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HighlightsAn analytical methodology based on DLLME-LIBS combination is presented. This method is aimed to improve sensitivity of LIBS in liquids analysis. DLLME-LIBS resulted more efficient than SDME-LIBS for enhancing LIBS sensitivity. t r a c tA rapid and efficient Dispersive Liquid-Liquid Microextraction (DLLME) followed by Laser-Induced Breakdown Spectroscopy detection (LIBS) was evaluated for simultaneous determination of Cr, Cu, Mn, Ni and Zn in water samples. Metals in the samples were extracted with tetrachloromethane as pyrrolidinedithiocarbamate (APDC) complexes, using vortex agitation to achieve dispersion of the extractant solvent. Several DLLME experimental factors affecting extraction efficiency were optimized with a multivariate approach. Under optimum DLLME conditions, DLLME-LIBS method was found to be of about 4.0-5.5 times more sensitive than LIBS, achieving limits of detection of about 3.7-5.6 times lower. To assess accuracy of the proposed DLLME-LIBS procedure, a certified reference material of estuarine water was analyzed.

Childhood obesity is a major worldwide health problem. Intervention programs to ameliorate the rate of obesity have been designed and implemented; yet the epidemic has no end near in sight. AMP-activated protein kinase (AMPK) has become one of the most important key elements in energy control, appetite regulation, myogenesis, adipocyte differentiation, and cellular stress management. Obesity is a multifactorial disease, which has a very strong genetic component, especially epigenetic factors. The intrauterine milieu has a determinant impact on adult life, since the measures taken for survival are kept throughout life thanks to epigenetic modification. Nutrigenomics studies the influence of certain food molecules on the metabolome profile, raising the question of an individualized obesity therapy according to metabolic (and probably) genetic features. Metformin, an insulin sensitizing agent, its known to lower insulin resistance and enhance metabolic profile, with an additional weight reduction capacity, via activation of AMPK. Exercise is coadjutant for lifestyle modifications, which also activates AMPK in several ways contributing to glucose and fat oxidation. The following review examines AMPK's role in obesity, applying its use as a tool for childhood and adolescent obesity.

In this work, on-line calibration methods were applied for compensation for matrix effects in Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) using three novel multiple sample introduction systems based on Flow Blurring Ò technology. The methods were compared with conventional calibration methods, using a Conikal nebulizer and a cyclonic spray chamber (i.e., Standard Sample Introduction (SSI) system). Experiments were carried out with synthetic samples containing different matrices. The total liquid flow through the multinebulizers was 400 mL min À1 whereas in the SSI system it was 1000 mL min À1 . One type of calibration method tested was external calibration. By using this calibration method, the mean of absolute values corresponding to the relative error values of different multiple sample introduction systems and all the matrices was 14% and uncertainty was 0.6%. When on-line internal standard calibration was used, the mean relative error value dropped to 3% and uncertainty was 0.6%. With on-line standard addition calibration, relative error values went down to 2%. However, uncertainty values increased to 2% in all cases. With all the calibration methodologies, the accuracy and uncertainty of the obtained results were very similar for both standard and multiple sample introduction systems. The main difference was a significant reduction in resource consumption (i.e., samples, reagents and time) when multinebulization systems were used. Sensitivity, precision and limits of detection were evaluated for the different Flow Blurring Ò based systems and SSI system. For most of the emission lines evaluated, all the Flow Blurring Ò based systems gave higher precision values and lower limits of detection than SSI system. A certified reference material (Estuarine Water, LGC6016), without prior sample treatment (i.e., dilution), was analyzed using external calibration with the SSI system and on-line standard addition calibration with Flow Blurring Ò based systems. The certified reference material analysis gave relative error values ranging between +20% and À30% for the SSI system, and between +4% and À2% for Flow Blurring Ò based systems.

15In this work, an analytical methodology based on Single Drop Microextraction (SDME) 16 followed by Laser-Induced Breakdown Spectrometry (LIBS) has been tested for trace metals 17 determination in liquid samples. By this method, analytes in the samples were extracted into a 18 small volume of toluene as ammonium pyrroldinedithiocarbamate (APDC) chelates. After 19 that, the analyte-enriched toluene was dried on a solid substrate and, finally, the resulting 20 solid residue was analyzed by LIBS. Analyte extraction by SDME procedure was firstly 21 optimized by using a multivariate optimization approach. Under optimum SDME conditions, 22analytical figures of merit of the proposed SDME-LIBS methodology were compared to 23 those of the direct LIBS analysis method (i.e., without SDME procedure). An estuarine water 24 certified reference material was analyzed for method trueness evaluation. The results 25obtained in this study indicate that SDME-LIBS methodology leads to a sensitivity increase 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59

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We demonstrate a rapid and ultrasensitive assay for protein quantification through the nanoparticle–photonic crystal coupling embedded in microfluidic cartridges.

A novel multinebulizer allows a high mixing efficiency between two liquids, since the mixing takes place under turbulent conditions.