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The well-known complexity of food matrices is approached using CE microchips with different strategies to improve the selectivity and sensitivity of the analysis by avoiding and/or making the sample preparation as simple as possible: (i) enhancing the peak capacity in order to perform direct injection, (ii) using the microchip platform to measure one target analyte/group of analytes with or without separating other related interferences, (iii) integrating sample preparation steps on the microchip platform, and (iv) integrating new analytical tools from nanotechnology in the detection stage. New analyte separations of food significance involving DNA probes, biogenic amines, vanilla flavors, and dyes have been reported as successfully breaking new barriers in areas of high impact in the market, such as transgenic food analysis, as well as the detection of frauds and toxins. Simple microchip layouts are still the most common designs used, though sophisticated new ones are emerging. In contrast to other application areas, electrochemical detection continues to be the most common detection route, followed by LIF, though non-conventional detection routes are also emerging, such as chemiluminescence or UV. In terms of analytical performance, the integration of calibration and quality control on a microchip platform, and remarkable accuracy and precision are being obtained using creative analytical methodologies that enhance the analytical potency of microfluidic chips for their future commercialization. This review critically states the most important advances derived from work done in the field over the past 2-3 years.

A novel analytical strategy that couples enzyme-linked immunosorbent assay (ELISA) and electrochemical microfluidic chips to determine the mycotoxin zearalenone (ZEA) in baby foods is presented. The analytical cycles for an ultra-fast analysis of the sample and its sequential fast and simplified calibration were performed in about 200 s plus to ELISA protocol. This route avoided the typical four-parameter logistic curve fit which is a highly time-consuming and laborious procedure. An extremely low concentration level of ZEA (less than 1 ppb) was detected with reliability. This level is 20 times lower than the strictest tolerable limit (20 ppb) for baby foods, making the microfluidic approach the newly anticipated analytical security tool for the future. The reliability of the proposal was demonstrated by accuracy evaluations using a certified reference material and by demonstrating its suitability during the control of the regulatory limits of ZEA in baby foods. In addition, the microfluidic approach allowed sensitivity and the incubation enzymatic reaction to be manipulated in situ.

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The accuracy of a novel electroanalytical route to determine total isoflavones using a secondary standard from Drug Master File (SW/1211/03) as metrological reference with well-known traceability and its applicability using representative soy samples is demonstrated. Calibration protocols were used i) for choosing a suitable isoflavone standard to determine the total isoflavone content, ii) to evaluate matrix effects and, iii) to evaluate the overall reliability and performance of the method in analytical operations, extraction and analysis. The inherent electroactivity of both, aglycones and glycoside structures and the similar analytical sensitivity exhibited by the prominent soy isoflavones was relevant to determine the total amount with reliability in terms of accuracy (E < 10%) and precision (RSDs < 7%) in soy samples. In consequence, the introduction of the term isoflavonoid index as the total amount of isoflavones obtained when they are amperometrically monitorized at þ 1.0 V as a particular case of the electrochemical index concept is proposed. In addition, since spectrophotometric protocol overestimated the total isoflavones content in samples where only isoflavones are present, this work demonstrates clearly the accuracy of the "Electrochemical Index" concept.