The Determination of Histamine in Bacterial Cultures

Abstract

The histamine in bacterial cultures can be extracted quantitatively by a mixture of 3 parts of chloroform and 1 part of amyl alcohol. The extracting apparatus consists of 2 bulbs connected by a vertical U tube; after partly filling the apparatus with the solvent, the culture (made strongly alkaline) is added to one bulb and a 0.5% soln. of H2SO4 to the other. The apparatus is set in a rack and tilted for 24 hours; this transfers the histamine to the acid soln. The acid extract is made slightly alkaline and boiled to remove ammonia, volatile amines, and amyl alcohol. The histamine is detd. colorimetrically after being coupled with diazotized sulfanilic acid. Histidine and other imidazol acids are not extracted. Imidazol, methyl imidazol, and imidazol ethyl alcohol are extracted if present, but these bases are not precipitated by phosphotungstic acid from dilute solns.; histamine is completely removed. Histamine di-picrate can be readily prepd. from the acid extracts and identified by its melting point and mixed melting point.