Analysis of Dechlorane Plus and related norbornene-based flame retardants in foods by gas chromatography - high resolution mass spectrometry Jekaterina Rjabova 1,2 , Arturs Viksna 2 , Dzintars Zacs 1 1 Institute of Food Safety, Animal Health and Environment ‘‘BIOR’’, Lejupes iela 3, Riga, LV-1076, Latvia 2 University of Latvia, Jelgavas iela 1, Riga, LV-1004, Latvia Introduction After EU imposed a ban on the marketing and use of technical polybrominated diphenyl ether (PBDE) formulations, norbornene-based flame retardants such as Dechlorane Plus (DP) and dechlorane–related compounds (DRCs) were regarded as essential alternatives [1]. A number of studies confirmed the presence of DRCs in various environmental objects [2,3] and food products [4,5]. However, human exposure to DRCs via food consumption is still poorly understood and thus the development of reliable methods for their analysis is one of the essential steps to implementing risk assessment strategies. This paper presents an analytical method for the determination of ten DRC representatives in various food samples by using an advanced non-destructive sample preparation procedure, which allows to include acid-labile compounds in the scope of the analysis. Analyte detection with GC-magnetic sector HRMS ensures high selectivity and sensitivity of measurements, while isotope dilution with 13 C-labeled surrogates and internal standardization provides reliable quantification of the compounds of interest. The developed method was extensively validated and applied for the analysis of numerous matrices representing various food types. Materials and methods Chemicals and materials Target analytes and isotopically labeled internal standards were from Cambridge Isotope Laboratories (Tewksbury, MA, USA), Wellington Laboratories (Guelph, ON, Canada), Santa Cruz Biotechnology (Dallas, TX, USA) or from AccuStandard (New Haven, CT, USA). Organic solvents were of analytical grade and were purchased from Sigma- Aldrich (Buchs, Switzerland). Strata SI-1 Silica 500 mg / 6 mL SPE cartridges were obtained from Phenomenex (Torrance, CA, USA), while the Bio-Beads SX3 (200-400 mesh) sorbent was purchased from Bio-Rad (Philadelphia, PA, USA). Sample preparation Aliquots of freeze-dried samples were spiked with 13 C 10 -labeled internal standard solution. The mass of the aliquot depended on lipid content in the sample and was equivalent to approximately 1 g of lipid. The samples were extracted in a Soxtec™ 2055 Fat Extraction System (Hillerød, Denmark) with 1:1 DCM / n-hexane mixture. After the evaporation of extracts, high molecular compounds were removed using LC Tech Freestyle TM GPC system (Dorfen, Germany) on a glass column (50 × 2.5 cm) filled with 50 g of Bio-Beads SX3 stationary phase using 1:1 cyclohexane / ethyl acetate as eluent. The evaporated extracts were dissolved in 1 mL of cyclohexane and applied on the top of Strata Silica 500 mg / 6 mL cartridges, which were preconditioned with cyclohexane. The target analytes were eluted with 10 mL of cyclohexane, concentrated to dryness under a gentle stream of nitrogen, and reconstituted in 50 μL of recovery standard 13 C 12 -PCB 194 solution in nonane prior to instrumental analysis.