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 0·4μmole) are hydrazinolysed at 97–98° 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.
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Research Article| February 01 1969
A colorimetric micro method for the determination of formyl groups
S. Usha Lakshmi ;
Biochem J (1969) 111 (4): 401–406.
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S. Usha Lakshmi, L. K. Ramachandran; A colorimetric micro method for the determination of formyl groups. Biochem J 1 February 1969; 111 (4): 401–406. doi: https://doi.org/10.1042/bj1110401
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