Programmed Temperature Gas Chromatography Apparatus

Abstract

A programmed temperature gas chromatograph is described for the rapid separation of mixtures of wide boiling point ranges. Linear heating

Precise Phase Transition Measurements of Organic Materials by Differential Thermal Analysis

“…With the exception of the temperature programmer (1), the electronic components of the DTA apparatus are commercial products for sensitive differential temperature measurement, accurate temperature measurement, and X -Y potentiometric recording. The block diagram in Figure 1 illustrates the flow of thermocouple signals and the general plan of the apparatus.…”

“…The temperature programming thermocouple is in a "feedback" circuit with a proportionally controlled linear temperature programmer (1). Temperature programming from any selected temperature is achieved by a "bucking" reference voltage, usually a thermocouple placed in a bath at the selected temperature.…”

“…Other merits of the differential thermal analysis (DTA) technique are likely to be discounted if this supposedly objective instrumental method is not shown capable of better precision and accuracy, This relatively poor precision is adequate for characterizing most inorganic systems, where transitions usually are well separated. For studies of organic 1 Present address, Sabine River Works, Orange, Tex. substances most workers have used the same techniques.…”

Gas Chromatography and Its Application to Pharmaceutical Analysis

“…Others have added small amounts of fatty acids (4, 88), their salts (89), or various surface-active agents (81, 90, 91). These tend to deactivate hydrogen bonding sites, spread the stationary phase over the surface of the support, and possibly act as a "glue" to span the interface between the liquid and the solid (91) (93)(94)(95). By increasing the temperature during the run of a chromatogram, it is possible to separate rapidly a mixture of components boiling over a wide range of temperature, and all solutes emerge as sharp, well-defined peaks of nearly the same shape (Fig.…”

“…Temperature Programing.-Because of the band broadening factors expressed in the van Deemter equation, the peaks of a normal isothermal gas chromatogram become wider and lower as the retention time increases. Furthermore, it is possible for high boiling components to go undetected because of very long retention times (93)(94)(95). By increasing the temperature during the run of a chromatogram, it is possible to separate rapidly a mixture of components boiling over a wide range of temperature, and all solutes emerge as sharp, well-defined peaks of nearly the same shape (Fig.…”