Ion-transfer voltammetric determination of folic acid at meso-liquid–liquid interface arrays

Abstract

Voltammetric studies on the simple ion transfer (IT) behaviors of an important water-soluble B-vitamin, folic acid (FA), at the liquid-liquid (L-L) interface were firstly performed and then applied as a novel detection method for FA under physiological conditions. Meso-water-1,6-dichlorohexane (W-DCH) and meso-water-organogel interface arrays were built by using a hybrid mesoporous silica membrane (HMSM) with a unique structure of pores-in-pores and employed as the new platforms for the IT voltammetric study. In view of the unique structure of the HMSM, the impact of the ionic surfactant cetyltrimethylammonium bromide (CTAB), self-assembled within the silica nanochannels of the HMSM, was investigated. In particular, its effect on the IT voltammetric behavior and detection of FA at meso-L-L interface arrays was systematically examined by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and differential pulse stripping voltammetry (DPSV). It was found that all the voltammetric responses of CV, DPV, and DPSV and the corresponding detection limit of FA at such meso-L-L interface arrays are closely related to the CTAB in the HMSM. Significantly, the calculated detection limit of FA could be improved to 80 nM after the combination of the DPSV technique with the additional preconcentration of FA in the silica-CTAB nanochannels, achieved through an anion-exchange process between FA(-) and the bromide of CTAB in HMSM. This provides a new and attractive strategy for the detection of those biological anions.

Decorating soft electrified interfaces: From molecular assemblies to nano-objects

“…This ex situ silica modified membrane supported the ITIES and was used to study the ion transfer of TEA + , K + and of organic anion assisted by cytochrome c. Among all three studied species only the ion transfer associated with cytochrome c was suppressed as the average silica mesopore diameter was estimated to be 3 nm which is enough for macromolecular sieving. A membrane modified in a similar manner was used as a liquidliquid based electrochemical sensor for the folic acid detection [196]. Figure 10.…”

“…This can be achieved with inorganic materials in a form of a membrane e.g. mesoporous silica [42,196,198,199] or zeolite [190,192] materials that can affect size and charge screening properties of the ITIES. For the former the ionic transport is affected by the confined size of the pores within the membrane framework whereas for the latter it is the membrane surface charge governed by ionisable functionalities that can electrostatically interact with transferring ions.…”

Local pH changes triggered by photoelectrochemistry for silica condensation at the liquid-liquid interface

“…nanoparticles or membranes) synthesised ex-situ. Membranes prepared ex-situ have been used for size or charge selectivity [3][4][5] or improved sensitivity [6][7][8]. Senthilkumar et al synthesised a zeolite Y, which modified the interface and presented both size exclusion of tetrabutylammonium cations and charge exclusion of tetrafluoroborate and perchlorate anions [3].…”

“…Senthilkumar et al synthesised a zeolite Y, which modified the interface and presented both size exclusion of tetrabutylammonium cations and charge exclusion of tetrafluoroborate and perchlorate anions [3]. Chen and colleagues prepared mesoporous silica supported by a polyethylene terephthalate membrane [9], which was then used for the detection of folic acid at the ITIES [5]. Sensitivity of electroanalysis at the ITIES was improved by the use of regularly aligned ITIES of micro- [6,7] or nanoscopic dimensions [8] supported by polymeric [6] or silicon membranes [7,8].…”

Electroanalytical Opportunities Derived from Ion Transfer at Interfaces between Immiscible Electrolyte Solutions

“…Employing a preconcentration step (90 s) for folic acid at such silica-ionic surfactant nanochannels allowed the detection of 80 nM folic acid via DPSV. [56] …”