Biomedical subjects

C Cháfer-Pericás

Publications and source records attributed to C Cháfer-Pericás.

5 recordsLinked to original sources

PubMed2006

In-tube solid-phase microextraction-capillary liquid chromatography as a solution for the screening analysis of organophosphorus pesticides in untreated environmental water samples.

This paper describes a method for the selective screening of organophosphorus pesticides in water. In-tube solid-phase microextraction (SPME) in an open capillary column coupled to capillary liquid chromatography (LC) with UV detection has been used to effect preconcentration, separation and detection of the analytes in the same assembly. For in-tube SPME two capillary columns of the same length and different internal diameters and coating thicknesses have been tested and compared, a 30 cm x 0.25 mm I.D., 0.25 micro m thickness coating column, and a 30 cm x 0.1 mm I.D., 0.1 micro m of coating thickness column. In both columns the coating was 95% dimethylpolysiloxane (PDMS)-5% diphenylpolysiloxane. The proposed methodology provided limits of detections (LODs) for the tested organophosphorus pesticides in the 0.1-10 micro g/L range, whereas the direct injection of the samples onto the capillary LC system provided LODs in the 50-1000 micro g/L range. The sensitivity of the proposed in-tube SPME-capillary LC method is adequate to monitorize the analyte levels in drinking water. Several triazines, polycyclic aromatic hydrocarbons (PAHs), nonylphenol, organochloride pesticides or polybrominated diphenyl ethers (PBDEs) have been evaluated as possible interferents. The reliability of the described method is demonstrated by analysing different real water samples.

Chromatography, Liquid↗

PubMed2006

On-fibre solid-phase microextraction coupled to conventional liquid chromatography versus in-tube solid-phase microextraction coupled to capillary liquid chromatography for the screening analysis of triazines in water samples.

This paper compares the advantages and disadvantages of two different configurations for the extraction of triazines from water samples: (1) on-fibre solid-phase microextraction (SPME) coupled to conventional liquid chromatography (LC); and (2) in-tube SPME coupled to capillary LC. In-tube SPME has been effected either with a packed column or with an open capillary column. A critical evaluation of the main parameters affecting the performance of each method has been carried out in order to select the most suitable approach according to the requirements of the analysis. In the on-fibre SPME configuration the fibre coating was polydimethylsiloxane (PDMS)-divinylbenzene (DVB). The limits of detection (LODs) obtained with this approach under the optimized extraction and desorption conditions were between 25 and 125 microg/L. The in-tube SPME approach with a C18 packed column (35 mm x 0.5 mm I.D., 5 microm particle size) connected to a switching micro-valve provided the best sensitivity; under such configuration the LODs were between 0.025 and 0.5 microg/L. The in-tube SPME approach with an open capillary column coated with PDMS (30 cm x 0.25 mm I.D., 0.25 microm of thickness coating) connected to the injection valve provided LODs between 0.1 and 0.5 microg/L. In all configurations UV detection at 230 nm was used. Atrazine, simazine, propazine, ametryn, prometryn and terbutryn were selected as model compounds.

Chromatography, Liquid↗

PubMed2006

An evaluation of solid phase microextraction for aliphatic amines using derivatization with 9-fluorenylmethyl chloroformate and liquid chromatography.

The reliability of SPME combined with a chemical reaction for the analysis of short-chain aliphatic amines by liquid chromatography has been investigated. Different options to couple SPME and derivatization have been tested and compared: (i) derivatization of the analytes in solution followed by the extraction of the derivatives, (ii) extraction of the analytes and subsequent derivatization by immersing the SPME fibre onto a solution of the reagent, and (iii) extraction/derivatization of the analytes using fibres previously coated with the reagent. Methylamine (MA), dimethylamine (DMA) and trimethylamine (TMA) have been selected as a model of primary, secondary and tertiary amines, respectively. The analytes have been derivatized with the fluorogenic reagent 9-fluorenylmethyl chloroformate (FMOC), and the fibre coating was Carbowax-templated resin (CW-TR). The employment of fibres coated with FMOC to extract and derivatize the analytes was the best option, as compared with the other approaches tested the sensitivity was considerably improved. On the basis of these studies, a new procedure for the determination of MA, DMA and TMA in water is presented. To demonstrate the utility of the proposed conditions data on linearity, accuracy, repeatability and sensitivity are given. Results of the determination of the amines in tap, river and waste water are also presented.

Amines↗

PubMed2005

Application of solid-phase microextraction combined with derivatization to the enantiomeric determination of amphetamines.

The utility of combining chiral derivatization and solid-phase microextraction (SPME) for the enantiomeric analysis of primary amphetamines by liquid chromatography has been investigated. Different derivatization/extraction strategies have been evaluated and compared using the chiral reagent o-phthaldialdehyde (OPA)-N-acetyl-l-cysteine (NAC) and fibres with a Carbowax-templated resin coating. Amphetamine, norephedrine and 3,4-methylenedioxyamphetamine (MDA) were used as model compounds. On the basis of the results obtained, a new method is presented based on the derivatization of the analytes in solution followed by SPME of the OPA-NAC derivatives formed. The proposed conditions have been applied to determine the compounds of interest at low ppm levels (<or=10 microg/ml) in aqueous and urine samples. Data on the linearity, reproducibility, sensitivity and selectivity are given. The utility of the described procedure for the quantification of amphetamine, norephedrine and MDA enantiomers in different kind of samples is also discussed.

Amphetamines↗

PubMed2004

Application of solid-phase microextraction combined with derivatization to the determination of amphetamines by liquid chromatography.

This work evaluates the utility of solid-phase microextraction (SPME) in the analysis of amphetamines by liquid chromatography (LC) after chemical derivatization of the analytes. Two approaches have been tested and compared, SPME followed by on-fiber derivatization of the extracted amphetamines, and solution derivatization followed by SPME of the derivatives formed. Both methods have been applied to measure amphetamine (AP), methamphetamine (MA), and 3,4-methylenedioxymethamphetamine (MDMA), using the fluorogenic reagent 9-fluorenylmethyl chloroformate (FMOC) and carbowax-templated resin (CW-TR)-coated fibers. Data on the application of the proposed methods for the analysis of different kind of samples are presented. When analyzing aqueous solutions of the analytes, both approaches gave similar analytical performance, but the sensitivity attainable with the solution derivatization/SPME method was better. The efficiencies observed when processing spiked urine samples by the SPME/on-fiber derivatization approach were very low. This was because the extraction of matrix components into the fiber coating prevented the extraction of the reagent. In contrast, the efficiencies obtained for spiked urine samples by the solution derivatization/SPME approach were similar to those obtained for aqueous samples. Therefore, the later method would be the method of choice for the quantification of amphetamines in urine.

Amphetamines↗