ACCURACY AND PRECISION IN-VITRO OF BEETRODE(R) MICROELECTRODES USED FOR INTRAORAL PH MEASUREMENTS

The accuracy and precision of 12 different microelectrodes were assess ed through a series of pH recordings of buffer solutions with known pH values. Some electrodes were quite accurate, yielding an average devi ation of recordings from true. values of about 0.05 pH units, while ot her electrodes yielded average deviations of up to 0.20 pH units. The precision of the electrodes also varied between electrodes. While all recordings were within 0.15 pH units from the true values for some ele ctrodes, other electrodes showed a marked dispersion with less than 25 % of the recordings being within 0.15 pH units from true values. For s ome electrodes accuracy depended on true pH values, while no such depe ndency was noted with respect to the precision of the electrodes teste d. Both accuracy and precision may be impaired when pH recordings are made on solutions with pH values outside the pH range encompassed by t he calibration buffers. Our results demonstrate that the accuracy and precision of these microelectrodes cannot be considered fixed and know n parameters. Electrodes should therefore be checked prior to clinical use, and electrodes with low accuracy and precision should be exclude d from further use.