Loop-Based Multiple Heart-Cutting Two-Dimensional Liquid Chromatography for Target Analysis in Complex Matrices

Loop-based multiple heart-cutting (MHC) two-dimensional liquid chromatography (2D-LC) is presented as a solution to quantify target,components in complex matrices, such as additives in polymers, at Very high chromatographic resolution. The determination of hexabromo-cyclododecane (HEED) in polystyrene,(PS) is described. One dimensional (D-1) LC analysis with UV detection did not allow quantitation of the main isomers of HBCD, due to peak overlap with polymer components. MHC 2D-LC analysis provided the separation power, accuracy, and repeatability needed for quantitative analysis of the additives of interest. Heart-cuts from peaks of the D-1-chromatogram or entire regions of interest are :sampled into loops, where they remain parked until their sequential-reinjection onto the second dimension (D-2) column. A column set consisting Of phenyl (D-1) and C-18 (D-2) stationary phases gave baseline separation in D-2 between HBCD and PS background. Linearity for spiked polymer samples was achieved over a range of 0.02-1.00 wt % HBCD relative to the amount of polymer. The limit of quantitation was estimated at 0.01 wt % HBCD in PS. A peak area SD of 0.7% obtained for ten replicates of a real sample demonstrated excellent repeatability of the analysis. MHC 2D-LC is an elegant solution for quantitative analyses of difficult-to-sepatate samples When conventional D-1 separation fails.