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Rios A.,University of Castilla - La Mancha | Rios A.,Regional Institute for Applied Chemistry Research | Zougagh M.,Regional Institute for Applied Chemistry Research
TrAC - Trends in Analytical Chemistry | Year: 2013

The integration of sample treatment into a micro total analytical system (μ-TAS) represents one of the remaining hurdles towards achieving truly miniaturized systems. The challenge is made more complex by the enormous variation in samples to be analyzed. Moreover, the pretreatment technique has to be compatible with the analytical device to which it is coupled, in terms of time, reagent and power consumption, and sample volume.This review, with more than 140 references, presents some recent advances and novel strategies for sample preparation in μ-TASs. We classify μ-TAS sample-preparation methods according to the mechanism that links the analyte(s) of interest to substrates: filtration, cell lysis, liquid-liquid extraction, solid-phase extraction, droplet membrane droplet, treatment by nanomaterials, stacking and isotachophoresis. We compare these techniques in terms of sample flexibility, arguing for these applications in some fields, such as biological and environmental. These discussions can help to determine the appropriate sample-preparation technique for generating a true μ-TAS. We provide a critical discussion and some key conclusions. © 2012 Elsevier Ltd. Source


Rios A.,University of Castilla - La Mancha | Rios A.,Regional Institute for Applied Chemistry Research | Zougagh M.,Regional Institute for Applied Chemistry Research | Avila M.,University of Castilla - La Mancha
Analytica Chimica Acta | Year: 2012

Micro total analysis (μTAS), also called " lab-on-a-chip (LOC)" technology, promises solutions for high throughput and highly specific analysis for chemistry, biology and medicine, while consuming only tiny amounts of samples, reactants and space. This article reports selected contributions of LOC, which represent clear practical approaches for routine work, or presenting potentiality to be transferred to routine analytical laboratories. Taking into account the present LOC state-of-the-art, we identify various reasons for its scarce implementation in routine analytical laboratories despite its high analytical potential, as well as the probably main " niche" for successfully practical developments is suggested. © 2012 Elsevier B.V.. Source


De Andres F.,University of Castilla - La Mancha | Zougagh M.,University of Castilla - La Mancha | Castaneda G.,University of Castilla - La Mancha | Rios A.,University of Castilla - La Mancha | Rios A.,Regional Institute for Applied Chemistry Research
Analytical and Bioanalytical Chemistry | Year: 2010

A rapid and simple method for separation and detection of six heterocyclic aromatic amines (2-amino-1-methyl-6-phenylimidazo [4,5-b]-pyridine, 2-amino-1-methyl-imidazo [4,5-f]-quinoline, 2-amino-3,8-dimethyl-imidazo [4,5-f]-quinoxaline, 2-amino-3,7,8-trimethyl-imidazo [4,5-f]-quinoxaline, 2-amino-3,4,8-trimethyl-imidazo [4,5-f]-quinoxaline, and 2-amino-3,4-dimethyl- imidazo [4,5-f]-quinoline) in human urine samples is proposed to reflect daily intake and recent HAAs exposure. This method comprises previous clean-up and preconcentration of the analytes on Strata-X reversed phase extraction cartridges followed by capillary liquid chromatography (CLC) and evaporative light-scattering detection (ELSD). A mobile phase of acetonitrile and ammonium acetate 35 mM at pH 5.15 through a gradient of composition and a flow rate of 15 μL min-1 resulted in good separations of the analytes. Temperature and gas pressure were optimized for detection. The CLC-ELSD allows the separation and quantification of HAAs with good resolution, precision, and sensitivity. The usefulness of the proposed method was demonstrated by the analysis of synthetic and natural human urine samples spiked with different concentration levels of heterocyclic amines. © 2010 Springer-Verlag. Source


Bouri M.,University of Castilla - La Mancha | Salghi R.,Ecole Nationale de science Appliquees | Zougagh M.,Regional Institute for Applied Chemistry Research | Rios A.,University of Castilla - La Mancha | Rios A.,Regional Institute for Applied Chemistry Research
Electrophoresis | Year: 2013

An improved and efficient method for the determination of underivatized amino acids based on the use of CE coupled to evaporative light scattering detector (ELSD), involving carbon nanotubes, was successfully developed. Carboxyled single-walled carbon nanotubes were used for the first time to perform the clean-up of the analyzed samples, which were afterwards analyzed by CE-ELSD. White tea samples were used to demonstrate the usefulness of the CE-ELSD coupled methodology. A suitable interface, based on a triple tube design sprayer, was developed and successfully used for coupling both instruments. Parameters affecting the separation and determination, including the elimination of interferences, were studied and properly optimized. Under the optimized conditions good resolution was achieved for the separation of seven amino acids. The precision of the method, expressed as RSD, was found within the 3.5-5.3% range. The LOD obtained for the proposed method were in the 1.2-2.1 pg range and the LOQ, were in the 2.0-11.5 pg range, with injection pressure of 5 KPa for 20 s (15.3 nL). This method is simple, rapid, and selective compared with other conventional techniques. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Rios A.,University of Castilla - La Mancha | Zougagh M.,Regional Institute for Applied Chemistry Research | Zougagh M.,University of Castilla - La Mancha
TrAC - Trends in Analytical Chemistry | Year: 2016

The recent advances involving the use of magnetic nanomaterials for improving different steps of analytical processes were revised. Magnetic nanomaterials are unique tools for the simplification of the sample preparation working under a solid phase (micro)extraction format, in order to provide the appropriated selectivity (clean-up) and sensitivity (preconcentration) of many new analytical methods, or improving this step in already existing ones. In addition, magnetic nanomaterials can play a key role for the separation processes (chromatographic or electrophoretic), in which some analytical methods are based. The third interesting incidence of magnetic nanomaterials are in the detection step, showing new advantageous possibilities. All these aspects are revised in this article. © 2016 Elsevier B.V. Source

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