Method development for synthesis of semiconductor nanoparticules and analytical applications

Methods for the synthesis of semiconductor nanocrystals, especially CdSe and CdTe, in aqueous solution at room temperature using hydride generation set up are proposed. Semiconductor nanocrystals synthesized with the proposed method and also using a method from the literature were characterized by photoluminescence spectroscopy. Semiconductor nanocrystals that had narrow spectral bands in their photoluminescence spectra were further characterized with transmission electron microscopy, scanning electron microscopy and energy dispersive X-ray analysis. Among them, CdTe has the characteristics of quantum dots. Therefore, it was used for the analytical applications and for the synthesis of bifunctional nanocomposits. Magnetic properties and crystal structure of the bifunctional nanocomposit material, CdTe-Fe3O4, was further investigated by measuring the hysteresis loops and X-ray diffraction. The typical characteristics of super paramagnetic (8 emu/g) and fluorescence spectral (75 nm full width at half maximum) behaviors were observed.As analytical applications, CdTe quantum dots were used as a fluorophore for the determination of mercury in water, thiomersal in pharmaceutical preparation, glucose in dextrose serum and urea in serum samples. The linear ranges and limit of detection values were, 4 x 10-7-20 x10-7 M and 0,6 x10-8 M for mercury in water, 8-80 mg/L and 1.5 mg/L for thiomersal in pharmaceutical preparation, 5 x10-4-50 x 10-4 M and 5 x 10-5 M for glucose in dextrose serum, 4- 40 mg/L and 0,54 mg/L. Accuracy of the methods was demonstrated using percent recovery from spiked water samples for mercury determination, labeled values for thiomersal and analytical and a reference method for urea determination. The precision of the sequential measurements in terms of percent relative standard deviations were less than 5%.Key words: Quantum dot, cadmium telluride, mercury, glucose, urea