Review on Biopharm Calibration Traceable Reference Standards by William Stewart

I ordered these buffer solutions to test the accuracy of a small inexpensive pH meter that I bought. In fact, the cost of a pH meter and these buffers were about the same. But anyway, I wanted to test its accuracy. Although it read correctly on initial testing, I noticed that with repeated use there was a gradual drift, with a positive error near 0.2 pH units. When the meter was recalibrated, the readings from these standardized buffers were acceptable again. Although the pH meter comes with buffer packs that must be dissolved to recalibrate before use, it was handy to have an independent set of standard pH buffers to check. I am very happy with them.