An optical sensor for mercuric ion based on immobilization of Rhodamine B derivative in PVC membrane

A novel prepared mercuric ion PVC membrane sensor based on a Rhodamine B derivative (RND) as a selective sensing material was described. The sensor exhibited a specific fluorescent off-on response to Hg2+, and showed a linear response over the Hg2+ concentration range from 1.0 × 10−9 to 2.0 × 10−3 M with a very low detection limit of 8.1 × 10−10 M in bulk method. The sensor has also been incorporated into a flow-cell for determination of Hg2+ in flowing streams with improved sensitivity and detection limit. The sensor shows excellent selectivity toward Hg2+ with respect to common coexisting cations. The proposed fluorescence optode was successfully applied to detect Hg2+ in environmental water samples and fish.

► A reversible RND-based mercuric ions PVC membrane sensor was described.
► The unique dual chromo- and fluorescence enhancement was observed.
► The optode has a wide dynamic range, high reproducibility, good selectivity.
► The LODs are 8.1 × 10−10 M and 8.3 × 10−11 M in bulk and flow-cell methods.
► It is useful for routine analysis and the analysis in situ without prior treatment.