Phenolic compounds, changes when

It is important to remember the few restrictions imposed by electrospray when considering an LC-MS analysis. Common solvents like methanol, water, acetonitrile and volatile salts (below 25 mM) like ammonium acetate and ammonium bicarbonate are acceptable in the mobile phase, whereas phosphate salts/buffers, mineral acids or other nonvolatile components cannot be used. Unfortunately, this conflicts with many of the routine mobile phases used for the analysis of phenolic compounds and anthocyanins, necessitating changes in methods when going from LC to LC-MS analyses. 

The aroma is changed when a brew is prepared from ground coffee. Caramel-like, buttery and phenolic notes become more intense. AEDA shows that this change in the aroma profile is caused by a shift in the concentrations [102]. As detailed in Table 6.52, the polar odorants are preferentially extracted by hot water leading to yields higher than 80% for S-compounds nos. 1 and 4, furanones nos. 13 and 14, vanillin (no. 20) and pentanedione (no. 28). On the other hand, the yield of the character impact odorant of ground coffee, 2-furfurylthiol, is with 19% relatively low. 

The bathochromic shift which occurs in the spectra of many phenolic compounds with change of pH may be used as the basis of a simple spectro-photometric assay (AE method) when they are present in complex formulations. A pre-requisite of the method is the absence of spectral changes of the other constituents under the same conditions. The method has been adapted by Elvidge and Peutrell for the determination of hexachloro-phane and other phenols (phenol, resorcinol, cresol and methyl hydroxy-benzoate) in various pharmaceutical products. 

The cytotoxicity of WEHT in Chang liver cells was evaluated based on its effect on cell growth (MTT test). Cell viability was greater than 95% when WEHT (0-1000 ig/mL) was incubated with cells at 37 C for 24 h. In addition, no cytotoxicity was found when Chang liver cells were treated with isolated phenolic compounds of Hsian-tsao under a concentration range of 0-100 pM (data not shown). 

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