A novel electroanalytical approach to the measurement of B vitamins in food supplements based on screen-printed carbon sensors

Abstract

This paper describes the development of a novel electrochemical assay for the measurement of water-soluble vitamins in food and pharmaceutical products. The optimum conditions for the determination of vitamin B (thiamine), B (riboflavin) and B (pyridoxine) in phosphate buffer were established using cyclic voltammetry in conjunction with screen printed carbon electrodes (SPCEs). The optimum current response for all three vitamins was achieved in 0.1M phosphate buffer pH 11 using an initial potential of -1.0V. Using square wave voltammetry, the linear ranges for thiamine, riboflavin, and pyridoxine were found to be: 15-110µg/ml, 0.1-20µg/ml, and 2-80µg/ml respectively. The application of the method to a commercial food product yielded a recovery of 95.78% for riboflavin, with a coefficient of variation (CV) of 3.38% (n = 5). The method was also applied to a multi-vitamin supplement for the simultaneous determination of thiamine, riboflavin and pyridoxine. In both cases only simple dilution with buffer followed by centrifugation was required prior to analysis. The resulting square wave voltammetric signals were completely resolved with Ep values of -0.7V, +0.2V, and +0.6V respectively. The recoveries determined for the vitamin B complex in a commercial supplement product were found to be 110%, 114%, and 112% respectively (CV = 7.14%, 6.28%. 5.66% respectively, n = 5).

An Electrocatalytic Screen-Printed Amperometric Sensor for the Selective Measurement of Thiamine (Vitamin B1) in Food Supplements

“…There also appears to be the beginning of a second oxidation response from +0.15 V vs. Ag/AgCl, which would suggest direct oxidation of thiamine at the plain carbon surface. This is consistent with our previous observations using a plain SPCE in conjunction with voltammetry [8].…”

“…As previous studies [8,20] had shown that vitamin B1 was electroactive under alkaline conditions using a plain SPCE, we initially carried out a cyclic voltammetric study using a CoPC-SPCE sensor with a solution containing vitamin B1 in phosphate buffer pH 12, containing 0.1 M sodium chloride. Figure 1 shows the resulting cyclic voltammogram (A), which exhibits a well-defined peak at a potential of −0.013 V vs. Ag/AgCl; whereas the peak potential obtained with a plain SPCE (B) was +0.34 V. Clearly, the incorporation of the metallic electrocatalyst into the SPCE resulted in a reduction of the peak potential from +0.34 V to −0.013 V for the anodic peak.…”

“…An electrochemical approach using sensors based on a plain screen-printed carbon electrode for the measurement of B1 in food supplements was successfully developed by our group [8]. We have regularly selected screen-printing technology as the platform for our biosensor fabrication as it facilitates their construction in a wide range of geometries; in addition, it allows for mass production at low cost, consequently, they can be considered disposable.…”

“…We have regularly selected screen-printing technology as the platform for our biosensor fabrication as it facilitates their construction in a wide range of geometries; in addition, it allows for mass production at low cost, consequently, they can be considered disposable. In the present study, the authors explored the possibility of improving the sensitivity and selectivity of their previous assay [8] by the inclusion of an electrocatalyst in the carbon ink with the aim of determining vitamin B1 at both low and high concentrations in complex matrices. In previous studies, we demonstrated that a range of sulphur-containing compounds could be determined using a sensor comprised of a screen-printed carbon electrode containing the electrocatalyst cobalt phthalocyanine (CoPC-SPCE).…”

Electrochemical performance of activated screen printed carbon electrodes for hydrogen peroxide and phenol derivatives sensing

“…They allowed the replacement of traditional beaker-type electrochemical cells with easy-to-use sensors that support the analysis of microvolumes of samples [2]. For all these reasons, SPEs have attracted considerable attention in recent years, with a plethora of applications in not only fundamental research [3,4], and clinical [5], environmental [2] and food analyses [6][7][8], but also in teaching [9,10].…”