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.
D000085:Acetates; D000096:Acetone; D000596:Amino Acids / Q000032:analysis; D002845:Chromatography; D002854:Chromatography, Paper; D003124:Colorimetry; D005561:Formates / Q000032:analysis*; D008722:Methods; D009113:Muramidase / Q000032:analysis*; D010659:Phenylhydrazines; D010880:Piperidines; D014449:Tyrothricin / Q000032:analysis*
D000085:Acetates; D000596:Amino Acids; D005561:Formates; D010659:Phenylhydrazines; D010880:Piperidines; D000096:Acetone; D014449:Tyrothricin; D009113:Muramidase