Instrumentation and Automated Photometric Titration Procedure for Total Acidity Determination in Red Wine Employing a Multicommuted Flow System

摘要

An automated procedure for photometric titration of red wine and associatedinstrumentation is described. The procedure was based on the flow-batch approachimplemented employing multicommutation. The photometric detection was carried outusing a homemade LED-based photometer. The mixing device, LED, and photodetectorwere attached to the titration chamber in order to form a compact and small-sized unit. The flow system comprised an automatic injector and three-way solenoid valves, which werecontrolled by a microcomputer through an electronic interface card. The software, writtenin Quick BASIC 4.5, was designed with abilities to accomplish all steps of the titrationprocedure including data acquisition and real-time processing to decide about the course of titration in the following step and so forth, until the titration endpoint was reached. The usefulness of the proposed titration system was demonstrated by analyzing red wine samples. When results were compared with those obtained using the AOAC referencemethod, no significant difference was observed at the 95% confidence level. A relativestandard deviation of ca  2% (n=9) was obtained when processing a typical red wine sample containing 7.3 gl -1 total acidity expressed as tartaric acid.