Determination Of Sulfite In Wine Research Articles

Development of a portable electroanalytical methodology for determination of sulfite in wine using screen-printed carbon electrodes modified with carbon nanotubes

This study describes the development of an electroanalytical methodology applying square wave voltammetry (SWV) to quantify sulfite in wine using a portable system associated with screen-printed carbon electrodes modified with carboxyl functionalized multi-walled carbon nanotubes (SPCE MWCNT-COOH). SWV parameters were optimized using the design of experiments in 0.100 mol L−1 phosphate buffer at pH 4.00 as supporting electrolyte. The sulfite agents showed an oxidation peak around 0.700 V, which corresponds to the species HSO3−, and values of the limit of quantitation and detection of 4.99 × 10−5 and 1.65 × 10−5 mol L−1, respectively, in the linear range of 5.00 × 10−6 to 8.00 × 10−4 mol L−1, and R2 equal to 0.997. The method did not show interference between common molecules found in wine. Furthermore, wine samples were analyzed by the proposed technique and compared with the Brazilian official method (iodometric titration). There was no significant difference between the sulfite concentrations obtained in both procedures. These results show that the proposed methodology is promising for monitoring sulfite agents, employing a low amount of sample per analysis, and the possibility of applying the sulfite determination in loco.

Determination of Sulfite in Wine Using Differential Pulse Polarography

Sulfite determination plays an important role, since it is used in some food stuff as protecting agent. It is a known fact that higher values of sulfite in foods will create some health problems. Thus, its accurate determination has a vital importance. In this investigation a new and simple DP polarographic method is established for the determination of sulfite. The polarographic peak of sulfite was used for its determination. The polarograms of sulfite were taken in various electrolytes and pH values in the presence or absence of wine in order to find the best working conditions. It was possible to determine 2 × 10–6 M sulfite in pH 4 Hac–NaAc electrolyte. This method is applied to various wines and it was possible to determine the free and bound sulfite. The results obtained were also compared with an iodometric method used in TSE (Turkish standardization Institute).

Potentiometric sulfite biosensor based on entrapment of sulfite oxidase in a polypyrrole film on a platinum electrode modified with platinum nanoparticles

The surface of a platinum electrode has been modified with platinum nanoparticles (PtNPs) and the enzyme sulfite oxidase (SOx), was entrapped on its surface in an ultrathin polypyrrole (PPy) film. The PtNPs, with a diameter of 30–40 nm, were deposited on the Pt electrode by cycling the electrode potential 20 times from -200 to 200 mV at a sweep rate of 50 mV.s-1. Morphological evidence of the successful incorporation of SOx and the presence of PtNPs were obtained by scanning electron microscopy. Also, the electrochemical behavior of the PtNPs/PPy-SOx film was examined by cyclic voltammetry, chronopotentiometry, electrochemical impedance spectroscopy and potentiometry. Under optimized conditions, the biosensor achieved a sensitivity of 57.5 mV.decade-1, a linear response that extends from 0.75 to 65 μM of sulfite, a detection limit of 12.4 nM, and a response time of 3–5 s. The biosensor was successfully applied to the determination of sulfite in wine and beer samples.

A gas-diffusion microfluidic paper-based analytical device (μPAD) coupled with portable surface-enhanced Raman scattering (SERS): facile determination of sulphite in wines.

A novel facile method for on-site determination of sulphite in wine using a gas-diffusion microfluidic paper-based analytical device (μPAD) combined with surface-enhanced Raman spectroscopy (SERS) was explored. The inexpensive and disposable μPAD was realized by sandwiching the ZnO-paper disc and integrating gas-diffusion separation and gas preconcentration on a paper-based platform. Through extensive condition optimization, the SERS signal at a shift of 620 cm(-1) and the concentration of SO2 showed good linearity in the range of 5-300 μg mL(-1). The linear correlation coefficient was 0.995 and the detection limit for sulphite was found to be 2 μg mL(-1). Ultimately, this proposed method was applied to the determination of sulphite in wine, which can be essentially paralleled with the official method. Endowed with portability, minimal reagent consumption, and operational simplicity, this developed device would find broad utilization for on-site monitoring of sulphite.

Determination of sulphite in wines using suppressed ion chromatography

Suppressed ion chromatography with the use of a conductivity detector was developed for the determination of sulphite ions in wine samples. When a mixed solution of sodium carbonate, sodium bicarbonate, and acetone was used as the mobile phase, simultaneous determination of eight inorganic anions (i.e., fluoride, chloride, nitrite, nitrate, sulphite, phosphate, sulphate, and thiosulphate) was completed in approximately 25min. Linearity, reproducibility, and detection limits were determined for the proposed method. In the case of sulphite detection, a linear calibration curve with a good correlation coefficient of 0.9992 was obtained from the peak height of sulphite with a relative standard deviation (n=6) 1.48%. In addition, the detection limit of sulphite was 0.27mg/L at a signal-to-noise ratio of 3. Further, the developed method was applied for the determination of sulphite contained in several wine samples.

Sensor for Quantitative Analytical Determination of Sulphite in Wine Using a System of Modified Electrode and a Membrane Absorption System

In this work we present the comparison among three glassy carbon electrodes modified by Co-porphyrin (CoTAPP), ortho-phenylendiamine (OPD), or both, simultaneously. This comparison shows the differences among their electrochemical behavior and their electrocatalytic behavior toward the oxidation of sulfite. In the case of the glassy carbon modified electrodes, the presence of the copolymer enhances the electrocatalytic performance of the modified electrodes in spite of the non-catalytic response (compared to the bare glassy carbon) of both homopolymers-modified electrodes toward the oxidation of sulfite. Also, the oxidation of sulfite extracted from red wine is showed. The copolymer-modified electrode is capable of oxidizing the extracted free sulfite in a 0.02 M NaOH solution. Through the addition of standards method, a concentration of 44 ppm for free sulfite is found in a Chilean red wine.

Sensor for Quantitative Analytical Determination of Sulphite in Wine Using a System of Modified Electrode and a Membrane Absorption System

The sulfite is commonly used antiseptic wine and food. You can find free or bound to phenols , aldehydes and other organic compounds. Its concentration at high levels produces toxic effects, such as pain when breathing in asthmatic patients , hypotension and gastrointestinal problems. Therefore it is useful to determine the electrochemically concentration , and with this, to separate , by absorbing membrane system , the other impurities present in food. Sulfite (SO3 -2) in aqueous solution is in equilibrium with bisulfite ( HSO3 - ) and sulfur dioxide ( SO2) , where their concentrations depend mainly on the pH. As to the electrochemical method , the cyclic voltammetry was used. This technique is widely used and is of considerable use in the study of oxide / reduction , detection of reaction intermediates and observing reactions monitoring electrode products formed in reactions . In conjunction with the cyclic voltammetry method of calibration curve is applied and thus determine how feasible it is to implement in an electrochemical analysis. The method of calibration curve represents the response of an analytical method to known concentrations of analyte . Previous studies done in the laboratory show that it is possible to find a potential range where the SO3 -2 shows an increasing response in current and potential displacement , and in addition, all the parameters are optimized for system performance membrane absorber .

Rapid flow injection method for the determination of sulfite in wine using the permanganate–luminol luminescence system

A simple, rapid and sensitive chemiluminescence method for the determination of sulfite has been developed by combining flow-injection analysis and its sensitizing effect on the known chemiluminescence emission produced by the oxidation of luminol in alkaline medium; in this work permanganate has been proposed as oxidizing reactive. The optimum conditions for the chemiluminescence emission were established. The chemiluminescence was proportional to the sulfite concentration over the range 1.6 × 10 −5 and 4.0 × 10 −4 mol L −1. The detection limit was 4.7 × 10 −6 mol L −1 of sulfite. The method has been satisfactorily used for the determination of free and bound sulfite in wines.

Amperometric Determination of Sulfite by Gas Diffusion- Sequential Injection with Boron-Doped Diamond Electrode.

A gas diffusion sequential injection system with amperometric detection using aboron-doped diamond electrode was developed for the determination of sulfite. A gasdiffusion unit (GDU) was used to prevent interference from sample matrices for theelectrochemical measurement. The sample was mixed with an acid solution to generategaseous sulfur dioxide prior to its passage through the donor channel of the GDU. Thesulfur dioxide diffused through the PTFE hydrophobic membrane into a carrier solution of 0.1 M phosphate buffer (pH 8)/0.1% sodium dodecyl sulfate in the acceptor channel of theGDU and turned to sulfite. Then the sulfite was carried to the electrochemical flow cell anddetected directly by amperometry using the boron-doped diamond electrode at 0.95 V(versus Ag/AgCl). Sodium dodecyl sulfate was added to the carrier solution to preventelectrode fouling. This method was applicable in the concentration range of 0.2-20 mgSO32-/L and a detection limit (S/N = 3) of 0.05 mg SO3²-/L was achieved. This method wassuccessfully applied to the determination of sulfite in wines and the analytical resultsagreed well with those obtained by iodimetric titration. The relative standard deviations forthe analysis of sulfite in wines were in the range of 1.0-4.1 %. The sampling frequency was65 h-1.

Determination of Sulfite in Wine by Linear Sweep Voltammetry

AbstractA new sensitive electrochemical assay of free sulfite in wine samples at a bare glassy carbon electrode is reported. The method is based on the titration of sulfite with Ellman's reagent using voltammetric detection of the final point. The electrochemical sensing protocol should facilitate rapid field screening of sulfite preservatives.

Determination of sulphite and acetic acid in foods by gas permeation flow injection analysis

Two simple, rapid and sensitive gas-diffusion conductimetric methods were used for the determination of acetic acid and sulphite, separately. For sulphite, the method was based on formation of sulphur dioxide in acid medium (1.5 mol L −1 HCl). The sulphur dioxide formed diffuses through an hydrophobic permeable membrane into an acceptor stream (de-ionised water). The change in the conductivity of the de-ionised water was measured and referred to sulphite content in the samples. The method is applicable in the range of 1.0–50.0 mg L −1 sulphite and the limit of detection is 0.03 μg mL −1. The relative standard deviation for 10 replicate determinations of 10.0 μg mL −1 of sulphite is 0.2%. Sulphite was determined by the method of standard addition. Recovery of sulphite from wine samples ranged from 97.3% to 99.3%. The method was successfully applied to the determination of sulphite in wines and compares well with the standard iodometric method. For acetic acid determination, the method was based on the change of the conductivity of acceptor solution (de-ionised water) when acetic acid from the matrix, diffuses via a permeable membrane into the receptor solution. The increase in conductivity of the de-ionised water was proportional to the acid content. A linear calibration graph in the range of 0.010–0.100 mol L −1 of acetic acid with a relative standard deviation of 0.8% (0.010 mol L −1 acetic acid, N − 10) was obtained. Sample throughputs of 120 h −1 for sulphite and 80 h −1 for acetic acid were achieved. The systems were successfully applied for the assays of sulphite in wines and fruit juices and acetic acid content in vinegar, respectively.

Chemiluminescent determination of sulfite traces based on the induced oxidation of Ni(II)/tetraglycine complex by oxygen in the presence of luminol: mechanistic considerations

The emission produced by sulfite induced autoxidation of Ni(II)/tetraglycine complex in the presence of luminol can be used to determine sulfite in the range of (0.0500–5.00)×10 −6 mol l −1. The limit of detection is 2.8×10 −8 mol l −1 and the relative standard deviation is 4.6% for 1×10 −7 mol l −1 sulfite in five repeated measurements. This method has been successfully used for the determination of sulfite in wine, juices, white sugar and rainwater. The sulfite was extracted from the sample by using one gas-diffusion unit. Results for various samples of wine and juices were compared with those obtained by using a recommended procedure (correlation coefficient=0.9998, n=10), and recovery range for white sugar was between 99 and 104%. The mechanism involves a chain reaction with Ni(II) and radicals formations, which can then oxidize luminol.

Determination of sulphite in wine by coulometric titration

A method for the determination of both free and bound S(IV) in white wine samples by coulometric titration with electrogenerated iodine is described, the S(IV) speciation being performed by extracting SO2 from samples acidified with hydrochloric acid. Titrations of samples treated with NaOH led to the total S(IV) concentration, the results being in agreement with the ones obtained by the distillation procedure as well as by using the classical Monier-Williams method. An average recovery of 97% was obtained for samples spiked with S(IV) in the range 0.4–1.2 mM, which demonstrated the validity of the proposed procedure. The repeatability was 1.3% and the limit of detection was estimated as 0.01 mM. Results from direct titrations of wine added to the electrochemical cell are reported, which give indications of the stability of adducts towards the reaction with iodine.

Determination of sulphite in wine by coulometric titration

Determination of sulphite in wine by coulometric titration

Flow injection determination of sulfite in wines and fruit juices by using a bulk acoustic wave impedance sensor coupled to a membrane separation technique

A flow injection analysis (FIA) method was developed for the rapid determination of sulfite in wines and fruit juices. The method is based on an on-line membrane separation of the SO2 released from a stream of 0.5 M H2SO4 into a stream of 0.01 M H2O2–0.15 mM H2SO4. The conductance increase due to the oxidation of SO2 to H2SO4 is monitored by a bulk acoustic wave impedance sensor and the signal is proportional to the concentration of sulfite present in the original sample. At a throughput of 78 samples h–1, the method exhibited a linear frequency response up to 1.0 mM sulfite with a detection limit of 5.0 µM, and the relative standard deviation of the peak height (n = 6) ranged from 0.57 to 1.23%. Results obtained by the proposed method agreed well with those obtained by conventional iodimetry. The effects of several factors, including those affecting the detector performance and gas transfer process, on the performance of the proposed FIA system were also examined.

Determination of sulphite in wines by gas-diffusion flow injection analysis utilizing spectrophotometric pH-detection

A photometric flow injection analysis (FIA) method, using a gas-diffusion cell, has been developed for the determination of sulphite in wines. The method is based on the change of the absorbance of an indicator solution when sulphur dioxide, liberated from the matrix, diffuses via a permeable membrane into the indicator solution and locally shifts the pH. As indicator, bromocresol green was used. The method is applicable in the range of 1–20mg/l sulphite and the lower limits of detection is 0.1 mg/l. The reproducibility of the analysis for wines are in the range of 0.7–1.5%. Addition of 10% (v/v) ethanol to all solutions and extensively flushing off these solutions with nitrogen before use is crucial to obtain reliable results. The flushing with nitrogen may be considered as a disadvantage of the present method. The method is applicable to red, white and rosé wines. Carbon dioxide interferes the measurement and therefore the method cannot be used for sparkling wines and beers. The results obtained with the FIA method agrees well with the iodometric titration method using biamperometric detection.

Flow-injection analysis with chemiluminescent detection of sulphite using Na 2CO 3NaHCO 3-Cu 2+ system

A simple flow-injection system with chemiluminescent detection for selective determination of sulphite is described. The light accompanying the reaction between sodium carbonate and copper(II) mixture solution with sulphite is detected. The concentration of sulphite is proportional to the chemiluminescence intensity in the range of 1.0 × 10 −6–5 × 10 −4 mol l −1. The limit of detection is 5 × 10 −7 mol l −1 and the relative standard deviation is 4.6% for the 5 × 10 −6 mol l −1 sulphite solution in nine repeated measurements. This method has been successfully applied to the determination of sulphite in wines. The possible reaction mechanism is also discussed.

A Microbial Sensor for Determination of Sulfite in Wines

Abstract The method developed for determining sulfite in wines uses a microbial sensor that consists of sulfur-oxidizing autotrophic bacteria and an oxygen electrode (SO2 meter; SOM), which selectively determines free sulfite in an acidified wine sample. Total sulfite is determined after alkaline extraction; ferrous sulfate is added to the extractant to prevent oxidation. The SOM data showed a coefficient of a variation of 1 % or less (n = 5). The total sulfites in wine determined by SOM were compared with those determined by the Monier–Williams method. Excellent agreement was achieved, as indicated by the regression line for the data: Y = 1.01 X − 1.39 (r = 0.993). With SOM, sulfite can be determined rapidly and accurately with excellent repeatability.

Determination of sulphite in wine by flow injection analysis with indirect electrochemical detection

A flow-injection method has been developed for the determination of total sulphite in wine samples. After hydrolysis of bound sulphite, sulphur dioxide is separated from the matrix by means of an in-line gas diffusion module. For detection indirect amperometry is used, with iodine as oxidizing reagent. The iodine can be generated in-line by merging and mixing iodate and iodide solutions, or alternatively, electrochemically from iodide. With the latter method the best results were obtained. The reproducibility of the peak heights is better than 2%. The linear range of the method can be regulated by adaptation of the current applied to generate the iodine reagent. Due to the low detection limits obtained (0.05 mg L−1), wine samples can be strongly diluted before injection, which makes the sample pretreatment fast and simple. Good agreement has been found with the results obtained for the total sulphite concentration in different wine samples by titration.

Development of a flow injection analysis mediated biosensor for sulfite

Among several mediators tested including N,N,N′,N′-tetramethyl-1,4-phenylenediamine, 2,3,5,6-tetramethyl-1,4-phenylenediamine, tris(2,2′-bipyridyl)ruthenium(II) chloride hexahydrate and 2,6-dichlorophenolindophenol, an organic conducting salt of tetrathiafulvalene (TTF) and tetracyanoquinodimethane (TCNQ) was selected to form a mediated biosensor for sulfite in view of its superior mediating capability to sulfite oxidase. The conducting TCNQ/TTF organic salt and sulfite oxidase were sequentially deposited onto the sensing area of a vitreous carbon electrode which was then covered by a dialysis membrane (MW cut-off 6000–8000). The mediated TCNQ/TTF working electrode was used in connection with flow injection analysis for the determination of sulfite. The linear range of the system was 0 to 5 mM with a detection limit of 5 μM. The electrode achieved 90% of maximum response in 20 s, but required 10 min to return to baseline. The system was tested for 55 repeated analyses during 26 h of continuous operation with no loss of activity. Electrodes bearing both the conducting salt and sulfite oxidase stored in 3 M ammonium sulfate and at 4°C retained 100% of their original activity after 2 months. The biosensor system was applicable for the determination of sulfite in wine, beer and dried fruit samples and the data obtained agreed very well with the pararosaniline reference method.