Determination of pH by Flow Injection Analysis and by Fiber Optrode Analysis

摘要

Two new procedures for measuring pH have been developed. The first measures pH colorimetrically using a proprietary indicator dye mixture in a flow injection analysis (FIA) procedure. The second measures pH using a fiber optic chemical sensor (FOCS) specifically developed for pH determinations. The FOCS method measures pH by monitoring the fluorescence of a fluorescein derivative bonded to the distal end of a fiber optic cable called an optrade. The FIA method currently has a precision and accuracy of about + or - 0.2 pH units and can measure 100 samples/hour. The FOCS method has a precision of + or - 0.05-0.20 pH units and an accuracy of + or - 0.1 to 0.6 pH units. About 10 to 60 samples can be analyzed. The characteristics of the FOCS Method will vary significantly with individual optrodes. The experimental results indicate that either flow injection analysis or fiber optic chemical sensor analysis could form the basis for an alternative to electrometric measurement of pH in certain circumstances.