Quenchofluorimetric determination of mercury trace with murexide

A sensitive and fairly selective quenchofluorimetric method for the determi nation of mercury ultra-trace with murexide (ammonium purpurate) has been d eveloped. The method is based on the instantaneous quenching action of the metal-ion upon the native fluorescence of murexide [lambda (ex(max)) = 360 nm; lambda (em(max)) = 445 nm] in the optimum pH range of 5.8 to 6.6 at roo m temperature (25+/-0.5)degreesC. The fluorescence quenching is collinear i n the range of 5 mug/L to 100 mug/L mercury. The developed method is very p recise and accurate (RSD = 2.2% for 11 determination of 50 mug/L Hg(II). La rge excesses of more than 50 cations, anions and complexing agents were fou nd to have no interference. The developed method was successfully tested ov er synthetic mixtures of various compositions, certified reference material s and factory effluents.