摘要:

A liquid chromatographic-atmospheric pressure ionization ion spray method for the determination of anatoxin-a, microcystin desmethyl-3, LR, RR, and YR in fish muscle, is described. A salmon muscle sample was extracted with a mixture of methanol-water and acetone. The organic layer was evaporated and cleaned-up using LMS solid phase extraction columns. The method is simple, specific, and requires only small quantities of chemical reagents. The lower limits of quantification were 15, 2, 10, 1, and 10 ng/g for anatoksin-a, microcystin desmethyl-3, LR, RR, and YR, respectively.

ISSN:1082-6076    

DOI:10.1081/JLC-100101444

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The detection of biotin at lower concentration in UV-visible region is difficult because of the low adsorption coefficients. In order to improve this problem, a new migration system, using an exchange reaction between biotin injected and avidin- HABA (2[4’-hydroxyazobenzene] benzoic acid) complex added in running buffer, was developed in the capillary electrophoresis (CE). The use of combination of zwitterionic surfactant (Zwittergent 3–14) and C8 pre-coating capillary enabled this migrating system by suppressing adsorption of avidin for a capillary wall effectively. In this migrating system, the reverse peak height of avidin-biotin complex increased with dependence on concentration of biotin injected. Moreover, the separation of biotin and biocytin was achieved as avidin complex at pH 7 of running buffer. The detection of biotin, contained in a vitamin tablet, was selectively detected avoiding other vitamins by using this CE system. This method enabled detection of only substances having strong affinity with avidin.

ISSN:1082-6076    

DOI:10.1081/JLC-100101445

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

α,β,γδ-Tetraphenylporphine (TPP) was used as a precolumn chelating reagent for reversed-phase high performance liquid chromatographic (HPLC) separation and determination of trace Cu2+, Zn2+and Pd2+. Chelating reactions of TPP with Cu2+, Zn2+, and Pd2+have been optimized in the presence of anionic surfactant sodium dodecyl sulphate (SDS). TPP and its metal chelates were successfully separated on a Nucleosil C18column (150×4.6 mm I.D., 5 μm) with acetone-acetonitrile (37.5: 62.5, v/v) as mobile phase.

ISSN:1082-6076    

DOI:10.1081/JLC-100101446

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Lysozyme adsorption to immobilized Cibacron Blue 3GA using different membrane supports, regenerated cellulose membrane discs, and polysulfone hollow fibers, is investigated in this study. The relevant adsorption properties using traditional chromatographic beads were also measured for comparison. The experimental results demonstrated distinct adsorption properties for different solid supports. The membrane discs possessed the best thermal resistance among the three adsorbents assessed, which essentially results from their higher thermal stability. Moreover, the saturation capacity of lysozyme onto membrane discs was found close to the ligand density for gel beads, whereas the hollow fibers were of much greater saturation capacity.

ISSN:1082-6076    

DOI:10.1081/JLC-100101447

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

I have proposed “Centrifugal Precipitation Chromatography”[1] as a new method for the precipitation of proteins using a linear gradient of ammonium sulfate (AS). However data on the solubility of proteins under these specific conditions are not available. Therefore, the following method is proposed to obtain these data.

ISSN:1082-6076    

DOI:10.1081/JLC-100101448

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

We describe a new method for the analysis of hypericins from crude extracts ofHypericum perforatum(St. John’s Wort) using HPLC. Hypericin and pseudohypericin and related compounds were separated in 15 minutes using a simple isocratic elution method on a modified phenyl column. This isocratic method permits the quantitative and rapid analysis of hypericins in crude acetone samples.

ISSN:1082-6076    

DOI:10.1081/JLC-100101449

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A capillary electrophoresis method was developed to quantify thiabendazole in various fruits and vegetables. Thiabendazole was extracted by adding 20 mL of methylene chloride to a 5 gram sample followed by homogenization and centrifugation. A 5 mL aliquot of the supernatant was removed and evaporated under nitrogen. The residue was reconstituted in 1 mL of HPLC grade water acidified with phosphoric acid (pH 3). Quantitation was performed using UV photodiode detection at 298 nm. Intra-assay and inter-assay reproducibility studies run at concentrations from 0.88 ppm to 20.88 ppm indicated the procedure was reproducible.

ISSN:1082-6076    

DOI:10.1081/JLC-100101450

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Two methods, one on the basis of relative error in yi(in that case wishould be taken as 1/yi2) (YWLS) and another on the basis of 1/xi2as a weighting factor (XWLS), for the calculation of calibration function are reported and compared with conventional ordinary (OLS) and simple weighted least squares method (WLS). By these procedures the calibration functions for the TLC determination of some triazine herbicides are represented more strongly than by the ordinary least squares method mainly in the cases of heteroscedasticity. Instead of the coefficient of correlation, six coefficients of quality are used to characterize the quality of the calibration functions.

ISSN:1082-6076    

DOI:10.1081/JLC-100101451

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Seasonal dependence of 20-hydroxyecdysone content ofSerratula wolffiiwas monitored. Thin-layer chromatography was used after a single clean-up using polyamide. High performance liquid chromatography was employed for the analysis, after removal of the high excess of flavonoids and other impurities using a clean-up on both C18 and polyamide.

ISSN:1082-6076    

DOI:10.1081/JLC-100101452

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The use of vancomycin as a chiral selector was introduced by D. W. Armstrong. This macrocyclic antibiotic was used either free in solution for thin-layer chromatography (TLC) and capillary electrophoresis (CE) or covalently bonded to silica gel in the case of high performance liquid chromatography (HPLC). Its possible use in countercurrent chromatography (CCC) or centrifugal partition chromatography (CPC) is also of interest since these techniques have preparative capabilities which make them attractive for multi-gram scale production of enantiomers.

ISSN:1082-6076    

DOI:10.1081/JLC-100101453

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor