Chromatographic anomalies

Figure 14-11 shows contoured soil-air CO2 data collected from a depth of 1 m, overlying a breccia pipe which is heavily mineralised at depths of 150-250 m. The anomaly peak is only 0.3% CO2 (only ten times the atmospheric background) but the circular gas halo is centred over the mineralisation (Lovell and Reid, 1989 Reid and Rasmussen, 1990). The fact that these low concentrations accurately reflect mineralisation at these depths is a testament to the sensitivity and precision of the gas-chromatographic method of analysis that was used, and to the low background. 

Despite that chromatography is a relatively exact method, it has some drawbacks such as the presence of anomalies, just like any known analytical method. The anomalies that arise from chromatography are very difficult to classify. However, an attempt will be made in the following discussion to highlight the main types of anomalies in chromatographic analysis. 

There are a lot more anomalies that can arise in the use of chromatographic methods. It is not possible to discuss all of them in this short chapter. This chapter has been restricted to providing the reader highlights of the scientific and technical... 

M. Ghebregzabher, S. Ruflni, B. Monaldi, and M. Lato, A two-dimensional thin-layer chromatographic method for screening carbohydrate anomalies, y. Chromatogr. 127 133(1976). 

There are a number of books available that deal with lipids and their structures, and the author has found those cited to be of particular value [319,367]. Literally thousands of papers have appeared over the last 25 years detailing the structures and compositions of lipids from particular tissues and species, as determined by modem chromatographic methods, but there appears to have been very little effort to collate and critically compare these data in any systematic way, or to relate the compositions of lipids to their functions. Among other consequences of this, there remain anomalies and gaps in our knowledge. Comprehensive accounts of the lipids of the tissues of ruminant animals [162], tissue and membrane phospholipid compositions [395,970] and triacylglycerol compositions [125,553,686,824] have appeared, however, and there are miscellaneous reviews of the compositions of specific lipid classes or tissues in the literature. The author recently attempted to summarise the essential features of lipid composition in a succinct manner [168]. This cannot be repeated here, and a brief summary only of lipid structure and composition follows. 

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