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Instrument Database:
Marathon Scientific Consultants Inc. - MSIS - Multimode Sample Introduction System
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available |
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Marathon Scientific Consultants Inc.
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Sample introduction: Vapor generator
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The MSIS Chamber is designed to provide a thin film generation process, and to provide it in a convenient setup. The hydride generation process is a continuous flow design, so you can run hydrides the same as if they were just samples being pumped to a nebulizer. The sample flows down the inner cone, forming a thin film on the cone, and the hydride solution is also flowing down the same cone. As the two flow down the cone, they interact, produce hydrides, and allow the volatile molecules to immediately escape into the surrounding carrier gas that delivers them to the torch.
Thin Film Hydride Generation is a revolutionary breakthrough in anayltical chemistry. Many elements are able to be converted to volatile hydrides with this method. Elements such as Pt, Au, Ag, as well as the regular As, Se, Te, Hg, ... can produce hydrides this way.
The Theory:
Hydrides form rapidly for many elements, but while in a body of liquid, unstable hydrides break down almost immediately and convert back to the original elemental form. Only very stable volatile hydrides succeed in escaping the body of liquid. If an unstable volatile hydride can immediately be removed from the surrounding liquid, then it remains volatile in the carrying gas, and will be delivered to the flame of a spectrometer before it looses its volatility. It may well break down to its elemental form while in transit in the gas, but it does not matter - once it is in the gas flow, it will continue to the flame even as a elemental atom. So a system that enables a hydride reduction, and immediately removes the volatiles formed, will produce hydrides of many elements that are otherwise not possible to volatilizate with hydride generation techniques.
Hydride Generation in a thin film accomplishes this objective. With the liquid in a thin film on a surface, there are only a few molecules of water surrounding the unstable hydrides, so as the hydrides move in the thin film, they escape the thin film almost immediately, without time to interact with the water around. Its that simple - run the hydride generation in a thin film, and you have vast improvements in the transfer of hydrides to the gas surrounding the liquid.
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