CN104297304B - AFc/carbon powder/PVB modified electrode preparation and method for determining free state sulfite and amount by electrode - Google Patents
AFc/carbon powder/PVB modified electrode preparation and method for determining free state sulfite and amount by electrode Download PDFInfo
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- CN104297304B CN104297304B CN201410421214.6A CN201410421214A CN104297304B CN 104297304 B CN104297304 B CN 104297304B CN 201410421214 A CN201410421214 A CN 201410421214A CN 104297304 B CN104297304 B CN 104297304B
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Abstract
The invention discloses an AFc/carbon powder/PVB modified electrode, which comprises a glassy carbon electrode and a modification layer fixed on the surface of the glassy carbon electrode; and the modification layer comprises a polyvinyl butyral membrane containing powdered carbon and acetylferrocene absorbed on the surface of the polyvinyl butyral membrane. The invention also discloses a method of the AFc/carbon powder/PVB modified electrode, which comprises the following steps: dispersing acetylferrocene, powdered carbon and polyvinyl butyral resin in absolute ethyl alcohol to prepare a mixed liquor containing AFc/carbon powder/PVB modified substrate, then polishing the glassy carbon electrode, adding the mixed liquor containing AFc/carbon powder/PVB modified substrate drop by drop on the surface of the pretreated glassy carbon electrode, and then naturally drying to obtain the AFc/carbon powder/PVB modified electrode. The invention also discloses a method for detecting sulfite by the AFc/carbon powder/PVB modified electrode, and comprises an application for determining free state sulfite and amount. The method has the advantages of strong anti-interference capability, good stability and high sensitivity.
Description
Technical field
The present invention relates to electrochemical field, more particularly to a kind of AFc/ carbon dusts/PVB modified electrodes and the AFc/ carbon dusts/PVB
The preparation method of modified electrode, and free state sulphite and its total amount are determined using the AFc/ carbon dusts/PVB modified electrodes
Using.
Background technology
The sulfur dioxide that sulfurous acid and its esters and sulfur burning are generated, because there is bleaching, anti-oxidant, anti-corrosion etc. to make for it
With often by as food additives, using quite varied in food processing, but being excessively used danger can be caused to human health
Evil, FAO/WHO specifies the SO that human body is allowed daily2Take the photograph people amount for 0.35-1.50mg/kg (with SO2Meter).Sulfur dioxide is a kind of
The gas of colourless, irritant smell, in daily life Jing food takes in sulphur, sodium sulfite, sodium pyrosulfite etc. to people
The matter of substratess containing sulfur dioxide.Sulfur dioxide is exceeded to produce toxicity, and its toxicity is mainly shown as：Acute sulfur dioxide poisoning can draw
Attract attention, the irritation such as nose, laryngospasm, laryngeal edema, bronchial spasm are produced when serious, a large amount of suctions can cause edema with the lung involved
Swollen, asphyxia, stupor are even dead.The major toxicity for being orally ingested sulfur dioxide shows as gastrointestinal reaction, such as Nausea and vomiting.
Additionally, the exceeded absorption for affecting human body to calcium of sulfur dioxide, and promote the loss of body calcium.Therefore, China is in GB2760
The clear stipulaties limitation of sulphite in foods (is calculated) with the residual quantity of sulfur dioxide, and forbids adding in some food
Plus, but ordering about due to interests, many retailers excessive addition class containing sulfur dioxide bleaching agent in food, to maintain the fresh of food
It is gorgeous, prevent the corruption of food.Therefore, the detection method of sulphite is studied, it is significant to ensureing food security.
At present, it is domestic generally using the sulphite of tetrachloro mercury sodium-pararosaniline hydrochloridc Food
Content, the method reagent dosage is big, and cumbersome, time-consuming, chromogenic reaction temperature influence and make the precision of measure poor, no
The quick inspection of batch samples, and mercury bichloride hypertoxic used in continuous mode can be met, easily to laboratory inner and outer ring
Cause mercury pollution in border.In the past few decades, many analysis methods are applied on detection sulphite, such as spectrophotometric
Method, chemiluminescence, red, orange, green, blue, yellow (ROGBY) and enzyme process etc..All there are shortcomings in these methods, such as analysis time length, high cost,
It is cumbersome etc..These methods generally require and pre-treatment are carried out to sample, cumbersome time-consuming, need corollary equipment more, difficult
To realize live emergency monitoring and on-line analysis.
Electrochemical method is because with easy to operate, efficiently advantage, it has been applied to the detection of many kinds of substance, existing
Have been reported that in document and detect sulphite using glass-carbon electrode, attracted much to grind using electrochemical method detection sulphite
The extensive concern of the person of studying carefully, and make some progress, but the sensitivity of bare glassy carbon electrode detection sulphite can not reach
The requirement of detection.
Therefore, need a kind of quick and convenient and high selectivity of foundation, highly sensitive electrochemical methods badly to determine sulfurous
Hydrochlorate, while also needing to prepare corresponding highly sensitive electrode.This is in food safety monitoring, environmental monitoring, chemical engineering industry life
The fields such as product, online quality monitoring are significant.
The content of the invention
The invention provides a kind of AFc/ carbon dusts/PVB modified electrodes, required material price is cheap, and electrode is easily updated,
Favorable reproducibility, it is nontoxic, it is free from environmental pollution.
The technical scheme of solve problem of the present invention is：A kind of AFc/ carbon dusts/PVB modified electrodes, including glass-carbon electrode and solid
It is scheduled on the decorative layer of glassy carbon electrode surface；The decorative layer includes the polyvinyl butyral film containing carbon dust, and absorption exists
The acetylferrocene on the polyvinyl butyral film surface.
Acetylferrocene (english abbreviation is AFc) can reach good catalysis in sulphite electrocatalytic oxidation and make
With.Polyvinyl butyral resin (english abbreviation is PVB) is the macromolecular material with fixation, not only with good fixation
Effect, stable performance in aqueous, in the range of certain PH, the specific electrically charged state of performance can be formed to specific
The absorption selection index system of material, while the skew of current potential can be affected.
Polyvinyl butyral resin hardly possesses electric conductivity, and polyvinyl butyral film is made after carbon dust by adding wherein
Possess electroactive；And carbon dust has very strong suction-operated, acetylferrocene can be adsorbed onto into polyvinyl butyral film table
Face, increases the effective area of AFc/ carbon dusts/PVB modified electrodes, so that AFc/ carbon dusts/PVB modified electrodes have preferably urging
Change is acted on.
The glass-carbon electrode is made up of the dusty material with high-specific surface area, because its high-specific surface area and minimum grain
Degree, not only with electrical conductive activities, also has catalytic action to specific reaction in certain circumstances.
Preferably, unit area content of the acetylferrocene on glass-carbon electrode is more than 0.0.014 μ g/mm2；Institute
Unit area content of the carbon dust on glass-carbon electrode is stated more than 0.0.28 μ g/mm2。
The content is surface area of the total content by acetylferrocene or carbon on glass-carbon electrode divided by glass-carbon electrode.
The glass-carbon electrode of such as a diameter of 3mm, the content of carbon dust is 2 μ g, then unit area content is 0.28 μ g/mm2。
Used as further preferred, unit area content of the acetylferrocene on glass-carbon electrode is 0.13～0.17 μ
g/mm2, unit area content of the carbon dust on glass-carbon electrode is 4.95～8.49 μ g/mm2。
Unit area content of the acetylferrocene on glass-carbon electrode is 0.046 μ g/mm2When, oxidation peak current is close to most
Big value, reaches 0.061 μ g/mm2When tend to be steady, therefore addition increase will not also increase oxidation peak current；The carbon dust exists
Unit area content on glass-carbon electrode is 1.78 μ g/mm2When, the close maximum of oxidation peak current reaches 6 μ g/mm2When tend to
Steadily, therefore addition increase will not also increase oxidation peak current.
Present invention also offers the preparation method of the AFc/ carbon dusts/PVB modified electrodes, comprises the following steps：
(1) preparation of AFc/ carbon dusts/PVB trim mixed liquors：Acetylferrocene, carbon dust and polyvinyl butyral resin
It is added to after being well mixed in absolute ethyl alcohol, it is ultrasonically treated to make carbon dust be uniformly dispersed in absolute ethyl alcohol after stirring
Obtain AFc/ carbon dusts/PVB trim mixed liquors, set aside for use；
(2) pretreatment of glass-carbon electrode：Glass-carbon electrode polishing is polishing to into minute surface, then successively respectively with 1:1 nitric acid is molten
The cleaning of liquid, absolute ethyl alcohol and distilled water sonic oscillation；Finally in 0.5mol/L sulfuric acid solutions, using above-mentioned cleaned glass carbon
Electrode is circulated voltammetric scan in -0.2V～1.2V potential ranges, and sweep speed is 50mV/s, cyclic activation 10 weeks；
(3) preparation of AFc/ carbon dusts/PVB modified electrodes：Trim mixing drop-coated is being located in advance obtained in removing step (1)
The glassy carbon electrode surface managed, obtains AFc/ carbon dusts/PVB modified electrodes.
In order to preferably be processed glass-carbon electrode, it is preferable that on abrasive paper for metallograph of the polishing grinding using moistening
Polishing, then with 0.3 μm of polishing powder suspended emulsion polishing of particle diameter.The specification of the abrasive paper for metallograph be 3000#, the polishing powder into
This is α-Al2O3。
In food, sulphite exists with free state, three kinds of forms of Reversible binding state and Irreversible binding state.It is right at present
The consumption of sulphite is limited includes free state and Reversible binding state two parts, because the sulphite of Irreversible binding is in physiology
Typically do not dissociate under environment, health will not be worked the mischief.
The sulphite of free state with acid-base value condition difference, can be in HSO3 -、SO3 2-And SO2Convert between three kinds of forms.
Because modified electrode detects the process that response current is that inferior sulfate radical is oxidized to sulfate radical, it can be deduced that pH<6
When, substantially without response current, show now without SO3 2-Exist, the SO when the scope of pH value is 6～83 2-And HSO3 -It is common to exist,
Work as pH>When 8, HSO3 -It is fully converted to SO3 2-, now solution is mainly with SO3 2-Form is present.
Work as pH>When 11, the sulphite of Reversible binding state is discharged.
As pH=8.4, free state inferior sulfate radical is predominantly detected, total amount can be detected as pH=11.0.Described is total
Amount refers to the total amount of the sulphite of free state and Reversible binding state.
Preferably, the mass ratio of the acetylferrocene, carbon dust and polyvinyl butyral resin is 0.0033～0.04:
0.67～1.25:1.
Present invention also offers the method for detecting sulphite using the AFc/ carbon dusts/PVB modified electrodes：
Electrical testing solution is made into using the test solution containing sulphite and as the sodium chloride solution mixing of supporting electrolyte,
Adjust pH value and be more than 8.4, in the potential window of 0～800mV voltammetric scan is circulated, sweep speed is 50mV/s, record knot
Really, by calculating the content for determining sulphite, what is detected when wherein pH value is 8.4～11 is the sulphite of free state,
What is detected when pH value is more than 11 is sulphite total amount.
When the concentration of sulphite is in the range of 0.03～4mmol/L, the linear equation of the concentration of electric current and sulphite
For Iap=2.899+6.935 × 103C, coefficient correlation is 0.9994；Wherein IapFor electric current, unit is μ A, and c is sulphite
Concentration, unit is mol/L.1.5 × 10 are limited to using the detection of AFc/ carbon dusts/PVB modified electrodes detection sulphite-5mol/L。
Concentration of the selection and supporting electrolyte of supporting electrolyte in electrical testing solution can all affect the sensitivity tested,
Preferably, the concentration of the electrical testing Chlorine in Solution sodium is 0.2mol/L.
Response current strengthens as the concentration of sulphite increases, wherein all electro-chemical tests enter at room temperature
OK.
Can meet actual detection using the method for the AFc/ carbon dusts/PVB modified electrodes detection sulphite of the present invention will
Ask, and detect that current potential is relatively low, it is easier to eliminate interference, selective good, the sensitivity height in sulphite detection.
Description of the drawings
Fig. 1 is the cyclic voltammetry curve of AFc/ carbon dusts/PVB modified electrodes that embodiment 1 is prepared.
Fig. 2 is the cyclic voltammetry curve of AFc/ carbon dusts/PVB modified electrodes that embodiment 2 is prepared.
Fig. 3 is the cyclic voltammetry curve of AFc/ carbon dusts/PVB modified electrodes that embodiment 3 is prepared.
Fig. 4 is the cyclic voltammetry curve of AFc/ carbon dusts/PVB modified electrodes that embodiment 4 is prepared.
Fig. 5 is the cyclic voltammetry curve that application examples 1 detects sulphite.
Fig. 6 is the cyclic voltammetry curve that application examples 2 detects sulphite.
Fig. 7 is the cyclic voltammetry curve that application examples 3 detects sulphite.
Fig. 8 is the cyclic voltammetry curve that application examples 4 detects sulphite.
Fig. 9 is the cyclic voltammetry curve comparison diagram of the AFc/ carbon dusts/PVB modified electrodes with exposed glass-carbon electrode of the present invention.
Figure 10 is the glass-carbon electrode of carbon dust/AFc/nafion modifications in 0.2mol/L NaCl (a) and 2mmolL-1Sulfurous
In hydrochlorate (b)；The glass-carbon electrode of AFc/nafion modifications is in 0.2mol/L NaCl (c) and 2mmolL-1Sulphite (d),
The cyclic voltammogram tested under the sweep speed of 50mV/s.
Figure 11 be exposed glass-carbon electrode (a), PVB modify glass-carbon electrode (b), AFc/PVB modification glass-carbon electrode (c),
The glass-carbon electrode (d) and AFc/ carbon dusts/PVB modified electrodes (e) of carbon dust/PVB modifications is at 2mmol/L sulphite (A)
With the circulation swept under second speed of 50mV/s in (0.2mol/L NaCl are used as supporting electrolyte) and 0.2mol/L NaCl (B)
Volt-ampere curve；Insertion portion A is the subduplicate linear relationship of oxidation peak current and sweep speed.
Figure 12 is that under different pH values, the AFc/ carbon dusts/PVB modified electrodes of the present invention are respectively in 2mmol L-1Sulfurous acid
Electrochemical response curve in sodium (A), 2mmol/L sodium pyrosulfites (C) and 2mmol/L sodium hydroxymethane sulfonates (B).
Figure 13 is the AFc/ carbon dusts/PVB modified electrodes using the present invention, in the Asia that concentration range is 0.03 to 4mmol/L
In sulfate, 0.2molL-1NaCl (pH 8.4) as supporting electrolyte, using the sweep speed of 50mV/s, the circulation for measuring
Voltammogram；Insertion portion is in response to the calibration curve of electric current and sulfite concentration.
Figure 14 is the impact of trim carbon dust (A) consumption and AFc (B) consumptions to oxidation peak current.
Specific embodiment
With reference to specific embodiment, the invention will be further described.
Embodiment 1
(1) preparation of AFc/ carbon dusts/PVB trim mixed liquors:
Polyvinyl butyral resin (PVB) mixing for weighing 0.4mg acetylferrocenes, 11.67mg carbon dusts and 10mg is equal
After even, in being added to the absolute ethyl alcohol of 1mL, after stirring, ultrasonically treated 1～2min makes carbon dust in absolute ethyl alcohol
It is uniformly dispersed and obtains AFc/ carbon dusts/PVB trim mixed liquors, stands 5min stand-by；
(2) pretreatment of glass-carbon electrode：
Glass-carbon electrode is polished on the abrasive paper for metallograph (3000#) of moistening, then with polishing powder that particle diameter is 0.3 μm (α-
Al2O3) suspended emulsion is polishing to minute surface, then successively with 1:1 salpeter solution, absolute ethyl alcohol and distilled water are super to glass-carbon electrode respectively
Sound cleans 4～5min, in 0.5mol/L sulfuric acid solutions, by above-mentioned cleaned glass-carbon electrode in -0.2V～1.2V current potential models
It is circulated voltammetric scan in enclosing, sweep speed is 50mV/s, cyclic activation 10 weeks.
(3) preparation of AFc/ carbon dusts/PVB modified electrodes：
AFc/ carbon dusts obtained in 3.0 μ L steps (1)/PVB trims mixing drop-coated is pipetted in the glass carbon electricity for having pre-processed
Pole surface, spontaneously dries at room temperature 2～3h, that is, make AFc/ carbon dusts/PVB modified electrodes.
Embodiment 2
(1) preparation of AFc/ carbon dusts/PVB trim mixed liquors:
The polyvinyl butyral resin (PVB) for weighing 0.4mg acetylferrocenes, 0.67mg carbon dusts and 10mg is well mixed
Afterwards, it is added in the absolute ethyl alcohol of 1mL, after stirring, ultrasonically treated 1～2min makes carbon dust divide in absolute ethyl alcohol
Dissipate and uniformly obtain AFc/ carbon dusts/PVB trim mixed liquors, stand 5min stand-by；
(2) pretreatment of glass-carbon electrode：
Glass-carbon electrode is polished on the abrasive paper for metallograph (3000#) of moistening, then with polishing powder that particle diameter is 0.3 μm (α-
Al2O3) suspended emulsion is polishing to minute surface, then successively with 1:1 salpeter solution, absolute ethyl alcohol and distilled water are super to glass-carbon electrode respectively
Sound cleans 4～5min, in 0.5mol/L sulfuric acid solutions, by above-mentioned cleaned glass-carbon electrode in -0.2V～1.2V current potential models
It is circulated voltammetric scan in enclosing, sweep speed is 50mV/s, cyclic activation 10 weeks.
(3) preparation of AFc/ carbon dusts/PVB modified electrodes：
AFc/ carbon dusts obtained in 3.0 μ L steps (1)/PVB trims mixing drop-coated is pipetted in the glass carbon electricity for having pre-processed
Pole surface, spontaneously dries at room temperature 2～3h, that is, make AFc/ carbon dusts/PVB modified electrodes.
Embodiment 3
(1) preparation of AFc/ carbon dusts/PVB trim mixed liquors:
Polyvinyl butyral resin (PVB) mixing for weighing 0.033mg acetylferrocenes, 12.5mg carbon dusts and 10mg is equal
After even, in being added to the absolute ethyl alcohol of 1mL, after stirring, ultrasonically treated 1～2min makes carbon dust in absolute ethyl alcohol
It is uniformly dispersed and obtains AFc/ carbon dusts/PVB trim mixed liquors, stands 5min stand-by；
(2) pretreatment of glass-carbon electrode：
Glass-carbon electrode is polished on the abrasive paper for metallograph (3000#) of moistening, then with polishing powder that particle diameter is 0.3 μm (α-
Al2O3) suspended emulsion is polishing to minute surface, then successively with 1:1 salpeter solution, absolute ethyl alcohol and distilled water are super to glass-carbon electrode respectively
Sound cleans 4～5min, in 0.5mol/L sulfuric acid solutions, by above-mentioned cleaned glass-carbon electrode in -0.2V～1.2V current potential models
It is circulated voltammetric scan in enclosing, sweep speed is 50mV/s, cyclic activation 10 weeks.
(3) preparation of AFc/ carbon dusts/PVB modified electrodes：
AFc/ carbon dusts obtained in 3.0 μ L steps (1)/PVB trims mixing drop-coated is pipetted in the glass carbon electricity for having pre-processed
Pole surface, spontaneously dries at room temperature 2～3h, that is, make AFc/ carbon dusts/PVB modified electrodes.
Embodiment 4
(1) preparation of AFc/ carbon dusts/PVB trim mixed liquors:
The polyvinyl butyral resin (PVB) for weighing 0.4mg acetylferrocenes, 12.5mg carbon dusts and 10mg is well mixed
Afterwards, it is added in the absolute ethyl alcohol of 1mL, after stirring, ultrasonically treated 1～2min makes carbon dust divide in absolute ethyl alcohol
Dissipate and uniformly obtain AFc/ carbon dusts/PVB trim mixed liquors, stand 5min stand-by；
(2) pretreatment of glass-carbon electrode：
Glass-carbon electrode is polished on the abrasive paper for metallograph (3000#) of moistening, then with polishing powder that particle diameter is 0.3 μm (α-
Al2O3) suspended emulsion is polishing to minute surface, then successively with 1:1 salpeter solution, absolute ethyl alcohol and distilled water are super to glass-carbon electrode respectively
Sound cleans 4～5min, in 0.5mol/L sulfuric acid solutions, by above-mentioned cleaned glass-carbon electrode in -0.2V～1.2V current potential models
It is circulated voltammetric scan in enclosing, sweep speed is 50mV/s, cyclic activation 10 weeks.
(3) preparation of AFc/ carbon dusts/PVB modified electrodes：
AFc/ carbon dusts obtained in 3.0 μ L steps (1)/PVB trims mixing drop-coated is pipetted in the glass carbon electricity for having pre-processed
Pole surface, spontaneously dries at room temperature 2～3h, that is, make AFc/ carbon dusts/PVB modified electrodes.
It is circulated volt-ampere test, the curve for obtaining with the AFc/ carbon dusts/PVB modified electrodes for obtaining for implementing 1～4 respectively
As shown in figures 1-4.
Application examples 1
The method for determining sulphite using the AFc/ carbon dusts/PVB modified electrodes of the present invention：Pipette a certain amount of test solution
Electrical testing solution is made in 10mL volumetric flasks with 1mol/L sodium chloride solutions 2mL, in moving into electrolysis cup, it is 8.4 to adjust pH value；With
AFc/ carbon dusts/PVB modified electrodes that embodiment 1 is obtained are circulated voltammetric scan, scanning speed in the potential window of 0～800mV
Rate is 50mV/s, records result, and corresponding curve is as shown in Figure 5.
Application examples 2
The method for determining sulphite using the AFc/ carbon dusts/PVB modified electrodes of the present invention：Pipette a certain amount of test solution
Electrical testing solution is made in 10mL volumetric flasks with 1mol/L sodium chloride solutions 2mL, in moving into electrolysis cup, it is 11 to adjust pH value；With
AFc/ carbon dusts/PVB modified electrodes that embodiment 1 is obtained are circulated voltammetric scan, scanning speed in the potential window of 0～800mV
Rate is 50mV/s, records result, and corresponding curve is as shown in Figure 6.
Application examples 3
The method for determining sulphite using the AFc/ carbon dusts/PVB modified electrodes of the present invention：Pipette a certain amount of standard sub-
Sulfate liquor and 1mol/L sodium chloride solutions 2mL are made into electrical testing solution in 10mL volumetric flasks, control sulfite concentration and are
0.03mmol/L, in moving into electrolysis cup, it is 8.4 to adjust pH value；AFc/ carbon dusts/PVB the modified electrodes obtained with embodiment 1 are 0
The potential window of～800mV is circulated voltammetric scan, and sweep speed is 50mV/s, records result, corresponding curve such as Fig. 7 institutes
Show.
Application examples 4
The method for determining sulphite using the AFc/ carbon dusts/PVB modified electrodes of the present invention：Pipette a certain amount of standard sub-
Sulfate liquor and 1mol/L sodium chloride solutions 2mL are made into electrical testing solution in 10mL volumetric flasks, control sulfite concentration and are
4mmol/L, in moving into electrolysis cup, it is 8.4 to adjust pH value；AFc/ carbon dusts/PVB the modified electrodes obtained with embodiment 1 0～
The potential window of 800mV is circulated voltammetric scan, and sweep speed is 50mV/s, records result, corresponding curve such as Fig. 8 institutes
Show.
Test experiments and analysis
The concentration of a diameter of 3mm of glass-carbon electrode adopted in below testing, sodium chloride and sulphite is referred in electrical measurement
Concentration in examination solution.
In order to the AFc/ carbon dusts/PVB modified electrodes for illustrating the present invention have preferably sensitivity, by the AFc/ carbon of the present invention
Powder/PVB modified electrodes carry out contrast test with exposed glass-carbon electrode, and corresponding cyclic voltammetry curve is as shown in figure 9, can from Fig. 9
To find out that AFc/ carbon dusts/PVB modified electrodes have the redox peaks for becoming apparent from compared with bare electrode.
Because perfluorinated sulfonic resin (english abbreviation is Nafion) has excellent film forming, dissolving dispersibility, stability
And ion-exchange capacity, it is widely used in chemically modified electrode, therefore the present invention substitutes polyvinyl alcohol contracting fourth with Nafion
Aldehyde is made the glass-carbon electrode of carbon dust/AFc/nafion modifications and is tested, and corresponding cyclic voltammetry curve is as shown in Figure 10, from
It can be seen that using the glass-carbon electrode of carbon dust/AFc/nafion modifications in sulfite solution change in concentration, responding in Figure 10
Electric current has almost no change, and illustrates using the sensitive of the electrode detection sulphite of conventional trim perfluorinated sulfonic resin modification
Property it is very poor, even if addition carbon dust modification, also simply have slight change.Illustrate polyvinyl butyral resin not only as acetyl two
The carrier of luxuriant iron and carbon dust, polyvinyl butyral resin can also affect the sensitivity of final modified electrode.
In order to test the effect of acetylferrocene, carbon and PVB played in modified electrode respectively, exposed glass carbon electricity is prepared for
Pole, the glass-carbon electrode of PVB modifications, the glass-carbon electrode of PVB/AFc modifications, the glass-carbon electrode of carbon dust/PVB modifications and AFc/ carbon dusts/
PVB modified electrodes, are circulated volt-ampere test in the test solution of the sodium chloride as supporting electrolyte of 0.2mol/L, such as scheme
Shown in 11, wherein only carbon dust/AFc/PVB modified electrodes have complete redox peaks when sodium chloride is as supporting electrolyte
Electric current, this is also the redox peaks of AFc, and this AFc/ carbon dusts/PVB modification formulas can give full play to the effect of AFc.
The sulphite of 2mmol/L is with the addition of in test solution in Figure 11 corresponding to part A curve, part B is used as sky
White contrast.The curve of contrast part A and part B can show that AFc/ carbon dusts/PVB modified electrodes have substantially in sulfurous acid solution
Catalytic effect, it can be seen that have obvious sulphite catalysis oxidation current peak, AFc/ carbon dusts/PVB modified electrodes can be used
In catalytic determination sulphite, while this peak current has good linear relationship with the square root of sweep speed.
Sulphite in food is typical from the sodium sulfite and sodium pyrosulfite being added in food, sulphite
To realize anti-oxidant, BPH resistant rice variety, preservation.Sulphite in food can be with free state, Reversible binding state, Irreversible binding
State is present.Wherein Irreversible binding state sulfurous acid is sub- is referred to as not as detection target, free state and Reversible binding state cigarette sulfate
Total amount.
For impact of the simulation test pH value to the AFc/ carbon dusts/PVB modified electrodes of the present invention in detection sulphite,
Using sodium hydroxymethane sulfonate (english abbreviation is as HMS) as the model compound of Reversible binding state, sodium sulfite and sodium pyrosulfite
Detection test is carried out as the form for being free state sulphite, corresponding test curve is as shown in figure 12, wherein sodium sulfite
Corresponding is part A curve, and it is C portion curve that sodium pyrosulfite is corresponding, and it is part B curve that HMS is corresponding.
As can be seen from Figure 12 in the range of 8.4～11, part A curve and C portion curve have significantly response to pH value
Curent change, and part B curve is not changed in.Part B curve just has obvious curent change when pH value is more than 11.Sodium sulfite
Exist in inferior sulfate radical form when pH value is 8.4 with sodium pyrosulfite, can be arrived by electrode detection, and HMS is more than in pH value
Just decompose when 11 and produce sulfite ion and be detected.Illustrate that pH value detects in the range of 8.4～11 is free sulfurous
Hydrochlorate, and pH value is when being more than 11, HMS resolves into inferior sulfate radical, and the sodium sulfite that adds and sodium pyrosulfite are still with sulfurous acid
Root form is present, it is believed that what is now extracted is sulphite total amount.Therefore pH value can be adjusted carrys out selective enumeration method not
With the sulphite of form.
In order to prove stability and sensitivity of the AFc/ carbon dusts/PVB modified electrodes of the present invention when sulphite is detected
And detection sulphite lower limit, detected with the sulphite of multigroup variable concentrations respectively, concentration range from
4mmol/L is gradually reduced, and as shown in figure 13, as sulfite concentration is reduced, corresponding response current reduces corresponding curve,
The redox peaks of sulphite also become flat, can be seen that the concentration of sulphite in 0.03～4mmol/ from wherein illustration
During L, response current is clear and definite with the concentration linear relationship of sulphite, and response current is with the linear equation of the concentration of sulphite
Iap=2.899+6.935 × 103C, coefficient correlation is 0.999；Wherein IapFor electric current, unit is μ A, and c is dense for sulphite
Degree, unit is mol/L.Illustrate that AFc/ carbon dusts/PVB modified electrodes are that the sulphite of 0.03～4mmol/L has to concentration range
Very stable Detection results, AFc/ carbon dusts/PVB modified electrodes are well suited for for detecting sulphite, AFc/ carbon dusts/PVB modifications
Electrode can be with the concentration limit of detecting the contet of sulphate as 15 μm of ol/L.
In order to further probe into the impact of the addition AFc/ carbon dusts/PVB modified electrodes of acetylferrocene and carbon dust, respectively
Tested with the AFc/ carbon dusts/PVB modified electrodes containing not same amount acetylferrocene and carbon dust, corresponding curve such as Figure 14 institutes
Show, as can be seen from Figure 14 the adding proportion of acetylferrocene and carbon dust has a positive correlation with the size of peak current,
Gradually increase as the addition of acetylferrocene or carbon dust increases peak current, but reach after a certain amount to peak current
Impact diminishes, and tends towards stability, and acetylferrocene and carbon dust are not The more the better.As can be seen from Figure 14 acetylferrocene is most
Little consumption is 0.1 μ g, and corresponding unit area content is 0.014 μ g/mm2；The minimum amount of carbon dust be 2 μ g, corresponding unit
Area fraction is 0.28 μ g/mm2；Acetylferrocene preferably total amount scope be 0.9～1.2 μ g, corresponding unit area content
For 0.13～0.17 μ g/mm2；Carbon dust preferably total amount scope be 35～60 μ g, corresponding unit area content be 4.95～
8.49μg/mm2。
Claims (8)
1. a kind of AFc/ carbon dusts/PVB modified electrodes, including glass-carbon electrode and the decorative layer for being fixed on glassy carbon electrode surface；It is described
Decorative layer includes the polyvinyl butyral film containing carbon dust, and absorption in the acetyl on the polyvinyl butyral film surface
Ferrocene.
2. AFc/ carbon dusts/PVB modified electrodes as claimed in claim 1, it is characterised in that：The acetylferrocene is in glass carbon electricity
The unit area content for extremely going up is more than 0.014 μ g/mm2；Unit area content of the carbon dust on glass-carbon electrode is more than 0.28 μ
g/mm2。
3. AFc/ carbon dusts/PVB modified electrodes as claimed in claim 2, it is characterised in that：The acetylferrocene is in glass carbon electricity
The unit area content for extremely going up is 0.13～0.17 μ g/mm2, unit area content of the carbon dust on glass-carbon electrode is 4.95
～8.49 μ g/mm2。
4. a kind of preparation method of AFc/ carbon dusts/PVB modified electrodes as claimed in claim 1：Characterized in that, including following
Step：
(1) preparation of AFc/ carbon dusts/PVB trim mixed liquors：The mixing of acetylferrocene, carbon dust and polyvinyl butyral resin
It is added in absolute ethyl alcohol after uniform, it is ultrasonically treated to make carbon dust be uniformly dispersed in absolute ethyl alcohol to obtain after stirring
Containing AFc/ carbon dusts/PVB trim mixed liquors, set aside for use；
(2) pretreatment of glass-carbon electrode：Glass-carbon electrode polishing is polishing to into minute surface, then successively respectively with 1:1 salpeter solution, nothing
Water-ethanol and distilled water sonic oscillation are cleaned；Finally in 0.5mol/L sulfuric acid solutions, using above-mentioned cleaned glass-carbon electrode
It is circulated voltammetric scan in -0.2V～1.2V potential ranges, sweep speed is 50mV/s, cyclic activation 10 weeks；
(3) preparation of AFc/ carbon dusts/PVB modified electrodes：Trim mixing drop-coated is being pre-processed obtained in removing step (1)
Glassy carbon electrode surface, obtain AFc/ carbon dusts/PVB modified electrodes.
5. preparation method as claimed in claim 4, it is characterised in that：The polishing polishing is using mill on the abrasive paper for metallograph of moistening
Light, then with 0.3 μm of polishing powder suspended emulsion polishing of particle diameter.
6. the method that one kind detects sulphite using AFc/ carbon dusts as claimed in claim 1/PVB modified electrodes, its feature
It is：Electrical testing solution is made into using the test solution containing sulphite and as the sodium chloride solution mixing of supporting electrolyte, is adjusted
Section pH value is more than or equal to 8.4, and in the potential window of 0～800mV voltammetric scan is circulated, and sweep speed is 50mV/s, record
As a result, by calculating the content for determining sulphite, what is detected when wherein pH value is 8.4～11 is the sulfurous acid of free state
Salt, what is detected when pH value is more than 11 is sulphite total amount.
7. the method that AFc/ carbon dusts as claimed in claim 6/PVB modified electrodes detect sulphite, it is characterised in that：Sulfurous
When the concentration of hydrochlorate is in the range of 0.03～4mmol/L, electric current is I with the linear equation of the concentration of sulphiteap=2.899+
6.935×103C, coefficient correlation is 0.9994；Wherein IapFor electric current, unit is μ A, and c is the concentration of sulphite, and unit is
mol/L。
8. the method that AFc/ carbon dusts as claimed in claim 6/PVB modified electrodes detect sulphite, it is characterised in that：It is described
The concentration of electrical testing Chlorine in Solution sodium is 0.2mol/L.
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