ELECTROMETRIC pH DETERMINATIONS OF DIFFERENT AGAR MEDIA AT 25 AND 45 C

Abstract

In all tests performed using antibiotic test medium No. 1, APHA standard reference, BBL standard methods, violet red bile, and desoxycholate lactose agars, the overall mean values of pH readings were significantly higher (p<0.01) when determined at 25 C than at 45 C. This difference varied between 0.14 and 0.38 pH unit. Whether this difference has practical significance in routine laboratory use of these media was not determined.