Phenolic acids chromatography analysis

HPLC) for phenolic acids analysis. When procedure (ii) was applied, the ion-exchange resin was separated from the methanol phase and eluted with three 40 ml aliquots of 80% methanol. The resin bead eluates were evaporated to dryness and subjected to spectrophotometry (Shimadzu UV 160 spectrophotometer) for total phenolics and high-performance liquid chromatography (HPLC) for phenolic acids analysis. 

Wulf, L.W. and Nagel, C.W., Analysis of phenolic acids and flavonoids by high-pressure liquid chromatography. J. Chromatogr. 116, 271, 1976. 

Reversed-phase chromatography is the most popular mode of analytical liquid chromatography for phenolic compounds. In most cases, the reported systems for the separation of phenolics and their glycosides in foods are carried out on reversed-phase chromatography on silica-based Cl8 bonded-phase columns. Occasionally, silica columns bonded with C8 were applied in the analysis of phenolic acid standards and coumarins (7), and C6 columns for the analysis of ferulic acid in wheat straw (8). 

Yu J, Vasanthan T, Temelli F. 2001. Analysis of phenolic acids in barley by high-performance liquid chromatography. J Agric Food Chem 49 4352-4358. 

Pomponio, R., Gotti, R., Hudaib, M., and Cavrini, V. 2002. Analysis of phenolic acids by micellar electrokinetic chromatography application of Echinacea purpurea plant extracts. J. Chromatogr. A 945, 239-247. 

Kivilompolo M. Hyotylainen T. 2007. Comprehensive two-dimensional liquid chromatography in analysis of Lamiaceae herbs characterisation and quantification of antioxidant phenolic acids. J. Chromatogr. A 1145 155-164. 

In general, the sample preparation and extraction steps of phenolic acid analysis are very critical to the final result. Solvent or solution composition, extraction temperature, extraction technology, acid, alkaline, or enzymatic hydrolysis, extraction time, and cleanup conditions are all factors that affect the recovery and profile of phenolic acids. Poor sample preparation and extraction result in unreliable outcomes, regardless of the precision of the chromatography quantification method. Table 3.1 lists various sample extraction methods for different types of samples. 

Single electron transfer (SET), as antioxidant mechanism 844, 896, 897 Size exclusion chromatography 953 Slash pine bark, phenolic compounds in 944 Smiles rearrangement 466-470, 759 S Ar reactions 673 Soil samples, phenolic compounds in, analysis of 932, 965, 972, 985 field screening of 938 Sol-gel technique 1082 Solid acid catalysis 612-621 Solid-phase extraction (SPE) 930-933, 936, 942, 944-950, 955, 958, 960, 962-964, 969, 972, 985, 986, 995, 1354 Solvation energy 500, 992 Solvation free energy 5 Solvatochromic comparison method, for solvent hydrogen-bond basicity 591 Solvent effects,... 

Bahorun and colleagues describe the use of thin-layer chromatography (TLC) to determine total proanthocynidins, phenol, and flavonoid content of hawthorn extracts. High-performance liquid chromatography (HPLC) analysis using a UV detector at 280 nm for proanthocyanidins and phenolic acids, and 360 nm for flavonoids is also described (Bahorun et al., 1996). 

When comparing the performance of PLRP-S, LiChrolut EN, Isolute ENV, and PGC in on-line pre-concentration followed by liquid chromatography analysis, Puig and Barcelo [230] arrived at the conclusion that LiChrolut EN and Isolute ENV are the most suitable sorbents (Table 14.1) when the whole range of phenolic compounds has to be monitored, except for 2-amino-4-chlorophenol. The latter is protonated in acidic solutions and is not retained on neutral polymers. Both Isolute ENV+ and LiChrolut EN provide very good breakthrough volumes and identically acceptable... 

The application of HPLC to studies of BaP metabolism was an important advance (414). Using reverse-phase colunms, the major metabolites of BaP formed in vitro can readily be separated, as shown in Fig. 7. Systems for separation of the minor phenolic metabolites and for the triol and tetraol metabolites of BaP have also been developed (416, 506). Metabolites are quantified by ultraviolet detection or by scintillation counting of the column eluant. The latter technique is used for mixtures with low levels of metabolites and is more successful when unmetabolized BaP is first removed by silicic acid chromatography. Addition of vitamin E to incubation mixtures prior to analysis helps retard air oxidation (365). High-performance reverse-phase columns are commercially available and have relatively long lifetimes when used for this type of work. 

MS has proved to be a very powerful technique in the analysis of flavonoids and phenolic acids mainly due to its high sensitivity and the possibility of coupling with different chromatographic techniques such as gas chromatography (GC-MS), capillary electrophoresis (CE-MS), and especially LC-MS. Nowadays, techniques such as LC-DAD-MS, and particularly LC-DAD-electrospray ionization (ESI)/MS, are regarded as necessary tools for the analysis of phenolics in natural matrices. ... 

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