Because the fiber-optic chemical sensors based on the fluorescence quenching has an adjustable short distance from the membrane to the end of fiber optics, forming a space of microcell, a diminution of fluorescence is induced by inner filter effects, involving absorption of both excited light from the light source and emited light from the membrane. If the absorption spectra of analytes overlap the fluorescence excitation and/or emission spectra of the fluoroprobe in the membrane, the quenching signal of the fiber-optic chemical sensors would be produced by the resonance energy transfer. In addition, dynamic quenching happens to some haloid, heavy metal compounds and aromatic nitro organic compounds. According to the structural characterization of the fiber-optic chemical sensors based on fluorescence quenching and the mechanism of fluorescence multiple quenching, a non-linear mathematical model was deduced and described for the quantitative analysis model for the fiber-optic chemical sensors. a multiple model regression technique for the quantitative analysis model was reported to provide rapidly and directly the relations be tween the response signal and the concentration of analytes and establish linear regression equation for predicting the concentration of analytes. the technique was applied to fit best mathematical model from the control samples of the therapeutic drugs based on the response of fiber-optic chemical sensors, such as metronidazole, nitrofurantoin and ofloxacin. The pyrenebutyric acid was chosen as a fluoroprobe for constructing the fiber-optic chemical sensor to response the samples. the experimental results showed that these models had some good characteristics and gave an alternative method for establishing quantitative analysis models for the fiber- optic chemical sensors.

Key words: OPTICAL WAVEGUIDE FIBER, MATHEMATICAL MODELS, SENSORS