The buffer solutions are prepared according to precise formulas and are standardised with a pH meter calibrated according to NIST standards.
The sachets contain 20mL of buffer solution which is sufficient to perform a calibration out in the field or away from the laboratory. For situations where it is likely more frequent calibrations will be performed, then CXD can also supply the solution ready to use in bottles ranging from 230ml to 1 Gallon sizes. This can be arranged by contacting CXD.
All pH 4 solutions show batch number, expiration date and the correlation table between pH and temperature and can be ordered with or without certificate of analysis (see listing below).
pH 4 buffer is one of the most commonly used buffer values as it is extremely stable and represents a mid-way point in the pH scale between pH7 (the most commonly used buffer) and end of scale.