Dynamic vapour sorption

Vora, K.L. Buckton, G. Clapham, D., The use of dynamic vapour sorption and near infrared spectroscopy (DVS-NIR) to study the crystal transitions of theophylline and the report of a new solid-state transition Eur. J. Pharm. Sci. 2004, 22, 97-105. 

Dronen DM, Reineccius GA. 2003. Rapid analysis of volatile release from powders using dynamic vapour sorption atmospheric pressure chemical ionization mass spectrometry. Journal of Food Science 68 2158-2162. 

Rapid analysis of volatile release from powders using dynamic vapour sorption atmospheric pressure chemical ionization... 

The interaction of water with many materials can have a significant impact on the material properties, for example plasticisation of the glass transition temperature and stabihty. TGA measurements under controlled humidity are useful in studying the adsorption and desorption of water and for distinguishing bound and unbound water. Dynamic vapour sorption (DVS) is a similar technique and has its own class of dedicated instrumentation. A full description of this is outside the scope of this book. 

Abbreviations DSC, differentiai scanning caiorimetry DMA, dynamic mechanical analysis TGA, thermogravimetric analysis DTGA, differential thermogravimetric analysis RVA, rapid viscoanalyser DVS, dynamic vapour sorption ITC, isothermal titration calorimetry DSM/NC, differential scanning micro/nano-calorimetry. 

Within routine studies of new chemical entities, the initial focus is to explicate a comprehensive description of the drug. The aim is to provide specific information on its physical aspects such as morphological form, polymorphism, crystal habit and solvate state. This information is combined with data from other techniques such as dynamic vapour sorption (DVS), particle size analysis, XRPD (x-ray powder diffraction), solid state NMR, IR spectrophotometry and Raman spectroscopy. 

INVESTIGATION OF THE ACID-BASE PROPERTIES OF AN MCM-SUPPORTED RUTHENIUM OXIDE CATALYST BY INVERSE GAS CHROMATOGRAPHY AND DYNAMIC GRAVIMETRIC VAPOUR SORPTION... 

Dynamic vapour phase techniques are interesting tools for the determination of these properties. When compared to standard wettability experiments, they provide two main benefits. They can easily and reproducibly be applied to powders and a wide variety of probe molecules can be selected. In the current study dynamic gravimetric vapour sorption (DVS) and inverse gas chromatography (IGC) have been used to characterise the energetic and acid-base properties of a calcined ruthenium oxide / MCM41 catalyst as well as the corresponding MCM41 support. 

Dynamic gravimetric vapour sorption involves the use of an ultra-sensitive microbalance. The solid sample is placed in the sample pan at the end of the hang-down wire while the probe molecule is vaporised in an inert carrier gas stream. Adsorption of vapour is measured as a gain of weight, desorption as a loss of weight. From these changes of weight at different vapour concentrations sorption isotherms can be determined. 

A Ruthenium oxide / MCM41 catalyst as well as the pure MCM41 support were studied by inverse gas chromatography and dynamic gravimetric vapour sorption. The obtained... 

Vapour and gas sorption measurements can be performed with static or dynamic methods, either of which can provide information on equilibrium behaviour. Furthermore, the measurements can be performed using gravimetric or volumetric based instrumentation. The most common flow methods are inverse gas chromatography (IGC) [1] for volumetric studies and dynamic gravimetric instrumentation [2]. 

The difference between IGC and conventional analytical gas-solid chromatography is the adsorption of a known adsorptive mobile phase (vapour) on an unknown adsorbent stationary phase (solid state sample). Depending on experiment setup, IGC can be used at finite or infinite dilution concentrations of the adsorptive mobile phase. The latter method is excellent for the determination of surface energetics and heat of sorption of particulate materials [3]. With IGC at finite dilution, it is possible to measure sorption isotherms for the determination of surface area and porosity [4], The benefits of using dynamic techniques are faster equilibrium times at ambient temperatures. 

The dynamics of ad(de)sorption of water vapour from a carrier gas in a packed alumina column is governed by the adsorption equilibria and kinetics for the system. For the adsorption process, a mass transfer zone (MTZ) for water is formed within the column which propagates from the feed gas end to the column exit. The MTZ is generally constant... 

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