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Home > Platforms > Plateforme CPC (Caractérisation Physico-Chimique)

Physico-chemical characterization platform

by Oral Ozlem - 28 November 2023 (modifié le 14 December 2023)

The characterization platform created in 2017 at ISMO became in 2020 a physico-chemical characterization platform which brings together several commercial devices specific to the physico-chemical analysis of solutions and/or surfaces (liquid/solid samples) to respond to the growing needs of research teams.
This platform brings together several equipments for characterizing surface properties, textural analysis and thermal analysis.

CPC platform managers : Ms. Farah Savina and Ms. Ozlem Oral

Thermal analysis
  • TGA : Thermogravimetric analysis
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TGA 4000 from Perkin Elmer

The TGA 4000 from Perkin Elmer makes it possible to study the chemical decomposition of the analyzed sample by applying a temperature ramp (maximum temperature 1000°C)

The principle of the technique consists of measuring the variation of the mass of the sample as a function of temperature (from 30°C to 800°C) or a temperature ramp fixed in a given atmosphere.

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TGA curve of beta_cyclodextrin powder

The measurement atmosphere can be neutral with analysis under inert (nitrogen) or oxidizing (oxygen) gas. Thus, we can evaluate the thermal stability of the analyzed sample and the fraction of volatile components by this mass variation.
This thermal analysis technique applies to any type of sample (solid maximum mass 1500 mg, liquid maximum volume 180 µL). Thermogravimetric analysis brings together the study of different fields of application. Non-exhaustively, we can cite the study of the volatility of the sample, the humidity content, the stability to oxidation, to determine the decomposition temperatures etc.
In Figure 2 we can see the decomposition of β-cyclodextrin as a function of temperature.

  • ITC : Isothermal Titration Calorimetry
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Calorimetric titration apparatus

The Malvern MicroCal PEAQ-ITC calorimetric titration device makes it possible to measure with very high sensitivity the variation of heat which takes place during the interaction between molecules.

It is a measurement technique that makes it possible to determine the enthalpy, the change in entropy, the stoichiometry of the interaction, the dissociation constant of the reaction.
It is a measurement technique that allows the quantitative study of a wide variety of biomolecular interactions. It makes it possible to determine all the binding parameters in a single experiment, the binding constants (KD), the stoichiometry (n), the enthalpy (∆H) and the entropy (∆S) of the reaction.

Surface analysis
  • FTIR-ATR : Fourier transform infrared spectrometer equipped with an Attenuated Total Reflection module
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Perkin Elmer Spectrum two Fourier Transform Infrared

The available FTIR-ATR spectrometer is the Perkin Elmer Spectrum Two Fourier Transform Infrared (FTIR) spectrometer with the Attenuated Total Reflectance (ATR) module for materials analysis. This device allows you to obtain the infrared spectrum of samples analyzed in solid or liquid form.

The FTIR-ATR spectroscopy technique is based on the properties of geometric optics and the laws of Descartes and Beer-Lambert. It is a surface analysis technique that examines a sample over a thickness of the order of a micrometer. The homogeneity of the sample to be analyzed is important.

The homogeneity of the sample to be analyzed is important.
A liquid or solid is placed on top of a diamond crystal and exposed to an infrared beam, over a range of wavelengths, here from 12 μm to 28 μm corresponding to the wave number range of 8300 cm-1 to 350 cm-1.
This wave passes through the diamond crystal, forming a progressive wave called “evanescent” at the interface of the crystal and the sample. The evanescent wave passes through and reflects on the sample surface. This reflection is in fact not total, which is why we speak of attenuated total reflection.

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FTIR-ATR spectrum in transmission of ethanol

The FTIR-ATR spectrometer from Perkin Elmer is equipped with a lithium tantalum detector (LiTaO3), a diamond crystal, and potassium bromide (KBr) separators.

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Synoptic beam path

For a given measurement the best spectral resolution is 0.5cm-1.
This surface analysis technique is used to determine the functional groups of a material.

  • UV-visible spectrophotometer
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UV-Visible spectrophotometer

The CARY300 UV-visible spectrophotometer allows quantitative and qualitative measurement of absorbance (or optical density) of a chemical substance in solution or in film.
This device is equipped with two lamps, one with tungsten covering the visible range from 350 nm to 900 nm and the other with deuterium for the ultraviolet range (190 nm to 350 nm). The device operates with dual beam and dual monochromator scanning.

On a laboratory scale, analysis by UV-visible spectroscopy presents different applications such as determining an unknown concentration, monitoring the kinetics of the reaction.

  • Spectrofluorimeter
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Fluorescence spectrophotometer

The CARY Eclipse fluorescence spectrophotometer allows you to analyze the fluorescence of chemical compounds. This technique makes it possible to study fluorescence properties as a function of the concentration of chemical species.
The device works with a xenon flash lamp whose wavelength range is 200 to 900nm for both excitation and emission. lDetection is done using a photomultiplier, the bandwidths for excitation and emission are 1.5/2.5/5/10/20 nm.

  • Goniometer : Contact angle device

The laboratory has the Krüss DSA 30S goniometer which allows measurements of contact angle and surface energy from drops deposited on a surface.
The laboratory goniometer is equipped with an inclination table which allows the separation of the drop to be observed as well as a pico-drop system. The pico-drop system is automated, allowing both important statistics and better reproducibility (on a surface of 1 cm2 there are approximately 100 drops).
The measurement principle is based on optical photographs and image analyzes of the drop of liquid deposited on a given surface.
The physicochemical parameters of an interface between two phases such as wettability, adhesion on solid surfaces are obtained by various measurements, namely, the contact angle, the surface energy (SFE or posed drop method), surface tension (pendant drop method), and adhesion energy (placed drop and pendant drop methods).
It is equipped with a CCD camera allowing the measurement of contact angles ranging from 0 to 180°
with a resolution of 0.1°, surface tensions from 0.01 to 2000 mN/m with a resolution of 0.01 mN/m.

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Goniometer Krüss DSA 30.
Particle size analysis and zeta potential
  • DLS : Dynamic Light Scattering
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DLS apparatus

The dynamic light diffusion device from Cordouan is an easy-to-use device consisting of a mobile probe composed of two laser beams, a sample holder, all arranged on a rail.
The principle of measurement is based on the diffusion of incident monochromatic radiation (red radiation) by the particles constituting the sample to be analyzed.
Three calculation algorithms (Cumulant, Pade-Laplace, SBL) make it possible to determine the hydrodynamic diameter of the particles with information on the size distribution in intensity, number or volume.
The particularity of the measurement and what makes it interesting concerns the fact of being able to carry out the measurements in situ, in a few seconds with three calculation algorithms making the measurement specific to the sample studied and providing consistency to the result to be analyzed.
This device makes it possible to measure concentrated solutions with better resolution and better analysis of particle distributions. It allows measuring very small sizes (1nm to 5µm) with a minimum volume of 50 µL. As an example, we can cite the measurement of the size of colloidal silica, ceramics, proteins, carbon dots, etc.
This is a non-contact, in situ measurement, the sample remains intact with any type of container during the synthesis. As the device is transportable, measurements can be done “live”.

  • Zeta potential measuring device
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Zêta potential measurement apparatus

The zeta potential measuring device from Cordouan makes it possible to characterize the charge of nanoparticles or colloids. The measuring cell includes an electrode that is placed in the bowl containing the sample.

The zeta potential of a particle or nanoparticle in suspension or in solution represents the electrical charge due to the ions surrounding it.
This is the measure of the intensity of electrostatic or electrical repulsion/attraction between particles. It is one of the fundamental parameters known to affect stability. The measurement provides a detailed view of the causes of dispersion, aggregation or flocculation and can be applied to improve the formulation of dispersions, emulsions or suspensions.
The zeta potential represents the electric charge that a particle acquires thanks to the cloud of ions that surround it when it is in suspension or in solution.