Accurate pH analysis is critical in Food Processing areas and Laboratory settings. Small variances may impact food quality, safety, shelf-life, flavor and consistency. All pH electrodes should be calibrated to pH meters with fresh, unused calibration buffers that bracket the pH value of the product being tested.
For food samples that have a pH range between 4 and 7, electrodes should at a minimum be calibrated using 4.01 and 7.00 pH calibration buffers. Electrodes for samples between 1.68 and 4 should be calibrated with 1.68 and 4.01 pH buffer. For samples between 7 and 10 pH, buffers 7.00 and 10.01 pH are recommended. Also available is 12.46 pH buffer for very high pH products.
Listed above are the most common pH calibration buffers (1.68, 4.01, 7.00, 10.01 & 12.46 pH at 25°C) and many pH meters automatically recognize these values during a calibration procedure. Although not used for calibration, Nelson-Jameson also has 5.00 pH buffer available that is commonly used as a control check for products around 5 pH.
Because of the composition of 10.01 and 12.46 pH buffers, once the original ship container is opened it is best to use within 2-4 months. Other pH buffers are not as adversely affected but as a good practice should be used within 6-months once the original container is opened. Buffers should be stored in areas that block sunlight. The expiration date on containers of pH calibration buffers is valid for any that have not been opened.