tris(Hydroxymethyl)aminomethane White solid. Useful in the pH range of 7.0-9.0. Has a pKa of 8.1 at 25°C. Purity: ≥99% by titration test (perchloric acid titration). Contaminants: RNases, DNases, proteases: none detected. Absorbance (260 nm): ≤0.03; (280 nm): ≤0.02. Heavy metals: ≤0.0005%. pKa 8.30 at 20°C. RTECS TY2900000, CAS 77-86-1. Merck Index: 14, 9772
R: 36/38; S: 26 | 
