title: Determination of cross-linking residues in a pharmaceutical polymer by liquid chromatography-high resolution full scan mass spectrometry.
abstract: A liquid chromatography-mass spectrometry (LC-MS) method was developed as limit test for an amine cross-linking residue in a pharmaceutical polymer. The method was based on full scan data with extracted ions for the accurate masses of dicyclohexylmethane-4, 4'-diamine (DMDA) and the internal standard 1,12-diaminododecane (DADD) obtained by Fourier transform MS. Dicyclohexylmethane-4,4-diisocyanate (DMDI) the reactive form of the cross-linking residue was determined as it decomposition product DMDA. Calibration curves for quantification of DMDA were linear in the range 2-100 ng/ml, the LOD was 1 ng/ml or 10 pg on column. Precisions/recoveries for spiked samples at the level of the limit of 1 ppm for DMDA and DMDI were +/-9.6%/38.6% and +/-14.5/10.0% (n=3), respectively. Unpredictable recovery was found in the extraction of polymer samples because of the complexity of the matrix and the reactivity of dicyclohexylmethane-4,4-diisocyanate (DMDI). PEG residues extracted from the polymer were found to cause ionization suppression and also affected the chromatography, these effects were reduced by using a gradient program. By using this method the level of amine residues in samples from different batches of polymers were determined to be much lower than the limit of 1 ppm. The method allowed comparison of the results obtained from the polymer before and after purification indicating that the residual DMDA could be decreased by a washing procedure.
authors.affiliation: Strathclyde Institute for Pharmacy and Biomedical Science, 27 Taylor Street, Glasgow G4 0NR, UK.
authors.forename: T
authors.initials: T
authors.lastname: Zhang
authors.forename: D G
authors.initials: DG
authors.lastname: Watson
authors.forename: Duo
authors.initials: D
authors.lastname: Lu
authors.forename: D
authors.initials: D
authors.lastname: Carr
authors.forename: L
authors.initials: L
authors.lastname: Trager
mesh_terms: D002853:Chromatography, Liquid; D003432:Cross-Linking Reagents / Q000032:analysis*; D003959:Diamines / Q000032:analysis; D004364:Pharmaceutical Preparations / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D053719:Tandem Mass Spectrometry / Q000379:methods* / Q000592:standards
chemical_list: D003432:Cross-Linking Reagents; D003959:Diamines; D004364:Pharmaceutical Preparations; D011108:Polymers