Buffer solution

General description
This red-colored citric acid/sodium hydroxide/hydrogen chloride buffer solution is gravimetrically prepared at a registered calibration laboratory with high-quality reagents and water. Its pH value of 4.00 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 is temperature dependent 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.
Application
The buffer is used as a standard to calibrate pH measuring instruments or pH electrodes and as a control to measure the pH of other solutions.
Features and Benefits
Measured and qualified at an ISO/IEC 17025 and ISO 17034 accredited laboratory
Traceable to secondary reference standard from NIST and primary certified reference standard from PTB
Available in a secure 500 mL plastic bottle and 4 L innovative and sustainable Titripac® PE/Aluminum packaging for a reduced waste generation
Accompanied with a detailed and batch-specific certificate of analysis (CoA) for an effective audit
Product label follows the ISO Guide 31 and contains information about ordering number, article description, lot number, safety data, and expiry date
Packaging material subjected to comprehensive stability studies as per ISO Guide 35
An uncertainty of +/- 0.02 in the pH value at 25°C
Legal Information
CERTIPUR is a registered trademark of Merck KGaA, Darmstadt, Germany
Titripac is a registered trademark of Merck KGaA, Darmstadt, Germany