Peak Tailing Possible Causes

The sensory data are inconsistent and coelution is suspected. If the solutions given above fail, then the problem may be difficult to resolve because the contamination may be occurring from an odorant that is present in such small quantities that it is only detectable by GC-O. Possible causes the separation factor a is too small, tailing of peaks is occurring, both enantiomers have the same odor, or one enantiomer is odorless. Interaction of coeluting odors may vary with small variations in the concentrations of any of the odorants the note of an odorant can vary with concentration. 

The detection and identification of polar components is also possible using simultaneous hydrolysis and alkylation. These are normally difficult or impossible to determine because they tend to remain on the column, cause peak tailing, show poor reproducibility, or lose their identity due to the formation of low molecular weight fragments. Thus, for example, methyl esters of polybasic acids and long-chain fatty acids and methyl ethers of polyhydric alcohols are formed from alkyd resins with TMAH, whereas in conventional PyGC, aldehydes are formed from polyols, and alkanes and alkenes from fatty acids (Figure 6). 

Extra-column volumes should be kept as low as possible because they affect the separation. They are one cause of band broadening and of tailing. Their contribution to band broadening is additive. If each part adds 5% to peak width the decrease in separation performance is not negligible at all. Whereas it can be difficult to modify the instrument with regard to injector and detector, it is possible to use adequate tubing to connect the parts. Adequate means capillaries with an inner diameter of 0.17 or... 

A perfect Gaussian peak is symmetrical and is hence equal to 1.0. Adequate symmetry is considered achieved as long as bands have asymmetry factors between 0.9 and 1.2. Tailing As > 1.5) and fronting (As < 0.7) can cause poor separations, and indicate possible problems of the column or the chromatographic system. 

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