Microwave‐assisted extraction followed by CE for determination of catechin and epicatechin in green tea

Abstract

In this work, for the first time, microwave-assisted extraction (MAE) followed by CE was developed for the fast analysis of catechin and epicatechin in green tea. In the proposed method, catechin and epicatechin in green tea samples were rapidly extracted by MAE technique, and then analyzed by CE. The MAE conditions and the method's validation were studied. It is found that the extraction time of 1 min with 400 W microwave irradiation is enough to completely extract catechin and epicatechin in green tea sample, whereas the conventional ultrasonic extraction (USE) technique needs long extraction time of 60 min. The method validations were also studied in this work. The calibration curve shows good linearity in 0.01-3 mg/mL for catechin (R(2)=0.993), and 0.005-3 mg/mL for epicatechin (R(2)=0.996), respectively. The RSD values for catechin and epicatechin are 0.65 and 2.58%, respectively. This shows that the proposed method has good reproducibility. The proposed method has good recoveries, which are 118% for catechin and 120% for epicatechin. The proposed method was successfully applied to determination of the catechin and epicatechin in different green tea samples. The experiment results have demonstrated that the MAE following CE is a simple, fast and reliable method for the determination of catechin and epicatechin in green tea.

Recent advances in the application of capillary electromigration methods for food analysis and Foodomics

“…The analysis of phenolic compounds is one of the main applications of CE in food analysis as can be deducted from the number of published works 47–71. The main food matrices analyzed by CE for determining phenol, polyphenols and pigments in the period of time covered by this review were olive oils 47–53, tea 54–59 and wine 60–62.…”

“…Cesla et al demonstrated the suitability of an offline 2D system combining HPLC (first dimension) and MEKC separation in borate buffer with SDS and heptakis‐(6‐ O ‐sulfo)‐β‐cyclodextrin (second dimension) for the separation of 25 flavone compounds and phenolic acids 57. On the other hand, Li et al described for the first time, the use of microwave‐assisted extraction followed by CZE‐UV for the fast analysis of cathequin and epicatechin in green tea 58. Uysal et al carried out the separation of cathequins and methylxanthines, namely, cathequin, epicatechin, epigallocatechin, theophylline and caffeine, in green and black tea by CEC within 30 min using a bidentate C18 column and 5 mM acetate buffer with water/ACN (80:20, v/v) as the mobile phase 59.…”

Capillary electrophoresis of natural products: Highlights of the last five years (2006–2010)

“…The wide use of UV detection was also true for food and food contaminants analyses 85, 177, 190, 196–287. However, increasing also were those exploiting CE‐MS 141, 143–145, 146, 148, 288–303.…”

“…A large number of research articles 141–145, 146, 148, 154, 161, 162, 177, 190, 195–309, 336, 337, 376–384 on CE of food/food contaminants came out during the 2006–2010 coverage. Most of these were on the determination of polyphenolic compounds, the most widely distributed secondary metabolites in plants.…”

Recent advances in enrichment techniques for trace analysis in capillary electrophoresis

“…Like SAE, the extraction efficiency of MAE is mainly affected by extraction solvent, extraction temperature, and time. The most typically used solvents include methanol , 4% H 3 BO 3 aqueous solution , acetone and water mixed solvent (3:7, v/v) , deionized water , and methanol for ultratrace triorganotin compounds, quaternary ammonium herbicides, chlorogenic acid, catechin and epicatechin, and antioxidant constituents.…”