An Ultrasensitive Detection Platform for Mercury Ions Speciation in Water Using Procaine Hydrochloride Ion Pair Coupled Extractive Spectrofluorimetry.

A simple extractive spectrofluorimetric strategy for trace determination of mercury(II) ions in water employing procaine hydrochloride (PQ+ ) as an ion pairing fluorescent tagging reagent has been established. The method was based upon the extraction of PQ+ from aqueous iodide media onto dichloromethane as a ternary complex ion associate [(PQ+ )2 .(HgI4 )2- ] at pH 9.0-10.0 with subsequent quenching at λex/em  = 268/333 nm. The developed strategy exhibited a linear range 20-140 nM with a lower limit of detection (LOD) 6.1 nM, respectively. Intra and inter-day laboratory accuracy and precision for trace analysis of mercury(II) ions in water were performed. Complexed mercury(II) species in real water samples were evaluated along with chemical speciation and successful comparison with most of the reported methods. The method was validated by standard inductively coupled plasma-optical emission spectrometry (ICP-OES) method in terms of student's t- and F tests at 95% confidence interval. The method offers rapidity, selectivity, cost-effectiveness, robustness, and ruggedness. Graphical Abstract Schematic illustration of the proposed sensing mechanism for mercury(II).