| Recently ,near-infrared luminescence from RE complexes has been reported for the application of clinical diagnostics ,fluoroimmunoassay , the organic fluid laser system and the optical fiber materials , on the other hand the near-infrared luminescence has excellent luminescence properties such as free of background , long life and narrow linewidth .These properties provide possibility to determination of Yb3 +, Er3+ and Nd3+ at the same time ,but this analytical method has been fewer reported .Sensitized near-infrared fluorescence from Yb (3)-Calcein complex in solution was studied in this paper. It was found that Calcein from 2:1 complex with Yb(III) in a pH 8.9 buffer solution under a room temperature. The visible fluorescence from Calcein was quenched when complex forms, while the near-infrared fluorescence from Yb (III) was greatly sensitized. Near-infrared fluorescence intensity of Yb(III) is proportional to its concentration in certain condition. Near-infrared fluorescence of Yb (III) was further enhanced while the visible fluorescence from Yb(III)-Calcein was quenched when second ligand, such as tributyl phosphate (TBP), 1,10-Phenanthroline (Phen) and trioctyl phosphine oxide (TOPO), was added. It was also noted that the near-infrared fluorescence from Yb (III) could be enhanced by addition of small amount of Er3+ ions.P-matrix MLR technique was introduced to determine residual acrylamide in polyacrylamide in the other part of this paper. The method based on the widely used ultraviolet photometry method. The advantage of MLR technique in eliminating spectrum overlap made the method to be more accurate and sensitive. The range of determination is 0-1.0 X 10"3mol.1-1. Satisfactory results were obtained for the determination of samples by using this method.
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