A method for the determmatlon of methamphetamme m urme usmg a methamphetamme-sensltlve membrane electrode was developed No pretreatment of urme samples was required, which enabled methamphetamme excreted m the urme of drug addicts to be assayed sensltlvely and selectively The electrode was constructed by mcorporatmg sodmm tetralus[3,5-b~trdluoromethyl)phenyl&orate as the Ion exchanger and tncresyl phosphate as the membrane solvent m a poly$nnyl chloride) membrane matnx The detection hrmt for methamphetamme m urme was 10 PM The response charactenstlca were affected conslderably by changmg the membrane solvent and tncresyl phosphate was found to be the most smtable for the determmatlon of methamphetamme m urme Keywords Ion selective electrodes, Potentlometry, Membrane electrodes, Methamphetamme, Urme Methamphetamme 1s known to stimulate central nervous system actlvlty, it has a slgmflcant potential for abuse and tolerance and its dependence-producing property leads to psycholo@cal dlsmtegratlon [l] In Japan, the use of this drug 1s regulated by the Stmmlant Drugs Control Act passed m 1951 Nevertheless, methamphetamme abuse 1s still endemic m Japan Therefore, the detection of methamphetamme m the urme of offenders, which 1s analysed most commonly by gas chromatography-mass spectrometry or mfrared spectrometry after extraction of methamphetamme from the urme with an orgamc solvent, followed by punficatlon by thm-layer chromatography [l], forms a large part of the work-Correspondence to T Katsu, Faculty of Pharmaceutical SCIences, Okayama Umvernty, Tsushlma-naka, Okayama 700 (Japan)