What is drift?

The term Drift refers to the background moisture in the titration vessel. This could be caused by ingress of atmospheric moisture, chemical reactions between different samples or gradual breakdown of the reagents. Vast majority of high drift values are caused by the titration cell walls and generator electrodes not being cleaned and dried sufficiently. The drift value is normally displayed in micrograms of water per minute. This additional count is automatically subtracted and is assumed to be constant for the duration of the titration. For this reason, the rate of change of the drift value is more important than the actual value itself. Although it is possible for the titrator to be used at high drift values, it is advisable to wait until the drift value is below 20 mg/minute, and stable, before commencing, especially for low water content samples in the ppm ranges. The lower, and more stable the drift – the more accurate the result.

Posted in: Theory