摘要:

The assays that have one of the reactant species immobilized onto a solid support are described as solid phase assays. During the last 20 years a large number of such assays has been developed, the majority of which are quantitative analytical methods known under the general term ELISA (Enzyme Linked ImmunoSorbent Assay). Solid phase assays, in general, have widely been used in Biochemistry, Clinical Chemistry, and Biotechnology, mainly for analytical purposes, and for the detection of specific macromolecules or the study of interactions between various molecules, as well.

ISSN:1082-6076    

DOI:10.1081/JLC-100102044

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Factor analysis has long been applied to the systematic investigation of chromatographic data. In this paper, two factor analyses, Principal Component Analysis and Correspondence Factor Analysis, are explained. The two approaches are applied to a trial set of chromatographic data. In the first part, the mathematical processes are shown. Particular attention is paid to the data pre-processing with correspondence factor analysis. Next, the results obtained from the two factor analyses are illustrated with two graphs, which are compared to the corresponding tridimensional graphs. Finally, the physico-chemical meaning of the two factor analyses are explained with the use of physico-chemical properties of solutes.

ISSN:1082-6076    

DOI:10.1081/JLC-100102045

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Ion-exclusion chromatography using a high-capacity sulphonated polystyrene-divinylbenzene (PS-DVB) resin was evaluated for the separation of a range of carboxylic and aromatic acids. The parameters affecting the retention behaviour of these acids were examined in relation to their chemical structure. Results obtained on the ion-exclusion column for the separation of aromatic acids were similar to those obtained on a C18column. The ion-exclusion column exhibited both the ion-exclusion effect for the separation of hydrophilic carboxylic acids and the hydrophobic interaction for the separation of aromatic acids, which offered the possibility of simultaneous separation of carboxylic and aromatic acids by careful selection of separation conditions such as column temperature and content of organic modifier.

ISSN:1082-6076    

DOI:10.1081/JLC-100102046

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Strong cation and anion-exchangers were synthesized from phenylhexyl-bonded silica gel. These ion-exchange silica gels were stable after continuous flushing with over 45,000 column volumes of 25 mM disodiumhydrogen phosphate in 50% methanol solution. Their chromatographic specificities were studied for separation of saccharides, and drugs.

ISSN:1082-6076    

DOI:10.1081/JLC-100102047

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A solid phase extraction method for anabolic steroids and related substances in calf urine is reported, that is suitable as a screening method for illegal growth promoters. Two types of sorbent were used: a reversed phase C18 material and a polar alumina material. After overnight enzymatic deconjugation, the 5-mL sample was first brought on the C18 column. This column was washed with 55% methanol in water and was then eluted with 95% acetone in water. The extract was directly brought on the alumina column. The run-through and an additional elution with 95% acetone in water were collected. The final extracts were analysed with an HPLC-DAD method described previously. The steroids are separated on a Superspher RP-Select B column with a gradient mobile phase consisting of acetonitrile and water. The method was found to be suitable for at least 19 illegally used anabolic steroids, having recoveries ranging from 65–110% at a spiking level of 25 ng/mL. Detection limits ranged from 0.6–80 ng injected amount or 1–160 ng/mL urine.

ISSN:1082-6076    

DOI:10.1081/JLC-100102048

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A quantitative liquid chromatographic method for the determination of sulfamethazine (SMZ), N4-acetyl sulfa-methazine (N4-acetyl-SMZ), and desamino sulfamethazine (desamino-SMZ) in egg albumin and egg yolk is described. Egg albumin or yolk was homogenized in acetonitrile and centrifuged. The supernatant was evaporated to dryness and residue reconstituted in the mobile phase. Albumin extract was directly analyzed by high performance liquid chromatography (HPLC). Hexane was added to the yolk sample, vortex mixed, and centrifuged to separate the layers. The top hexane layer was removed and a small amount of salt was added to break the emulsions. The lower aqueous layer was analyzed by HPLC. The HPLC system included a reversed phase column, a gradient mobile phase of 5–15% acetonitrile and 0.01M phosphate buffer, and a UV detector set at 268 nm. The recovery of SMZ and N4-acetyl-SMZ, both fortified at 1 ppm levels, from egg albumin was 101 and 88% and from egg yolk was 79 and 91%, respectively. The recovery of desamino-SMZ at 2 ppm fortification level from egg albumin and egg yolk was 84 and 63%, respectively.

ISSN:1082-6076    

DOI:10.1081/JLC-100102049

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Based on reversed phase high performance liquid chromatography with gradient elution and diode-array detection (HPLC-DAD) a specific and sensitive assay for the quantitation of diacetylmorphine (heroin, DAM) and its primary and secondary metabolites 6-acetylmorphine, morphine, morphine-3-β-D-glucuronide, morphine-6-β-D-glucuronide and nor-morphine in plasma was developed. Confirmation of the peak assignment was performed by atmospheric pressure ionization-mass spectrometry (API-MS). Plasma samples were extracted on C18ODS-2 columns using an automated solid-phase extraction (SPE) unit. The recovery was between 45 and 68%.

ISSN:1082-6076    

DOI:10.1081/JLC-100102050

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The performance of two different types of immobilized artificial membrane (IAM) stationary phases, IAM PC DD 1 and IAM PC DD 2 was studied with a series of model compounds as well as anti-inflammatory and analgesic drugs. The influence of the composition of the mobile phase and sample preparation on the chromatographic retention of selected compounds was investigated. Premature column failure was evidenced for both types of columns by a continuous decrease of k'IAMvalues over time. pH of the mobile phase strongly influenced k'IAMvalue of ionizable compounds. The k'IAMvalue of the neutral form was always 2 to 7 fold higher than the value of the corresponding ionized form, depending on the compound and the type of IAM. A linear relationship was found between log k'IAMand the percentage of acetonitrile in the mobile phase. However, extrapolation of the log k'IAMvalue at 0% acetonitrile was improved when the pH and the ionic strength of acetonitrile-containing mobile phases were adjusted to the values of the purely aqueous mobile phase.

ISSN:1082-6076    

DOI:10.1081/JLC-100102051

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Car paints not only must be stable to sunlight effects but also must protect paint sub-layers. For this purpose, the transparent melaminic/acrylic paints of recent formulation contain added stabilisers (UV-As) which are able to absorb UV radiation.

ISSN:1082-6076    

DOI:10.1081/JLC-100102052

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor