A pH buffer is a reference solution of known pH value that is used for sensor calibration. pH buffers are key to ensuring accurate pH readings. Select from our comprehensive range of accurate pH calibration solutions, from technical buffers, buffers certified by an accredited body (DAkkS), to NIST/DIN buffers for high precision. To minimize contamination risk, choose small bottles or single-use sachets.
pH readings are only as accurate as the solutions used for calibration. Our comprehensive portfolio of pH calibration solutions satisfies every accuracy requirement. From technical buffers to pH buffers certified by an accredited body, we have the most suitable buffer for every application.
For high accuracy, uncontaminated buffers are of utmost importance. Our sachets ensure a fresh solution with the appropriate volume to perform a calibration directly in the sachet for maximum ease of use. 250mL bottles enable easy handling and reduce contamination risk in comparison to bulk containers.
A lot-specific certificate of analysis is available for every calibration solution, documenting accuracy and providing traceability to national metrology institutes for quality control. To support compliance with regulations, each SDS (Safety Data Sheet) and label contains information according to GHS (Globally Harmonized System) in local languages. Read more
Thanks to the open magazines of the dispenser box, the number of remaining sachets can be easily determined, even from a distance. A reorder indicator helps to prevent running out of stock.
Our DAkkS certified pH buffers are verified by an independent, ISO 17025 accredited laboratory, providing confirmation of the pH value and associated uncertainty, making them a suitable choice for highly regulated industries.
NIST/DIN pH buffers are manufactured according to DIN/ISO 19266. They are specified to three decimal places, e.g. pH 9.180, offering a low uncertainty (± 0.015 pH).
METTLER TOLEDO provides entire electrochemistry systems - from meters and sensors to calibration solutions and software. Benefit from automatic buffer recognition or temperature dependency tables for automatic accurate temperature compensation.
We support and service your measurement equipment through its entire life-cycle, from installation to preventive maintenance and calibration to equipment repair.
*The tolerances are only for the buffer and not for the entire pH measurement of a sample.
The buffers used for calibration must be selected according to the sample's pH. For instance, if a sample is expected to have a pH of 7.45, the calibration must include pH buffers 7.00 and 9.21 (or similar). Use a minimum of two fresh buffers for calibration.
It is not necessary to include pH 7.00 for calibration according to the US and European pharmacopoeia (USP and EP, respectively). But if the calibration is done in compliance with the Japanese Pharmacopoeia (JP), then a pH 6.86 buffer (phosphate) is mandatory. For calibration according to EP, only pH buffer 4.01 (phthalate) is compulsory. If not working according to any regulation, the principle is easy: For calibration, only those pH buffers are needed which bracket the pH range of your samples. For example, in a quality control where every sample should have a pH between 3.5 and 3.8, a two-point calibration with pH 2.00 and 4.01 is sufficient. There is no need for calibration with pH 7.00 in such a case.
The quality of a solution is only guaranteed for unopened bottles that have not yet expired. The following tips will help optimize the use of pH buffer solutions after opening and while in use in the laboratory. Fresh calibration solutions minimize the measurement uncertainty and thus optimize the reproducibility of results:
The certificates of all calibration solutions and many electrolytes can be downloaded at www.mt.com/buffer. The respective material safety datasheets are available at the same place.
The expiry date indicates the date until which the certificate guarantees the value and the associated measurement uncertainty. After this date the uncertainty cannot be guaranteed. So, it is better to discard expired pH buffer.
Never calibrate directly in the solution bottle. Use a fresh aliquot of pH buffer for each calibration to ensure no contamination enters the bottle.
We offer buffer sachets (small volume packaging of 20mL) that are easy to use and guarantee fresh solutions for every calibration. Each sachet box comes with a printed certificate.
When measuring the pH value of a sample, gently stir the sample to ensure that it is homogeneous. It is important that calibration and measurement are done under the same conditions.
Regular calibrations will lead to more accurate results. Some applications might require a calibration before every measurement, but in general it is enough to calibrate every 24 hours. Always use fresh pH buffers for calibration.