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501 |
VGI 2000M - Environmental Microscopy
C. L. Levoguer, Surface Measurement Systems Ltd.
J. Booth, Scientific and Medical Products Ltd., J. Davies, Optas Ltd.
Abstract
Without suitable protection, all solid and liquid substances on the surface of the Earth are subjected to atmospheric moisture or humidity. In some cases the presence of atmospheric humidity can have significant consequences for the stability or performance of particular materials. In the case of solid materials and in particular powders, these humidity-induced changes often occur at the microscopic level. A classic example would be the caking of a free flowing powder such as table salt stored for a long time in an open container in a humid environment such as a kitchen. In order to study the effect of humidity at the microscopic level, it is necessary to be able to accurately and reproducibly control the humidity above a sample on a microscope stage. The VGI 2000M accessory has been developed by Surface Measurement Systems to provide such control for light microscopy, as well as NIR, FT-IR and Raman microscopes. This short paper describes the operation of the VGI 2000M and shows the application to some real life examples.
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502 |
Measuring Raman Spectrum of Morphine Sulphate Using Jobin Yvon Labram Confocal Raman Microscope
H. Jervis, Surface Measurement Systems Ltd.
J. Booth, Scientific and Medical Products Ltd., A. Knowles, Jobin Yvon
Abstract
Whilst the DVS supplies useful and valuable information on vapour sorption, it is purely gravimetric, and is limited as to the information it can provide on the nature of interactions between the adsorbate and vapour in question. Thus the VGI has been developed to complement this technique, providing a controlled environment that can interface with already well-established techniques such as Raman and Infra-red spectroscopy, opening the door to a wealth of previously inaccessible information on vapour-sorbate interactions.
Described herein is an experiment demonstrating the use of the VGI with Jobin Yvon Labram Confocal Raman Microscope, with a sample known from DVS measurements to have a sharp transition between two hydration forms, and highlighting technical details which should be remembered when running overnight experiments.
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503 |
Validation of Homogeneity of Gas-Flow and Multi-Sampling of Dried Milk Powders Using Optical Microscopy
H. Jervis, Surface Measurement Systems Ltd, UK.
Abstract
This application note describes proof of the homogeneity of the gas flow within the sample areas together with a demonstration of how variations between 3 similar dried milk samples can be compared directly using Optical Microscopy and the advantages that direct comparison between different samples can bring.
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504 |
Water Vapour Induced Mesoporous Structure Collapse Observed by VGI and FT-IR
H. Jervis, Surface Measurement Systems, London, UK
Sergei Kazarian, Andrew Chan, Imperial College London, UK
Abstract
Since the discovery of structured, mesoporous silicates by scientists at Mobil in 1991 the field of high surface area supports for heterogeneous catalysis has exploded, and the interest in these materials has directed the focus of research towards greater and tailorable pore diameters and the inclusion of catalytic species within the silica pores. Whilst the numbers of papers published in these areas increases exponentially, successful characterisation of their stability and acid/base chemistry is becoming increasingly necessary to commercialise these highly promising materials effectively, as both characteristics are extremely sensitive to synthetic and post-synthetic treatment. Described herein is the application of VGI in combination with FT-IR spectroscopy, to studies of the stability of the silica materials towards water vapour; the use of the techniques in demonstrating the differences brought about by changes in synthetic procedures, and following structural changes induced by high Relative Humidities (RH) of water vapour as they occur.
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505 |
Identifying Structural Changes in the Protein Collagen Using VGI and FT-IR
Helen Jervis, Surface Measurement Systems, UK
Paul Turner, Bruker Optics, UK
John Davies, Optas Ltd, UK
Abstract
Progress in biotechnology in recent years has precipitated renewed interest in the interaction of proteins with each other and the environment. Collagen's function as one of the fundamental structural features of biological systems makes it a protein of prime interest in areas as diverse as trans-dermal drug delivery, pre-cancerous cell diagnosis and bone regeneration. Described herein is an account of preliminary studies of the effect of RH and temperature on the protein and how VGI combined with FT-IR can be used to quickly demonstrate structural change in proteins.
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506 |
Humidity Control for MEMS (Micro Electrical Mechanical Systems)
H Jervis, Surface Measurement Systems Ltd., UK.
Abstract
The advent of MEMS (Micro Electrical Mechanical Systems) promises new advances in almost all areas of technology, but also brings with it issues that challenge the successful commercialisation of this technology. Highlighted here is the role that humidity plays in hindering the progress of this technology, and the VGI MEMS that has been developed to help resolve the issues humidity causes on the micron scale.
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507 |
Raman Spectroscopy of Hydration State Changes of Active Pharmaceutical Ingredients
H. Jervis, Surface Measurement Systems Ltd., UK.
S. Williams, P. Tampkins, Spectroscopy Products Division, Renishaw plc, UK.
Abstract
The influence of hydration states of active pharmaceutical ingredients on their crystallinity is an important factor in drug development, as changes in crystallinity also affect solubility, dissolution rate, stability and bio-availablity of the drug. Knowledge of the influence of humidity on the stability of different states therefore becomes essential from both a safety and regulatory point of view. Raman spectroscopy is an ideal tool for observing the molecular changes that occur through changes induced in the spectrum, and when used in conjunction with the VGI, can provide considerable information relating to the effects of any humidity changes on crystallinity and the packing on different functional groups of the molecules. This study focuses on the humidity induced changes occurring in two anti-inflammatory drugs used in the treatment of asthma; disodium cromoglycate, and nedocromil sodium.
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Copyright © 2008 SMS UK
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