Quenchofluorimetric Determination of Mercury Trace with Murexide

Abstract.

 A sensitive and fairly selective quenchofluorimetric method for the determination of mercury ultra-trace with murexide (ammonium purpurate) has been developed. The method is based on the instantaneous quenching action of the metal-ion upon the native fluorescence of murexide [λ_ex(max) = 360 nm; λ_em(max) = 445 nm] in the optimum pH range of 5.8 to 6.6 at room temperature (25±0.5) °C. The fluorescence quenching is collinear in the range of 5 µg/L to 100 µg/L mercury. The developed method is very precise and accurate (RSD = 2.2% for 11 determination of 50 µg/L Hg(II). Large excesses of more than 50 cations, anions and complexing agents were found to have no interference. The developed method was successfully tested over synthetic mixtures of various compositions, certified reference materials and factory effluents.