Development of normal phase-high performance liquid chromatography-atmospherical pressure chemical ionization-mass spectrometry method for the study of 6,6′-bis-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-benzo[1,2,4]-triazin-3-yl)-[2,2′]-bipyridine hydrolytic degradation

• Published in: Journal of Chromatography A 2011-09, Vol.1218 (37), p.6369-6378
• Main Authors: Nicolas, Grégory, Jankowski, Christopher K., Lucas-Lamouroux, Christine, Bresson, Carole
• Format: Article
• Language: English
• Subjects: Actinides; Analytical chemistry; APCI-MS coupling; Chemistry; Chromatographic methods and physical methods associated with chromatography; Chromatography; CyMe 4BTBP; Degradation; Degradation products; dioxane; dissociation; ethanol; Ethyl alcohol; Exact sciences and technology; hexane; Hydrolysis; isopropyl alcohol; Liquid-liquid extraction; methanol; methylene chloride; nitric acid; Normal phase chromatography; nuclear fuels; octanol; Other chromatographic methods; radioactive waste; Separation; Spectroscopy; tandem mass spectrometry; waste management
• ISSN: 0021-9673
• DOI: 10.1016/j.chroma.2011.07.003

In the field of nuclear waste management, the 6,6′-bis-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-benzo[1,2,4]-triazin-3-yl)-[2,2′]-bipyridine (CyMe 4BTBP) is a polycyclic N-based molecule eligible to remove actinides from spent nuclear fuel by liquid–liquid extraction processes. In such processes, the organic phase containing the extracting molecules will undergo hydrolysis and radiolysis, involving degradation products. The purpose of this work was to develop a normal phase chromatography (NP-HPLC) coupled to atmospherical pressure chemical ionisation-mass spectrometry (APCI-MS) method to separate and identify degradation products of CyMe 4BTBP dissolved in octanol, submitted to HNO 3 hydrolysis. 1 mol L −1 HNO 3 hydrolysis conditions were used regarding the selective actinides extraction (SANEX) process, while 3 mol L −1 HNO 3 conditions were applied for the group actinide extraction (GANEX) process. The first step consisted in optimizing the chromatographic separation conditions using a diode array detection (DAD). Retention behavior of a non hydrolyzed mixture of N,N′-dimethyl-N,N′-dioctyl-hexyloxyethyl-malonamide (DMDOHEMA), a malonamide used in the SANEX process to increase the kinetic of extraction, and CyMe 4BTBP were investigated on diol-, cyano-, and amino-bonded stationary phases using different mobile phase compositions. These latter were hexane with different polar modifiers, i.e. dioxane, isopropanol, ethanol and methylene chloride/methanol. The different retention processes in NP-HPLC were highlighted when using various stationary and mobile phases. The second step was the setting-up of the NP-HPLC-APCI-MS coupling and the use of the low-energy collision dissociation tandem mass spectrometry (CID-MS/MS) of the precursor protonated molecules that allowed the separation and the characterization of the main hydrolytic CyMe 4BTBP degradation product under a 3 mol L −1 HNO 3 concentration. Investigation of the CID-MS/MS fragmentation pattern was used to suggest the potential ways leading to this hydrolysis degradation product. This NP-HPLC-APCI-MS method development is described for the first time for the CyMe 4BTBP and should provide separation methods regarding the analysis of polycyclic N-based extracting molecules and more generally for the investigation of the organic phase coming from liquid–liquid extraction processes used in nuclear fuel reprocessing.