PREPARATION, PURIFICATION, AND STABILITY OF TUBERCULIN.

The method used to produce "Connaught" tuberculin purified protein derivative (PPD) is described. The tuberculin PPD for the multiple-puncture method was shown to be stable for at least 24 months at 5 C; tuberculin PPD for the intracutaneous method was shown to be stable at 5 C and 24 C for a period of 18 months in the presence of Tween 80. Evans blue or brillant vital red was added to tuberculin PPD for improved testing by the multiple-puncture method. These tinted tuberculin preparations were found to be as stable as the Connaught tuberculin PPD preparations without dye at 5 C. Freeze-dried tuberculin PPD with Plasdone as an inert base was found to be remarkably stable for a period of at least 24 months at 5, 24, and 37 C.