Fast direct determination of strontium in seawater using high-performance chelation ion chromatography

A new method for the fast direct chromatographic determination of strontium in seawater has been developed. Two coupled silica monolithic columns (total dimensions 200 × 4.6 mm I.D.) chemically modified with iminodiacetic acid (IDA) functional groups were used for baseline separation of all alkaline-earth metals in seawater in less than 4 min at flow rate of 4.0 mL min− 1, using an eluent containing 0.25 M sodium chloride and 2 mM glycolic acid, pH 5.11. Several colour-forming ligands, including o-cresolphthalein complexone (o-CPC), methylthymol blue (MTB), xylenol orange (XO), 4-(2-pyridylazo)resorcinol (PAR) and ZnEDTA–PAR were evaluated as reagents for post-column reaction (PCR) based spectrophotometric detection. Sensitivity of the developed method for strontium was at the low mg L− 1 level in undiluted seawater samples, in the presence of excessive amounts of calcium and magnesium, using post-column reaction detection with o-CPC at 570 nm. The method allowed quantitative determination of strontium in seawater samples (LOD 3.23 ± 0.15 mg L− 1, sr = 4.6%), with direct injection of just 4 μL of seawater onto the chromatographic column.

► A simple HPCIC method allowing fast determination of Sr2+ in seawater is developed.
► For the first time, the determination of strontium in seawater does not require any sample pretreatment.
► This method combines excellent robustness, good reproducibility of the results and the possibility of shipboard analysis.
► The short analysis time with less labor required make this method very useful for the production of concentration profiles.