Studies on Muscle of Aquatic Animals-XIX

Determination of Glycine by Nitroanilic Acid

Abstract

We have designated the method determining the glycine in the muscle extractives by the nitroanilic acid following in T_OWN¹⁾ and M_ACRA and P_LIMMER²⁾. We have found in the first place that the glycine nitroanilate should be treated with over 90per cent of alcohol at below 5°C. to absolutely precipitate it (see Figure and Table 1). Although the ancient authors have used the barium chloride to free the glycine from the nitroanilate in the aqueous solution, the barium nitroanilate was found to be dissolved such quantity in water as the value of the glycine nitrogen was too much appreciated. We have, therefore, decomposed the nitroanilate by means of the active carbon through which the glycine was flowed out in the free form from the anilate.
It has been reported that the histidine, which is also precipitated with the nitroanilic acid³⁾, is difficult to remove entirely from the solution by the phosphotungstic acid⁴⁾, but it has been found recently⁵⁾ that the histidine picrate is absorbable in the active carbon in accompany with the picric acid. We have, therefore, adopted this method to isolate the histidine from the glycine solution.
The resulted method for determination of the glycine in the muscle extractives is shown in the last part of this paper.