Abstract
Comparison of Voges-Proskauer reaction between the colored solution with diacetyl-guanidino compounds system (O'Meara's method) and diacetyl-guanidino compounds-α-naphthol system (Eggleton's method) were studied by visible absorption spectra, using such guanidino compounds as creatine, 1, 1-dimethylguanidine and 1, 1-pentamethyleneguanidine.
O'Meara's method was performed in the concentrated alkaline solution or in the similar diluted alkaline solution as in Eggleton's method.
And following results were obtained;
(1) We found absorption maxima of the colored solution by O'Meara's method of three guanidino compounds to have 520, 515 and 515 mμ, respectively.
And the same peak of 405 mμ was commonly observed in the diluted alkaline solution by O'Meara's method with each guanidino compounds, besides the range of 500 mμ.
(2) Color intensities of the colored solutions at 405 mμ and 500 mμ region by O'Meara's method were dependent on the concentration of alkali.
(3) By Eggleton's method, however, color intensities were dependent on the concentration of α-naphthol.
(4) In comparison of the colored solutions with absorption spectra and reaction processes, it was indicated that the colored substances by Eggleton's and O'Meara's method might be different from each other.
(5) The limit of colorimetric determination of diacetyl by V-P reaction were as follows.
Eggleton's method with 1, 1-pentamethylenegua-nidine was 0.01 μmol/ml and O'Meara's method with creatine was 0.1 μmol/ml.
