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Issue 10, 2012
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Determination of Microcystin-LR in waters in the subnanomolar range by sol–gel imprinted polymers on solid contact electrodes

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Abstract

The present work reports new sensors for the direct determination of Microcystin-LR (MC-LR) in environmental waters. Both selective membrane and solid contact were optimized to ensure suitable analytical features in potentiometric transduction. The sensing layer consisted of Imprinted Sol–Gel (ISG) materials capable of establishing surface interactions with MC-LR. Non-Imprinted Sol–Gel (NISG) membranes were used as negative control. The effects of an ionic lipophilic additive, time of sol–gel polymerization, time of extraction of MC-LR from the sensitive layer, and pH were also studied. The solid contact was made of carbon, aluminium, titanium, copper or nickel/chromium alloys (80 : 20 or 90 : 10). The best ISG sensor had a carbon solid contact and displayed average slopes of 211.3 mV per decade, with detection limits of 7.3 × 10−10 M, corresponding to 0.75 μg L−1. It showed linear responses in the range of 7.7 × 10−10 to 1.9 × 10−9 M of MC-LR (corresponding to 0.77–2.00 μg L−1), thus including the limiting value for MC-LR in waters (1.0 μg L−1). The potentiometric-selectivity coefficients were assessed by the matched potential method for ionic species regularly found in waters up to their limiting levels. Chloride (Cl) showed limited interference while aluminium (Al3+), ammonium (NH4+), magnesium (Mg2+), manganese (Mn2+), sodium (Na+), and sulfate (SO42−) were unable to cause the required potential change. Spiked solutions were tested with the proposed sensor. The relative errors and standard deviation obtained confirmed the accuracy and precision of the method. It also offered the advantages of low cost, portability, easy operation and suitability for adaptation to flow methods.

Graphical abstract: Determination of Microcystin-LR in waters in the subnanomolar range by sol–gel imprinted polymers on solid contact electrodes

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Article information


Submitted
31 Jan 2012
Accepted
23 Feb 2012
First published
22 Mar 2012

Analyst, 2012,137, 2437-2444
Article type
Paper

Determination of Microcystin-LR in waters in the subnanomolar range by sol–gel imprinted polymers on solid contact electrodes

R. B. Queirós, J. P. Noronha, P. V. S. Marques, J. S. Fernandes and M. G. F. Sales, Analyst, 2012, 137, 2437
DOI: 10.1039/C2AN35141B

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