Which buffer solutions should I use to calibrate my pH meter with?

As you will see on our website, we manufacture a wide range of buffer solutions for a variety of applications. However, for 99% of the time buffer 7 and buffer 4 solution are the two you need to perform a calibration. If you are measuring mostly in the alkaline scale, then you might use buffer 7 and buffer 10, although buffer 10 is not as stable a solution as buffer 4, and therefore has a much shorter life once exposed to air.