Physical Characterisation

Physical characterization refers to the process of measuring and analyzing various physical properties of materials. Some common techniques used for physical characterization are:

Thermal Services

X-Ray Diffraction

Particle Size Distribution

Rheology and Viscosity

Texture

Specific Surface Area (SSA, BET) and Density

Powder Flowability

Thermal Services

DSC and TGA can be applied in a broad range of ways to elucidate the number of polymorphs, hydrated forms, melting point, Tg, degradation behaviour, polymorphic conversion, recrystallisation and heat capacity of an API and excipients. DVS is used to study the response of material to changes in humidity, it is essential in understand physico-chemical behaviours such as stability and microbiological activity. Moisture induced phase changes can affect mechanical properties, induce chemical and biophysical interactions which can lead to changes in dose, yield and efficacy. XRD is a complimentary technique (see XRD offering).

Equipment

• TA TGA 5500
• DSC2500
• SDT650 (TGA/DSC combined)
• DVS Advantage

X-Ray Diffraction

The physical form of ingredients used in both food and pharmaceuticals can have a major impact on the desired properties for finished products. X-Ray Powder Diffraction (XRPD) is a powerful technique both on its own and in combination – DSC, TGA etc. XRPD can help to determine which available polymorph is most desired.

Equipment

• Bruker D2 phaser
• Bruker D8 Advance, with temperature and humidity stage.

Particle Size Distribution

Particle size distribution (PSD) is a fundamental measurement in the product life cycle. The link between particle size and product performance are known to affect dissolution rate, absorption rates and content uniformity. The processability and stability of a formulation are all dependent on PSD.

During formulation of a product the flow and packing properties, tablet and capsule fill volumes, compression, dissolution and blend uniformity can all be affected by PSD. At RSSL we have a series of instruments that allow the measurement of PSD and particle shape/morphology. We are also highly experienced in method development and validation.

Equipment

• Malvern Mastersizer 2000 and Mastersizer 3000
• Zetasizer ZSP (Zetapotential and DLS)
• Sieving
• Lumisizer (emulsion stability) (Analytical centrifuge to monitor accelerated stability of multi-phase samples.)

Rheology and Viscosity

Determines how materials flow and deform under the influence of applied forces or stresses. These techniques are used in various industries, including manufacturing, pharmaceuticals, food and beverages, and research, to understand the flow behaviour of materials and optimise processes accordingly.

The choice of technique depends on the nature of the material being studied, its viscosity range, and the level of precision required. Emulsion or suspension formulations including ointments, lotions and gels often need specific flow properties to enable them to remain stable, be dispensed appropriately, placed into suitable containers and applied correctly, whereas semisolid pharmaceuticals are intrinsically difficult to characterise rheologically as they combine liquid and solid properties within one system. Even simple fluids can affect processes such as heat and mass transfer and the rate of dissolution of a dosage form.

Equipment

• Brookfield LV
• Brookfield RV
• U-tube viscometry
• TA DHR-1

Texture

Texture analysis is a scientific method used to quantify and characterise the physical properties of materials in terms of their tactile and structural attributes. This technique is commonly applied to a wide range of products, including food, cosmetics, pharmaceuticals, and various materials, to understand how they feel and behave under mechanical stress. Texture analysis helps manufacturers ensure consistent product quality and optimise formulations. 

Equipment

• TA.XT Analysers

Specific surface area (SSA, BET) and Density

SSA and Density are two important physical properties that provide valuable information about materials' characteristics and behaviours. They are often used in various scientific, industrial, and research applications to understand materials better and optimise their use. SSA is dependent on the size of the particles, as well as on the structure and porosity of a material, these features are important for characterisation such as during screening for API’s and formulations. 

Equipment

• TriStar II 3020
• Tapped Density
• Bulk density
• Gas Pycnometry
• Oscillating U-tube

Powder Flowability

Powder flowability refers to the ease with which a bulk powder material flows or moves when subjected to external forces such as gravity. It is a critical property in various industries, including pharmaceuticals, food processing, chemicals, and manufacturing, where powders are handled, transported, and processed in various ways. Poor powder flowability can lead to issues such as clogging, inconsistent dosing, and inefficient processing. 

Equipment

• Brookfield Powder Flow
• FT4 Powder rheometer