श्री चित्रा तिरुनाल आयुर्विज्ञान और प्रौद्योगिकी संस्थान, त्रिवेंद्रम
Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum
Central Analytical Facility (CAF) functions as the nodal center for analyzing physico-chemical properties of materials and devices. CAF hosts an array of state of the art equipment for performing a diverse range of analyses including spectroscopy, thermal, chromatography, mechanical and imaging. The facility is open to personnel from industries and academic institutions to get their analysis done on a payment basis. Besides testing, CAF organizes technical sessions for the benefit of students, researchers and teachers. CAF staff is happy to provide technical advice and guidance to customers on their analytical needs.
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UV-Vis spectrophotometry is one of the most frequently used structural characterization techniques based on Beer-Lambert’s law. It works on the principle that compounds containing π-electrons or non-bonding electrons (n-electrons) can absorb the energy in the form of ultraviolet or visible light to excite these electrons to higher anti-bonding molecular orbitals. The wavelength of maximum absorption is inversely proportional to the energy gap between the HOMO and the LUMO of molecules. UV-Vis spectrophotometer can be used for the qualitative analysis (simple read and spectrum scan) as well as quantitative determination of UV/Vis active analytes such as organic compounds, biological macromolecules and surface plasmon resonance (SPR) of active nanomaterials.
Spectrofluorometry is another important structural characterization technique. When compounds containing π-electrons or non-bonding electrons (n-electrons) are excited with radiation with wavelength corresponding to their absorption maximum, these electrons will migrate to high energy anti-bonding molecular orbitals. Excited state is highly unstable and hence the electrons will return to the ground state by emitting absorbed energy in the form of radiation. Spectrofluorometer measures the emitted radiation from an excited molecule and provide information about the chemical structure of the compound. It can be used for the qualitative analysis (simple read and spectrum scan) and quantitative estimation of emissive materials in solution form.
Infrared spectroscopy (IR spectroscopy or vibrational spectroscopy) involves the interaction of IR radiation with matter. When a material is subjected to IR radiation, the chemical bonds in it having definite dipole moment (IR active), start vibrating and each vibration will give rise to characteristic peaks. FTIR spectrum will give information about the functional groups present in the materials. Fingerprint region of FTIR spectrum can be used for the identification of materials and also to check the purity of materials. It can be used as a tool for structure elucidation and to monitor the course of chemical reactions. Samples in the form of solid powders, films and liquids can be analyzed.
High-performance liquid chromatography (HPLC) is an efficient technique to separate, identify, and quantify the components in a mixture. It relies on pumps to pass a pressurized liquid solvent (mobile phase) containing the sample mixture through a column filled with a solid adsorbent material (stationary phase). Each component in the sample interacts slightly differently with the adsorbent material, causing different flow rates for the different components and leading to the separation of the components as they flow out the column. Gel permeation chromatographic (GPC) analysis is done by the size exclusion separation of polymeric molecules when pumped through a Styragel column packed with beads composed of polystyrene cross linked with divinylbenzene. The equipment can be used for the qualitative purity assay and quantitative estimation of components from mixtures. GPC technique can be used for the estimation of molecular weight of polymers relative to standard polymers.
Liquid chromatograph–mass spectrometer (LC-MS) is a sensitive instrument that combines the physical separation capabilities of liquid chromatography (or HPLC) with the mass analysis capabilities of mass spectrometry (MS). While liquid chromatography separates mixtures with multiple components, mass spectrometry provides structural identity of the individual components with high molecular specificity and detection sensitivity. This tandem technique can be used to analyze biochemical, organic, and inorganic compounds commonly found in complex samples of environmental and biological origin. LC-MS technique has been employed in a wide range of sectors including biotechnology, environment monitoring, food processing, pharmaceutical, agrochemical, and cosmetic industries. It can also be used for the mass scan of samples to identify the presence of a compound or to monitor the course of a chemical reaction. Other applications include trace level quantitative estimation of analytes either in selected ion recording (SIR) or Multiple Reactions Monitoring (MRM) modes. Drug metabolite analysis and pharmacokinetics studies can be performed with LC-MS/MS.
Gas chromatography (GC) is used for the analysis of compounds that can be vaporized without decomposition. Typical uses of GC include testing the purity of volatile substances like organic solvents, separating the different components of a mixture (the relative amounts of such components can also be determined) and to quantify volatile residues from materials or devices. In gas chromatography, the gaseous compounds being analyzed interact with the walls of the column, which is coated with a stationary phase. This causes each compound to elute at a different time, known as the retention time of the compound. On comparing the retention time and peak area under specific conditions, compounds can be identified and quantified. Headspace GC analysis is used to analyze highly reactive/toxic vapors such as pesticides, Ethylene Oxide (EtO), etc.
Differential scanning calorimetry, or DSC, is a thermo analytical technique in which the difference in the amount of heat required to increase the temperature of a sample is measured as a function of temperature in comparison with a reference material maintained at identical temperature. The instrument can be used for the determination of heat flow associated with phase transitions or reactions such as melting, crystallization, glass transition, curing, sorption, etc. Thermodynamic properties like enthalpy change associated with specific phase transitions and heat capacity of the materials can be analyzed. Modulated Differential Scanning Calorimetry (MDSC) can be used for the determination of weak thermotropic changes like liquid crystalline phase transitions.
Thermogravimetric analysis determines the weight gain or loss of a condensed phase due to gas release or absorption as a function of temperature. In differential thermal analysis, the temperature difference between a reactive sample and a non-reactive reference is determined as a function of time, providing useful information about the temperatures, thermodynamics and kinetics of reactions. In combined DTA-TGA system both thermal and mass change effects are measured concurrently on the same sample (DTA, TG, DTG). It can be used to measure both weight changes & enthalpy changes associated with transitions and reactions in a material as a function of temperature (or time) under a controlled atmosphere. With this equipment thermal stability of the materials and their compositional analysis can be evaluated. It is capable to differentiate endothermic and exothermic events, which are not associated weight change (e.g. melting and curing) from those which involve weight changes (e.g. degradation).
Texture analyzer is used for the mechanical testing of tissues, food, cosmetics, pharmaceuticals, adhesives and other consumer products either in compression or in tension mode. Texture Analyzers assess textural properties by capturing force, distance and time data at a rate of nearly 500 points per second. Samples are either placed on the base of the texture analyzer or held between two suitable fixtures. In a simple test, the arm of the texture analyzer containing a load cell moves down to penetrate or compress the product, and then returns to its initial position. It can be used for mechanical testing of films/tissues (Compression and tension), fracturability, mucoadhesiveness, gel strength, peel strength, burst strength, consistency measurements of emulsions, creams and gels, adhesiveness of patches, conformability of primary wound dressings, etc.
The Raman Effect is based on the scattering of light when interacted with the chemical bonds of a compound. Due to vibrations of chemical bonds the interaction with photons causes specific energy shifts in the back scattered light that appear in a Raman spectrum. The Raman spectrum is unique for each chemical composition and can provide qualitative and quantitative information of the material. Confocal Raman microscopy is a high-resolution imaging technique that is widely used for the characterization of materials and specimens in terms of their chemical composition without any labeling. The equipment can be used for obtaining the following information: Determination of chemical structure of molecules by Micro Raman Spectroscopy, Confocal Raman Spectroscopic imaging (hyper spectral image generation with information of complete Raman Spectrum at pixel level), Chemical mapping of distribution of components in a mixture by Raman imaging, and Depth profiling, e.g., drug in excipients/tablets, drug eluting stent coatings, live cell imaging, etc.
By using wide variety of light sources and optical filters fluorescence and luminescence of the samples especially biological samples can be quantified and imaged. It is equipped with multipurpose CCD camera system for sensitive and quantitative imaging of membranes, gels, colony counting, etc.
The RVA is a viscometer with ramped temperature and variable shear capability optimized for testing the viscous properties of different types of samples. However, it is important to highlight its versatility due to its capability of analyzing the viscosity in heating-cooling cycles. It can be used for the determination of solution viscosity of biopolymers and viscous properties of starch, alginate, chitosan, hydrocolloids, proteins, etc.
KSV Sigma 701 Force tensiometer is used for the surface property analysis of liquids and solids. As the measurements carried out by force measurements, the dynamic changes of the surface properties can be analyzed accurately by this equipment. Its high sensitivity enables the accurate estimation of surface and interface properties. It can also be used for the determination of Critical Micelle Concentration (CMC) of ambhiphilic materials, Dynamic contact angle of the materials, Powder wettability and surface free energy calculations.
Instron 3345 Universal testing machine is used for the mechanical property measurements of polymeric/rubber specimens in accordance with ASTM standards. The accessory, BioPuls temperature controlled bath, enables the system to perform the mechanical testing both at ambient and simulated physiological conditions.