SUMMARY

This thesis includes five main chapters:

Chapter one: Contains a general introduction to tea, caffeine, lithium, sodium, potassium, calcium, fluoride, nanotechnology, and nano-sensors. It includes also information about lanthanum nanoparticles, methods used for synthesizing it, especially green synthesis and factors influencing the synthesis of various nanoparticles.

            Chapter two: Involves the literature survey about techniques used for the determination of caffeine, lithium, sodium, potassium, calcium, and green synthesis of lanthanum nanoparticles as well as includes a literature review for the determination of fluoride. In addition, it includes the aim of the research project.

          Chapter three: Includes the experimental part, which consists of the chemical compounds and instrumentations, preparation of samples and standard solutions, preparation of (Zea maize L.) extract, and preparation of lanthanum nanoparticles. It contains also, the construction of electrodes using lanthanum nanoparticles prepared from maize extract.

           Chapter four: consists of three parts; the first part is about extraction and determination and characterization of caffeine in tea samples using two different solvents for comparison between them. The second part is about the determination of lithium, sodium, potassium and calcium in tea samples using flame atomic emission spectroscopy and flame atomic absorption spectroscopy.

The third part was divided into two sub parts the first was about the techniques which were used for the characterization of prepared lanthanum nanoparticles. The maize extract fourier transform infrared spectroscopy shifted when comparing with fourier transform infrared spectroscopy for lanthanum nanoparticles prepared from maize extract, ultraviolet/visible spectroscopy of synthesized lanthanum nanoparticles prepared from maize extract showed absorption maximum at 233.5 nm which is different from that of maize extract which is 286.5 nm. The X-ray diffraction crystallography examination indicates that lanthanum nanoparticles prepared from maize extract was semi-crystalline and its crystalline size was around 4.0 nm, field-emission scanning electron microscopy showed that lanthanum nanoparticles prepared from maize extract appeared to be morphologically spherical, uniform aggregate and agglomerated on the structure of the polymer. The clouded materials indicate the influence of strong composite morphology. Energy disperse X-ray indicated that the nano compound contains lanthanum and fluorine elements which are evidence for the preparation of lanthanum nanoparticles prepared from maize extract.

The second sub part was applications of lanthanum nanoparticles prepared from maize extract, which was the determination of fluoride using commercial fluoride ion selective electrode and prepared lanthanum nanoparticles prepared from maize extract electrode. Fluoride was successfully determined by commercial and lanthanum nanoparticles prepared from maize extract electrodes; the best results were obtained at pH 6. The calibration curve was drawn for solutions of fluoride for both electrodes in the concentration range: (5.0  10^-6 – 4.0  10^-3) mol/L with the regression coefficient of 0.9992 and 0.9978 for commercial and lanthanum nanoparticles prepared from maize extract electrodes, respectively.

The precision of the method was investigated for three different concentrations (5 ^-6, 7.5 10^-5 and 4 10^-3) mol/L the range of RSD% was between (1.9261 – 0.2659) % for commercial electrode and ((-3.0452) – 4.4400)% for lanthanum nanoparticles prepared from maize extract electrode. The accuracy of the determinations as the relative error was also estimated which allows between ((-4.70) – 3.14)% for fluoride.

              Chapter five: contains the recommendation and future works.