A Method for the Assay of Penicillin in Animal Feeds

Publisher Website
Google Scholar
Abstract
A penicillin pad plate assay technic has been developed for the assay of animal feeds at levels as low as 0.5 g./ton of feed. Feeds which do not contain an antibiotic do not give blank values. The penicillin is ex- tracted from the feed with 99% methanol-1% water and dilutions of the extract in 95% methanol are pipetted on filter paper pads which are allowed to dry before being placed on an agar plate which has been seeded with Staphylococcus aureus 209-P. Standards are prepared either by extracting a standard feed of the same composition to which a known amt. of penicillin has been added or by adding penicillin to an extract of the antibiotic-free feed. The use of aqueous methanol as an extracting and diluting agent for penicillin in feeds presents no difficulties through destructior of the penicillin. The extreme sensitivity of the assay is achieved by the use of an extremely thin layer of agar and the inclusion of 0.15% sulfasuxidine in the medium.
Keywords

This publication has 0 references indexed in Scilit: