| 1. |
- Borén, Kristina, et al.
(författare)
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Rapid ion-exchange chromatography for preparative separation of proteins IV. Application to bovine carbonic anhydrase III from skeletal muscle
- 1991
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Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673 .- 1873-3778. ; 588:1-2, s. 139-145
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Tidskriftsartikel (refereegranskat)abstract
- Bovine muscle carbonic anhydrase III was purified to homogeneity by the strategy of rapid ion-exchange chromatography. The ionic exchanger used was CM-cellulose, and this is the first application of this technique on a cation exchanger. Nitrogen gas was used to pressurize the chromatographic column to accelerate the elution. The results show that proteins with high isoelectric points can also be purified in this way. The procedure is very time-saving compared with conventional chromatography, reducing the elution time five-to ten-fold. The proteins are in addition protected against oxidation by air.
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| 2. |
- Jonsson, Susanne, 1965-, et al.
(författare)
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Analysis of mono- and diesters of o-phthalic acid by solid-phase extractions with polystyrene–divinylbenzene-based polymers
- 2002
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Ingår i: Journal of Chromatography A. - 0021-9673 .- 1873-3778. ; 963:1-2, s. 393-400
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Tidskriftsartikel (refereegranskat)abstract
- Retention mechanisms of an unmodified and a hydroxylated polystyrene–divinylbenzene polymer were studied by solid-phase extraction of o-phthalic acid and some of its mono- and diesters from purified water and then analysing by GC–MS. The monoesters and phthalic acid were retained only when protonated (i.e. acidified with HCl to pH 0.9). Of all elution solvents tested, ethyl acetate gave the best overall recoveries (61–89%) with both polymers. Applicability to complex matrixes (e.g. acidogenic landfill leachates) was examined by introducing a washing step with acetone in acidified water (pH 0.9) to eliminate volatile fatty acids (C2–C6) from the cartridge. Finally, the method was tested on real samples.
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| 3. |
- Jonsson, Susanne, 1965-, et al.
(författare)
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Quantification of volatile sulfur compounds in complex gaseous matrices by solid-phase microextraction
- 2002
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Ingår i: Journal of Chromatography A. - 0021-9673 .- 1873-3778. ; 963:1-2, s. 57-64
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Tidskriftsartikel (refereegranskat)abstract
- Procedures were assessed for quantifying nine volatile sulfur compounds found in complex gaseous samples collected at a biogas-production plant and a sewage treatment plant. The target compounds were extracted by solid-phase microextraction (using the 75-╡m Carboxen-polydimethylsiloxane fiber coating) at 22░C for 20 min, and analyzed by GC-MS. Detection limits ranged between 1 pptv (v/v) for carbon disulfide and 470 pptv (v/v) for hydrogen sulfide. High amounts of organic compounds were found during full-scan analysis of the samples and standard additions to individual sub-samples revealed that the analysis was subject to matrix effects. However, the functions obtained by standard additions were still linear and quantification was possible for all the compounds tested except hydrogen sulfide. No detectable losses were observed during storage in the sampling containers, made of Tedlar film, over a storage period of 20 h. However, water permeated through the walls and the relative humidity in the bag increased during storage until it reached the ambient level. Finally, it was shown that the drying agent, CaCl2, caused no detectable losses of any of the compounds. ⌐ 2002 Elsevier Science B.V. All rights reserved.
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| 4. |
- Lagesson, V., et al.
(författare)
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Identification of compounds and specific functional groups in the wavelength region 168-330 nm using gas chromatography with UV detection
- 2000
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Ingår i: Journal of Chromatography A. - 0021-9673 .- 1873-3778. ; 867:1-2, s. 187-206
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Tidskriftsartikel (refereegranskat)abstract
- A GC-UV instrumental set up with two different GC units has been used for determination of specific functional groups and compounds in complex mixtures. Separations have been made using a micro gas chromatograph built into a gas flow cell and by means of an external capillary gas chromatograph linked to the same gas flow cell. Four various applications (cigarette smoke, petroleum, dust, flavour) have been performed in order to demonstrate the potential of the GC-UV method. Gas phase UV spectra have been recorded in the region of 168-330 nm. Based on a gas phase spectrum reference library the identification of unknowns as well as the determination of specific functional groups have been achieved. A table showing the spectral shapes and positions of the absorption bands for 50 specific functional groups is presented. The advantage of using derivative spectra in order to amplify spectral details and improve selectivity is discussed. Regarding sensitivity, it has been found that identifications can be made in the mid-pg range and limit of detection for naphthalenes are at a level of 0.5-3 pg/s. Copyright (C) 2000 Elsevier Science B.V.
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| 5. |
- Landberg, Eva, et al.
(författare)
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Temperature effects in high-performance anion-exchange chromatography of oligosaccharides
- 1998
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Ingår i: Journal of Chromatography A. - 0021-9673 .- 1873-3778. ; 814:1-2, s. 97-104
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Tidskriftsartikel (refereegranskat)abstract
- High-performance anion-exchange chromatography (HPAEC) with pulsed amperometric detection has been widely used for analysis of mono-, oligo- and polysaccharides. Many factors that affect separation of carbohydrates by HPAEC have been evaluated, however effect of temperature has not been carefully studied. In the present study, neutral and sialylated oligosaccharides from human milk and different types of N-linked oligosaccharides were analysed by HPAEC at temperatures ranging from 13 to 30°C. N-Acetyl neuraminic acid, galacturonic acid and stachyose were also analysed since they have been used as internal standards when analysing various oligosaccharides by HPAEC. All oligosaccharides showed decreased retention times with increased temperature. Even small differences in temperature (i.e. ±5°) resulted in considerable changes in retention times. In addition, individual oligosaccharides showed different relative changes in retention time with increased temperature. By changing the temperature, a switch in elution order of individual oligosaccharides were sometimes found. These results show that retention times relative to an internal standard cannot be used for oligosaccharide identification unless temperature is carefully controlled. Regulation of temperature is also a valuable tool in achieving optimal separation of oligosaccharides by HPAEC.
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| 6. |
- Öhman, Daniel, 1973-, et al.
(författare)
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Simultaneous determination of reboxetine and O-desethylreboxetine enantiomers using enantioselective reversed-phase high-performance liquid chromatography
- 2002
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Ingår i: Journal of Chromatography A. - 0021-9673 .- 1873-3778. ; 947:2, s. 247-254
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Tidskriftsartikel (refereegranskat)abstract
- Current knowledge of stereoselective pharmacokinetics and different potencies of drug enantiomers requires the performance of stereoselective analysis during therapeutic drug monitoring in clinical practice. However, in the case of the new antidepressant drug reboxetine, no effort has been made so far to find a such a suitable system. Therefore, as a step towards developing an enantioselective bioanalytical method for reboxetine and the O-desethylreboxetine metabolite, three stereoselective chromatographic approaches have been investigated. Several chiral columns were tested, among them Chiral-AGP, ChiraGrom 2 and Chiral-CBH, which were able to simultaneously separate the two compounds into enantiomers in total running times of 28, 18 and 12 min, respectively.
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| 7. |
- Bossi, A, et al.
(författare)
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Capillary electrophoresis coupled to biosensor detection
- 2000
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Ingår i: Journal of Chromatography A. - : Elsevier Science B.V., Amsterdam.. - 0021-9673 .- 1873-3778. ; 892:02-jan, s. 143-153
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Tidskriftsartikel (refereegranskat)abstract
- The present review highlights some modern aspects of biosensor revelation, a detection method which has already found a large number of applications in healthcare, food industry and environmental analysis. First, the concept of bio-recognition, which is at the heart of biosensor technology, is discussed, with emphasis on host-guest-like recognition mechanisms. This detection device has been successfully coupled, in its first applications, to chromatographic columns, which allow a high resolution of complex mixtures of analytes prior to interaction with the biosensing unit. The properties of the transducing elements, which should generate a signal (e.g., electrochemical, thermal, acoustic, optical) of proper intensity and of relative fast rise, are additionally evaluated and discussed. The review then focuses on potential applications of biosensing units in capillary electrophoresis (CE) devices. CE appears to be an excellent separation methodology to be coupled to biosensor detection, since it is based on miniaturized electrophoretic chambers, fast analysis times, complete automation in sample handling and data treatment and requires extremely small sample volumes. Although only a few applications of CE-based biosensors have been described up to the present, it is anticipated that this hyphenated technique could have a considerable expansion in the coming years, (C) 2000 Elsevier Science B.V. All rights reserved.
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| 8. |
- Bossi, Alessandra, et al.
(författare)
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Properties of poly-aminophenylboronate coatings in capillary electrophoresis for the selective separation of diastereoisomers and glycoproteins
- 2004
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Ingår i: Journal of Chromatography A. - : Elsevier. - 0021-9673 .- 1873-3778. ; 1023:2, s. 297-303
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Tidskriftsartikel (refereegranskat)abstract
- The polymerisation of 3-aminophenylboronic acid (APBA) in aqueous environment has been used for the open tubular modification of capillary electrophoresis (CE) capillaries. Being poly-APBA endowed with boronic acid, aromatic rings and secondary amines groups, it posses a variety of functional groups affecting selectivity. Diastereoisomers (e.g. ascorbic and isoascorbic acid) and proteins (e.g. haemoglobins) were successfully separated onto poly-APBA column, by means of a combination of electrophoresis and open tubular electrochromatography. The mechanism of selection was investigated: results indicate an interplay between enhancing or silencing the contribution of the protonable functionahties (amino groups, boronic acid). The properties of APBA polymer coating make it attractive for CE separation and for further application in affinity separations and chip technologies.
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| 9. |
- Concheiro, Marta, et al.
(författare)
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Simultaneous determination of 40 novel psychoactive stimulants in urine by liquid chromatography-high resolution mass spectrometry and library matching
- 2015
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Ingår i: Journal of Chromatography A. - : Elsevier. - 0021-9673 .- 1873-3778. ; 1397, s. 32-42
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Tidskriftsartikel (refereegranskat)abstract
- The emergence of novel psychoactive substances is an ongoing challenge for analytical toxicologists. Different analogs are continuously introduced in the market to circumvent legislation and to enhance their pharmacological activity. Although detection of drugs in blood indicates recent exposure and link intoxication to the causative agent, urine is still the most preferred testing matrix in clinical and forensic settings. We developed a method for the simultaneous quantification of 8 piperazines, 4 designer amphetamines and 28 synthetic cathinones and 4 metabolites, in urine by liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS). Data were acquired in full scan and data dependent MS2 mode. Compounds were quantified by precursor ion exact mass, and confirmed by product ion spectra library matching, taking into account product ions exact mass and intensities. One-hundred pi, urine was subjected to solid phase cation exchange extraction (SOLA SCX). The chromatographic reverse-phase separation was achieved with gradient mobile phase of 0.1% formic acid in water and in acetonitrile in 20 min. The assay was linear from 2.5 or 5 to 500 mu g/L. Imprecision (n = 15) was less than15.4%, and accuracy (n = 15) 84.2-118.5%. Extraction efficiency was 51.2-111.2%, process efficiency 57.7-104.9% and matrix effect ranged from -41.9% to 238.5% (CV less than 23.3%, except MDBZP CV less than 34%). Authentic urine specimens (n = 62) were analyzed with the method that provides a comprehensive confirmation for 40 new stimulant drugs with specificity and sensitivity.
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| 10. |
- Geng, Dawei, 1986-, et al.
(författare)
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Gas chromatography/atmospheric pressure chemical ionization/mass spectrometry for the analysis of organochlorine pesticides and polychlorinated biphenyls in human serum
- 2016
-
Ingår i: Journal of Chromatography A. - Amsterdam, Netherlands : Elsevier. - 0021-9673 .- 1873-3778. ; 1453, s. 88-98
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Tidskriftsartikel (refereegranskat)abstract
- A method using a novel atmospheric pressure chemical ionization source for coupling gas chromatography (GC/APCI) to triple quadrupole mass spectrometry (MS/MS) for the determination of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) regulated by the Stockholm Convention is presented. One microliter injection of a six-point calibration curve of native PCBs and OCPs, ranging from 0.04 to 300 pg/μL, was performed. The relative standard deviation (RSD) of the relative response factors (RRFs) was less than 15% with a coefficient of determination (r2) >0.995. Meanwhile, two calibration solutions (CS), CS 2 (0.4 pg/μL) and CS 3 (4 pg/μL) were analyzed to study the repeatability calculated for both area and RRFs. The RSD for RRF ranged from 3.1 to 16% and 3.6 to 5.5% for CS 2 and CS 3, respectively. The limits of detection (LOD) determined by peak-to-peak signal-to-noise ratio (S/N) of 3 were compared between the GC/APCI/MS/MS and a GC coupled to high resolution mass spectrometry (GC/HRMS) system. GC/APCI/MS/MS resulted in lower LOD for most of the compounds, except for PCB#74, cis-chlordane and trans-chlordane. GC/APCI/MS/MS and GC/HRMS were also compared by performing analysis on 75 human serum samples together with eight QA/QC serum samples. The comparison between GC/APCI/MS/MS system and GC/HRMS system for 16 of the targeted compounds was carried out. No statistically significant difference was discovered. Due to increased sensitivity and user friendly operation under atmospheric pressure, GC/APCI/MS/MS is a powerful alternative technique that can easily meet the specification of GC/HRMS.
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