Resonance Rayleigh Scattering, Resonance Non-linear Scattering Spectra Of Some Nanoparticles And Their Analytical Applications

Nowadays, an increasing number of scientists are focusing on resonance Rayleigh scattering (RRS) and resonance nonlinear scattering (RNLS) such as SOS and FDS. As new analytical techniques, RRS and RNLS have been widely applied in numerous fields because of their high sensitivity, rapidness and simplicity. In recent years, the studies and determinations of surfactants, inorganic ions, organic compounds, and some biological macromolecules using RRS, FDS and SOS methods have obtained good results. At the same time, some physicochemical parameters such as critical micelle concentration of surfactant,β-cyclodextrin inclusion constant and the critical aggregation concentration of protein and so on have been measured successfully by these methods. In addition, researches in nanoparticles using RRS and RNLS techniques are also increasing. In this paper, we established RRS and RNLS methods for the determination of sodium alginate (SA), potassium ferrocyanide and epinephrine (EP) mainly based on the formation of SA-CTAB, SA-CS, Co₂[Fe(CN)6], Ni₂[Fe(CN)6] and Fe3[Fe(CN)6]2 nanoparticles.The main contents are as follows:1. Analytical application of resonance Rayleigh scattering, frequency doubling scattering and second-order scattering spectra for the SA-CTAB ion-association nanoparticles systemThree new methods for the determination of trace amounts of SA based on the reaction of SA with cetyltrimethylammonium bromide (CTAB) by RRS, FDS and SOS have been investigated. SA can react with CTAB in a pH 10.0 BR buffer to form a new product. The complexes of SA-CTAB with charge neutralization have strong hydrophobicity. They can draw close to each other and further agglomerate to form SA-CTAB nanoparticles under hydrophobic force and Van der Waals force. The formation of nanoparticles can lead to a significant enhancement of RRS, FDS and SOS intensities and appearance of new spectra. The maximum scattering wavelength, λex/λem, is located at 351 nm/351 nm for RRS,240 nm/480 nm for SOS and 870 nm/435 nm for FDS, respectively. Under the optimum conditions, the enhancement of scattering intensities were proportional to the concentration of SA in the range of 0.04-12.5μg mL-1 for RRS, 0.08-12.5μg mL-1 for FDS and 0.08-12.5μg mL-1 for SOS. The detection limit (3a) for SA is 3.69 ng mL-1 for the RRS method,6.91 ng mL-1 for the FDS method and 7.45 ng mL-1 for the SOS method under the optimum experimental conditions. The proposed methods were applied to the determination of SA in real samples with satisfactory results.2. Resonance Rayleigh scattering spectra of SA-CS ion-association nanoparticles and its analytical applicationIn a pH 6.09 BR buffer, SA can react with chitosan (CS) to form SA-CS complexes by virtue of electrostatic attraction. The neutral complexes having strong hydrophobicity can draw close to each other and further aggregate to form SA-CS ion-association nanoparticles. The formation of nanoparticles can result in the enhancement of RRS intensity and their maximum scattering wavelength appears at 341 nm/341 nm. The enhanced RRS intensity is directly proportional to the concentration of SA in the range of 0.1-80.0μg mL-1. In this paper, the RRS spectral characteristics of the SA-CS nanoparticles, the optimum conditions of the reaction and the influencing factors have been investigated. The method exhibits high sensitivity and the detection limits for SA is 48.7 ng mL-1. A novel method for the determination of SA has been developed. The proposed method has been successfully applied to the determination of SA in real samples.3. Determination of potassium ferrocyanide in food by resonance Rayleigh scattering, frequency doubling scattering and second-order scattering methods based on the formation of Co2[Fe(CN)6] nanoparticlesIn BR buffer medium (pH 4.50), Co (â…¡) can react with potassium ferrocyanide to form Co2[Fe(CN)6] complexes. By virtue of hydrophobic force and Van der Waals force, the complexes draw close to each other and further aggregate to form Co2[Fe(CN)6] nanoparticles. The shape and diameter of Co2[Fe(CN)6] nanoparticles have been observed with transmission electron microscopy (TEM), illustrating that the shape of these nanoparticles is cubic and their average size is about 20 nm in the presence of 1.1×10-5mol L-1 potassium ferrocyanide. The formation of Co2[Fe(CN)6] nanoparticles can lead to a significant enhancement of RRS, FDS and SOS intensities and appearance of new spectra. The maximum scattering wavelength,λex/λem, is located at 292 nm/292 nm for RRS,865 nm/432.5 nm for FDS and 240 nm/480 nm for SOS, respectively. The increments of the scattering intensitiesâ–³/(â–³/RRS,â–³/FDS andâ–³/sos) are proportional to the concentrations of potassium ferrocyanide in the range of 0.2-12.0μmol L-1 for RRS,0.2-13.0μmol L-1for FDS and SOS. Those methods have high sensitivities and the detection limits are 2.32×1O-8 mol L-1for the RRS method,2.19×10-8 mol L-1 for the FDS method and 2.66×10-8 mol L-1for the SOS method, respectively. In this paper, the optimum experimental conditions of the system and the influencing factors have been investigated. Moreover, the composition of Co2[Fe(CN)6] complex, the shape and diameter of Co2[Fe(CN)6] nanoparticles were studied. Three sensitive, simple and rapid methods for the determination of trace amounts of potassium ferrocyanide were developed based on the formation of Co2[Fe(CN)6] nanoparticles.4. Study on resonance Rayleigh scattering, frequency doubling scattering and second-order scattering spectra of Ni2[Fe(CN)6] nanoparticles and their analytical applicationsThree novel methods for the determination of trace amounts of potassium ferrocyanide by RRS, FDS and SOS methods have been established based on the formation of Ni2[Fe(CN)6] nanoparticles. In pH 4.00 BR buffer medium, Ni (II) can react with potassium ferrocyanide to form neutral Ni2[Fe(CN)6] complexes, which can further aggregate to form nanoparticles under the extrusion action of water and Van der Waals force. Under the experimental conditions, the shape and diameter of nanoparticles have been observed by TEM, which shows the shapes of these nanoparticles are uniform cubic and their average sizes are about 21±2 nm in the presence of 1.1 x 10-5 mol L-1potassium ferrocyanide. The formation of Ni2[Fe(CN)6] nanoparticles leads to a significant enhancement of RRS, FDS and SOS intensities and appearance of new spectra. The maximum scattering wavelength,λex/λem, appears at 348 nm/348 nm for RRS,240 nm/480 nm for SOS and 860 nm/430 nm for FDS, respectively. In this work, the RRS, FDS and SOS spectra, the optimum conditions of the reaction system, the influencing factors as well as the composition of Ni2[Fe(CN)6] complex were investigated. In addition, the enhancement reasons of RRS, FDS and SOS have been discussed. Three sensitive and simple methods for the determination of trace amounts of potassium ferrocyanide have been developed.5. Determination of epinephrine by resonance Rayleigh scattering, frequency doubling scattering and second-order scattering methods based on the formation of Fe3[Fe(CN)6]2 nanoparticlesThree novel and sensitive methods to determine trace amounts of EP by RRS and RNLS such as FDS and SOS have been established based on the formation of Fe3[Fe(CN)6]2 nanoparticles. In the presence of EP, Fe3+can be reduced to Fe2+at pH 1.9. Fe2+further reacts with [Fe(CN)6]3- to form Fe3[Fe(CN)6]2 complexes which can aggregate to form Fe3[Fe(CN)6]2 nanoparticles by virtue of hydrophobic force and Van der Waals force. Under the experimental conditions, the shape and diameter of Fe3[Fe(CN)6]2 nanoparticles have been observed by TEM, and the results show that the shapes of these nanoparticles are uniform cubic and their average sizes are about 12±2 nm in the presence of 1.0μg mL-'EP. The formation of Fe3[Fe(CN)6]2 nanoparticles not only results in the remarkable enhancement of RRS, FDS and SOS intensities and appearance of new spectra, but also leads to a change of absorption spectra. The increments of the scattering intensitiesâ–³/(â–³/RRS,â–³/FDs andâ–³/SOS) are proportional to the concentrations of EP in a range of 0.02-2.0μg mL-1 for the RRS method,0.04-1.6μg mL-1 for the FDS method and 0.04-1.4μg mL-1 for the SOS method, respectively. Those methods exhibit high sensitivities and the detection limits are 0.87 ng mL-1for the RRS method,1.83 ng mL-1 for the FDS method and 4.70 ng mL-1 for the SOS method, respectively. At the same time, the characteristics of absorption, RRS, FDS and SOS spectra of this reaction, the optimum experimental conditions as well as the influence of some foreign substances have been studied. Moreover, the reaction mechanism has been discussed in this work. These methods have been applied successfully to the determination of EP in injection samples.