Analysis of Hexabromocyclododecane Diastereomers and Tetrabromobisphenol-A Using a Novel Method Combining Supercritical Fluid Chromatography with Tandem Mass Spectrometry

Oral Presentation

Prepared by D. Stevens1, L. Mullin1, K. Rosnack1, J. Burgess1, B. van Bavel2, I. Ericson Jogsten2, A. Aubin1
1 - Waters Corporation, 34 Maple Street, Milford, MA, 01757, United States
2 - Orebro University, MTM Research Centre, Orebro, , Sweden


Contact Information: doug_stevens@waters.com; 508-482-4672


ABSTRACT

The brominated flame retardants hexabromocyclododecane (HBCDD) and tetrabromobisphenol-A (TBBPA) are compounds which are monitored for their presence in the human population and in the environment. The ability to resolve the various HBCDD isomers from one another is important due to the differences in isomeric distribution in biota, abiotic systems and technical formulations. Separation of the three α-, β- and γ - diastereomers of HBCDD and TBBPA can be achieved using reversed-phase liquid chromatography (RP-LC) and this is currently the method of choice. Supercritical fluid chromatography (SFC) has demonstrated higher chromatographic efficiency in many applications commonly performed using RP-LC due to higher diffusivity and lower viscosity of the supercritical fluid and is particularly well suited to isomeric separations. The use of SFC for this analysis offers the advantage of lower solvent consumption, as well as the ability to inject from sample aliquots contained in a variety of solvents not compatible with RP-LC analysis.

We describe here a method using supercritical CO2 and methanol to baseline resolve the three most abundant HBCDD diastereomers and TBBPA in a three minute run time. Multiple reaction monitoring (MRM) acquisition mode was used on a tandem quadrupole mass spectrometer operated in negative ion electrospray. Ionization was enhanced by the addition of a make-up flow, which was introduced to the post-column effluent. Method limit of detection (LOD) and limit of quantification (LOQ) for α-, β-, and γ - HBCDD were based on peak-to-peak signal to noise ratios of greater than 3 or 10, respectively. The LOD for all HBCDD diastereomers was 100 fg/ul, and LOQs 500 fg/ul for α- and γ - HBCDD and 250 fg/ul for β- HBCDD. In order to test the efficacy of this method, a subset of human serum and whale blubber extracts were analyzed, and the detection of a sub-pg/ul concentration of α- HBCDD was made.