DETERMINATION OF ZINC IN SEAWATER USING FLOW-INJECTION ANALYSIS WITH FLUOROMETRIC DETECTION

A sensitive technique for the shipboard determination of zinc in seawa ter has been developed. The technique couples flow injection analysis with fluorometric detection (FIA-FL). A cation exchange column was use d to separate zinc from interfering alkali and alkaline earth ions and to concentrate Zn from seawater. The organic indicator ligand, p-tosy l-8-aminoquinoline, was used to form a complex with zinc, the fluoresc ence of which was determined with a flow-through fluorometer. The dete ction limit (defined as three times the standard deviation of the blan k, n = 4) was 0.1 nM for a 4.4-mL sample. The precision based on the r eplicate analysis of samples containing 4.3 nM Zn was +/-6% (n = 5). A single sample can be analyzed in 6 min. The technique was determined to be accurate on the basis of analysis of the standard seawater solut ions CASS-2 and NASS-2 and by comparison with previous reliable invest igations. A typical profile of 12 samples along with standards and bla nks can be completed in triplicate in 5.5 h.