Investigation of Galaxolide degradation products generated under oxidative and irradiation processes by liquid chromatography/hybrid quadrupole time-of-flight mass spectrometry and comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry.

RATIONALE

Polycyclic musks have become a concern due to their bioaccumulation potential and ecotoxicological effects. The HHCB transformation product (TP) (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethyl-cyclopenta[γ]-2-benzopyran; HHCB-lactone) is the most stable intermediate generated and it is frequently detected in river waters. The aim of this work was the identification of relevant TPs generated from UV irradiation and ozone treatments.

METHODS

Identification of HHCB TPs was carried out by liquid chromatography/hybrid quadrupole time-of-flight mass spectrometry (LC/ESI-QTOF-MS) and two-dimensional gas chromatography/electron impact time-of-flight mass spectrometry (GC×GC-EI-TOF-MS). With LC/ESI-QTOF-MS, TPs were characterized by means of mass accuracy in both full-scan and MS/MS modes through information-dependent acquisition (IDA) and direct injection on-column. With stir bar sorptive extraction (SBSE)-GC×GC-EI-TOF-MS, identification was based on the enhanced separation capacity and screening of unknowns through the acquisition of full-range mass spectra.

RESULTS

The effectiveness of these complementary techniques allowed a detailed evaluation of the main TPs. Eighteen TPs were elucidated based on mass accuracy, in both full-scan and MS/MS modes using LC/ESI-QTOF-MS with mass errors below 5 ppm and 10 ppm (mostly), respectively. Most of the TPs had not been analytically identified in previous studies. Separation of the enantiomeric species (R) and (S) of HHCB-lactone, and the identification of other relevant TPs, was performed using SBSE-GC×GC-EI-TOF-MS.

CONCLUSIONS

LC/ESI-QTOF-MS and GC×GC-EI-TOF-MS analysis provides the best alternative for TP identification of chemicals of concern, which have a wide range of polarities and isobaric compounds. A prediction of PBT (persistence, bioaccumulation and toxicity) using the PBT Profiler program suggested a classification of 'very persistent' and 'very toxic' for most of the TPs identified.