Discrimination and quantitation of halobenzoic acid positional isomers upon Th(IV) coordination by mass spectrometry.

A fast and reliable mass spectrometry-based method has been developed to discriminate the positional isomers of o -, m - and p -C 6 H 4 XCO 2 H (X = F, Cl and Br). This is based on the distinct fragmentation patterns of isomeric ThCl 4 (C 6 H 4 XCO 2 ) - ions generated by electrospray ionization of the solutions with C 6 H 4 XCO 2 H isomers and ThCl 4 . Moreover, the composition of these positional isomers can be conveniently quantified without any pre-treatment according to the proportion of gas-phase fragmentation products.