ASSESSMENT OF DIFFERENT FLUOROMETRIC REACTIONS FOR CYANIDE DETERMINATION IN FLOW SYSTEMS

Several fluorimetric reactions for the determination of cyanide by mea ns of flow injection systems were tested, The first reaction is based on the displacement of 8-hydroxyquinoline-5-sulfonic acid (HQS) from t he Pd(HQS)(2) complex by cyanide ion and the subsequent reaction of fr ee HQS with Mg-II to form a fluorescent species, Secondly, the inhibit ory effect of cyanide on the reaction between iodine and fluorescein w as also evaluated as a method to quantify cyanide, The third method is based on the detection of an isoindole derivative formed by the react ion of o-phthalaldehyde (OPA) or 2,3-naphthalenedialdehyde (NDA) with glycine in the presence of cyanide, Chemical and hydrodynamic paramete rs mere optimized for each system and the analytical performance of th e methods was established, Detection limits of 5 mu g l(-1) (fluoresce in-iodine method), 0.40 mu g l(-1) (Pd-HQS-Mg method), 0.25 mu g l(-1) (OPA method) and 0.03 mu g l(-1) (NDA method) were obtained.