Precipitation of phenyl and phenoxypenicillin from solutions using ammonium sulfate

An easy, rapid, and available method for separating 6-aminopenicillanic acid (6-APA), benzylpenicillin (penicillin G), and other related molecules from aqueous solutions or complex industrial broths is described. A high concentration of ammonium sulphate induces partially or totally the precipitation of the penicillin present in the solutions, while 6-APA, phenylacetic, and phenoxyacetic acid always remain in the supernatant. The filtration through No. 4 Pyrex glass-fiber filter or Whatman 3MM paper permits the separation of the compounds present in the supernatant from the other ones precipitated. The precipitated product was identified, in all cases, as ammonium penicillin. This method is described here for the first time.