Suspect Screening of Liquid Crystal Monomers (LCMs) in Sediment Using an Established Database Covering 1173 LCMs

Recent studies have suggested that
liquid crystal monomers (LCMs)
are emerging contaminants in the environment, and knowledge of this
class of substances is very rare. Here, we reviewed existing LCM-related
documents, i.e., publications and patents, and established a database
involving 1173 LCMs. These 1173 LCMs were further calculated for their
physicochemical properties, i.e., persistence (P), bioaccumulation
(B), long-range transport potential (LRTP), and Arctic contamination
and bioaccumulation potential (ACBAP). We found that 476 out of them
were P&B chemicals (99% of them were halogenated), and 320 of
them could have ACBAP properties (67% of them were halogenated). This
LCM database was further applied for suspect screening of LCMs in n = 33 sediment samples by use of gas chromatography coupled
to quadrupole time-of-flight mass spectrometry (GC-QTOF/MS). We tentatively
identified 26 LCM formulas, which could have 43 chemical structures.
Two out of these 43 suspect LCM candidates, 1-butoxy-2,3-difluoro-4-(4-propylcyclohexyl)
benzene (3cH4OdFP) and 1-ethoxy-2,3-difluoro-4-(4-pentyl cyclohexyl)
benzene (5cH2OdFP), were fully confirmed by a comparison of unique
GC and MS characteristics with their authentic standards. Overall,
our present study expanded the previous LCM database from 362 to 1173,
and 1173 LCMs in this database were calculated for their physicochemical
properties. Meanwhile, taking n = 33 sediment samples
as an exercise, we successfully developed a suspect screening strategy
tailored for LCMs, and this strategy could have promising potential
to be extended to other environmental matrices.