Large-Volume Sample Staking of Rice Polyphenols Prior to Their Determination by Non-aqueous Capillary Electrophoresis
- 219 Downloads
A rapid non-aqueous capillary electrophoretic (NACE) method for the separation of (−)-epicatechin (EPI), (+)-catechin (−CAT), kaempferol (KAE), quercetin (QUR), naringanin (NAR), ferulic acid (FA), and p-coumaric acid (p-CA) has been developed and applied to the determination of these compounds in different rice varieties. All seven compounds were separated on capillary of 50 μm × 68 cm (60-cm effective length) using 20 mmol L−1 borate buffer of pH 9.0 and 5 % acetonitrile in methanol. Large-volume sample stacking (LVSS) technique was optimized and used to preconcentrate non-detectable polyphenols of white polished rice. Rice extracts were concentrated on-line by LVSS prior to separation by non-aqueous capillary electrophoresis. An improvement of 10–55 times in detectability was achieved with injection at 50 mbar for 30 s followed by voltage inversion (−20 kV) for 5 s. Linear calibration range of 1–300 μg L−1 and 0.01–60 μg L−1 was observed for NACE and NACE-LVSS method respectively, with the detection limit of 0.33–2.0 and 0.006–0.19 μg L−1. Good reproducibility with standard deviations of less than 5 % was achieved. Polyphenol contents of different rice varieties were determined using developed method.
KeywordsPolyphenol separation Antioxidants Rice Non-aqueous capillary electrophoresis Large-volume sample staking
Compliance with Ethical Standards
Conflict of Interest
Authors declare no conflict of interest with any party.
This article does not contain any studies with human participants or animals performed by any of the authors.
- Deng GF, Xu XR, Guo YJ, Xia EQ, Li S, Wu S (2012) Determination of antioxidant property and their lipophilic and hydrophilic phenolic contents in cereal grains. J Funct Foods 4:906–914Google Scholar
- FBSGP (2013) Federal Bureau of Statistics, Government of Pakistan. Retrieved from:http://www.foodjournal.pk/Sept-Oct-2013/Sept-Oct-2013-PDF/Exclusive-article-Rice.pdf
- Irakli MN, Samanidou VF, Biliaderis CG, Papadoyannis IN (2012) Simultaneous determination of phenolic acids and flavonoids in rice using solid-phase extraction and RP-HPLC with photodiode array detection. J Sep Sci 35: 1603–1611Google Scholar
- Li LJ, Feng J, Cheng H, Chen QF, Zhong ZH, Kong HX, Wu JL (2007) Separation and determination of salicylic acid, cinnamic acid, ferulic acid and vanillic acid with sample stacking-non-aqueous electrophoresis. Chin J Anal Chem 35:401–405Google Scholar
- Markham KR, Bloor SJ (1999) Analysis and identification of flavonoids in practice. In: Rice-Evans CA, Packer L (eds) Flavonoids in Heath and Disease. Marcel Dekker, New York, p 1Google Scholar
- Vichapong J, Sookserm M, Srijesdaruk V, Svatsitang P (2010) High performance liquid chromatographic analysis of phenolic compounds and their antioxidant activities in rice varieties. Food Sci Technol 43:1325–1330Google Scholar