Merck, 1.99022.4000, Buffer Solution

The di-sodium hydrogen phosphate/sodium hydroxide buffer solution is gravimetrically prepared at a registered calibration laboratory with high-quality reagents and water. Its pH value of 12.00 at 25°C is measured using a combined glass electrode following a 5-point calibration method. The measurement is made following DIN 19268 using reference buffer solutions compliant to DIN 19266, NIST, IUPAC, Ph. Eur, and USP. The buffer pH strongly depends on the temperature and therefore a constant temperature must be maintained during its use. Please visit ISO certificates and Site Quality Self-Assessments to access the current certificates of accreditation. Download your certificate at http://www.sigma-aldrich.com to view certified values, including uncertainty and expiry date.