DPAN光纤化学传感器过程分析水中微量Cr(Ⅵ)的研究

STUDY ON THE PROCESS ANALYSIS FOR Cr(Ⅵ) IN WATER WITH OPTIC FIBRE-CHEMICAL SENSOR BASED ON FLUORESCENCE MULTIPLE QUENCHING OF DIPHENYLANTHRACENE (DPAN)

研究了基于荧光多元猝灭响应原理的DPAN光纤化学传感器在线测定Cr(Ⅵ)的方法。敏感膜配方为0.3μmolDPAN,该膜性能稳定,测定Cr(Ⅵ)的响应机制以动力学猝灭和共振能量转移为主,膜和光纤端部的间距为6mm,采用001×7号阳离子交换树脂排除干扰,流速为3 0ml·min-1,建立了过程分析Cr(Ⅵ)条件。DPAN FOCSMQ和PC机联用测定Cr(Ⅵ),线性范围为0～10μg·ml-1,检出限为0.087μg·ml-1,日内和日间精密度<5.3%,回收率在97.0%～104.0%之间,测定工业电镀废水样品的Cr(Ⅵ)获得满意结果。

A method for on-line determination of Cr(Ⅵ) based on the phenomenon of multivariate fluorescence quenching (MFQ) of DPAN was studied. The optimum amount of DPAN in the sensing membrane is reported to be 0.3μmol. The DPAN membrane showed good stability in the measurement. The mechanism of response of the DPAN-membrane to Cr(Ⅵ) was found to be mainly of kinetic-quenching (KQ) and resonance energy transfer (RET). The distance between the membrane and the end of the optical fibre was set at 6mm. Interferences in the determination were eliminated by passing through the cation exchange resin (NO. 001×7) column at a flow-rate of 3.0ml·min^(-1). A process analyzer in hyphenation with PC microprocessor was designed as shown in the schematic diagram (Fig. 1) for the determination of Cr(Ⅵ). The analyzer is abbreviated as DPAN-OS-MFQ-PC. Linear range of determination of Cr(Ⅵ) was kept in the range 0～10μg per ml of solution, and the limit of detection was found to be 0.087μg·ml^(-1). The RSD′s (n=6) found in within-day measurements and in between-days measurements were less than 5.3% and the recoveries in the range of 97.0%～104.0% were found. The method and the analyzer have been applied satisfactorily in the process analysis of electroplating waste water.