Ricca Chemical Company 1550-16 Buffer, Reference Standard, pH 7.00, 500 mL is intended for standardization of pH meters. The specification on Ricca Buffer, pH 7.00 is plus-or-minus 0.01 at 25 degrees Celsius. Ricca does not use formaldehyde or mercury compounds as preservatives, or chromium compounds as colorants, making our buffers safer to use and easier to dispose of. This buffer is certified traceable to NIST Standard Reference Material, lot numbered and expiration dated.