pH 2.0 Standard @ 25°C

2-Ethyl-3,(5/6)-dimethylpyrazine, Isomer mixture, 1000µg/mL, Solvent-isooctane, Unit 1mL, # of units-, Cas.no. 27043-05-6 or 55031-15-7

Chlorite (ClO2-)

2,4-Dihydroxybenzophenone-13C6, 50µg/mL, Solvent-methanol, Unit 1mL, # of units-1, Cas.no. 131-56-6 (unlabelled)