Biomedical subjects

Carolina Simó

Publications and source records attributed to Carolina Simó.

22 records · Page 2Linked to original sources

PubMed2002

Evaluation of filter paper collection of urine samples for detection and measurement of organic acidurias by capillary electrophoresis.

There is little doubt that mental retardation has been prevented in most babies diagnosed by newborn screening programs for inborn errors and the cost-benefit ratios of these programs have been reported as highly positive. In a previous work we optimised a CE method for quick profiling of organic acidurias, which characterize a large number of inborn errors, so that it permits the separation, detection and even identification in less than 15 min of 22 organic acids in urine samples related to a wide range of metabolic disorders. In the present work we have studied the adequacy of filter paper collection of urine samples to simplify this step, always difficult in babies, when it is not performed by training personnel. The studied parameters were: media and conditions for re-extraction to give the best sensitivity and a more simple procedure when the samples are measured by CE, interferences coming from the diaper, recoveries obtained, possible correction of recoveries with creatinine and stability of the compounds. The whole method we report has the advantages of easy sample collection, easy shipping or delivery, and rapid analysis. Moreover, this method of collection and analysis allows the identification and quantitation of fumaric, methylmalonic, N-acetylaspartic, pyroglutamic and homogentisic acids, as well as glutaric acid for which screening is considered especially advisable.

Acids↗

PubMed2002

Analysis of antioxidants from orange juice obtained by countercurrent supercritical fluid extraction, using micellar electrokinetic chromatography and reverse-phase liquid chromatography.

Antioxidants from orange juice were determined by the combined use of countercurrent supercritical fluid extraction (CC-SFE) prior to reverse-phase liquic chromatography (RP-LC) or micellar electrokinetic chromatography (MEKC). The separation of antioxidants found in the SFE fractions was achieved by using a new MEKC method and a published LC procedure, both using diode array detection. The characterization of the different antioxidants was further done by LC-mass spectrometry. Advantages and drawbacks of LC and MEKC for analyzing the antioxidants found in the different orange extracts are discussed. Although LC yields higher peak area and slightly better reproducibility than MEKC, the latter technique provides information about the CC-SFE extracts in analysis times 7 times faster than by LC. This analysis advantage can be used for the quick adjustment of CC-SFE conditions, thus providing a fast way to obtain orange fractions of specific composition.

Antioxidants↗

PubMed2002

Sensitive micellar electrokinetic chromatography-laser-induced fluorescence method to analyze chiral amino acids in orange juices.

In this work a new method to detect the existence of chiral amino acids in orange juice is presented. The method employs beta-cyclodextrins and micellar electrokinetic chromatography with laser-induced fluorescence (MEKC-LIF) to separate and detect L- and D-amino acids (L-aa and D-aa) previously derivatized with fluorescein isothiocianate (FITC). A systematic optimization of the chiral-MEKC conditions is done bringing about in less than 20 min a good separation of the main amino acids found in orange juice (i.e., Pro, Asp, Ser, Asn, Glu, Ala, Arg, and the nonchiral GABA, i.e., gamma-aminobutyric acid). Using this procedure, the analysis time reproducibility for the 15 standard compounds (L-aa, D-aa, and GABA) has been determined to be better than 0.2% (n = 5) for the same day and better than 0.7% (n = 15) for three different days. Corrected peak area reproducibility is somewhat lower, providing values better than 3.3% (n = 5) for the same day and 6.9% (n = 15) for three different days. The limit of detection using this procedure was determined to be 0.86 attomoles for L-Arg. The optimized FITC derivatization method allows the easy and straightforward detection of amino acids in orange concentrates and juices (i.e., only centrifugation of diluted samples for 5 min is needed prior to their derivatization). D-Ala, D-Asp, D-Arg, and D-Glu were determined in orange juices and orange concentrates from different geographical origins using this new method. Moreover, the effect of different temperature treatments (50, 92, and 150 degrees C) on the content of D-aa in orange juice was evaluated.

Amino Acids↗

PubMed2002

Simulation and optimization of peptide separation by capillary electrophoresis-mass spectrometry.

The potential of capillary electrophoresis (CE) for the separation of peptides has been extensively demonstrated in the last decade. Their correct characterization and sequenciation is a difficult task that can be accomplished using CE-mass spectrometry (CE-MS). An important limitation of CE-MS is the buffer choice since it should provide an adequate CE separation without ruining the MS signal. In this work, a new strategy is used to help to solve this limitation based on the combination of two different methodologies. Namely, an ab initio semiempirical model that relates electrophoretic behavior of peptides to their sequence is first used to obtain in a fast and easy way adequate CE buffers compatible with MS analysis. Next, CE-MS is used to separate and characterize peptides via the determination of their relative molecular masses. The usefulness of this procedure is demonstrated analyzing in a single CE-MS run a group of 10 standard peptides of very different nature (i.e., relative molecular masses ranging from 132 to 1037 and isoelectric points ranging from 5.69 to 10.62). It is concluded that the use of this strategy can help to overcome the buffer limitation in CE-MS.

Amino Acid Sequence↗