Molecular Columns Research Articles

Molecular weight determination of random coil polypeptides from collagen by molecular sieve chromatography

The chromatographic properties on molecular sieve columns of polypeptides from collagen were investigated under conditions in which the polypeptides are random coils. An acrylamide gel (Bio-Gel P-150) was found suitable for the separation and molecular weight determination of polypeptides with molecular weights of 1,500 to 24,000. An 8% agarose gel (Bio-Gel A-1.5) could be used for the molecular weight range 3,000 to 200,000 and gave as good resolution as the acrylamide gel for peptides chromatographing within the inclusion volume of both gels.

N-Glucosyl Metabolite of Pyrazon in Red Beets

Red beets (Beta vulgaris L., var. Detroit Dark Red) converted the herbicide 5-amino 4-chloro-2-phenyl-3(2H)-pyridazinone (pyrazon) to N-2-chloro-4-phenyl-3-(2H)-pyridazinone glucosamine. Isolation was accomplished by water, benzene, and alcohol extraction of foliage followed by purification through molecular sieve columns. Identification was established by infrared spectroscopy, and thin layer and gas liquid chromatography.

Thermal expansion of β-succinic acid and α-adipic acid in relation to their crystal structures

The thermal expansion quadrics of β -succinic acid and α -adipic acid have been determined by X-ray Weissenberg method. In adipic acid, X-ray measurements have been made between —100 and +100°C and in succinic acid between —150 and +130°C. In these monoclinic crystals, the minimum expansion corresponds to the c axis, which coincides with the direction of the hydrogen-bonded molecular columns. In other directions along which van der Waals forces prevail, thermal expansion is greater, being maximum perpendicular to the (100) planes, the direction of the obtuse bisectrix of the molecular packing angle. The thermal expansion is quantitatively explained by assuming an increase in the angular vibration of the molecules.

Application of solid-gas chromatography to the enrichment of low-level tritium samples

A gas chromatographic technique which permits the quantitative separation of traces of tritium from samples up to 200 ml NTP of hydrogen using relatively small molecular sieve columns is described. The technique applies a combination of elution and displacement chromatography and takes advantage of the variation of the retention time with temperature. The implications of the technique to low-level tritium assay are discussed.

Gas chromatography applied to the study of the liquid products of the low-temperature fluidized-bed carbonization of coal

Acidic and neutral fractions of a light oil distillate and tar distillates produced by the low-temperature fluidized-bed carbonization of a New South Wales bituminous coal were examined by gas chromatography using silicone, Apiezon L and Molecular sieve 5A columns up to 220°. The separation of the phenols was incomplete, but eleven peaks were tentatively identified. The distribution of phenols in the light oil distillate and in the tar distillate was very similar, the major components being the cresols and certain xylenols. The neutral fractions were highly aliphatic as shown by infrared spectra of the whole oils and of components collected after chromatographic separation. Successive removal of olefins, aromatics and normal paraffins from the light oil followed by chromatography of the residue in each case showed that normal paraffins and 1-olefins ranging from C 7 to C 15 (mainly C 9 to C 13) were the major constituents. The tar distillate appeared to be similarly constituted except that the proportion of olefins was somewhat less. The range was C7 to C21 approximately (mainly C11 to C20). Isoparaffins, isomeric olefins and perhaps naphthenes were also present in minor amounts in both cases. Very little aromatic material appeared to be present.

Three-dimensional refinement of the structure of β-succinic acid

The crystal structure of β-succinic acid has been refined by three-dimensional Fourier methods, followed by differential refinements with series-termination corrections and anisotropic temperature factors. The central C—C bond at 1·533 Å is shown not to differ significantly from the length of the single bond in diamond, but the next bond connecting the chain to the carboxyl group, C—COOH, is 1·485 ± 0·013 Å and the contraction here is highly significant. The C—O distances are 1·252 and 1·322 Å, with standard deviations of about 0·012 Å. The main feature of the thermal motion is that the movement in the direction of the hydrogen-bonded molecular columns is very much less than in any other direction in the crystal, and also much less than in pure molecular crystals like benzene or naphthalene. In other directions where van der Waals contacts only exist the movement is greater. There is a molecular angular oscillation of perhaps 9° r.m.s. amplitude about an axis close to the axis of the molecular columns. A difference synthesis in the plane of the oxygen atoms is given which shows the hydrogen atom responsible for hydrogen bonding.