Hierarchical key for the LC-MSn identification of all ten regio- and stereoisomers of caffeoylglucose.

A chromatographic method was developed to separate all 10 regio- and stereoisomers of caffeoylglucose. Following chromatographic separation on reversed phase, the fragmentation behavior of all 10 regio- and stereoisomers of caffeoylglucose has been investigated using LC-MS(n). It is possible to discriminate between each of the isomers based on their characteristic fragment spectra and order of elution, including those for which commercial standards are not available.

Profile and characterization of the chlorogenic acids in green Robusta coffee beans by LC-MS(n): identification of seven new classes of compounds.

LC-MS(n) (n = 2-4) has been used to detect and characterize in green Robusta coffee beans 15 quantitatively minor sinapic acid and trimethoxycinnamoylquinic acid-containing chlorogenic acids, all reported for the first time from this source, with 13 of them not previously reported in nature. These comprise 3-sinapoylquinic acid, 4-sinapoylquinic acid, and 5-sinapoylquinic acid (M(r) 398); 3-sinapoyl-5-caffeoylquinic acid, 3-sinapoyl-4-caffeoylquinic acid, and 4-sinapoyl-3-caffeoylquinic acid (M(r) 560); 3-(3,5-dihydroxy-4-methoxy)cinnamoyl-4-feruloylquinic acid (M(r) 560); 3-sinapoyl-5-feruloylquinic acid, 3-feruloyl-4-sinapoylquinic acid, and 4-sinapoyl-5-feruloylquinic acid (M(r) 574); 4-trimethoxycinnamoyl-5-caffeoylquinic acid, 3-trimethoxycinnamoyl-5-caffeoylquinic acid (M(r) 574); and 5-feruloyl-3-trimethoxycinnamoylquinic acid, 3-trimethoxycinnamoyl-4-feruloylquinic acid, and 4-trimethoxycinnamoyl-5-feruloylquinic acid (M(r) 588). Furthermore, a series of structures including nine new triacyl quinic acids have been assigned on the basis of LC-MS(n) patterns of fragmentation, relative hydrophobicity, and analogy of fragmentation patterns if compared to feruloyl, caffeoyl, and dimethoxycinnamoyl quinic acids.