible to construct a mathematical model of a series of chromatographic standards over a five hundred-fold range of values and to define mathematically deviant “spots” which were more compact or more diffuse than the standard series. The model has been used to evaluate the various empirical techniques of direct chromatographic analysis including: spot length, area, maximum absorbance, (area) (maximum absorbance), total absorbance and slit scanning with fixed and fixed-ratio slit length. It was found that slit scanning where the length of the slit is a constant fraction of the spot diameter is probably the best technique for mono-dimensional chromatograms while for two-dimensional chromatograms the product of (spot area) × (maximum absorbance) appears to be the best method.

Quantitative paper radiochromatography using tollens reagent—I: The application of 131I to radiometric estimation of monosaccharides and polyols

For the estimation of saccharides, a radiochromatographic quantitative method, based on the reaction with ammoniacal silver nitrate, has been developed. Conditions for the quantitative deposition of silver on the filter paper have been established. The silver deposit formed was transformed into Ag 131I. The radioactivity of 131I located in the spots is related to the amount of the substance determined. The method has been checked using six substances, representing aldoses, ketoses, hexitols and cyclitols. The relationships between integrated spot activity, maximal spot activity and radiometrically estimated spot length, and the amount of substance have been studied.

Experimental Study of Effect of Crystallite Size Statistics on X-Ray Diffractometer Intensities

The relative rms deviation σ of the intensity of a rapidly rotating polycrystallite specimen is σ=[6.5R sinθ]/[h(mNeff)½], where R=goniometer radius, θ=Bragg angle, h=(hf+hs)/2, hf=length of focal spot, hs=length of receiving slit, m=multiplicity factor, and Neff the effective number of irradiated crystallites. Experimental data on silicon powder specimens are presented to show the dependence of σ on crystallite sizes, choice of x-ray wavelengths and various other experimental parameters. Comparisons of data for rapidly rotating and stationary specimens having crystallite sizes in the 30–50 μ range show that rotation improves σ by a factor of 7 or 8 for peak intensities and 4 or 5 for integrated intensities, using a standard diffractometer.