DETECTION AND CORRECTION OF MULTIPLICATIVE INTERFERENCES IN SINGLE-LINE FLOW-INJECTION ANALYSIS WITH FLUORESCENCE DETECTION

Quenching and inner-filter Interference effects in fluorescence measurements were investigated with a single-line flow injection analysis system interfaced to a microcomputer for data collection, control, and data manipulation. A reference peak profile due to physical dilution was obtained by injecting a quinine sulfate (QS) solution and compared with peak profiles of sample solutions to evaluate the effect of concentration dependent interferences. The distortion of the peak profile due to multiplicative Interferences Is detected by a variation in the ratio of the reference to sample signals throughout the sample zone. An empirical function, which Involves a normalization for different analyte concentrations, is described and used to generate correction plots based on the distortion of the profile. Application of the method is demonstrated for the determination of QS with K2Cr2O7 (absorber) and KI (quencher) as Interferants. Errors due to these interferents as small as 0.5% can be detected, and errors larger than 30% can be reduced to less than 2%. © 1990, American Chemical Society. All rights reserved.