“Under the HCl solution and heating condition, penicillin antibiotics such as … (AMO), ampicillin (AMP), sodium cloxacillin (CLO), sodium carbenicillin (CAR) and sodium benzylpenicillin (BEN) could … with Fe(III) to produce Fe(II) which further reacted with Fe(CN)(6)(…-) to form a Fe(3)[Fe(CN)(6)](2) complex.”