Sodium arsenate dibasic heptahydrate

All reagents used were of analytical grade. All solutions were prepared using ultra-high pure (UHP) 18 Ω water. All laboratory ware was soaked for 24 h in an acid bath containing 10% (v/v) nitric acid and then rinsed with UHP water. Concentrated hydrochloric acid (12 mol L⁻¹), HNO₃ 69%, NaCl, NH₄Cl, anhydrous Na₂SO₄, CaCl₂.2H₂O, NaHCO₃, anhydrous D ( + )-glucose, sodium arsenate dibasic heptahydrate, cadmium acetate and lead acetate trihydrate were obtained from Fisher Scientific. d-glucuronic acid, Pancreatin (pig), pepsin (pig), Bovine serum albumin (BSA), KSCN, NaH₂PO₄, mucin (pig), D-glucosamine hydrochloride, lipase (pig), α-amylase (Bacillus species), urea and bile salts (bovine), modified eagle medium (DMEM) containing 4.5 g/L glucose, penicillin-streptomycin solution (10, 000 units penicillin and 10 mg streptomycin per mL), and Hank’s Balanced Salt Solution (HBSS) and glycine were obtained from Sigma–Aldrich (St. Louis, MO, USA). KH₂PO₄, MgCl₂·6H₂O, KCl, and uric acid were obtained from VWR. Caco-2 cells (HTB-37™) were purchased at passage 18 from the American Type Culture Collection (ATCC, Manassas, VA, USA). Fetal bovine serum and trypsin-EDTA were purchased from Invitrogen (Burlington, ON, Canada).

Sodium arsenite, sodium arsenate dibasic heptahydrate (≥98%), methanol (Optima^TM for HPLC), tert-butanol (t-BuOH), acetonitrile (HPLC grade), o-phosphoric acid (85%, ACS grade), formic acid (88%), ammonium hydroxide (29.2%), and ferric chloride hexahydrate (FeCl₃·6H₂O, 98.8%) were purchased from Fisher Scientific (Waltham, MA, USA). Ferrous chloride tetrahydrate (FeCl₂·4H₂O, ≥99%), humic acid sodium salt (Lot#STBC5468V), coumarin (COU) (≥99%), potassium sorbate (≥99%), and 7-hydroxycoumarin (7-HC) (99%) were obtained from Sigma Aldrich (St. Louis, MO, USA). Furfuryl alcohol (FFA) and the tetrabutylammonium hydroxide (TBAH) (40 wt.%) were purchased from Acros Organic (Geel, Antwerp, Belgium). The 2,4,6-trimethylphenol (98%), was obtained from TCI (Portland, OR, USA). The malonic acid (reagent grade, 99.5%) was purchased from Alfa Aesar (Haverhill, MA, USA). Millipore water (MilliQ water, resistivity~18.0 MΩ cm⁻¹ at 25 °C) was used for sample and standard preparation unless otherwise indicated.