Determination of dissolved zinc in seawater using micro-Sequential Injection lab-on-valve with fluorescence detection

Grand, Maxime, Oliveira, Hugo M., Ruzicka, Jaromir and Measures, Christopher (2011) Determination of dissolved zinc in seawater using micro-Sequential Injection lab-on-valve with fluorescence detection. Analyst, 136 (13), 2747-2755. (doi:10.1039/c1an15033b).

Abstract

This paper introduces the preliminary design and optimization of a micro-Sequential Injection lab-on-valve system (?SI-LOV) with fluorescence detection for the direct determination of trace Zn2+ in an unacidified seawater matrix. The method capitalizes on the sensitivity and selectivity of FluoZin-3, which was originally designed to measure zinc in living cells. The optimum reaction conditions, sources of blank signal and physical parameters of the ?SIA-LOV are evaluated with the requirements of trace metal analysis in mind, namely high sensitivity and low background signals. A detailed investigation of the effect of sample and reagent sequencing on sensitivity is presented for the first time using ?SIA-LOV. We find that the order of sequencing greatly influences peak shape and analytical sensitivity with the highest and smoothest peaks obtained when a large volume of sample (75 ?L) is aspirated last in the sequence prior to flow reversal and detection. The optimized reaction conditions and reagent/sample sequencing protocol yield a detection limit of 0.3 nM Zn2+, high precision (RSD < 2.5%), a linear quantification range up to 40 nM and an analytical cycle of [similar]1 min per sample. This work demonstrates that ?SI-LOV is capable of attaining detection limits that are close to those needed for open ocean determinations of Zn2+ without preconcentration or separation of the analyte from the seawater matrix. The low reagent consumption (50 ?L per sample), full automation and minimal maintenance requirements of ?SI-LOV make it well suited for shipboard analysis and, eventually, for development to meet the pressing need for trace element measurements in unattended locations.

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Contributors

Author: Maxime Grand

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