Real-Time Measurement of the Growth Rates of Individual Crystal Facets Using Imaging and Image Analysis

Measurement, modelling, and closed-loop control of crystal shape distribution: Literature review and future perspectives

“…Calderon de Anda et al [19] have investigated the use of the GlaxoSmithKline's imaging system for monitoring the crystallisation on-set and dynamic transition from one polymorph to another during crystallisation of LGA crystals. A multi-scale image analysis method [26,59] was developed and used to derive monitoring charts [17], and then to calculate the real-time growth rates associated with the evolution of the length and width for the needle-like -polymorphic form of LGA [60].…”

“…Some studies were carried out with success in literature [19,60] to obtain facet growth kinetics using on-line imaging for real-time characterisation of particle shape. A feasibility study was conducted to estimate the growth rates of needle-shaped -form LGA crystals in two dimensions in a crystalliser under a cooling rate of 0.1 o C/min [60].…”

“…A feasibility study was conducted to estimate the growth rates of needle-shaped -form LGA crystals in two dimensions in a crystalliser under a cooling rate of 0.1 o C/min [60]. Under the experimental operating conditions, the length growth rate was estimated as between 2.44 ×10 −8 and 3.0 × 10 −8 m/s, while the growth rate for the width is between 0.558 × 10 −8 and 0.502 × 10 −8 m/s.…”

“…For growth rate measurement of individual faces in a reactor based on on-line imaging, a time window is used, i.e. using images not only at the current time but also those before the current moment, the window width can be defined by users [60,70]. Although some advances have been made [45,50,64,65,69,73,139,140], further research is definitely needed to address this issue, and also the effect of secondary nucleation, breakage/aggregation, high-solid concentration, and co-existence of multiple polymorphic forms on accurate estimation of facet crystal growth rates.…”

Particle shape characterisation and classification using automated microscopy and shape descriptors in batch manufacture of particulate solids

“…One of the properties for particulate products is shape, not only because it is now recognized that size alone as often defined as volume equivalent diameter is over simplified and sometimes misleading, but also because shape can affect product performance properties such as bioavailability of drug particles. Optical microscopy has been proved to be one of the most effective techniques to determine particle shape and size off-line or on-line (Brittain, 2001; Calderon De Anda, Larsen, Rawlings, & Ferrier, 2006;Larsen, Rawlings, & Ferrier, 2007;Wang, Calderon De Anda, & Roberts, 2007;Wang, Roberts, & Ma, 2007). The images can be analyzed using image analysis algorithms (Zhang & Lu, 2004) to obtain particle shape information, which is often defined by some descriptors that have physical meanings such as aspect ratio.…”