Sulfite oxidase biosensors based on tetrathiafulvalene modified screen-printed carbon electrodes for sulfite determination in wine

Integrated all-solid-state sulfite sensors modified with two different ion-to-electron transducers: rapid assessment of sulfite in beverages

An integrated all-solid-state screen-printed ion-selective potentiometric sensor for rapid assessment of sulfite ion in beverages, based on analytical transduction, is described. The constructed potentiometric cell incorporates a polymeric membrane sulfite ion-selective electrode based on cobalt(ii) phthalocyanine (CoPC) as a recognition material and an Ag/AgCl reference electrode with a polyvinyl butyral reference membrane. Two different solid-contact transducers, namely multi-walled carbon nanotubes (MWCNTs) and polyaniline (PANI) were used for a comparative study. The presented sensors exhibited a rapid Nernst response across the concentration ranges from 2.0 × 10-6 to 2.3 × 10-3 M and from 5.0 × 10-6 to 2.3 × 10-3 M with detection limits equal to 1.1 × 10-6 M and 1.5 × 10-6 M for sensors based on MWCNTs and PANI, respectively. The proposed sensors manifested high selectivity and sensitivity, enhanced stability and low cost that provides a wide number of potential applications for food analysis. Good performance characteristics were obtained for the proposed method after applying the validation requirements. Method precision, accuracy, bias, trueness, repeatability, reproducibility, and uncertainty are examined. These analytical capabilities support the rapid and direct determination of sulfite in different beverage samples. The analytical results were verified and compared with the standard iodometric method.

Progress in Electrochemical (Bio)Sensors for Monitoring Wine Production

Electrochemical sensors and biosensors have been proposed as fast and cost effective analytical tools, meeting the robustness and performance requirements for industrial process monitoring. In wine production, electrochemical biosensors have proven useful for monitoring critical parameters related to alcoholic fermentation (AF), malolactic fermentation (MLF), determining the impact of the various technological steps and treatments on wine quality, or assessing the differences due to wine age, grape variety, vineyard or geographical region. This review summarizes the current information on the voltamperometric biosensors developed for monitoring wine production with a focus on sensing concepts tested in industry-like settings and on the main quality parameters such as glucose, alcohol, malic and lactic acids, phenolic compounds and allergens. Recent progress featuring nanomaterial-enabled enhancement of sensor performance and applications based on screen-printed electrodes is emphasized. A case study presents the monitoring of alcoholic fermentation based on commercial biosensors adapted with minimal method development for the detection of glucose and phenolic compounds in wine and included in an automated monitoring system. The current challenges and perspectives for the wider application of electrochemical sensors in monitoring industrial processes such as wine production are discussed.

A glassy carbon electrode modified by a triply-fused-like Co(ii) polyporphine and its ability for sulphite oxidation and detection

An original Co(ii) porphyrin conductive polymer is electrosynthesized which efficiently catalyzes sulphite oxidation in water offering opportunities for sensor development.

Flow injection analysis-flame atomic absorption spectrometry system for indirect determination of sulfite after on-line reduction of solid-phase manganese (IV) dioxide reactor

A new and simple flow injection method followed by atomic absorption spectrometry was developed for indirect determination of sulfite. The proposed method is based on the oxidation of sulfite to sulphate ion using solid-phase manganese dioxide (30% W/W suspended on silica gel beads) reactor. MnO₂ will be reduced to Mn(II) by sample injection in to the column under acidic carrier stream of HNO₃ (pH 2) with flow rate of 3.5mLmin^-1 at room temperature. Absorption measurement of Mn(II) which is proportional to the concentration of sulfite in the sample was carried out by atomic absorption spectrometry. The calibration curve was linear up to 25mgL^-1 with a detection limit (DL) of 0.08mgL^-1 for 400µL injection sample volume. The presented method is efficient toward sulfite determination in sugar and water samples with a relative standard deviation (RSD) less than 1.2% and a sampling rate of about 60h^-1.

Electrochemical Hydroxylation of C3-C12 n-Alkanes by Recombinant Alkane Hydroxylase (AlkB) and Rubredoxin-2 (AlkG) from Pseudomonas putida GPo1

An unprecedented method for the efficient conversion of C₃–C₁₂ linear alkanes to their corresponding primary alcohols mediated by the membrane-bound alkane hydroxylase (AlkB) from Pseudomonas putida GPo1 is demonstrated. The X-ray absorption spectroscopy (XAS) studies support that electrons can be transferred from the reduced AlkG (rubredoxin-2, the redox partner of AlkB) to AlkB in a two-phase manner. Based on this observation, an approach for the electrocatalytic conversion from alkanes to alcohols mediated by AlkB using an AlkG immobilized screen-printed carbon electrode (SPCE) is developed. The framework distortion of AlkB–AlkG adduct on SPCE surface might create promiscuity toward gaseous substrates. Hence, small alkanes including propane and n-butane can be accommodated in the hydrophobic pocket of AlkB for C–H bond activation. The proof of concept herein advances the development of artificial C–H bond activation catalysts.

Nanomaterials-based electrochemical detection of chemical contaminants

Recent advances in the development of nanomaterials-based electrochemical sensors for environmental monitoring and food safety applications are assessed.