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Determination of Ethion Using Silver Nanoparticles as Probe by Resonance Rayleigh Scattering (CAT#: STEM-ST-0020-YJL)

Introduction

Pesticides and insecticides are used to protect agricultural crop against damaging caused by insects. However, ecological compartments such as lakes and rivers may be contaminated by these chemicals through rains and wind, affecting many other organisms far from the first target. Organothiophosphates (OTPs) with a thiophosphoryl (P=S) functional group constitute a broad class of widely used organophosphates (OPs) insecticides. Organophosphates insecticides include very lethal nerve agents and chemical warfare agents, such as, VX, Soman, and Sarin. OTP compounds are used frequently in agricultural lands worldwide and has resulted highly toxic residuals in crops, livestock, and poultry products which has further led to their migration into underground aquifers.




Principle

Resonance Rayleigh scattering (RRS) is similar to Rayleigh scattering in nature. Resonance Rayleigh scattering is a special elastic scattering produced when the wavelength of Rayleigh scattering (RS) is located at or close to its molecular absorption band. The key to generating RRS is: when the scattering is at or close to the absorption band of the scattering molecule, since the electron absorbs the electromagnetic wave at the same frequency as the scattering frequency, the electron strongly absorbs the photon energy due to resonance and re-scatters. Its scattering intensity is several orders of magnitude higher than that of pure Rayleigh scattering, and it no longer obeys the Rayleigh law of I∝λ-4. This absorption-rescattering process is called resonance Rayleigh scattering (RRS).

Applications

Resonance Rayleigh scattering is used to the study of aggregation of chromophores on biological macromolecules and the determination of biological macromolecules such as nucleic acid, proteins and heparin, further, it has been used in the determination of trace amounts of inorganic ions and the cationic surfactant by means of ion association reactions with some dyes. In addition, it has been applied to the study of nanoparticles in liquid and the determination of β-cyclodextrin inclusion constant and the critical micelle concentration of surfactant.

Procedure

1. Sample preparation
2. Measurement by scattering detection instrument
3. Data analysis

Materials

Rayleigh scattering measurement system