Determination of quinolones and fluoroquinolones in hospital sewage water by off-line and on-line solid-phase extraction procedures coupled to HPLC-UV.

In this work, the development of two solid-phase extraction procedures (off-line and on-line formats) for the identification and quantification of several (fluoro)quinolones in hospital sewage water by HPLC-UV is described. Both procedures are based on the use of C18 and anion exchange (SAX) sorbents for the preconcentration and clean-up steps, respectively, and all variables influencing both steps were optimised. In the off-line format, after its pH was adjusted to 2.

Detection of coexisting protein conformations in capillary zone electrophoresis subsequent to transient contact with sodium dodecyl sulfate solutions.

Non-native conformations of proteins were generated by temporary contact with aqueous solutions of sodium dodecyl sulfate (SDS) and separated from the native state with capillary zone electrophoresis (CZE) in alkaline borate buffer deficient of SDS. Nine proteins at concentrations of 2.0 or 3.

Determination of macrolide antibiotics in porcine and bovine urine by high-performance liquid chromatography coupled to coulometric detection.

A high-performance liquid chromatography method coupled to coulometric detection has been applied for the determination, in a single run, of up to eight macrolide antibiotics (erythromycin [ERY], tylosin [TYL], tilmicosin [TILM], spiramycin 2 [SPI 2], spiramycin 3 [SPI 3], josamycin [JOS], kitasamycin [KIT], and rosamicin [ROS]) in spiked porcine and bovine urine. Quantification was performed using matrix-matched calibration with roxithromycin (ROX) as the internal standard. The detection limits for each drug were below 3.

Stability of fluoroquinolone antibiotics in river water samples and in octadecyl silica solid-phase extraction cartridges.

Intensive use of antibiotics in human and veterinarian medicine and in industrial farming (food additives) has resulted in the transport of important quantities of the active ingredients to environmental waters. Environmental analysis usually requires sample storage for certain periods of time and, consequently, it is of great importance to know the stability of antibiotics in these kinds of sample. Thus, in this work the stability in river water of oxolinic acid (Oxo) and ciprofloxacin (Cip), taken as representatives of fluoroquinolone and quinolone antibiotics respectively, has been evaluated.

Capillary zone electrophoresis of metal-binding proteins in formic acid with UV- and mass spectrometric detection using cationic transient capillary isotachophoresis for preconcentration.

A capillary zone electrophoresis (CZE) method with preceding cationic transient capillary isotachophoresis (tCITP-CZE) was developed for uncoated fused-silica capillaries to analyze metal-binding proteins (MBPs) of clinical relevance. UV detection was followed by mass spectrometry (MS). Optimization was done with model proteins of properties similar to relevant human MBPs.

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.

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.

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.

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.

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.

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.

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).

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.