Local anesthetics measured by lipophilic beta-cyclodextrin-based ion-selective electrodes

2,3,6-Trioctyl and 2,6-didodecyl-beta-cyclodextrins have been incorporated in ion-selective electrodes as neutral ionophores for the detection of the local anesthetics procaine, prilocaine, lidocaine and bupivacaine hydrochlorides. Nernstian response and excellent limits of detection were observed (-log [C] greater than or equal to 5.0). Interference from 'serum' levels of sodium, potassium and calcium (150.0 mmol dm(-3) Na+, 1.26 mmol dm(-3) Ca2+ 4.30 mmol dm(-3) K+), was negligible (-log K-ij(pot)) (overall) greater than or equal to 4.0). The major organic interferents were molecules of similar size and structure which caused reduced slope and drift in baseline potentials at 10 mmol dm(-3) levels of concentrations. However, the interferences were substantially reduced when the interferent concentration was reduced by a factor of 10. Nernstian response was maintained in the presence of bovine serum albumin (BSA), serum (HS) and alpha(1) acid glycoprotein (AAG). A polyurethane, (Tecoflex SG80) membrane matrix was more biocompatible when compared to PVC as evidenced by lower E(0) (internal) shifts with the former.