Analytical chemistry 2012-10-16

Determination of ammonia in water based on chemiluminescence resonance energy transfer between peroxymonocarbonate and branched NaYF4:Yb3+/Er3+ nanoparticles.

Hui Chen, Haifang Li, Jin-Ming Lin

Index: Anal. Chem. 84(20) , 8871-9, (2012)

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Abstract

The ultraweak chemiluminescence (CL) from the reaction of hydrogen peroxide and carbonate is strongly enhanced by the branched NaYF(4):Yb(3+)/Er(3+) nanoparticle (NP) in the presence of aqueous ammonia. It was explained that ammonia catalyzes the decomposition of peroxymonocarbonate, which is the product of hydrogen peroxide mixing with bicarbonate, making the formation of (CO(2))(2)*, (O(2))(2)*, and (1)O(2). The excitation energy, carried by these emitter intermediates, can be transferred to NaYF(4):Yb(3+)/Er(3+) NP. The CL intensity is directly proportional to the concentration of ammonia present in the solution. A flow-injection CL system with high sensitivity, selectivity, and reproducibility is proposed for the determination of aqueous ammonia. The proposed method exhibited advantages in a larger linear range from 0.5 μmol L(-1) to 50 μmol L(-1) and a lower detection limit of 1.1 × 10(-8) mol L(-1) (S/N = 3). This method has been successfully applied to the evaluation of ammonia in water samples with recoveries from 95% to 108%. The relative standard deviations are 1.8% and 4.1% for intra-assay and inter-assay precision, respectively.