Determination of Sub-Nanomolar Manganese in Seawater Using Sequential Injection Chemiluminescence Detection with Nitrilotriacetic Acid (NTA) Resin for Matrix Separation

A novel sub-nanomolar Mn(II) determination method is reported, which integrates sequential injection analysis (SIA), chemiluminescence (CL) detection, and a nitrilotriacetic acid (NTA) resin column. Using the SIA technique reduces the consumption of reagents and samples to only 600 and 100 μL per analysis, respectively. Incorporating an NTA resin column eliminates the need for pH adjustment during the measurement process. Under optimized conditions, the detection limit of 0.17 nmol L⁻¹ and a linear calibration between CL intensity and Mn(II) concentrations (0-100 nmol L⁻¹) was achieved. This method was applied to the certified seawater reference material NASS-7 and real seawater samples.