Advances and Challenges in the Analysis of Boswellic Acids by Separation Methods.

resin is an exudate from the cut bark of trees. The main constituents of pharmacological interest are boswellic acids (pentacyclic triterpenoids), namely α-boswellic acid, β-boswellic acid, 3--acetyl-α-boswellic acid, 3-acetyl-β-boswellic acid, 11-keto-β-boswellic acid, and 3--acetyl-11-keto-β-boswellic acid. Nowadays, dietary supplements with extract are used in the treatment of inflammatory joint diseases.

Coupling of chiral and achiral stationary phases in supercritical fluid chromatography: Evaluating and improving retention prediction.

Isomers and stereoisomers are always challenging to separate. Column coupling may provide improved chromatographic selectivity, necessary for the separation of the compounds with similar chemical and structural properties. The relatively low viscosity of supercritical fluids, used as mobile phases allows for the coupling of several columns in series in supercritical fluid chromatography (SFC), without exceeding the pressure limits of the system.

Development of a capillary electrophoresis method for the separation of flavonolignans in silymarin complex.

CE method for the baseline separation of structurally similar flavonolignans silybin A, silybin B, isosilybin A, isosilybin B, silychristin, silydianin, and their precursor taxifolin in silymarin complex has been developed and validated. The optimized background electrolyte was 100 mmol/L boric acid (pH 9.0) containing 5 mmol/L heptakis(2,3,6-tri-O-methyl)-β-CD and 10% (v/v) of methanol.

Stability study of α-bromophenylacetic acid: Does it represent an appropriate model analyte for chiral separations?

The stability of α-bromophenylacetic acid (BPAA) in 50% aqueous methanol solution has been tested. CE in different running buffers was used to separate BPAA from the decomposition reaction products α-hydroxyphenylacetic (mandelic) acid and α-methoxyphenylacetic acid. Suitable CE separation of all three compounds and other product, bromide, was achieved in 60 mmol/L formate buffer (pH 3.

In-line molecularly imprinted polymer solid phase extraction-capillary electrophoresis coupled with tandem mass spectrometry for the determination of patulin in apple-based food.

We present a simple and sensitive method for the determination of patulin at µg·kg level in apple-based products. Our method relies on the application of an in-line molecularly imprinted polymer solid-phase extraction microcartridge in capillary electrophoresis coupled with mass spectrometry. Capillary zone electrophoresis method has been developed and parameters affecting the in-line process have been carefully optimized.

Determination of Sudan dyes in chili products by micellar electrokinetic chromatography-MS/MS using a volatile surfactant.

A new MEKC-MS/MS method was developed for the determination of four Sudan dyes in chili products. The separation and MS detection conditions were optimized to achieve fast, efficient, selective, and sensitive determination of Sudan I, Sudan II, Sudan III, and Sudan IV dyes. The target compounds were extracted from chili samples with acetonitrile and cleaned by freeze-out.

Cyclodextrins as Chiral Selectors in Capillary Electrophoresis Enantioseparations.

Due to their structural variability and their commercial availability, cyclodextrins are the most frequently used chiral selectors in capillary electrophoresis. A variety of migration modes can be realized depending on the characteristics of the cyclodextrins and the analytes. The basic considerations regarding the development of a chiral CE method employing cyclodextrins as chiral selectors are briefly discussed.

Development of micellar electrokinetic chromatography method for the determination of three defined impurities in indomethacin.

A micellar electrokinetic chromatography method for the determination of indomethacin impurities (4-chlorobenzoic acid, 5-methoxy-2-methyl-3-indoleacetic acid, and 3,4-dichloroindomethacin) has been developed. A 64.5/56-cm fused silica 50 μm id capillary with extended light path (150 μm id) detection window was used.

Stereospecific electrophoretically mediated microanalysis assay for methionine sulfoxide reductase enzymes.

An electrophoretically mediated microanalysis assay (EMMA) for the determination of the stereoselective reduction of L-methionine sulfoxide diastereomers by methionine sulfoxide reductase enzymes was developed using fluorenylmethyloxycarbonyl (Fmoc)-L-methionine sulfoxide as substrate. The separation of the diastereomers of Fmoc-L-methionine sulfoxide and the product Fmoc-L-methionine was achieved in a successive multiple ionic-polymer layer-coated capillary using a 50 mM Tris buffer, pH 8.0, containing 30 mM sodium dodecyl sulfate as background electrolyte and an applied voltage of 25 kV.

Stereospecific micellar electrokinetic chromatography assay of methionine sulfoxide reductase activity employing a multiple layer coated capillary.

A micellar electrokinetic chromatography method for the analysis of the l-methionine sulfoxide diastereomers employing a successive multiple ionic-polymer layer coated fused-silica capillary was developed and validated in order to investigate the stereospecificity of methionine sulfoxide reductases. The capillary coating consisted of a first layer of hexadimethrine and a second layer of dextran sulfate providing a stable strong cathodic EOF and consequently highly repeatable analyte migration times. The methionine sulfoxide diastereomers, methionine as product as well as β-alanine as internal standard were derivatized by dabsyl chloride and separated using a 35 mM sodium phosphate buffer, pH 8.

Enantioseparations by capillary electrophoresis using cyclodextrins as chiral selectors.

Due to their commercial availability, cyclodextrins are the most frequently used chiral selectors in capillary electrophoresis as documented by the numerous publications in the field. A variety of migration modes can be realized depending on the characteristics of the cyclodextrins and the analytes. The basic considerations regarding the development of a chiral CE method employing cyclodextrins as chiral selectors are briefly discussed.

Recent advances in electrodriven enantioseparations.

Capillary electromigration techniques have developed into significant analytical separation tools especially for enantioseparations. While CE can be considered a mature technique as documented by its wide applications, CEC is still in a developmental state despite many research efforts. The success of stereospecific CE separation methods is due to the high specificity and flexibility of the technique as well as the availability of many types of chiral selectors.

Determination of carbethopendecinium bromide in eye drops by capillary electrophoresis with capacitively coupled contactless conductivity detection.

Antiseptic agent carbethopendecinium bromide (septonex) was determined by capillary electrophoresis with capacitively coupled contactless conductivity detection. Optimal separation of this quaternary ammonium ion was achieved in BGE of pH 7.0 containing 30 mM 2-(N-morpholino)ethanesulfonic acid, 12.

Determination of muscle relaxants pancuronium and vecuronium bromide by capillary electrophoresis with capacitively coupled contactless conductivity detection.

A novel capillary electrophoretic method for the separation of pancuronium (PM) and vecuronium (VM) ions utilizing capacitively coupled contactless conductivity detection was devised and validated. The separation was carried out in bare fused-silica capillaries (50 μm id, 75/45 cm) at 25°C. Optimal BGE was 50 mM borate buffer of pH 9.

Fast assay of glucosamine in pharmaceuticals and nutraceuticals by capillary zone electrophoresis with contactless conductivity detection.

A novel capillary electrophoresis (CE) method with contactless conductivity detection suitable for the determination of glucosamine (GlAm) and K(+) in pharmaceuticals was devised. Under the optimum conditions (aqueous 30 mM acetate buffer of pH 5.2 as the background electrolyte; voltage 30 kV; 25 degrees C), GlAm (migrating as glucosaminium cation) was well separated from K(+) that could occur in the dosage forms as excipient.

Tungstate as complex-forming reagent facilitating separation of selected polyphenols by capillary electrophoresis and its comparison with borate.

A novel electrophoretic BGE containing tungstate as complex-forming reagent is suitable for the separation of polyphenols. Similar to molybdate-containing BGE reported earlier (cf. M.

Development and validation of a capillary electrophoresis method for the simultaneous determination of impurities of escitalopram including the R-enantiomer.

A stereospecific capillary electrophoresis assay for the simultaneous determination of related substances and the enantiomeric purity of escitalopram was developed by a central composite face-centered factorial design and subsequently validated. Separations were carried out in a 50 microm, 47/40 cm fused-silica capillary. The optimized conditions included 20mM phosphate buffer, pH 2.

Recent trends in the determination of polyphenols by electromigration methods.

An overview mapping recent trends in the determination of polyphenols of natural origin (mostly flavonoids) and their synthetic derivatives by electromigration methods is presented. The overview (covering the period of the recent 5 years and comprising 61 references) is focused on capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC) with various detection methods. Techniques comprising on-line pre-separation such as isotachophoresis (ITP)-CZE and flow-injection-CZE, chiral separations and CZE evaluation of antioxidation activity are also discussed.