Enantiomeric specific determination of hexabromocyclododecane by liquid chromatography-quadrupole linear ion trap mass spectrometry in sediment samples

This paper describes the determination and quantitation of hexabromocyclododecane (HBCD) enantiomers by liquid chromatography-quadrupole linear ion trap mass spectrometry (LC-QqLIT-MS). The method is based on the use of a chiral chromatographic column Nucleodex beta-PM (200 mm x 4.0 mm, 5 microm), which allows a good separation between HBCD enantiomers [(+/-)alpha, (+/-)beta and (+/-)gamma] in less than 15 min and the detection is performed by a Q-Trap instrument. Linearity was checked between 0.05 and 25 injected ng. Limits of detection (LODs) were in the range of 0.3-1.5 pg, limits of quantification (LOQs) were between 1 and 6 pg, and both values are lower than those published in the literature applying LC-MS-MS methods. The method was applied to sediment samples collected along the Cinca River, a tributary of the Ebro River (northeast of Spain). Samples were extracted and purified following a pressurized liquid extraction method. LODs of the method were between 0.12 and 5.61 ng/g and LOQs, from 0.38 to 1.87 ng/g. Total HBCD levels in these sediments ranged from not detected to 2660 ng/g dry weight. Enantiomeric fractions (EFs) were calculated and compared with EF obtained from standard injections. It is important to note that calculated EFs were corrected using (2)H(18)-labeled HBCD standards, in order to compensate matrix effect. EFs obtained in sediment samples suggested a higher presence of (+)alpha-HBCD and (+)gamma-HBCD in technical mixture, this suggests that it is not a racemic mixture.