Abstract: This paper reports studies on the quantitative method of fluorescent ion pair extraction for the determination of nonfluorescent tertiary amines with a fluorescent reagent sodium 9,10-dimethoxyanthracene-2-sulphonate (MAS). The primary factors, e. g. the effects of pH value of extraction media, quantity of fluorescence reagent and selection of appropriate organic solvent, etc. which influence the ion pair formation and fluorescence intensity are investigated.The following tertiary amines in low concentration range (10^-8～10^-7 mol) are studied, i. e. benethtropine, kemadrine, methylbenethentropine, caramiphen, benztropine, and gangleron. These drugs are dissolved in 4 ml of phosphate buffer (pH 2～4), treated with 1 ml of fluorescent reagent (MAS) (20 mg in 100 ml H₂O), extracted with 6 ml of 1,2-dichloroethane and measured at 25℃ with fluorescence spectrophotometer using excitation and emission wavelength of 383 and 446 nm respectively.The linearity of calibration curve is within the range of 5～100 ng/ml, the detection limit is 1 ng/ml and the coefficient of variation is <5%. The experimental procedure of this method is simple and of high sensitivity, which is 1000 and 100 times higher than that of ultraviolet absorption method and acid dye extraction method respectively.