A comprehensive evaluation of two sample treatment procedures for the determination of emerging and historical halogenated flame retardants in biota

Imma Tolosa,Sylvia Sander,Sarah Choyke,Yann Aminot,David Huertas

doi:10.1007/s11356-020-10966-y

Imma Tolosa, Sylvia Sander + Show 3 more

Open Access

https://doi.org/10.1007/s11356-020-10966-y

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Abstract

Two different sample preparation protocols for the determination of 37 emerging and historical halogenated flame retardants (HFRs) in marine tissues were compared with regards to extraction recovery, lipid removal efficiency, repeatability, reproducibility, and ability to measure sub-ng g−1 (dry weight) concentrations in marine biota. One method involved a purification step using gel permeation chromatography (GPC) followed by a HPLC fractionation step on a Partisil amino-cyano normal phase (GPC-Partisil procedure) and the other more traditional method was based on sulphuric acid treatment followed by silica column fractionation (H2SO4-silica procedure). The samples were analysed by gas chromatography (GC) and liquid chromatography (LC) tandem mass spectrometry (MS/MS). Sample fractionation in both methods enabled unique sample preparation procedures to isolate the GC from the LC amenable compounds. Both methods could remove > 99% of the lipids which was necessary prior to GC- and LC-MS/MS analyses. The majority of the target compounds (70%) had acceptable recoveries between 60–120% for both methods. However, the sulphuric acid treatment resulted in the degradation of the TBP-AE and the silica column fractionation resulted in the loss of BEH-TEBP and the elution of PBB-Acr and TBBPA-BME in the unsuitable fraction. High recoveries of DBE-DBCH (α+β), EHTBB, BTBPE, BEH-TEBP, and PBB-Acr were attributed to matrix effects, suggesting the need to use isotope-labelled surrogate standards of the target compounds. The optimisation of the silica column chromatography, GPC, and Partisil fractionation is described and discussed to afford easy implementation of the method. The method using GPC followed by Partisil fractionation is more efficient and more reproducible than the sulphuric acid-silica procedure. The application of this method to marine biota reference materials revealed the presence of relatively high concentrations of DBE-DBCH isomers and BDE-47 in fish samples. The method detection limits comply with the recommendations of the European Commission.

Highlights

Responsible Editor: Ester HeathElectronic supplementary material The online version of this article contains supplementary material, which is available to authorized users.The marine environment and its biological resources are threatened by the presence of anthropogenic chemicals originating from industrial, domestic, and agricultural applications
Sulphuric acid treatment is one of the clean-up procedures frequently used to remove lipid content in biota tissue samples when analysing for legacy persistent organic pollutants (POPs) and Halogenated flame retardants (HFRs) contaminants (Covaci et al 2007)
Most of the recoveries of the gas chromatography (GC) amenable HFRs treated directly with concentrated sulphuric acid fell between 60 and 120% with relative standard deviation (RSD) < 20% (Fig. S1) These results are in accordance with the EU guidance document for pesticide residues analysis in food, where the acceptable mean recoveries are in the range of 70–120% and the associated repeatability of relative standard deviation RSD < 20% (European Commission 2017)

Summary

Introduction

Biota samples are among the relevant candidate matrices proposed by environmental agencies, such as the Water Frame Directive (WFD) and Marine Strategy Frame Directive (MSFD) of the European Union; the Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR Convention); and the Baltic Marine Environment Protection Commission (Helsinki Commission, HELCOM) In this framework, the European Commission recommended monitoring for trace levels of BFRs in seafood (European Commission, 2014), and emerging HFRs were included in the Norman network list of emerging contaminants (Network of reference laboratories, research centres, and related organisations for monitoring emerging environmental substances, NORMAN 2016). Current purification methods rely on phase separation of sulphuric acid (H2SO4)–treated extracts or molecular size fractionation by gel permeation chromatography (GPC), while fractionation methods rely on normal phase column chromatography These techniques can be combined to achieve greater lipid removal from the extracts prior to analysis. Due to the wide range of physicochemical properties of the HFRs, the transferability of methods between compounds with previously validated levels of PCBs and PBDEs is rather limited as a priori knowledge of the elution behaviour or stability to sulphuric acid treatment is not guaranteed

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