Determination of flavonoids by high-performance liquid chromatography and capillary electrophoresis

The compounds of flavonoid, an important group in nature, can prevent coronary heart disease and anticancer by virtue of the characteristics of antioxidation. Nine flavonoids most often seen in grape wine, namely apigenin, baicalein, naringenin, luteolin, hesperetin, galangin, kaempferol, quercetin, and myricetine, were determined by means of high-performance liquid chromatography (HPLC) and capillary zone electrophoresis (CZE) in this work. A successful resolution was obtained from an unusual additive of tetrahydrofuran in mobile phase by HPLC. One notable thing is that the mixture of luteolin and quercetin could be separated for the first time by HPLC. In addition, the better detection limit was still attainable even with the use of tetrahydrofuran. The detection limits of CZE performed in borate buffer were hundreds-fold better than in previous reports. Furthermore, the retention and migration behavior of the analytes studied were discussed. As the result of this study, the elution order of flavone and flavonone was reversed to the contention proposed by Wulf et al. It was predictable from the interaction with tetrahydrofuran. Consequently, the extracts from grape wine with solid-phase extraction were analyzed by developing methods of HPLC and CZE. The obtained recoveries ranged from 90 to 107% and the relative standard deviations were under 6.3%.     

Determination of linear alkylbenzenesulfonates by high-performance liquid chromatography and capillary zone electrophoresis

High-performance liquid chromatography and capillary zone electrophoresis have been used for the separation of homologues and structural isomers of linear alkylbenzenesulfonates with subsequent UV detection. The analytical advantages of these techniques are applied to the analysis of technical products containing high amounts of LAS as well as river water samples with very low LAS concentrations using preconcentration steps.Dedicated to Professor Dr. H. Kriegsmann on the occasion of his 70th birthday     

Determination of free L- and D-alanine in hydrolysed protein fertilisers by capillary electrophoresis

of racemisation of hydrolysed protein fertilisers (HPFs) using an The objective of this study was to determine the degree inexpensive and easy to handle analytical method for qualitative control of the products. Using a polyacrylamide coated capillary and a run buffer containing 0.1 M Tris-borate+2.5 mM EDTA-Na2+0.1% sodium dodecylsulfate+10 mM beta-cyclodextrin a quantitative separation of D- and L-alanine (Ala) was made from an not treated HPF sample derivatised with dansyl chlorine by capillary electrophoresis. The D-Ala:[D-Ala+L-Ala] ratio, called degree of racemisation (RD), was calculated. The analysis of ten commercial HPFs has shown that more than 60% of HPFs have an RD > or = 40%. while only one product has shown an RD <5%. These results showed that most of the HPFs on the market are obtained with strong hydrolytic processes and high contents of D-amino acids are probably less effective as plant nutrients or even potentially dangerous to plants.     

Pesticides analysis by liquid chromatography and capillary electrophoresis

Nowadays, a wide range of pesticides are used in agricultural production, and their monitoring in samples of environmental and alimentary interest is of extreme importance to ensure, among others, the safety of consumption of foods. The aim of this work is to provide updated information about the major developments in CE and HPLC in pesticide analysis, covering relevant publications between 2004 and early 2006. The use of different sample pretreatment steps to provide a suitable extraction of these compounds from the different matrices as well as to increase the sensitivity of the determination is also discussed.     

Determination of moutan tannins by high‐performance liquid chromatography and capillary electrophoresis

Cortex Moutan (Radicis Cortex Moutan), the dried root bark of Paeonia moutan and P. spp., contains a series of water‐soluble tannins. With the eight components, 1 4,6‐di‐O‐GG (4,6‐di‐O‐galloyl‐D‐glucose), 2 1,2,3,6‐tetra‐O‐GG, 3 1,2,3,4,6‐penta‐O‐GG, 4 1,3,4,6‐tetra‐O‐GG, 5 3,4,6‐tri‐O‐GG, 6 1,3,6‐tri‐O‐GG, 7 3,6‐di‐O‐GG, and 8 1,2,6‐tri‐O‐GG, as marker substances, a rapid and efficient method of analysis based on HPLC and CE was developed. Using a phosphate eluent, a 5C18‐MS separating column, and a detection wavelength of 280 nm, HPLC was successfully used to analyze the eight constituents within 60 min. The analysis can be completed within 50 min, using the MEKC mode with a buffer composed of borate, SDS, and isopropanol, and a detection wavelength of 210 nm. The detection limit for the marker substances varied from 0.04 to 0.93 μg/mL for the HPLC method and 0.02 to 0.36 μg/mL for the CE method.     

Determination of Triton X-100 in influenza vaccine by high-performance liquid chromatography and capillary electrophoresis

Triton X-100 is applied to influenza vaccines at different stages of the manufacturing process to prevent aggregation and precipitation of biomolecules. Furthermore it is used to disintegrate the virus particles in split vaccine and to guarantee the homogeneity during production and utilisation. The final concentration of Triton X-100 has to be determined because the concentration changes in manufacturing process. The determination of the total amount of Triton X-100 as well as the separation of its ethylene oxide oligomers was possible with high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE). In HPLC a change of the column and eluent was necessary, in CE different electrolytes were used for the various separation effects. The HPLC method for the analysis of total Triton was preferred for the quantification of Triton X-100 in influenza vaccine because of better linearity, reproducibility and detection sensitivity compared to CE. In the end products an average concentration of 0.117 mg/mL was found. Received: 19 December 1996 / Revised: 27 February 1997 / Accepted: 6 March 1997     

Separation of stilbenes by capillary electrophoresis and high-performance liquid chromatography

Stilbenes, fluorescence whitening agents (FWAs), are usually added to cleaning agents in household and in industry. Capillary electrophoresis (CE) was often applied to separate various compounds simultaneously for its multinomial advantages. In this paper, we established analytical methods of six diaminostilbenes with CE and ion-pair chromatography (IPC). The optimum mobile phase for IPC was 11.78 mM tetrabutylammonium hydrogen sulfate (TBA) aqueous and acetonitrile. An IPC method has been developed for simple and direct separation for diaminostilbenes, anionic substances, with TBA as ion-pair reagent. Satisfactory linear ranges (7.0 x 10(-3) approximately 3.0 x 10 microg/mL), correlation coefficients (0.9992-0.9999), and detection limits (6-13 ng/mL) were obtained. Separations were also performed by capillary zone electrophoresis (CZE) using a buffer consisting of Tris (pH 10.1), n-tetradecyltrimethylammonium bromide (TTAB) and acetonitrile. A linear range of 5.0 x 10(-1) - 4.0 x 10 microg/mL, correlation coefficients between 0.9975 and 0.9998, and detection limits between 337 and 446 ng/mL were obtained. In particular, the separation of a pair of similar compounds (mass difference of 2) was achieved by addition of TTAB. The optimum analytical methods of CE and high-performance liquid chromatography (HPLC) were applied to commercial household with direct analysis and standard addition. No significant bias were shown between them by t-test at 95% confidence level.     

Chiral separation of quinolones by liquid chromatography and capillary electrophoresis

The quinolones are derivatives of oxoquinolines and mostly known for their antibacterial and antiviral activities. Many quinolones are chiral compounds having asymmetric centers and important due to their enantioselective biological activities. In order to study the biological activities of quinolone enantiomers, to control the manufacturing of homochiral drugs and to prepare necessary quantities of pure enantiomers for preclinical or clinical trials, respective chiral separation methods are urgently needed. In this context, the present review discusses chromatographic and electrophoretic methods for the enantioseparation of chiral quinolones and provides some useful information on their physical and pharmaceutical properties. The drawbacks of currently used techniques are revealed and ways to overcome them are outlined. Moreover, recommendations for an optimal choice of a separation protocol are given.     

Analysis of enzymatically glucosylated flavonoids by capillary electrophoresis

HPCE with UV detection was applied to the analyses of enzymatically glucosylated flavonoids, which are used as natural food additives in Japan. Four items, which have flavonol or flavanone as aglycone, were analyzed. Each of these items is a mixture of glycosides with various lengths of maltooligosaccharide chain. On capillary zone electrophoresis with an untreated fused-silica capillary at alkaline pH, glycosides with longer sugar chains migrated more rapidly. Flavonol glycosides with 1-13 glucose units were distinguished with the borate buffer (pH 10.0). Flavanone glycosides needed higher pH values for good separation than flavonol glycosides.     

Determination of 3-methylhistidine in hydrolysed proteins by fluorescamine derivatization and high-performance liquid chromatography

A method is described for the determination of the 3-methylhistidine content in myofibrilar proteins (myosin and actin) using reversed-phase high-performance liquid chromatography with ultraviolet detection. Proteins were hydrolysed and free amino acids were derivatized with fluorescamine. Elution was performed isocratically with acetonitrile-water (24:76). This method allows the detection of picomole amounts of 3-methylhistidine in myosin and actin.     

毛细管液相色谱法分离植物内源激素

建立了毛细管液相色谱法(CLC)同时分离测定4种植物内源激素的方法.采用硅胶基质ODS整体柱(27 cm×100 μm i.d.)作为分离柱,以带有光程为3 mm的光纤检测池的紫外检测器作为检测手段,在室温下以含10 mmol/L乙酸(pH 3.0)的V(甲醇):V(水)＝35:65为流动相,以0.6 μL/min的流速进行等度洗脱.采用溶剂梯度效应和扩展光程的检测池来提高检测灵敏度,该方法测定4种植物内源激素的检出限(S/N=3)在27.7～196.1 ng/mL之间,峰面积和保留时间的相对标准偏差(RSD)小于2.8%.方法已用于不同种类玉米样品的测定.     

Determination of organic acids in air by capillary electrophoresis and ion-exclusion chromatography

Summary A capillary electrophoretic (CE) method for the determination of organic acids in the low ppm range is described. The buffer consisted of 5 mM 2,6-pyridinedicarboxylic acid and 0.5 mM cetyltrimethylammonium bromide, pH 5.6. The former served as background electrolyte for indirect UV detection at 200 nm, whereas the latter was used to reverse electroosmotic flow. In <5 min 8 low molecular mass organic acids (oxalic, formic, malonic, glutaric, glycolic, acetic, lactic and propanoic) and two inorganic acids (hydrochloric and sulphuric) were separated. Detection limits for anions tested were 0.04 mg L⁻¹ (lactic acid) to 0.6 mg L⁻¹ (malonic acid). The method was applied to the determination of organic acids in air samples. The CE results when compared with ion-exclusion chromatography (IEC) agreed well. The use of electrokinetic injection in CE proved beneficial for preconcentration of organic acids in real samples. Using electrokinetic injection, preconcentration factors ranging from 14 (hydrochloric acid) to 3 (propanoic acid) were obtained. Presented at Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 1–3, 1999     

Analysis of benzyldimethyldodecylammonium bromide in chemical disinfectants by liquid chromatography and capillary electrophoresis

Two novel analytical methodologies using capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC) were developed and compared for the determination of benzyldimethyldodecylammonium bromide (BAB) in commercial compound chemical disinfectants. The LC analysis was performed with a Kromasil C18 (200 mm x 4.6 mm, 5 microm) column and a mobile phase of A:B = 80:20 (A: acetonitrile, B: 4 mmol/L octanesulfonic sodium--0.02 mol/L acetic sodium, adjusted with acetic acid to pH 5.2) at a flow rate of 1.0 mL/min. Detection was by ultraviolet absorption at 262 nm. The CE analysis was performed in a bare fused-silica capillary with 75 microm i.d. and total length of 46.4 cm with a buffer solution of 50% acetonitrile -50 mmol/L NaH2PO4, pH 2.24. The applied voltage was 20 kV. Detection was by ultraviolet absorption at 214 nm. Under optimized conditions, the HPLC retention time and CE migration time for BAB was 9.18 and 5.08 min, respectively. Calibration curves of peak area versus concentration gave correlation coefficients of 0.9996 for HPLC and 0.9994 for CE. The detection limits for HPLC and CE were 1.6 mg/L and 0.2 mg/L, respectively. Average recoveries at three concentration levels (50, 100, 200 mg/L for HPLC: 20, 40, 100 mg/L for CE) were 99.94 +/- 1.5, 99.64 +/- 1.3 and 99.61 +/- 0.4% for HPLC and 120.47 +/- 2.6, 102.06 +/- 8.7 and 103.05 +/- 3.0% for CE, respectively. Although both methods were shown to be suitable for the determination of BAB in commercial disinfectant compounds, CE provided analysis with less solvent purchase/disposal and better column efficiency, whereas HPLC provided superior precision.     

Analysis of tea components by high-performance liquid chromatography and high-performance capillary electrophoresis

Tea is one of the most popular beverages in the world. The number of reports on the analysis of tea components, especially for catechins, has recently been increasing. We review the recent reports on the analysis of tea components using the analytical methods of high-performance liquid chromatography and high-performance capillary electrophoresis.     

Analysis of carbohydrates in glycoproteins by high-performance liquid chromatography and high-performance capillary electrophoresis

We describe two methods for the analysis of oligosaccharide chains in glycoproteins by high-performance liquid chromatography (HPLC) and high-performance capillary electrophoresis (HPCE).O-andN-glycosidically linked oligosaccharides released from glycoproteins can be identified as their borohydride-reduced forms by anion-exchange HPLC with pulsed amperometric detection.N-Glycosidically linked oligosaccharides can also be analyzed as 2-aminopyridine derivatives by HPCE in direct zone electrophoresis mode in an acidic phosphate buffer and zone electrophoresis mode as borate complexes in an alkaline buffer. We also present a convenient procedure for the analysis of the constituent monosaccharides of these oligosaccharides chains by HPLC based on reversed-phase partition mode as 1-phenyl-3-methyl-5-pyrazolone derivatives.     

Chemical modification of analytes in speciation analysis by capillary electrophoresis, liquid chromatography and gas chromatography

Chemical modification of target analytes is widely used in modern analytical methods. This review focuses on the application of chemical modification techniques is the simultaneous analysis of metallic species by capillary electrophoresis, liquid chromatography and gas chromatography. Emphasis is placed on the procedures relating to analyses carried out by capillary electrophoresis. The development of this topic in the past five years is evaluated for liquid chromatography and gas chromatography. The advantages, performance and application in real samples are compared for the three techniques.     

Advances in capillary electrophoresis: the challenges to liquid chromatography and conventional electrophoresis

In the 1980s, capillary electrophoresis (CE) developed rapidly into a first-class analytical separation technique. Its advances in instrumentation and method development will not only enhance or complement existing mature separation techniques such as liquid chromatography and conventional slab gel electrophoresis, but will also severely challenge these separation methods. A brief overview of the most striking achievements of CE in the 1980s is given. which illustrates the challenges to liquid chromatography and conventional slab gel electrophoresis, and some detailed discussions are presented to highlight the advantages of CE. New developments in CE that can be expected for the 1990s include especially column technology, separation chemistry and instrumentation, which will serve further to diversify and improve the applicability of this technique in areas which are poorly addressed by other separation methods. This paper considers and speculates on the technological advancements that can be expected to emerge for CE in the 1990s.     

Determination of enantiomers in a synthetic argininal peptide using capillary zone electrophoresis and high-performance liquid chromatography

SCH 201781 is a synthetic argininal peptide containing two chiral centers and an aromatic sulfonamide group. It can exist as four reversible forms, the aldehyde, the hydrate, and two diastereomeric aminals. Capillary zone electrophoresis (CZE) and reversed-phase high-performance liquid chromatographic (HPLC) methods were developed to separate and quantitate the enantiomers in SCH 201781. Comparable results were obtained using both methods. The CZE method uses direct injection, while the HPLC method requires a precolumn derivatization and is more time consuming. The CZE method provides superior sensitivity to the HPLC method. Both methods were shown to be precise and reproducible.     

Affinity liquid chromatography and capillary electrophoresis of seminal plasma proteins

Interactions of boar, bull, and human seminal plasma proteins with heparin and phosphorylcholine were studied by affinity LC using heparin immobilized to a Toyopearl support. A step gradient elution from 0.15 to 1.50 M NaCl was employed to elute the seminal plasma proteins. Relative amounts of the heparin-binding fraction of seminal plasma proteins (H+) in seminal plasma of three species were determined. Further on, the fraction of seminal plasma proteins interacting with phosphorylcholine-binding proteins (P+) was evaluated. P+ proteins were not found in human seminal plasma and their highest amount was present in bull seminal plasma. A CE method was developed for separation of seminal plasma proteins. Various capillaries and separation conditions were tested; the best resolution was obtained in a bare-silica capillary, with a micellar system consisting of a 0.02 M borate buffer and 0.05 M SDS pH 10.0. The optimized conditions were applied to the identification of the components in boar plasma.     

Determination of hydrolyzable tannins in the fruit of Terminalia chebula Retz. by high-performance liquid chromatography and capillary electrophoresis

A RP-HPLC method for determining fourteen components (gallic acid, chebulic acid, 1,6-di-O-galloyl-D-glucose, punicalagin, 3,4,6-tri-O-galloyl-D-glucose, casuarinin, chebulanin, corilagin, neochebulinic acid, terchebulin, ellagic acid, chebulagic acid, chebulinic acid, and 1,2,3,4,6-penta-O-galloyl-D-glucose) in the fruit of Terminalia chebula Retz. is described. The separation was achieved within 80 min using a binary gradient with mobile phases consisting of a pH 2.7 phosphoric acid solution and an 80% CH3CN solution. Capillary electrophoretic analyses were also attempted, and it was found that CZE (25 mM Na2B4O7, 5 mM NaH2PO4, pH 7.0) was an efficient method for the separation of gallotannins, while an MEKC method (25 mM Na2B4O7, 5 mM NaH2PO4, 20 mM SDS, pH 7.0, and 10% acetonitrile) provided a better separation for most of the tannins examined. The HPLC and CE methods developed were both successfully applied to the assay of tannins in commercial samples of Chebulae Fructus.