Volatile secondary metabolite pattern of callus cultures of Chamomilla recutita

The effects of various plant growth regulators and culture conditions on the production of volatile secondary metabolites from callus cultures of Chamomile (Chamomilla recutita) inflorescence were investigated and the most efficient conditions were determined. The essential oil composition was assayed by GC-MS analysis and found to contain chamomillol, gossonorol, cubenol, alpha-cadinol, (-)-alpha-bisabolol, 1-azulenethanol acetate and (-)-alpha-bisabolol acetate.     

Capillary electrochromatography of basic compounds in pharmaceutical analysis

Capillary electrochromatography (CEC) shows promising results in the separation of basic drugs. Traditional reversed-phase systems, with or without amine additives to the mobile phase to improve peak shapes, are the most commonly employed. Alternative useful stationary phases, such as strong cation exchangers and polymer-based continuous beds, are also discussed, as are methods to improve sensitivity by sample preconcentration. So far, studies performed on CEC have mainly been fundamental, but the technique is rapidly maturing and has many potential applications in the pharmaceutical field.     

Content of phenolic compounds in aerial parts of Chamomilla suaveolens from Estonia

The content of total polyphenols, flavonoids and coumarins in the aerial parts of pineapple weed (Chamomilla suaveolens (Pursh) Rydb.), growing wild in Estonia, was determined chromato-spectrophotometrically, and individual polyphenols were quantified using HPLC-DAD-MS/MS. The total content of polyphenols was rather similar in flowers (9.1-11.5%) and in whole aerial parts (8.4-10.9%) of pineapple weed. The upper one-third (1/3) and upper two-thirds (2/3) of the aerial parts contained more flavonoids (0.15 - 0.20%) than the flowers (0.12%). The content of coumarins showed no significant difference between the flowers and the upper 1/3 and 2/3 of the aerial parts. The main polyphenols in the flowers were dicaffeoylquinic acids (202-380 mkg/mL), chlorogenic acids (75-185 mkg/mL), and ferulic acid glycoside (61-124 mkg/mL). Also found were quercetin galactoside, apigenin acetylglucoside, malonylapigenin glucoside, as well as luteolin, quercetin and apigenin glycosides.     

Capillary electrochromatography and preconcentration of neutral compounds on poly(dimethylsiloxane) microchips

Capillary electrochromatography (CEC) and preconcentration of neutral compounds have been realized on poly(dimethylsiloxane) (PDMS) microchips. The channels are coated with polyelectrolyte multilayers to avoid absorption of hydrophobic analytes into PDMS. The structures of a microchip include an injector and a bead chamber with integrated frits, where the particles of the stationary phase are completely retained. Dimensions of the frit structures are 25 micro mx20 micro m, and the space between the structures is 3 micro m. A neutral compound, BODIPY, that is strongly absorbed into native PDMS, is successfully and selectively retained on octadecylsilane-coated silica beads in the bead chamber with a concentration enhancement of up to 100 times and eluted with elution buffer solution containing 70% acetonitrile. Preconcentrations and CEC separations of coumarins have been conducted with the same device and achieved complete separations in less than 50 s.     

Capillary electrochromatography of proteins and peptides

This review summarizes applications of CEC for the analysis of proteins and peptides. This "hybrid" technique is useful for the analysis of a broad spectrum of proteins and peptides and is a complementary approach to liquid chromatographic and capillary electrophoretic analysis. All modes of CEC are described--granular packed columns, monolithic stationary phases as well as open-tubular CEC. Attention is also paid to pressurized CEC and the chip-based platform.     

Capillary electrochromatography of peptides and proteins

This paper reviews recent progress in bioanalysis using capillary electrochromatography (CEC), especially in the field of separation of proteins and peptides. Fundamentals of CEC are briefly discussed. Since most of the recent developments on CEC have focused on column technology, i.e., design of new stationary phases and development of new column configurations, we describe here a variety of column architectures along with their advantages and disadvantages. Newly emerged column technologies in CEC for high speed and high efficiency separation are also discussed. Different analytical platforms of CEC such as pressure-assisted CEC or voltage-assisted micro- high-performance liquid chromatography (HPLC), CEC with different detection techniques, CEC on microchip platforms and multidimensional electrochromatography with their applications in peptide and protein analysis are presented.     

Capillary electrochromatography of biologically relevant flavonoids

Flavonoids were separated utilizing CEC technique. Baseline separation of biologically relevant flavonoids was obtained using a 100 microm ID fused-silica capillary filled with 3 microm Silica-C18 material and an optimized mobile phase comprising of 20 mM Tris-HCl (pH 6.5), ACN and water at a ratio of 10/40/50 v/v/v. Separations were carried out at 25 kV and a column temperature of 25 degrees C. The influence of relevant parameters for the CEC separation, such as buffer concentration, pH, separation voltage, and ACN concentration, was investigated and optimized. Dependencies of the electroendoosmotic flow (EOF) on these parameters and effects on the resolution of the analytes were studied. During analyses the solvents used for dissolving the samples turned out to have significant effects on the separation of flavonoids. The optimized system was then successfully used for the separation of the flavonoids epicatechin, myricetin, quercetin, naringenin, and hesperetin. CEC turned out to be a useful complementary tool for the economic analysis of flavonoids in addition to common HPLC, muHPLC, and CE methodologies. This method can be used for real applications in phytomics.     

Capillary electrochromatography of peptides and proteins

This review surveys the accomplishments in the separation of peptides and proteins by capillary electrochromatography (CEC) over the last decade. A significant number of research articles have been published on this topic since the last review. Peptide and proteins separations have been carried out in all three formats of CEC, i.e., packed bed, continuous bed and open-tubular (OT) format. In addition to electrophoresis, different chromatographic modes have been successfully exploited with the most prevalent being reversed-phase mode followed by ion-exchange. Although many researchers continue to use model proteins and peptides primarily to evaluate the performance of novel stationary phases some researchers have also applied CEC to the analysis of real-life samples. The potential of CEC to yield complementary information and sometimes a superior separation with respect to established techniques, i.e., microbore HPLC and capillary electrophoresis has been demonstrated. Instrumental modifications in order to facilitate coupling of CEC to mass spectrometry have further upgraded the value of CEC for proteomic analysis. Capillaries are still the separation vehicle of choice for most researchers yet the microfluidic platform is gaining momentum, propelled particularly by its potential for multitasking, e.g., performing different chromatographic modes in series.     

Capillary electrochromatography of Triton X-100

Nonionic surfactants such as Triton X-100 (TX-100) are comprised of a mixture of oligomers with a varying degree of length in the ethoxylate chain. The development of chromatographic methods for resolution of the various oligomers of TX-100 is of environmental importance, and can be useful for quality control and characterization in industrial manufacture. Capillary electrochromatography (CEC) is fast becoming a capable separation technique that combines the benefits of both high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE). This report presents a novel CEC method for separation of the various TX-100 oligomers. A comparison of monomeric vs. polymeric stationary phases for separation of TX-100 was conducted. Since the oligomers of TX-100 were better resolved on a monomeric phase as compared to polymeric phase, a systematic mobile phase tuning was performed utilizing a monomeric CEC-C18-3 microm-100 A stationary phase. Various mobile phase parameters such as acetonitrile (ACN) content, Tris concentration, pH, voltage, and temperature were manipulated in order to achieve the optimum separation of oligomers in less than 30 min.     

Analysis of phenolic compounds in extra virgin olive oil by using reversed-phase capillary electrochromatography

In this work, the simultaneous separation of ten phenolic compounds (protocatechuic, p-coumaric, o-coumaric, vanillic, ferulic, caffeic, syringic acids, hydroxytyrosol, tyrosol and oleuropein) in extra virgin olive oils (EVOOs) by isocratic RP CEC is proposed. A CEC method was optimized in order to completely resolve all the analyzed compounds by studying several experimental parameters. The influence of the stationary phase type (C(18) and C(8) modified silica gel), buffer concentration and pH as well as the organic modifier content of the mobile phase on retention factors, selectivity and efficiency were evaluated in details. A capillary column packed with Cogent bidentate C(18) particles for 23 cm and a mobile phase composed by 100 mM ammonium formate buffer pH 3/H(2)O/ACN (5:65:30 v/v/v) allowed the baseline resolution of the compounds under study in less than 35 min setting the applied voltage and temperature at 22 kV and 20 degrees C, respectively. A study, evaluating the intra- and interday precision as well as LOD and LOQ and method linearity was developed in accordance with the analytical procedures for method validation. LODs were in the range of 0.015-2.5 microg/mL, while calibration curves showed a good linearity (r(2) >0.997). The CEC method was applied to the separation and determination of these compounds in EVOO samples after a suitable liquid-liquid extraction procedure. The mean recovery values of the studied compounds ranged between 87 and 99%.     

Capillary electrochromatography of basic compounds using octadecyl-silica stationary phases with an amine-containing mobile phase

The capillary electrochromatographic (CEC) analysis of basic compounds on octadecyl-silica stationary phases (Hypersil ODS and Spherisorb ODS I) was studied. A basic drug (fluvoxamine) and one of its possible impurities were used as test compounds. With an eluent of acetonitrile-phosphate buffer (pH 7.0), the compounds could be baseline-separated; however, broad and tailing peaks were obtained. To minimise detrimental interactions with residual silanol groups, the pH of the mobile phase was lowered to 2.5, but the plate numbers were still quite low (<2.6x10(4) plates/m). Addition of a masking agent (hexylamine or triethylamine) to the mobile phase resulted in much better peak efficiencies (ca. 1x10(5) plates/m). Therefore, the influence of the amine concentration and pH of the mobile phase on the CEC performance (peak width, peak tailing, electroosmotic flow, selectivity) was investigated in detail. Highest efficiencies (2.8x10(5) plates/m) could be obtained with the Spherisorb column, while the Hypersil column offered a better selectivity. Furthermore, the results show that the residual silanol groups are (at least partly) responsible for the separation of the basic compounds and that the amount of injected sample has an unusually large effect on the peak efficiency. The usefulness of the system for impurity profiling was demonstrated with a mixture containing fluvoxamine and its stereoisomer (a possible impurity) at the 0.1% level. The general effectiveness of amine additives in CEC was illustrated by the separation of a mixture of five structurally different basic drugs yielding plate numbers in the 1x10(5)-3x10(5) plates/m range. Comparison with capillary electrophoretic analysis revealed a unique selectivity of the CEC system which is based on both electrophoretic mobility and chromatographic partitioning.     

Capillary electrochromatography with macroporous particles.

The performance of macro-porous particles in capillary electrochromatography is studied. Three reversed-phase stationary phases with pore diameters between 500 A and 4000 A have been tested for separation efficiency and mobile phase velocity. With these stationary phases, a large portion of the total flow appears to be through the pores of particles, thereby increasing the separation efficiency through a further decrease of the flow inhomogeneity and through enhancement of the mass transfer kinetics. The effects of pore size and mobile phase composition on the plate height and mobile phase velocity have been studied. With increasing buffer concentrations and larger pore diameters, higher mobile phase velocities and higher separation efficiencies have been obtained. Columns packed with 7 microns particles containing pores with a diameter of 4000 A generated up to 430,000 theoretical plates/m for retained compounds. Reduced plate heights as low as 0.34 have been observed, clearly demonstrating that a significant portion of the flow is through the pores. For the particles containing 4000 A pores no minimum was observed in the H-u plot up to linear velocities of 3.3 mm/s, suggesting that the separation efficiency is dominated by axial diffusion. On relatively long (72 cm) columns, efficiencies of up to 230,000 theoretical plates/column have been obtained under non-optimal running conditions. On short (8.3 cm) columns fast separations could be performed with approximately 15,000 theoretical plates generated in less than 30 s.     

Beta-eudesmol, a new sesquiterpene component in intact and organized root of chamomile (Chamomilla recutita)

Gas chromatography (GC) and GC-mass spectrometry are used to identify a new sesqiterpene, beta-eudesmol, which seems to be a characteristic essential oil component of the intact and in vitro organized root of chamomile [Chamomilla recutita (L.) Rauschert]. It is identified on three types of stationary phases by GC. The confirmation of identity is carried out by comparison of mass spectra with those reported in the literature and measured from a reference compound. The percentage evaluation of the oil component is made by area normalization, on the basis of three parallel measurements. Among the cultivated and wild chamomile species examined, the wild species from the areas of Szeghalom contain the highest quantity of beta-eudesmol (9.25% in the total essential oil).     

Capillary electrochromatography using polyelectrolyte multilayer coatings

This review covers recent progress in polyelectrolyte multilayer (PEM) coatings applied to analytical separations using open-tubular capillary electrochromatography (OT-CEC). The simple preparation procedure involved in the PEM approach has provided some attractive features over other modes of capillary electrophoresis-based separations including packed column capillary electrochromatography (PC-CEC) and micellar electrokinetic chromatography (MEKC). PEM coatings have been used to alleviate the adsorption of basic analytes, to improve separations, and to improve the stability of the electroosmotic flow. Fundamental aspects of PEM coatings on surfaces and analytical separation platforms are briefly outlined in this review. In addition, applications of PEM coatings to fused-silica capillaries or microchip separation devices for the separation of small achiral or chiral analytes, as well as large biomolecules, are discussed.     

Separation of selected humic degradation compounds by capillary electrochromatography with monolithic and packed columns

The separation of selected lignin/humic substance (HS) degradation compounds by capillary electrochromatography (CEC) with a methacrylate-based monolithic column and a conventional column packed with 5 microm octadecyl silica (ODS) particles is presented. The effects of organic modifier concentration, pH of the mobile phase, ionic strength, applied voltage, and temperature on the separation were investigated to determine the optimal separation conditions. With the increase of pH in the mobile phase, some of analytes start to ionize and both chromatographic partition and electrophoresis can play roles in separation simultaneously. Accordingly, different selectivity from high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE) could be achieved. The performances of both kinds of columns were compared. The results showed that the peaks of compounds obtained on the former column were much wider than those on the latter one, although good separation efficiency of alkylbenzenes could be readily achieved; the most probable reasons for this behavior and method to solve this problem were briefly discussed. The CEC of a soil fulvic acid with a monolithic column produced partly resolved broad bands; by means of nuclear magnetic resonance (NMR) analysis a wide range of oxygen derived aromatic substitution patterns was found with prominent contributions from phenolic and carboxylic groups.     

Capillary electrophoresis and electrochromatography of pesticides and metabolites

Synthetic pesticides are important chemicals since they are widely used to control many types of weeds, insects, and other pests in a wide variety of agricultural and nonagricultural settings. This review article is aimed at describing the recent progress made in capillary electrophoresis (CE) and capillary electrochromatography (CEC) of pesticides and metabolites. The various electrophoretic systems and detection schemes that were introduced during the period extending from the second half of 1999 to the first half of 2001 for the CE and CEC of pesticides are discussed. Also included in this review article are the various approaches for trace enrichment that are involved in the analysis of dilute pesticide samples.     

Capillary electrochromatography of proteins with polymer-based strong-cation-exchanger microspheres

Monodisperse poly(glycidyl methacrylate-divinylbenzene) microspheres were functionalized with propyl sulfonic acid moieties to obtain beads negatively charged in a wide pH range. They were packed into fused-silica capillary of 50 micro, I.D. in order to separate proteins by capillary electrochromatography (CEC). Baseline separation of four basic proteins as well as three cytochrome c variants with an average column efficiency of 60,000 theoretical plates was obtained under isocratic elution conditions. The high efficiency is attributed to the uniformity of the column packing and the hydrophilic surface coverage of the polymer beads derived from the functionalization process. The effect of pH and salt concentration on protein separations was investigated and the results showed that the CEC separation mechanism is the combination of chromatographic retention and electrophoretic migration. Moreover, the column packed with the strongly acidic poly(glycidyl methacrylate-divinylbenzene) beads was also suitable for protein separations by micro-HPLC with a salt gradient. The comparison between the two kinds of elution modes shows that the column described here exhibited higher peak efficiency with isocratic elution in CEC than with gradient elution in micro-HPLC.     

Capillary electrophoresis and electrochromatography of pesticides and metabolites

Synthetic pesticides are important chemicals since they are widely used to control many types of weeds, insects and other pests in a wide variety of agricultural and nonagricultural settings. This review article is aimed at describing the recent progress made in capillary electrophoresis (CE) and capillary electrochromatography (CEC) of pesticides and their metabolites. The various electrophoretic systems and detection schemes that have been introduced so far for the CE and CEC of pesticides are discussed. Also included in this review article are the various approaches for trace enrichment that are involved in the analysis of dilute pesticide samples.     

Capillary electrophoresis and capillary electrochromatography of organic pollutants

Capillary electrophoresis (CE) has a unique capability for separation of analytes of environmental concern, particularly those that are more polar and ionic, based on the complementary separation principle of electrophoresis. In the past few years, CE has been selectively used to analyze various classes of compounds having current or potential environmental relevance. This review outlines the current status of CE for the determination of environmental pollutants, based predominantly on research results published from the beginning of 1997 to early 1999. Covered are environmental pollutants of all types except pesticides and inorganics. Certain naturally produced toxins are also covered because of their significant impacts upon human health and the environment. CE methods, as with all methods, must be judged on their ability to provide approaches that are reliable, sensitive, selective, and rapid, while meeting "green chemistry" initiatives for pollution prevention. We also compare CE methods to benchmark environmental techniques involving gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS), and high performance liquid chromatography (HPLC).