Artifacts chemical shift

Structure calculation algorithms in general assume that the experimental list of restraints is completely free of errors. This is usually true only in the final stages of a structure calculation, when all errors (e.g., in the assignment of chemical shifts or NOEs) have been identified, often in a laborious iterative process. Many effects can produce inconsistent or incorrect restraints, e.g., artifact peaks, imprecise peak positions, and insufficient error bounds to correct for spin diffusion. 

Fig. 5.5.5 1 D CSI datasets showing the extent of conversion during a batch reaction. The form of the feature identified as peak B is associated with a single chemical shift i.e., it is of constant form at all positions across the bed, and therefore shows that the extent of conversion is uniform throughout the bed. The low intensity horizontal streaking" effect observed in these datasets and that shown in Figure 5.5.6 are artifacts arising from the automatic phase correction applied to the data ...

J-resolved spectroscopy Two-dimensional techniques, both homo- and heteronuclear, that aims to simplify interpretation by separating chemical shift and coupling into the two dimensions. Unfortunately prone to artifacts in closely coupled systems. 

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