Abstract In the real world, gas chromatographers often inject samples including a range of analytes, polarities and vapor pressures. The traditional discussion of splitting, as described above, assumes that all compounds are instantly vaporized in the inlet as they shoot out of the syringe and that the splitting is equal for every compound. In short, it is not. The discussion below provides a brief summary of this problem and some hints for reducing or eliminating it. Besides effects within the glass sleeve, syringe effects must also be considered, so they are discussed in the next section. Technically, this effect is termed “linearity of splitting” with a linear split implying that all compounds in the sample are split equally.
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All sample components are not subjected to the same split ratio, so discrimination is said to have occurred. The analytes discriminated against therefore produce peaks that are “too small” when compared to other peaks in the sample, so the analytes discriminated against have been subject to a higher split ratio than the others. Non-linear splitting has led to spurious results that are difficult to explain. Initially, it was believed that high molecular weight components that are subject to discrimination in the syringe needle were subjected to non-linear splitting, but this turned out not to be the case. Since factors such as complete evaporation and the flow path to and around the column head are factors in splitting, and if evaporation in the syringe needle can be ruled-out, then non-linear splitting can most likely be attributed to the sample matrix or flow path. A different solvent or glass liner should be tried. Non-linear splitting is often difficult to reproduce. There are two experiments that you can easily perform to illustrate these problems.
1. Simply fill a 10 microliter syringe with water; see how far you can squirt it
. How does this distance compare to the length of a glass sleeve? This is also illustrated in the video below, in which a fluorescent solution is ejected from 
a syringe under ultraviolet light.[5] Note the long distance that the “squirt” travels in a straight line. (Click on figure to view video. Video is 10 times slower than reality.)
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VIDEO PLAYER and pay-per-view video hosting.2. When the liquid hits the hot glass, it does not evaporate immediately. This is illustrated in the classic U.S. public service announcement “This is Your Brain on Drugs”. Note the formation of pockets of hot gas under the butter and the egg. This happens in the glass sleeve, causing higher molecule weight compounds dissolved in the solvent (the butter in this case) to be potentially left behind on the liner. Also, note that the evaporation is not always instantaneous. Biedermann shows this phenomenon by placing 0.5 mL of water onto a heated hot plate.
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3. The resulting effect inside the liner is shown in another video in which the injected liquid does not contact the sides of the glass sleeve; 
it shoots straight to the bottom. (Click figure to view video. Video is 10 times slower than reality.)
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