[Express method of determining phenylacetic acid in the culture broth during the biosynthesis of benzylpenicillin]. / Ekspress-metod opredeleniia feniluksusnoi kisloty v kul'tural'noi zhidkosti pri biosinteze benzilpenitsillina.

Phenylacetate acid (PAA) is transferred by extraction from the fermentation broth filtrate into toluol. The extract is applied to a Silufol plate with an aluminium foil lining (silica gel sorbent, Czechoslovakia). Reference solutions of PAA are also applied to the same plate. The reference and test solutions are applied dropwise (spots of 5--6 x 10(-3)m in diameter). For PAA development the spots are sprayed with a freshly prepared saturated solution of potassium manganate in 6N H2SO4. PAA of the test samples is developed as a dull ring against grey background and that of the reference solution is developed as a circle. The amount of PAA in the spot is determined by using correlation between the spot area and the amount of PAA applied. One plate of 225 X 10(-4) m2 can be used for about 300 analyses. One analysis takes 300--600 seconds.