Showing papers in "Chromatographia in 1999"
TL;DR: A liquid-solid extraction and purification procedure (LSE) was developed to identify and quantify polyphenols in the leaf tissue of Myrtus communis L. as mentioned in this paper, which is the first report on the occurrence of galloyl-derivatives of catechin and gallo-catechin.
Abstract: A liquid-solid extraction and purification procedure (LSE) was developed to identify and quantify polyphenols in the leaf tissue ofMyrtus communis L. Identification and quantitation of individual compounds was performed using HPTLC, HPLC-DAD and HPLC-MS analysis. Leaves ofMyrtus communis L. contain small amounts of phenolic acids (caffeic, ellagic and gallic acids) and quercetin derivatives (quercetin 3-O-galactoside and quercetin 3-O-rhamnoside), whereas catechin derivatives (epigallocatechin, epigallocatechin 3-O-gallate, epicatechin 3-O-gallate) and myricetin derivatives (myricetin 3-O-galactoside, myricetin 3-O-rhamnoside) are present in large amounts. This is the first report on the occurrence of galloyl-derivatives of catechin and gallo-catechin inMyrtus communis L. leaves.
102 citations
TL;DR: In this article, the column performance of the hypercrosslinked polystyrene was found to be acceptable, with reduced plate height increasing very slowly as the linear velocity of the mobile phase increased to high values (up to 20-45 cm min−1).
Abstract: The mechanical rigidity, swelling properties, adsorption selectivity, and chromatographic performance of hypercrosslinked polystyrene (mainly MN-200 or Purosep-200; Purolite, UK) have been studied to evaluate the use of the material as a stationary phase for reversed-phase high-performance liquid chromatography (RPHPLC). By use of inverse size-exclusion chromatography (SEC) this adsorbent, with a high specific surface area of 1500 m2 g−1 was found to have a biporous structure with micropores of ca 1–2 nm and macropores ca 100 nm in diameter. The polymer does not change its volume significantly on changing water for organic solvents. The retention increments for methylene and phenyl groups were calculated and indicated that the mechanism of retention on the hypercrosslinked polystyrene involves π-π interactions and strong hydrophobic interactions. The column performance of the hypercrosslinked polystyrene was found to be acceptable, with reduced plate height increasing very slowly as the linear velocity of the mobile phase increased to high values (up to 20–45 cm min−1). Columns containing hypercrosslinked polystyrene were evaluated for the separation of phenols, dialkyl phthalates, and polyaromatic compounds. On-column preconcentration of trace organic compounds from aqueous media is possible. With smaller particles of hypercrosslinked polystyrene becoming available, this material can be regarded as an alternative to alkylsilica as a hydrolytically stable column-packing material for RPHPLC.
96 citations
TL;DR: In this paper, a 2 μL drop of organic solvent is suspended on the tip of a microsyringe in a stirred aqueous sample solution. After the prescribed extraction time the drop is drawn back into the syringe.
Abstract: This paper is a preliminary report on a fast method for the extraction of organochlorine pesticides from river water which is inexpensive, fast and has little to no waste that has been developed. Pesticide extraction was achieved using the relatively new technique of solvent microextraction. In this technique a 2 μL drop of organic solvent is suspended on the tip of a microsyringe in a stirred aqueous sample solution. After the prescribed extraction time the drop is drawn back into the syringe. The syringe is then removed and the contents are injected into a gas chromatograph for analysis. Extraction of eleven organochlorinated pesticides from aqueous solutions with concentrations down to 1 ng mL−1 was achieved. The developed procedure was tested as a screening method for pesticides with spiked river water samples and was found to be linear over the concentration range of interest.
82 citations
TL;DR: The partial filling technique (PFT) in capillary electrophoresis (CE) is an efficient system where, only 50–800 nanolitres of a chiral selector solution needs to be added to each run.
Abstract: The partial filling technique (PFT) in capillary electrophoresis (CE) is an efficient system where, only 50–800 nanolitres of a chiral selector solution needs to be added to each run. PFT is especially applicable when these additives to the background electrolyte (BGE) are expensive or absorb UV light. The selector dissolved in the BGE is applied to the capillary as a plug, shorter than the effective length of the capillary, prior to application of the analyte. During the run both ends of the capillary are connected to the BGE. The applied plug and the analyte may move in opposite directions or in the same direction at different velocities depending on their electrophoretic mobilities. Thus the final plug length is either longer or shorter than the original length. The technique has been successfully applied in a number of studies including enantiomeric separation with a variety of selectors, and for the determination of conditional association constants.
76 citations
TL;DR: In this article, a liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS) was developed for the analysis of mutagenic heterocyclic amines.
Abstract: In-tube solid-phase microextraction (in-tube SPME) coupled with liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS) was developed for the analysis of mutagenic heterocyclic amines. LC/MS analyses of heterocyclic amines were initially performed by liquid injection onto a LC column. All heterocyclic amines tested in this study gave very simple ESI mass spectra and strong signals corresponding to [M+H]+ were observed for all heterocyclic amines except for Glu-P-1 and Glu-P-2 ([M+NH4−H2O]+ ions were observed from these amines). All heterocyclic amines were well separated with a Supelcosil LC-CN column except for AαC and Glu-P-2 which consistently co-eluted. In order to optimize the extraction of heterocyclic amines several in-tube SPME parameters were examined using five representative compounds. The optimum extraction conditions were as follows: 10 aspirate/dispense steps of 30 μL of sample in 100 mM Tris-HCl (pH 8.5) at the flow the flow rate of 100 μL min−1 with Omegawax 250 capillary column. The heterocyclic amines extracted by the capillary column were easily desorbed by aspiration of 30μL of methanol prior to injection, and carryover of heterocyclic amine was not observed. The calibration curves obtained from the ratios of heterocyclic amine area counts against that of 4,7,8-TriMeIQx as an internal standard were linear in the range of 5 to 200 ng mL−1, with correlation coefficients above 0.9976 (n=18). The detection limits (S/N=3) were 0.2–3.1 ng mL−1. This method was successfully applied to the analysis of food samples.
69 citations
TL;DR: A molecularly imprinted polymer has been developed which subsequently demonstrated an ability to selectively retain darifenacin (UK-88, 525-S) from aqueous acetonitrile when used as a stationary phase in HPLC columns and as a packing in solid phase extraction cartridges.
Abstract: A molecularly imprinted polymer has been developed which subsequently demonstrated an ability to selectively retain darifenacin (UK-88, 525-S) from aqueous acetonitrile when used as a stationary phase in HPLC columns and as a packing in solid-phase extraction cartridges.
63 citations
TL;DR: In this article, an Artificial Neural Network (ANN) was used to model retention times of anions in nonsuppressed and suppressed ion chromatography (IC) using a range of eluents and stationary phases, with the results being compared to those obtained using mathematical retention models.
Abstract: An Artificial Neural Network (ANN) was investigated as a method to model retention times of anions in nonsuppressed and suppressed ion chromatography (IC) using a range of eluents and stationary phases, with the results being compared to those obtained using mathematical retention models. The optimal ANN architecture was determined for six specific IC cases of increasing complexity. Analysis of the retention times predicted using the ANN and those predicted by the mathematical models showed that the ANN approach yielded superior performance in all of the above cases. The use of a limited training data set configured in a central composite experimental design was suitable for application of the ANN to non-suppressed IC but was not applicable to suppressed IC, for which a more extensive training data set was necessary.
60 citations
TL;DR: In this paper, a high-performance liquid chromatographic method was developed for the simultaneous quantitative determination of resorcinol and 1-naphthol in hair tonic and haircolor products.
Abstract: A high-performance liquid chromatographic method has been developed for the simultaneous quantitative determination of resorcinol and 1-naphthol in hair tonic and haircolor products. The two compounds could be separated on a μBondapak C18 column by elution with 50∶50 (v/v) methanol-water as mobile phase. The retention times of resorcinol and 1-naphthol were 2.5 and 7.0 min, respectively. Seven dye intermediates could be analyzed within 12 min without any interference with the peaks of resorcinol and 1-naphthol from other cosmetic ingredients present in the haircolor liquid or cream. The results obtained were in good agreement with those obtained by a spectrophotometric method.
52 citations
TL;DR: In this paper, a combined HPLC-NMR-MS system was used to provide a more comprehensive analysis of the ecdysteroids present in the extract than HPLC alone.
Abstract: HPLC coupled in parallel to nuclear magnetic resonance (NMR) and mass spectrometry (MS) has been used to obtain1H NMR and mass spectra of a number of ecdysteroids present in an extract of the plantSilene otites. Reversed phase gradient chromatography was performed using a D20-acetonitrile-based solvent system. NMR and mass spectra were obtained for integristerone A, 20-hydroxyecdysone, 2-deoxy-20-hydroxyecdysone and 2-deoxyecdysone to provide structural confirmation using continuous and stopped flow HPLC-NMR. The combined HPLC-NMR-MS system described here provided a more comprehensive analysis of the ecdysteroids present in the extract than HPLC-NMR alone.
51 citations
TL;DR: This report clearly shows that MEEKC can be widely applied to a range of compounds and is especially useful for complex mixtures containing solutes with varying charge and hydrophobicity.
Abstract: Microemulsion Electrokinetic Chromatography (MEEKC) has previously been reported to be useful for the separation of a range of hydrophobic solutes. The previous reports had tended to show relatively long separation times. In this report the separation and operation conditions were optimized and a method was successfully employed in a range of novel applications. High efficiencies, rapid separations and high repeatability were demonstrated. The applications developed included a range of both neutral and charged compounds. Both water-soluble and water-insoluble compounds were also well separated. The novel applications developed included analysis of basic drugs, various aromatic acids, a range of neutral aromatics, profiling of ink components, direct injection of urine for profiling purposes and the analysis of a range of amino acids and their derivatives. The method could also be used for hydrophobicity measurements of the resolved solutes based upon their migration times. This report clearly shows that MEEKC can be widely applied to a range of compounds and is especially useful for complex mixtures containing solutes with varying charge and hydrophobicity.
50 citations
TL;DR: In this paper, a subcritical water extraction (SWE) method was proposed for the extraction of eucalyptus essential oil, which was compared with another based on, hydro-distillation a conventional extraction procedure.
Abstract: A method based on subcritical-water extraction (SWE) before detection and identification by GC-FID and GC-MS, respectively, has been developed for the isolation of eucalyptus essential oil. The proposed method has been compared with another based on, hydro-distillation a conventional extraction procedure. Fresh cucalyptus leaves (4g) were extracted with water at 50 bar, 150°C and 2 mL min−1 for 20 min. Hydro-distillation was performed on the same amount of leaves with 360 mL water for 3 h. After each extraction the compounds were removed from the aqueous extract by a single extraction with hexane (5 mL), detected by GC-FID, and identified by electron impact (EI) MS. The SWE-based method is clearly quicker and more efficient than the hydrodistillation-based method, because yields from the former for 11 of the 13 major compounds in the extract are higher after 20-min extraction than after hydrodistillation for 3h. This enables substantial cost savings of both energy and raw material.
TL;DR: In this article, the relative order of elution of a series of sulfonamides on a polystyrene-divinyl benzene column was determined at pH 3, 7 and 11.
Abstract: Inorganic buffers have been used to control the pH of a superheated water eluent for reversed-phase liquid chromatography. Using a temperature gradient from 70–190 °C, the relative order of elution of a series of sulfonamides on a polystyrene-divinyl benzene column was determined at pH 3, 7 and 11. The separations were compared with conventional reversed-phase separations on polymer and ODS-bonded silica columns. The apparent pK
a values of selected sulfonamides at elevated temperatures were determined from their retention factors across in a range of superheated buffers and the values were compared to those reported at room temperature.
TL;DR: A screening method using nonaqueous capillary electrophoresis (NACE) has been developed for purity analysis of pyridinyl-methyl-sulfinyl-benzimidazoles (PMSB).
Abstract: A screening method using nonaqueous capillary electrophoresis (NACE) has been developed for purity analysis of pyridinyl-methyl-sulfinyl-benzimidazoles (PMSB). Eight different polar organic solvents were tested as background electrolytes.N-Methylformamide (NMF) was found to have the best properties in respect of both electrophoretic behavior and high solubility of five different model compounds. Optimization of the CE separation with regard to the effects of addition of various electrolyte modifiers is reported. An additional feature of amide solvents, rarely utilized in CE, is their intrinsic basic nature; this is of particular interest for analysis of compounds such as the PMSB, the degradation of which is acid-catalyzed. It is shown here that these compounds are stable at room temperature for weeks in NMF solution. Results from quantitative application of the NACE method were highly precise (typically 1.8%RSD for normalized peak area); linearity was good and detection limit in drug purity determination was low (∼0.05 area % relative to the drug compound).
TL;DR: An HPLC method with fluorescence detection has been developed for the determination of fluoxetine and its main metabolite norfluoxetines in human plasma as mentioned in this paper, which uses 200 μL plasma and recovery is good for both analytes.
Abstract: An HPLC method with fluorescence detection has been developed for the determination of fluoxetine and its main metabolite norfluoxetine in human plasma. Pretreatment of the biological samples by liquid-liquid extraction was used to improve the sensitivity of a previously published SPE procedure. The method uses 200 μL plasma and recovery is good for both analytes. On a C8 column with a mixture of perchlorate buffer and acetonitrile as mobile phase fluoxetine, norfluoxetine and the internal standard (paroxetine) were eluted in less than 9 min, without interference from the biological matrix. Response for both analytes was linearly dependent on concentration over the range 2.5–500 ng mL−1, and repeatability (RSD%) was <4%. The limit of detection was 1 ng mL−1 for both fluoxetines. Application to plasma samples from depressed patients treated with fluoxetine gave good results. There was no interference from other common CNS drugs. This method seems to be a useful tool for clinical monitoring, because it requires small plasma samples and is highly sensitive and highly selective.
TL;DR: In this article, the dependence of electroosmotic flow on particle diameter and the influence of the mobile phase composition, i.e. organic modifier content, pH of buffer solution and concentration of buffer salt, on the magnitude of the EO flow velocity has been investigated.
Abstract: Reversed-phase stationary phases based on porous silica beads in the range 0.2–3 μm have been prepared to study the dependency of electroosmotic flow (EOF) on particle diameter. Additionally, the influence of the mobile phase composition, i.e. organic modifier content, pH of buffer solution and concentration of buffer salt, on the magnitude of the electroosmotic flow velocity has been investigated. To perform separations in an aqueous acidic mobile-phase, mixed mode stationary phases containing both alkyl chains and strong cationexchange groups have been applied.
TL;DR: In this paper, the development and comparison of two analytical methods (HPLC in reversed phase and normal phase mode and GC) for the determination of six major lactones in P methysticum is described.
Abstract: The development and comparison of two analytical methods (HPLC in reversed phase and normal phase mode and GC) for the determination of six major lactones inP methysticum is described in this paper By all methods, a satisfying separation of these compounds could be achieved Each method shows distinct advantages to previously published ones, regarding separation quality, time or conditions Several kava samples were analyzed by these new or modified methods, and the qualitative and quantitative results obtained were comparable Primary differences in separation times and detection limits were observed, so that each method might be preferable, depending on the requirements
TL;DR: In this article, a micellar electrokinetic chromatography has been used for the simultaneous separation of 16 positional and optical isomers of the tryptophan family, and the best result was obtained by using SDS.
Abstract: Ligand-exchange micellar electrokinetic chromatography has been used for the simultaneous separation of 16 positional and optical isomers of the tryptophan family The Cu(II) complex with L-hydroxyproline was used as the chiral selector Two groups of anionic surfactant, linear alkylbenzenesulfonates (LAS) and straight-chain alkyl sulfates such as sodiumn-decyl sulfate (SDeS), sodium dodecyl sulfate (SDS) and sodiumn-tetradecyl sulfate (STS), were used for simultaneous separation The best result was obtained by use of SDS The influence of SDS concentration and of pH on the separation was investigated The separation behavior in the absence of the Cu(II) complex with L-hydroxyproline was also examined Use of organic modifiers causes the resolution to decrease Relationships between the logarithm of the octanol-water partition coefficient (logP
OW) and resolution, and between logP
OW and migration time are discussed
TL;DR: In this article, the hypericin and pseudohypericin content of both Hyperici Herba and Hypericum perforatum L. dried flowers were measured by two techniques, TLC-densitometry with fluorescence detection and reversed-phase HPLC-DAD (diode-array detection).
Abstract: Hypericum perforatum L. is a spontaneous perennial herbaceous plant, widely distributed in Europe, Asia, Northern Africa, and North America. The dried flowers or dried aerial parts are used to prepare the drug Hyperici Herba or St. John's Wort. Nowadays this drug is largely used as a natural antidepressant; hypericin and hypericin-like substances are considered the main active ingredients. In this work the hypericin and pseudohypericin content of hydroalcoholic extracts both of Hyperici Herba and ofHypericum perforatum L. dried flowers were measured by two techniques, TLC-densitometry with fluorescence detection and reversed-phase HPLC-DAD (diode-array detection). The quantitative data obtained by applying these techniques were compared and the identification of the main flavonoid constituents was performed by HPLC-DAD for characterization of the extracts.
TL;DR: In this paper, the separation and determination of β-(3,4-dihydroxyphenyl) lactic acid, protocatechuic acid, and protocatechic aldehyde in RadixSlviae Miltiorrhizae injection were investigated by capillary zone electrophoresis.
Abstract: The separation and determination of β-(3,4-dihydroxyphenyl) lactic acid, protocatechuic acid and protocatechuic aldehyde in RadixSlviae Miltiorrhizae injection were investigated by capillary zone electrophoresis. With boric acid (200 mmol L−1) adjusted to pH 8.11 as a background electrolyte, 28 kV applied voltage and 30°C thermostating temperature, complete separation of β-(3,4-dihydroxyphenyl)lactic acid, protocatechuic acid and protocatechuic aldehyde was readily achieved within 9 min. Results indicate that capillary electrophoresis promises to be applicable to quality control of radixSalviae Miltiorrhiza injection.
TL;DR: In this paper, Ochratoxin A (OTA) was detected in German beers by high-performance liquid chromatography with fluorescence detection, and the results showed that OTA levels in the range of 0.1-0.2 μg L−1 were found in 9 beer samples, 21 samples contained trace amounts of OTA, and in 5 samples no OTA was detectable.
Abstract: Ochratoxin A (OTA) is a nephrotoxic and nephrocacinogenic mycotoxin commonly produced by several ubiquitousAspergillus andPenicillium species. OTA is found predominantly in cereals and derived products, and therefore OTA may be transferred into beer from contaminated grain. Thirty-five samples of German beers were analyzed: OTA was extracted with toluene and purified by solid phase extraction using silica cartridges. OTA was determined by high-performance liquid chromatography with fluorescence detection. Since of fluorescence detection is not specific in this instance, the beer samples were also analyzed by high-performance liquid chromatography electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS). OTA levels in the range of 0.1–0.2 μg L−1 were found in 9 beer samples, 21 samples contained trace amounts of OTA (<0.1 μg L−1) and in 5 samples no OTA was detectable.
TL;DR: In this paper, the potential of nonaqueous capillary electrophoresis for the separation of structurally similar tropane alkaloids was investigated for root cultures of Datura candida x D. aurea.
Abstract: The potential of nonaqueous capillary electrophoresis has been investigated for the separation of structurally similar tropane alkaloids. The effects of the organic solvent and of electrolyte composition on separation selectivity, migration times, and efficiency are described. The addition of trifluoroacetic acid to the separation buffer was found beneficial for manipulation of the order of migration of the two positional isomers littorine and hyoscyamine. Replicate injections under nonaqueous conditions gave migration time and peak area data of excellent precision. The application of the optimized conditions to the analysis of hyoscyamine and scopolamine in genetically transformed root cultures ofDatura candida x D. aurea is presented.
TL;DR: Impurity profiling of ecstacy and amphetamine seizures was accomplished by solid-phase microextraction (SPME) combined with capillary gas chromatography (GC) with complex impurity profiles obtained by SPME providing a high information content.
Abstract: Impurity profiling of ecstacy and amphetamine seizures was accomplished by solid-phase microextraction (SPME) combined with capillary gas chromatography (GC). Samples were dissolved in 0.1 M aqueous acetate buffer (pH 5.0) as the only manual operation and subsequently subjected to SPME-GC. Ecstacy tablets were analyzed by head-space SPME to avoid contamination of SPME fibers with insoluble tablet components, while illicit amphetamine powders were exposed to immersed SPME. A SPME fiber of polydimethylsiloxane-divinylbenzene was found to provide excellent extraction of both polar and non-polar impurities. For both illicit ecstacy and amphetamine, complex impurity profiles were obtained by SPME providing a high information content. For ecstacy, profiles (relative peak areas) were repeatable within 2.2 to 12.6% RSD (n=6) while similar data on amphetamine varied between 2.0 and 10.9% RSD (n=6). No carry-over was observed although each fiber was used for 50 to 100 extractions.
TL;DR: In this paper, a new method is proposed for preparation of ap-tert-butyl-calix[4]arene-bonded silica stationary phase, which is attached to silica gel via the silane coupling reagent γ-(ethylenediamino)-propyl-triethoxyl-silane.
Abstract: A new method is proposed for preparation of ap-tert-butyl-calix[4]arene-bonded silica stationary phase. The chemically modifiedp-tert-butyl-calix[4]arene is attached to silica gel via the silane coupling reagent γ-(ethylenediamino)-propyl-triethoxyl-silane. The bonded phase has been characterized by29Si and13C cross polarization/magic angle spinning solid-state nuclear magnetic spectrometry. The retention behavior of polycyclic aromatic hydrocarbons (PAHs), nucleosides and bases has been investigated on the bonded phase in the reversed-phase mode.
TL;DR: In this article, a new packing based on a magnesia-zirconia composite was synthesized as rigid microparticles (4-6 μm) by a sol-gel process.
Abstract: A new packing based on a magnesia-zirconia composite was synthesized as rigid microparticles (4–6 μm) by a sol-gel process. The magnesia-zirconia composite exhibits a larger specific surface area, larger specific pore volume, better pore connectivity and more uniform pore size distribution than pure zirconia prepared under the same conditions. The chromatographic performance of magnesia-zirconia and zirconia packings in normalphase HPLC was evaluated using binary mobile phases (dichloromethane/cyclohexane, chloroform/cyclohexane and isopropanol/cyclohexane) and acidic, neutral and basic compounds as solutes. The efficiency of columns packed with the magnesia-zirconia composite was higher than that of zirconia.
TL;DR: For analysis of opioids as standards or in plasma extracts by binary capillary electrophoresis with ethylene glycol, the data presented unambiguously demonstrate that the water plug initially inserted at the column inlet is essential for establishing a steady current during separation, and thus the highest reproducibility.
Abstract: Strategies to improve the sensitivity of drug monitoring in microliter amounts of biological fluids by capillary electrokinetic methods are currently being explored in our laboratory. Head-column field-amplified sample stacking is the most effective method of sensitivity enhancement—this approach is robust and highly reproducible when applied correctly. For analysis of opioids as standards or in plasma extracts by binary capillary electrophoresis with ethylene glycol, the data presented in this work unambiguously demonstrate that the water plug initially inserted at the column inlet is essential for establishing a steady current during separation, and thus the highest reproducibility. Internal calibration shows thatRSD imprecision values otherwise up to approximately 30% are reduced to values significantly below 10%. The water plug also results in higher detector responses at elevated solute levels (≥100 ng mL−1) and leads to increased sensitivity when the sample (standards and extracts of body fluids) is dissolved in water. The water plug does not, however, furnish higher sensitivity in the analysis of opioids as standards or in plasma extracts that are prepared in the optimized sample solvent or buffer. The optimum length of the water plug cannot, furthermore, be obtained merely by dipping the capillary inlet into water (insertion of water by capillary action). The water zone obtained in this way must be elongated by approximately 0.6 mm by deliberate hydrodynamic introduction of additional water from a different vial. These head-column field-amplified sample-stacking conditions are shown in operation on two different commercial instruments. As an illustration, data are presented depicting the analysis of dihydrocodeine and nordihydrocodeine in plasma and urine specimens of individuals to which dihydrocodeine was administered.
TL;DR: In this article, a GC-MS method was developed to assess individual exposure to monoaromatic hydrocarbons (benzene, toluene, ethyl benzene and xylenes-BTEX) in biological fluids, using headspace sampling of BTEX with a 75 μm Carboxenpolydimethylsiloxane (PDMS) fiber.
Abstract: To assess individual exposure to monoaromatic hydrocarbons (benzene, toluene, ethylbenzene and xylenes-BTEX) in biological fluids, a GC-MS method was developed. Headspace sampling of BTEX was by solidphase microextraction (SPME) with a 75 μm Carboxenpolydimethylsiloxane (PDMS) fiber. Linearity was established for concentrations up to 50 μg L−1. Detection limits, calculated both in human blood and urine, ranged 5–10 ng L−1. Repeatability was in the range 6.5–9.2% for all compounds. The method was applied to the evaluation of the internal dose of BTEX in a group of cyclists running for 2 h within city routes. Benzene and toluene in blood, and toluene and xylenes in urine significantly increased after exercise as compared to prerun values, such changes being consistent with airborne concentrations. The combination of SPME with GC-MS seems to represent an appropriate analytical approach to detect changes in the concentration of monoaromatic hydrocarbons in biological media resulting from exposure to environmental pollution.
TL;DR: Coupling of capillary electrophoresis (CE) with nuclear magnetic resonance (NMR) spectroscopy has been achieved by use of a recently developed capillary NMR interface for the analysis of synthetic nucleic acids.
Abstract: Coupling of capillary electrophoresis (CE) with nuclear magnetic resonance (NMR) spectroscopy has been achieved by use of a recently developed capillary NMR interface. The technique has been used for the analysis of synthetic nucleic acids. A crude adenosine dinucleotide synthesized by solid-phase chemistry has been investigated by continuous-flow CE-NMR. The combination of the separation technique and NMR spectroscopy proved well suited to identification of the main components, and to detection of by-products of the synthesis of the nucleotide. Two-dimensional CE-NMR spectra were also acquired in the stopped-flow mode and the TOCSY NMR spectrum thus acquired afforded confirmatory evidence for the structure of the adenosine dinucleotide. All experiments were performed in fully deuterated solvents and using nanoliter amounts of the dinucleotide sample.
TL;DR: Molecular biochromatography with human serum albumin immobilized on silica as stationary phase was used to screen and analyse the bioactive compounds in the typical Chinese medicine of Angelica sinensis (Oliv.) Diels.
Abstract: A novel strategy for the screening and analysis of biologically active compounds in traditional Chinese medicine by molecular biochromatography is proposed. Molecular biochromatography with human serum albumin (HSA) immobilized on silica as stationary phase was used to screen and analyse the bioactive compounds in the typical Chinese medicine ofAngelica sinensis (Oliv.) Diels. Ten peaks showed retention on this column, which is based on their affinity for HSA. Ferulic acid and liguistilide were identified as the principal active components, which agrees very well with the results in the literature. A quality control method was also developed based on the simultaneous determination the concentrations of ferulic acid and liguistilide in solutions ofAngelica sinensis (Oliv.) Diels extracted with water and methanol. It was observed that the concentrations of ferulic acid and liguistilide in solution extracted with methanol were 2 and 53 times higher, respectively, than those with water. It was shown that molecular biochromatography is an effective way of analysing and screening biologically active compounds in traditional Chinese medicine.
TL;DR: In this paper, three polymeric adsorbents, two of which had been chemically modified with different hydrophilic functional moieties and the third of which was the corresponding unmodified polystyrene-divinylbenzene (PSDVB) resin, were compared for solid-phase extraction of several polar pesticides and phenolic compounds from water samples.
Abstract: Three polymeric adsorbents, two of which had been chemically modified with different hydrophilic functional moieties and the third, which was the corresponding unmodified polystyrene-divinylbenzene (PSDVB) resin, were compared for solid-phase extraction (SPE) of several polar pesticides and phenolic compounds from water samples. The SPE system was online coupled to a liquid chromatograph with UV detector.