Reverse flow injection analysis method for catalytic spectrophotometric determination of iron in estuarine and coastal waters: A comparison with normal flow injection analysis

► Catalytic spectrophotometry was coupled to reverse flow injection analysis for iron determination. ► Double carrier streams were used in reverse flow injection analysis. ► An intercomparison experiment with normal flow injection analysis was conducted. ► The concentrations of total dissolvable iron in surface seawater of the Pearl River Estuary were obtained and non-conservative mixing processes were revealed. ► The rFIA method was more sensitive, faster and more environment-friendly.