Inverse Gas Chromatography: Investigating Whether the Technique Preferentially Probes High Energy Sites for Mixtures of Crystalline and Amorphous Lactose

Newell, Helen; Buckton, Graham

doi:10.1023/b:pham.0000036918.79205.4b

Cited by 42 publications

(33 citation statements)

References 6 publications

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“…The results on K a are from 0.086 to 0.104 and K b 0.341 to 0.558. Higher surface energy parameters can be attributed to increased amorphicity of the sample as known from the literature on lactose or indomethacin (22,23 One of the simplest means of studying the interactions of water molecules with powdered polymeric materials are moisture sorption isotherms obtained by the dynamic vapour sorption analysis (24). The results on water vapour sorption on all the measured MCCs are in good agreement with previously published results.…”

Section: Physicochemical Properties Of MCC Powders That Could Influensupporting

confidence: 85%

Influence of different types of commercially available microcrystalline cellulose on degradation of perindopril erbumine and enalapril maleate in binary mixtures / Vpliv različnih tipov komercialno dostopne mikrokristalne celuloze na razpad erbuminijevega perindoprilata in enalaprilijevega maleata v binarnih zmeseh

Vehovec¹,

Gartner²,

Planinšek³

et al. 2012

Acta Pharmaceutica

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Numerous types of microcrystalline cellulose (MCC) are available on the market for a variety of uses in pharmaceutical industry. They can be used as adsorbents, anti-adherents, binders/diluents and tablet disintegrants (1). On the industrial scale, MCC is obtained by hydrolysis of wood and cotton cellulose using dilute mineral acids. The treated pulp is then rinsed and spray-dried with or without an additional process step such as milling. Cellulose from different sources differs in the properties such as crystallinity, moisture content, surface area, porous structure, molecular mass. These properties can be also affected by the conditions of hydrolysis. Preparations of MCC from materials other than wood and cotton (e.g., water hyacinth, coconut shells, wheat and rice straws, etc.) have also been reported (2). Influence of some commercially available types of microcrystalline cellulose (MCC) on the stability of certain active pharmaceutical ingredients (APIs), when in contact, has been investigated. Two structurally similar APIs, perindopril erbumine (PER) and enalapril maleate (EM), both well-known angiotensin-converting enzyme inhibitors were used. The main properties of an MCC that could determine the stability for each API were measured and correlated to the stability of these two APIs in binary mixtures. The stability of these APIs differed when in contact with different types of MCC. The dominant properties of MCC from one manufacturer were surface features that influenced the stability of PER and acidity that influenced the stability of EM. In the case of MCC from other manufacturers, unbound water was stability determining for both substances.

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Section: Physicochemical Properties Of MCC Powders That Could Influensupporting

confidence: 85%

Influence of different types of commercially available microcrystalline cellulose on degradation of perindopril erbumine and enalapril maleate in binary mixtures / Vpliv različnih tipov komercialno dostopne mikrokristalne celuloze na razpad erbuminijevega perindoprilata in enalaprilijevega maleata v binarnih zmeseh

Vehovec¹,

Gartner²,

Planinšek³

et al. 2012

Acta Pharmaceutica

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“…To account for the fact that probes preferentially adsorb to higher energy sites 69 , we use a Boltzmann distribution to calculate the relative occupancy of each site, shown in equation 12…”

Section: Simulationsmentioning

confidence: 99%

Differentiating Defect and Basal Plane Contributions to the Surface Energy of Graphite Using Inverse Gas Chromatography

et al. 2016

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Historically, reported values for the surface energy of graphite have covered a very wide range. Here we use finite-dilution inverse gas chromatography (FD-IGC) to show that the dispersive component of the surface energy of graphite has contributions from edge and basal plane defects as well as from the hexagonal carbon lattice. The surface energy associated with the defect-free hexagonal lattice is measured at high probe-coverage to be 63±7 mJ/m 2 , independent of graphite type. However, the surface energy measured at low probe coverage varied from 125-175 mJ/m 2 depending on the graphite type. Simulation of the FD-IGC output for different binding site distributions allows us to associate this low-coverage surface energy with the binding of probe molecules to high energy defect sites. Importantly, we find the rate of decay of surface energy with probe coverage to carry information about the defect density. By analysing the dependence of these properties on flake size, it is possible to separate out the contributions of edge and basal plane defects, estimating the basal plane defect content to be ~10 15 m -2 for all graphite samples. Comparison with simulation gives some

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“…The usual procedure of measuring surface energies by IGC is at infinite dilution where very small concentrations of probe vapours (<0.03 p/p 0 ) are injected. These small concentrations of adsorbates is thought to preferentially interact with the higher energy sites on the material surface and the interaction with lower energy sites of the adsorbent would be limited, if not excluded (13). Therefore, the measured energy may be higher than that measured from contact angle when the energy is expressed as an average of the probed area or surface sites.…”

Section: Introductionmentioning

confidence: 99%

Determination of surface heterogeneity of d-mannitol by sessile drop contact angle and finite concentration inverse gas chromatography

Hinder

Watts

et al. 2010

International Journal of Pharmaceutics

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Inverse Gas Chromatography: Investigating Whether the Technique Preferentially Probes High Energy Sites for Mixtures of Crystalline and Amorphous Lactose

Abstract: IGC does not simply measure the high-energy sites in the packed column, but equally there is a complex process that results in measured data on mixtures not being a weighted mean of the surface energy of the two components.

Cited by 42 publications

References 6 publications

Differentiating Defect and Basal Plane Contributions to the Surface Energy of Graphite Using Inverse Gas Chromatography

Determination of surface heterogeneity of d-mannitol by sessile drop contact angle and finite concentration inverse gas chromatography

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