pH 4.01 is a common low-range pH meter calibration point. All Environmental Express pH buffer solutions are manufactured under ISO 9000 quality guidelines and traceable to NIST standard (for meters with 0.01 resolution). A pH/temperature table is printed on the label for accurate calibrations.

pH 4.01 buffer solution is colored red for visual reference. It is sold in individual 3.8L (1 gal.) bottles and available in cases of four. If unopened, shelf life of pH 4.01 is 2 years.

Store buffers away from direct sunlight.