CN101893594A - The electrochemical determination method of arsenic and device thereof - Google Patents
The electrochemical determination method of arsenic and device thereof Download PDFInfo
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- CN101893594A CN101893594A CN2010101926606A CN201010192660A CN101893594A CN 101893594 A CN101893594 A CN 101893594A CN 2010101926606 A CN2010101926606 A CN 2010101926606A CN 201010192660 A CN201010192660 A CN 201010192660A CN 101893594 A CN101893594 A CN 101893594A
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Abstract
Provide a kind of by electrochemical method, with easy operation and device, high precision and detect arsenic or arsenic compound in high sensitivity and measure the assay method and the device of its concentration.Comprise following operation: the operation that in above-mentioned sample solution, adds gold; The current potential that makes above-mentioned conductive diamond electrode is to the change of negative potential direction, allows arsenic and the golden electro-deposition electro-deposition operation on above-mentioned conductive diamond electrode surface; And, make the operation of separating out that the arsenic of electro-deposition on the above-mentioned conductive diamond electrode surface parses in said sample solution to the current potential of the above-mentioned conductive diamond electrode of positive potential scanning direction.
Description
Technical field
The present invention relates to by electrochemical method, with easy operation and device, high precision and detect arsenic or arsenic compound in high sensitivity and measure the assay method and the device thereof of its concentration.
Background technology
Arsenic (As) is a kind ofly to enter into human body by potable water and food easily, causes arsenic poisoning behind the savings in human body, and a kind of extremely harmful element that can cause death.
The exploitation arsenic-containing ores is used to produce arsenous acid anhydride on the arsenic minerals mountain, and zinc refiner reduces in taking off the clean liquid operation of cadmium and produces arsine (AsH when reclaiming cadmium
3).Also have, use the discarded object of semiconductor factory's generation arsenical of gallium arsenide (GaAs) and arsenic iridium (IrAs), moreover, in the manufacture process of optical glass and electric glass specific glass such as (Electricity mood ガ ラ ス), the situation of arsenous acid anhydride as clarificant of using arranged also.Therefore, probably contain arsenic in the discharge water of these facilities.In addition, arsenic compound also had the period as wood preservative and termite repellant use.So arsenic infiltrates into underground water, underground water probably can cause above-described arsenic poisoning phenomenon after being taken in by human body as potable water.
Poisonous element as arsenic, water pollution prevent that its content benchmark is below the 0.1ppm (100ppb) in the law regulation discharge water, and in addition, its content benchmark is below the 0.01ppm (10ppb) in the WHO potable water.For this reason, need a kind of easy and detection method that precision is good, can detect the compound concentrations of arsenic and arsenic in discharge water and the potable water.
We know several methods by electrochemical gaging arsenic, and are for example, disclosed in the patent documentation 1～3.Yet, in patent documentation 1 disclosed method, use gold electrode as working electrode, check in gold electrode surfaces by As (III) electro-deposition, but for electro-deposition the higher high price oxidation number As (V) of oxidation-reduction potential and added bigger negative potential, make that the competitive reaction that electrodeposit reaction takes place electrode surface easily is the electrolytic reaction generation hydrogen of water, and be difficult for taking place the electrodeposit reaction of As (V), so make the method check become difficult.
In addition, in patent documentation 2 disclosed methods, use the boron-doped diamond electrode that has injected the Ir ion as working electrode, this electrode also is to measure the concentration of As (III) by the oxidation current of direct detection As (III) → As (V).But it can't measure the concentration of As (V).
Further, in patent documentation 3 disclosed methods, the boron-doped diamond electrode that uses surface gold-plating is as working electrode (to call the BDD-Au electrode in the following text), but its As for low concentration (V) insufficient sensitivity, the As (V) of concentration below 250ppb is difficult to be detected.In addition, every group of interelectrode difference of BDD-Au is big, at aspects such as semaphore and electron lifetime deviation is arranged all.Moreover the BDD-Au electrode is through after using repeatedly, and the gold-plated of surface can dissolve, and causes sensitivity to reduce more, causes the problem of poor reproducibility.
Patent documentation 1: the Jap.P. spy opens 2007-304081
Patent documentation 2: the Jap.P. spy opens 2006-98281
Patent documentation 3: the Jap.P. spy opens 2008-216061
Summary of the invention
Therefore the present invention makes every effort to provide a kind of electrochemical assay method and device thereof, by electrochemical method with easy operation and device, high precision and detect arsenic or arsenic compound in high sensitivity and measure its concentration.
The arsenic electrochemical determination method that promptly the present invention relates to is to use to electrode with by the working electrode that the conductive diamond electrode is constituted and measures the concentration of arsenic in the sample solution, it is characterized in that possessing following operation: the operation that adds gold in above-mentioned sample solution; The current potential that makes above-mentioned conductive diamond electrode is to the change of negative potential direction, arsenic and the golden electro-deposition electro-deposition operation to the above-mentioned conductive diamond electrode surface; And, make the operation of separating out that the arsenic of above-mentioned conductive diamond electrode surface electro-deposition parses in said sample solution to the current potential of the above-mentioned conductive diamond electrode of positive potential scanning direction.
So, gold is joined sample solution, itself and arsenic are present in the sample solution jointly, by making arsenic and the common electro-deposition of gold, thereby can analyze the arsenic of low concentration in high sensitivity on the surface of above-mentioned conductive diamond electrode.This method with in advance golden electro-deposition is compared in the situation of electrode surface, improved as the electrode reaction active site tremendously and had the gold of catalysis and the contact probability of arsenic, thereby promoted the generation of the electrode reaction of arsenic significantly.Therefore, according to the present invention, can make over by the BDD-Au electrode under optimum determining condition, the detection that all is difficult to the following arsenic of 250ppb concentration measured becomes possibility, and has improved sensitivity significantly.
In addition, according to patent documentation 3 disclosed methods, must be in advance with deposition of gold on the surface of boron-doped diamond electrode, and in the present invention, only need that gold is joined sample solution to get final product, operate extremely easy.Moreover, among the present invention owing to gold joined sample solution get final product, when therefore not needing picture use BDD-Au electrode, for obtain electrode in batch between performance homogenising and carry out control highly.
The conductive diamond electrode that uses among the present invention, give in the conductive diamond electrode of diamond thin electric conductivity by mixing 13 families or 15 family's elements, preferably mix the electrode of the central at least a element of boron, nitrogen and phosphorus, special, the boron-doped diamond electrode that mixes boron is optimum.
For carbon electrode, add-during negative potential about 1.0V, the competitive reaction that electrodeposit reaction takes place easily is that the electrolytic reaction of water generates hydrogen, so the electro-deposition of As (V) is difficult takes place, and causes the problem that electrode worsens.But for the boron-doped diamond electrode, even if add-negative potential about 1.0V also is difficult for causing such problem.
In the said sample solution, the Concentrated degree of chloride ion is 1.5～2.5M, and preferred pH value is acid.Herein, the pH value more preferably 0.5～1.5.With this understanding, the electrochemical determination method to arsenic that the present invention relates to can improve the detection sensitivity of arsenic significantly.For example, the concentration of NaCl in the sample solution is added to 2M, the pH value is adjusted into 1.0, and (PBS 0.1M pH5.0) compares, and it is high about 50 times that its sensitivity is wanted with disclosed condition in the patent documentation 3.This can think that owing to working as chloride ion concentration be 1.5～2.5M, pH is 0.5～1.5 o'clock, arsenic ion and gold ion form stable complex compound with chloride ion respectively, the state electro-deposition that disperses with homogeneous between arsenic ion and gold ion is at electrode surface, make contact area between gold and arsenic further extended due to.
In addition, chloride ion concentration is in above-mentioned scope, and the full width at half maximum of electric current crest itself is quite little, can access tangible crest.This is because the complex compound that arsenic ion and gold ion and chloride ion form has produced influence to the electronics translational speed.So also so hardly be subjected to the interference of interfering materials such as other metals.Moreover, if chloride ion concentration is in above-mentioned scope, owing to there is excessive Cl
-Ion, and then can get rid of Br
-Etc. anionic influence.
The addition of above-mentioned gold can be excessive greatly with respect to the arsenic in the sample solution, also can select rightly according to the concentration of arsenic, for example, the concentration of gold in the sample solution can be added to 10～1000ppm.
The electrochemical determination method of the arsenic that the present invention relates to can be implemented by the determinator that for example contains following formation.Also promptly have following feature: a kind of being used for measured the device that has added golden sample solution arsenic concentration with electrochemical means, comprise: groove, in be provided with to electrode and make arsenic and golden electro-deposition at this working electrode that conductive diamond electrode of electrode surface is constituted; The potential change device, it makes the current potential of above-mentioned conductive diamond electrode change to the negative potential direction, provide and make arsenic and golden electro-deposition some position on the surface of above-mentioned conductive diamond electrode, then, the current potential that makes above-mentioned conductive diamond electrode is to the change of positive potential direction, the current potential that provides the arsenic that makes electro-deposition on the above-mentioned conductive diamond electrode surface to parse in sample solution; Pick-up unit, the electric current that its potential change that detects above-mentioned conductive diamond electrode causes changes; Signal conditioning package, detected electric current variation calculates arsenic concentration according to above-mentioned detection device for it.The electrochemical determining device of this arsenic also is a part of the present invention.
The effect of invention
According to the present invention, utilize electrochemical reaction to detect arsenic and when measuring the concentration of arsenic, by in sample solution, adding gold, with easy operation and device thereof, can high precision and high sensitivity, and have good reappearance ground and detect arsenic and measure its concentration.
Description of drawings
The concise and to the point figure of the electrochemical determining device that [Fig. 1] one embodiment of the present of invention relate to.
[Fig. 2] expression uses the boron-doped diamond electrode electro Chemical to measure the resulting result's of As (V) solution chart, and (a) expression voltammogram (b) is represented As (V) concentration and detected current value correlationship figure.
[Fig. 3] expression uses the BDD-Au electrode electro Chemical to measure the resulting result of As (V) solution, and (a) expression voltammogram (b) is represented As (V) concentration and detected current value correlationship figure
The boron-doped diamond electrode is used in [Fig. 4] expression, changes change pH values, the voltammogram of electrochemical gaging As (III) solution gained.
Embodiment
Below, with reference to accompanying drawing a specific embodiment of the present invention is described.
As shown in Figure 1, the electrochemical determining device that relates to of present embodiment 1 uses is electrochemical gaging with batch tank (bacth cell).
The electrochemical determining device 1 that present embodiment relates to possesses boron-doped diamond electrode 2, to electrode 3 and contrast electrode 4, and in be provided with the detection groove 5 of these 3 electrodes, boron-doped diamond electrode 2, electrode 3 is connected with potentiostat 7 with contrast electrode 4, and potentiostat 7 is connected with signal conditioning package 8 again.In addition, detect groove 5 and be provided with the stirrer that stirs sample solution S.
Below each one is described.Boron-doped diamond electrode 2 is originally to be to make it have the electric conductivity gained in the adamas of insulator by boron is sneaked into, the function of performance working electrode in electrochemical determining device 1.Oozing mixes has the boron-doped diamond electrode 2 of high concentration boron to have following advantageous property: have very wide electromotive force window (the equal broad of oxidizing potential and reduction potential), compare with other electrode materials, has lower background current, highly sensitive to different reductant-oxidants, compare with platinum etc. with gold, because its surface is difficult for physisorption takes place, so be not prone to the peak value beyond the oxygen hydrogen.In addition, the chemical durability of boron-doped diamond electrode 2, mechanical endurance, conductivity, corrosion resistance etc. are also excellent.Further, boron-doped diamond electrode 2 is because its hardness, and carries out the cleaning of the physics of chemistry easily, therefore also has the advantage of the state that electrode surface easily keeps clean.
The addition of the boron that mixes in order to make adamas obtain electric conductivity carries out suitable decision in the scope that can give adamas electric conductivity and gets final product, and for example, preferably gives 1 * 10
-2～10
-6The dosage of Ω cm left and right sides electric conductivity.
Though boron-doped diamond self also can be used as electrode without the support of base material, but preferably forms boron-doped diamond film on base material, connect lead as electrode by this film.Above-mentioned base material can be enumerated Si (for example, monocrystalline silicon), Mo, W, Nb, Ti, Fe, Au, Ni, Co, Al
2O
3, SiC, Si
3N
4, ZrO
2, MgO, graphite, single-crystal diamond, cBN, quartz glass etc., especially suitable monocrystalline silicon, Mo, W, Nb, Ti, SiC, the single-crystal diamond of using.
The thickness of boron-doped diamond film is not particularly limited, about preferred 1～100 μ m, more preferably about 5～50 μ m.
For the shape of boron-doped diamond electrode 2, bar-shapedly or plane all can.In addition, electrode surface can like this keep the growing up state of (as-grown) also can carry out hydrogen annealing to it, the physical treatment of the surface configuration of chemical surface treatment such as electrolytic oxidation or planarization of being undertaken by various grindings etc.
Electrode 3 is used to compensate Faradaic current, for example can selects for use, by platinum, carbon, stainless steel, gold, adamas, SnO
2At the electrode that constitutes.
Known common electrode all can be elected to be contrast electrode 4, for example can use silver-silver chloride electrode, mercurous chloride electrode, standard hydrogen electrode, hydrogen-palladium electrode etc.
Detect in the groove 5 and store sample solution S, its constitute this sample solution S can with boron-doped diamond electrode 2, electrode 3 and contrast electrode 4 are connected.For detecting groove 5, its inside can store sample solution S and get final product, and its material is not particularly limited, and preferably prevents the resin prepared materials such as teflon that impurity is separated out as far as possible.
Stirrer 6 is used to stir the sample solution S that detects storage in the groove 5.Stir sample solution S by stirrer 6 and improve arsenic and golden electro-deposition rate for boron-doped diamond electrode 2.Rotating manner for shape, material and the blade of stirrer 6 blades all is not particularly limited, the setting that preferably can fully stir sample solution S and suppress the generation of impurity and micro powder as much as possible and suppress electrode surface generation bubble, for example, the cross stirrer of suitable use.
Next, use electrochemical determining device 1 to describe according to the detection method of stripping voltammetry to arsenic.At first, the carrier solution that only will not contain determination object arsenic is injected into and detects groove 5, makes background current as far as possible little and stable.Then, add HCl in containing the sample solution S of arsenic, make that the content of HCl becomes 0.1M in the solution, the pH value is 1, adds NaCl, makes that the concentration of NaCl is 2M.Moreover, add AuCl
3(in the hydrochloric acid with [AuCl
4]
-Form exists) etc. gold compound the concentration of gold ion is become about 100ppm.As above adjusted sample solution S is injected detection groove 5.In addition, the order that adds HCl and NaCl and gold compound in the sample solution S does not have priority.
Stir sample solution S on one side, Yi Bian use potentiostat 7 that the current potential of boron-doped diamond electrode 2 is changed to the negative potential direction, arsenic and gold and then electro-deposition are on the surface of boron-doped diamond electrode 2.This moment, when being detected object, current potential is adjusted to-0.1V with As (III); Be detected object or during for common detected object, need carry out the variation in 2 stages with As (V), at first under the current potential of-1.0V, reduce As (V), then again current potential is transferred to-0.1V current potential with As (III) and As (V).Under any situation, current potential reaches-0.1V after, remain on-0.1V by current potential within a certain period of time boron-doped diamond electrode 2, arsenic concentrated and carry out electro-deposition fully.
At being the electrochemical reaction that is taken place in the electrodeposition step of detected object, below be elaborated with As (V) or As (III) and As (V).
The standard oxidizing potential of As (V) is as follows.
2H
2AsO
4 -+6H
++4e
-＝As
2O
3+5H
2O
(E
O＝-0.036VvsAg/AgCl)
As
2O
3+H
2O＝2HAsO
2
HAsO
2+3H
++3e
-＝As+2H
2O
(E
O＝-0.036VvsAg/AgCl)
As above, on the surface of boron-doped diamond electrode 2, reduction reaction and these 2 stages of reaction of electrodeposit reaction take place in the whole process up to As (V) electro-deposition (separating out).Therefore, As (V) to carry out electro-deposition, at first need current potential to be adjusted to-1.0V, As (V) is reduced to As (III), then current potential is adjusted to-0.1V, make the surface of As (III) electro-deposition at electrode 2.
; even if carbon electrode is at the negative potential of-1.0V, also the hydrogen that can produce at electrode surface because of the water electrolysis that takes place with the electro-deposition competition takes place so the electro-deposition of As (V) is difficult; simultaneously the electrode that is made of vitreous carbon is under the negative potential about-1.0V, and electrode self also deterioration can take place.In contrast to this, boron-doped diamond electrode 2 is up under the current potential about-1.0V, and electrode surface also is difficult for producing hydrogen, more the deterioration problem can not take place.
When using in the patent documentation 3 disclosed BDD-Au electrode, added for electro-deposition As (V)-negative potential that 1.5V is so big, consequent hydrogen makes the gold that is deposited on electrode surface in advance become unstable.Also so for this reason, make and utilize BDD-Au electrode detection concentration to be the difficulty that becomes of the arsenic below the 250ppb.
In the present embodiment, at first, current potential is remained on-1.0V under, then for fear of producing hydrogen, current potential is transferred to-0.1V and keep the regular hour (10 seconds～30 seconds).In view of the above, As (V) and As (III) are with the surface of the common electro-deposition of gold at boron-doped diamond electrode 2.Can think, current potential be remained on-make As (V) revert to the state of As (III) under the 1.0V, be in order to make As (III) under its electro-deposition current potential electrodeposit reaction take place.
On the other hand, only with As (III) during as detected object, by current potential is remained on-0.1V under, As (III) and the common electro-deposition of gold are in the surface of boron-doped diamond electrode 2.
The surface of boron-doped diamond electrode 2 powers on behind deposited arsenic and the gold, stops stirrer 6, by potentiostat 7, with the current potential of boron-doped diamond electrode 2 from-0.1V is to the positive potential scanning direction, arsenic is promptly separated out in sample solution S.
Arsenic separate out generation with electric current.At this moment, with As (V) and As (III) be detected object in two stages, when adding negative potential, the total amount of As that exists among the sample solution S (V) and As (III) can be detected as the current peak of As (III).
The current value (electric signal) that this electrochemical reaction produces reaches potentiostat 7, and the signal that again each electrode is taken place carries out control detection afterwards.Potentiostat 7 detected signals send to signal conditioning package 8, and it compares the current value of gained and the relation curve between arsenic concentration that makes in advance and current value, thereby calculate the concentration of arsenic in the sample solution.
At this moment, at first, be that detected object is measured with As (V) and As (III), then, be that detected object is measured only with As (III), the concentration that deducts As (III) again from As total amount (As (III)+As (V)) concentration just can be calculated the concentration of As (V).
After electric potential scanning finishes, remain on+1.0V by the current potential with boron-doped diamond electrode 2, the gold and the residual arsenic of electro-deposition are separated out, and make boron-doped diamond electrode 2 be returned to the state before measuring and regenerate, and then electrode can use repeatedly.The regeneration of boron-doped diamond electrode 2 is not only only undertaken by current potential is maintained fixed, and can also scan repeatedly by the current potential with broad to carry out.
According to present embodiment, in sample solution S, add excessive gold, make itself and arsenic be present in the sample solution jointly, compare with use BDD-Au electrode, gold and the common electro-deposition of arsenic are in the surface of boron-doped diamond electrode 2, improved as the electrode reaction active site tremendously and had the gold of catalysis function and the contact probability of arsenic, thereby promoted the generation of the electrode reaction of arsenic significantly, made the arsenic of analyzing low concentration in high sensitivity become possibility.Therefore, according to present embodiment, use the BDD-Au electrode in the past under optimum determining condition, the detection of the arsenic below the 250ppb concentration that all is difficult to measure becomes possibility.
In addition, when using the BDD-Au electrode, must be in advance with deposition of gold on the boron-doped diamond electrode surface, and, only need that gold is joined sample solution to get final product according to present embodiment, operate extremely easy.Moreover, in the present embodiment owing to gold joined sample solution get final product, when therefore not needing picture use BDD-Au electrode, for obtain electrode in batch between performance homogenising and carry out control highly.
Further, just at last under the negative potential lower than-1.0V, the surface of carbon electrode also can take place to produce hydrogen with the water electrolysis reaction of electro-deposition competition, make the electro-deposition of As (V) become difficult, and boron-doped diamond electrode 2 under the negative potential about-1.0V, also can be reduced to As (V) As (III), owing under the negative potential about-1.0V, be difficult for producing hydrogen, so can not hinder the big As of oxidation-reduction potential (V) to carry out electro-deposition.In addition, in the present embodiment, under the negative potential about-1.0V, As (V) is reduced to As (III), during unlike use BDD-Au electrode negative potential is increased to-1.5V, just be difficult for producing hydrogen, As (V) all is improved in boron-doped diamond electrode 2 lip-deep electrodeposition efficiency to the efficient and the As (0) of the reduction reaction of As (III).
In addition, the NaCl concentration of sample solution S is transferred to 2M, the pH value is transferred to 1.0, and arsenic ion and gold ion form stable complex compound with chloride ion respectively, thus generating electrodes reaction easily, and sensitivity increases substantially.
In addition, contain excessive chloride ion among the sample solution S, the full width at half maximum of electric current crest itself is quite little, can access tangible crest.This is because the complex compound that arsenic ion and gold ion and chloride ion form has produced influence to the electronics translational speed.So also so hardly be subjected to the interference of interfering materials such as other metals.Moreover, there is excessive chloride ion among the sample solution S, can get rid of Br
-Etc. anionic influence.
Above-mentioned embodiment of the present invention is not particularly limited.
For example, detecting groove 5 unqualified be batch-type, also can use and contain the electrochemical determining device 1 that arrheas formula (the ス ト Star プ De Off ロ same form) mensuration groove 5.
Further, the electrochemical determining device 1 that above-mentioned embodiment relates to is by possessing boron-doped diamond electrode 2, three-electrode method to electrode 3 and contrast electrode 4 carries out work, but the electrochemical determining device 1 that is used to implement electrochemical determination method of the present invention also can be by only possessing boron-doped diamond electrode 2 and two electrode methods of electrode 3 being carried out work.Three-electrode method can be controlled boron-doped diamond electrode 2 and to the absolute value of impressed voltage between the electrode 3, thereby can carry out high precision and highly sensitive mensuration, and two electrode methods are only used boron-doped diamond electrode 2 and to electrode 3 these two electrodes, the feasible simple structureization that detects groove 5, miniaturization, and then make detect groove 5 can chipization, disposable use, thus carry out easier mensuration.
In sample solution S, add gold, adjust the concentration of pH value and chloride ion, again sample solution S is injected after can getting well in advance and measure groove 5, also can in measuring groove 5, carry out.In addition, electrochemical determining device 1 can be provided with before sample solution S is injected detection groove 5, carried out the interpolation of gold and the adjustment groove of adjusting pH value and chloride ion concentration.
Negative potential as making the arsenic electro-deposition on boron-doped diamond electrode 2 surfaces, be not limited to-1.0V and-0.1V, but should avoid inhaling hydrogen potential, preferably suppress the setting that hydrogen produces as far as possible, for example preferred-below the 0.5V for As (V), more preferably-1.0V about.Under electro-deposition current potential-0.1V of As (III), can not produce hydrogen.
In addition, electrochemical determining device 1 is that the device that can implement the electrochemical gaging of above-mentioned arsenic gets final product, and can be isolated plant, also can be that fexible unit combines, and the shape of device, the capacity of groove, electrode size etc. all are not particularly limited.
In addition, can the above-mentioned embodiment of appropriate combination and part or all of distortion embodiment, all distortion in not breaking away from aim of the present invention are all possible.
Embodiment
The present invention will be described in more detail below to exemplify embodiment, but the present invention is not limited to these embodiment.
Make the boron-doped diamond electrode
Use silicon plate { Si (100) } as substrate, after substrate surface is done texture processing, it is configured on microwave CVD film formation device (manufacturing of the ASTeX company) frame.It is the lysate of carbon source that film forming stoste is ready to acetone and methanol mixture (liquid of mixed volume than 9: 1), wherein is dissolved with the B as the boron source
2O
3, make its concentration with boron/carbon (B/C) than being 10
4Ppm.
Then, in this film forming stoste, feed pure H as carrier
2Behind the gas, import in the container, feed hydrogen (532ml/min) with another pipe in advance, adjust pressure to setting (115Torr=115 * 133.322Pa).Then, inject the microwave electric power of 2.45GHz, after the discharge, adjust electric power, after stablizing, in film forming stoste, feed pure H as carrier to 5kW
2Gas (15ml/min) is by microwave plasma assisted CVD method, with the speed film forming of 1～4 μ m/h.At last, reaction obtains film thickness after 8 hours and is about 30 μ m (electrode area is less than 1cm
2) the boron-doped diamond electrode.Substrate temperature is usually at 850～950 ℃.
Make the BDD-Au electrode
Use the K[Au (Cl) of the hydrochloric acid of 0.1M with 1M
4] ten times of aqueous solution dilutions, adopt chronoamperometry with the reduction 1 minute under-0.4V of this solution, by the boron-doped diamond electrode surface deposited Au of above-mentioned gained is produced the BDD-Au electrode.
Measure the concentration of As (V) solution
Use Na
2HAsO
47H
2O modulates As (V) solution of variable concentrations as As (V) source, and it is measured.
(1) boron-doped diamond electrode
At first, modulation end liquid.In the end liquid, select for use ultrapure water as solvent, it is 2M that interpolation NaCl makes its concentration, and it is 0.1M that interpolation HCl makes its concentration.Will be with respect to the standard gold solution (H[AuCl of this end liquid
4]) 1000ppm mixes with volume ratio with end liquid at 1: 9, is modulated into gold end liquid.Then, with NaAsO
2Join in the end liquid, be modulated into As (III) aqueous solution.This As (III) aqueous solution is mixed with the liquid of the golden end that is formulated to Au100ppm, as measuring.
In the mensuration system, select for use the boron-doped diamond electrode as working electrode, contrast electrode is done in the choosing of Ag/AgCl electrode, and the choosing of Pt electrode is done electrode.Then, employing can effectively detect the stripping voltammetry of micro constitutent, the originally outer negative potential that adds, and the As electro-deposition to positive potential scanning direction current potential, is measured the current value of this moment after on the electrode.
Condition determination is as follows.
(1) electro-deposition current potential-1.0V, electrodeposition time 30S (stirring 30S)
(2) electro-deposition current potential-0.1V, electrodeposition time 30S (stirring 10S, static 20S)
(3) sweep velocity 600mV/S, sweep limit-0.1～1.0V
(4) desorb current potential 1.0V keeps this current potential 30S
The result as shown in Figure 2.
(2) BDD-Au electrode
Select for use the BDD-Au electrode as working electrode, contrast electrode is done in the choosing of Ag/AgCl electrode, and the choosing of Pt electrode is done electrode, and the solution that will contain As (V) 100ppb, 300ppb, 500ppb, 800ppb, 1000ppb is respectively analyzed by following condition.Adopt stripping voltammetry, originally working electrode is added-negative potential of 1.5V, under the current potential of-0.4V, carry out electro-deposition immediately afterwards,, measure the current value of this moment then to positive potential scanning direction current potential.
Condition determination is as follows.
(1) electro-deposition current potential-1.5V
(2) electro-deposition current potential-0.4V, electrodeposition time 60S (stirring 30S, static 30S)
(3) sweep velocity 200mV/S, sweep limit-0.4～1.0V
(4) desorb current potential 1.0V keeps this current potential 30S
The result as shown in Figure 3.
(3) result
With As (V) concentration is that the situation of 100ppb is compared, and when using the BDD-Au electrode, peak point current is 0.5 μ A, and baseline tilts, and when using the boron-doped diamond electrode, peak point current is 15 μ A, and baseline values.From then on the result uses in the sample solution when having added golden boron-doped diamond and analyzing clearly as can be seen, can detect As (V) with quite high sensitivity (30 times).
The influence of pH value in the sample solution
Use the boron-doped diamond electrode as working electrode, under the said determination condition, change the pH value of the sample solution that contains As (III) 0.56ppm, originally add negative potential, the As electro-deposition again to positive potential scanning direction current potential, is measured the current value of this moment behind electrode.The result as shown in Figure 4.
As shown in Figure 4, the pH value is 1 o'clock peak point current maximum, and the shape at peak is also the most sharp-pointed.As can be known from the results, when the pH value being set at the highly acid about 1, can improve the detection sensitivity of arsenic.
Utilizability on the industry
By the present invention, can be with easy operation and device, high accuracy and detect in high sensitivity arsenic or the arsenic compound that contains in underground water etc. and measure its concentration.
Symbol description
1, electrochemical determining device
2, boron-doped diamond electrode
3, to electrode
4, reference electrode
5, detect groove
6, stirrer
7, potentiostat
8, signal conditioning package
S, sample solution
Claims (5)
1. the electrochemical determination method of an arsenic, it is a kind of use to electrode and the working electrode that is made of the conductive diamond electrode, measures the method for the arsenic concentration in the sample solution with electrochemical means, it is characterized in that, comprises following operation:
The operation that in above-mentioned sample solution, adds gold;
The electro-deposition operation, the current potential that makes above-mentioned conductive diamond electrode allows arsenic and golden electro-deposition on above-mentioned conductive diamond electrode surface to the change of negative potential direction; And
Separate out operation,, the arsenic of electro-deposition on above-mentioned conductive diamond electrode surface is parsed in said sample solution to the current potential of the above-mentioned conductive diamond electrode of positive potential scanning direction.
2. the electrochemical determination method of arsenic as claimed in claim 1, wherein the concentration of chloride ion is 1.5～2.5M in the said sample solution.
3. the electrochemical determination method of arsenic as claimed in claim 1, wherein the pH of said sample solution is acid.
4. the electrochemical determination method of arsenic as claimed in claim 1 adds gold and makes the concentration of gold become 10～1000ppm in above-mentioned sample solution.
5. electrochemical determining device, it is used for measuring the arsenic concentration that has added golden sample solution with electrochemical means, it is characterized in that, comprising:
Groove, be provided with in it to electrode and make arsenic and golden electro-deposition at this working electrode that conductive diamond electrode of electrode surface is constituted;
The potential change device, it makes the current potential of above-mentioned conductive diamond electrode change to the negative potential direction, provide and make arsenic and golden electro-deposition current potential on the surface of above-mentioned conductive diamond electrode, then, the current potential that makes above-mentioned conductive diamond electrode provides the current potential that the arsenic of electro-deposition on above-mentioned conductive diamond electrode surface is parsed to the change of positive potential direction in sample solution;
Pick-up unit, the electric current that its potential change that detects above-mentioned conductive diamond electrode causes changes;
Signal conditioning package, detected electric current variation calculates arsenic concentration according to above-mentioned detection device for it.
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| JP2009124266A JP5281481B2 (en) | 2009-05-22 | 2009-05-22 | Method and apparatus for electrochemical measurement of arsenic ion, and reagent set |
| JP2009-124266 | 2009-05-22 |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006098281A (en) * | 2004-09-30 | 2006-04-13 | Keio Gijuku | Electrode for electrochemical analysis/measurement, electrochemical analysis/measurement device, and electrochemical analysis/measurement method of inspected material concentration |
| JP2007071721A (en) * | 2005-09-07 | 2007-03-22 | Permelec Electrode Ltd | Electrode for arsenic detection, sensor using it, and arsenic concentration measuring method |
| JP2007304081A (en) * | 2006-04-10 | 2007-11-22 | Hokuto Denko Kk | Solution analysis method |
| JP2008216061A (en) * | 2007-03-05 | 2008-09-18 | Keio Gijuku | Electrochemical analysis method using boron-doped conductive diamond electrode |
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| JP2001091499A (en) * | 1999-07-19 | 2001-04-06 | Akira Fujishima | Solution analysis method |
| JP4583937B2 (en) * | 2005-01-07 | 2010-11-17 | 積水化学工業株式会社 | Method for electrochemical measurement of arsenic ions |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006098281A (en) * | 2004-09-30 | 2006-04-13 | Keio Gijuku | Electrode for electrochemical analysis/measurement, electrochemical analysis/measurement device, and electrochemical analysis/measurement method of inspected material concentration |
| JP2007071721A (en) * | 2005-09-07 | 2007-03-22 | Permelec Electrode Ltd | Electrode for arsenic detection, sensor using it, and arsenic concentration measuring method |
| JP2007304081A (en) * | 2006-04-10 | 2007-11-22 | Hokuto Denko Kk | Solution analysis method |
| JP2008216061A (en) * | 2007-03-05 | 2008-09-18 | Keio Gijuku | Electrochemical analysis method using boron-doped conductive diamond electrode |
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| DAISUKE YAMADA ET AL: "Anodic stripping voltammetry of inorganic species of As3+ and As5+ at gold-modified boron doped diamond electrodes", 《JOURNAL OF ELECTROANALYTICAL CHEMISTRY》, vol. 165, 10 January 2008 (2008-01-10), pages 145 - 153 * |
| YANG SONG ET AL: "Total inorganic arsenic detection in real water samples using anodic stripping voltammetry and a gold-coated diamond thin-film electrode", 《ANALYTICA CHIMICA ACTA》, vol. 593, 24 April 2007 (2007-04-24), pages 7 - 12 * |
| 张淑云等: "玻璃碳电极阳极溶出伏安法测定工业废水中微量砷", 《兰州大学学报》, no. 1, 31 March 1979 (1979-03-31), pages 108 - 115 * |
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| CN101893594B (en) | 2014-07-09 |
| JP2010271236A (en) | 2010-12-02 |
| JP5281481B2 (en) | 2013-09-04 |
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