High pressure liquid chromatography factor analysis

Analyses of Pitch. Modern analytical facilities of high-pressure liquid chromatography, gel permeation chromatography, an(j 1 nuclear magnetic resonance and mass spectrometry, associated with 1R and UV spectroscopy enable a total molecular constituent analysis of pitch composition to be obtained. The use of such information could then possibly be the route to prediction of pitch quality on carbonization. It would appear that such an approach would not be successful (ignoring the cost factor for such detailed analysis). The pitch cannot be considered as an assembly of molecules which pyrolyse independently of each other. The pitch carbonizes as a multi-phase system and experience today would indicate the impossibility of predicting all interactions, physical and chemical. 

Perkin Trans. 2, 2087 (1988). Solute-Sovent Interactions in Chemistry and Biology. Part 7. An Analysis of Mobile Phase Effects in High Pressure Liquid Chromatography Capacity Factors and Relationships of the Latter with Octanol-Water Partition Coefficients. 

Preferably, high pressure liquid chromatography (hplc) is used to separate the active pre- and cis-isomers of vitamin D3 from other isomers and allows theic analysis by comparison with the chromatograph of a sample of pure reference j-vitamin D3, which is equilibrated to a mixture of pre- and cis-isomers (82,84,85). This method is more sensitive and provides information on isomer distribution as well as the active pre- and cis-isomer content of a vitamin D sample. It is applicable to most forms of vitamin D, including the more dilute formulations, ie, multivitamin preparations containing at least 1 lU/g (AOAC Methods 979.24 980.26 981.17 982.29 985.27) (82). The practical problem of isolation of the vitamin material from interfering and extraneous components is the limiting factor in the assay of low level formulations. 

In reverse phase high-pressure liquid chromatography (RP HPLC), the mobile phase is usually an aqueous-organic mixture, permitting the phenomenological theory to be applied. LePree and Cancino carried out this analysis. The composition-dependent variable is the capacity factor k, defined by eq. [8.2.51],... 

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