CURRENT CHARACTERIZATION TOOLS FOR ENM FOR FOOD APPLICATION
When analysing ENMs in food matrices, obtaining representative samples can be a very
difficult task.
When the ENM is inc...
WHY IS THIS PROBLEM SO DIFFICULT TO ANALYZE?
SOLUTION
ELECTRON MICROSCOPE (SEM , TEM)
 It is a microscopy technique that produces images of a sample with a
focused beam of ele...
A SAMPLE VIEWED BY SEM, AFM AND TEM:
Zno dispersed in distilled water, allowed to dry. Obtained size- 50-70nm.
DYNAMIC LIGHT SCATTERING
 A technique used to determine the size distribution of
small particles in suspension or polymer...
INDUCTIVELY COUPLED PLASMA MASS SPECTROMETER (ICP-MS)
 A type of mass spectrometer capable of detecting metals and
severa...
SURFACE PLASMON RESONANCE ASSAYS
 It is a physical surface phenomenon whereby collective
oscillations of electrons on a m...
THANK YOU
of 10

Nanomaterials in food

Characterization techniques in food.
Published on: Mar 3, 2016
Published in: Food      
Source: www.slideshare.net


Transcripts - Nanomaterials in food

  • 1. CURRENT CHARACTERIZATION TOOLS FOR ENM FOR FOOD APPLICATION
  • 2. When analysing ENMs in food matrices, obtaining representative samples can be a very difficult task. When the ENM is incorporated into the food matrix, changes in pH, ionic strength, ionic composition, cooling or heating as well as mechanical stress during food production and digestion can lead to the alteration of the ENM. Food constituents can interact with nanoparticles and alter their properties. So, techniques should be sensitive enough to measure low concentrations INTRODUCTION
  • 3. WHY IS THIS PROBLEM SO DIFFICULT TO ANALYZE?
  • 4. SOLUTION
  • 5. ELECTRON MICROSCOPE (SEM , TEM)  It is a microscopy technique that produces images of a sample with a focused beam of electrons.  The electrons interact with atoms in the sample, producing signals that can be detected  Gives information about the sample's surface topography and composition which includes information about the state of aggregation, dispersion, sorption, size , structure and shape.  Materials to be viewed under an electron microscope need sample preparation.  Electron microscopy can achieve resolution better than 1 nanometer. Scanning electron microscope
  • 6. A SAMPLE VIEWED BY SEM, AFM AND TEM: Zno dispersed in distilled water, allowed to dry. Obtained size- 50-70nm.
  • 7. DYNAMIC LIGHT SCATTERING  A technique used to determine the size distribution of small particles in suspension or polymers in solution.  Rayleigh scattering phenomenon is observed in the process.  Due to laser, the scattering intensity fluctuates over time. This fluctuation is due to Brownian motion, so the distance between the scatterers in the solution constantly changes with time.  This scattered light then undergoes either constructive or destructive interference by the surrounding particles.  Interferences can be caused by dust particles can have a great influence on the scattering intensity and therefore on the sizing result Schematic of DLS
  • 8. INDUCTIVELY COUPLED PLASMA MASS SPECTROMETER (ICP-MS)  A type of mass spectrometer capable of detecting metals and several non- metals at concentrations as low as one part in 1012 (part per trillion)  Achieved by ionizing the sample with inductively coupled plasma and then using a mass spectrometer to separate and quantify those ions  Example: TiO2 levels in food can be determined by purchasing white-colored foods and personal care products. Food samples first to milder digestion with hydrogen peroxide and nitric acid only, then passing through nylon filters with a pore size of 450 nm and then analyzed .  This shows that a significant fraction (about 36%) of the TiO2 particles deliberately added to the tested foods were of nanoscale size. Schematic of Spectrometer
  • 9. SURFACE PLASMON RESONANCE ASSAYS  It is a physical surface phenomenon whereby collective oscillations of electrons on a material’s surface (called plasmons) come into resonance with the natural oscillation of incoming photons.  SPR has been used in the development of biosensors that can directly monitor the interaction between an analyte and ligand present on a sensor chip.  For example: Use of a human-metallothionein-based SPR sensor chip to detect and measure AgNPs in food and environmental samples. The hypothesis was that if AgNPs are present in the test matrix, they will bind to the protein and induce a change in the SPR response of the gold chip surface.  It was observed that the sensitivity of the sensor increased as the size of the AgNPs increased, due to the enhancement of the SPR signal, which is proportional to the mass of the binding analyte. Change in mass concentration at the sensor surface alters the refractive index and angle at which an SPR signal is generated.
  • 10. THANK YOU

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