Flow Injection Analysis System for Conductometric Measurement of Sugar Content

Study on Electrochemical Measurement of Sugar Content of Food, Part VII

Abstract

A conductometric flow injection analysis system for measuring sugar content in food was constructed and several component of this system were investigated. The controlled-current four-electrode method was used for conductance measurements, and then the cell constant of this system was not affected by flow rate (0-5ml·min-1). The most preferrable conditions for optimum operation of the system were as follows: mixing coil length 80cm (i. d.=0.8mm), injection volume 0.68ml, flow rate 2.3ml·min-1. Over the range of 5 to 30% (w/w), the linear response was obtained and the coefficient of variation was 0.20% at 20% (w/w) sucrose for 10 successive assays. The measuring time was about 3min for each of these assays. The sugar content in citrus juice estimated with this system agreed with that obtained from phenol-sulfuric acid method within an error of 0.20% (w/w).