Determination of trace copper in seawater by flow injection catalytic spectrophotometry

It is found that the copper can catalyze the fading reaction of neutral red reduced by hydrogen peroxide using the alanine as a sensitizer in NH4Cl-NH3·H2O medium(pH 8.0).On the basis of this,a new flow injection catalytic spectrophotometric method was proposed for online determination of trace copper in seawater.Beer's law is obeyed in the concentration range of 2.0-32.0 μg/L for copper.The relative standard deviation of 1.3% was obtained by injecting 10.00 μg/L copper standard solution(n=14).The detection limit calculated from three times of the average background noise was 0.12 μg/L.The recoveries for determining copper in seawater samples were between 97.2% and 105.2%.