Parallel factor analysis selection

The gas chromatographic (GC) technique is almost exclusively used for the qualitative analysis of volatiles. The analysis of essential oils was developed in parallel with the technological developments in GC. Some of these developments were the application of more selective new column stationary phases and mass spectrometry (MS) detection devices which allow to identify the compounds. However, advances in instrumentation were not the only important factor in the development of analytical methods for essential oils in plants. Sample extraction and concentration techniques were also improved recently, in order to reduce the extraction time, to improve the extraction yield, and to enhance the quality of the extracts. The most outstanding improvements in the determination of the composition of essential oils came from the development of total analysis systems, i.e., systems where sample... 

It should be noted that accuracy of measurement of the refractive index distribution in a selfoc is influenced by such factors as focusing of beams permeating though the selfoc slice, and the sphericity and non-plane-parallelism of the sample. Analysis performed by the authors of ref. [30] indicates that the relative error of measurements produced by focusing of the beams is below 0.5%, and deviation from the plane-parallel shape of the slice by 10 pm at its thickness of 500 pm indicates the relative error of about 4% at Ak = 0.04 with accurate selection of immersion. 

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