Bromine water

HPLC-grade organic solvents were exclusively used in this study. N-hexane ethyl acetate, methanol were supplied by Sigma-Aldrich (Belefonte, PA, USA). Anhydrous sodium sulphate, hydrogen bromide, potassium bromide, bromine water, acetic acid, zinc acetate, hexacyanoferrate, sodium thiosulphate, borate buffer pH 8 of p. a. grade were supplied by Chempur (Piekary Slaskie, Poland). Florisil (60-100 mesh), triethylamine were supplied by Sigma-Aldrich. C18 (500 mg, 6 ml), Strata X-C (150 mg, 6 ml), Bond-Elute Plexa PCX (200 mg, 6 ml) solid phase extraction cartridges (SPE) were supplied by Agilent Technologies (Santa Clara, CA, USA) and Phenomenex (Torrance, CA, USA). Water used in the laboratory procedures was purified using Hydrolab water purification system (Wiślina, Poland). Certified reference material of acrylamide in rusk (ERMBD274, BAM, Berlin, Germany) was supplied by Sigma-Aldrich. Native and deutered (D 3 ) AA standards were supplied by Sigma-Aldrich. Standards were prepared in ultrapure water. AA certified reference material ERMBD274 was supplied by Sigma-Aldrich. Carrez solution #1 was prepared by dissolving 106 g of potassium hexacyanoferrate trihydrate in 1000 ml of water. Carrez solution #2 was prepared by dissolving 219 g of zinc acetate dihydrate in 1000 ml of water.