pH 2.0 Standard @ 25°C

Azamethiphos, 100 µg/ml, Ethyl acetate, 5ml

Mono-n-butyl phthalate (ring-1,2-13C2, dicarboxyl-13C2, 99%) 100 µg/mL in MTBE, 1,2ml

Sodium Butyrate (C3H7COOH)