the signal associated with cysteine, which was found in all samplesand is shown in Fig. 4 as component 16.Signal 10 was initially assigned to 3,4,5-trimethoxybenzoic acidowing to the distinct chemical shift, with component 11 correlatingto methyl syringate. However, the limits of the Mr predictionare made apparent when low diffusion coefficients are encountered.Whilst spiking of the samples shows that the signal at ca7.4 ppm does correlate to 3,4,5-trimethoxybenzoic acid, the internalstandards predict a mass of ca 330 g mol1. This loss of linearityat low diffusion coefficient suggests that an appropriately largerange of internal standards should cover the mass range of thecomponents of interest. In addition, the greater potential for ionisationof aryl carboxylic acids and hence increase in complexedwater contributions to the hydrodynamic radius of the moleculemay affect linearity in polar solvent mixtures. Despite spiking witha range of phenolic compounds, identified as components of manukahoneys, we were unable to conclusively identify the compoundsresponsible for signals 13, 14 and 15; however theyappear to have similar mass to methyl syringate and phenyllacticacid, respectively, as shown in Table 2. Efforts to detect wellknowncaffeoyl phenolic derivatives were unsuccessful. It is worthyof note that Mr and diffusion coefficients for all components,excluding 10, correlated well with the linear relationship derivedtừ các tiêu chuẩn nội bộ có r2 = 0,94
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