Sigma-Aldrich 27102 Citric acid monohydrate puriss., meets analytical specification of Ph. Eur., BP, USP, E330, 99.5-100.5% (based on anhydrous substance), grit Linear Formula: HOC(COOH)(CH2COOH)2 · H2O CAS Number: 5949-29-1 Molecular Weight: 210.14