Determination of trace mercury by solid substrate room temperature phosphorescence quenching method based on lead carboxymethyl cellulose (Pb(CMC)2) particles containing luminescent salicyl fluorones molecules

Luminescent particles of lead carboxymethyl cellulose (Pb(CMC)2), which contains salicyl fluorones (THBF), Pb(CMC)2-THBF, were synthesized by sol-gel method. Pb(CMC)2-THBF can emit intense and stable solid substrate room temperature phosphorescence (SS-RTP) on filter paper. EDTA can chelate the Pb2+ in Pb(CMC)2-THBF, causing it decompose into aqueous soluble components PbY2−, CMC− and THBF, and these components can react with Hg2+ to form (CMC)2Hg-THBF, causing decrease of phosphorescence intensity. Based on the facts above, a new method for the determination of trace mercury by SS-RTP quenching method was established. The linear range of this method is 2.0-40.0 fg spot−1 (5.0-100.0 pg ml−1) of Hg2+, with a detection limit (LD) of 0.26 fg spot−1, and the regression equation of working curve is ΔIp=13.02+1.165mHg2+ (fg spot−1, 0.4 μl spot−1), r = 0.9994. This method has been applied to the determination of trace mercury in water sample with satisfactory results. The mechanism of SS-RTP emission is also discussed.