A Colorimetric Reaction Between Gold Chloride and Toxins Apparently Indicative of Toxic Strength

Summary By means of a colorimetric reaction obtained by adding gold chloride to toxic-broth filtrates we have been able to obtain toxin values which in most instances closely approximate the toxin values obtained by animal tests. Thus far we have not observed a colorimetric end-point which parallels the combining value (toxin-toxoid) of toxins. We have no data as to the mechanism of the reaction. Whether the reaction is due to a specific toxin-gold chloride combination, or whether some other factor or factors are involved remains to be proven. Whatever the mechanism of the reaction may be, the results strongly suggest that a practical, gold chloride colorimetric method of standardizing toxic-values of broth filtrates may be developed.