Sirius Insight

An innovative particle size analyser which makes particle size measurements easier, more meaningful and robust.

Sirius Insight - Particle Size and Shape Analyser

Size Matters

Particle size is a key physical property for many materials which has an important impact on product and process performance. For pharmaceuticals, the particle size of the active pharmaceutical ingredient and excipients can affect bioavailability, stability and the ability to process and manufacture a product. Particle size is often a critical quality attribute controlled by a compound specification.

The measurement of particle size can be a significant analytical challenge during drug development to ensure that results are meaningful and enable the effective control of product and process. The analytical approach taken must ensure suitable dispersion of the sample and utilise an effective measurement technique to deliver an accurate and reproducible particle size distribution.

Sirius Insight

The new Sirius Insight is an innovative particle size analyser which makes particle size measurements easier, more meaningful and robust. The instrument utilises two measurement methods: Laser Obscuration Time (LOT) and digital video imaging. This dual channel approach enables the measurement of particle size using the LOT technique and provides a large number of particle shape parameters through dynamic image analysis. The LOT method possesses many advantages as a sizing technique:

  • LOT is independent of optical properties and makes no assumptions about the particles being measured (e.g. shape or refractive index). This makes it very suitable for making accurate size measurements on samples which are either single compounds or mixtures of compounds such as drug-excipient blends.
  • It is not a volume based measurement, so it can be used effectively for polydispersed samples or samples and samples with minor size fractions.
  • LOT is a time-domain measurement, making it suitable for solids concentration measurements.
  • Dual channel detection gives high information content: the video channel enables the determination of a number of particle shape parameters. This powerful feature enables material behaviour to be correlated with particle properties other than size.


Sirius Insight - Particle Size and Shape Analyser


Effective sample dispersion is critical to making valid particle size measurements. Sirius Insight offers a modular design with nine different dispersion cells to optimise the dispersion process for your sample. These include: small volume stirred cells, a flow through cell, a slide cell (which enables the determination of particle size of suspended solids in ointments for example), and a heated cell. These are easily interchangeable. It’s an application driven approach that accommodates particles in liquids, emulsions, dry powders, fibres, heated liquids and aerosols.

PS distribution: LOT measurement provides high resolution particle size distributions which can be presented as number or volume distributions.


Particle Size using Laser Obscuration Time

The laser channel determines particle size by analysing the interaction of the laser beam with the particles in the measurement zone. The laser is focussed into a narrow spot which is rotated by a wedge prism so that the beam describes a narrow circular path in the sample zone. When the laser beam interacts with a particle in its path, a photo diode detects the duration of the temporary interruption of the laser beam by the particle. The time of obscuration is directly related to the chord length of the particle that interacted with the laser beam; larger particles give longer obscuration duration than smaller particles. The results can be presented in volume and number size distributions. This technology gives access to the direct measurement of particle size; it is not inferred from another property which requires a mathematical model to derive particle size.

LOT measurement principle: The LOT measurement is mounted on an optical bench which accommodates a number of different dispersion systems. 

LOT measurement principle: This principle enables the laser beam to interact with a very large number of particles. Accurate particle size measurements are assured by peak profile analysis to ensure that only on-centre and in-focus interactions are recorded. 

Particle Imaging using Dynamic Image Analysis
The addition of a second measurement channel enables a wealth of particle shape data to be acquired through digital video microscopy. Images can be acquired on the same particle population measured by the laser channel. These are processed to provide up to 40 shape parameters. Detailed object information is available for all particles detected. Image analysis is particularly valuable for determining the size of non-spherical particles and gives the opportunity to understand how particle properties impact the performance of the product and the process.

Digital Image Analysis: The video analysis channel collects digital images used for visualisation during laser measurements, capturing images, recording movies and dynamic shape analysis. 


Sirius Insight makes the best use of your laboratory space. With a small footprint of 665(w) x 280(d) x 183(h) it can be easily accommodated in most laboratories


You are not on your own. When you purchase Sirius Insight you will have access to Sirius’ expert applications chemist and engineering support.

Try It

There are many techniques available for particle size analysis but you will find that the LOT sizing technique will give you a different insight into your particles.

Features and Benefits



Two independent measurement channels  (LOT and Image Analysis). Assesses number of particles, size and shape in the same sample.

This is the instrument to use if you really want to understand particle size and shape.

Laser Obscuration Time (LOT) measures particle diameter as a chord length of a particle as it obscures the laser beam. Gives particle diameter by number from first principle but is also capable of generating particle size distributions as a function of volume, surface area and length.

Good for irregularly-shaped particles; don’t need to know the refractive index or absorbance of the sample or the dispersion medium.  Does not need to make assumptions about shape in the measurement.

Image analysis assesses the shape of particles.

Capable of analysing a large variety of shape parameters which can be used to differentiate between samples which may otherwise appear very similar using more traditional particle size analysis methods.

In-situ visualisation shows live images of suspended particles while size is being measured.

Useful for ensuring particles are adequately dispersed in the medium.  A handy tool for interpreting data and understanding anomalies such as agglomerates and flocculation.

User-friendly software has many useful features.

Quick to learn and easy to use.

Saves all data collected during each measurement which can be referred back to at any time. Can collect and compare 30 different size and shape parameters. Many options for visualisation graphs and histograms.

A good tool for particle size research.

Accommodates various sample types: water-based, oil-based, powder-based

Versatile instrument which can accommodate many different of dispersion systems.

Option to use disposable cuvettes

Reduces the need for cleaning and wash-cycles which can save time.

Small size, weight and footprint

Compact design fits easily on laboratory bench.