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