Portable analyser using two-dimensional ion chromatography with ultra-violet light-emitting diode-based absorbance detection for nitrate monitoring within both saline and freshwaters

•Two-dimensional rapid IC with on-column matrix elimination for seawater analysis.•Selective, rapid and direct detection of nitrite and nitrate in freshwater.•Deep UV LED based optical detection for nitrate determination.•Automated dual-functionality for alternative analysis of freshwater or marine waters.•Analytical performance comparable to accredited instrumentation.