Water-soluble CdTe quantum dots (QDs) and their conjugates with antibodies and antigenes were prepared by optimized procedures for applications in CE immunoassays. The QD size of 3.5 nm, excitation spectrum in the range of 300-500 nm, the maximum wavelength of the emission spectrum at 610 nm, quantum yield of 0.25 and luminescence lifetimes in the range of 3.6-43 ns were determined. The 0.1M solution of TRIS/TAPS (pH 8.3) was found to be the optimum buffer for the separation of the anti-ovalbumin-ovalbumin immunocomplex from the free conjugates of QDs.