Biomedical subjects

Guy Bordin

Publications and source records attributed to Guy Bordin.

8 recordsLinked to original sources

PubMed2003

Trace enrichment of (fluoro)quinolone antibiotics in surface waters by solid-phase extraction and their determination by liquid chromatography-ultraviolet detection.

A new and simple analytical methodology for the simultaneous analysis of acidic and zwitterionic (fluoro)quinolones in surface waters at trace concentration level is presented. The method is based on the preconcentration of these analytes by a solid-phase extraction procedure and their subsequent quantification by liquid chromatography using ultraviolet detection. The breakthrough volumes of the selected (fluoro)quinolones in four different sorbents--C18, styrenedivinylbenzene (SDB), C18-cation-exchange and SDB-cation-exchange--have been evaluated and varied between 25 and 150 ml depending on the antibiotic and the sorbent used. An exhaustive study of the influence of sample pH on the preconcentration step has been carried out in order to find a suitable procedure for extraction of acidic and zwitterionic FQs in one single step. Under optimum conditions, it was possible to percolate up to 250 ml of water solution onto both C18 and SDB-cation-exchange cartridges with quantitative recoveries for all the analytes tested. However, matrix components of the surface water samples analysed negatively affected the recoveries of the analytes in the SDB-cation-exchange cartridge and thus, C18 cartridges were finally selected for the analysis of the (fluoro)quinolones in lake and river water. The limits of detection achieved with this procedure varied between 8 and 20 ng l(-1) proving its suitability for the determination of the (fluoro)quinolones in water samples at a realistic environmental concentration level.

Anti-Bacterial Agents↗

PubMed2003

Determination of haemoglobin A(1c) by liquid chromatography using a new cation-exchange column.

The use of a new cation-exchange column, ProPac SCX-10, for the determination of haemoglobin A(1c) (HbA(1c)) by high-performance liquid chromatography is described. After optimization of the analytical method for the separation of the various isoforms of haemoglobin with the ProPac SCX-10 column, the method was applied to the determination of HbA(1c) in blood from 59 volunteers. Three of the 59 had previously been diagnosed as diabetics. Interference studies for carbamylation, acetylation and pre-HbA(1c) were carried out via "in-vitro" experiments. No interference due to carbamylation was observed at the urea values normally found in uremic patients undergoing dialysis. No interference from pre-HbA(1c) was detected either. The method is able to separate haemoglobin A (alpha(2)beta(2)), haemoglobin S (haemoglobin from sickle cell anaemia patients) and haemoglobin A(2) (alpha(2)delta(2)) without interference. The method of Hampel was applied to detect outliers. A value of 3.29+/-0.44% (2sigma) for HbA(1c) was obtained in the analysis of 56 blood samples from non-diabetics. This average value is lower than that reported by most of the methods currently used in routine analyses.

Cation Exchange Resins↗

PubMed2003

Comparative study of coulometric and amperometric detection for the determination of macrolides in human urine using high-performance liquid chromatography.

A high-performance liquid chromatography (HPLC) method using chromatographic conditions optimised in a previous work was applied for the separation of three macrolide antibiotics roxithromycin (Rox), oleandomycin (Ole) and rosamicin (Ros) and further determination of two of them, roxithromycin (Rox) and oleandomycin (Ole), in human urine samples. A comparative study of the behaviour of these macrolides under the two types of electrochemical detection (EC) widely coupled with HPLC, that is coulometric (EC-C) and amperometric (EC-A), was carried out by applying the same multiresidue method. From the assays performed using both detectors the comparison was made taking relevant criteria such as detection limits, linearity, recovery and precision values into account. As a result of this comparison, the coulometric detector appears slightly more suitable than the amperometric one for macrolide analysis.

Anti-Bacterial Agents↗

PubMed2003

Development of a capillary zone electrophoresis-electrospray ionisation tandem mass spectrometry method for the analysis of fluoroquinolone antibiotics.

The applicability of a capillary zone electrophoresis-electrospray ionisation tandem mass spectrometric (CZE-ESI-MS-MS) method for the separation of nine fluoroquinolones was investigated. Method optimisation involved systematic trouble-shooting starting with the type and duration of capillary pre-washing and conditioning, the choice of both the CE run buffer, MS sheath liquid, CE run potential, ESI spray voltage, sheath gas flow-rate, MS capillary voltage and CE capillary and MS capillary temperatures. Another extremely important factor was found to be the degree to which the CE capillary protrudes into the ESI chamber as well as whether or not sheath gas and spray voltage are employed during the CE injection or not. The importance of the latter has, to our knowledge, not been addressed elsewhere. Nine fluoroquinolones have been separated and detected in a single run by this technique.

Anti-Infective Agents↗

PubMed2002

Multiresidue determination of (fluoro)quinolone antibiotics in swine kidney using liquid chromatography-tandem mass spectrometry.

New antibiotics were recently developed, among which are the (fluoro)quinolones. This paper presents an analytical method which allows the determination of 11 (fluoro)quinolones in swine kidneys: norfloxacin, ofloxacin, cinoxacin, oxolinic acid, nalidixic acid, flumequine, enrofloxacin, enoxacin, ciprofloxacin, danofloxacin and marbofloxacin. The procedure involves a rapid and efficient pre-treatment by solid-phase extraction (recoveries 83-98%), followed by the sensitive and selective determination of all compounds in a single run using LC-ESI-MS-MS. Multiple reaction monitoring (MRM) was used for selective detection of each (fluoro)quinolone. Quinine was selected as internal standard. The accuracy of the method, expressed as recovery, was between 89 and 109%; the repeatability had a maximum RSD lower than 15%. The limits of detection (LOD) were much lower than the respective Maximum Residue Limits (MRL)/4.

Animals↗

PubMed2002

Recent developments in quantification methods for metallothionein.

The metallothioneins (MT), a family of proteins with relatively low molecular weight (6-7 kDa), are characterised by the intrinsic presence of 20 cysteinyl groups in their structure, which confers unique metal binding properties to the molecule. Since MT are involved in biological roles, quantification of MT remains an important task. To date, a large number of determination methods have been developed. In this paper recent developments, from 1995 to the present, in methodology employed in quantification studies of total MT and MT polymorphism are described. Different fields were taken into consideration, such as (i) separation techniques and hyphenated systems, (ii) electrochemical methods, (iii) immunological methods and (iv) quantification of MT mRNA. The data presented are based on our own and published results. A brief overview of the use of metallothionein as a biomarker is included as a relevant example of the importance of MT quantification. Finally, general problems associated with determination and evaluation of obtained results within the above four topics are mentioned.

Animals↗

PubMedDate not supplied

Validation of an analytical procedure for the determination of oxidative hair dyes in cosmetic formulations.

A high range and variety of cosmetic formulations that contain oxidative hair dyes and matrix-forming compounds have been industrially developed over recent years and are now available on the international market. Member states of the European Union are responsible for conducting analyses of cosmetic products as deemed necessary by law and European regulation enforcement. Therefore, inspection authorities as well as the cosmetics trade and industry need validated analytical methods for the identification, characterization, and/or quality control of specific active ingredients or formulations with the aim of implementing the European Union Cosmetic Directives (76/768/ECC, 95/17/EC). In this frame, we validated a candidate reference method that enables the identification and quantification of hair dye-forming compounds. This method consists of a separation by RP-HPLC coupled with a DAD after a liquid-liquid extraction procedure for separating matrix components from the dye-forming compounds. The validation of the method includes common criteria such as the repeatability of the analysis and the establishment of figures of merit, as well as statistical evaluations and quality assurance in order to follow the recommendations of the Eurachem guide for analytical measurements.

Chromatography, High Pressure Liquid↗

PubMedDate not supplied

Optimization and validation of an analytical procedure for the determination of oxidative hair dyes in commercial cosmetic formulations.

A method has been developed and validated for the analysis of commonly used intermediates of oxidative hair dyes in commercial cosmetic formulations, including both liquid and cream forms, in dark and blonde shades. The commercial formulations are submitted to extraction by an organic solvent, and the resulting aqueous phase is analyzed by reverse-phase HPLC with a gradient elution and detection with DAD and/or ESI-MS-MS. A spectra library containing 200-400 nm spectra of the target substances and their HPLC retention times has been recorded for the identification. The quantification of the target substances is also performed after spiking of the commercial formulations, using an external calibration. The recoveries obtained are very good for all selected intermediates. The whole procedure has been found to be highly suitable for the identification and quantification of dye intermediates. Also implemented has been a database containing (a) the retention times, (b) the spectral, MS, and MS/MS characteristics of the intermediates, (c) acidity constant values of some intermediates of interest experimentally determined and compared to the available NIST values, (d) the chromatographic conditions used, (e) the behavior towards extraction of dye intermediates, and (f) matrix compounds.

Calibration↗