Optimization of CZE for analysis of phytochemical bioactive compounds

Investigation of six bioactive anthraquinones in slimming tea by accelerated solvent extraction and high performance capillary electrophoresis with diode-array detection

A rapid and effective method for effective separation and rapid simultaneous determination of six bioactive anthraquinones by capillary zone electrophoresis was developed. An accelerated solvent extraction procedure was used for the extraction of anthraquinones from slimming tea. Under the optimized conditions, the effective separation of six anthraquinones was achieved within 8 min. Good linearity was achieved, with a correlation coefficient (r) of ⩾ 0.999. The limit of detection ranged from 0.33 to 1.40 μg mL(-1). The intra- and inter-day relative standard deviation (RSD) of the six analytes was in the range of 2.3-3.9% and 3.2-4.9%, respectively. The average recovery of the six analytes from real tea samples was in the range of 86.15-98.30% with the RSD of 1.04-4.99%. The developed and validated method has speediness, high sensitivity, recovery and precision, and can be applied for the quality control of slimming tea.

Simultaneous determination of seven phenolic acids in three Salvia species by capillary zone electrophoresis with β-cyclodextrin as modifier

A capillary zone electrophoresis method was developed for the simultaneous determination of seven phenolic acids, including protocatechuic aldehyde (1), salvianolic acid C (2), rosmarinic acid (3), salvianolic acid A (4), danshensu (5), salvianolic acid B (6), and protocatechuic acid (7), in Danshen and related medicinal plants. A running buffer composed of 20 mM sodium tetraborate adjusted to pH 9.0, and containing 12 mM β-cyclodextrin as modifier. Baseline separation was achieved within 17 min running at the voltage of 20 kV, temperature of 25°C and detection wavelength of 280 nm. The relative standard deviations of migration time ranged from 0.2 to 0.7% and the peak area ranged from 1.5 to 3.7% for the seven analytes, indicating the good repeatability of the proposed method. The method was extensively validated by evaluating the linearity (R(2) ≥ 0.9992), limits of detection (0.14-0.36 μg/mL), limits of quantification (0.47-1.19 μg/mL), and recovery (96.0-102.6%). Under the optimum conditions, samples of Danshen and related medicinal plants were analyzed using the developed method with high separation efficiency.

Advance of CE and CEC in phytochemical analysis (2012–2013)

This article presents an overview of the advance of CE and CEC in phytochemical analysis, based on the literature not mentioned in our previous review papers [Chen, X. J., Zhao, J., Wang, Y. T., Huang, L. Q., Li, S. P., Electrophoresis 2012, 33, 168–179], mainly covering the years 2012–2013. In this article, attention is paid to online preconcentration, rapid separation, and sensitive detection. Selected examples illustrate the applicability of CE and CEC in biomedical, pharmaceutical, environmental, and food analysis. Finally, some general conclusions and future perspectives are given.

Recent advances of ionic liquids and polymeric ionic liquids in capillary electrophoresis and capillary electrochromatography

Ionic liquids (ILs) and polymeric ionic liquids (PILs) with unique and fascinating properties have drawn considerable interest for their use in separation science, especially in chromatographic techniques. In this article, significant contributions of ILs and PILs in the improvement of capillary electrophoresis and capillary electrochromatography are described, and a specific overview of the most relevant examples of their applications in the last five years is also given. Accordingly, some general conclusions and future perspectives in these areas are discussed.

Field-amplified sample stacking β-cyclodextrin modified capillary electrophoresis for quantitative determination of diastereomeric saponins

Successful simultaneous diastereomeric separation and sensitive determination of two pairs of triterpenoidal saponins have been achieved by capillary electrophoresis (CE) using β-cyclodextrin (β-CD) as a stereoselective agent to cooperate with borate complexation. A usual technique for isolation and group separation of saponins was developed as an appropriate purification step prior to the determination of individual saponins by CE. Soyasaponin I ( S1: ), azukisaponin V ( S2: ), bersimoside I ( S3: ) and bersimoside II ( S4: ) could be well separated within 14 min in a fused-silica capillary (60 cm long to the detector with an additional 10 cm to the cathode; 75 µm i.d.). The background electrolyte was borate buffer (80 mM, pH 10), containing 24 mM β-CD. The separation voltage was 14 kV with a detection wavelength of 195 nm. The sample was electrokinetically injected using a voltage of 16 kV for 12 s. Methanol (70%) was used as the diluent for field-amplified sample stacking after hydrodynamic injection of short water plug (5 cm, 4 s). The method was partially validated for linearity, repeatability, reproducibility, limits of detection and limits of quantification. The correlation coefficients of the calibration curves were all >0.998, and the recoveries were from 98.23 to 96.21%.

CE and CEC of nucleosides and nucleotides in food materials

Dietary nucleosides and nucleotides play an important role in the maintenance of functions of bone marrow hematopoietic cells, intestinal mucosa, and brain. Therefore, analysis of those compounds in food is very important for improving and assuring food quality. This review summarized the application of CE and CEC in the analysis of nucleosides and nucleotides in food. The sample preparation and detection are also discussed.

Application and potential of capillary electroseparation methods to determine antioxidant phenolic compounds from plant food material

Antioxidants are one of the most common active ingredients of nutritionally functional foods which can play an important role in the prevention of oxidation and cellular damage inhibiting or delaying the oxidative processes. In recent years there has been an increased interest in the application of antioxidants to medical treatment as information is constantly gathered linking the development of human diseases to oxidative stress. Within antioxidants, phenolic molecules are an important category of compounds, commonly present in a wide variety of plant food materials. Their correct determination is pivotal nowadays and involves their extraction from the sample, analytical separation, identification, quantification and interpretation of the data. The aim of this review is to provide an overview about all the necessary steps of any analytical procedure to achieve the determination of phenolic compounds from plant matrices, paying particular attention to the application and potential of capillary electroseparation methods. Since it is quite complicated to establish a classification of plant food material, and to structure the current review, we will group the different matrices as follows: fruits, vegetables, herbs, spices and medicinal plants, beverages, vegetable oils, cereals, legumes and nuts and other matrices (including cocoa beans and bee products). At the end of the overview, we include two sections to explain the usefulness of the data about phenols provided by capillary electrophoresis and the newest trends.

CEC of phytochemical bioactive compounds

Although there are many publications related to technological or methodological developments of CEC, few focus on the analysis of natural products, especially phytochemical bioactive compounds. This review summarized the application of CEC in the analysis of phytochemical bioactive components, including flavonoids, nucleosides, steroids, lignans, quinones and coumarins, as well as fingerprint analysis of herbs. The strategies for optimization of CEC conditions and detection were also discussed.

Advanced separation methods of food anthocyanins, isoflavones and flavanols

In recent years, increasing knowledge of the positive health effects of food polyphenols has prompted the need to develop new separation techniques for their extraction, fractionation and analysis. This article provides an updated and exhaustive review of the application of counter-current chromatography, high performance liquid chromatography, capillary electrophoresis, and their hyphenation with mass spectrometry to the study of food polyphenols. Flavonoids constitute the largest class of polyphenols, widely spread in the plant kingdom and common in human diet which has been the most widely studied with respect to their antioxidant and biological activities. The main subgroups are anthocyanins, catechins, isoflavones, flavonols and flavones. They are reported to exhibit antioxidant, anti-carcinogenic, anti-inflammatory, anti-atherogenic, anti-thrombotic, and immune modulating functions, among others. Since red fruit anthocyanins, soy isoflavones and flavanols from grapes and teas are currently the most used phenolic compounds for producing new nutraceuticals and functional foods, this review is focused on these three flavonoid groups.

Determination of nucleosides and nucleobases in different species of Cordyceps by capillary electrophoresis-mass spectrometry

In present study, a capillary electrophoresis-mass spectrometry (CE-MS) method was developed for the simultaneous analysis of 12 nucleosides and nucleobases including cytosine, adenine, guanine, cytidine, cordycepin, adenosine, hypoxanthine, guanosine, inosine, 2'-deoxyuridine, uridine and thymidine in natural and cultured Cordyceps using 5-chlorocytosine arabinoside as an internal standard (IS). The CE separation conditions and MS parameters were optimized systematically for achieving good CE resolution and MS response of the investigated compounds. The optimum CE electrolyte was 100 mM formic acid containing 10% (v/v) methanol. The optimum MS parameters were as follows: 75% (v/v) methanol containing 0.3% formic acid with a flow rate of 3 microL/min was selected as the sheath liquid; the flow rate and temperature of drying gas were 6 L/min and 350 degrees C, respectively. The optimized CE-MS method was successfully applied for the simultaneous determination of 12 nucleosides and nucleobases in natural and cultured Cordyceps. On the basis of quantitative results, the total content of nucleosides is much higher in cultured Cordyceps (9138+/-4823 microg/g for cultured C. sinensis; 3722+/-1446 microg/g for C. militaris) than in natural ones (2167+/-412 microg/g). However, the hypoxanthine (131+/-47 microg/g) and inosine (335+/-90 microg/g) are much higher in natural C. sinensis. Cordycepin, which is abundant in cultured C. militaris (2276.5+/-842.6 microg/g), is only found in natural C. sinensis with very low content and cannot be detected in the cultured ones.

Pressure and electrokinetic injections for on-line sample stacking neutral analytes in microemulsion electrokinetic chromatography with salt-containing matrixes

An on-line technique for pressure and electrokinetic injections of long sample plugs with simultaneous stacking of neutral analytes (notoginsenoside R(1), ginsenoside Rg(1), ginsenoside Rf, ginsenoside Rh(1), ginsenoside Rd, ginsenoside Rg3) in microemulsion electrokinetic chromatography is presented. The effects of salt concentration, sample plug length, organic modification of the sample matrix, oil phase and SDS concentration on stacking efficiency were examined in order to optimize the two injection methods. In microemulsion electrokinetic chromatography, the effect of the type of oil and SDS content on stacking mechanism is often sophisticated. This study had demonstrated that the oil type and SDS content in microemulsion indeed markedly altered the affinity of microemulsion with analytes. Finally, in comparison with the electrokinetic injection method, the most apparent disadvantages of the pressure injection method were the relatively high LOD and poor reproducibility.

Capillary electrophoresis and microchip capillary electrophoresis with electrochemical and electrochemiluminescence detection

Recent advances and key strategies in capillary electrophoresis and microchip CE with electrochemical detection (ECD) and electrochemiluminescence (ECL) detection are reviewed. This article consists of four main parts: CE-ECD; microchip CE-ECD; CE-ECL; and microchip CE-ECL. It is expected that ECD and ECL will become powerful tools for CE microchip systems and will lead to the creation of truly disposable devices. The focus is on papers published in the last two years (from 2005 to 2006).