CE microchips: An opened gate to food analysis

Abstract

CE microchips are the first generation of micrototal analysis systems (-TAS) emerging in the miniaturization scene of food analysis. CE microchips for food analysis are fabricated in both glass and polymer materials, such as PDMS and poly(methyl methacrylate) (PMMA), and use simple layouts of simple and double T crosses. Nowadays, the detection route preferred is electrochemical in both, amperometry and conductivity modes, using end-channel and contactless configurations, respectively. Food applications using CE microchips are now emerging since food samples present complex matrices, the selectivity being a very important challenge because the total integration of analytical steps into microchip format is very difficult. As a consequence, the first contributions that have recently appeared in the relevant literature are based primarily on fast separations of analytes of high food significance. These protocols are combined with different strategies to achieve selectivity using a suitable nonextensive sample preparation and/or strategically choosing detection routes. Polyphenolic compounds, amino acids, preservatives, and organic and inorganic ions have been studied using CE microchips. Thus, new and exciting future expectations arise in the domain of food analysis. However, several drawbacks could easily be found and assumed within the miniaturization map.

Rapid analysis of azo‐dyes in food by microchip electrophoresis with electrochemical detection

“…Amperometric detection was performed with a 621A EC analyzer (CH Instruments, Austin, TX), using the "amperometric i-t curve" mode [40]. Sample injections were performed after stabilization of the baseline and electropherograms were recorded sampling current signals with a time resolution of 0.1 s, applying a detection potential of 21.0 V (vs. Ag/AgCl wire reference electrode).…”

“…These include the detection of sugars [34], phenolic acids [35], preservatives [36], natural antioxidants [37], vitamins [38], and triarylmethane dyes [39]. These and other applications of CE microchips for food analysis have been reviewed recently [40]. The potential integration of sample preparation steps (e.g., enrichment, cleanup, derivatization) with rapid separations and sensitive detection makes CE microchips particularly attractive for food analysis.…”

Portable capillary-based (non-chip) capillary electrophoresis

“…Chip-based CE (chip-CE) can be utilized in proteomic analysis [41], DNA separation, including sequencing [42][43][44], fragment sizing and genotyping [45], analysis of low-molecular-weight compounds (e.g., explosive residues and warfare agents) [46], food analysis [47], and analysis of pharmaceuticals, drugs and various analytes in body fluids [48]. Despite the trend towards increasing utilization of microfluidic chips in analytical chemistry, confirmed by the steadily growing number of scientific publications focusing on microfluidic chips (Fig.…”

Novas tecnologias para fabricação de microsistemas analíticos e detecção eletroquímica

“…Como discutido anteriormente, a detecção amperométrica "end-channel" também pode ser feita "off-chip", isto é, com o eletrodo de trabalho apenas alinhado e não integrado ao microdispositivo (Figura 3B). Esse tipo de configuração foi extensamente estudado por Wang e colaboradores, [47][48][49][50][51][52][53][54][55] usando principalmente eletrodos de carbono screen-printed, [47][48][49][50][51] na determinação de explosivos nitroaromáticos, [47] aminoácidos aromáticos, [48] selênio-aminoácidos, [49] fenóis, [50] entre outros. Quando comparado a integração do eletrodo no próprio dispositivo "on- eletrodos contruídos com nanotubos de carbono (CNTs), [53,54] [21,33] Lacher e colaboradores [57] recentemente descreveram a fabricação e otimização de um desacoplador em Pd totalmente integrado a um microdispostivo híbrido construído usando vidro e PDMS.…”

“…O uso da eletroforese em microdispositivos na análise de alimentos já foi previamente explorado na análise de várias classes de compostos, incluindo corantes sintéticos orgânicos, [22] compostos polifenólicos, amino ácidos, cátions e ânions inorgânicos, [49] mas esse é o primeiro trabalho envolvendo a determinação de azo-corantes.…”