Oncolumn injection

In addition, the advantages of various injection techniques have been used. Oncolumn injection was used to avoid the decomposition of compounds within the injector. " A direct aqueous injection technique for the analysis of VOCs in water has been used in analysis for many years. The advantages of the direct aqueous injection technique were summarized by Gurka et al. " ... 

Catalina, M. I., Dalluge, J., Vreuls, R. J. J., and Brinkman, U. A. T., Determination of chlorophenoxy acid herbicides in water by in situ esterification followed by in-vial liquid-liquid extraction combined with large-volume oncolumn injection and gas chromatography-mass spectrometry, J. Chromatogr. A, 877, 153-166, 2000. 

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. ... 

A fused silica fiber coated with an immobilized phase of the above coatings is fixed inside a syringe. For the analysis of aqueous samples, the fiber is exposed to the liquid and the analytes are accumulated in the stationary phase imtil equilibrium is reached. The fiber is then removed from the solution and the extracted organic substances are thermally desorbed in a split-splitless or oncolumn injector of a gas chromatograph or desorbed by organic solvents and injected into HPLC system. As indicated earlier at the beginning of this section, SPME has been successfully coupled with various techniques such as GC, HPLC, CE, and MS [164-168]. 

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