A shipboard method for catalytic kinetic spectrophotometric determination of trace Cu(II) concentrations in seawater using reverse flow injection analysis coupled with a long path length liquid waveguide capillary cell

•An on-line automated method was developed for monitoring trace Cu(Ⅱ) in seawater.•The method possessed low detection limit and wide linear range.•The method was free of the carry-over effect and interference of nine co-existing ions.•Field applications were successfully carried out to prove the method practicability.