Precipitation of αl-glutamic acid: determination of growth kinetics

Abstract

Growth kinetics of alpha L-glutamic acid was determined based on seeded batch desupersaturation experiments. The growth rate correlation applied in this study accurately describes the growth process in a temperature range of 25-45 degrees C and in a supersaturation range of 1-3. The newly developed approach for the growth rate characterization has the advantage of a high robustness especially with respect to the influence of competing particle formation mechanisms as nucleation or agglomeration. The efficient technique employs in situ process analytical technologies, e.g. attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and focused beam reflectance measurement (FBRM), different ex situ analytical tools and population balance modeling combined with a non-linear least squares optimization algorithm to determine the growth kinetics. The growth mechanism was identified to be integration controlled and of birth and spread (B + S) type. The quality of the determined growth rate correlation was assessed by comparison with the experimental data and with literature data.

Effect of temperature on the nucleation kinetics of α l-glutamic acid

“…(16) is valid for 3D growth of spheres, when the growth kinetics is controlled by surface integration [7]. The last assumption about the growth controlling mechanism is consistent with a previous work, where it was shown to be based on the ''birth and spread'' mechanism, as given by [23] G …”

“…(17)) to diffusioncontrolled growth [4]. However, it was shown that the measured growth rates of L-glutamic acid are at least one order of magnitude smaller than predicted diffusion-controlled growth rates [23].…”

“…ATR-FTIR is used to determine the starting time of the precipitation process, namely when mixing is completed and the initial supersaturation is established. To determine this point, the band in the IR spectra at 1408 cm À1 , which corresponds to the dissociated carboxylic groups in the L-glutamic acid molecule [23], is used. Phase 1 in Fig.…”

Precision measurement of the growth rate and mechanism of ibuprofen {001} and {011} as a function of crystallization environment

“…Nowadays, in-process data mostly uses FBRM instrumentation [19][20][21] which measures only the chord length distribution which can be challenging to extract 'first-principles' face-specific kinetics [45].…”

“…using focused beam reflectance measurements (FBRM) [19][20][21], rather than face-specific growth rates as measured for batches of individual crystals. For example, most of commercial particle size instruments calculate the crystal 'size' in terms of a volume equivalent diameter (D volume ) where:…”