VALIDATION OF AN ION-SELECTIVE ELECTRODE SYSTEM FOR THE ANALYSIS OF SERUM FLUORIDE-ION

A high impedance unit was developed for use with a fluoride/pH electro de system for the measurement of serum fluoride. The linearity, accura cy, precision and detection limit of the system is reported. At a pH o f 1.55, the system was linear over a range of serum fluoride concentra tions up to 100 mu mol l(-1), with a lower limit of detection of 0.3 m u mol l(-1). Recoveries at this PH were 94-105% in the range 2.6-100 m u mol l(-1). Within-run CVs ranged from 4.2% at a level of 2.3 mu mol l(-1) to 1.2% at a level of 55.7 mu mol l(-1), while day-to-day CVs ra nged from 12.8% at a level of 2.2 mu mol l(-1) to 4.6% at a level of 5 1.7 mu mol l(-1). The system demonstrated a rapid response lime and ha s the potential for a smaller sample size requirement with alternative electrode shape. Continued development of this unit into an automated fluoride ion selective electrode system is recommended, since the mea surement of Serial serum fluoride samples is of greatest importance in assessing the impact of new anaesthetic agents on renal function.