title: Large volume preconcentration and determination of nanomolar concentrations of iron in seawater using a renewable cellulose 8-hydroquinoline sorbent microcolumn and universal approach of post-column eluate utilization in a Lab-on-Valve system.
abstract: We report on a Lab-On-Valve (LOV) configuration for analyte preconcentration from milliliter sample volumes using confluent mixing in the holding coil for in-line addition of loading buffer. The system was applied to the spectrophotometric determination of iron(II) in acidified seawater using 1,10-phenanthroline as color reagent. A cellulose-based chelating sorbent containing 8-hydroxyquinoline was used for the first time in LOV and excellent retention behavior and loading capacity were found. The flow system employs a syringe pump for handling all solutions (sorbent suspension, loading buffer, water, eluent, and color reagent) and a peristaltic pump for sample propulsion and includes a fit-for-purpose 14 cm long detection glass flow cell and a bubble trap for in-line carrier degasification. Advantage was taken of the LOV flow-through port to keep the eluted analytes for re-aspiration for subsequent chromogenic reaction. In effect, a universal analyzer configuration and preconcentration procedure was developed, which is combinable with other analytes, sorbents, and reagents. Among the studied parameters were the compositions, pH, volumes, and flow rates of loading buffer, eluent, and color reagent, as well as the microcolumn size, repeatability, and system stability. Reproducibility of 4.1% RSD over the entire working range, a LOD of down to 5 nmol L(-1), sampling frequency of 12h(-1), and linearity up to 1 µmol L(-1) for 3.3 mL of sample were obtained and applicability to real samples was demonstrated. It was proven that both Fe(III) and Fe(II) were retained and yielded similar recovery and sensitivity values. The method was applied to coastal seawater samples and spiking experiments yielded recovery values close to 100%.
authors.affiliation: Department of Analytical Chemistry, Faculty of Pharmacy in Hradec Králové, Charles University in Prague, Czech Republic. Electronic address: Horstkob@faf.cuni.cz.
authors.forename: Burkhard
authors.initials: B
authors.lastname: Horstkotte
authors.affiliation: Department of Analytical Chemistry, Faculty of Pharmacy in Hradec Králové, Charles University in Prague, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Chocholouš
authors.affiliation: Department of Analytical Chemistry, Faculty of Pharmacy in Hradec Králové, Charles University in Prague, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Solich
mesh_terms: D053000:Analytic Sample Preparation Methods / Q000295:instrumentation / Q000379:methods*; D002021:Buffers; D002482:Cellulose / Q000737:chemistry*; D002614:Chelating Agents / Q000737:chemistry; D003116:Color; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000032:analysis* / Q000737:chemistry* / Q000302:isolation & purification; D057230:Limit of Detection; D015125:Oxyquinoline / Q000737:chemistry*; D010618:Phenanthrolines / Q000737:chemistry; D015203:Reproducibility of Results; D012623:Seawater / Q000737:chemistry*; D052616:Solid Phase Extraction
chemical_list: D002021:Buffers; D002614:Chelating Agents; D010618:Phenanthrolines; D015125:Oxyquinoline; D002482:Cellulose; D007501:Iron; C025205:1,10-phenanthroline
keywords: 1; 10-Phenanthroline; 8-Hydroquinoline-modified cellulose sorbent; Bead injection; Iron determination in seawater; Lab-on-Valve; Long-path detection cell