ASSESSMENT OF TRACE-ELEMENT CONTENT IN PENICILLIN-G BY INDUCTIVELY COUPLED PLASMA-ATOMIC EMISSION-SPECTROMETRY FOR REGULATORY PURPOSES

A specific and direct method for the determination of 11 trace elements (Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Ti and Zn) in penicillin G was worked out in an exploratory way using inductively coupled plasma-atomic emission spectrometry (ICP-AES) with a V-groove nebulizer for highly concentrated solutions. This particular sample introduction system was chosen to improve the expected insufficient detection limits of ICP-AES (low-mu-g . g-1 range). Perfectly matrix-matched, buffer stabilized, calibration standard solutions were prepared on the basis of high pure PeG (15% w/v). Trace elements were added as EDTA-chelates under buffered conditions and after sonication to prevent irreversible precipitation of penicillanic acid. The limits of detection for the trace elements investigated were found to be in the ng . g-1 range. Relative standard deviations were found to be lower than 3%, and recoveries within +/- 5% deviation.