摘要:

Ion chromatography (IC) combined with condensation nucleation light scattering detection (CNLSD) is shown here to be a highly sensitive method for cationic species determination, with limits-of-detection (LODs) at ng/mL levels. Furthermore, unlike the common conductivity detection method, higher than normally used acid concentration eluents can be used, resulting in faster elution of the analytes. The use of a suppressor is also eliminated since CNLSD is mainly dependent on the involatility of the analyte relative to the mobile phase, making the detection method universal for most cationic species.

ISSN:1082-6076    

DOI:10.1081/JLC-100101699

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

An immunoaffinity column generated by cross-linking a polyclonal chicken antibody with CNBr-activated Sepharose 4B was used for isolation of 1,3,7,8-tetrachlorodibenzo-p-dioxin (1,3,7,8-TCDD) from bovine milk. Direct application of a milk sample, even if diluted 1:50 with 0.05% Triton X-100, interfered with the binding of 1,3,7,8-TCDD to the column. Pre-immunoaffinity column clean-up using liquid-liquid extraction followed by solid phase extraction produced excellent retention of 1,3,7,8-TCDD by the column. The TCDD was easily eluted by increasing the Triton X-100 concentration to 0.5%. Although analysis of milk samples requires more stringent clean up than serum samples, the immunoaffinity chromatography column procedures provide specific clean-up for these samples.

ISSN:1082-6076    

DOI:10.1081/JLC-100101700

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Isocratic reverse phase HPLC method was elaborated and optimized for simultaneous determination of pyridinoline (PD), deoxypyridinoline (DPD) and isodesmosine (IDES) in urine and in tissues within approximately 16 minutes. Mobile phase is 0.02 M heptafluorobutyric acid (HFBA) with 0.01 M (NH2)2SO4and 8 - 12 % acetonitrile (ACN), at pH 1.55, flow rate 0.5 mL/min. and temperature of 40°C. The addition of ammonium sulphate affects positively the quality of chromatographic separation. The glass column 150 × 3 mm is filled with 7 μm spherical silica C18. The concentrations of determined substances are monitored by detector of fluorescence at λEX/λEM= 297/400 nm for both PD and DPD, and at λEX/λEM= 275/320 nm for IDES. Both PD and DPD are measurable with the same sensitivity limit of 200 femtomols; in the case of IDES the determination sensitivity is approximately 5x lower (1 pmol).

ISSN:1082-6076    

DOI:10.1081/JLC-100101701

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

For demonstrating the presumption that on the hydrous zirconium oxide loaded porous polymer resin (Zr-gel) under alkaline pH the recognition of a position of hydroxyl or carboxyl group was ascribed to formation of a chelate ring, the retention behaviors of hydroxyl and other substituent aliphatic carboxylic acids were evaluated on titania synthesized in this laboratory and compared with those of zirconia provided by the manufacturer. The retention behavior supported the formation of chelate ring and suggested the priority of forming a five-membered ring. On comparison titania and zirconia, the distinct elution order was shown in retention behavior of 2-hydroxycarboxylic acids. It might be ascribed to the difference in the bond angle and distance between metal ion and two oxygen atoms of hydroxyl group and carboxylate anion on formation of chelate ring.

ISSN:1082-6076    

DOI:10.1081/JLC-100101702

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The characterization of calcined titanias with regard to physical properties as packing materials and crystal forms by X-ray powder diffraction, and the examination of how the ion- and ligand-exchange properties of titania shall be influenced by varying calcination temperature, were demonstrated to elucidate the relationship between the chromatographic behavior and the change of surface state accompanied with varying calcination temperature. The ligand-exchange properties in this experiment were regarded as the formation of chelate rings of 2-hydroxyl aliphatic carboxylic acids. We observed that the physical properties of titania reflected, exactly, the variation in X-ray diffraction patterns with calcination temperature. We found that only calcined titania behaving as cation-exchanger exhibited retention behavior correlated with changes in surface hydroxyl group, and that rutile formed by calcination did not behave as ion- and ligand-exchangers. The absence of these properties would account for losing the surface hydroxyl group and the coordinatively bonded water by calcination.

ISSN:1082-6076    

DOI:10.1081/JLC-100101703

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A high-performance liquid chromatographic method with ultraviolet radiation absorbance detection has been developed for the determination of the principal opiates (heroin, 6-monoacetylmorphine, morphine, codeine) in human hair. An amount of 100 mg hair was incubated with 2 mL HCl 0.1 M at 56°C overnight and it was then extracted by solid-phase extraction using reversed-phase/ion exchange cartridges. Chromatography has been performed using a C18reversed-phase column with a mobile phase consisting of water-acetonitrile (70:30 v/v) containing 0.01 M NaH2PO4and 0.002 M sodium laurylsulphate at a final pH of 2.1. The linearity of the method was obtained in the concentration range of 0.5-50 ng/mg hair for 6-monoacetylmorphine, morphine and codeine, and of 5–200 ng/mg hair for heroin. The accuracy of the methodology was assessed using reference material from National Institute of Standards and Technology consisting of human hair segments and powdered human hair soaked with opiates.

ISSN:1082-6076    

DOI:10.1081/JLC-100101704

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

In order to find a Centrifugal Partition Chromatography (CPC) solvent system that can be used as a general prefractionation step for crude plant extracts, twelve two-phase systems were compared. The butanol: ethyl acetate: water 3:2:5 (v/v/v) system gave good separation for polar compounds, and the heptane: ethyl acetate: methanol: water 6:1:6:1 (v/v/v/v) system was found to be effective for the separation of nonpolar compounds and somewhat less for polar compounds.

ISSN:1082-6076    

DOI:10.1081/JLC-100101705

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The HPLC capacity factors(k') measured on a C18column, using methanol-water mobile phase of different compositions, were determined for 15 heterocyclic nitrogen compounds. The linear relationship between the log k' values and the percentage of the methanol in the eluent was studied for each compound. The log kW′ values of these compounds were obtained by extrapolating the retention data in binary solvent system to pure water eluent.

ISSN:1082-6076    

DOI:10.1081/JLC-100101706

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Several chloroformic extracts containing some sesquiterpene lactones from autochtonous plants ofParthenium hysterophorus, collected in the province of Salta (Argentina), were separated and identified by high performance reversed-phase liquid chromatography with C18column and propanol-water mobile phases, using gradient elution and concentrations of propanol larger than 10% (v/v). Lactones previously purified and characterized by H1RMN, C13RMN, IR, and mass spectrometry, were used as standards.

ISSN:1082-6076    

DOI:10.1081/JLC-100101707

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Two separate High Performance Liquid Chromatography procedures have been developed for the assay of a remifentanil - propofol mixture. The separation and quantitation of remifentanil were achieved on an ethylsilane column at ambient temperature (23°C) using a mobile phase of 62:38 v/v 0.01 M phosphate buffer pH 2.5-acetonitrile at a flow rate of 2 mL/min with detection at 210 nm. A methylsilane column at 23°C using the same mobile phase at a flow rate of 1.0mL/min with detection at 210 nm was used for propofol. The methods showed linearity for remifentanil and propofol in the 1.0–45 and 15–75 μg/mL ranges, respectively. Accuracy and precision were in 0.08 - 2.3% and 0.2 - 1.2% ranges, respectively, for both drugs. The limits of detection for remifentanil and propofol were 200 and 250 ng/mL, respectively, based on a signal to noise ratio of 3 and a 10 μL injection.

ISSN:1082-6076    

DOI:10.1081/JLC-100101708

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor