TY  - JOUR
A1  - Hartwig, Anne
A1  - Hass, Roland
T1  - Monitoring lactose crystallization at industrially relevant concentrations by photon density wave spectroscopy
JF  - Chemical engineering & technology
N2  - Lactose is of great industrial importance and its production includes the cooling crystallization from highly concentrated solutions. Monitoring the crystallization process is essential to ensure reproducible product quality. Photon density wave (PDW) spectroscopy enables in-line monitoring of highly concentrated processes in liquid dispersions. It was applied to the determination of the solubility and nucleation points of lactose monohydrate in water, sizing of lactose crystals, and to dissolution as well as crystallization monitoring. Other process analytical technologies (focused-beam reflectance measurement, particle vision and measurement) were used as reference, and the comparison indicates that PDW spectroscopy is very robust against probe fouling and is, thus, a useful tool for monitoring crystallization processes in concentrated suspensions.
KW  - In-line monitoring
KW  - Lactose
KW  - Light scattering
KW  - Photon density wave spectroscopy
KW  - Process analytical technology
Y1  - 2018
U6  - https://doi.org/10.1002/ceat.201700685
SN  - 0930-7516
SN  - 1521-4125
VL  - 41
IS  - 6
SP  - 1139
EP  - 1146
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Mameri, Fatima
A1  - Koutchoukali, Ouahiba
A1  - Koutchoukali, Mohamed Salah
A1  - Hartwig, Anne
A1  - Nemdili, Leila
A1  - Ulrich, Joachim
T1  - Optimum operating conditions for manufacturing ibuprofen tablets coated with polyethylene glycol by melt crystallization process
JF  - Journal of Thermal Analysis and Calorimetry
N2  - The aim of this work is to apply the melt crystallization technology to manufacture ibuprofen tablets coated with polyethylene glycol in a single step. This technology, based on a pastillation process, allows in situ separation between two components (active ingredient and coating material). The design and application of this technique depend on the thermo-physical properties of the substances used, as well as on the existence of a eutectic point in the phase diagram. To evaluate the prerequisite conditions, first, DSC curves, allowing the construction of the phase diagram of the binary system, were investigated and the eutectic point was determined (30 mass% ibuprofen, 52 degrees C). Then, the stability of the selected mixture (10:90 mass% of ibuprofen, PEG6000) was studied by thermogravimetric analysis. Finally, the coating quality was investigated under different operating conditions including viscosity, cooling plate temperature, the power of ultrasound and seeding. This parametric study showed that seeding with PEG6000 is necessary to obtain a hemispherical pastille shape, a suitable separation and a pure and thick coating layer. In addition to the optimization of operating conditions of the in situ coating process, it was possible to determine the optimum viscosity and the cooling plate temperature (271.77 m Pa s, 25 degrees C) to obtain a uniform and crystalline coating. During the deposition of molten drops on the cooled surface, the progression of crystal growth was monitored online by optical microscopy. According to the good separation achieved and to the purity and thickness of the microscopic cross-sectional material, the in situ coating process is conceivable for the production of PEG6000-coated ibuprofen tablets.
KW  - Ibuprofen
KW  - PEG6000
KW  - Eutectic mixture
KW  - In situ coating
KW  - Melt crystallization
KW  - Pastillation
Y1  - 2019
U6  - https://doi.org/10.1007/s10973-018-7667-z
SN  - 1388-6150
SN  - 1588-2926
VL  - 136
IS  - 2
SP  - 833
EP  - 842
PB  - Springer
CY  - Dordrecht
ER  -