Analysis of hydroxylated polybrominated diphenyl ether metabolites by liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometry

Abstract

Hydroxylated polybrominated diphenyl ether (OH-PBDEs) metabolites have the potential to cause endocrine disruption as well as other health effects. Currently, gas chromatography/mass spectrometry (GC/MS) after derivatization is used for the analysis of OH-PBDEs. However, there is a need for the direct analysis of OH-PBDEs at relatively low concentrations in environmental and biological samples. Liquid chromatography with atmospheric pressure chemical ionization tandem mass spectrometry (LC/APCI-MS/MS) was evaluated for the analysis of nine OH-PBDEs, ranging from tri- to hexabrominated. Separation of the nine isomeric metabolites was achieved with reversed-phase liquid chromatography, followed by detection by APCI-MS in negative mode. Notably, a significant decrease in ionization was observed in 6-hydroxyl-substituted PBDE metabolites in the presence of an ortho-substituted bromine, relative to the other hydroxylated metabolites. This is probably due to the formation of dioxins in the source as a result of the high-temperature conditions, which prevented ionization by hydrogen abstraction. The MS/MS experiments also provided evidence of the neutral losses of HBr and Br(2), indicating the possible use of neutral loss scanning and selected reaction monitoring (SRM) for the screening of brominated metabolites in samples. The applicability of LC/APCI-MS/MS was demonstrated for the analysis of metabolites of BDEs 47 and 99 formed in human liver microsomes. The LC/APCI-MS/MS method was able to detect metabolites that had previously been identified by GC/MS following derivatization.

Sample preparation method for the speciation of polybrominated diphenyl ethers and their methoxylated and hydroxylated analogues in diverse environmental matrices

“…Subsequently, product ion scan mode was used to choose product ions and optimize collision energy. The typical fragment ions of analytes were consistent with the results in other papers [29,33,34]. The formation of specific fragment ions allowed the efficient analytical method based on the MRM mode.…”

“…Lupton et al [33] proposed an LC-MS/MS method and the separation of nine OH-PBDEs achieved in 35 min. In another paper [34], eight OH-PBDEs can be separated by using a ternary mixture of 5 mM ammonium acetate, acetonitrile and methanol as the mobile phases.…”

“…In the published work, only 2-4 OHtetraBDE isomer were analyzed and the separating degree was not satisfied [29,33,34]. While using the improved methods in this work, six most frequently detected OH-tetraBDE isomer, including two ortho-hydroxylated PBDEs (6-OH-BDE47 and 2 -OH-BDE68), two para-hydroxylated PBDEs (4 -OH-BDE49 and 4-OH-BDE42), two meta-hydroxylated PBDEs (3-OH-BDE47 and 5-OH-BDE47) [36], can be simultaneously identified, which were shown in Fig.…”

“…OH-PBDEs can be determined by GC/MS as their MeOanalogues via a methylated derivatization using diazomethane [10,25,26,32], but the toxicity and easy explosive of diazomethane make the analysis difficult to handle. Therefore, atmospheric pressure chemical ionization (APCI)-LC/MS/MS [29,33] and ionspray ionization (ISP)-LC/MS/MS [34] methods have been developed for the analysis of OH-PBDEs without the time consuming step of derivatization. However, the selectivity and sensitivity of LC-MS/MS methods need to be further improved to make it more efficient in OH-PBDEs analysis.…”

Recent Methodologies for Brominated Flame Retardant Determinations by Means of Liquid Chromatography–Mass Spectrometry

“…For example, the nonpolar nature of the diphenyl ether structure in PBDEs and the introduction of polar hydroxyl functional groups upon its metabolization provide a new molecule with different properties, such as nonvolatile nature that does not allow the direct analysis of PBDEs metabolites by GC-MS. Recent papers are focused on the development of LC-MS approaches for this purpose [9].…”