A fast and reliable route integrating calibration and analysis protocols for water‐soluble vitamin determination on microchip‐electrochemistry platforms

Abstract

A novel analytical route to determine water-soluble vitamins (B group and C) using single channel microchip-electrochemistry platforms is presented. The electrochemical detection protocol was carefully optimized, and it was shown that it was crucial to use 1 M nitric acid in the detector compartment to detect folic acid. A phosphate buffer (pH 6, 10 mM) and a separation voltage of 2 kV gave the complete separation of vitamins in less than 130 s, with good reproducibility (RSDs less than 10%) and accuracy (error less than 9%). In addition, a methodological innovation integrating calibration and analysis of water-soluble vitamins on the chip is also proposed. The strategy consisted in sequentially using both reservoirs (named calibration and analysis reservoirs) as well as a calibration factor (defined as signal/concentration of analyte). The analytical route required 350 s in the overall protocol (employing 130 s in calibration plus 130 s in analysis), an improvement over the times used in both conventional and microchip protocols.

Carbon nanotube disposable detectors in microchip capillary electrophoresis for water‐soluble vitamin determination: Analytical possibilities in pharmaceutical quality control

“…Indeed, while no significant differences for ascorbic acid were observed, an important improvement of the LOD for pyridoxine from 29 to 8 micromolar was clearly noticed. This fact was notably important since the electrochemical behavior of this vitamin becomes complex in previous works [20]. Precision was also thoroughly studied for both repeatability and reproducibility with the same electrode.…”

“…To solve this handicap, an integration concept of calibration and quantitative determination previously proposed [20] has been adapted to this analysis when the new detectors were used since zero was present in the confidence interval of the intercept (see Table 2). The analytical injection protocol used in this work to integrate the analysis of the samples and the calibration (control of quality) was as follows: the vitamin sample is electrokinetically loaded from one reservoir for 5 s and sequentially a standard mixture is electrokinetically loaded from the another reservoir to obtain a calibration factor (defined as signal/concentration standard) with quality control purposes (see Fig.…”

“…The adapted CE-ED microsystem used in this paper is described elsewhere [20]. The glass chip was fabricated by Micralyne (Model MC-BF4-001, Edmond, Canada) and consisted of a glass plate (88 mm616 mm) with a four-way injection cross, a 74 mm long separation channel, and side arms measuring 5 mm long.…”

“…Water-soluble vitamin supplements are widely used in therapeutics to supply the very common lack of vitamins due to their high impact on our health. Previously, we have demonstrated the suitability of CE microchips in the determination of these analytes versus highly time-consuming and nonenvironmentally friendly protocols such as RP HPLC [20]. In this paper, we explore the use of CNTs as electrochemical detectors in CE microchips modifying two kinds of carbon electrodes (glassy carbon electrode (GCE) and screen-printed carbon electrode) with the objective of increasing the sensitivity, reducing the LOD, and improving the electrode stability; so, finally, the analytical possibilities of these microsystems could be amplified.…”

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

“…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].…”