Identification and control of metal-chelating chromatographic artifacts in the analysis of a malonohydrazide derivative drug compound

Two unusual chromatographic artifact peaks were detected in the HPLC analysis for content of a malonohydrazide derivative drug and drug-related impurities. The artifacts were identified as the copper(II) chelating complexes with the drug compound and one of the process impurities. Our investigations suggested that built-up of Cu(2+) contamination in the HPLC system was the primary source for formation of the chelating artifacts. A rinse procedure using diluted EDTA solution was developed, and demonstrated to effectively purge trace level of heavy metals including Cu(2+) from the system, and therefore inhibited the formation of both chelates. Furthermore, the rinse was shown to introduce no detrimental impact on the response accuracy of the active drug compound and related impurities.