Towards chemiluminescence detection in micro-sequential injection lab-on-valve format: A proof of concept based on the reaction between Fe(II) and luminol in seawater

Oliveira, Hugo M., Grand, Maxime M., Ruzicka, Jaromir and Measures, Christopher I. (2015) Towards chemiluminescence detection in micro-sequential injection lab-on-valve format: A proof of concept based on the reaction between Fe(II) and luminol in seawater. [in special issue: 18TH ICFIA (2013)] Talanta, 133, 107-111. (doi:10.1016/j.talanta.2014.06.076).

Abstract

Micro-sequential injection lab-on-valve (µSI-LOV) is a well-established analytical platform for absorbance and fluorescence based assays but its applicability to chemiluminescence detection remains largely unexplored. In this work, we describe a novel fluidic protocol and two distinct strategies for photon collection that enable chemiluminescence detection using µSI-LOV for the first time. To illustrate this proof of concept, we selected the reaction between Fe(II) and luminol and developed a preliminary protocol for Fe(II) determinations in acidified seawater. The optimized fluidic strategy consists of holding 100 µL of the luminol reagent in a confined zone of the LOV and then displacing it with 50 µL of sample while monitoring the chemiluminescent product. Detection is achieved using two strategies: one based on a bifurcated optical fiber and the other based on a customized detection window created by mounting a photomultiplier tube atop of the LOV device. We show that detection is possible using both strategies but that the window strategy yields significantly enhanced sensitivity (355×) due to the larger detection area. In our final experimental conditions and using window detection, it was possible to achieve a limit of detection (LOD) of 1 nmol L?1 and to quantify Fe(II) in acidified seawater samples up to 20.00 nmol L?1 with high precision (RSD<6%). These analytical features combined with the long-term stability of luminol solution and the full automation and low reagent consumption make this approach a promising analytical tool for shipboard analysis of Fe(II). The intrinsic capacity of the LOV to operate at a low microliter level and to handle solid phases also opens up a new avenue for chemiluminescence applications. Moreover, this contribution shows that LOV can be a universal platform for optical detection, capable of absorbance, fluorescence and luminescence measurements in a single instrument setup.

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Contributors

Author: Maxime M. Grand

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