13 c syn dp

Standards of BDE-28, -49, -47, -99, -100, -153, -154, -138, -183, and -209, 1,2-Bis(2,4,6tribromophenoxy)ethane (BTBPE), syn-DP and anti-DP isomers, 2-ethylhexyl-2,3,4,5 tetrabromobenzoate (TBB), 2,3,4,5-tetrabromophthalate (TBPH), hexabromobenzene (HBB), dechlorane-602 (Dec-602), dechlorane-603 (Dec-603), isotopically labelled internal standards (IS) 13 C-BDE-209, 13 C-TBPH, 13 C-TBB, 13 C-syn-DP, and 13 C-anti-DP were purchased from Wellington Laboratories (Guelph, ON, Canada). Recovery standard (RS) CB-207 was purchased from Dr. Ehrenstorfer Laboratories (Augsburg, Germany). Polypropylene (PP) tubes (15 mL) were obtained from Greiner Bio-one (Belgium). Empty PP cartridges (25 mL) were purchased from Grace (Lokeren, Belgium), while Florisil® cartridges (500 mg, 3 mL) and empty PP cartridges (6 mL) were purchased from Supelco (Bellefonte, PA, USA). Silica gel, anhydrous sodium sulphate (Na 2 SO 4 ) and concentrated sulfuric acid (H 2 SO 4 , 98%) were purchased from Merck (Darmstadt, Germany). All solvents were of chromatography grade: n-hexane was purchased from Acros Organics (Belgium); dichloromethane (DCM), iso-octane, toluene and acetonitrile (ACN) were purchased from Merck.

The frozen egg, muscle and gonad samples were homogenised with anhydrous Sodium sulfate (Na2SO4) (Merck) using a stainless steel/glass 1 L laboratory blender (neoLab Rotorblender).
Prior to extraction all samples were spiked with mass labelled surrogate standards 13 C-BDE-28, 13 C-BDE-47, 13 C-BDE-99, 13 C-BDE-153, 13 C-BDE-183, 13 C-MeOBDE-47, 13 C-MeOBDE-100, 13 C-HBB, 13 C-synDP and 13 C-PBBz (Wellington Laboratories, Cambridge Isotopes).
Extraction and clean-up were performed in accordance with the method described in Sühring et al. (2013) (link), using accelerated solvent extraction with subsequent gel permeation chromatography and silica gel clean-up. 500 pg (absolute) 13 C-PCB-141 and 13 C-PCB-208 was added as an injection standard to each sample. The lipid content of samples was determined gravimetrically from separate aliquots following a method described in Sühring et al. (2013) (link). 2 x 200 L tank water of the recirculation tank for the hormone treated eels was enriched on PAD3 sorbent filled glass cartridges at 1 mL per minute. Surrogate standards were added (see above) prior to extraction. Extraction and clean-up was performed using a method by Möller et al. (2010) . The water samples were analysed for all studied compounds.
The aqueous salmon pituitary extract (SPE) was ultrasonic extracted with 2:1 hexane:SPE (v/v) for 2 x 15 minutes and analysed.