About Programmed Temperature Vaporising (PTV) InjectionsIntroduction
Temperature programmed sample introduction was first described by Vogt in 1979. Originally Vogt developed the technique as a method for the introduction of large sample volumes (up to 250 µL) in capillary GC. Vogt introduced the sample into the liner at a controlled injection rate. The temperature of the liner was chosen slightly below the boiling point of the solvent. The low-boiling solvent was continuously evaporated and vented through the split line.
Based on this idea Poy developed the Programmed Temperature Vaporising injector; PTV. By introducing the sample at a low initial liner temperature many of the disadvantages of the classical hot injection techniques could be circumvented. Nowadays PTV injection is generally considered to be the most universal injection technique available. Basically a PTV injection does not exist, only a PTV Inlet exist and one of the three most important modes of PTV operation are cold split injection, cold splitless injection, and solvent elimination injection (Large Volume Injection). Mostly when PTV injection is mentioned people mean a cold injection (can be split or splitless).
The programmed temperature vaporizer (PTV) inlet offers a mixture of injection possibilities, including cool sample introduction, split or splitless modes, pyrolysis, thermal desorbtion, sample concentration (solvent elimination mode); and it is column protecting. Due to this flexibility, PTV inlets are good inlets for both general analysis and trace analysis.
The OPTIC is the most advanced PTV inlet for gas chromatography, this is why we prefer MultiMode Inlet (MMI) and no longer PTV as the description of this type of inlet.
For more information about GC injection techniques, please read INJECTION TECHNIQUES FOR CAPILLARY GAS CHROMATOGRAPHY.
For information about Large Volume Injections please read LARGE VOLUME INJECTION TECHNIQUES FOR CAPILLARY GAS CHROMATOGRAPHY.