Programmed temperature vaporizing injector

Another alternative to splitless injectors is the programmed-temperature vaporization injector (PTV). The design of this injector resembles that of a split/splitless injector, except that PTV has a lower internal volume and lower thermal mass, and as a result can be heated very rapidly. One of the... 

A recent analytical procedure by Flores et al. targeted the optimization of the interface performance in the online coupling of reversed phase liquid chromatography and gas chromatography (RPLC-GC) coupling by means of a horizontally positioned PTV (Programmed Temperature Vaporizer) injector. It improved the sensitivity achievable in the direct analysis of olive oil-mixtures with 5% or 12% of some virgin and refined hazelnut oils, respectively, based on the analysis of fil-bertone enantiomers within 30 min and without any kind of pretreatment. 

Characterization of olive oil volatiles by multi-step direct thermal desorption-comprehensive gas chromatography-time-of-flight mass spectrometry using a programmed temperature vaporizing injector. Journal of Chromatography A, Vol.1186, pp. 228-235, ISSN 0021-9673... 

Rgure 5 Programmed temperature vaporizer injector. (From Hinshaw JV and Seferovic W (1986) Programmed-temperature split-splitless injection of triglycerides comparison to cold on-column injection. Journal of High Resolution Chromatography 9 69-77.)... 

Bosboom, J.C. Janssen, H.G. Mol, H.G.J. Cramers, C.A. Large-volume injection in capillary gas chromatography 9. using a programmed-temperature vaporizing injector in the on-column or solvent-vent injection mode. J. Chromatogr. A,... 

A programmed temperature vaporizer injector (PTV) basically is a spUt-splitless injector with temperature control, i.e.. the vaporizer chamber can be heated or cooled rapidly. Three types of large volume introduction techniques can be distinguished ... 

Together with the techniques described above, other techniques using hot injectors for the transfer of large-volumes in capillary gas chromatography have been developed. Transfer of large-volume solvents in a programmed temperature vaporizing... 

A programmed-temperature vaporizer (PTV) has also been used as an interface for introducing the LC fraction to the GC unit (84,96) and to desorb the analytes retained in the SPE sorbent contained in the PTV liner. Water samples can then be injected directly in to the PTV injector. 

Numerous types of GC injectors have been manufactured over the past four decades. The most commonly used injection techniques have been reviewed and described by Grob, who correctly states that analysts must fully understand the techniques before they can make the most appropriate choice for their particular application(s). For most GC capillary column applications, the split/splitless, programmed-temperature vaporization (PTV) and on-column injectors remain the most popular. However, over the last few years, technology has progressed rapidly to provide injectors that allow more of the sample extract on to the GC column without overloading it. 

Modern GC instruments represent high resolution systems that are fully automated from sample injection to final data reduction. Utilization of new injection devices has provided the means to enhance the performance level significantly. Studies have shown, for example, that injection of the tranquilizer propio-nylpromazine and its sulfoxide into a hot injection port gave much poorer results than on-column injection at low temperature (44). In the latter case, however, nonvolatile sample components could enter the column. This disadvantage of classic sample injection can be eliminated through use of a programmed temperature vaporization (PTV) injector. 

A programmed temperature-vaporization (PTV) injector (with a sorbent-packed liner) was used to preconcentrate and inject the sample. Thermal desorption was performed and the analytes were passed to a primary column (16 m X 0.32 mm i.d., film thickness 5 p.m, 100% methyl polysiloxane) and separated according to analyte vapour pressure. Selected heart-cuts were transferred to a second column (15 m X 0.53 mm i.d., Al203/Na2S04 layer, open tubular column with 10 (im stationary phase) where final separation was performed according to chemical functionality. 

An interesting new development in injector design is the PTV (Programmed Temperature Vaporizer) [15, 16] which allows for solvent backflush in the injector. With this system, the sample can be injected at low temperature onto an adsori>ing cartridge and the non-adsorbed sample components are backflushed from the injector to vent. The temperature is then raised, vaporization of the analytes occurs and injection into the analytical column is performed. 

This injector, named PTV programmed temperature vaporizer), is conceptually similar to the split/splitless model. The temperature of the injection chamber can be programmed to effect a gradient, e.g. from 20 up to 300 °C, in a few tens of seconds (Figure 2.6). So, the advantages of the split/splitless injection are combined with those of the cold injection onto the column. 

Splitless injection is generally the preferred choice for the analysis of pesticides by virtue of its robustness. However, oncolumn and programmed temperature vaporizer (PTV) injection have also been used for this purpose. One important, interesting approach here is the direct injection of large sample volumes using a PTV injector or an Autoloop. These interfaces have been used for the determination of pesticides in water samples. ... 

Stir bar has to be removed, introduced into a glass tube, and transferred to thermal desorption instrument. After desorption and cryofocusing within a cooled programmed temperature vaporization (PTV) injector, the volatiles were transferred onto the analytical GC column. Comparison of SPME and the above-mentioned stir bar sorptive extraction (SBSE) technique using identical phases for both techniques exhibited striking differences in the recoveries, which has been attributed to ca. 100 times higher phase ratio in SBSE than in SPME. A comprehensive treatment of SBSE, discussion of the principle, the extraction procedure, and numerous applications was recently been published by David and Sandra (2007). 

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