Feuchtigkeit und Trocknen in der pharmazeutischen Technologie

Stahl, P. Heinrich

doi:10.1007/978-3-642-53782-0

Cited by 17 publications

(7 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is noteworthy that S 14.2 shows the highest bulk porosity at zero force, indicating high cohesiveness and poor flowability. This further supports the statements of Stahl (1980) and Zografi & Kontny (1986) that water binds stoichiometrically to each anhydrous glucose unit within the starch polymer up to a water content of 10 to 1 1%. At higher water content, water binds less tightly to the polymer, becoming available for starch granule interactions.…”

Section: Tablet Parameterssupporting

confidence: 87%

Force-time Curves of a Rotary Tablet Press. Interpretation of the Compressibility of a Modified Starch Containing Various Amounts of Moisture

Leitritz

Krumme

Schmidt

1996

Journal of Pharmacy and Pharmacology

View full text Add to dashboard Cite

On a rotary tablet press, the force-time curves are segmented into three phases: the compression phase, the dwell phase during which both stress and strain are variable for plastically deforming materials and the decompression phase. The following seven parameters were investigated: the compression area (A1) and the compression slope (Slc) describing the initial phase, the area ratio (AR) and the peak offset time (t(off)) characterizing the dwell time, the decompression area (A4) and the decompression slope (Sld) describing the terminal phase and the total area under the force-time curve (Atot). AR, t(off), Slc and A1 (the last with limitations) are used for phase-specific allocation of the occurrence of plastic flow, which is found to be a function of compression force and moisture content. Tablet strength, tablet porosity and in-die bulk porosity provide additional information for comprehensive interpretation. The values of A4 for the four starch batches are not significantly different. Sld provides somewhat better information about the elastic compact recovery. In general, however, the short decompression phase seems to be inappropriate for characterization by force-time curve parameters, because it is difficult to separate machine recovery from that of the tablet. Porosity above the porosity limit of the material was found to be a prerequisite for plastic flow within the compact. When the porosity limit is reached, further densification remains elastic and leads to a reduced compact strength during expansion. The area ratio, as a robust in-process control parameter for plastically flowing formulations, is suggested as a means of preventing this effect.

show abstract

Section: Tablet Parameterssupporting

confidence: 87%

Force-time Curves of a Rotary Tablet Press. Interpretation of the Compressibility of a Modified Starch Containing Various Amounts of Moisture

Leitritz

Krumme

Schmidt

1996

Journal of Pharmacy and Pharmacology

View full text Add to dashboard Cite

show abstract

“…The water vapour absorbed to the molecules in different kinds of binding. Stahl (1980) described the sorption process as connection of water bound to the molecule connected with stuffing of pores, which correlates with the different states of water, solid-like, bound and free, investigated in organic molecules described by Zografi & Kontny (1986).…”

Section: Resultsmentioning

confidence: 79%

“…The cellulose ethers were stored under 0,11,22,32,43,57,75 and 90% relative humidity at 20 C for 14 days. Saturated salt solutions (Stahl 1980) were used to create the relative humidities.…”

Section: Storage Of Cellulose Ethers In Defined Relative Humiditymentioning

confidence: 99%

Interaction of water with different cellulose ethers: a Raman spectroscopy and environmental scanning electron microscopy study

Fechner

Wartewig

Kiesow

et al. 2005

Journal of Pharmacy and Pharmacology

View full text Add to dashboard Cite

Different non-ionic cellulose ethers like methyl cellulose (MC), hydroxypropyl cellulose (HPC) and hydroxypropylmethyl cellulose (HPMC) were investigated. The characterization of the cellulose ethers was carried out by thermogravimetry and sorption/desorption isotherms. Differences in the properties of the cellulose ether films were described by time-dependent contact angle measurements. Changes in molecular structure of the raw materials, gels and films caused by water contact were studied using Raman spectroscopy. Differences between the substitution types and changes due to the gel or film formation were observed. An environmental scanning electron microscopy (ESEM) technique was used to distinguish the morphological behaviour of the cellulose ether films in contact with water. Based on in-situ ESEM experiments, the swelling and drying behaviour of the various stages of cellulose ether films (film-hydrated film-dried film) were quantified by using image analysis.

show abstract

“…In contrast, the δ 18 O values of freeze‐dried sucrose samples varied only by 1 mUr, although differences were still significant among the treatments ( P < 0.005). The observed δ 18 O variations in the sugar samples across the three 18 O‐labelled water treatments can generally be a result of two effects: (a) remaining water in the sample due to an incomplete drying process 44 or (b) exchange of anomeric oxygen atoms between carbonyl groups of the reducing monosaccharides and surrounding water molecules during the oxy‐cyclo‐tautomerisation of mutarotation 45 . For sucrose samples, the second effect can be excluded because of the lack of free carbonyl groups and because no additional compounds that would allow for isotope exchange with water were detected in the samples by HPLC/IRMS.…”

Section: Resultsmentioning

confidence: 99%

Improving the extraction and purification of leaf and phloem sugars for oxygen isotope analyses

Lehmann

Egli

Brinkmann

et al. 2020

Rapid Comm Mass Spectrometry

View full text Add to dashboard Cite

Rationale The oxygen isotopic composition (here shown as the δ18O value) of soluble sugars in leaves and phloem tissue holds valuable information about plant functions in response to climatic changes. However, δ18O analysis of sugars is prone to error, and thoroughly tested methods are lacking. Methods We performed three experiments to test if sample preparation modifies the δ18O values of sugars. In experiment 1, we tested the effects of oven‐drying versus freeze‐drying, whereas in experiment 2 we focused on the extraction and purification of leaf sugars. In experiment 3, we investigated the exudation and purification of twig phloem sugars as a function of exudation time and different ethylenediaminetetraacetic acid (EDTA) exudation media. Results Freeze‐drying produced more consistent δ18O values than oven‐drying for sucrose but not for phloem sugars. The extraction and purification of leaf sugars can be performed without a significant modification of their δ18O values; yet the purified leaf and phloem sugars possessed higher δ18O values than the fraction of water‐soluble compounds. Moreover, the exudation time significantly modulated the δ18O values of phloem sugars, which is probably related to changes in the sugar composition. The addition of EDTA did not improve the determination of the δ18O values of phloem sugars. Conclusions We show that the sample preparation of plant sugars for the reliable determination of δ18O values requires a strict protocol, which is described in this paper. For phloem sugar, we recommend a maximum exudation time of 1 h to reduce the degradation of sucrose and minimise oxygen isotope exchange reactions between the resulting hexoses and water.

show abstract

Feuchtigkeit und Trocknen in der pharmazeutischen Technologie

Cited by 17 publications

References 0 publications

Force-time Curves of a Rotary Tablet Press. Interpretation of the Compressibility of a Modified Starch Containing Various Amounts of Moisture

Force-time Curves of a Rotary Tablet Press. Interpretation of the Compressibility of a Modified Starch Containing Various Amounts of Moisture

Interaction of water with different cellulose ethers: a Raman spectroscopy and environmental scanning electron microscopy study

Improving the extraction and purification of leaf and phloem sugars for oxygen isotope analyses

Contact Info

Product

Resources

About