PubMed · 4063448
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H Keller. 1985. [Solid-phase chemistry, possibilities and limits].. https://doi.org/10.1515/bmte.1985.30.10.251
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The aim of this investigation was to determine and evaluate the thermodynamic properties, i.e. heat, work, and internal energy change, of the compaction process by developing a 'Compaction Calorimeter'. Compaction of common excipients and acetaminophen was performed by a double-ended, constant-strain tableting waveform utilizing an instrumented 'Compaction Simulator.' A constant-strain waveform provides a specific quantity of applied compaction work. A calorimeter, built around the dies, used a metal oxide thermistor to measure the temperature of the system. A resolution of 0.0001 degrees C with a sampling time of 5 s was used to monitor the temperature. An aluminum die within a plastic insulating die, in conjunction with fiberglass punches, comprised the calorimeter. Mechanical (work) and thermal (heat) calibrations of the elastic punch deformation were performed. An energy correction method was outlined to account for system heat effects and mechanical work of the punches. Compaction simulator transducers measured upper and lower punch forces and displacements. Measurements of the effective heat capacity of the samples were performed utilizing an electrical resistance heater. Specific heat capacities of the samples were determined by differential scanning calorimetry. The calibration techniques were utilized to determine heat, work, and the change in internal energies of powder compaction. Future publications will address the thermodynamic evaluation of the tablet sub-processes of unloading and ejection.
High pressure homogenisation is a method for the production of nanosuspensions. In this process crystalline drug particles are pressed with high pressure through a narrow homogenisation gap. Due to the conditions in the gap it seems possible that metal erosion can occur. In this study the heavy metal (Fe) contamination of nanosuspensions produced by high pressure homogenisation was determined. Therefore nanosuspensions were analysed by atom absorption spectroscopy concerning their load of iron which is chosen as reference metal. The results show that the erosion of metal is below 1 ppm and will not cause any toxicological problems.
A reversed-phase LC method, optimised for the separation of trans- and cis-resveratrol, catechin, epicatechin, quercetin and rutin, is reported. Analyses were performed on a reversed-phase column by gradient elution. Detection was carried out by photodiode array, although the use of a fluorimetric detector considerably lowered the detection limits for catechin, epicatechin and both resveratrol isomers. Identification by the two different detection systems was based on retention characteristics, UV spectra and peak purity index were compared with commercial standards. The procedures were applied to the determination of the phenolic compounds in different types of wines and musts.