A renewable liquid drop sensor for di- or trinitrophenol based on fluorescence quenching of 3,3 ',5,5 '-tetramethylbenzidine dihydrochloride

A novel renewable liquid drop sensor is proposed for the execution of a sen sitive, simple and rapid assay. The dynamically growing and falling drops a re formed at the bottom tip of a silanized silica capillary tube connected to the end of a flow system. The feasibility of the proposed method was dem onstrated by performing the fluorimetric determination of di- or trinitroph enol by using 3,3',5,5'-tetramethylbenzidine dihydrochloride (TMB-d) as sen sing reagent. The optimum analytical conditions were established. The senso r shows linear responses in the measuring ranges from 2.45 x 10(-7) to 5.0 x 10(-5) mol l(-1) 2,4-dinitrophenol and from 1.07 x 10(-7) to 8.0 x 10(-6) mol l(-1) 2,4,6-trinitrophenol, and has detection limits of 1.0 x 10(-8) m ol l(-1) for 2,4-dinitrophenol and 4.0 x 10(-9) mol l(-1) for 2,4,6-trinitr ophenol. The analysis is simple and rapid and consumes only micro-amounts o f reagent and sample. The sensor was applied to the direct determination of 2,4-dinitrophenol in synthetic water samples and the indirect assay of qui nine through quantitative precipitation with 2,4,6-trinitrophenol. The resu lts were in good agreement with those obtained by another method.