Antioxidants paper chromatography

Flavonols and flavones are present in many food products and medicinal plants and show relevant antioxidant activity in vitro. In this chapter, classical analytical methods sueh as thin layer ehromatography and two-dimensional paper chromatography together with modem methodologies such as HPLC-MS-MS are reported. Preparative ehromatography methods are also reviewed as well as spectroseopie methods used for flavonoid characterization and identification, including UV spectrophotometry and MS spectrometry. Chemical and enzymatic methods used in flavonoid identification are also reviewed. 

The analysis of vulcanisates was reviewed by Burger [116] and Aulder [117]. Aulder examined the various methods that had been used for the determination of antioxidants, antiozonants and accelerators with special emphasis on paper chromatography. He evaluated and developed the methods of Miksch and Prolss [118] and Zijp [114], and refined parts of their methods. 

Wheeler [1] has reviewed the available literature on the applications of paper chromatography in the examination of polymers for antioxidants (Table 6.1). He points out that, as most antioxidants are highly polar, they cannot be efficiently separated on normal paper except by the use of highly polar mobile phases. Consequently reversed-paper chromatography [2-5] or acetylated papers [6-9] have been used to reduce the effects of tailing . Various workers have discussed the determination of antioxidants in rubber extracts [10-14]. 

Auler [20] in his detailed survey on the analysis of antioxidants and accelerators was able to reproduce Zijp s work, and in addition, he applied the same solvent systems to circular paper chromatography with satisfactory results. 

Delves [22] has described a procedure based on paper chromatography for the identification of nitrogen-containing antioxidants in synthetic aviation turbine oil formulations which, with minor modification could be applied to the analysis of plastics. His most successful solvent system for chromatography was dipropylene glycol (DPG) as the stationary phase and cyclohexane saturated with DPG as the mobile phase. 

These must be glycerol free. A solvent extraction procedure must be used prior to GC-MS [2, 5, 6]. If the sample is prepared with ion-exchange chromatography, the glycerol will remain in the neutral fraction and not be detected by GC-MS [2, 5]. Hydrochloric acid (5 N), pH paper, sodium sulfate (anhydrous), ethyl acetate (free of contaminants), diethyl ether (anhydrous, peroxide-free, and free of contaminants except 2,6-ditertbutylcresol, which is an antioxidant found in all ether), and malonic acid (26.25 mg/50 ml methanol). 

It is well known that the phenol groups (which are bonded to the aporphine ring) and the benzylic amine function are responsible for the antioxidant and free radical scavenging activities of boldine [60], In addition, the presence of hydroxyl moieties in the chemical skeleton of boldine is responsible for its lipid peroxidation inhibitory activity [61], The level of boldine in the bark of boldo is more than 6% [62], Paper electrophoresis, voltammetric method, thin-layer chromatography and gas chromatography are common analytical methods for boldine determination [63],... 

However, additives are normally combined to complement and promote their activity as a result, it is necessary to develop analytical methods for the determination of additive mixtures. Although some spectroscopic and chemical methods are used, it is preferable to use separation methods for this purpose. Most analytical methods used to determine food additives are based on chromatographic techniques, although several recent papers have demonstrated the usefulness of electrophoresis for the analysis of food colors, sweeteners, antioxidants, and/or preservatives. The separation of food colors has received most attention, with a number of articles published on both capillary zone electrophoresis and micellar electrokinetic chromatography. 

The antioxidants BHA, BHT, and TBHQ were mostly investigated in the literature. A review (KaroviCova and Simko, 2000) devoted to the determination of phenolic antioxidants in food by high-performance liquid chromatography (HPLC) presented 24 analytical methods (papers). Eighteen of them investigated at least one of the three antioxidants and nine of them showed the determination of the three antioxidants simultaneously. Andre et al. (2010) conducted a more complete review, and once again, articles... 

Diarylheptanoids from the rhizomes of Alpinia officinarum were isolated by column chromatography and HPLC. Normal phase column chromatography followed by semi-preparative reversed-phase HPLC was used to isolate five diarylheptanoids, which were identified as 5-hydroxy-7-(4"-hydroxy-3 "-methoxyphenyl)-1 -phenyl-3-heptanone (AO-1), 5-methoxy 7 (4"-hydroxy-3"-methoxyphenyl)-l-phenyl-3-heptanone (AO-2), 7-(4"-hydroxyphenyl)-l-phenylhept-4-en-3-one (AO-3), 7-(4"-hydroxy-3 "-metiioxyphenyl)-l -phenyl-hept-4-en-3-one (AO-4), l,7-diphenylhept-4-en-3-dne (AO-5). This paper discusses the separation and isolation of these compounds and their biological as well as antioxidant activity. 

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