A novel optical chemical sensor based on the dynamic liquid drops combined with flow injection-solid phase has been developed for continuous and sequential determinations of the mixture of Vitamin B-1, Vitamin B, and Vitamin B-6. The design and characteristics of the sensor system are described. The dynamically growing and falling drops serve as windowless optical cells. The adsorption, desorption and quantitative determinations of VB1, VB2 and VB6 were carried out based on selective adsorption of Sephadex CMC-25 and different fluorescence characteristics of VB2, VB6 in the basic solutions. The optimum analytical conditions for compound Vitamin B assay have been established. Under these conditions, linear calibration curves were obtained over the range of 0.01-8.00, 0.01-10.00 and 0.01-3.00 mug/ml for VB1 VB2 and VB6 with the limits of determination of 0.008, 0.005 and 0.006 mug/ml, respectively. This method has been applied in the determination of synthetic mixture of VB1, VB2, VB6 and Vitamin B compound tablets with satisfactory results. The technique, which has been described, provides a simple, effective and sensitive method to assay the biological samples. (C) 2004 Elsevier B.V. All rights reserved.