Electrophoresis of acidic glycosaminoglycans in hydrochloric acid: a micro method for sulfate determination

A rapid and simple method for estimation of the sulfate content of less than 1 μg of acidic glycosaminoglycans is presented. The procedure is based on the fact that the electrophoretic mobility in 0.1 M hydrochloric acid is proportional to the sulfate content of the polysaccharide.     

A new colorimetric method for the determination of 6-aminopenicillanic acid.

A new, sensitive colorimetric method for the estimation of 6-aminopenicillanic acid is described. The procedure is based upon formation of a 2,4-pentanedione derivative of 6-aminopenicillanic acid followed by a second reaction with p-dimethylaminobenzaldehyde (Ehrlich's reagent), resulting in a red product which absorbs at 538 nm. The absorbance response is linear from 0 to 350 μg of 6-aminopenicillanic acid. Penicillins do not interfere with the assay, but 6-aminopenicilloic acid does.     

A colorimetric micro method for the determination of formyl groups

The characteristic purple colour formed by N-formyl-N'-2,4-dinitrophenyl-hydrazine in the presence of piperidine and acetone was made the basis of a new quantitative method for the determination of formyl groups. Samples containing N-formyl groups (up to 0.4mumole) are hydrazinolysed at 97-98 degrees for 1hr. and are dinitrophenylated after the removal of excess of hydrazine. Interference from 2,4-dinitrophenylhydrazine is eliminated by subjecting the dinitrophenylated samples to chromatography on an alumina column. Interference arising from the formation of N-acetyl-N'-2,4-dinitrophenylhydrazine, when determining formyl groups in samples containing acetyl, can be avoided by a paper-chromatographic separation before analysis. A standard procedure is described. The method gives satisfactory results when applied to N-formyl-amino acids. Gramicidin, when analysed by this method, was found to contain 0.89 mole of formyl group/mole for a molecular weight of 1880. The method indicated the absence of formyl groups from lysozyme, a protein known not to contain such groups. Generally, the analytical values obtained by the method are within 100+/-4% of theory.