Programmed-temperature vaporization inlet

Programmed temperature vaporization (PTV) Most versatile inlet Allows large volume injection Little-no sample degradation Effective trace (to sub-ppb) analysis Expensive Requires optimization of many parameters Not well-known... 

For capillary GC, the split/splitless inlet is by far the most common and provides an excellent injection device for most routine applications. For specialized applications, there are several additional inlets available. These include programmed temperature vaporization (PTV) cool on-column and, for packed columns, direct injection. PTV is essentially a split/splitless inlet that has low thermal mass and a heater allowing rapid heating and cooling. Cool injection, which can be performed in both split and splitless mode with the PTV inlet, reduces the possibility of sample degradation in the inlet. Capabilities of the commonly available inlets are summarized in Table 14.3. 

Gas chromatograph systems are composed of an inlet, carrier gas, a column within an oven, and a detector (O Figure 1-1). The inlet should assure that a representative sample reproducibly, and frequently automatically, reaches the column. This chapter will cover injection techniques appropriate for capillary columns. These include direct, split/splitless, programmed temperature vaporization, and cool on-column injection (Dybowski and Kaiser, 2002). 

Introduction of the sample into a cool inlet characterizes programmed temperature vaporization. A temperature program is then utilized to vaporize the sample and introduce it into the column (Dybowski and Kaiser, 2002). 

A programmed-temperature vaporization (PTV) inlet is a hybrid of the techniques described above. It is a spUt/spUtless inlet that has been modified to allow cold injection and rapid temperature programming. Similar to on-column injection, the injection occurs while the inlet is cold. In contrast, the injection is performed into a chamber, similar to the spUt and spUtless techniques. This chamber is then rapidly heated to desorb the sample into the capillary column. This inlet also allows for the injection of up to hundreds of microUters of sample. There are numerous modes in which a PTV inlet can be operated, making it perhaps the most versatile of all available inlets. 

Programmed-temperature vaporizer electronic pressure-controlled sample inlet systems -ms grade columns, solid-phase microextraction sampling techniques, large-volume injectors, integrated guard columns, multidimensional GC, sol-gel columns, improvements in silphenylene phases, advances in GC-MS, more affordable benchtop GC-MS systems... 

Programmed-temperature vaporizer, an inlet system designed to perform a temperature programmed injection, a cold injection system for direct liquid injection for split or splitless injection, solvent spHt technique and cryo-enrichment. 

In gas chromatography the most successful solution to the resolution of complex mixtures has been that of programmed temperature gas chromatography. In this technique all partition ratios are decreased over the entire length of the column with time. When a separation is started at a relatively low temperature, the partition ratios of most components are so large that they are almost completely immobilized, or frozen, at the inlet of the column. The components with small partition ratios can move normally along the column. As the temperature is raised, partition ratios decrease, and the other solutes successively reach temperatures at which they have vapor pressures that enable them to be eluted at a reasonable rate. In effect, each compound tends to be eluted at its optimum temperatme for the heating and flow rates chosen. 

VFO works well in gas turbines. In a nine-month test program, the combustion properties of VFO were studied in a combustion test module. A gas turbine was also operated on VFO. The tests were conducted to study the combustion characteristics of VFO, the erosive and corrosive effects of VFO, and the operation of a gas turbine on VFO. The combustion tests were conducted on a combustion test module built from a GE Frame 5 combustion can and liner. The gas turbine tests were conducted on a Ford model 707 industrial gas turbine. Both the combustion module and gas turbine were used in the erosion and corrosion evaluation. The combustion tests showed the VFO to match natural gas in flame patterns, temperature profile, and flame color. The operation of the gas turbine revealed that the gas turbine not only operated well on VFO, but its performance was improved. The turbine inlet temperature was lower at a given output with VFO than with either natural gas or diesel fuel. This phenomenon is due to the increase in exhaust mass flow provided by the addition of steam in the diesel for the vaporization process. Following the tests, a thorough inspection was made of materials in the combustion module and on the gas turbine, which came into contact with the vaporized fuel or with the combustion gas. The inspection revealed no harmful effects on any of the components due to the use of VFO. 

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