Di-isopropyl fluorophosphate electrode based on squid nerve tissue

Di-isopropyl fluorophosphatase is contained in the giant axon of squid nerve tissue. This tissue can be coupled with a fluoride ion-selective electrode to produce an electrode selective to di-isopropyl fluorophosphate. The semilogarithmic calibration curve at pH 7.1 is linear over the range 2 × 10^?6?7 × 10^?3 M (RSD < 3% ) with a slope of about 44 mV/decade. The detection limit is 8 × 10^?6 M. The electrode lifetime (with constant response characteristics) is about 16 days.