D3 6 acetylmorphine

MG chloride (>96.0%) and LMG (>98.0%) analytical standards were obtained from Sigma Aldrich (St Louis, MO, USA). MG oxalate technical grade standards used for trout exposure was obtained from Fisher Scientific (Waltham, MA, USA) and for shrimp exposure, Acros Organics (Geel, Belgium). Labelled internal standards, d3-diphenhydramine and d3-6acetylmorphine, were purchased from Cerilliant (Round Rock, TX, USA). HPLC grade acetonitrile, methanol, water, LC-MS grade formic acid, acetic acid and ammonium acetate were obtained from Fisher Chemical (Pittsburgh, PA, USA). Anhydrous magnesium sulfate and sodium acetate were purchased from Sigma Aldrich (St Louis, MO, USA). Primary secondary amine (PSA) sorbent was purchased from Agilent (Santa Clara, CA, USA). All glassware used was baked in an oven at 320°C for four hours and rinsed with methanol before use. Labelled mL was prepared in methanol and stored at -20°C in amber vials. MG and LMG standards of 1 mg/mL and working standards of 20 were prepared in methanol and stored at -20°C in amber vials. All standards were prepared fresh every 6 months.
Five calibration standards, from 3 to 20 ng/mL, were prepared in water (0.1% formic acid).