Application of the C4.5 classifier to building an expert system for ion chromatography

A classifier based on the philosophy of induction is used to create rules for the choice of a detector for ion chromatography (IC). A data base of over 4000 instances was used to obtain suitable classifications, that were initially compiled for use in Haddad and Jacksonʹs recent monograph on IC. The properties of an ion chromatography method that were used for rule building were solute name, separation mechanism, application, number of solutes, ion class, halide type, sulphate presence, nitrate presence, and whether a suppressor or post column detection was used. The classifier, C4.5, chooses the property that maximises the amount of information gained. By examining properties that relate to a given class, C4.5 operates a top—down induction process. A tree with 62 rules was derived from this data base. The evaluation of these rules against two test sets showed that 70% of the proposed methods were an exact match with the published methods and a further 22% gave practical methods as assessed by our expert.