Monitoring the recrystallisation of amorphous xylitol using Raman spectroscopy and wide-angle X-ray scattering

Palomäki, Emmi; Ahvenainen, Patrik; Ehlers, Henrik; Svedström, Kirsi; Huotari, Simo; Yliruusi, Jouko

doi:10.1016/j.ijpharm.2016.04.074

Cited by 12 publications

(12 citation statements)

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“…However, experimental (i.e., external) conditions such as thermal history, surface effects, , relative humidity, , defects or cracks, , and the amorphization itself ,− seem to impact the process of recrystallization from an amorphous state. A wide set of experimental methods could be used to this purpose such as thermal analysis, Fourier transform infrared (FTIR) and Raman spectroscopies, temperature-resolved optical microscopy, dielectric relaxation spectroscopy (DRS), X-ray diffraction or wide-angle scattering (WAXS), terahertz spectroscopy, etc. − …”

Section: Introductionmentioning

confidence: 99%

Molecular Mobility of an Amorphous Chiral Pharmaceutical Compound: Impact of Chirality and Chemical Purity

et al. 2017

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A dielectric relaxation spectroscopy (DRS) study was performed to investigate the molecular mobility of amorphous chiral diprophylline (DPL). For this purpose, both racemic DPL and a single enantiomer of DPL were considered. After fast cooling from the melt at very low temperature (-140 °C), progressive heating below and above the glass transition (T ≈ 37 °C) induces two secondary relaxations (γ- and δ-) and primary relaxations (α-) for both enantiomeric compositions. After chemical purification of our samples by means of cooling recrystallization, no γ-process could be detected by DRS. Hence, it was highlighted that the molecular mobility in the glassy state is influenced by the presence of theophylline (TPH), the main impurity in DPL samples. We also proved that the dynamic behavior of a single enantiomer and the racemic mixture of the same purified compound are quasi-identical. This study demonstrates that the relative stability and the molecular mobility of chiral amorphous drugs are strongly sensitive to chemical purity.

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Section: Introductionmentioning

confidence: 99%

Molecular Mobility of an Amorphous Chiral Pharmaceutical Compound: Impact of Chirality and Chemical Purity

et al. 2017

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“…It can be assumed that at these shear rates sample crystallinity is preserved. Diffractograms of pure xylitol supplied by Sigma Aldrich and of sheared samples were 535 compared to each other as well as with available data in the literature [37]. Figure 13 shows the 536 diffraction patterns of the bulk xylitol and the sheared xylitol.…”

Section: Crystalline Structurementioning

confidence: 99%

Triggering and acceleration of xylitol crystallization by seeding and shearing: Rheo-optical and rheological investigation

Delgado

Navarro

Lázaro

et al. 2021

Solar Energy Materials and Solar Cells

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The present study investigates the triggering and acceleration of xylitol crystallization for its use as a short-term TES. The combined effect of seeding and the action of shear on xylitol crystallization at a supercooled temperature has been investigated by direct observations under shear (rheo-optical approach) and by rheometry. The initial seed is an agglomerate of crystals of xylitol. In addition to the more classical erosion and rupture mechanisms leading to the dispersion of crystals, shear has shown to induce the detachment of crystalline dust adhered to the initial seed into the supercooled xylitol. These crystal fragments then serve as sites for secondary nucleation and subsequent crystallization. Rheo-optical observations have allowed the determination of shear conditions to control the size of crystals by dispersion. A second part has been dedicated to the effect of shear on crystallization of xylitol by seeding by means of rheology. The measurements, although not reproducible, clearly show that seeding in presence of shear (for the investigated conditions) is very efficient to trigger and accelerate the crystallization of xylitol. Post-mortem DSC and XRPD analyses of the final crystallized seeded and sheared samples have not shown any effect on the xylitol crystallinity degree.

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“…In the present study, a Raman spectrometer was used to allow measurement through the bottom of the sample holder and throughout the entire sample volume. The measurement depth is described in more detail in Palomäki et al [26]. Monitoring the process of recrystallization of amorphous samples using Raman spectroscopy was initiated 10 minutes after completion of sample cooling in all experiments.…”

Section: Raman Spectroscopymentioning

confidence: 99%

“…Raman spectroscopy is non-invasive, non-destructive and rapid method, which is suitable for real-time monitoring of amorphous-crystalline transitions. [26,29] The measurements had an integration time of 0.5 seconds and one measurement was the result of three averaged scans. During the recrystallization experiments spectra were collected with 30-second intervals in four different temperatures: well below onset of T g (17.2±0.3 °C), slightly below onset of T g (21.7±0.2 °C), slightly above onset of T g (23.9±0.4 °C) and well above onset of T g (27.5±0.2 °C).…”

Section: Raman Spectroscopymentioning

confidence: 99%

Effect of headspace gas on nucleation of amorphous paracetamol

Palomäki

Yliruusi

Ehlers

2019

Journal of Drug Delivery Science and Technology

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In this paper, the effect of the gaseous environment on recrystallization of amorphous paracetamol was investigated. The experiments were conducted with a headspace gas consisting of dry air, dry carbon dioxide, dry nitrogen and humid air in four temperatures ranging from 5 ˚C below onset of T g to 5 ˚C above onset of T g . The recrystallization was monitored using Raman spectroscopy and subsequent multivariate analysis. In temperatures below onset of T g , the presence of oxygen delayed the onset of recrystallization, with an increasing delay with lower temperature. When comparing samples exposed to dry headspace gases, the crystallization was fastest below onset of T g when exposed to nitrogen. Being an inert gas, nitrogen did not seem to interfere with the molecules allowing them to freely find their inherent arrangement, whereas the presence of oxygen delayed the formation of stabile nuclei. Above onset of T g , no differences in onset of crystallization was detected between dry gas atmospheres. Amorphous paracetamol crystallized to form II in all measurements and the samples did not reach full crystallinity within the duration of the experiments. The results show that the headspace gas has an effect on nucleation in the amorphous sample.

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Monitoring the recrystallisation of amorphous xylitol using Raman spectroscopy and wide-angle X-ray scattering

Cited by 12 publications

References 50 publications

Molecular Mobility of an Amorphous Chiral Pharmaceutical Compound: Impact of Chirality and Chemical Purity

Molecular Mobility of an Amorphous Chiral Pharmaceutical Compound: Impact of Chirality and Chemical Purity

Triggering and acceleration of xylitol crystallization by seeding and shearing: Rheo-optical and rheological investigation

Effect of headspace gas on nucleation of amorphous paracetamol

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